diff --git a/desktop/src-tauri/src/observed_unread.rs b/desktop/src-tauri/src/observed_unread.rs
index 45bbbbbcd..acc64ccf8 100644
--- a/desktop/src-tauri/src/observed_unread.rs
+++ b/desktop/src-tauri/src/observed_unread.rs
@@ -60,6 +60,13 @@ struct IngestEvent {
     counts_toward_app_badge: bool,
 }
 
+#[derive(Clone, Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+struct ChannelLatestUpdate {
+    channel_id: String,
+    created_at: u64,
+}
+
 #[derive(Clone, Debug, Deserialize, Serialize)]
 #[serde(rename_all = "camelCase")]
 struct MarkerUpdate {
@@ -101,6 +108,7 @@ pub(crate) struct IngestRequest {
     sequence: u64,
     base_revision: u64,
     events: Vec<IngestEvent>,
+    channel_latest: Vec<ChannelLatestUpdate>,
     markers: Vec<MarkerUpdate>,
     membership: Vec<MembershipUpdate>,
     clear_channels: Vec<String>,
@@ -179,6 +187,9 @@ fn open_db(path: &Path) -> Result<Connection, String> {
           counts_badge INTEGER NOT NULL, counts_app_badge INTEGER NOT NULL,
           PRIMARY KEY(scope,event_id));
         CREATE INDEX IF NOT EXISTS observed_events_channel ON observed_events(scope,channel_id,created_at,event_id);
+        CREATE TABLE IF NOT EXISTS channel_latest(
+          scope TEXT NOT NULL, channel_id TEXT NOT NULL, created_at INTEGER NOT NULL,
+          PRIMARY KEY(scope,channel_id));
         CREATE TABLE IF NOT EXISTS read_markers(
           scope TEXT NOT NULL, context_id TEXT NOT NULL, read_at INTEGER NOT NULL,
           PRIMARY KEY(scope,context_id));
@@ -292,6 +303,30 @@ fn projections(tx: &Transaction<'_>, scope: &str) -> Result<Vec<ChannelProjectio
         .map_err(|e| format!("query unread markers: {e}"))?
         .collect::<Result<_, _>>()
         .map_err(|e| format!("read unread markers: {e}"))?;
+    let mut by_channel: HashMap<String