diff --git a/.dockerignore b/.dockerignore
index 4611add..3b36028 100644
--- a/.dockerignore
+++ b/.dockerignore
@@ -1,5 +1,6 @@
 *
 !target/x86_64-unknown-linux-musl/release/swactor
+!target/x86_64-unknown-linux-musl/release/swactor-datastream-collector
 !target/release/swactor-diag-collector
 !target/release/swactor-diag-postproc
 !examples/single-gpu-inference/target/release/gpu-node
diff --git a/Dockerfile b/Dockerfile
index 1e65f4a..5db55b3 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,3 +1,4 @@
 FROM scratch
 COPY target/x86_64-unknown-linux-musl/release/swactor /swactor
+COPY target/x86_64-unknown-linux-musl/release/swactor-datastream-collector /collector
 ENTRYPOINT ["/swactor"]
diff --git a/crates/dashboard/Cargo.toml b/crates/dashboard/Cargo.toml
index 67a68f5..19440dd 100644
--- a/crates/dashboard/Cargo.toml
+++ b/crates/dashboard/Cargo.toml
@@ -32,6 +32,11 @@ replay-viewer = ["dep:anyhow", "dep:distribution", "distribution/collector"]
 # SSE UI folding the vast.ai fleet telemetry and the orchestrator's
 # distribution snapshot server-side.
 live-collector = ["dep:distribution", "distribution/collector"]
+# Datastream-backed dashboard: bind the demo's UDP telemetry sink, demux the
+# per-node frames, and drive the live HTTP dashboard. Only needs the
+# `distribution::datastream` module (not feature-gated there), so it stays free
+# of the heavier collector/iroh stack.
+datastream = ["dep:distribution"]
 
 [[bin]]
 name = "swactor-tui"
@@ -43,6 +48,11 @@ name = "dashboard_collector"
 path = "src/bin/dashboard_collector.rs"
 required-features = ["live-collector"]
 
+[[bin]]
+name = "swactor-datastream-dashboard"
+path = "src/bin/datastream_dashboard.rs"
+required-features = ["datastream"]
+
 [[example]]
 name = "replay_viewer"
 path = "examples/replay_viewer.rs"
diff --git a/crates/dashboard/src/bin/datastream_dashboard.rs b/crates/dashboard/src/bin/datastream_dashboard.rs
new file mode 100644
index 0000000..2188bcb
--- /dev/null
+++ b/crates/dashboard/src/bin/datastream_dashboard.rs
@@ -0,0 +1,86 @@
+//! Datastream-backed dashboard: bind the demo cluster's UDP telemetry sink
+//! (the same wire `swactor-datastream-collector` reads), demultiplex the
+//! per-node frames, and serve the live HTTP/browser dashboard from them.
+//!
+//! Drop-in for the `collector` service in the datastream demo: same UDP bind,
+//! but instead of printing frames it renders them in the existing dashboard UI.
+//!
+//! Usage: `swactor-datastream-dashboard [--bind HOST:PORT] [--port HTTP_PORT] [--node FILTER]`
+//!   --bind   UDP sink to listen on (default `0.0.0.0:7700`)
+//!   --port   HTTP dashboard port (default `9090`)
+//!   --node   show the node whose id/region/role matches FILTER (default: first seen)
+
+use dashboard::datastream_source::run_datastream_ingest;
+use dashboard::{start_dashboard, DashboardConfig};
+use tracing_subscriber::filter::LevelFilter;
+use tracing_subscriber::layer::SubscriberExt;
+use tracing_subscriber::util::SubscriberInitExt;
+
+fn main() {
+    let args = Args::parse();
+
+    let dashboard = start_dashboard(DashboardConfig {
+        port: args.port,
+        ..Default::default()
+    });
+    // Route process-output / membership tracing into the activity log panel.
+    // Cap at INFO so the panel shows our events, not tokio/mio TRACE internals.
+    tracing_subscriber::registry()
+        .with(dashboard.layer())
+        .with(LevelFilter::INFO)
+        .init();
+    dashboard.start_http_standalone();
+
+    eprintln!(
+        "datastream dashboard: serving on container port {} (UDP sink {}) — \
+         browse via the published host port:\n  \
+         /                     Overview / Actors (single node)\n  \
+         /plugin/distribution  SWIM connection graph (all nodes)\n  \
+         /plugin/vastai        Fleet table (all nodes)",
+        args.port, args.bind
+    );
+
+    // Blocks forever, demuxing frames into the dashboard's pushed stats.
+    if let Err(e) = run_datastream_ingest(&args.bind, args.node.as_deref(), &dashboard) {
+        eprintln!("datastream dashboard: fatal: failed to bind {}: {e}", args.bind);
+        std::process::exit(1);
+    }
+}
+
+struct Args {
+    bind: String,
+    port: u16,
+    node: Option<String>,
+}
+
+impl Args {
+    fn parse() -> Self {
+        let mut bind = std::env::var("SWACTOR_DATASTREAM_BIND").ok();
+        let mut port: u16 = 9090;
+        let mut node: Option<String> = None;
+
+        let mut it = std::env::args().skip(1);
+        while let Some(arg) = it.next() {
+            match arg.as_str() {
+                "--bind" => bind = it.next(),
+                "--port" => port = it.next().and_then(|v| v.parse().ok()).unwrap_or(port),
+                "--node" => node = it.next(),
+                other => {
+                    if let Some(v) = other.strip_prefix("--bind=") {
+                        bind = Some(v.to_string());
+                    } else if let Some(v) = other.strip_prefix("--port=") {
+                        port = v.parse().unwrap_or(port);
+                    } else if let Some(v) = other.strip_prefix("--node=") {
+                        node = Some(v.to_string());
+                    }
+                }
+            }
+        }
+
+        Self {
+            bind: bind.unwrap_or_else(|| "0.0.0.0:7700".to_string()),
+            port,
+            node,
+        }
+    }
+}
diff --git a/crates/dashboard/src/datastream_source.rs b/crates/dashboard/src/datastream_source.rs
new file mode 100644
index 0000000..a126653
--- /dev/null
+++ b/crates/dashboard/src/datastream_source.rs
@@ -0,0 +1,871 @@
+//! Datastream → dashboard adapter.
+//!
+//! Binds the UDP sink the demo cluster ships to (the same wire the dumb
+//! `swactor-datastream-collector` reads), **demultiplexes** the per-node frames,
+//! and drives the dashboard's *existing* views from them — no bespoke UI:
+//!
+//!   * the single-node **Overview / Actors** page (`/`) via a synthesized
+//!     [`RuntimeStats`] (each datastream channel becomes one synthetic actor row);
+//!   * the canonical **Distribution** connection-graph page
+//!     (`/plugin/distribution`, [`crate::DISTRIBUTION_PAGE_HTML`]) via a
+//!     [`DistributionNodeSnapshot`] rebuilt from the selected node's membership —
+//!     so it renders the exact SWIM graph a live node shows;
+//!   * a cross-node **Fleet** table (`/plugin/vastai`) served in the same
+//!     dashboard chrome (nav bar + palette), not a separate app.
+//!
+//! Process output and membership transitions are emitted as `tracing` events so
+//! they flow through the dashboard's activity-log path.
+//!
+//! A node is only shown while it is *live* (has shipped a frame within
+//! [`NODE_TTL`]); a node that stops streaming drops out of every view, so a
+//! restarted/departed node leaves no ghost in the graph or the fleet table.
+
+use std::collections::{HashMap, HashSet};
+use std::net::UdpSocket;
+use std::sync::{Arc, Mutex};
+use std::time::{Duration, Instant};
+
+use distribution::datastream::catalog::{
+    self, IdentityRecord, LifecycleCost, MembershipTransition, Record, ResourceSample,
+    RuntimeStats as DsRuntimeStats, TransportInternals,
+};
+use distribution::datastream::wire::decode_delivery;
+use distribution::snapshot::{DistributionNodeSnapshot, MemberInfo};
+
+use swactor::actor::ActorAddress;
+use swactor::stats::{ActorInfo, RuntimeStats, TickTiming, WorkerInfo};
+
+use crate::plugin::{DashboardPlugin, PluginResponse};
+use crate::{DashboardHandle, DISTRIBUTION_PAGE_HTML};
+
+/// A node counts as live — shown in the graph and fleet table — if it has
+/// streamed a frame within this window. Nodes ship resource/runtime/transport
+/// samples every ~1s, so a node silent past this has left the cluster; its
+/// `models` entry lingers but is filtered out of every view (no ghost nodes).
+const NODE_TTL: Duration = Duration::from_secs(8);
+
+/// Per-node accumulator: the latest value seen on each typed channel plus
+/// running membership/process state. One of these drives the display.
+#[derive(Default)]
+struct DatastreamModel {
+    identity: Option<IdentityRecord>,
+    resource: Option<ResourceSample>,
+    runtime: Option<DsRuntimeStats>,
+    transport: Option<TransportInternals>,
+    lifecycle: Option<LifecycleCost>,
+    /// peer node-id → latest liveness state.
+    membership: HashMap<String, String>,
+    /// last membership transition, formatted for display.
+    last_transition: Option<String>,
+    /// proc label → (line count, last line).
+    procs: HashMap<String, (u64, String)>,
+    first_seen: Option<Instant>,
+    last_seen: Option<Instant>,
+}
+
+/// A log line to surface through the dashboard's activity path.
+enum LogEvent {
+    Info(String),
+    Warn(String),
+}
+
+impl DatastreamModel {
+    /// Fold one frame's channel/payload into the model, returning any activity
+    /// log events it produced (process output, membership transitions).
+    fn update(&mut self, channel: &str, payload: &[u8]) -> Vec<LogEvent> {
+        let now = Instant::now();
+        self.first_seen.get_or_insert(now);
+        self.last_seen = Some(now);
+        let mut events = Vec::new();
+
+        match channel {
+            catalog::IDENTITY => {
+                if let Ok(r) = IdentityRecord::decode(payload) {
+                    self.identity = Some(r);
+                }
+            }
+            catalog::HOST_RESOURCE => {
+                if let Ok(r) = ResourceSample::decode(payload) {
+                    self.resource = Some(r);
+                }
+            }
+            catalog::RUNTIME_STATS => {
+                if let Ok(r) = DsRuntimeStats::decode(payload) {
+                    self.runtime = Some(r);
+                }
+            }
+            catalog::TRANSPORT_INTERNALS => {
+                if let Ok(r) = TransportInternals::decode(payload) {
+                    self.transport = Some(r);
+                }
+            }
+            catalog::LIFECYCLE_COST => {
+                if let Ok(r) = LifecycleCost::decode(payload) {
+                    self.lifecycle = Some(r);
+                }
+            }
+            catalog::MEMBERSHIP => {
+                if let Ok(t) = MembershipTransition::decode(payload) {
+                    // Display the short id; key the membership map by the full
+                    // id so the views can resolve it to a friendly label.
+                    let line = format!("{}: {} → {}", short_id(&t.peer), t.from, t.to);
+                    self.membership.insert(t.peer.clone(), t.to.clone());
+                    self.last_transition = Some(line.clone());
+                    events.push(LogEvent::Info(format!("membership {line}")));
+                }
+            }
+            // Raw-text process output: `proc.<label>.{stdout,stderr}`.
+            _ if channel.starts_with("proc.") => {
+                let line = String::from_utf8_lossy(payload).into_owned();
+                if let Some((label, is_err)) = parse_proc_channel(channel) {
+                    let entry = self.procs.entry(label.to_string()).or_default();
+                    entry.0 += 1;
+                    entry.1 = line.clone();
+                    let tagged = format!("[{label}] {line}");
+                    events.push(if is_err {
+                        LogEvent::Warn(tagged)
+                    } else {
+                        LogEvent::Info(tagged)
+                    });
+                }
+            }
+            // Unknown channel — ignored for display (still demuxed cleanly).
+            _ => {}
+        }
+        events
+    }
+
+    /// Has this node streamed a frame within [`NODE_TTL`]?
+    fn is_live(&self, now: Instant) -> bool {
+        self.last_seen
+            .map(|t| now.duration_since(t) < NODE_TTL)
+            .unwrap_or(false)
+    }
+
+    /// A friendly label for this node: `region · short-id` once its identity is
+    /// known, else just the short id.
+    fn label(&self, node_id: &str) -> String {
+        match &self.identity {
+            Some(idr) if !idr.region.is_empty() => {
+                format!("{} · {}", idr.region, short_id(node_id))
+            }
+            _ => short_id(node_id),
+        }
+    }
+
+    /// Total process-output lines seen across all labels.
+    fn total_proc_lines(&self) -> u64 {
+        self.procs.values().map(|(n, _)| *n).sum()
+    }
+
+    /// The peers this node currently sees that are themselves still live, as
+    /// `(peer_id, state)`. Filtering by liveness drops stale incarnations a
+    /// lost SWIM `dead` transition would otherwise leave stuck at `alive`.
+    fn live_peers<'a>(&'a self, live: &HashSet<String>) -> Vec<(&'a String, &'a String)> {
+        self.membership
+            .iter()
+            .filter(|(peer, _)| live.contains(peer.as_str()))
+            .collect()
+    }
+
+    /// Synthesize the dashboard's native stats from the accumulated datastream.
+    fn to_runtime_stats(&self) -> RuntimeStats {
+        let ds_rt = self.runtime.clone().unwrap_or(DsRuntimeStats {
+            actors_live: 0,
+            mailbox_depth: 0,
+            scheduled_tasks: 0,
+        });
+
+        // One synthetic worker = this node.
+        let worker = WorkerInfo {
+            id: 0,
+            num_actors: ds_rt.actors_live as usize,
+            mailbox_depth: ds_rt.mailbox_depth as usize,
+            messages_processed: self.total_proc_lines(),
+            local_sends: 0,
+            cross_sends: 0,
+            inbox_sends: 0,
+            type_mismatches: 0,
+            panics: 0,
+            messages_dropped: 0,
+            restarts: 0,
+            stops: 0,
+        };
+
+        // Each datastream channel becomes one synthetic actor row, with columns
+        // and the per-actor breakdown chart repurposed to show its values.
+        let mut actor_details: Vec<ActorInfo> = Vec::new();
+
+        if let Some(r) = &self.resource {
+            actor_details.push(synth_actor(
+                "host.resource",
+                Some(format!(
+                    "cpu {:.0}% mem {}/{}MB",
+                    r.cpu_pct, r.mem_used_mb, r.mem_total_mb
+                )),
+                self.total_proc_lines(),
+                vec![
+                    ("cpu_pct".to_string(), r.cpu_pct.round() as u64),
+                    ("mem_used_mb".to_string(), r.mem_used_mb as u64),
+                    ("mem_total_mb".to_string(), r.mem_total_mb as u64),
+                    ("gpu_pct".to_string(), r.gpu_pct.round() as u64),
+                    ("disk_used_gb".to_string(), r.disk_used_gb as u64),
+                    ("net_rx_kbps".to_string(), r.net_rx_kbps as u64),
+                    ("net_tx_kbps".to_string(), r.net_tx_kbps as u64),
+                ],
+            ));
+        }
+
+        if let Some(t) = &self.transport {
+            actor_details.push(synth_actor(
+                "transport.internals",
+                Some(format!(
+                    "relay {} · {} direct · {} relayed",
+                    if t.relay_connected { "up" } else { "down" },
+                    t.direct_peers,
+                    t.relay_peers
+                )),
+                0,
+                vec![
+                    ("relay_connected".to_string(), t.relay_connected as u64),
+                    ("direct_peers".to_string(), t.direct_peers as u64),
+                    ("relay_peers".to_string(), t.relay_peers as u64),
+                    ("rtt_ms_p50".to_string(), t.rtt_ms_p50 as u64),
+                ],
+            ));
+        }
+
+        if !self.membership.is_empty() || self.last_transition.is_some() {
+            let mut counts: HashMap<&str, u64> = HashMap::new();
+            for state in self.membership.values() {
+                *counts.entry(state.as_str()).or_default() += 1;
+            }
+            let breakdown = counts
+                .into_iter()
+                .map(|(k, v)| (k.to_string(), v))
+                .collect();
+            actor_details.push(synth_actor(
+                "membership",
+                self.last_transition.clone(),
+                self.membership.len() as u64,
+                breakdown,
+            ));
+        }
+
+        // One row per process label, newest line as "last message".
+        let mut procs: Vec<(&String, &(u64, String))> = self.procs.iter().collect();
+        procs.sort_by(|a, b| a.0.cmp(b.0));
+        for (label, (count, last)) in procs {
+            actor_details.push(synth_actor(
+                &format!("proc.{label}"),
+                Some(last.clone()),
+                *count,
+                vec![("lines".to_string(), *count)],
+            ));
+        }
+
+        let actors = actor_details
+            .iter()
+            .map(|a| (a.address, a.worker_id))
+            .collect();
+
+        let uptime_ms = self
+            .lifecycle
+            .as_ref()
+            .map(|l| l.uptime_s * 1000)
+            .unwrap_or_else(|| {
+                self.first_seen
+                    .map(|t| t.elapsed().as_millis() as u64)
+                    .unwrap_or(0)
+            });
+
+        RuntimeStats {
+            num_workers: 1,
+            uptime_ms,
+            actors,
+            workers: vec![worker],
+            actor_details,
+            // No per-tick phase timing on the wire; one empty worker entry keeps
+            // the phase bars degrading to a single fill rather than panicking.
+            tick_timings: vec![Vec::<TickTiming>::new()],
+        }
+    }
+
+    /// Does this node match the optional selection filter? Matches against the
+    /// node id and (once known) the identity region/role.
+    fn matches(&self, node_id: &str, filter: &str) -> bool {
+        if node_id.contains(filter) {
+            return true;
+        }
+        match &self.identity {
+            Some(id) => {
+                id.region == filter || format!("{:?}", id.role).eq_ignore_ascii_case(filter)
+            }
+            None => false,
+        }
+    }
+
+    /// Rebuild a [`DistributionNodeSnapshot`] for this node from the demuxed
+    /// stream, so the canonical Distribution page renders its SWIM connection
+    /// graph exactly as it would for a live node. Only live peers are included
+    /// (`peer_labels`/`live` are the fleet-wide label map and live set).
+    ///
+    /// Fields the datastream does not carry (routing table, cache, directory,
+    /// registry) are honest zeros — the graph and membership panel, which is all
+    /// this view exists to show, are driven entirely by `members`.
+    fn dist_snapshot(
+        &self,
+        node_id: &str,
+        peer_labels: &HashMap<String, String>,
+        live: &HashSet<String>,
+    ) -> DistributionNodeSnapshot {
+        let mut members: Vec<MemberInfo> = self
+            .live_peers(live)
+            .into_iter()
+            .map(|(peer, state)| MemberInfo {
+                node_id: peer.clone(),
+                addr: None,
+                state: state.clone(),
+                incarnation: 0,
+                is_authorized: None,
+                label: None,
+                relay_url: None,
+                node_name: Some(peer_labels.get(peer).cloned().unwrap_or_else(|| short_id(peer))),
+            })
+            .collect();
+        members.sort_by(|a, b| a.node_id.cmp(&b.node_id));
+
+        let count = |want: &str| members.iter().filter(|m| m.state == want).count();
+        let (alive_count, suspect_count, dead_count) =
+            (count("alive"), count("suspect"), count("dead"));
+
+        DistributionNodeSnapshot {
+            node_id: node_id.to_string(),
+            listen_addr: None,
+            members,
+            alive_count,
+            suspect_count,
+            dead_count,
+            routing_table_size: 0,
+            routing_buckets: Vec::new(),
+            routing_neighbors: Vec::new(),
+            cache_size: 0,
+            cache_entries: Vec::new(),
+            directory_entry_count: 0,
+            repair_queue_size: 0,
+            registry_size: 0,
+            registry_tombstones: 0,
+            registry_entries: Vec::new(),
+            recent_probe_targets: Vec::new(),
+            peer_auth_mode: "open".into(),
+            authorized_peer_count: None,
+            node_name: Some(peer_labels.get(node_id).cloned().unwrap_or_else(|| short_id(node_id))),
+            invite_code: None,
+            // `relay_url` means "this node runs an embedded relay server" (it
+            // draws a teal ring in the graph) — not "is connected to a relay".
+            // The datastream doesn't carry that, so leave it unset.
+            relay_url: None,
+            version: None,
+            join_statuses: Vec::new(),
+        }
+    }
+
+    /// A compact per-node summary row for the fleet table.
+    fn node_summary(
+        &self,
+        node_id: &str,
+        expected_peers: usize,
+        selected: bool,
+        live: &HashSet<String>,
+    ) -> serde_json::Value {
+        let peers = self.live_peers(live);
+        let count = |want: &str| peers.iter().filter(|(_, s)| s.as_str() == want).count() as u32;
+        let (alive, suspect, dead) = (count("alive"), count("suspect"), count("dead"));
+        let seen = peers.len();
+        // "Converged" from this node's vantage: it sees every other live node,
+        // all alive (no suspect/dead).
+        let converged = suspect == 0 && dead == 0 && seen >= expected_peers && expected_peers > 0;
+
+        let r = self.resource.as_ref();
+        let t = self.transport.as_ref();
+        let rt = self.runtime.as_ref();
+        let id = self.identity.as_ref();
+        let last_proc = self
+            .procs
+            .values()
+            .map(|(_, line)| line.clone())
+            .last()
+            .unwrap_or_default();
+
+        serde_json::json!({
+            "id": node_id,
+            "short": short_id(node_id),
+            "region": id.map(|i| i.region.clone()).unwrap_or_default(),
+            "role": id.map(|i| format!("{:?}", i.role).to_lowercase()).unwrap_or_default(),
+            "selected": selected,
+            "cpu_pct": r.map(|r| r.cpu_pct.round() as u32).unwrap_or(0),
+            "mem_used_mb": r.map(|r| r.mem_used_mb).unwrap_or(0),
+            "mem_total_mb": r.map(|r| r.mem_total_mb).unwrap_or(0),
+            "gpu_pct": r.map(|r| r.gpu_pct.round() as u32).unwrap_or(0),
+            "actors_live": rt.map(|r| r.actors_live).unwrap_or(0),
+            "mailbox_depth": rt.map(|r| r.mailbox_depth).unwrap_or(0),
+            "relay_connected": t.map(|t| t.relay_connected).unwrap_or(false),
+            "direct_peers": t.map(|t| t.direct_peers).unwrap_or(0),
+            "relay_peers": t.map(|t| t.relay_peers).unwrap_or(0),
+            "rtt_ms_p50": t.map(|t| t.rtt_ms_p50).unwrap_or(0),
+            "alive": alive,
+            "suspect": suspect,
+            "dead": dead,
+            "converged": converged,
+            "proc_lines": self.total_proc_lines(),
+            "last_proc": last_proc,
+        })
+    }
+}
+
+/// `node-id → "region · short-id"` for every demuxed node.
+fn build_labels(models: &HashMap<String, DatastreamModel>) -> HashMap<String, String> {
+    models.iter().map(|(id, m)| (id.clone(), m.label(id))).collect()
+}
+
+/// The set of node ids currently live (streamed within [`NODE_TTL`]).
+fn live_set(models: &HashMap<String, DatastreamModel>, now: Instant) -> HashSet<String> {
+    models
+        .iter()
+        .filter(|(_, m)| m.is_live(now))
+        .map(|(id, _)| id.clone())
+        .collect()
+}
+
+/// Build the Fleet-table JSON model from every *live* demuxed node.
+fn fleet_json(
+    models: &HashMap<String, DatastreamModel>,
+    selected: Option<&str>,
+    live: &HashSet<String>,
+) -> String {
+    let node_count = live.len();
+    let expected_peers = node_count.saturating_sub(1);
+    let mut nodes: Vec<serde_json::Value> = models
+        .iter()
+        .filter(|(id, _)| live.contains(id.as_str()))
+        .map(|(id, m)| m.node_summary(id, expected_peers, selected == Some(id.as_str()), live))
+        .collect();
+    // Stable order: region then short id, so rows don't jump around.
+    nodes.sort_by(|a, b| {
+        (a["region"].as_str(), a["short"].as_str())
+            .cmp(&(b["region"].as_str(), b["short"].as_str()))
+    });
+    // Whole fleet converged once every node has converged and there's >1 node.
+    let converged =
+        node_count > 1 && nodes.iter().all(|n| n["converged"].as_bool() == Some(true));
+
+    serde_json::json!({
+        "node_count": node_count,
+        "converged": converged,
+        "nodes": nodes,
+    })
+    .to_string()
+}
+
+/// Plugin backed by a shared cache string: serves a fixed HTML page, emits its
+/// cache on the SSE stream under `name`, and answers `GET /api/plugin/{name}`.
+/// Used for both the Fleet table (`vastai`) and the Distribution graph
+/// (`distribution`); each is fed by [`run_datastream_ingest`].
+struct CachePlugin {
+    name: &'static str,
+    page: &'static str,
+    cache: Arc<Mutex<Option<String>>>,
+}
+
+impl CachePlugin {
+    fn new(name: &'static str, page: &'static str, cache: Arc<Mutex<Option<String>>>) -> Self {
+        Self { name, page, cache }
+    }
+}
+
+impl DashboardPlugin for CachePlugin {
+    fn name(&self) -> &str {
+        self.name
+    }
+
+    fn snapshot_json(&self) -> Option<String> {
+        self.cache.lock().unwrap().clone()
+    }
+
+    fn handle_request(
+        &self,
+        method: &str,
+        path: &str,
+        _query: &HashMap<String, String>,
+        _body: &[u8],
+    ) -> PluginResponse {
+        match (method, path) {
+            ("GET", "" | "model" | "snapshot") => {
+                PluginResponse::json(self.cache.lock().unwrap().clone().unwrap_or_else(|| "{}".into()))
+            }
+            // The Distribution page has Re-peer / dismiss buttons; in this
+            // read-only datastream view they are inert (acknowledged, no-op).
+            ("POST", "rejoin" | "clear_status") => PluginResponse::json(r#"{"ok":true}"#.into()),
+            _ => PluginResponse::not_found(),
+        }
+    }
+
+    fn html_page(&self) -> Option<&str> {
+        Some(self.page)
+    }
+}
+
+/// Minimal `peers` plugin so the Distribution page's `fetch('/api/plugin/peers')`
+/// resolves cleanly (open auth, no managed peer list) instead of 404ing. Silent
+/// on the SSE stream.
+struct PeersStub;
+
+impl DashboardPlugin for PeersStub {
+    fn name(&self) -> &str {
+        "peers"
+    }
+    fn snapshot_json(&self) -> Option<String> {
+        None
+    }
+    fn handle_request(
+        &self,
+        method: &str,
+        path: &str,
+        _query: &HashMap<String, String>,
+        _body: &[u8],
+    ) -> PluginResponse {
+        match (method, path) {
+            ("GET", "" | "list") => PluginResponse::json(r#"{"mode":"open","peers":[]}"#.into()),
+            _ => PluginResponse::not_found(),
+        }
+    }
+}
+
+/// Build one synthetic actor row with a deterministic address from its name.
+///
+/// `mailbox_depth` is always 0: a datastream channel is not a real mailbox, and
+/// the dashboard's WarningDetector flags any row with `depth > 0` whose
+/// `messages_processed` is flat as a "stalled actor". The channel's real values
+/// live in `last_msg_type` and the `message_type_counts` breakdown instead.
+fn synth_actor(
+    name: &str,
+    last_msg_type: Option<String>,
+    messages_processed: u64,
+    message_type_counts: Vec<(String, u64)>,
+) -> ActorInfo {
+    ActorInfo {
+        address: addr_from(name),
+        worker_id: 0,
+        mailbox_depth: 0,
+        last_msg_type,
+        messages_processed,
+        poisoned: false,
+        name: Some(name.to_string()),
+        message_type_counts,
+    }
+}
+
+/// Deterministic 32-byte address from a channel name (FNV-1a in the first 8
+/// bytes — which is what the address Hash/Display use — plus the name splatted
+/// after for readability). Stable across frames so sparklines accumulate.
+fn addr_from(name: &str) -> ActorAddress {
+    let mut bytes = [0u8; 32];
+    let mut hash: u64 = 0xcbf2_9ce4_8422_2325;
+    for b in name.bytes() {
+        hash ^= b as u64;
+        hash = hash.wrapping_mul(0x0100_0000_01b3);
+    }
+    bytes[..8].copy_from_slice(&hash.to_le_bytes());
+    for (i, b) in name.bytes().take(24).enumerate() {
+        bytes[8 + i] = b;
+    }
+    ActorAddress(bytes)
+}
+
+/// Split `proc.<label>.stdout` / `proc.<label>.stderr` into `(label, is_stderr)`.
+fn parse_proc_channel(channel: &str) -> Option<(&str, bool)> {
+    let rest = channel.strip_prefix("proc.")?;
+    if let Some(label) = rest.strip_suffix(".stderr") {
+        Some((label, true))
+    } else {
+        rest.strip_suffix(".stdout").map(|label| (label, false))
+    }
+}
+
+/// First 8 chars of an id — the readable short form used throughout the views.
+fn short_id(id: &str) -> String {
+    id[..id.len().min(8)].to_string()
+}
+
+/// Bind the UDP datastream sink, demux frames, and drive the dashboard's views.
+/// Blocks forever, like the dumb collector's `main`.
+///
+/// Registers three plugins fed off the demuxed stream:
+///   * `distribution` — the canonical SWIM connection-graph page, snapshotting
+///     the selected node;
+///   * `vastai` (the nav's "Fleet") — the cross-node telemetry table;
+///   * `peers` — an open-auth stub so the graph page's peer fetch resolves.
+///
+/// The single-node Overview/Actors page is driven via `handle.set_stats`.
+pub fn run_datastream_ingest(
+    bind: &str,
+    node_filter: Option<&str>,
+    handle: &DashboardHandle,
+) -> std::io::Result<()> {
+    let sock = UdpSocket::bind(bind)?;
+    eprintln!("datastream dashboard: listening on {bind} (one frame per datagram)");
+
+    // Distribution graph (selected node) and Fleet table (all live nodes), each
+    // a shared cache the ingest loop refreshes and the SSE loop fans out.
+    let dist_cache: Arc<Mutex<Option<String>>> = Arc::new(Mutex::new(None));
+    let fleet_cache: Arc<Mutex<Option<String>>> = Arc::new(Mutex::new(None));
+    handle.register_plugin(Arc::new(CachePlugin::new(
+        "distribution",
+        DISTRIBUTION_PAGE_HTML,
+        Arc::clone(&dist_cache),
+    )) as Arc<dyn DashboardPlugin>);
+    handle.register_plugin(Arc::new(CachePlugin::new(
+        "vastai",
+        FLEET_HTML,
+        Arc::clone(&fleet_cache),
+    )) as Arc<dyn DashboardPlugin>);
+    // The base dashboard nav has a Datastore link; the datastream carries no
+    // datastore, so serve an honest "not available" page in-chrome rather than
+    // 404ing. Empty cache → silent on the SSE stream.
+    handle.register_plugin(Arc::new(CachePlugin::new(
+        "datastore",
+        DATASTORE_HTML,
+        Arc::new(Mutex::new(None)),
+    )) as Arc<dyn DashboardPlugin>);
+    handle.register_plugin(Arc::new(PeersStub) as Arc<dyn DashboardPlugin>);
+
+    let mut models: HashMap<String, DatastreamModel> = HashMap::new();
+    let mut selected: Option<String> = None;
+    // 64 KiB comfortably exceeds a UDP datagram; a frame never spans datagrams.
+    let mut buf = vec![0u8; 64 * 1024];
+
+    loop {
+        let (n, _src) = match sock.recv_from(&mut buf) {
+            Ok(v) => v,
+            Err(e) => {
+                eprintln!("datastream dashboard: recv error: {e}");
+                continue;
+            }
+        };
+        let (stream, frame) = match decode_delivery(&buf[..n]) {
+            Ok(v) => v,
+            Err(e) => {
+                eprintln!("datastream dashboard: dropped malformed datagram ({n} B): {e:?}");
+                continue;
+            }
+        };
+
+        let node = stream.node.as_str().to_string();
+        let model = models.entry(node.clone()).or_default();
+        let events = model.update(frame.channel.as_str(), &frame.payload);
+
+        // Pick the display node: first matching the filter, else first seen.
+        if selected.is_none() {
+            let qualifies = match node_filter {
+                Some(f) => model.matches(&node, f),
+                None => true,
+            };
+            if qualifies {
+                eprintln!("datastream dashboard: displaying node {}", short_id(&node));
+                selected = Some(node.clone());
+            }
+        }
+
+        if selected.as_deref() == Some(node.as_str()) {
+            // Surface process output / membership through the activity log.
+            for ev in events {
+                match ev {
+                    LogEvent::Info(m) => tracing::info!(target: "datastream", "{m}"),
+                    LogEvent::Warn(m) => tracing::warn!(target: "datastream", "{m}"),
+                }
+            }
+            handle.set_stats(model.to_runtime_stats());
+        }
+
+        // Refresh both views from the current live nodes on each frame.
+        let now = Instant::now();
+        let live = live_set(&models, now);
+        let labels = build_labels(&models);
+        *fleet_cache.lock().unwrap() = Some(fleet_json(&models, selected.as_deref(), &live));
+        if let Some(sel) = selected.as_deref() {
+            if let Some(m) = models.get(sel) {
+                let snap = m.dist_snapshot(sel, &labels, &live);
+                if let Ok(json) = serde_json::to_string(&snap) {
+                    *dist_cache.lock().unwrap() = Some(json);
+                }
+            }
+        }
+    }
+}
+
+/// Cross-node **Fleet** table, served in the dashboard's own chrome (the same
+/// header / nav bar / palette as the Overview and Distribution pages, so it is a
+/// section of the one app — not a separate UI). Renders the `vastai` SSE event
+/// built by [`fleet_json`]: one row per live node with its resource / runtime /
+/// transport telemetry and a fleet-wide SWIM-convergence pill.
+const FLEET_HTML: &str = r#"<!doctype html>
+<html lang="en">
+<head>
+<meta charset="UTF-8">
+<meta name="viewport" content="width=device-width, initial-scale=1.0">
+<title>Swactor Runtime – Fleet</title>
+<style>
+  * { margin: 0; padding: 0; box-sizing: border-box; }
+  body { font-family: 'Menlo', 'Consolas', 'Monaco', monospace; background: #0f1117; color: #e0e0e0; font-size: 13px; }
+  .header { display: flex; align-items: center; justify-content: space-between;
+    padding: 12px 20px; background: #161822; border-bottom: 1px solid #2a2d3e; }
+  .header-left { display: flex; align-items: center; }
+  .header h1 { font-size: 16px; font-weight: 600; color: #fff; }
+  .status-dot { width: 10px; height: 10px; border-radius: 50%; background: #4caf50;
+    display: inline-block; margin-left: 8px; vertical-align: middle; }
+  .status-dot.disconnected { background: #f44336; }
+  .status-dot.done { background: #ff9800; }
+  .nav-links { display: flex; gap: 4px; margin-left: 20px; }
+  .nav-link { color: #888; text-decoration: none; font-size: 12px;
+    padding: 4px 10px; border-radius: 3px; transition: color 0.2s; }
+  .nav-link:hover { color: #e0e0e0; }
+  .nav-link.active { color: #fff; background: #2a2d3e; }
+  .header-right { display: flex; align-items: center; gap: 12px; }
+  .pill { padding: 3px 12px; border-radius: 999px; font-size: 12px; font-weight: 600; }
+  .pill.ok { background: #14361f; color: #4ade80; }
+  .pill.warn { background: #3a2d12; color: #fbbf24; }
+  .content { padding: 16px 20px; }
+  table { width: 100%; border-collapse: collapse; }
+  th, td { text-align: left; padding: 7px 12px; border-bottom: 1px solid #1f2230; white-space: nowrap; }
+  th { color: #888; font-weight: 600; font-size: 11px; text-transform: uppercase; letter-spacing: .5px; }
+  td.num { text-align: right; font-variant-numeric: tabular-nums; }
+  tr.sel td { background: #161e2e; }
+  .tag { padding: 1px 8px; border-radius: 4px; background: #1c1f2e; color: #888; font-size: 11px; }
+  .tag.coordinator { background: #1c2d4a; color: #79c0ff; }
+  .tag.worker { background: #1a2e2e; color: #56d4dd; }
+  .bar { display: inline-block; width: 64px; height: 7px; background: #1c1f2e; border-radius: 4px;
+    overflow: hidden; vertical-align: middle; margin-right: 6px; }
+  .bar > i { display: block; height: 100%; background: #4ade80; }
+  .bar > i.hi { background: #fbbf24; } .bar > i.crit { background: #f87171; }
+  .st { padding: 1px 6px; border-radius: 4px; font-weight: 600; font-size: 11px; }
+  .st.suspect { background: #3a2d12; color: #fbbf24; } .st.dead { background: #3a1518; color: #f87171; }
+  .muted { color: #666; }
+  .last { max-width: 380px; overflow: hidden; text-overflow: ellipsis; color: #999; }
+</style>
+</head>
+<body>
+<div class="header">
+  <div class="header-left">
+    <h1>Swactor Runtime Dashboard <span id="statusDot" class="status-dot disconnected"></span></h1>
+    <nav class="nav-links">
+      <a href="/" class="nav-link">Overview</a>
+      <a href="/actors" class="nav-link">Actors</a>
+      <a href="/plugin/distribution" class="nav-link">Distribution</a>
+      <a href="/plugin/datastore" class="nav-link">Datastore</a>
+      <a href="/plugin/vastai" class="nav-link active">Fleet</a>
+    </nav>
+  </div>
+  <div class="header-right">
+    <span id="conv" class="pill warn">SWIM: …</span>
+  </div>
+</div>
+<div class="content">
+  <table>
+    <thead><tr>
+      <th>node</th><th>region</th><th>role</th><th>CPU</th><th>mem</th>
+      <th class="num">actors</th><th class="num">mbox</th><th>transport</th>
+      <th class="num">peers</th><th class="num">proc</th><th>last line</th>
+    </tr></thead>
+    <tbody id="rows"></tbody>
+  </table>
+  <p id="empty" class="muted" style="margin-top:12px;">waiting for telemetry…</p>
+</div>
+<script>
+(function () {
+  var state = { node_count: 0, converged: false, nodes: [] };
+  function esc(s){ return String(s==null?"":s).replace(/[&<>]/g, function(c){
+    return {"&":"&amp;","<":"&lt;",">":"&gt;"}[c]; }); }
+  function bar(pct){ var c = pct>=90?"crit":pct>=70?"hi":"";
+    return '<span class="bar"><i class="'+c+'" style="width:'+Math.min(100,pct)+'%"></i></span>'+pct+'%'; }
+
+  function render(){
+    var conv = document.getElementById("conv");
+    if (state.node_count > 1 && state.converged){ conv.className="pill ok"; conv.textContent="SWIM: converged ("+state.node_count+" nodes)"; }
+    else { conv.className="pill warn"; conv.textContent="SWIM: converging ("+state.node_count+" nodes)"; }
+
+    var rows = state.nodes.map(function(n){
+      var peers = n.alive + (n.suspect?(' <span class="st suspect">'+n.suspect+'</span>'):'')
+                + (n.dead?(' <span class="st dead">'+n.dead+'</span>'):'');
+      return '<tr class="'+(n.selected?"sel":"")+'">'
+        + '<td>'+esc(n.short)+(n.selected?' <span class="muted">(shown)</span>':'')+'</td>'
+        + '<td>'+esc(n.region)+'</td>'
+        + '<td><span class="tag '+esc(n.role)+'">'+esc(n.role||"?")+'</span></td>'
+        + '<td>'+bar(n.cpu_pct)+'</td>'
+        + '<td>'+n.mem_used_mb+'/'+n.mem_total_mb+'MB</td>'
+        + '<td class="num">'+n.actors_live+'</td>'
+        + '<td class="num">'+n.mailbox_depth+'</td>'
+        + '<td>'+(n.relay_connected?'relay ':'')+n.direct_peers+'d/'+n.relay_peers+'r</td>'
+        + '<td class="num">'+peers+'</td>'
+        + '<td class="num">'+n.proc_lines+'</td>'
+        + '<td class="last">'+esc(n.last_proc)+'</td>'
+        + '</tr>';
+    }).join("");
+    document.getElementById("rows").innerHTML = rows;
+    document.getElementById("empty").style.display = state.nodes.length ? "none" : "block";
+  }
+
+  function onModel(m){ if(!m||!m.nodes) return; state = m; render(); }
+
+  fetch("/api/plugin/vastai/model").then(function(r){return r.json();}).then(onModel).catch(function(){});
+  var dot = document.getElementById("statusDot");
+  var es = new EventSource("/events");
+  es.onopen = function(){ dot.className = "status-dot"; };
+  es.onerror = function(){ dot.className = "status-dot disconnected"; };
+  es.addEventListener("vastai", function(e){ try { onModel(JSON.parse(e.data)); } catch(err){} });
+  es.addEventListener("done", function(){ dot.className = "status-dot done"; es.close(); });
+  window.addEventListener("beforeunload", function(){ es.close(); });
+})();
+</script>
+</body>
+</html>"#;
+
+/// Honest in-chrome placeholder for the Datastore nav link: the datastream demo
+/// ships no datastore telemetry, so rather than 404 the link, explain that.
+const DATASTORE_HTML: &str = r#"<!doctype html>
+<html lang="en">
+<head>
+<meta charset="UTF-8">
+<meta name="viewport" content="width=device-width, initial-scale=1.0">
+<title>Swactor Runtime – Datastore</title>
+<style>
+  * { margin: 0; padding: 0; box-sizing: border-box; }
+  body { font-family: 'Menlo', 'Consolas', 'Monaco', monospace; background: #0f1117; color: #e0e0e0; font-size: 13px; }
+  .header { display: flex; align-items: center; padding: 12px 20px; background: #161822; border-bottom: 1px solid #2a2d3e; }
+  .header h1 { font-size: 16px; font-weight: 600; color: #fff; }
+  .nav-links { display: flex; gap: 4px; margin-left: 20px; }
+  .nav-link { color: #888; text-decoration: none; font-size: 12px; padding: 4px 10px; border-radius: 3px; }
+  .nav-link:hover { color: #e0e0e0; }
+  .nav-link.active { color: #fff; background: #2a2d3e; }
+  .note { margin: 80px auto; max-width: 520px; text-align: center; color: #888; line-height: 1.6; }
+  .note b { color: #cbd5e1; }
+</style>
+</head>
+<body>
+<div class="header">
+  <h1>Swactor Runtime Dashboard</h1>
+  <nav class="nav-links">
+    <a href="/" class="nav-link">Overview</a>
+    <a href="/actors" class="nav-link">Actors</a>
+    <a href="/plugin/distribution" class="nav-link">Distribution</a>
+    <a href="/plugin/datastore" class="nav-link active">Datastore</a>
+    <a href="/plugin/vastai" class="nav-link">Fleet</a>
+  </nav>
+</div>
+<div class="note">
+  <p><b>No datastore in this view.</b></p>
+  <p>This dashboard is fed by the per-node telemetry <b>datastream</b>, which does not
+     carry datastore contents. See <a href="/plugin/distribution" class="nav-link">Distribution</a>
+     for the cluster connection graph or <a href="/plugin/vastai" class="nav-link">Fleet</a> for per-node telemetry.</p>
+</div>
+</body>
+</html>"#;
diff --git a/crates/node/src/plugins/distribution_page.html b/crates/dashboard/src/distribution_page.html
similarity index 99%
rename from crates/node/src/plugins/distribution_page.html
rename to crates/dashboard/src/distribution_page.html
index 843c843..320df3d 100644
--- a/crates/node/src/plugins/distribution_page.html
+++ b/crates/dashboard/src/distribution_page.html
@@ -873,7 +873,9 @@
   function setToken(t) { dashToken = t; }
 
   function fetchPeers() {
-    fetch('/api/plugin/peers')
+    // The plugin API route requires a non-empty sub-path ('' 404s), and the
+    // peers plugin answers GET .../list — so query that, not the bare name.
+    fetch('/api/plugin/peers/list')
       .then(function(r) { return r.json(); })
       .then(function(d) { renderPeers(d); })
       .catch(function() {});
diff --git a/crates/dashboard/src/lib.rs b/crates/dashboard/src/lib.rs
index 1bd6c67..1536346 100644
--- a/crates/dashboard/src/lib.rs
+++ b/crates/dashboard/src/lib.rs
@@ -15,6 +15,15 @@ pub mod tui;
 #[cfg(feature = "live-collector")]
 pub mod live_collector;
 
+#[cfg(feature = "datastream")]
+pub mod datastream_source;
+
+/// The canonical Distribution page (the SWIM connection-graph view). Owned by
+/// the dashboard crate so every front-end that serves it — a live node's
+/// `DistributionPlugin` and the datastream dashboard — renders the exact same
+/// page and chrome, fed by a [`distribution::snapshot::DistributionNodeSnapshot`].
+pub const DISTRIBUTION_PAGE_HTML: &str = include_str!("distribution_page.html");
+
 use std::io;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Arc, Mutex};
@@ -106,6 +115,9 @@ pub struct DashboardHandle {
     store: Arc<EventStore>,
     runtime: Arc<Mutex<Option<Arc<Runtime>>>>,
     collector: Arc<Mutex<Option<Arc<StatsCollector>>>>,
+    /// Externally pushed stats, used when no live `Runtime` is attached (e.g. a
+    /// datastream-backed source synthesizes `RuntimeStats` and pushes them here).
+    pushed_stats: Arc<Mutex<Option<RuntimeStats>>>,
     shutdown: Arc<AtomicBool>,
     shutdown_notify: Arc<tokio::sync::Notify>,
     stats_timeline: Arc<ArrayQueue<TimestampedStats>>,
@@ -141,6 +153,13 @@ impl DashboardHandle {
         *self.collector.lock().unwrap() = Some(collector);
     }
 
+    /// Push a stats snapshot from an external source (latest wins). When no live
+    /// `Runtime` is attached, the SSE loop serves these to the dashboard exactly
+    /// as if they came from a runtime. Used by the datastream source.
+    pub fn set_stats(&self, stats: RuntimeStats) {
+        *self.pushed_stats.lock().unwrap() = Some(stats);
+    }
+
     /// Whether trace recording is enabled.
     pub fn is_recording(&self) -> bool {
         self.recording
@@ -205,6 +224,7 @@ impl DashboardHandle {
             store: Arc::clone(&self.store),
             runtime: Arc::clone(&self.runtime),
             collector: Arc::clone(&self.collector),
+            pushed_stats: Arc::clone(&self.pushed_stats),
             shutdown: Arc::clone(&self.shutdown),
             shutdown_notify: Arc::clone(&self.shutdown_notify),
             history: Arc::clone(&self.history),
@@ -252,6 +272,7 @@ pub fn start_dashboard(config: DashboardConfig) -> DashboardHandle {
     ));
     let runtime: Arc<Mutex<Option<Arc<Runtime>>>> = Arc::new(Mutex::new(None));
     let collector: Arc<Mutex<Option<Arc<StatsCollector>>>> = Arc::new(Mutex::new(None));
+    let pushed_stats: Arc<Mutex<Option<RuntimeStats>>> = Arc::new(Mutex::new(None));
     let shutdown = Arc::new(AtomicBool::new(false));
     let shutdown_notify = Arc::new(tokio::sync::Notify::new());
     let stats_timeline = Arc::new(ArrayQueue::new(config.record_stats_capacity.max(1)));
@@ -292,6 +313,7 @@ pub fn start_dashboard(config: DashboardConfig) -> DashboardHandle {
         store,
         runtime,
         collector,
+        pushed_stats,
         shutdown,
         shutdown_notify,
         stats_timeline,
diff --git a/crates/dashboard/src/server.rs b/crates/dashboard/src/server.rs
index 1e187ae..131a70e 100644
--- a/crates/dashboard/src/server.rs
+++ b/crates/dashboard/src/server.rs
@@ -40,6 +40,8 @@ pub(crate) struct AppState {
     pub store: Arc<EventStore>,
     pub runtime: Arc<Mutex<Option<Arc<Runtime>>>>,
     pub collector: Arc<Mutex<Option<Arc<StatsCollector>>>>,
+    /// Externally pushed stats, served when no live `Runtime` is attached.
+    pub pushed_stats: Arc<Mutex<Option<swactor::stats::RuntimeStats>>>,
     pub shutdown: Arc<AtomicBool>,
     pub shutdown_notify: Arc<tokio::sync::Notify>,
     pub history: Arc<DashboardHistory>,
@@ -163,6 +165,7 @@ async fn handle_live_sse(
             // Send stats if runtime is available
             {
                 let maybe_rt = state.runtime.lock().unwrap().clone();
+                let maybe_pushed = state.pushed_stats.lock().unwrap().clone();
                 if let Some(rt) = maybe_rt {
                     let mut stats = rt.stats();
                     if let Some(col) = state.collector.lock().unwrap().as_ref() {
@@ -185,6 +188,32 @@ async fn handle_live_sse(
                     }
 
                     // Send topology every 5th tick (~1/sec)
+                    tick_count += 1;
+                    if tick_count.is_multiple_of(5) {
+                        let topo = topology::worker_topology(&stats);
+                        if let Ok(tjson) = serde_json::to_string(&topo)
+                            && tx.send(format_sse("topology", &tjson)).await.is_err() {
+                                return;
+                            }
+                    }
+                } else if let Some(stats) = maybe_pushed {
+                    // No live runtime: serve externally pushed stats (e.g. a
+                    // datastream source). These already carry full actor_details,
+                    // so no collector/name enrichment is needed.
+                    state.history.record(&stats);
+
+                    let warnings = warning_detector.check(&stats);
+                    if !warnings.is_empty()
+                        && let Ok(wjson) = serde_json::to_string(&warnings)
+                            && tx.send(format_sse("warnings", &wjson)).await.is_err() {
+                                return;
+                            }
+
+                    let json = serde_json::to_string(&stats).unwrap();
+                    if tx.send(format_sse("stats", &json)).await.is_err() {
+                        return;
+                    }
+
                     tick_count += 1;
                     if tick_count.is_multiple_of(5) {
                         let topo = topology::worker_topology(&stats);
diff --git a/crates/distribution/DESIGN_NOTES.md b/crates/distribution/DESIGN_NOTES.md
deleted file mode 100644
index 1369e9f..0000000
--- a/crates/distribution/DESIGN_NOTES.md
+++ /dev/null
@@ -1,49 +0,0 @@
-# Distribution Crate — Design Notes
-
-Design decisions behind non-obvious mechanisms in the distribution crate.
-
----
-
-## Transmit Budget (dissemination.rs)
-
-The transmit budget controls how many times a membership update gets piggybacked onto
-protocol messages before being evicted from the dissemination queue.
-
-It is computed as **`Λ * ceil(log₂(n))`** where `Λ` (lambda) is a configurable multiplier
-and `n` is the cluster size. The logarithmic scaling ensures that in a 10-node cluster
-each update is sent ~4Λ times, while in a 1000-node cluster it gets ~10Λ sends — enough
-redundancy for epidemic-style convergence without flooding the network.
-
-Each time an update is piggybacked onto a Ping or Ack message, its remaining budget
-decrements by 1. When the budget reaches zero the update is evicted from the queue.
-Higher-priority updates (e.g. deaths) are piggybacked first, so critical state changes
-propagate faster than routine alive announcements.
-
-## Re-Replication (kademlia/repair.rs — RepairQueue)
-
-In the Kademlia directory, each actor's location entry is STOREd on the `r` closest nodes
-(by XOR distance to the actor address). When one of those replica holders dies, the
-replication factor drops below `r`.
-
-**Re-replication** restores the target replication factor: surviving nodes that detect the
-death extract all directory entries the dead node held and re-STORE them on the
-next-closest node that didn't already have a copy.
-
-In practice: `RepairQueue::on_node_death()` pulls all entries authored by the dead node
-from the local `DirectoryShard` and queues them. The node's tick loop drains the queue
-and issues STORE RPCs to the new r-closest nodes, restoring the replication invariant.
-
-## Periodic Republish (kademlia/repair.rs — RepublishTracker)
-
-Topology churn — nodes joining and leaving — gradually shifts which nodes are "r-closest"
-to a given actor address in XOR space. Without periodic republishing:
-
-- A new node that joins *closer* to an actor than existing replicas would never learn
-  about that actor's entry.
-- Entries could become stranded on nodes that are no longer among the closest, making
-  lookups slower or requiring more hops.
-
-`RepublishTracker` has each node periodically re-STORE the directory entries for its own
-locally-spawned actors at a configurable interval. This ensures entries migrate to the
-current r-closest nodes as the topology evolves, without waiting for a failure event to
-trigger repair.
diff --git a/crates/distribution/src/datastream/catalog.rs b/crates/distribution/src/datastream/catalog.rs
new file mode 100644
index 0000000..1875d51
--- /dev/null
+++ b/crates/distribution/src/datastream/catalog.rs
@@ -0,0 +1,226 @@
+//! The channel catalog (spec §6): the kinds of observation the datastream
+//! carries, as channels, plus the codecs that interpret typed channels.
+//!
+//! This is the schema contract between producers and views. The *pipe*
+//! never consults it — only producers (to tag bytes) and views (to decode)
+//! do. Adding a channel here, or teaching a view a new codec, changes
+//! nothing in the mux, transport, ingest, or store (spec §6.3, §9.3).
+//!
+//! Typed channels use JSON as their codec. JSON is forgiving by design:
+//! decoding ignores unknown fields and `#[serde(default)]` fills missing
+//! ones, so a producer and a consumer can evolve a record independently
+//! (spec §6.3 version skew). A typed channel decodes to a record; a
+//! raw-text channel's "codec" is the identity and a view treats it as
+//! lines (spec §4.2).
+
+use serde::{Deserialize, Serialize};
+
+use super::frame::ChannelId;
+
+// ── Typed channel ids (spec §6.1) ──────────────────────────────────────
+//
+// Each is a stable token. They are `&'static str` constants, not an enum,
+// so that "unknown channel" is simply "an id with no entry here" and a
+// newer producer's channel still lands whole in the store (spec §6.3).
+
+/// Identity / boot — emitted first in a stream; identifies the node and
+/// its context so the consumer can attribute the stream. Event-driven.
+pub const IDENTITY: &str = "identity";
+/// Host / resource samples — periodic snapshots of machine resources.
+pub const HOST_RESOURCE: &str = "host.resource";
+/// Transport internals — the node's connectivity to peers and the relay.
+pub const TRANSPORT_INTERNALS: &str = "transport.internals";
+/// Membership / liveness — the node's view of which peers are alive,
+/// suspect, or dead, and transitions thereof. Event-driven.
+pub const MEMBERSHIP: &str = "membership";
+/// Runtime stats — the node's own actor-runtime metrics. Periodic.
+pub const RUNTIME_STATS: &str = "runtime.stats";
+/// Provider / lifecycle / cost — coarse lifecycle and cost facts about the
+/// node as a rented resource.
+pub const LIFECYCLE_COST: &str = "provider.lifecycle";
+
+/// Which standard stream a span of process output came from (spec §6.2).
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ProcStream {
+    Stdout,
+    Stderr,
+}
+
+impl ProcStream {
+    fn as_str(self) -> &'static str {
+        match self {
+            ProcStream::Stdout => "stdout",
+            ProcStream::Stderr => "stderr",
+        }
+    }
+}
+
+/// A raw-text process-output channel (spec §6.2). This is a *family*
+/// parameterized by process label and stream, so managing a new process
+/// introduces channels without defining new channel *types*:
+/// `proc.<label>.stdout` / `proc.<label>.stderr`.
+pub fn process_output(label: &str, stream: ProcStream) -> ChannelId {
+    ChannelId::new(format!("proc.{label}.{}", stream.as_str()))
+}
+
+/// How a view should treat a channel's bytes, decided by the catalog at
+/// read time. An id the catalog does not know is [`ChannelKind::Opaque`]
+/// and degrades to raw bytes (spec §6.3, §9.3).
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ChannelKind {
+    /// Decodes to a structured record under a JSON codec.
+    Typed,
+    /// Opaque text; a view treats it as lines.
+    Text,
+    /// Unknown to this consumer; retained and shown as raw bytes.
+    Opaque,
+}
+
+/// Classify a channel id. Known typed ids and the `proc.*` text family are
+/// recognized; everything else is [`ChannelKind::Opaque`].
+pub fn classify(channel: &ChannelId) -> ChannelKind {
+    let id = channel.as_str();
+    match id {
+        IDENTITY | HOST_RESOURCE | TRANSPORT_INTERNALS | MEMBERSHIP | RUNTIME_STATS
+        | LIFECYCLE_COST => ChannelKind::Typed,
+        _ if id.starts_with("proc.") => ChannelKind::Text,
+        _ => ChannelKind::Opaque,
+    }
+}
+
+// ── Typed records (realistic shapes for spec §6.1 channels) ────────────
+//
+// These define the bytes a producer actually emits and a metric view
+// actually decodes. They carry `#[serde(default)]` so a missing field
+// decodes to a default (version skew, spec §6.3). Unknown fields are
+// ignored by serde_json on decode for the same reason.
+
+/// A typed channel record: a record knows its own channel and round-trips
+/// through the JSON codec. `decode(encode(r)) == r` is the codec contract
+/// (testing spec §3, §5).
+pub trait Record: Serialize + for<'de> Deserialize<'de> + Sized {
+    /// The channel this record is carried on.
+    const CHANNEL: &'static str;
+
+    /// The channel id this record is carried on.
+    fn channel() -> ChannelId {
+        ChannelId::new(Self::CHANNEL)
+    }
+
+    /// Encode this record to its opaque payload bytes.
+    fn encode(&self) -> Vec<u8> {
+        // Records are plain data; JSON serialization of them cannot fail.
+        serde_json::to_vec(self).expect("record serializes to JSON")
+    }
+
+    /// Decode a payload back into the record. Fails (gracefully) if the
+    /// bytes are not this record's shape — a view degrades to raw bytes
+    /// (spec §9.3) rather than propagating the error.
+    fn decode(payload: &[u8]) -> Result<Self, serde_json::Error> {
+        serde_json::from_slice(payload)
+    }
+}
+
+/// The node's coarse role in the fleet.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum Role {
+    Worker,
+    Coordinator,
+    Relay,
+}
+
+/// Identity / boot record (spec §6.1).
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct IdentityRecord {
+    pub node: String,
+    pub role: Role,
+    pub region: String,
+    /// The lifetime this stream belongs to (spec §8.4), echoed in-band so a
+    /// view can confirm attribution.
+    #[serde(default)]
+    pub life: u64,
+}
+
+/// Host / resource sample (spec §6.1). The metric projection (spec §9.2)
+/// decodes a series of these.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct ResourceSample {
+    #[serde(default)]
+    pub cpu_pct: f32,
+    #[serde(default)]
+    pub mem_used_mb: u32,
+    #[serde(default)]
+    pub mem_total_mb: u32,
+    #[serde(default)]
+    pub gpu_pct: f32,
+    #[serde(default)]
+    pub disk_used_gb: u32,
+    #[serde(default)]
+    pub net_rx_kbps: u32,
+    #[serde(default)]
+    pub net_tx_kbps: u32,
+}
+
+/// Transport-internals record (spec §6.1).
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct TransportInternals {
+    #[serde(default)]
+    pub relay_connected: bool,
+    #[serde(default)]
+    pub direct_peers: u32,
+    #[serde(default)]
+    pub relay_peers: u32,
+    #[serde(default)]
+    pub rtt_ms_p50: u32,
+}
+
+/// Membership / liveness transition (spec §6.1).
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct MembershipTransition {
+    pub peer: String,
+    pub from: String,
+    pub to: String,
+    #[serde(default)]
+    pub reason: String,
+}
+
+/// Runtime-stats record (spec §6.1).
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct RuntimeStats {
+    #[serde(default)]
+    pub actors_live: u32,
+    #[serde(default)]
+    pub mailbox_depth: u32,
+    #[serde(default)]
+    pub scheduled_tasks: u32,
+}
+
+/// Provider / lifecycle / cost record (spec §6.1).
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct LifecycleCost {
+    pub phase: String,
+    #[serde(default)]
+    pub cost_usd_per_hr: f32,
+    #[serde(default)]
+    pub uptime_s: u64,
+}
+
+impl Record for IdentityRecord {
+    const CHANNEL: &'static str = IDENTITY;
+}
+impl Record for ResourceSample {
+    const CHANNEL: &'static str = HOST_RESOURCE;
+}
+impl Record for TransportInternals {
+    const CHANNEL: &'static str = TRANSPORT_INTERNALS;
+}
+impl Record for MembershipTransition {
+    const CHANNEL: &'static str = MEMBERSHIP;
+}
+impl Record for RuntimeStats {
+    const CHANNEL: &'static str = RUNTIME_STATS;
+}
+impl Record for LifecycleCost {
+    const CHANNEL: &'static str = LIFECYCLE_COST;
+}
diff --git a/crates/distribution/src/datastream/frame.rs b/crates/distribution/src/datastream/frame.rs
new file mode 100644
index 0000000..a148d4b
--- /dev/null
+++ b/crates/distribution/src/datastream/frame.rs
@@ -0,0 +1,191 @@
+//! Core data model: the framed, channel-multiplexed stream (spec §4).
+//!
+//! These are the values that ride the seams a test observes (testing spec
+//! §2): a [`Frame`] crosses the mux→transport boundary, and a [`StreamId`]
+//! keys the reconstructed stream at ingest. Everything here is a plain
+//! value type with no behavior — the behavior lives in the mux, ingest,
+//! store, and views.
+
+use std::fmt;
+use std::sync::Arc;
+
+/// A position assigned by a node's mux (spec §5.2).
+///
+/// Positions are **monotonic** and **gap-free** within a single node's
+/// stream: the mux never reuses one and never skips one in its numbering.
+/// A position that is assigned but never delivered surfaces downstream as
+/// a missing position — a detectable gap (spec §5.3, §7.5).
+///
+/// Across nodes, positions are **not** comparable (spec §4.3): they order
+/// frames within one node only.
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+pub struct Position(pub u64);
+
+impl fmt::Display for Position {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
+/// The stable identity of a channel — the named lane a frame's bytes
+/// belong to (spec §4.2, §3).
+///
+/// It is an opaque token: the pipe (mux, transport, ingest, store) never
+/// interprets it. Only a *view* resolves it, through the catalog
+/// ([`crate::datastream::catalog`]), into a codec. A token with no
+/// registered codec is still carried and stored whole, then decoded later
+/// (spec §6.3) — which is why this type is open (any string) rather than a
+/// closed enum: a new channel is a new id, no pipe code changes.
+#[derive(Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub struct ChannelId(Arc<str>);
+
+impl ChannelId {
+    /// Construct a channel id from any string-like value.
+    pub fn new(id: impl AsRef<str>) -> Self {
+        ChannelId(Arc::from(id.as_ref()))
+    }
+
+    /// The id as a string slice.
+    pub fn as_str(&self) -> &str {
+        &self.0
+    }
+}
+
+impl From<&str> for ChannelId {
+    fn from(s: &str) -> Self {
+        ChannelId::new(s)
+    }
+}
+
+impl From<String> for ChannelId {
+    fn from(s: String) -> Self {
+        ChannelId::new(s)
+    }
+}
+
+impl fmt::Display for ChannelId {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(&self.0)
+    }
+}
+
+impl fmt::Debug for ChannelId {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "ChannelId({:?})", &self.0)
+    }
+}
+
+/// The stable identity of a node that produces a stream (spec §4.4, §8.1).
+///
+/// Opaque to the pipe. In a deployment this is whatever durable id the
+/// system already assigns a machine (e.g. its public key); tests use
+/// readable names. A frame records the producing *node*, never a producer
+/// identity within it (spec §4.4).
+#[derive(Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub struct NodeId(Arc<str>);
+
+impl NodeId {
+    /// Construct a node id from any string-like value.
+    pub fn new(id: impl AsRef<str>) -> Self {
+        NodeId(Arc::from(id.as_ref()))
+    }
+
+    /// The id as a string slice.
+    pub fn as_str(&self) -> &str {
+        &self.0
+    }
+}
+
+impl From<&str> for NodeId {
+    fn from(s: &str) -> Self {
+        NodeId::new(s)
+    }
+}
+
+impl fmt::Display for NodeId {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(&self.0)
+    }
+}
+
+impl fmt::Debug for NodeId {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "NodeId({:?})", &self.0)
+    }
+}
+
+/// A lifetime discriminator distinguishing a node's incarnations (spec
+/// §8.4). A node that dies and is re-rented starts a new lifetime, so its
+/// fresh stream does not collide with or append to its prior life.
+#[derive(Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord, Debug)]
+pub struct Lifetime(pub u64);
+
+/// Identifies exactly one stored stream: a node plus the life it was
+/// produced in (spec §8.4).
+///
+/// This is the ingest key. Two streams with the same [`NodeId`] but
+/// different [`Lifetime`] are different streams and MUST NOT merge — that
+/// is what lets a re-incarnated node not append to its prior life.
+#[derive(Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Debug)]
+pub struct StreamId {
+    /// Which node produced the stream.
+    pub node: NodeId,
+    /// Which life of that node.
+    pub life: Lifetime,
+}
+
+impl StreamId {
+    /// Construct a stream id from a node and a lifetime.
+    pub fn new(node: impl Into<NodeId>, life: Lifetime) -> Self {
+        StreamId { node: node.into(), life }
+    }
+}
+
+impl fmt::Display for StreamId {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}#{}", self.node, self.life.0)
+    }
+}
+
+/// The unit the mux emits (spec §4.1): bytes tagged with a channel and a
+/// position.
+///
+/// The `payload` is **opaque** to everything between the producer and a
+/// view — the mux, the transport, and storage treat it as bytes and never
+/// interpret it (spec §4.1). A typed event and a log line are the same
+/// kind of thing here: bytes on a channel.
+///
+/// Per the `// USER:` annotation on spec §4.1/§5.2 there is no per-frame
+/// wall-clock timestamp: frames are ordered and correlated by position
+/// alone.
+#[derive(Clone, PartialEq, Eq)]
+pub struct Frame {
+    /// The lane these bytes belong to.
+    pub channel: ChannelId,
+    /// The mux-assigned position within the node's stream.
+    pub position: Position,
+    /// The opaque payload bytes.
+    pub payload: Vec<u8>,
+}
+
+impl Frame {
+    /// Assemble a frame from its parts.
+    pub fn new(channel: impl Into<ChannelId>, position: Position, payload: Vec<u8>) -> Self {
+        Frame { channel: channel.into(), position, payload }
+    }
+}
+
+impl fmt::Debug for Frame {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        // Render the payload as text when it is valid UTF-8 (log lines,
+        // JSON records both are) so debug output is readable; fall back to
+        // a byte count for genuinely binary payloads.
+        let mut dbg = f.debug_struct("Frame");
+        dbg.field("channel", &self.channel).field("position", &self.position);
+        match std::str::from_utf8(&self.payload) {
+            Ok(text) => dbg.field("payload", &text),
+            Err(_) => dbg.field("payload", &format_args!("<{} bytes>", self.payload.len())),
+        };
+        dbg.finish()
+    }
+}
diff --git a/crates/distribution/src/datastream/ingest.rs b/crates/distribution/src/datastream/ingest.rs
new file mode 100644
index 0000000..a86979d
--- /dev/null
+++ b/crates/distribution/src/datastream/ingest.rs
@@ -0,0 +1,58 @@
+//! Consumer ingest: reconstruct each node's stream from deliveries (spec
+//! §8.1).
+//!
+//! The consumer receives frames from many nodes, in any order, some never
+//! arriving, and reconstructs each node's stream — keyed by stream id,
+//! ordered by position — into the [`Store`]. Ingest is deliberately thin:
+//! it routes a delivery to its stream and records the frame whole. It MUST
+//! NOT thin, aggregate, decode-and-discard, or truncate (spec §8.2), and it
+//! never inspects a channel or a payload, so a channel it cannot decode is
+//! retained exactly like any other (spec §8.3).
+//!
+//! Reconstruction is by position, not arrival: out-of-order deliveries land
+//! in order in the store, and a position delivered twice collapses to one
+//! (spec §7.5). Two lives of one node are different stream ids and never
+//! merge (spec §8.4).
+
+use super::store::Store;
+use super::transport::Delivery;
+
+/// The single consumer toward which all telemetry flows (spec §2). It owns
+/// the stored streams and grows them as deliveries arrive.
+#[derive(Debug, Default)]
+pub struct Consumer {
+    store: Store,
+}
+
+impl Consumer {
+    /// A consumer with an empty store.
+    pub fn new() -> Self {
+        Consumer::default()
+    }
+
+    /// Accept one delivery: route it to its stream and record the frame.
+    /// Returns `true` if the frame was new (a duplicate position is
+    /// ignored, keeping the first — the carrier cannot fabricate content,
+    /// spec §9).
+    pub fn accept(&mut self, delivery: Delivery) -> bool {
+        let Delivery { stream, frame } = delivery;
+        self.store.stream_mut(&stream).record(frame)
+    }
+
+    /// Accept a batch of deliveries, in whatever order they arrive.
+    pub fn ingest(&mut self, deliveries: impl IntoIterator<Item = Delivery>) {
+        for delivery in deliveries {
+            self.accept(delivery);
+        }
+    }
+
+    /// The stored streams — the source of truth for every view (spec §8.2).
+    pub fn store(&self) -> &Store {
+        &self.store
+    }
+
+    /// Consume the consumer, yielding its store.
+    pub fn into_store(self) -> Store {
+        self.store
+    }
+}
diff --git a/crates/distribution/src/datastream/mod.rs b/crates/distribution/src/datastream/mod.rs
new file mode 100644
index 0000000..7dfe997
--- /dev/null
+++ b/crates/distribution/src/datastream/mod.rs
@@ -0,0 +1,49 @@
+//! The per-node telemetry **datastream** (see `DATASTREAM_SPEC.md`).
+//!
+//! A deliberately dumb pipe: producers dump bytes tagged by channel, a
+//! single per-node mux interleaves them into one ordered stream, a
+//! best-effort transport carries that stream to the one consumer, ingest
+//! reconstructs each node's stream by position, and views are read-time
+//! projections over the stored stream. Nothing between a producer and a
+//! view interprets the payload.
+//!
+//! ```text
+//!    producers (typed + text)
+//!             │  bytes tagged by channel        → [`catalog`]
+//!             ▼
+//!         per-node MUX                          → [`mux::Mux`]
+//!             │  one ordered stream of [`Frame`]s
+//!             ▼
+//!    best-effort transport                      → [`transport`]
+//!             │  delivery: frames, maybe dropped/reordered/delayed
+//!             ▼
+//!       consumer INGEST                         → [`ingest::Consumer`]
+//!             │  complete stream, stored whole
+//!             ▼
+//!      stored STREAM (truth)                    → [`store`]
+//!             │  read-time only
+//!             ▼
+//!         VIEWS                                 → [`views`]
+//! ```
+//!
+//! The data model ([`frame`]) and the wire envelope ([`wire`]) are the
+//! seams a test observes; the catalog ([`catalog`]) is the schema contract
+//! between producers and views. See `DATASTREAM_TESTING_SPEC.md` for how
+//! the pipe is verified.
+
+pub mod catalog;
+pub mod frame;
+pub mod ingest;
+pub mod mux;
+pub mod source;
+pub mod store;
+pub mod transport;
+pub mod views;
+pub mod wire;
+
+pub use frame::{ChannelId, Frame, Lifetime, NodeId, Position, StreamId};
+pub use ingest::Consumer;
+pub use mux::Mux;
+pub use store::{GapSpan, Store, StoredStream};
+pub use transport::{Delivery, Reorder, ScriptedTransport, StreamScript};
+pub use views::{Body, LogEntry, MergedFrame};
diff --git a/crates/distribution/src/datastream/mux.rs b/crates/distribution/src/datastream/mux.rs
new file mode 100644
index 0000000..9713219
--- /dev/null
+++ b/crates/distribution/src/datastream/mux.rs
@@ -0,0 +1,111 @@
+//! The per-node mux: the single ordering authority (spec §5).
+//!
+//! Every producer on a node submits its bytes — tagged with a channel — to
+//! one mux, and the mux interleaves them into the node's single ordered
+//! stream. Because all channels pass through one assigner, a structured
+//! event and a log line emitted close together have a well-defined relative
+//! order (spec §5.1): that is what makes the one-timeline guarantee real.
+//!
+//! Two invariants do the heavy lifting:
+//!
+//! * **Gap-free, monotonic numbering** (spec §5.2). The mux hands out
+//!   positions `0, 1, 2, …` with an atomic counter — never reused, never
+//!   skipped. Numbering is independent of delivery: assigning a position
+//!   does not mean the frame is, or ever will be, delivered.
+//! * **A drop is a missing position, never a renumber** (spec §5.3). The
+//!   mux buffers within a bound to smooth bursts; on overflow it drops the
+//!   frame. But the position was already consumed, so the drop surfaces
+//!   downstream as a detectable gap (spec §7.5) rather than a silent
+//!   renumbering.
+//!
+//! Submission is non-blocking in spirit: the only shared section is an
+//! O(1) counter bump and a push onto a bounded queue, so telemetry never
+//! stalls the node's real work (spec §5.3).
+
+use std::collections::VecDeque;
+use std::sync::Mutex;
+use std::sync::atomic::{AtomicU64, Ordering};
+
+use super::frame::{ChannelId, Frame, Position, StreamId};
+
+/// A node's single position authority and outgoing telemetry buffer.
+///
+/// One mux belongs to one stream — one life of one node (spec §8.4). It is
+/// `Send + Sync`: producers on different threads may submit concurrently
+/// and the mux serializes them into one position order (spec §5.3).
+pub struct Mux {
+    stream: StreamId,
+    next: AtomicU64,
+    dropped: AtomicU64,
+    capacity: usize,
+    buffer: Mutex<VecDeque<Frame>>,
+}
+
+impl Mux {
+    /// Create a mux for `stream` with a bounded outgoing buffer. When more
+    /// than `capacity` frames are waiting to be drained, further
+    /// submissions are dropped (spec §5.3) — but still consume a position.
+    pub fn new(stream: StreamId, capacity: usize) -> Self {
+        Mux {
+            stream,
+            next: AtomicU64::new(0),
+            dropped: AtomicU64::new(0),
+            capacity,
+            buffer: Mutex::new(VecDeque::new()),
+        }
+    }
+
+    /// Create a mux whose buffer never overflows. Useful when a caller
+    /// drains promptly and wants every assigned frame retained.
+    pub fn unbounded(stream: StreamId) -> Self {
+        Mux::new(stream, usize::MAX)
+    }
+
+    /// The stream this mux produces (spec §8.4 ingest key).
+    pub fn stream_id(&self) -> &StreamId {
+        &self.stream
+    }
+
+    /// Submit opaque bytes on a channel. Assigns and returns the next
+    /// position. The frame is buffered for the transport to drain, or
+    /// dropped on overflow — either way the returned position is consumed,
+    /// so a drop becomes a missing position downstream (spec §5.3).
+    ///
+    /// The mux never inspects `payload`; it is opaque (spec §4.1).
+    pub fn submit(&self, channel: impl Into<ChannelId>, payload: Vec<u8>) -> Position {
+        // Assign first, unconditionally: numbering is independent of
+        // whether the frame survives the buffer (spec §5.2).
+        let position = Position(self.next.fetch_add(1, Ordering::Relaxed));
+        let frame = Frame { channel: channel.into(), position, payload };
+
+        let mut buffer = self.buffer.lock().expect("mux buffer poisoned");
+        if buffer.len() < self.capacity {
+            buffer.push_back(frame);
+        } else {
+            // Overflow: drop the frame that does not fit. Its position is
+            // already spent, so it will read as a gap, not a renumber.
+            self.dropped.fetch_add(1, Ordering::Relaxed);
+        }
+        position
+    }
+
+    /// Pull all currently buffered frames, in the order they were buffered,
+    /// emptying the buffer. The transport drains the mux's outgoing stream
+    /// this way.
+    pub fn drain(&self) -> Vec<Frame> {
+        let mut buffer = self.buffer.lock().expect("mux buffer poisoned");
+        buffer.drain(..).collect()
+    }
+
+    /// How many positions have been assigned — the gap-free high-water mark
+    /// (spec §5.2). Equal to the number of `submit` calls.
+    pub fn assigned(&self) -> u64 {
+        self.next.load(Ordering::Relaxed)
+    }
+
+    /// How many frames have been dropped on overflow (spec §5.3). Each
+    /// dropped frame is one missing position downstream.
+    pub fn dropped(&self) -> u64 {
+        self.dropped.load(Ordering::Relaxed)
+    }
+}
diff --git a/crates/distribution/src/datastream/source.rs b/crates/distribution/src/datastream/source.rs
new file mode 100644
index 0000000..9ef6764
--- /dev/null
+++ b/crates/distribution/src/datastream/source.rs
@@ -0,0 +1,216 @@
+//! Producer-side helpers: map a node's live state into the typed records of
+//! the [`catalog`](super::catalog).
+//!
+//! These turn data the node already has — host counters, a runtime-stats
+//! snapshot, the membership view — into the records a producer submits to its
+//! mux. Nothing here touches the pipe; it is pure "live state in, record out"
+//! so it can be unit-tested without a transport, and it deliberately carries
+//! no dependency on the cluster transport (iroh) so it builds with any feature
+//! set.
+
+use std::collections::HashMap;
+use std::time::Instant;
+
+use super::catalog::{IdentityRecord, MembershipTransition, ResourceSample, Role};
+
+/// Build the identity record a node emits first on its stream (spec §6.1).
+pub fn identity_record(node: &str, role: Role, region: &str, life: u64) -> IdentityRecord {
+    IdentityRecord {
+        node: node.to_string(),
+        role,
+        region: region.to_string(),
+        life,
+    }
+}
+
+/// Samples host CPU usage across calls. CPU percent is a rate, so it needs two
+/// observations to compute; the first call seeds the baseline and reports 0.
+#[derive(Default)]
+pub struct CpuSampler {
+    prev: Option<(u64, Instant)>,
+}
+
+impl CpuSampler {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// CPU busy percent since the previous call, in `[0, 100*ncpu]` clamped to
+    /// `[0, 100]`. Returns 0 on the first call (no baseline yet) and on any
+    /// platform where `/proc/stat` is unavailable.
+    pub fn sample(&mut self) -> f32 {
+        let now = Instant::now();
+        let busy = match read_proc_stat_busy_jiffies() {
+            Some(j) => j,
+            None => return 0.0,
+        };
+        let pct = match self.prev {
+            Some((prev_busy, prev_at)) => {
+                let elapsed = now.duration_since(prev_at).as_secs_f64();
+                if elapsed <= 0.0 {
+                    0.0
+                } else {
+                    // Jiffies are USER_HZ (typically 100/s) per CPU. Normalize by
+                    // wall time and the tick rate to get a busy fraction.
+                    let delta = busy.saturating_sub(prev_busy) as f64;
+                    let hz = clock_ticks_per_sec();
+                    let frac = delta / (hz * elapsed);
+                    (frac * 100.0).clamp(0.0, 100.0) as f32
+                }
+            }
+            None => 0.0,
+        };
+        self.prev = Some((busy, now));
+        pct
+    }
+}
+
+/// Read a host-resource sample: CPU busy percent (via `sampler`) and memory
+/// from `/proc/meminfo`. Fields we have no source for stay at their default
+/// (honest zeros), and on a non-Linux host the whole sample is the default.
+pub fn read_host_resource(sampler: &mut CpuSampler) -> ResourceSample {
+    let cpu_pct = sampler.sample();
+    let (mem_total_mb, mem_used_mb) = read_meminfo_mb().unwrap_or((0, 0));
+    // Fields we have no host source for stay at honest zeros.
+    ResourceSample {
+        cpu_pct,
+        mem_used_mb,
+        mem_total_mb,
+        gpu_pct: 0.0,
+        disk_used_gb: 0,
+        net_rx_kbps: 0,
+        net_tx_kbps: 0,
+    }
+}
+
+/// Tracks the last-seen membership state per peer and emits a transition only
+/// when a peer's state changes — membership is an event-driven channel
+/// (spec §6.1), so a steady cluster produces no frames.
+#[derive(Default)]
+pub struct MembershipTracker {
+    last: HashMap<String, String>,
+}
+
+impl MembershipTracker {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Diff the current `(peer, state)` view against the last one. A newly seen
+    /// peer transitions from `"unknown"`; a peer whose state is unchanged
+    /// produces nothing.
+    pub fn diff(&mut self, members: &[(String, String)]) -> Vec<MembershipTransition> {
+        let mut out = Vec::new();
+        for (peer, state) in members {
+            let changed = match self.last.get(peer) {
+                Some(prev) => prev != state,
+                None => true,
+            };
+            if changed {
+                let from = self
+                    .last
+                    .get(peer)
+                    .cloned()
+                    .unwrap_or_else(|| "unknown".to_string());
+                out.push(MembershipTransition {
+                    peer: peer.clone(),
+                    from,
+                    to: state.clone(),
+                    reason: String::new(),
+                });
+                self.last.insert(peer.clone(), state.clone());
+            }
+        }
+        out
+    }
+}
+
+// ── Host counters (Linux /proc) ────────────────────────────────────────────
+
+fn clock_ticks_per_sec() -> f64 {
+    #[cfg(target_os = "linux")]
+    {
+        // SAFETY: sysconf is a pure lookup with no preconditions.
+        let hz = unsafe { libc::sysconf(libc::_SC_CLK_TCK) };
+        if hz > 0 {
+            return hz as f64;
+        }
+    }
+    100.0
+}
+
+/// Total non-idle jiffies from the aggregate `cpu` line of `/proc/stat`.
+fn read_proc_stat_busy_jiffies() -> Option<u64> {
+    let text = std::fs::read_to_string("/proc/stat").ok()?;
+    let line = text.lines().next()?; // the aggregate "cpu  ..." line
+    let mut it = line.split_whitespace();
+    if it.next()? != "cpu" {
+        return None;
+    }
+    // user nice system idle iowait irq softirq steal guest guest_nice
+    let vals: Vec<u64> = it.filter_map(|t| t.parse::<u64>().ok()).collect();
+    if vals.len() < 4 {
+        return None;
+    }
+    let total: u64 = vals.iter().sum();
+    let idle = vals[3] + vals.get(4).copied().unwrap_or(0); // idle + iowait
+    Some(total.saturating_sub(idle))
+}
+
+/// `(MemTotal, MemTotal - MemAvailable)` in MiB from `/proc/meminfo`.
+fn read_meminfo_mb() -> Option<(u32, u32)> {
+    let text = std::fs::read_to_string("/proc/meminfo").ok()?;
+    let mut total_kb = None;
+    let mut avail_kb = None;
+    for line in text.lines() {
+        if let Some(rest) = line.strip_prefix("MemTotal:") {
+            total_kb = rest.split_whitespace().next().and_then(|v| v.parse::<u64>().ok());
+        } else if let Some(rest) = line.strip_prefix("MemAvailable:") {
+            avail_kb = rest.split_whitespace().next().and_then(|v| v.parse::<u64>().ok());
+        }
+    }
+    let total = total_kb?;
+    let avail = avail_kb.unwrap_or(total);
+    let used = total.saturating_sub(avail);
+    Some(((total / 1024) as u32, (used / 1024) as u32))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    #[cfg_attr(not(target_os = "linux"), ignore)]
+    fn host_resource_reports_real_memory_on_linux() {
+        // On a real Linux host the machine has some memory; a sample that
+        // reported zero total would mean we never read the host at all.
+        let mut sampler = CpuSampler::new();
+        let sample = read_host_resource(&mut sampler);
+        assert!(sample.mem_total_mb > 0, "expected to read MemTotal from the host");
+        assert!(
+            sample.mem_used_mb <= sample.mem_total_mb,
+            "used memory cannot exceed total"
+        );
+    }
+
+    #[test]
+    fn membership_emits_only_when_a_peer_changes_state() {
+        let mut tracker = MembershipTracker::new();
+
+        // First sighting of a peer is a transition from the unknown state.
+        let first = tracker.diff(&[("peer-a".into(), "alive".into())]);
+        assert_eq!(first.len(), 1);
+        assert_eq!(first[0].from, "unknown");
+        assert_eq!(first[0].to, "alive");
+
+        // Re-reporting the same state is silence — a steady cluster is quiet.
+        let steady = tracker.diff(&[("peer-a".into(), "alive".into())]);
+        assert!(steady.is_empty(), "no transition when nothing changed");
+
+        // A genuine state change surfaces, carrying the prior state.
+        let changed = tracker.diff(&[("peer-a".into(), "suspect".into())]);
+        assert_eq!(changed.len(), 1);
+        assert_eq!(changed[0].from, "alive");
+        assert_eq!(changed[0].to, "suspect");
+    }
+}
diff --git a/crates/distribution/src/datastream/store.rs b/crates/distribution/src/datastream/store.rs
new file mode 100644
index 0000000..7078dfa
--- /dev/null
+++ b/crates/distribution/src/datastream/store.rs
@@ -0,0 +1,160 @@
+//! The stored stream — the consumer's source of truth (spec §8).
+//!
+//! Storage holds each node's **complete** stream, whole and append-only.
+//! Nothing is thinned, aggregated, decoded-and-discarded, or truncated at
+//! ingest (spec §8.2); everything a view ever shows is derived from here
+//! (spec §9.1). Frames on channels the consumer cannot decode are kept as
+//! opaque bytes, in order, alongside the rest (spec §8.3) — the store never
+//! looks at a channel or a payload.
+//!
+//! A [`StoredStream`] is keyed in the [`Store`] by [`StreamId`] — node plus
+//! lifetime — so a re-incarnated node does not append to its prior life
+//! (spec §8.4).
+
+use std::collections::BTreeMap;
+
+use super::frame::{Frame, Position, StreamId};
+
+/// One node's reconstructed stream: its frames in position order, whole.
+///
+/// Backed by a position-keyed map so out-of-order arrivals land in order
+/// and a position seen twice collapses to one (the carrier may not
+/// fabricate content, spec §9). Gaps are not stored — they are *derived*
+/// at read time from the positions that are present (spec §9.1).
+#[derive(Debug, Clone, Default)]
+pub struct StoredStream {
+    frames: BTreeMap<u64, Frame>,
+}
+
+impl StoredStream {
+    /// An empty stream.
+    pub fn new() -> Self {
+        StoredStream::default()
+    }
+
+    /// Record a delivered frame. Idempotent by position: the first frame
+    /// seen for a position wins and is never mutated (append-only,
+    /// spec §8.2). Returns `true` if this was the first time the position
+    /// was seen.
+    pub fn record(&mut self, frame: Frame) -> bool {
+        match self.frames.entry(frame.position.0) {
+            std::collections::btree_map::Entry::Vacant(slot) => {
+                slot.insert(frame);
+                true
+            }
+            std::collections::btree_map::Entry::Occupied(_) => false,
+        }
+    }
+
+    /// The stored frames, in position order.
+    pub fn frames(&self) -> impl Iterator<Item = &Frame> {
+        self.frames.values()
+    }
+
+    /// The stored frames cloned into a vector, in position order. Handy for
+    /// asserting against the reference model.
+    pub fn to_vec(&self) -> Vec<Frame> {
+        self.frames.values().cloned().collect()
+    }
+
+    /// How many frames are stored.
+    pub fn len(&self) -> usize {
+        self.frames.len()
+    }
+
+    /// Whether the stream has no frames yet.
+    pub fn is_empty(&self) -> bool {
+        self.frames.is_empty()
+    }
+
+    /// The frame at an exact position, if stored.
+    pub fn at(&self, position: Position) -> Option<&Frame> {
+        self.frames.get(&position.0)
+    }
+
+    /// The **interior** gaps — runs of positions assigned between the first
+    /// and last delivered frame but never delivered (spec §7.5, §8), each as
+    /// one [`GapSpan`].
+    ///
+    /// Cost is O(stored frames), never O(gap size): it walks adjacent stored
+    /// positions and reads each span's endpoints from them, rather than
+    /// enumerating the (possibly enormous) range in between. A stream that
+    /// brackets a huge interior gap — what a long consumer outage produces
+    /// (spec §7.4), or a single wild position from a corrupt datagram — still
+    /// surfaces in work proportional to the frames held, not to `u64::MAX`.
+    ///
+    /// Only interior gaps are knowable: a position lost *after* the last
+    /// delivered frame leaves no bracketing frame to reveal it, so it shows
+    /// up as the stream simply ending (spec §7.4 node death), not a gap.
+    pub fn gap_spans(&self) -> Vec<GapSpan> {
+        let mut spans = Vec::new();
+        let mut prev: Option<u64> = None;
+        for &p in self.frames.keys() {
+            if let Some(q) = prev
+                && p > q + 1
+            {
+                spans.push(GapSpan { start: q + 1, end: p - 1 });
+            }
+            prev = Some(p);
+        }
+        spans
+    }
+}
+
+/// A contiguous run of missing positions surfaced in a stored stream
+/// (spec §7.5). Inclusive on both ends.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct GapSpan {
+    /// First missing position.
+    pub start: u64,
+    /// Last missing position.
+    pub end: u64,
+}
+
+impl GapSpan {
+    /// How many positions the gap spans (always at least one).
+    pub fn count(&self) -> u64 {
+        self.end - self.start + 1
+    }
+}
+
+/// All stored streams at the consumer, keyed by [`StreamId`] (spec §8.4).
+///
+/// Two streams with the same node but different lifetime are distinct keys
+/// and never merge.
+#[derive(Debug, Clone, Default)]
+pub struct Store {
+    streams: BTreeMap<StreamId, StoredStream>,
+}
+
+impl Store {
+    /// An empty store.
+    pub fn new() -> Self {
+        Store::default()
+    }
+
+    /// The stored stream for a node's life, if any frames have landed.
+    pub fn stream(&self, id: &StreamId) -> Option<&StoredStream> {
+        self.streams.get(id)
+    }
+
+    /// The stored stream for a node's life, creating an empty one if needed.
+    pub fn stream_mut(&mut self, id: &StreamId) -> &mut StoredStream {
+        self.streams.entry(id.clone()).or_default()
+    }
+
+    /// Every stream id the store holds, in a stable order.
+    pub fn stream_ids(&self) -> impl Iterator<Item = &StreamId> {
+        self.streams.keys()
+    }
+
+    /// How many distinct streams the store holds.
+    pub fn len(&self) -> usize {
+        self.streams.len()
+    }
+
+    /// Whether the store holds no streams.
+    pub fn is_empty(&self) -> bool {
+        self.streams.is_empty()
+    }
+}
diff --git a/crates/distribution/src/datastream/transport.rs b/crates/distribution/src/datastream/transport.rs
new file mode 100644
index 0000000..6a5d323
--- /dev/null
+++ b/crates/distribution/src/datastream/transport.rs
@@ -0,0 +1,159 @@
+//! Transport: best-effort carriage of a node's stream to the one consumer
+//! (spec §7), and a scripted in-process carrier for offline tests (testing
+//! spec §2, §9).
+//!
+//! A [`Delivery`] is the value on the transport→ingest seam: which stream a
+//! frame belongs to, and the frame. A real carrier rides the connections
+//! the system already maintains (spec §7.1); a test replaces it with the
+//! [`ScriptedTransport`] here, whose faults are chosen by the scenario and
+//! stay inside the **envelope** (testing spec §9): a carrier may *deliver*,
+//! *drop*, *reorder*, or *delay*, and it MUST NOT corrupt a payload,
+//! fabricate a frame, or alter a position.
+//!
+//! Under position-ordering a *delay* is indistinguishable from a *reorder*
+//! (a delayed frame simply arrives later), so the envelope's delay is
+//! covered by [`Reorder`]. Everything the scripted carrier produces is a
+//! reordered subsequence of what was sent — never a superset, never a
+//! mutation — which is exactly the property the real-transport conformance
+//! check pins (testing spec §9).
+
+use std::collections::BTreeSet;
+
+use super::frame::{Frame, StreamId};
+
+/// A frame as the consumer receives it from the transport (testing spec §2
+/// seam): tagged with the stream it belongs to.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Delivery {
+    /// Which node's life produced the frame (spec §8.1 ingest key).
+    pub stream: StreamId,
+    /// The carried frame, its payload and position untouched.
+    pub frame: Frame,
+}
+
+impl Delivery {
+    /// Pair a stream id with a frame.
+    pub fn new(stream: StreamId, frame: Frame) -> Self {
+        Delivery { stream, frame }
+    }
+}
+
+/// How the surviving frames of a stream are reordered on arrival. This is
+/// the envelope's *reorder* (and *delay*) axis (testing spec §9); each
+/// variant is a permutation of the survivors, never adding or dropping.
+#[derive(Debug, Clone, Default)]
+pub enum Reorder {
+    /// Delivered in the order sent.
+    #[default]
+    InOrder,
+    /// Delivered fully reversed — the deepest reorder a stream admits.
+    Reversed,
+    /// Each consecutive run of `width` frames is reversed, bounding how far
+    /// out of order any frame can arrive (reorder depth ≤ `width`).
+    Windows(usize),
+    /// An explicit permutation: `delivered[i] = survivors[indices[i]]`.
+    /// `indices` should be a permutation of `0..survivors.len()`; entries
+    /// out of range are skipped so a mis-authored vector cannot panic.
+    Permutation(Vec<usize>),
+}
+
+/// The faults a scripted carrier applies to one stream (testing spec §9
+/// envelope). Drops and reorders only — payloads and positions are never
+/// touched.
+#[derive(Debug, Clone, Default)]
+pub struct StreamScript {
+    /// Positions the carrier never delivers. This one set expresses a
+    /// single drop, a total-loss span, and a consumer outage alike — every
+    /// position produced during the loss is simply listed here.
+    pub dropped: BTreeSet<u64>,
+    /// How the surviving frames are reordered on arrival.
+    pub reorder: Reorder,
+}
+
+impl StreamScript {
+    /// A clean carrier: deliver everything, in order.
+    pub fn perfect() -> Self {
+        StreamScript::default()
+    }
+
+    /// Drop exactly these positions, otherwise deliver in order.
+    pub fn dropping(positions: impl IntoIterator<Item = u64>) -> Self {
+        StreamScript { dropped: positions.into_iter().collect(), reorder: Reorder::InOrder }
+    }
+
+    /// Set the reorder behavior (builder style).
+    pub fn with_reorder(mut self, reorder: Reorder) -> Self {
+        self.reorder = reorder;
+        self
+    }
+}
+
+/// A scripted, in-process transport (testing spec §2). It is a pure,
+/// deterministic transform from what a node *sent* to what the consumer is
+/// *delivered* — the entanglement of real wires replaced by a script so a
+/// run completes in microseconds and returns the same result every time.
+pub struct ScriptedTransport;
+
+impl ScriptedTransport {
+    /// Carry one node's sent frames to the consumer under `script`,
+    /// returning the deliveries in arrival order. Dropped positions are
+    /// removed; the survivors are reordered; nothing else changes.
+    pub fn carry(stream: &StreamId, sent: &[Frame], script: &StreamScript) -> Vec<Delivery> {
+        let survivors: Vec<Frame> =
+            sent.iter().filter(|f| !script.dropped.contains(&f.position.0)).cloned().collect();
+        let ordered = reorder(survivors, &script.reorder);
+        ordered.into_iter().map(|frame| Delivery::new(stream.clone(), frame)).collect()
+    }
+
+    /// Carry several nodes' streams and interleave their deliveries in a
+    /// fixed round-robin, the way one wire would multiplex many senders.
+    /// Cross-node order is meaningless (spec §4.3); this just proves ingest
+    /// routes by stream id, not by arrival.
+    pub fn carry_all(streams: &[(StreamId, Vec<Frame>, StreamScript)]) -> Vec<Delivery> {
+        let per_stream: Vec<Vec<Delivery>> =
+            streams.iter().map(|(id, sent, script)| Self::carry(id, sent, script)).collect();
+        round_robin(per_stream)
+    }
+}
+
+fn reorder(mut survivors: Vec<Frame>, reorder: &Reorder) -> Vec<Frame> {
+    match reorder {
+        Reorder::InOrder => survivors,
+        Reorder::Reversed => {
+            survivors.reverse();
+            survivors
+        }
+        Reorder::Windows(width) => {
+            let width = (*width).max(1);
+            let mut out = Vec::with_capacity(survivors.len());
+            for chunk in survivors.chunks(width) {
+                out.extend(chunk.iter().rev().cloned());
+            }
+            out
+        }
+        Reorder::Permutation(indices) => indices
+            .iter()
+            .filter_map(|&i| survivors.get(i).cloned())
+            .collect(),
+    }
+}
+
+fn round_robin(mut lists: Vec<Vec<Delivery>>) -> Vec<Delivery> {
+    // Reverse each so we can pop from the back cheaply while preserving the
+    // per-stream arrival order.
+    for list in &mut lists {
+        list.reverse();
+    }
+    let mut out = Vec::new();
+    let mut any = true;
+    while any {
+        any = false;
+        for list in &mut lists {
+            if let Some(d) = list.pop() {
+                out.push(d);
+                any = true;
+            }
+        }
+    }
+    out
+}
diff --git a/crates/distribution/src/datastream/views.rs b/crates/distribution/src/datastream/views.rs
new file mode 100644
index 0000000..3d87c83
--- /dev/null
+++ b/crates/distribution/src/datastream/views.rs
@@ -0,0 +1,177 @@
+//! Views: read-time projections over a stored stream (spec §9).
+//!
+//! Everything a consumer shows is computed here, at read time, from the
+//! stored stream alone (spec §9.1) — nothing is pre-projected at ingest.
+//! That is what lets a merged log, a metric series, a tail/grep, and a
+//! replay all be views of the same complete record. Adding or changing a
+//! view changes nothing in producers, channels, or storage (spec §9.3):
+//! every function here takes only a [`StoredStream`].
+//!
+//! A view decodes a typed channel via its catalog codec; over a channel it
+//! cannot decode — an unknown id, or typed bytes that do not parse — it
+//! **degrades to raw bytes** rather than failing (spec §9.3).
+//!
+//! The four named projections of spec §9.2 are:
+//!
+//! * [`merged_log`] / [`replay`] — the single timeline across all channels,
+//!   in position order, with surfaced gaps;
+//! * [`metric_series`] — decode one typed channel into a time series;
+//! * [`tail`], [`grep`], [`filter`] — windowed / predicate-restricted views.
+
+use std::fmt;
+
+use super::catalog::{self, ChannelKind, Record};
+use super::frame::{ChannelId, Frame, Position};
+use super::store::{GapSpan, StoredStream};
+
+/// One entry on the merged timeline: either a frame or a surfaced gap.
+#[derive(Debug, Clone, PartialEq)]
+pub enum LogEntry {
+    /// A stored frame, its payload decoded for display.
+    Frame(MergedFrame),
+    /// A run of positions that were assigned but never delivered (spec
+    /// §7.5), surfaced rather than silently concatenated across.
+    Gap(GapSpan),
+}
+
+/// A frame as the merged log presents it: where it sits on the timeline,
+/// which channel it came from, and its payload decoded as far as the
+/// catalog allows.
+#[derive(Debug, Clone, PartialEq)]
+pub struct MergedFrame {
+    /// The frame's position on the node's single timeline.
+    pub position: Position,
+    /// The channel the bytes belong to.
+    pub channel: ChannelId,
+    /// The payload, decoded per the channel's codec (or degraded to bytes).
+    pub body: Body,
+}
+
+/// A payload decoded as far as the catalog allows (spec §9.3).
+#[derive(Debug, Clone, PartialEq)]
+pub enum Body {
+    /// A typed channel decoded to a structured value.
+    Record(serde_json::Value),
+    /// A raw-text channel as its line(s).
+    Text(String),
+    /// A channel the consumer cannot decode — an unknown id, or typed bytes
+    /// that failed to parse — kept as raw bytes (graceful degradation).
+    Raw(Vec<u8>),
+}
+
+/// Decode a payload for display, degrading gracefully (spec §9.3): a typed
+/// channel whose bytes do not parse, and any unknown channel, fall back to
+/// raw bytes instead of failing.
+pub fn decode_body(channel: &ChannelId, payload: &[u8]) -> Body {
+    match catalog::classify(channel) {
+        ChannelKind::Typed => match serde_json::from_slice::<serde_json::Value>(payload) {
+            Ok(value) => Body::Record(value),
+            Err(_) => Body::Raw(payload.to_vec()),
+        },
+        ChannelKind::Text => match std::str::from_utf8(payload) {
+            Ok(text) => Body::Text(text.to_string()),
+            Err(_) => Body::Raw(payload.to_vec()),
+        },
+        ChannelKind::Opaque => Body::Raw(payload.to_vec()),
+    }
+}
+
+/// Build the merged timeline: every stored frame in position order, with a
+/// [`LogEntry::Gap`] inserted wherever an interior position is missing.
+fn timeline(stream: &StoredStream) -> Vec<LogEntry> {
+    let mut out = Vec::with_capacity(stream.len());
+    let mut prev: Option<u64> = None;
+    for frame in stream.frames() {
+        let pos = frame.position.0;
+        if let Some(p) = prev
+            && pos > p + 1
+        {
+            out.push(LogEntry::Gap(GapSpan { start: p + 1, end: pos - 1 }));
+        }
+        out.push(LogEntry::Frame(MergedFrame {
+            position: frame.position,
+            channel: frame.channel.clone(),
+            body: decode_body(&frame.channel, &frame.payload),
+        }));
+        prev = Some(pos);
+    }
+    out
+}
+
+/// **Full merged log view** (spec §9.2): the single timeline across all
+/// channels, in position order, typed records and text lines interleaved,
+/// with gaps surfaced.
+pub fn merged_log(stream: &StoredStream) -> Vec<LogEntry> {
+    timeline(stream)
+}
+
+/// **Replay** (spec §9.2): reconstruct the timeline after the fact, as if
+/// observed live. It is the merged log presented in position order as a
+/// stream — the same complete record, walked front to back the way a live
+/// observer would have seen it arrive.
+pub fn replay(stream: &StoredStream) -> impl Iterator<Item = LogEntry> {
+    timeline(stream).into_iter()
+}
+
+/// **Typed / metric projection** (spec §9.2): decode one typed channel into
+/// a time series of `(position, record)`, in position order. Frames whose
+/// bytes do not parse as `R` are skipped — the projection degrades rather
+/// than failing (spec §9.3); they remain visible as raw bytes in the merged
+/// log.
+pub fn metric_series<R: Record>(stream: &StoredStream) -> Vec<(Position, R)> {
+    let channel = R::channel();
+    stream
+        .frames()
+        .filter(|f| f.channel == channel)
+        .filter_map(|f| R::decode(&f.payload).ok().map(|record| (f.position, record)))
+        .collect()
+}
+
+/// **Tail** (spec §9.2): the last `n` frames in position order (fewer if
+/// the stream is shorter).
+pub fn tail(stream: &StoredStream, n: usize) -> Vec<Frame> {
+    let all = stream.to_vec();
+    let start = all.len().saturating_sub(n);
+    all[start..].to_vec()
+}
+
+/// **Filter** (spec §9.2): the frames matching a predicate, in position
+/// order.
+pub fn filter<F>(stream: &StoredStream, predicate: F) -> Vec<Frame>
+where
+    F: Fn(&Frame) -> bool,
+{
+    stream.frames().filter(|f| predicate(f)).cloned().collect()
+}
+
+/// **Grep** (spec §9.2): the frames whose payload, read as text, contains
+/// `needle`. Works uniformly across typed channels (their JSON bytes) and
+/// text channels (their lines); binary payloads simply do not match.
+pub fn grep(stream: &StoredStream, needle: &str) -> Vec<Frame> {
+    filter(stream, |f| String::from_utf8_lossy(&f.payload).contains(needle))
+}
+
+// ── Human-readable rendering ───────────────────────────────────────────
+
+impl fmt::Display for Body {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Body::Record(value) => write!(f, "{value}"),
+            Body::Text(text) => f.write_str(text),
+            Body::Raw(bytes) => write!(f, "<{} opaque bytes>", bytes.len()),
+        }
+    }
+}
+
+impl fmt::Display for LogEntry {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            LogEntry::Frame(frame) => {
+                write!(f, "#{:<4} [{}] {}", frame.position, frame.channel, frame.body)
+            }
+            LogEntry::Gap(span) => {
+                write!(f, "#{:<4} ── gap: {} position(s) missing ──", span.start, span.count())
+            }
+        }
+    }
+}
diff --git a/crates/distribution/src/datastream/wire.rs b/crates/distribution/src/datastream/wire.rs
new file mode 100644
index 0000000..7574ba6
--- /dev/null
+++ b/crates/distribution/src/datastream/wire.rs
@@ -0,0 +1,121 @@
+//! The transport envelope: how a delivered frame is encoded as bytes for
+//! a real carrier (spec §7, testing spec §9).
+//!
+//! This is the **only** place the transport touches a frame as bytes. The
+//! envelope is self-describing and length-prefixed so it can be framed on
+//! any byte transport (a datagram, a length-delimited stream). It MUST
+//! round-trip exactly — the conformance check (testing spec §9) leans on
+//! "payloads byte-identical, positions intact" — and it MUST fail
+//! gracefully on a truncated or malformed buffer rather than panic, since
+//! a best-effort carrier can hand us anything.
+//!
+//! Layout (all integers little-endian):
+//!
+//! ```text
+//!   node_len: u32 | node: utf8[node_len]
+//!   life:     u64
+//!   position: u64
+//!   chan_len: u32 | channel: utf8[chan_len]
+//!   pay_len:  u32 | payload: bytes[pay_len]
+//! ```
+
+use super::frame::{ChannelId, Frame, Lifetime, NodeId, Position, StreamId};
+
+/// Why a buffer could not be decoded as an envelope. A carrier that
+/// receives one of these drops the datagram (best-effort) rather than
+/// crashing the consumer.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum WireError {
+    /// The buffer ended before a declared field was complete.
+    Truncated,
+    /// A length prefix claimed more bytes than the buffer holds.
+    BadLength,
+    /// A string field was not valid UTF-8.
+    NotUtf8,
+    /// Bytes remained after a complete envelope. One datagram carries
+    /// exactly one frame, so a trailing tail is a malformed buffer.
+    TrailingBytes,
+}
+
+impl std::fmt::Display for WireError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            WireError::Truncated => f.write_str("envelope truncated"),
+            WireError::BadLength => f.write_str("envelope length prefix exceeds buffer"),
+            WireError::NotUtf8 => f.write_str("envelope string field is not valid UTF-8"),
+            WireError::TrailingBytes => f.write_str("bytes remain after a complete envelope"),
+        }
+    }
+}
+
+impl std::error::Error for WireError {}
+
+/// Encode a delivery — a `(StreamId, Frame)` — into a self-describing byte
+/// buffer.
+pub fn encode_delivery(stream: &StreamId, frame: &Frame) -> Vec<u8> {
+    let node = stream.node.as_str().as_bytes();
+    let channel = frame.channel.as_str().as_bytes();
+    let mut out = Vec::with_capacity(4 + node.len() + 8 + 8 + 4 + channel.len() + 4 + frame.payload.len());
+    put_bytes(&mut out, node);
+    out.extend_from_slice(&stream.life.0.to_le_bytes());
+    out.extend_from_slice(&frame.position.0.to_le_bytes());
+    put_bytes(&mut out, channel);
+    put_bytes(&mut out, &frame.payload);
+    out
+}
+
+/// Decode a delivery previously produced by [`encode_delivery`]. Returns a
+/// [`WireError`] on any malformed buffer instead of panicking.
+pub fn decode_delivery(buf: &[u8]) -> Result<(StreamId, Frame), WireError> {
+    let mut cur = Cursor { buf, pos: 0 };
+    let node = cur.take_str()?;
+    let life = Lifetime(cur.take_u64()?);
+    let position = Position(cur.take_u64()?);
+    let channel = cur.take_str()?;
+    let payload = cur.take_bytes()?.to_vec();
+    if cur.pos != buf.len() {
+        return Err(WireError::TrailingBytes);
+    }
+    let stream = StreamId::new(NodeId::new(node), life);
+    let frame = Frame::new(ChannelId::new(channel), position, payload);
+    Ok((stream, frame))
+}
+
+fn put_bytes(out: &mut Vec<u8>, bytes: &[u8]) {
+    out.extend_from_slice(&(bytes.len() as u32).to_le_bytes());
+    out.extend_from_slice(bytes);
+}
+
+struct Cursor<'a> {
+    buf: &'a [u8],
+    pos: usize,
+}
+
+impl<'a> Cursor<'a> {
+    fn take(&mut self, n: usize) -> Result<&'a [u8], WireError> {
+        let end = self.pos.checked_add(n).ok_or(WireError::BadLength)?;
+        let slice = self.buf.get(self.pos..end).ok_or(WireError::Truncated)?;
+        self.pos = end;
+        Ok(slice)
+    }
+
+    fn take_u32(&mut self) -> Result<u32, WireError> {
+        let b = self.take(4)?;
+        Ok(u32::from_le_bytes([b[0], b[1], b[2], b[3]]))
+    }
+
+    fn take_u64(&mut self) -> Result<u64, WireError> {
+        let b = self.take(8)?;
+        Ok(u64::from_le_bytes([b[0], b[1], b[2], b[3], b[4], b[5], b[6], b[7]]))
+    }
+
+    fn take_bytes(&mut self) -> Result<&'a [u8], WireError> {
+        let len = self.take_u32()? as usize;
+        self.take(len)
+    }
+
+    fn take_str(&mut self) -> Result<&'a str, WireError> {
+        let bytes = self.take_bytes()?;
+        std::str::from_utf8(bytes).map_err(|_| WireError::NotUtf8)
+    }
+}
diff --git a/crates/distribution/src/lib.rs b/crates/distribution/src/lib.rs
index b950317..fb8f14a 100644
--- a/crates/distribution/src/lib.rs
+++ b/crates/distribution/src/lib.rs
@@ -10,5 +10,6 @@ pub mod registry;
 pub mod node_metadata;
 pub mod snapshot;
 pub mod diagnostics;
+pub mod datastream;
 #[cfg(feature = "iroh")]
 pub mod iroh_driver;
diff --git a/crates/distribution/tests/datastream_support/mod.rs b/crates/distribution/tests/datastream_support/mod.rs
new file mode 100644
index 0000000..67cb2f7
--- /dev/null
+++ b/crates/distribution/tests/datastream_support/mod.rs
@@ -0,0 +1,243 @@
+//! Shared support for the datastream tests (testing spec §2, §3).
+//!
+//! Two things live here, both deliberately separate from the system under
+//! test so a test never asserts the code against itself:
+//!
+//! * the **payload library** — realistic record shapes and log lines, the
+//!   bytes the pipe will actually carry (testing spec §5: "never
+//!   placeholder text"); and
+//! * the **reference model** — the spec's rules restated as small, total
+//!   functions over sequences (testing spec §3). It is the trusted oracle:
+//!   every test's `expected` is derived from it, never captured from a run.
+//!   It is written naively on purpose (collect, sort, scan) so a reader can
+//!   confirm it against the spec by eye, while the pipe computes the same
+//!   answers the long way.
+//!
+//! This module is `#[path]`-included into more than one test binary, so
+//! some items are unused in some of them.
+#![allow(dead_code)]
+
+use distribution::datastream::catalog::{
+    self, IdentityRecord, LifecycleCost, MembershipTransition, ProcStream, Record, ResourceSample,
+    Role, RuntimeStats, TransportInternals,
+};
+use distribution::datastream::frame::{ChannelId, Frame, Position, StreamId};
+use distribution::datastream::mux::Mux;
+use distribution::datastream::store::GapSpan;
+pub use distribution::datastream::transport::Delivery;
+
+/// An in-process node (testing spec §2 — the faked machine boundary): a
+/// *real* mux plus the producers that feed it. Producers push realistic
+/// bytes in at the producer seam; [`Node::sent`] takes the mux's ordered
+/// output stream — the value on the mux→transport seam. Only the machine
+/// boundary is faked; the mux is the production code.
+pub struct Node {
+    stream: StreamId,
+    mux: Mux,
+}
+
+impl Node {
+    /// Stand up a node for a given stream (node identity + lifetime).
+    pub fn new(stream: StreamId) -> Self {
+        Node { mux: Mux::unbounded(stream.clone()), stream }
+    }
+
+    /// The stream this node produces.
+    pub fn stream_id(&self) -> &StreamId {
+        &self.stream
+    }
+
+    /// A producer emits a typed record on its own channel (spec §6.1).
+    pub fn emit<R: Record>(&self, record: &R) -> Position {
+        self.mux.submit(R::channel(), record.encode())
+    }
+
+    /// A producer emits a line of raw process output (spec §6.2).
+    pub fn emit_text(&self, label: &str, stream: ProcStream, line: &str) -> Position {
+        self.mux.submit(catalog::process_output(label, stream), line.as_bytes().to_vec())
+    }
+
+    /// A producer emits bytes on a channel the consumer may not know
+    /// (spec §6.3) — opaque to everything until a view learns the channel.
+    pub fn emit_opaque(&self, channel: &str, bytes: &[u8]) -> Position {
+        self.mux.submit(ChannelId::new(channel), bytes.to_vec())
+    }
+
+    /// Take the node's ordered output stream (drains the mux).
+    pub fn sent(&self) -> Vec<Frame> {
+        self.mux.drain()
+    }
+}
+
+/// Realistic payloads, drawn on by both the verified vectors (testing spec
+/// §5) and the deployment scenario (testing spec §8). Nothing here is
+/// placeholder text.
+pub mod payloads {
+    use super::*;
+
+    /// A boot/identity record for a node.
+    pub fn identity(node: &str, life: u64) -> IdentityRecord {
+        IdentityRecord {
+            node: node.to_string(),
+            role: Role::Worker,
+            region: "us-east-1".to_string(),
+            life,
+        }
+    }
+
+    /// A plausible resource sample; `tick` nudges the values so a series is
+    /// not constant.
+    pub fn resource(tick: u64) -> ResourceSample {
+        ResourceSample {
+            cpu_pct: 12.5 + (tick % 7) as f32 * 3.0,
+            mem_used_mb: 2048 + (tick % 5) as u32 * 128,
+            mem_total_mb: 16384,
+            gpu_pct: (tick % 4) as f32 * 25.0,
+            disk_used_gb: 40 + (tick % 3) as u32,
+            net_rx_kbps: 900 + (tick % 11) as u32 * 30,
+            net_tx_kbps: 300 + (tick % 13) as u32 * 20,
+        }
+    }
+
+    /// A transport-internals snapshot.
+    pub fn transport(tick: u64) -> TransportInternals {
+        TransportInternals {
+            relay_connected: !tick.is_multiple_of(9),
+            direct_peers: 2 + (tick % 3) as u32,
+            relay_peers: 1,
+            rtt_ms_p50: 18 + (tick % 5) as u32 * 4,
+        }
+    }
+
+    /// A membership transition between two peers' states.
+    pub fn membership(peer: &str, from: &str, to: &str) -> MembershipTransition {
+        MembershipTransition {
+            peer: peer.to_string(),
+            from: from.to_string(),
+            to: to.to_string(),
+            reason: "probe timeout".to_string(),
+        }
+    }
+
+    /// A runtime-stats record.
+    pub fn runtime(tick: u64) -> RuntimeStats {
+        RuntimeStats {
+            actors_live: 30 + (tick % 6) as u32,
+            mailbox_depth: (tick % 17) as u32,
+            scheduled_tasks: 4 + (tick % 3) as u32,
+        }
+    }
+
+    /// A provider/lifecycle/cost record.
+    pub fn lifecycle(phase: &str, uptime_s: u64) -> LifecycleCost {
+        LifecycleCost { phase: phase.to_string(), cost_usd_per_hr: 1.27, uptime_s }
+    }
+
+    /// A realistic line of process output (without trailing newline).
+    pub fn log_line(label: &str, tick: u64) -> String {
+        format!("[{label}] step {tick} loss=0.{:03} lr=3e-4", 250 - (tick % 200))
+    }
+}
+
+/// The reference model: the spec's rules as plain total functions over
+/// sequences. No transport, no storage, no concurrency, no time.
+pub mod reference {
+    use super::*;
+
+    /// The frames a consumer was delivered for one stream, in arrival
+    /// order — the raw material reconstruction works over.
+    pub fn delivered_frames(stream: &StreamId, deliveries: &[Delivery]) -> Vec<Frame> {
+        deliveries
+            .iter()
+            .filter(|d| &d.stream == stream)
+            .map(|d| d.frame.clone())
+            .collect()
+    }
+
+    /// Reconstruction (spec §8.1, testing spec §3): "keep the frames that
+    /// were delivered, in position order." Duplicates of a position
+    /// collapse to one (the carrier may not fabricate content, spec §9, so
+    /// a repeat carries identical bytes).
+    pub fn reconstruct(delivered: &[Frame]) -> Vec<Frame> {
+        let mut frames: Vec<Frame> = Vec::new();
+        for f in delivered {
+            if !frames.iter().any(|seen| seen.position == f.position) {
+                frames.push(f.clone());
+            }
+        }
+        frames.sort_by_key(|f| f.position);
+        frames
+    }
+
+    /// The surfaced gaps as spans: the **interior** runs of positions missing
+    /// between the first and last delivered position (spec §7.5, §8). A
+    /// consumer can only detect gaps it has bracketing frames for; positions
+    /// lost after the last delivered frame are invisible and manifest as the
+    /// stream ending (spec §7.4 node death = truncation, not a gap).
+    ///
+    /// Walks the sorted delivered positions — O(frames), never the gap size —
+    /// so the oracle agrees with the store on the cheap path even across a
+    /// near-`u64::MAX` gap.
+    pub fn gap_spans(delivered: &[Frame]) -> Vec<GapSpan> {
+        let recon = reconstruct(delivered);
+        let mut spans = Vec::new();
+        let mut prev: Option<u64> = None;
+        for f in &recon {
+            let p = f.position.0;
+            if let Some(q) = prev
+                && p > q + 1
+            {
+                spans.push(GapSpan { start: q + 1, end: p - 1 });
+            }
+            prev = Some(p);
+        }
+        spans
+    }
+
+    /// One structural item on the merged timeline (testing spec §3: "all
+    /// stored frames in position order, channels interleaved"). This is the
+    /// *structure* of the merged log — order and surfaced gaps — decoupled
+    /// from how each payload is rendered for display, which is a separate
+    /// §9.3 concern the tests assert on its own.
+    #[derive(Debug, Clone, PartialEq, Eq)]
+    pub enum TimelineItem {
+        Frame { position: u64, channel: String },
+        Gap { start: u64, end: u64 },
+    }
+
+    /// The merged log oracle (spec §9.2): every delivered frame in position
+    /// order, channels interleaved, with an interior gap surfaced wherever a
+    /// position is missing. Written naively so it is obviously the spec.
+    pub fn merged_log(delivered: &[Frame]) -> Vec<TimelineItem> {
+        let frames = reconstruct(delivered);
+        let mut out = Vec::new();
+        let mut prev: Option<u64> = None;
+        for f in &frames {
+            let pos = f.position.0;
+            if let Some(p) = prev
+                && pos > p + 1
+            {
+                out.push(TimelineItem::Gap { start: p + 1, end: pos - 1 });
+            }
+            out.push(TimelineItem::Frame { position: pos, channel: f.channel.to_string() });
+            prev = Some(pos);
+        }
+        out
+    }
+}
+
+/// Convenience: build a frame on a typed channel from a record.
+pub fn typed_frame<R: Record>(record: &R, position: u64) -> Frame {
+    Frame::new(R::channel(), Position(position), record.encode())
+}
+
+/// Convenience: build a frame on a raw-text process-output channel.
+pub fn text_frame(label: &str, stream: ProcStream, line: &str, position: u64) -> Frame {
+    Frame::new(catalog::process_output(label, stream), Position(position), line.as_bytes().to_vec())
+}
+
+/// Convenience: a frame on a channel id the consumer does not know — an
+/// opaque channel (spec §6.3).
+pub fn opaque_frame(id: &str, payload: &[u8], position: u64) -> Frame {
+    Frame::new(ChannelId::new(id), Position(position), payload.to_vec())
+}
diff --git a/crates/distribution/tests/t_datastream.rs b/crates/distribution/tests/t_datastream.rs
new file mode 100644
index 0000000..6956a5e
--- /dev/null
+++ b/crates/distribution/tests/t_datastream.rs
@@ -0,0 +1,990 @@
+//! Datastream verification harness (see `DATASTREAM_TESTING_SPEC.md`).
+//!
+//! The tests climb the ladder of testing spec §4: Kind I verified vectors
+//! (one rule), Kind II seam tests (one boundary), Kind III the full mock
+//! (the assembled pipe), Kind IV a deployment simulation. Every expected
+//! answer is derived from the reference model in [`support::reference`],
+//! never captured from the system under test (testing spec §3). The real-
+//! I/O checks of testing spec §9–§10 live in `t_datastream_realio.rs`.
+
+#[path = "datastream_support/mod.rs"]
+mod support;
+
+use std::sync::Arc;
+
+use distribution::datastream::catalog::{
+    self, ChannelKind, IdentityRecord, LifecycleCost, ProcStream, Record, ResourceSample, Role,
+};
+use distribution::datastream::frame::{ChannelId, Frame, Lifetime, NodeId, Position, StreamId};
+use distribution::datastream::ingest::Consumer;
+use distribution::datastream::mux::Mux;
+use distribution::datastream::store::{GapSpan, StoredStream};
+use distribution::datastream::transport::{Delivery, Reorder, ScriptedTransport, StreamScript};
+use distribution::datastream::views::{self, Body, LogEntry};
+use distribution::datastream::wire::{decode_delivery, encode_delivery, WireError};
+
+use support::reference::TimelineItem;
+use support::{payloads, reference, Node};
+
+/// The frames of `sent` that survive dropping `dropped`, in send order —
+/// the scenario's delivered set, derived without running the pipe.
+fn surviving(sent: &[Frame], dropped: &[u64]) -> Vec<Frame> {
+    let drop: std::collections::BTreeSet<u64> = dropped.iter().copied().collect();
+    sent.iter().filter(|f| !drop.contains(&f.position.0)).cloned().collect()
+}
+
+/// A node that has emitted a realistic spread of channels: identity, two
+/// resource samples, a transport snapshot, a membership transition, runtime
+/// stats, two lines of process output, and a lifecycle record.
+fn busy_node(stream: &StreamId) -> Vec<Frame> {
+    let node = Node::new(stream.clone());
+    node.emit(&payloads::identity(stream.node.as_str(), stream.life.0)); // 0
+    node.emit(&payloads::resource(0)); // 1
+    node.emit_text("trainer", ProcStream::Stdout, &payloads::log_line("trainer", 0)); // 2
+    node.emit(&payloads::transport(1)); // 3
+    node.emit(&payloads::membership("node-beta", "alive", "suspect")); // 4
+    node.emit(&payloads::resource(1)); // 5
+    node.emit(&payloads::runtime(2)); // 6
+    node.emit_text("trainer", ProcStream::Stderr, "WARN cuda oom, retrying"); // 7
+    node.emit(&payloads::lifecycle("running", 1800)); // 8
+    node.emit(&payloads::resource(2)); // 9
+    node.sent()
+}
+
+/// Carry a node's sent frames through the scripted transport and ingest the
+/// result, returning the consumer (whose store the views read).
+fn consume(stream: &StreamId, sent: &[Frame], script: StreamScript) -> Consumer {
+    let delivered = ScriptedTransport::carry(stream, sent, &script);
+    let mut consumer = Consumer::new();
+    consumer.ingest(delivered);
+    consumer
+}
+
+/// Project a view's merged log down to its structural skeleton — order and
+/// surfaced gaps — so it can be compared to the reference oracle.
+fn structure(entries: &[LogEntry]) -> Vec<TimelineItem> {
+    entries
+        .iter()
+        .map(|e| match e {
+            LogEntry::Frame(mf) => {
+                TimelineItem::Frame { position: mf.position.0, channel: mf.channel.to_string() }
+            }
+            LogEntry::Gap(span) => TimelineItem::Gap { start: span.start, end: span.end },
+        })
+        .collect()
+}
+
+fn test_stream() -> StreamId {
+    StreamId::new(NodeId::new("node-alpha"), Lifetime(1))
+}
+
+// ── Kind I — verified vectors (testing spec §5) ────────────────────────
+//
+// Each targets a single rule in isolation and asserts a *relationship*
+// (round-trip, byte-equality) rather than a captured literal, so the
+// vector cannot be authored wrong and survives a refactor.
+
+/// The codec round-trips: decoding what was encoded yields the original
+/// record (testing spec §3, §5), for every typed channel in the catalog
+/// (spec §6.1), on realistic payloads.
+#[test]
+fn codec_round_trips_every_typed_channel() {
+    assert_round_trip(&payloads::identity("node-alpha", 1));
+    assert_round_trip(&payloads::resource(3));
+    assert_round_trip(&payloads::transport(4));
+    assert_round_trip(&payloads::membership("node-beta", "alive", "suspect"));
+    assert_round_trip(&payloads::runtime(5));
+    assert_round_trip(&payloads::lifecycle("running", 3600));
+}
+
+fn assert_round_trip<R: Record + PartialEq + std::fmt::Debug>(record: &R) {
+    let decoded = R::decode(&record.encode()).expect("round-trips");
+    assert_eq!(&decoded, record, "decode(encode(r)) must equal r");
+}
+
+/// A typed channel's codec tolerates version skew (spec §6.3): a record
+/// written by a newer producer (extra field) and one written by an older
+/// producer (missing field) both still decode.
+#[test]
+fn typed_codec_tolerates_version_skew() {
+    // Newer producer: an extra, unknown field. The consumer ignores it.
+    let with_extra = br#"{"node":"node-x","role":"worker","region":"eu-west-1",
+        "life":2,"future_field":{"nested":true}}"#;
+    let decoded = IdentityRecord::decode(with_extra).expect("unknown field ignored");
+    assert_eq!(decoded.node, "node-x");
+    assert_eq!(decoded.life, 2);
+
+    // Older producer: a sample that predates several fields. The missing
+    // ones decode to their defaults rather than failing.
+    let sparse = br#"{"cpu_pct":42.0}"#;
+    let decoded = ResourceSample::decode(sparse).expect("missing fields default");
+    assert_eq!(decoded.cpu_pct, 42.0);
+    assert_eq!(decoded.mem_used_mb, 0);
+    assert_eq!(decoded.net_tx_kbps, 0);
+}
+
+/// The transport envelope round-trips exactly (testing spec §9): a decoded
+/// delivery equals the one encoded — payload bytes byte-identical, channel
+/// and position intact — across realistic, unicode, empty, and binary
+/// payloads.
+#[test]
+fn wire_envelope_round_trips() {
+    let stream = StreamId::new(NodeId::new("node-ünïcode-Ω"), Lifetime(7));
+    let cases = vec![
+        support::typed_frame(&payloads::resource(2), 0),
+        support::text_frame("trainer", ProcStream::Stdout, "loss=0.0312 lr=3e-4", 1),
+        // Empty payload — a real edge (a channel may emit a zero-length span).
+        Frame::new(ChannelId::new("proc.trainer.stderr"), Position(2), Vec::new()),
+        // Binary payload on an opaque channel — bytes the consumer cannot read.
+        support::opaque_frame("sensor.raw", &[0u8, 255, 1, 254, 128, 0, 0, 7], 3),
+        // Unicode channel id and payload.
+        Frame::new(ChannelId::new("proc.café.stdout"), Position(4), "café ☕".as_bytes().to_vec()),
+    ];
+
+    for frame in &cases {
+        let bytes = encode_delivery(&stream, frame);
+        let (out_stream, out_frame) = decode_delivery(&bytes).expect("decodes");
+        assert_eq!(out_stream, stream, "stream id intact");
+        assert_eq!(&out_frame, frame, "frame intact (channel, position, payload bytes)");
+        assert_eq!(out_frame.payload, frame.payload, "payload byte-identical");
+    }
+}
+
+/// A best-effort carrier can hand the consumer anything; a truncated or
+/// malformed envelope must fail gracefully (a `WireError`), never panic.
+#[test]
+fn wire_envelope_rejects_malformed_buffers_without_panicking() {
+    let stream = StreamId::new(NodeId::new("node-a"), Lifetime(1));
+    let frame = support::typed_frame(&payloads::resource(1), 9);
+    let good = encode_delivery(&stream, &frame);
+
+    // Every proper prefix is incomplete and must be rejected as an error.
+    for cut in 0..good.len() {
+        match decode_delivery(&good[..cut]) {
+            Err(_) => {}
+            Ok(_) => panic!("truncated buffer of {cut} bytes decoded as if whole"),
+        }
+    }
+    // The full buffer still decodes.
+    assert!(decode_delivery(&good).is_ok());
+
+    // A length prefix that overruns the buffer is a clean error.
+    let mut lying = Vec::new();
+    lying.extend_from_slice(&u32::MAX.to_le_bytes()); // claims 4 GiB of node id
+    assert_eq!(decode_delivery(&lying), Err(WireError::Truncated));
+
+    // One datagram carries exactly one frame: trailing bytes are rejected,
+    // so a malformed concatenation cannot be silently half-read.
+    let mut trailing = good.clone();
+    trailing.push(0xFF);
+    assert_eq!(decode_delivery(&trailing), Err(WireError::TrailingBytes));
+}
+
+/// Opaque retention is byte-exact (spec §6.3, §8.3): a channel the
+/// consumer does not recognize classifies as opaque, and its bytes survive
+/// the envelope unchanged — the relationship "stored bytes equal submitted
+/// bytes" (testing spec §5).
+#[test]
+fn opaque_channel_classifies_and_preserves_bytes() {
+    let id = ChannelId::new("v2.gpu.thermals"); // not in the catalog
+    assert_eq!(catalog::classify(&id), ChannelKind::Opaque);
+
+    let payload: Vec<u8> = (0u8..=255).cycle().take(1000).collect();
+    let frame = Frame::new(id, Position(42), payload.clone());
+    let stream = StreamId::new(NodeId::new("node-z"), Lifetime(3));
+
+    let (_, out) = decode_delivery(&encode_delivery(&stream, &frame)).expect("decodes");
+    assert_eq!(out.payload, payload, "opaque bytes retained whole, byte-identical");
+}
+
+/// The catalog classifies known channels correctly and treats the
+/// process-output family (spec §6.2) as text without enumerating labels.
+#[test]
+fn catalog_classifies_known_and_text_family() {
+    assert_eq!(catalog::classify(&ChannelId::new(catalog::IDENTITY)), ChannelKind::Typed);
+    assert_eq!(catalog::classify(&ChannelId::new(catalog::HOST_RESOURCE)), ChannelKind::Typed);
+    // A process introduced at runtime gets text channels for free.
+    let out = catalog::process_output("inference-server", ProcStream::Stdout);
+    assert_eq!(out.as_str(), "proc.inference-server.stdout");
+    assert_eq!(catalog::classify(&out), ChannelKind::Text);
+}
+
+/// A record carries its own channel (spec §6.1 fixed identity), and that
+/// channel classifies as typed.
+#[test]
+fn records_name_their_own_typed_channel() {
+    assert_eq!(IdentityRecord::channel().as_str(), catalog::IDENTITY);
+    assert_eq!(ResourceSample::channel().as_str(), catalog::HOST_RESOURCE);
+    assert_eq!(catalog::classify(&IdentityRecord::channel()), ChannelKind::Typed);
+    // Role enum encodes in snake_case as the wire expects.
+    let r = IdentityRecord { node: "n".into(), role: Role::Coordinator, region: "r".into(), life: 0 };
+    let json = String::from_utf8(r.encode()).unwrap();
+    assert!(json.contains("\"coordinator\""), "role serializes snake_case: {json}");
+}
+
+// ── The mux: position authority (spec §5) ──────────────────────────────
+
+/// Kind I (testing spec §5) — position assignment is monotonic and
+/// gap-free (spec §5.2): with no overflow, K submissions number `0..K`
+/// exactly, and `submit` returns each position in order.
+#[test]
+fn mux_numbers_monotonic_and_gap_free() {
+    let mux = Mux::unbounded(test_stream());
+    let k = 64u64;
+    for i in 0..k {
+        let pos = mux.submit(catalog::HOST_RESOURCE, payloads::resource(i).encode());
+        assert_eq!(pos, Position(i), "submit returns the next position, in order");
+    }
+    assert_eq!(mux.assigned(), k, "assigned == number of submissions (never skips)");
+    assert_eq!(mux.dropped(), 0, "no overflow, nothing dropped");
+
+    let positions: Vec<u64> = mux.drain().iter().map(|f| f.position.0).collect();
+    assert_eq!(positions, (0..k).collect::<Vec<_>>(), "emitted positions are 0..k, gap-free");
+}
+
+/// Kind II (testing spec §6) — across the mux seam, every submission
+/// appears as exactly one frame, byte-identical, in one interleaved order.
+/// A typed event and a log line share the single timeline (spec §5.1).
+#[test]
+fn mux_seam_preserves_every_submission_byte_identical() {
+    let mux = Mux::unbounded(test_stream());
+
+    // A realistic interleaving of typed records and raw process output —
+    // the same kind of thing on one stream (spec §4.2).
+    let submissions: Vec<(ChannelId, Vec<u8>)> = vec![
+        (catalog::IDENTITY.into(), payloads::identity("node-alpha", 1).encode()),
+        (
+            catalog::process_output("trainer", ProcStream::Stdout),
+            payloads::log_line("trainer", 0).into_bytes(),
+        ),
+        (catalog::HOST_RESOURCE.into(), payloads::resource(1).encode()),
+        (catalog::MEMBERSHIP.into(), payloads::membership("node-beta", "alive", "suspect").encode()),
+        (
+            catalog::process_output("trainer", ProcStream::Stderr),
+            b"WARN cuda oom, retrying".to_vec(),
+        ),
+        (catalog::RUNTIME_STATS.into(), payloads::runtime(2).encode()),
+    ];
+
+    for (channel, payload) in &submissions {
+        mux.submit(channel.clone(), payload.clone());
+    }
+
+    let frames = mux.drain();
+    assert_eq!(frames.len(), submissions.len(), "exactly one frame per submission — none lost");
+    for (i, (frame, (channel, payload))) in frames.iter().zip(&submissions).enumerate() {
+        assert_eq!(frame.position, Position(i as u64), "interleaved in submission order, gap-free");
+        assert_eq!(&frame.channel, channel, "channel tag preserved crossing the seam");
+        assert_eq!(&frame.payload, payload, "payload bytes byte-identical crossing the seam");
+    }
+}
+
+/// Spec §5.3 — on overflow the mux drops the frame, but its position is
+/// already spent, so the loss surfaces as a missing position (a detectable
+/// gap), never a silent renumber. The reference-model gap oracle confirms
+/// the interior gap.
+#[test]
+fn mux_overflow_drops_surface_as_a_gap_not_a_renumber() {
+    let mux = Mux::new(test_stream(), 2); // tiny buffer
+
+    mux.submit(catalog::HOST_RESOURCE, payloads::resource(0).encode()); // pos 0 -> buffered
+    mux.submit(catalog::HOST_RESOURCE, payloads::resource(1).encode()); // pos 1 -> buffered
+    mux.submit(catalog::HOST_RESOURCE, payloads::resource(2).encode()); // pos 2 -> OVERFLOW, dropped
+    let first = mux.drain(); // empties the buffer
+    mux.submit(catalog::HOST_RESOURCE, payloads::resource(3).encode()); // pos 3 -> buffered
+    let second = mux.drain();
+
+    assert_eq!(mux.assigned(), 4, "every submission consumed a position — numbering never skips");
+    assert_eq!(mux.dropped(), 1, "exactly the overflowing frame was dropped");
+
+    let mut emitted: Vec<Frame> = first;
+    emitted.extend(second);
+    let positions: Vec<u64> = emitted.iter().map(|f| f.position.0).collect();
+    assert_eq!(positions, vec![0, 1, 3], "dropped position 2 is simply absent, others not renumbered");
+
+    // The dropped position reads as an interior gap, exactly what the
+    // consumer will later surface (spec §7.5).
+    assert_eq!(
+        reference::gap_spans(&emitted),
+        vec![GapSpan { start: 2, end: 2 }],
+        "the drop is a detectable gap at position 2"
+    );
+}
+
+/// Spec §5.3 — the mux serializes concurrent producers into one order:
+/// every position is assigned exactly once across threads, with no
+/// duplicate and no gap. This is the single-ordering-authority guarantee.
+#[test]
+fn mux_serializes_concurrent_producers_without_collision() {
+    let mux = Arc::new(Mux::unbounded(test_stream()));
+    let threads = 8u64;
+    let per_thread = 500u64;
+
+    let handles: Vec<_> = (0..threads)
+        .map(|t| {
+            let mux = Arc::clone(&mux);
+            std::thread::spawn(move || {
+                let mut mine = Vec::with_capacity(per_thread as usize);
+                for i in 0..per_thread {
+                    // Each thread is a distinct producer writing real bytes.
+                    let pos = mux.submit(catalog::RUNTIME_STATS, payloads::runtime(t * 1000 + i).encode());
+                    mine.push(pos.0);
+                }
+                mine
+            })
+        })
+        .collect();
+
+    let mut assigned: Vec<u64> = handles.into_iter().flat_map(|h| h.join().unwrap()).collect();
+    let total = threads * per_thread;
+    assert_eq!(mux.assigned(), total);
+    assert_eq!(mux.dropped(), 0, "unbounded mux drops nothing");
+
+    assigned.sort_unstable();
+    assert_eq!(assigned, (0..total).collect::<Vec<_>>(), "each position assigned exactly once");
+
+    // The buffered frames carry the same complete set of positions.
+    let mut emitted: Vec<u64> = mux.drain().iter().map(|f| f.position.0).collect();
+    emitted.sort_unstable();
+    assert_eq!(emitted, (0..total).collect::<Vec<_>>(), "no frame lost, no position duplicated");
+}
+
+// ── Transport seam + ingest + store (spec §7, §8) ──────────────────────
+
+/// Build a realistic single-node stream the way a node would: drive the
+/// real mux with a mix of typed records, raw process output, and a channel
+/// the consumer does not know, then take its output.
+fn realistic_stream(stream: &StreamId) -> Vec<Frame> {
+    let mux = Mux::unbounded(stream.clone());
+    mux.submit(catalog::IDENTITY, payloads::identity(stream.node.as_str(), stream.life.0).encode());
+    mux.submit(catalog::HOST_RESOURCE, payloads::resource(0).encode());
+    // A channel this consumer cannot decode — must still be retained whole.
+    mux.submit(ChannelId::new("v2.gpu.thermals"), vec![0xDE, 0xAD, 0xBE, 0xEF]);
+    mux.submit(
+        catalog::process_output("trainer", ProcStream::Stdout),
+        payloads::log_line("trainer", 0).into_bytes(),
+    );
+    mux.submit(catalog::HOST_RESOURCE, payloads::resource(1).encode());
+    mux.submit(catalog::MEMBERSHIP, payloads::membership("node-beta", "alive", "suspect").encode());
+    mux.drain()
+}
+
+/// Kind II (testing spec §6) — across ingest, every delivered frame appears
+/// in the stored stream byte-identical, an undecodable channel is retained
+/// whole, and the gap left by a dropped position is surfaced. Both sides of
+/// the seam are checked against the reference model.
+#[test]
+fn ingest_seam_stores_every_delivered_frame_and_surfaces_gaps() {
+    let stream = test_stream();
+    let sent = realistic_stream(&stream); // positions 0..6
+
+    // The carrier drops one resource sample (interior loss) and scrambles
+    // arrival order within windows — both inside the envelope (spec §9).
+    let script = StreamScript::dropping([4]).with_reorder(Reorder::Windows(3));
+    let delivered = ScriptedTransport::carry(&stream, &sent, &script);
+
+    let mut consumer = Consumer::new();
+    consumer.ingest(delivered.clone());
+    let stored = consumer.store().stream(&stream).expect("stream stored");
+
+    // Derive the trusted answer from the reference model, never from the run.
+    let delivered_frames = reference::delivered_frames(&stream, &delivered);
+    assert_eq!(
+        stored.to_vec(),
+        reference::reconstruct(&delivered_frames),
+        "stored stream equals the reference reconstruction (every delivered frame, in position order)"
+    );
+    assert_eq!(
+        stored.gap_spans(),
+        reference::gap_spans(&delivered_frames),
+        "the dropped position is surfaced as a gap"
+    );
+    assert_eq!(
+        stored.gap_spans(),
+        vec![GapSpan { start: 4, end: 4 }],
+        "specifically position 4 is missing"
+    );
+
+    // The undecodable channel landed whole, byte-identical (spec §8.3).
+    let opaque = stored.at(Position(2)).expect("opaque frame retained");
+    assert_eq!(opaque.channel, ChannelId::new("v2.gpu.thermals"));
+    assert_eq!(opaque.payload, vec![0xDE, 0xAD, 0xBE, 0xEF], "opaque bytes retained whole");
+    assert_eq!(catalog::classify(&opaque.channel), ChannelKind::Opaque);
+}
+
+/// Spec §7.5 — the consumer reconstructs by position, not by arrival: even
+/// when the carrier delivers a stream fully reversed, the stored stream is
+/// in position order and identical to the in-order case.
+#[test]
+fn ingest_reconstructs_by_position_not_arrival_order() {
+    let stream = test_stream();
+    let sent = realistic_stream(&stream);
+
+    let reversed = ScriptedTransport::carry(
+        &stream,
+        &sent,
+        &StreamScript::perfect().with_reorder(Reorder::Reversed),
+    );
+    // The carrier really did reverse arrival: first delivered is last sent.
+    assert_eq!(reversed.first().unwrap().frame.position, sent.last().unwrap().position);
+
+    let mut consumer = Consumer::new();
+    consumer.ingest(reversed);
+    let stored = consumer.store().stream(&stream).unwrap();
+
+    assert_eq!(stored.to_vec(), sent, "reconstruction restores the sent order from reversed arrival");
+}
+
+/// Spec §9 (no fabrication) — a position delivered twice collapses to one
+/// stored frame; ingest is idempotent and append-only.
+#[test]
+fn ingest_is_idempotent_on_duplicate_positions() {
+    let stream = test_stream();
+    let frame = support::typed_frame(&payloads::resource(0), 0);
+
+    let mut consumer = Consumer::new();
+    consumer.accept(Delivery::new(stream.clone(), frame.clone()));
+    let was_new = consumer.accept(Delivery::new(stream.clone(), frame.clone()));
+
+    assert!(!was_new, "a repeated position is not recorded a second time");
+    assert_eq!(consumer.store().stream(&stream).unwrap().len(), 1, "exactly one frame stored");
+}
+
+/// Spec §8.4 — a node identity reused across lifetimes does not merge: each
+/// life is its own stored stream, even though both begin at position 0 with
+/// an identity frame.
+#[test]
+fn reincarnated_node_does_not_merge_with_prior_life() {
+    let node = "node-worker-7";
+    let life1 = StreamId::new(NodeId::new(node), Lifetime(1));
+    let life2 = StreamId::new(NodeId::new(node), Lifetime(2)); // same node, new life
+    let other = StreamId::new(NodeId::new("node-worker-8"), Lifetime(1));
+
+    let s1 = realistic_stream(&life1);
+    let s2 = realistic_stream(&life2);
+    let s3 = realistic_stream(&other);
+
+    // Interleaved on one wire; ingest must route by stream id alone.
+    let delivered = ScriptedTransport::carry_all(&[
+        (life1.clone(), s1.clone(), StreamScript::perfect()),
+        (life2.clone(), s2.clone(), StreamScript::perfect()),
+        (other.clone(), s3.clone(), StreamScript::perfect()),
+    ]);
+
+    let mut consumer = Consumer::new();
+    consumer.ingest(delivered);
+    let store = consumer.store();
+
+    assert_eq!(store.len(), 3, "three distinct streams, none merged");
+    assert_eq!(store.stream(&life1).unwrap().to_vec(), s1);
+    assert_eq!(store.stream(&life2).unwrap().to_vec(), s2);
+    assert_eq!(store.stream(&other).unwrap().to_vec(), s3);
+
+    // Both lives have a position-0 identity frame; they did not collide.
+    let id1 = store.stream(&life1).unwrap().at(Position(0)).unwrap();
+    let id2 = store.stream(&life2).unwrap().at(Position(0)).unwrap();
+    assert_ne!(id1.payload, id2.payload, "each life's identity frame is its own");
+    assert_eq!(
+        IdentityRecord::decode(&id1.payload).unwrap().life,
+        1,
+        "life-1 identity attributes to lifetime 1"
+    );
+    assert_eq!(IdentityRecord::decode(&id2.payload).unwrap().life, 2);
+}
+
+// ── Views: read-time projections (spec §9) ─────────────────────────────
+
+/// Kind II (testing spec §6) — the merged log view (spec §9.2) is every
+/// stored frame in position order, channels interleaved, with the dropped
+/// position surfaced as a gap. Its structure equals the reference oracle.
+#[test]
+fn merged_log_matches_oracle_with_surfaced_gap() {
+    let stream = test_stream();
+    let sent = realistic_stream(&stream); // positions 0..6, mixed channels
+    let script = StreamScript::dropping([3]).with_reorder(Reorder::Reversed);
+    let delivered = ScriptedTransport::carry(&stream, &sent, &script);
+
+    let mut consumer = Consumer::new();
+    consumer.ingest(delivered.clone());
+    let stored = consumer.store().stream(&stream).unwrap();
+
+    let log = views::merged_log(stored);
+    let expected = reference::merged_log(&reference::delivered_frames(&stream, &delivered));
+    assert_eq!(structure(&log), expected, "merged log = timeline in position order with gap surfaced");
+
+    // The gap sits between the bracketing frames, not at the end.
+    assert!(
+        log.iter().any(|e| matches!(e, LogEntry::Gap(g) if g.start == 3 && g.end == 3)),
+        "position 3 is surfaced as an interior gap"
+    );
+}
+
+/// Kind I (testing spec §5) — a view decodes each channel via its codec and
+/// degrades to raw bytes over anything it cannot decode (spec §9.3): a typed
+/// channel decodes to a record, a text channel to lines, an unknown channel
+/// to bytes, and a typed channel carrying garbage degrades rather than
+/// failing.
+#[test]
+fn view_decodes_each_channel_and_degrades_gracefully() {
+    // Typed channel → structured record.
+    let resource = payloads::resource(2);
+    match views::decode_body(&ResourceSample::channel(), &resource.encode()) {
+        Body::Record(value) => {
+            assert!(value.get("cpu_pct").is_some(), "typed channel decodes to its record fields");
+        }
+        other => panic!("typed channel should decode to a record, got {other:?}"),
+    }
+
+    // Raw-text channel → its line.
+    let line = payloads::log_line("trainer", 7);
+    let text_channel = catalog::process_output("trainer", ProcStream::Stdout);
+    assert_eq!(views::decode_body(&text_channel, line.as_bytes()), Body::Text(line.clone()));
+
+    // Unknown channel → raw bytes (graceful, spec §6.3/§9.3).
+    let opaque = ChannelId::new("v2.gpu.thermals");
+    assert_eq!(views::decode_body(&opaque, &[0xDE, 0xAD]), Body::Raw(vec![0xDE, 0xAD]));
+
+    // Typed channel, garbage bytes → degrades to raw, never panics or drops.
+    let garbage = b"not-json{oops".to_vec();
+    assert_eq!(
+        views::decode_body(&ResourceSample::channel(), &garbage),
+        Body::Raw(garbage.clone()),
+        "a typed channel that fails to parse degrades to bytes (spec §9.3)"
+    );
+}
+
+/// Kind I (testing spec §5) — the metric projection (spec §9.2) decodes one
+/// typed channel into a time series, in position order, leaving the other
+/// channels untouched. Expected is the records that were emitted.
+#[test]
+fn metric_projection_decodes_one_typed_channel_into_a_series() {
+    let stream = test_stream();
+    let mux = Mux::unbounded(stream.clone());
+    mux.submit(catalog::IDENTITY, payloads::identity("node-alpha", 1).encode());
+
+    let mut expected: Vec<(Position, ResourceSample)> = Vec::new();
+    for i in 0..5 {
+        let sample = payloads::resource(i);
+        let pos = mux.submit(catalog::HOST_RESOURCE, sample.encode());
+        expected.push((pos, sample));
+        // Interleave an unrelated channel — the projection must ignore it.
+        mux.submit(catalog::MEMBERSHIP, payloads::membership("p", "alive", "dead").encode());
+    }
+    let sent = mux.drain();
+
+    let consumer = consume(&stream, &sent, StreamScript::perfect());
+    let series = views::metric_series::<ResourceSample>(consumer.store().stream(&stream).unwrap());
+
+    assert_eq!(series, expected, "the resource series is exactly the samples emitted, in order");
+}
+
+/// Kind I (testing spec §5) — tail, grep, and filter are windowed /
+/// predicate views over the stream (spec §9.2).
+#[test]
+fn tail_grep_and_filter_restrict_the_stream() {
+    let stream = test_stream();
+    let sent = realistic_stream(&stream); // id, resource, opaque, proc, resource, membership
+    let consumer = consume(&stream, &sent, StreamScript::perfect());
+    let stored = consumer.store().stream(&stream).unwrap();
+
+    // Tail: the last two frames by position.
+    let last_two = views::tail(stored, 2);
+    assert_eq!(last_two, stored.to_vec()[4..].to_vec(), "tail(2) is the final two frames in order");
+
+    // Grep: only the membership transition mentions "suspect".
+    let hits = views::grep(stored, "suspect");
+    assert_eq!(hits.len(), 1, "exactly one frame matches the needle");
+    assert_eq!(hits[0].channel, ChannelId::new(catalog::MEMBERSHIP));
+
+    // Filter: restrict to a single channel.
+    let resources = views::filter(stored, |f| f.channel == ResourceSample::channel());
+    assert_eq!(resources.len(), 2, "two resource samples in the stream");
+    assert!(resources.iter().all(|f| f.channel == ResourceSample::channel()));
+}
+
+/// Boundary — views over an empty stream are empty, and a single-frame
+/// stream has no gaps. Views must not panic at the edges.
+#[test]
+fn views_handle_empty_and_singleton_streams() {
+    let empty = StoredStream::new();
+    assert!(views::merged_log(&empty).is_empty());
+    assert!(views::tail(&empty, 5).is_empty());
+    assert!(views::metric_series::<ResourceSample>(&empty).is_empty());
+    assert_eq!(views::replay(&empty).count(), 0);
+
+    let mut one = StoredStream::new();
+    one.record(support::typed_frame(&payloads::resource(0), 0));
+    let log = views::merged_log(&one);
+    assert_eq!(log.len(), 1, "one frame, one entry");
+    assert!(matches!(log[0], LogEntry::Frame(_)), "no spurious gap around a lone frame");
+}
+
+/// Resource safety (spec §7.4/§7.5) — surfacing a gap costs O(stored frames),
+/// never O(gap size). A long consumer outage, or a single wild position from
+/// a corrupt best-effort datagram, can leave the store bracketing an enormous
+/// interior gap. Surfacing it must be one span computed from the bracketing
+/// frames, not an enumeration of the missing range (which would hang / OOM
+/// the single consumer). The reference oracle agrees on the same cheap path.
+#[test]
+fn gap_surfacing_is_bounded_by_frame_count_not_gap_size() {
+    // The largest interior gap a u64 position space admits.
+    let mut extreme = StoredStream::new();
+    extreme.record(support::typed_frame(&payloads::resource(0), 0));
+    let high = Frame::new(ResourceSample::channel(), Position(u64::MAX), payloads::resource(1).encode());
+    extreme.record(high.clone());
+
+    // Were this O(gap size), the next line would never return.
+    assert_eq!(
+        extreme.gap_spans(),
+        vec![GapSpan { start: 1, end: u64::MAX - 1 }],
+        "one span covers the whole interior gap"
+    );
+    assert_eq!(
+        reference::gap_spans(&extreme.to_vec()),
+        extreme.gap_spans(),
+        "oracle agrees on the cheap path"
+    );
+
+    // The merged log over the same store is also O(frames): two frames with
+    // a single gap span between them, not a billion entries.
+    let log = views::merged_log(&extreme);
+    assert_eq!(log.len(), 3, "two frames and one gap span");
+    assert!(matches!(log[1], LogEntry::Gap(_)), "the gap sits between the bracketing frames");
+
+    // A realistic long outage (millions of dropped positions) is just as cheap.
+    let mut outage = StoredStream::new();
+    outage.record(support::typed_frame(&payloads::resource(0), 0));
+    for p in 5_000_000u64..5_000_003 {
+        outage.record(support::typed_frame(&payloads::resource(p), p));
+    }
+    assert_eq!(
+        outage.gap_spans(),
+        vec![GapSpan { start: 1, end: 4_999_999 }],
+        "the outage is one surfaced span, the stream resumes after it"
+    );
+}
+
+// ── Kind III — the full mock (testing spec §7) ─────────────────────────
+//
+// Each test assembles the ENTIRE pipe — producers → real mux → scripted
+// transport seam → real ingest → store → merged-log view — and drives it
+// with one verified vector, checking the view (the consumer-facing end)
+// against the reference oracle. The oracle's `expected` is derived from the
+// scenario (emitted frames + the script's drops), never from the run, and
+// is blind to delivery order — which is precisely the property the pipe
+// must satisfy.
+
+/// Adversarial vector — reordering as deep as the envelope allows. Delivered
+/// fully reversed, the assembled pipe still reconstructs the exact timeline:
+/// reconstruction does not assume arrival order (spec §7.5).
+#[test]
+fn full_mock_survives_deepest_reorder() {
+    let id = StreamId::new(NodeId::new("node-mock-1"), Lifetime(1));
+    let sent = busy_node(&id);
+
+    let script = StreamScript::perfect().with_reorder(Reorder::Reversed);
+    let delivered = ScriptedTransport::carry(&id, &sent, &script);
+
+    let mut consumer = Consumer::new();
+    consumer.ingest(delivered);
+    let stored = consumer.store().stream(&id).unwrap();
+    let log = views::merged_log(stored);
+
+    assert_eq!(
+        structure(&log),
+        reference::merged_log(&surviving(&sent, &[])),
+        "merged log equals the oracle despite the deepest reorder"
+    );
+    assert!(stored.gap_spans().is_empty(), "nothing dropped — no gaps");
+    assert_eq!(stored.to_vec(), sent, "full timeline restored from fully reversed arrival");
+}
+
+/// Adversarial vector — total loss of a span. A whole contiguous run of
+/// positions never arrives (and survivors are reordered too); the view
+/// surfaces one gap and the stream resumes after it, without replaying lost
+/// history (spec §7.4, §7.5).
+#[test]
+fn full_mock_surfaces_total_span_loss_and_resumes() {
+    let id = StreamId::new(NodeId::new("node-mock-2"), Lifetime(1));
+    let sent = busy_node(&id); // positions 0..10
+    let lost = [4u64, 5, 6, 7]; // an entire span vanishes
+
+    let script = StreamScript::dropping(lost).with_reorder(Reorder::Windows(3));
+    let delivered = ScriptedTransport::carry(&id, &sent, &script);
+
+    let mut consumer = Consumer::new();
+    consumer.ingest(delivered);
+    let stored = consumer.store().stream(&id).unwrap();
+
+    assert_eq!(
+        structure(&views::merged_log(stored)),
+        reference::merged_log(&surviving(&sent, &lost)),
+        "view equals the oracle with the span surfaced as a gap"
+    );
+    assert_eq!(
+        stored.gap_spans(),
+        vec![GapSpan { start: 4, end: 7 }],
+        "the lost span is one surfaced gap, not silent concatenation"
+    );
+
+    // The stream resumes with the original post-gap frames — nothing from
+    // the lost span reappears, and history is not replayed.
+    assert!(stored.frames().all(|f| !lost.contains(&f.position.0)), "lost span absent");
+    let after: Vec<Frame> = stored.frames().filter(|f| f.position.0 >= 8).cloned().collect();
+    let original_after: Vec<Frame> = sent.iter().filter(|f| f.position.0 >= 8).cloned().collect();
+    assert_eq!(after, original_after, "resumes at position 8 with the originals, in order");
+}
+
+/// Adversarial vector — a channel the consumer cannot decode. Its bytes are
+/// a perfectly valid record, but on a channel the catalog does not know:
+/// the pipe stores it whole, a view degrades it to raw bytes now, and it
+/// decodes later once the channel is learned (spec §6.3, §8.3).
+#[test]
+fn full_mock_stores_undecodable_channel_and_decodes_it_later() {
+    let id = StreamId::new(NodeId::new("node-mock-3"), Lifetime(1));
+    let node = Node::new(id.clone());
+    node.emit(&payloads::identity("node-mock-3", 1)); // 0
+    // A future host-metric channel this consumer has never heard of, whose
+    // payload happens to be a valid resource sample.
+    let future = payloads::resource(3);
+    let future_channel = "v2.future.host_metric";
+    node.emit_opaque(future_channel, &future.encode()); // 1
+    node.emit(&payloads::runtime(1)); // 2
+    let sent = node.sent();
+
+    let delivered = ScriptedTransport::carry(&id, &sent, &StreamScript::perfect());
+    let mut consumer = Consumer::new();
+    consumer.ingest(delivered);
+    let stored = consumer.store().stream(&id).unwrap();
+
+    // Now: the view cannot decode it, so it degrades to raw bytes (§9.3),
+    // but the frame is present and whole.
+    let log = views::merged_log(stored);
+    let entry = log
+        .iter()
+        .find_map(|e| match e {
+            LogEntry::Frame(mf) if mf.position == Position(1) => Some(mf),
+            _ => None,
+        })
+        .expect("the unknown-channel frame is on the timeline");
+    assert!(matches!(entry.body, Body::Raw(_)), "unknown channel degrades to raw bytes now");
+
+    let raw = stored.at(Position(1)).unwrap();
+    assert_eq!(raw.channel, ChannelId::new(future_channel), "retained on its own channel");
+
+    // Later: once the channel is learned, the stored bytes decode to the
+    // original record — nothing was lost at ingest.
+    let decoded = ResourceSample::decode(&raw.payload).expect("decodes once the channel is known");
+    assert_eq!(decoded, future, "the opaque bytes were the record all along");
+}
+
+/// Adversarial vector — a node identity reused across lifetimes. Two lives
+/// of one node flow into the one consumer (one delivered reversed); at the
+/// view end they are two separate timelines that never merge (spec §8.4).
+#[test]
+fn full_mock_reused_identity_does_not_merge_at_the_view() {
+    let node = "node-recycled";
+    let life1 = StreamId::new(NodeId::new(node), Lifetime(1));
+    let life2 = StreamId::new(NodeId::new(node), Lifetime(2));
+
+    let s1 = busy_node(&life1);
+    let s2 = busy_node(&life2);
+
+    let delivered = ScriptedTransport::carry_all(&[
+        (life1.clone(), s1.clone(), StreamScript::perfect()),
+        (life2.clone(), s2.clone(), StreamScript::perfect().with_reorder(Reorder::Reversed)),
+    ]);
+
+    let mut consumer = Consumer::new();
+    consumer.ingest(delivered);
+    let store = consumer.store();
+    assert_eq!(store.len(), 2, "two lives, two streams — never merged");
+
+    let log1 = views::merged_log(store.stream(&life1).unwrap());
+    let log2 = views::merged_log(store.stream(&life2).unwrap());
+    assert_eq!(structure(&log1), reference::merged_log(&surviving(&s1, &[])));
+    assert_eq!(structure(&log2), reference::merged_log(&surviving(&s2, &[])));
+
+    // Each life's position-0 identity frame is its own, correctly attributed.
+    let id1 = IdentityRecord::decode(&store.stream(&life1).unwrap().at(Position(0)).unwrap().payload)
+        .unwrap();
+    let id2 = IdentityRecord::decode(&store.stream(&life2).unwrap().at(Position(0)).unwrap().payload)
+        .unwrap();
+    assert_eq!((id1.life, id2.life), (1, 2), "identities attribute to their own lifetimes");
+}
+
+/// Envelope coverage (testing spec §9) — an explicit arrival permutation,
+/// distinct from full reversal: the carrier delivers evens then odds. The
+/// carrier applies exactly that permutation (no fabrication or loss), and
+/// the pipe reconstructs the send order regardless.
+#[test]
+fn full_mock_reconstructs_under_explicit_permutation() {
+    let id = StreamId::new(NodeId::new("node-perm"), Lifetime(1));
+    let sent = busy_node(&id);
+    let n = sent.len();
+
+    // Deliver all even indices first, then all odd ones.
+    let perm: Vec<usize> =
+        (0..n).filter(|i| i.is_multiple_of(2)).chain((0..n).filter(|i| !i.is_multiple_of(2))).collect();
+    let script = StreamScript::perfect().with_reorder(Reorder::Permutation(perm.clone()));
+    let delivered = ScriptedTransport::carry(&id, &sent, &script);
+
+    // The carrier delivered exactly the scripted permutation of positions.
+    let arrival: Vec<u64> = delivered.iter().map(|d| d.frame.position.0).collect();
+    let expected_arrival: Vec<u64> = perm.iter().map(|&i| sent[i].position.0).collect();
+    assert_eq!(arrival, expected_arrival, "delivered in the scripted permutation, nothing added or lost");
+
+    let mut consumer = Consumer::new();
+    consumer.ingest(delivered);
+    let stored = consumer.store().stream(&id).unwrap();
+    assert_eq!(stored.to_vec(), sent, "reconstruction restores send order from the permutation");
+    assert_eq!(
+        structure(&views::merged_log(stored)),
+        reference::merged_log(&surviving(&sent, &[])),
+        "merged log equals the oracle"
+    );
+}
+
+// ── Kind IV — the deployment simulation (testing spec §8) ──────────────
+
+/// Record the virtual tick at which a position was emitted (positions are
+/// contiguous from 0, so the tick vector is indexed by position).
+fn at_tick(ticks: &mut Vec<u64>, tick: u64, pos: Position) {
+    assert_eq!(pos.0 as usize, ticks.len(), "positions emitted contiguously");
+    ticks.push(tick);
+}
+
+/// The positions a node emitted during an outage window — the frames lost
+/// while the consumer was absent (spec §7.4).
+fn emitted_during(tick_of: &[u64], outage_ticks: &[u64]) -> Vec<u64> {
+    tick_of
+        .iter()
+        .enumerate()
+        .filter(|(_, t)| outage_ticks.contains(t))
+        .map(|(pos, _)| pos as u64)
+        .collect()
+}
+
+/// A scenario shaped like a real run (testing spec §8): three nodes boot and
+/// emit on real channels at real cadence over a virtual clock; the carrier
+/// drops one frame; the consumer is absent for a span; one node dies; one
+/// finalizes. Every fault is in the §9 envelope. The end-to-end answer is
+/// the full merged-log view over the consumer's store, **derived from the
+/// scenario by the reference model** — so the expected log already carries
+/// the right gaps, the dead node already ends at its last delivered frame,
+/// and the outage span is already absent. The simulation passes only if the
+/// assembled pipe reproduces every node's log exactly.
+#[test]
+fn kind_iv_deployment_simulation() {
+    const OUTAGE: [u64; 3] = [4, 5, 6]; // ticks the consumer is absent
+
+    // ── Node A: lives the whole run and finalizes at t8 ────────────────
+    let id_a = StreamId::new(NodeId::new("node-a"), Lifetime(1));
+    let a = Node::new(id_a.clone());
+    let mut a_ticks = Vec::new();
+    at_tick(&mut a_ticks, 0, a.emit(&payloads::identity("node-a", 1)));
+    for t in 1..=5 {
+        at_tick(&mut a_ticks, t, a.emit(&payloads::resource(t)));
+    }
+    at_tick(&mut a_ticks, 7, a.emit(&payloads::resource(7))); // resumes after the outage
+    at_tick(&mut a_ticks, 8, a.emit(&payloads::lifecycle("finalized", 7200))); // finalize
+    let sent_a = a.sent();
+
+    // ── Node B: lives, and also emits membership transitions ───────────
+    let id_b = StreamId::new(NodeId::new("node-b"), Lifetime(1));
+    let b = Node::new(id_b.clone());
+    let mut b_ticks = Vec::new();
+    at_tick(&mut b_ticks, 0, b.emit(&payloads::identity("node-b", 1)));
+    at_tick(&mut b_ticks, 1, b.emit(&payloads::resource(1)));
+    at_tick(&mut b_ticks, 2, b.emit(&payloads::resource(2)));
+    at_tick(&mut b_ticks, 2, b.emit(&payloads::membership("node-c", "alive", "suspect")));
+    at_tick(&mut b_ticks, 3, b.emit(&payloads::resource(3)));
+    at_tick(&mut b_ticks, 4, b.emit(&payloads::resource(4)));
+    at_tick(&mut b_ticks, 4, b.emit(&payloads::membership("node-c", "suspect", "dead")));
+    at_tick(&mut b_ticks, 5, b.emit(&payloads::resource(5)));
+    at_tick(&mut b_ticks, 7, b.emit(&payloads::resource(7)));
+    at_tick(&mut b_ticks, 8, b.emit(&payloads::runtime(8)));
+    let sent_b = b.sent();
+
+    // ── Node C: dies at t6 (emits nothing after t5) ────────────────────
+    let id_c = StreamId::new(NodeId::new("node-c"), Lifetime(1));
+    let c = Node::new(id_c.clone());
+    let mut c_ticks = Vec::new();
+    at_tick(&mut c_ticks, 0, c.emit(&payloads::identity("node-c", 1)));
+    for t in 1..=5 {
+        at_tick(&mut c_ticks, t, c.emit(&payloads::resource(t)));
+    }
+    // t6: dies. Nothing more is emitted.
+    let sent_c = c.sent();
+
+    // ── Faults, all inside the §9 envelope ─────────────────────────────
+    // The carrier drops A's t3 resource frame (a known single drop).
+    let mut drop_a = emitted_during(&a_ticks, &OUTAGE);
+    drop_a.push(3);
+    let drop_b = emitted_during(&b_ticks, &OUTAGE);
+    let drop_c = emitted_during(&c_ticks, &OUTAGE);
+
+    // Each node's surviving frames may also arrive reordered, at varying
+    // depth — reconstruction must not care.
+    let delivered = ScriptedTransport::carry_all(&[
+        (id_a.clone(), sent_a.clone(), StreamScript::dropping(drop_a.clone())),
+        (
+            id_b.clone(),
+            sent_b.clone(),
+            StreamScript::dropping(drop_b.clone()).with_reorder(Reorder::Windows(3)),
+        ),
+        (
+            id_c.clone(),
+            sent_c.clone(),
+            StreamScript::dropping(drop_c.clone()).with_reorder(Reorder::Reversed),
+        ),
+    ]);
+
+    let mut consumer = Consumer::new();
+    consumer.ingest(delivered);
+    let store = consumer.store();
+
+    // ── The end-to-end answer: each node's full merged-log view equals the
+    //    reference model's, derived from the scenario alone. ─────────────
+    assert_eq!(store.len(), 3, "three independent streams; positions not comparable across them");
+    for (id, sent, dropped) in [
+        (&id_a, &sent_a, &drop_a),
+        (&id_b, &sent_b, &drop_b),
+        (&id_c, &sent_c, &drop_c),
+    ] {
+        let log = views::merged_log(store.stream(id).unwrap());
+        assert_eq!(
+            structure(&log),
+            reference::merged_log(&surviving(sent, dropped)),
+            "merged log for {id} matches the oracle derived from the scenario"
+        );
+    }
+
+    // ── Targeted reads of the scenario's signature properties ──────────
+    let a_stored = store.stream(&id_a).unwrap();
+    let b_stored = store.stream(&id_b).unwrap();
+    let c_stored = store.stream(&id_c).unwrap();
+
+    // A: the carrier drop (t3) and the outage (t4–5) coalesce into one
+    // surfaced gap, then the stream resumes — without replaying history.
+    assert_eq!(a_stored.gap_spans(), vec![GapSpan { start: 3, end: 5 }], "A: one surfaced gap");
+    let finalize = a_stored.frames().last().unwrap();
+    assert_eq!(
+        LifecycleCost::decode(&finalize.payload).unwrap().phase,
+        "finalized",
+        "A's run ends with the finalize frame, delivered after the outage"
+    );
+
+    // B: its outage span (t4–5 emissions) is one surfaced gap; it resumes.
+    assert_eq!(b_stored.gap_spans().len(), 1, "B: a single outage gap");
+    assert!(b_stored.frames().count() > 5, "B resumed and kept producing after the outage");
+
+    // C: the dead node's stream ends at its last delivered frame — its
+    // outage-lost t4–5 frames are trailing loss (truncation), NOT a gap.
+    assert!(c_stored.gap_spans().is_empty(), "C: dead node truncates, no trailing gap");
+    assert_eq!(
+        c_stored.frames().last().unwrap().position,
+        Position(3),
+        "C ends at its last delivered position (t3)"
+    );
+}
diff --git a/crates/distribution/tests/t_datastream_realio.rs b/crates/distribution/tests/t_datastream_realio.rs
new file mode 100644
index 0000000..001b682
--- /dev/null
+++ b/crates/distribution/tests/t_datastream_realio.rs
@@ -0,0 +1,152 @@
+//! The two real-I/O checks that license trusting the offline work
+//! (`DATASTREAM_TESTING_SPEC.md` §9–§10).
+//!
+//! Every offline test in `t_datastream.rs` replaces the transport with a
+//! script. That substitution is honest only if the *real* transport never
+//! does anything the script cannot express. These two tests are the only
+//! ones that pay the cost of real I/O, and they are what convert "we
+//! reasoned about the transport" into "we verified it":
+//!
+//! * the **envelope-conformance check** (§9) sends a stream over a real
+//!   local socket and asserts the carrier never leaves the envelope —
+//!   whatever it delivers is a reordered subsequence of what was sent,
+//!   payloads byte-identical, positions intact. It asserts *no* delivery,
+//!   so loss is allowed and it cannot be flaky;
+//! * the **wiring smoke** (§10) stands a node and a consumer up over the
+//!   real socket and requires that *some* frames arrive and reconstruct —
+//!   proving the path is actually connected, not that it is complete.
+//!
+//! The "real transport" here is a loopback UDP datagram socket: real OS I/O,
+//! best-effort like the production carrier, carrying the very same
+//! [`encode_delivery`] envelope a deployed transport would. The production
+//! code under test is real throughout — the mux, the wire envelope, ingest,
+//! the store, and reconstruction; only the carrier is a local stand-in for
+//! the deployed one.
+
+#[path = "datastream_support/mod.rs"]
+mod support;
+
+use std::collections::{HashMap, HashSet};
+use std::net::UdpSocket;
+use std::time::Duration;
+
+use distribution::datastream::catalog::ProcStream;
+use distribution::datastream::frame::{Frame, Lifetime, NodeId, StreamId};
+use distribution::datastream::ingest::Consumer;
+use distribution::datastream::transport::Delivery;
+use distribution::datastream::wire::{decode_delivery, encode_delivery};
+
+use support::{payloads, Node};
+
+/// A realistic node stream, produced by the real mux.
+fn build_stream() -> (StreamId, Vec<Frame>) {
+    let id = StreamId::new(NodeId::new("node-real"), Lifetime(1));
+    let node = Node::new(id.clone());
+    node.emit(&payloads::identity("node-real", 1));
+    for tick in 0..20 {
+        node.emit(&payloads::resource(tick));
+    }
+    node.emit_text("trainer", ProcStream::Stdout, "epoch 1 complete");
+    node.emit(&payloads::membership("node-x", "alive", "suspect"));
+    (id, node.sent())
+}
+
+/// Carry a node's frames to a consumer over a real loopback UDP socket,
+/// each frame as one [`encode_delivery`] datagram, and return what the
+/// consumer actually received. Best-effort: send and receive errors are
+/// treated as loss, never as failures.
+fn carry_over_real_socket(stream: &StreamId, frames: &[Frame]) -> Vec<Delivery> {
+    let consumer = UdpSocket::bind("127.0.0.1:0").expect("bind consumer socket");
+    consumer.set_read_timeout(Some(Duration::from_millis(300))).expect("set timeout");
+    let consumer_addr = consumer.local_addr().expect("consumer addr");
+
+    let node = UdpSocket::bind("127.0.0.1:0").expect("bind node socket");
+    for frame in frames {
+        let datagram = encode_delivery(stream, frame);
+        // A send failure (e.g. a full socket buffer) is just loss.
+        let _ = node.send_to(&datagram, consumer_addr);
+    }
+
+    // Drain whatever is waiting; stop on the first read timeout.
+    let mut delivered = Vec::new();
+    let mut buf = vec![0u8; 64 * 1024];
+    loop {
+        match consumer.recv_from(&mut buf) {
+            Ok((n, _)) => {
+                if let Ok((s, frame)) = decode_delivery(&buf[..n]) {
+                    delivered.push(Delivery::new(s, frame));
+                }
+            }
+            Err(ref e)
+                if e.kind() == std::io::ErrorKind::WouldBlock
+                    || e.kind() == std::io::ErrorKind::TimedOut =>
+            {
+                break;
+            }
+            Err(_) => break,
+        }
+    }
+    delivered
+}
+
+/// §9 conformance — the real transport never leaves the envelope: whatever
+/// it delivers is a reordered subsequence of what was sent, byte-identical,
+/// positions intact. Asserts no specific delivery, so loss is tolerated and
+/// the test is not flaky.
+#[test]
+fn real_transport_stays_within_the_envelope() {
+    let (id, sent) = build_stream();
+    let delivered = carry_over_real_socket(&id, &sent);
+
+    let by_position: HashMap<u64, &Frame> = sent.iter().map(|f| (f.position.0, f)).collect();
+    let mut seen = HashSet::new();
+    for d in &delivered {
+        assert_eq!(d.stream, id, "the carrier did not alter the stream id");
+        let original = by_position
+            .get(&d.frame.position.0)
+            .expect("a delivered position was never sent — the carrier fabricated a frame");
+        assert_eq!(
+            &d.frame, *original,
+            "payload byte-identical, channel and position intact — no corruption or alteration"
+        );
+        assert!(seen.insert(d.frame.position.0), "no duplicate — a subsequence has no repeats");
+    }
+    // Deliberately no assertion on how many arrived: loss is within the
+    // envelope, so the check is sound without requiring delivery.
+}
+
+/// §10 wiring smoke — telemetry is actually plugged in: a node's stream,
+/// produced by the real mux and carried over a real socket, reaches a real
+/// consumer and reconstructs. Loose by design (best-effort): it requires
+/// *some* frames to arrive, not all, and tolerates loss and reorder.
+#[test]
+fn wiring_smoke_some_frames_arrive_and_reconstruct() {
+    let (id, sent) = build_stream();
+
+    // node (real mux output) → real socket → real ingest → store.
+    let delivered = carry_over_real_socket(&id, &sent);
+    let mut consumer = Consumer::new();
+    consumer.ingest(delivered);
+
+    let stored = consumer
+        .store()
+        .stream(&id)
+        .expect("the path is connected: the node's frames reached the consumer");
+    assert!(!stored.is_empty(), "some frames arrived over the real transport");
+
+    // Whatever arrived reconstructs correctly: each stored frame is the
+    // original at that position, and the store is in position order.
+    let by_position: HashMap<u64, &Frame> = sent.iter().map(|f| (f.position.0, f)).collect();
+    let mut prev: Option<u64> = None;
+    for frame in stored.frames() {
+        assert_eq!(
+            frame,
+            *by_position.get(&frame.position.0).expect("only sent frames arrive"),
+            "a reconstructed frame is the original, byte-identical"
+        );
+        if let Some(p) = prev {
+            assert!(frame.position.0 > p, "reconstructed in position order");
+        }
+        prev = Some(frame.position.0);
+    }
+}
diff --git a/crates/node/Cargo.toml b/crates/node/Cargo.toml
index 4b5af47..8533713 100644
--- a/crates/node/Cargo.toml
+++ b/crates/node/Cargo.toml
@@ -29,3 +29,7 @@ relay = ["iroh", "distribution/relay"]
 [[bin]]
 name = "swactor"
 path = "src/main.rs"
+
+[[bin]]
+name = "swactor-datastream-collector"
+path = "src/bin/swactor-datastream-collector.rs"
diff --git a/crates/node/src/bin/swactor-datastream-collector.rs b/crates/node/src/bin/swactor-datastream-collector.rs
new file mode 100644
index 0000000..88b0c5e
--- /dev/null
+++ b/crates/node/src/bin/swactor-datastream-collector.rs
@@ -0,0 +1,78 @@
+//! The datastream consumer, standalone: bind a UDP socket, decode every
+//! delivery that arrives, and print each frame to stdout the instant it lands.
+//!
+//! This is the "raw stream to stdout" end of the per-node telemetry datastream
+//! (see `distribution/DATASTREAM_SPEC.md`). It is deliberately the dumbest
+//! possible consumer: one datagram carries one frame
+//! ([`encode_delivery`](distribution::datastream::wire::encode_delivery)), so
+//! we decode and print in arrival order — loss and reorder show up as they
+//! happen on the wire, which is exactly what you want when watching a live
+//! cluster. No store, no views, no dashboard.
+//!
+//! Usage: `swactor-datastream-collector [--bind HOST:PORT]`
+//! (defaults to `$SWACTOR_DATASTREAM_BIND` or `0.0.0.0:7700`).
+
+use std::io::Write;
+use std::net::UdpSocket;
+
+use distribution::datastream::views::decode_body;
+use distribution::datastream::wire::decode_delivery;
+
+fn main() {
+    let bind = resolve_bind();
+    let sock = match UdpSocket::bind(&bind) {
+        Ok(s) => s,
+        Err(e) => {
+            eprintln!("datastream collector: failed to bind {bind}: {e}");
+            std::process::exit(1);
+        }
+    };
+    eprintln!("datastream collector listening on {bind} (one frame per datagram)");
+
+    // 64 KiB comfortably exceeds a UDP datagram; a frame never spans datagrams.
+    let mut buf = vec![0u8; 64 * 1024];
+    let stdout = std::io::stdout();
+    loop {
+        match sock.recv_from(&mut buf) {
+            Ok((n, _src)) => match decode_delivery(&buf[..n]) {
+                Ok((stream, frame)) => {
+                    let body = decode_body(&frame.channel, &frame.payload);
+                    let node = stream.node.as_str();
+                    let short = &node[..node.len().min(8)];
+                    let mut out = stdout.lock();
+                    // arrival order — no grouping, no buffering.
+                    let _ = writeln!(
+                        out,
+                        "{short}#{life} #{pos:<5} [{chan}] {body}",
+                        life = stream.life.0,
+                        pos = frame.position.0,
+                        chan = frame.channel,
+                    );
+                    let _ = out.flush();
+                }
+                Err(e) => eprintln!("datastream collector: dropped malformed datagram ({n} B): {e:?}"),
+            },
+            Err(e) => eprintln!("datastream collector: recv error: {e}"),
+        }
+    }
+}
+
+/// Resolve the bind address: `--bind HOST:PORT`, else `$SWACTOR_DATASTREAM_BIND`,
+/// else `0.0.0.0:7700`.
+fn resolve_bind() -> String {
+    let mut args = std::env::args().skip(1);
+    while let Some(arg) = args.next() {
+        match arg.as_str() {
+            "--bind" => {
+                if let Some(v) = args.next() {
+                    return v;
+                }
+            }
+            other if other.starts_with("--bind=") => {
+                return other["--bind=".len()..].to_string();
+            }
+            _ => {}
+        }
+    }
+    std::env::var("SWACTOR_DATASTREAM_BIND").unwrap_or_else(|_| "0.0.0.0:7700".to_string())
+}
diff --git a/crates/node/src/main.rs b/crates/node/src/main.rs
index f709de7..e4f5439 100644
--- a/crates/node/src/main.rs
+++ b/crates/node/src/main.rs
@@ -22,6 +22,14 @@ use distribution::peer_auth::PeerAllowList;
 use distribution::snapshot::DistributionNodeSnapshot;
 use distribution::swim::probe::SwimConfig;
 
+use distribution::datastream::catalog::{
+    self, ProcStream, Record, Role, RuntimeStats as DsRuntimeStats, TransportInternals,
+};
+use distribution::datastream::frame::{Lifetime, NodeId as DsNodeId, StreamId};
+use distribution::datastream::mux::Mux;
+use distribution::datastream::source::{self, CpuSampler, MembershipTracker};
+use distribution::datastream::wire::encode_delivery;
+
 use dashboard::collector::StatsCollector;
 use dashboard::{start_dashboard, DashboardConfig};
 
@@ -57,6 +65,19 @@ enum Subcmd {
         /// Invite code (base58-encoded node ID)
         code: String,
     },
+    /// Internal: a dummy child workload that prints lines forever.
+    ///
+    /// The node spawns itself with this subcommand as the "real process" each
+    /// node drives; its stdout/stderr are captured into the datastream's
+    /// `proc.<label>.{stdout,stderr}` channels. It runs until killed.
+    DummyWorkload {
+        /// Milliseconds between output lines
+        #[arg(long, default_value = "1000")]
+        interval_ms: u64,
+        /// Label used to name the process-output channels
+        #[arg(long, default_value = "workload")]
+        label: String,
+    },
 }
 
 #[derive(Parser)]
@@ -136,6 +157,40 @@ struct Args {
     /// Bind address for embedded relay server
     #[arg(long, default_value = "0.0.0.0")]
     relay_bind: String,
+
+    /// Relay host(s) for cluster discovery (repeatable). Overrides config.
+    #[arg(long)]
+    relay_hosts: Vec<String>,
+
+    /// Enable per-node telemetry datastream emission
+    #[arg(long)]
+    datastream: bool,
+
+    /// Ship datastream frames to this UDP collector (host:port). Implies --datastream.
+    #[arg(long)]
+    datastream_collector: Option<String>,
+
+    /// Region label reported in the datastream identity record
+    #[arg(long, default_value = "local")]
+    datastream_region: String,
+
+    /// Do not spawn the dummy child workload (whose output feeds proc.* channels)
+    #[arg(long)]
+    no_datastream_child: bool,
+
+    /// Label for the dummy child workload process
+    #[arg(long, default_value = "workload")]
+    datastream_child_label: String,
+}
+
+/// Datastream emission configuration, resolved from flags/env in `main`.
+struct DatastreamOpts {
+    enabled: bool,
+    collector: Option<String>,
+    region: String,
+    child: bool,
+    child_label: String,
+    life: u64,
 }
 
 // ── Dummy actor ──────────────────────────────────────────────────────────
@@ -260,6 +315,10 @@ fn main() {
                 install::uninstall();
                 return;
             }
+            Subcmd::DummyWorkload { interval_ms, label } => {
+                run_dummy_workload(*interval_ms, label);
+                return;
+            }
             Subcmd::Name { .. } | Subcmd::Invite | Subcmd::Join { .. } => {
                 /* handled after config/identity is loaded */
             }
@@ -350,7 +409,31 @@ fn main() {
     } else {
         cfg.relay_bind.unwrap_or_else(|| args.relay_bind.clone())
     };
-    let relay_hosts = cfg.relay_hosts.unwrap_or_default();
+    let relay_hosts = if !args.relay_hosts.is_empty() {
+        args.relay_hosts.clone()
+    } else {
+        cfg.relay_hosts.unwrap_or_default()
+    };
+
+    // Datastream telemetry options (all inert unless --datastream / --datastream-collector)
+    let datastream_enabled = args.datastream || args.datastream_collector.is_some();
+    let ds_opts = DatastreamOpts {
+        enabled: datastream_enabled,
+        collector: args.datastream_collector.clone(),
+        region: args.datastream_region.clone(),
+        child: datastream_enabled && !args.no_datastream_child,
+        child_label: args.datastream_child_label.clone(),
+        life: std::env::var("SWACTOR_LIFETIME")
+            .ok()
+            .and_then(|v| v.parse().ok())
+            .unwrap_or_else(|| {
+                std::time::SystemTime::now()
+                    .duration_since(std::time::UNIX_EPOCH)
+                    .map(|d| d.as_secs())
+                    .unwrap_or(0)
+            }),
+    };
+
     // Signal handler — second Ctrl+C forces immediate exit
     {
         let stop = Arc::clone(&stop);
@@ -609,6 +692,8 @@ fn main() {
         &relay_bind,
         relay_port,
         relay_hosts,
+        node_hex.clone(),
+        ds_opts,
     );
 
     #[cfg(not(feature = "iroh"))]
@@ -644,11 +729,16 @@ fn run_iroh(
     relay_bind: &str,
     relay_port: u16,
     relay_hosts: Vec<String>,
+    node_hex: String,
+    ds_opts: DatastreamOpts,
 ) {
     use distribution::iroh_driver::{IrohDriver, IrohDriverConfig};
     use iroh::{RelayMode, SecretKey};
     use swactor::std::RuntimeNaming;
 
+    // A node that was given no seed to join is the cluster's coordinator/seed.
+    let is_seed = seed_node_id.is_none();
+
     // Evaluate relay candidacy and determine embedded relay bind address
     #[cfg(feature = "relay")]
     let (embedded_relay_bind, relay_public_ip) = if relay_enabled {
@@ -792,6 +882,20 @@ fn run_iroh(
     dash.start_http(driver.tokio_handle());
     eprintln!("Dashboard at http://0.0.0.0:{dashboard_port}");
 
+    // Datastream telemetry: create the per-node mux, emit identity, spawn the
+    // dummy child workload, and prepare the UDP shipping socket.
+    let mut ds_rt = if ds_opts.enabled {
+        eprintln!(
+            "Datastream: enabled (collector: {}, region: {}, child: {})",
+            ds_opts.collector.as_deref().unwrap_or("<none>"),
+            ds_opts.region,
+            ds_opts.child,
+        );
+        Some(setup_datastream(&ds_opts, &node_hex, is_seed))
+    } else {
+        None
+    };
+
     // Main loop
     let mut round: u64 = 0;
     while !stop.load(Ordering::Relaxed) {
@@ -874,6 +978,62 @@ fn run_iroh(
         let mut snap = driver.snapshot();
         snap.node_name = Some(node_name.clone());
 
+        // Datastream emission: periodic samples (~1s), event-driven membership,
+        // then drain and ship every frame to the collector (one per datagram).
+        if let Some(ds) = ds_rt.as_mut() {
+            if round % 10 == 0 {
+                ds.mux.submit(
+                    catalog::HOST_RESOURCE,
+                    source::read_host_resource(&mut ds.cpu).encode(),
+                );
+
+                let rs = handle.runtime.stats();
+                let runtime_rec = DsRuntimeStats {
+                    actors_live: rs.actors.len() as u32,
+                    mailbox_depth: rs.workers.iter().map(|w| w.mailbox_depth as u32).sum(),
+                    scheduled_tasks: rs.workers.iter().map(|w| w.num_actors as u32).sum(),
+                };
+                ds.mux.submit(catalog::RUNTIME_STATS, runtime_rec.encode());
+
+                let transport = TransportInternals {
+                    relay_connected: driver.home_relay_url().is_some(),
+                    direct_peers: snap.members.iter().filter(|m| m.state == "alive").count() as u32,
+                    relay_peers: snap.members.iter().filter(|m| m.relay_url.is_some()).count() as u32,
+                    rtt_ms_p50: 0,
+                };
+                ds.mux.submit(catalog::TRANSPORT_INTERNALS, transport.encode());
+            }
+
+            // Key the membership view by the stable node id, not the friendly
+            // name: a peer's `node_name` resolves only after its metadata
+            // arrives, so keying on it would emit the same peer twice (once by
+            // id before the name is known, once by name after) and double-count
+            // it downstream. The id never changes; the consumer maps it to a
+            // friendly label for display.
+            let members: Vec<(String, String)> = snap
+                .members
+                .iter()
+                .map(|m| (m.node_id.clone(), m.state.clone()))
+                .collect();
+            for transition in ds.membership.diff(&members) {
+                ds.mux.submit(catalog::MEMBERSHIP, transition.encode());
+            }
+
+            // Drain unconditionally to bound the buffer; ship when we have a
+            // resolved collector address (re-resolve lazily if it was down).
+            let frames = ds.mux.drain();
+            if let Some(sock) = ds.udp.as_ref() {
+                if ds.collector_addr.is_none() && round % 10 == 0 {
+                    ds.collector_addr = ds.collector_spec.as_deref().and_then(resolve_addr);
+                }
+                if let Some(addr) = ds.collector_addr {
+                    for frame in &frames {
+                        let _ = sock.send_to(&encode_delivery(&ds.stream_id, frame), addr);
+                    }
+                }
+            }
+        }
+
         // Build rich invite code: <base58>#<addr1>,<addr2>@<relay_url>
         {
             let direct_addrs = driver.direct_addresses();
@@ -960,10 +1120,143 @@ fn run_iroh(
         thread::sleep(Duration::from_millis(100));
     }
 
+    // Stop the dummy child workload, if any.
+    if let Some(ds) = ds_rt.as_mut() {
+        if let Some(child) = ds.child.as_mut() {
+            let _ = child.kill();
+            let _ = child.wait();
+        }
+    }
+
     // Driver shutdown handles embedded relay cleanup automatically
     driver.shutdown();
 }
 
+// ── Datastream telemetry ───────────────────────────────────────────────────
+
+/// Live state a node carries to emit and ship its telemetry datastream.
+struct DatastreamRuntime {
+    stream_id: StreamId,
+    mux: Arc<Mux>,
+    udp: Option<std::net::UdpSocket>,
+    collector_addr: Option<std::net::SocketAddr>,
+    collector_spec: Option<String>,
+    cpu: CpuSampler,
+    membership: MembershipTracker,
+    child: Option<std::process::Child>,
+}
+
+/// Build the per-node datastream runtime: a mux keyed by this node's stream id,
+/// an immediate identity frame, the outgoing UDP socket, and the dummy child.
+fn setup_datastream(opts: &DatastreamOpts, node_hex: &str, is_seed: bool) -> DatastreamRuntime {
+    let stream_id = StreamId::new(DsNodeId::new(node_hex), Lifetime(opts.life));
+    let mux = Arc::new(Mux::new(stream_id.clone(), 4096));
+
+    // Identity is emitted first so the consumer can attribute the stream.
+    let role = if is_seed { Role::Coordinator } else { Role::Worker };
+    mux.submit(
+        catalog::IDENTITY,
+        source::identity_record(node_hex, role, &opts.region, opts.life).encode(),
+    );
+
+    let udp = if opts.collector.is_some() {
+        match std::net::UdpSocket::bind("0.0.0.0:0") {
+            Ok(s) => Some(s),
+            Err(e) => {
+                eprintln!("Datastream: failed to bind UDP socket: {e}");
+                None
+            }
+        }
+    } else {
+        None
+    };
+    let collector_addr = opts.collector.as_deref().and_then(resolve_addr);
+
+    let child = if opts.child {
+        spawn_workload_child(&mux, &opts.child_label)
+    } else {
+        None
+    };
+
+    DatastreamRuntime {
+        stream_id,
+        mux,
+        udp,
+        collector_addr,
+        collector_spec: opts.collector.clone(),
+        cpu: CpuSampler::new(),
+        membership: MembershipTracker::new(),
+        child,
+    }
+}
+
+/// Spawn the node binary as its own dummy child workload and pump the child's
+/// stdout/stderr into the mux as `proc.<label>.{stdout,stderr}` text frames.
+fn spawn_workload_child(mux: &Arc<Mux>, label: &str) -> Option<std::process::Child> {
+    use std::io::BufRead;
+    use std::process::{Command, Stdio};
+
+    let exe = std::env::current_exe().ok()?;
+    let mut child = Command::new(exe)
+        .arg("dummy-workload")
+        .arg("--label")
+        .arg(label)
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped())
+        .spawn()
+        .map_err(|e| eprintln!("Datastream: failed to spawn child workload: {e}"))
+        .ok()?;
+
+    if let Some(out) = child.stdout.take() {
+        let mux = Arc::clone(mux);
+        let channel = catalog::process_output(label, ProcStream::Stdout);
+        thread::spawn(move || {
+            for line in std::io::BufReader::new(out).lines().map_while(Result::ok) {
+                mux.submit(channel.clone(), line.into_bytes());
+            }
+        });
+    }
+    if let Some(err) = child.stderr.take() {
+        let mux = Arc::clone(mux);
+        let channel = catalog::process_output(label, ProcStream::Stderr);
+        thread::spawn(move || {
+            for line in std::io::BufReader::new(err).lines().map_while(Result::ok) {
+                mux.submit(channel.clone(), line.into_bytes());
+            }
+        });
+    }
+    Some(child)
+}
+
+/// Resolve a `host:port` collector spec to a single socket address.
+fn resolve_addr(spec: &str) -> Option<std::net::SocketAddr> {
+    use std::net::ToSocketAddrs;
+    spec.to_socket_addrs().ok()?.next()
+}
+
+/// The dummy child workload: print a line to stdout every `interval_ms`, and an
+/// occasional stderr line, until killed. This is the real OS process each node
+/// drives; its output is what flows on the datastream's `proc.*` channels.
+fn run_dummy_workload(interval_ms: u64, label: &str) {
+    use std::io::Write;
+    let interval = Duration::from_millis(interval_ms.max(1));
+    let mut n: u64 = 0;
+    loop {
+        n += 1;
+        {
+            let mut out = std::io::stdout().lock();
+            let _ = writeln!(out, "tick {n} — {label} working");
+            let _ = out.flush();
+        }
+        if n % 5 == 0 {
+            let mut err = std::io::stderr().lock();
+            let _ = writeln!(err, "warn: {label} synthetic backpressure at tick {n}");
+            let _ = err.flush();
+        }
+        thread::sleep(interval);
+    }
+}
+
 // ── Helpers ──────────────────────────────────────────────────────────────
 
 fn spawn_actors(
diff --git a/crates/node/src/plugins/distribution.rs b/crates/node/src/plugins/distribution.rs
index 184f4c6..5297b04 100644
--- a/crates/node/src/plugins/distribution.rs
+++ b/crates/node/src/plugins/distribution.rs
@@ -10,8 +10,9 @@ use dashboard::plugin::{DashboardPlugin, PluginResponse};
 use dashboard::JoinPeerInfo;
 use distribution::snapshot::DistributionNodeSnapshot;
 
-/// HTML page for the distribution plugin.
-const DISTRIBUTION_HTML: &str = include_str!("distribution_page.html");
+/// HTML page for the distribution plugin. Owned by the `dashboard` crate so the
+/// live node and the datastream dashboard serve the identical page.
+const DISTRIBUTION_HTML: &str = dashboard::DISTRIBUTION_PAGE_HTML;
 
 /// Dashboard plugin that exposes distribution node snapshots.
 pub struct DistributionPlugin {
diff --git a/tests/docker/DATASTREAM_DEMO.md b/tests/docker/DATASTREAM_DEMO.md
new file mode 100644
index 0000000..b0f41ec
--- /dev/null
+++ b/tests/docker/DATASTREAM_DEMO.md
@@ -0,0 +1,96 @@
+# Datastream demo cluster
+
+Spins up a small cluster of real `swactor` nodes in Docker, each driving a dummy
+child process, all shipping their per-node telemetry **datastream** to a single
+collector that prints the raw stream — live, frame-by-frame — to stdout.
+
+This is the "see the new metrics scheme working" demo. No dashboard; just the
+raw stream.
+
+## One-liner
+
+```sh
+./tests/docker/datastream-demo.sh
+```
+
+Builds everything, brings the cluster up in the foreground, and streams the raw
+datastream to your terminal. Ctrl-C tears it down. (Everything below is the
+manual breakdown of what that script does.)
+
+## What runs
+
+| Service     | Role                                                              |
+|-------------|-------------------------------------------------------------------|
+| `collector` | Binds UDP `:7700`, decodes each delivery, prints it on arrival    |
+| `relay`     | `swactor-iroh-relay` so nodes can find each other over the bridge |
+| `seed`      | Coordinator node (fixed identity), drives a dummy workload        |
+| `node-2/3`  | Worker nodes that join the seed, each drives a dummy workload      |
+
+Each node emits `identity` once, then `host.resource` / `runtime.stats` /
+`transport.internals` every ~1s, `membership` transitions as peers come and go,
+and its dummy child's stdout/stderr as `proc.workload.{stdout,stderr}`.
+
+## Run it
+
+From the repo root (the image is multi-stage — Docker compiles the binaries
+itself, so you need nothing on the host but Docker):
+
+```sh
+# 1. Build the images (first build compiles the workspace; later builds cache)
+#    and bring the cluster up in the foreground so the collector's stream is
+#    visible in the aggregated log.
+docker compose -f tests/docker/docker-compose.datastream.yml build
+docker compose -f tests/docker/docker-compose.datastream.yml up
+
+# 2. Ctrl-C to stop, then clean up:
+docker compose -f tests/docker/docker-compose.datastream.yml down
+```
+
+Watch the `collector-1 | ...` lines. Each is one frame:
+
+```
+collector-1  | e8d77206#1780337699 #0     [identity] {"node":"e8d7...","region":"seed","role":"coordinator",...}
+collector-1  | e8d77206#1780337699 #1     [proc.workload.stdout] tick 1 — workload working
+collector-1  | e8d77206#1780337699 #2     [host.resource] {"cpu_pct":3.5,"mem_total_mb":31741,"mem_used_mb":4019,...}
+collector-1  | e8d77206#1780337699 #3     [runtime.stats] {"actors_live":7,"mailbox_depth":0,"scheduled_tasks":7}
+collector-1  | e8d77206#1780337699 #4     [transport.internals] {"direct_peers":2,"relay_connected":true,...}
+collector-1  | e98b5ff5#1780337699 #7     [membership] {"from":"unknown","peer":"...","to":"alive"}
+```
+
+The prefix is `<node-id-prefix>#<lifetime>`; `#N` is the position within that
+node's stream (monotonic, gap-free at the source — gaps in the printed sequence
+mean datagrams were lost in transit, which is expected for a best-effort UDP
+carrier).
+
+## Local (non-Docker) version
+
+You don't need Docker to see the stream. Run a collector and a couple of nodes
+on localhost; they ship over loopback UDP:
+
+```sh
+cargo build -p node --bin swactor --bin swactor-datastream-collector
+
+./target/debug/swactor-datastream-collector --bind 127.0.0.1:7700 &
+
+./target/debug/swactor --identity-dir /tmp/dsA --dashboard-port 9101 --no-relay \
+    --datastream --datastream-collector 127.0.0.1:7700 --datastream-region A --actors 2 &
+./target/debug/swactor --identity-dir /tmp/dsB --dashboard-port 9102 --no-relay \
+    --datastream --datastream-collector 127.0.0.1:7700 --datastream-region B --actors 3 &
+```
+
+(Two standalone nodes with `--no-relay` and no seed won't discover each other,
+so `membership` stays quiet — that's expected. Every other channel streams.)
+
+## Flags
+
+| Flag                          | Meaning                                                  |
+|-------------------------------|----------------------------------------------------------|
+| `--datastream`                | Enable telemetry emission (off by default)               |
+| `--datastream-collector H:P`  | UDP collector address; implies `--datastream`            |
+| `--datastream-region R`       | Region label in the `identity` record                    |
+| `--no-datastream-child`       | Don't spawn the dummy child workload                     |
+| `--datastream-child-label L`  | Name for the `proc.<L>.*` channels (default `workload`)  |
+
+The lifetime discriminator is taken from `$SWACTOR_LIFETIME` if set, else the
+current UNIX seconds — bump it across restarts so a re-incarnated node starts a
+fresh stream.
diff --git a/tests/docker/Dockerfile.datastream b/tests/docker/Dockerfile.datastream
new file mode 100644
index 0000000..1f8033b
--- /dev/null
+++ b/tests/docker/Dockerfile.datastream
@@ -0,0 +1,37 @@
+# Datastream demo image (multi-stage, self-contained).
+#
+# The production image (../../Dockerfile) is `FROM scratch` over a static musl
+# binary. This demo image instead compiles the binaries *inside* Docker and
+# runs them on a slim glibc base. Building in the same Debian release as the
+# runtime keeps glibc versions matched, so the image is portable regardless of
+# the host's glibc — and you don't need a Rust toolchain on the host at all.
+#
+# Build context is the repo root (see docker-compose.datastream.yml). A
+# sibling Dockerfile.datastream.dockerignore keeps the build context to the
+# source tree (excludes target/, .git/).
+FROM rust:1-bookworm AS builder
+WORKDIR /src
+COPY . .
+RUN cargo build --release -p node -p distribution \
+    --bin swactor --bin swactor-datastream-collector --bin swactor-iroh-relay \
+    && cargo build --release -p dashboard --features datastream \
+    --bin swactor-datastream-dashboard
+
+FROM debian:bookworm-slim
+
+# ca-certificates is handy for iroh's default relays; harmless otherwise.
+RUN apt-get update && apt-get install -y --no-install-recommends ca-certificates \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY --from=builder /src/target/release/swactor /usr/local/bin/swactor
+COPY --from=builder /src/target/release/swactor-datastream-collector /usr/local/bin/swactor-datastream-collector
+COPY --from=builder /src/target/release/swactor-iroh-relay /usr/local/bin/swactor-iroh-relay
+COPY --from=builder /src/target/release/swactor-datastream-dashboard /usr/local/bin/swactor-datastream-dashboard
+
+# Bake the demo config and the fixed seed identity into the image so the
+# cluster is fully self-contained — no bind mounts (which are fragile across
+# daemon configurations). The seed identity is a throwaway demo key.
+COPY tests/docker/datastream-node.toml /etc/swactor/node.toml
+COPY tests/docker/identities/seed /seed-identity
+
+ENTRYPOINT ["swactor"]
diff --git a/tests/docker/Dockerfile.datastream.dockerignore b/tests/docker/Dockerfile.datastream.dockerignore
new file mode 100644
index 0000000..8e71885
--- /dev/null
+++ b/tests/docker/Dockerfile.datastream.dockerignore
@@ -0,0 +1,10 @@
+# Build context for the multi-stage datastream demo image. Unlike the root
+# .dockerignore (which excludes everything for the prebuilt-binary scratch
+# image), this build compiles from source inside Docker, so it needs the source
+# tree — just not the heavy build artifacts or VCS metadata.
+target
+**/target
+.git
+identity
+auth
+*.log
diff --git a/tests/docker/datastream-dashboard-demo.sh b/tests/docker/datastream-dashboard-demo.sh
new file mode 100755
index 0000000..f48dd60
--- /dev/null
+++ b/tests/docker/datastream-dashboard-demo.sh
@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+# Datastream demo, browser-dashboard edition: build, bring the cluster up, and
+# serve the live dashboard from the demuxed telemetry stream.
+#
+#   ./tests/docker/datastream-dashboard-demo.sh
+#
+# Same cluster and data as ./datastream-demo.sh — relay, seed, two workers, each
+# shipping its telemetry datastream — but the UDP sink is the HTTP dashboard
+# (swactor-datastream-dashboard) instead of the stdout collector. It demuxes the
+# frames and renders one node in the existing browser UI.
+#
+# Open the dashboard once the cluster is up (port printed below; default 18080).
+# Ctrl-C tears it down. Set DASH_PORT=<port> if the default host port is taken.
+# (First build is slow — it compiles the workspace; later runs are cached.)
+set -euo pipefail
+cd "$(dirname "$0")/../.."
+
+DASH_PORT="${DASH_PORT:-18080}"
+export DASH_PORT
+
+COMPOSE="docker compose \
+  -f tests/docker/docker-compose.datastream.yml \
+  -f tests/docker/docker-compose.datastream.dashboard.yml"
+
+$COMPOSE build
+trap '$COMPOSE down' EXIT INT TERM
+echo
+echo "  Dashboard:  http://localhost:${DASH_PORT}"
+echo
+$COMPOSE up
diff --git a/tests/docker/datastream-demo.sh b/tests/docker/datastream-demo.sh
new file mode 100755
index 0000000..598af8e
--- /dev/null
+++ b/tests/docker/datastream-demo.sh
@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+# One-liner datastream demo: build, bring the cluster up, stream to stdout.
+#
+#   ./tests/docker/datastream-demo.sh
+#
+# The image is multi-stage — Docker compiles the binaries inside the builder
+# stage, so you need nothing on the host but Docker. Brings the cluster up in
+# the foreground so the collector's live, frame-by-frame stream prints to your
+# terminal; Ctrl-C tears it back down. (First build is slow — it compiles the
+# workspace; later runs are cached.)
+set -euo pipefail
+cd "$(dirname "$0")/../.."
+
+COMPOSE="docker compose -f tests/docker/docker-compose.datastream.yml"
+
+$COMPOSE build
+trap '$COMPOSE down' EXIT INT TERM
+$COMPOSE up
diff --git a/tests/docker/datastream-node.toml b/tests/docker/datastream-node.toml
new file mode 100644
index 0000000..b642971
--- /dev/null
+++ b/tests/docker/datastream-node.toml
@@ -0,0 +1,6 @@
+# Minimal node config for the datastream demo cluster.
+# Keeps containers deterministic: no auth, no embedded relay, in-memory
+# datastore. Cluster discovery is driven by CLI flags in the compose file.
+dashboard_port = 9090
+relay = false
+auth = false
diff --git a/tests/docker/docker-compose.datastream.dashboard.yml b/tests/docker/docker-compose.datastream.dashboard.yml
new file mode 100644
index 0000000..4187284
--- /dev/null
+++ b/tests/docker/docker-compose.datastream.dashboard.yml
@@ -0,0 +1,25 @@
+# Dashboard overlay for the datastream demo.
+#
+# Use *together* with the base compose file so the same relay/seed/worker nodes
+# (and their telemetry) are the data source — only the sink changes. The base
+# `collector` service (which prints frames to stdout) is replaced by
+# `swactor-datastream-dashboard`, which binds the same UDP port (7700), demuxes
+# the per-node frames, and serves the live browser dashboard on :9090.
+#
+#   docker compose \
+#     -f tests/docker/docker-compose.datastream.yml \
+#     -f tests/docker/docker-compose.datastream.dashboard.yml up
+#
+# Then open http://localhost:18080. (Or just run ./tests/docker/datastream-dashboard-demo.sh)
+# Override the host port with DASH_PORT=<port> if 18080 is taken too.
+
+services:
+  collector:
+    entrypoint: ["swactor-datastream-dashboard"]
+    # Bind the same UDP sink the nodes ship to, serve the dashboard on :9090,
+    # and show the seed node. Drop --node to display the first node seen instead.
+    command: ["--bind", "0.0.0.0:7700", "--port", "9090", "--node", "seed"]
+    # Host port is overridable (DASH_PORT); defaults to 18080 since 9090 is a
+    # commonly-occupied port. Container port is always the dashboard's 9090.
+    ports:
+      - "${DASH_PORT:-18080}:9090"
diff --git a/tests/docker/docker-compose.datastream.yml b/tests/docker/docker-compose.datastream.yml
new file mode 100644
index 0000000..eff1818
--- /dev/null
+++ b/tests/docker/docker-compose.datastream.yml
@@ -0,0 +1,113 @@
+# Datastream demo cluster.
+#
+# A relay, a UDP collector, a seed swactor node, and two workers — every node
+# drives a dummy child process and ships its telemetry datastream to the
+# collector, whose stdout is the live, frame-by-frame raw stream.
+#
+# Run it (from the repo root), foreground so the collector's stream is visible:
+#
+#   cargo build --release -p node -p distribution \
+#       --bin swactor --bin swactor-datastream-collector --bin swactor-iroh-relay
+#   docker compose -f tests/docker/docker-compose.datastream.yml build
+#   docker compose -f tests/docker/docker-compose.datastream.yml up
+#
+# Watch the `collector-1 | ...` lines. Ctrl-C then `down` to clean up.
+#
+# Nodes converge over the standalone relay (10.0.3.2): each node runs with the
+# embedded relay off (--no-relay) and points --relay-hosts at the relay so iroh
+# selects RelayMode::Custom. The seed's node id below is baked from the
+# committed identity in ./identities/seed/node.key.json.
+
+x-node-build: &node-build
+  build:
+    context: ../..
+    dockerfile: tests/docker/Dockerfile.datastream
+
+services:
+  collector:
+    <<: *node-build
+    entrypoint: ["swactor-datastream-collector"]
+    command: ["--bind", "0.0.0.0:7700"]
+    networks:
+      datastream:
+        ipv4_address: 10.0.3.5
+
+  relay:
+    <<: *node-build
+    entrypoint: ["swactor-iroh-relay"]
+    command: ["--bind", "0.0.0.0:7843", "--public-host", "10.0.3.2"]
+    networks:
+      datastream:
+        ipv4_address: 10.0.3.2
+
+  seed:
+    <<: *node-build
+    command:
+      - "--config=/etc/swactor/node.toml"
+      - "--identity-dir=/seed-identity"
+      - "--no-relay"
+      - "--relay-port=7843"
+      - "--relay-hosts=10.0.3.2"
+      - "--datastream"
+      - "--datastream-collector=collector:7700"
+      - "--datastream-region=seed"
+      - "--actors=2"
+    networks:
+      datastream:
+        ipv4_address: 10.0.3.10
+    ports:
+      - "9091:9090"
+    depends_on:
+      - collector
+      - relay
+
+  node-2:
+    <<: *node-build
+    command:
+      - "--config=/etc/swactor/node.toml"
+      - "--seed-node-id=G2hRm2rWTFCqyeVnStJg72ysBiTvE19NTTPjdSEXhFK6"
+      - "--no-relay"
+      - "--relay-port=7843"
+      - "--relay-hosts=10.0.3.2"
+      - "--datastream"
+      - "--datastream-collector=collector:7700"
+      - "--datastream-region=worker"
+      - "--actors=3"
+    networks:
+      datastream:
+        ipv4_address: 10.0.3.11
+    ports:
+      - "9092:9090"
+    depends_on:
+      - collector
+      - relay
+      - seed
+
+  node-3:
+    <<: *node-build
+    command:
+      - "--config=/etc/swactor/node.toml"
+      - "--seed-node-id=G2hRm2rWTFCqyeVnStJg72ysBiTvE19NTTPjdSEXhFK6"
+      - "--no-relay"
+      - "--relay-port=7843"
+      - "--relay-hosts=10.0.3.2"
+      - "--datastream"
+      - "--datastream-collector=collector:7700"
+      - "--datastream-region=worker"
+      - "--actors=2"
+    networks:
+      datastream:
+        ipv4_address: 10.0.3.12
+    ports:
+      - "9093:9090"
+    depends_on:
+      - collector
+      - relay
+      - seed
+
+networks:
+  datastream:
+    driver: bridge
+    ipam:
+      config:
+        - subnet: 10.0.3.0/24
diff --git a/tests/docker/identities/seed/node.key.json b/tests/docker/identities/seed/node.key.json
new file mode 100644
index 0000000..1fe3181
--- /dev/null
+++ b/tests/docker/identities/seed/node.key.json
@@ -0,0 +1,3 @@
+{
+  "secret_key_hex": "539734dd2b487aaedec2b04300eacf9d6bf0feab7a5e2134956c8b8561a5b5d7"
+}
\ No newline at end of file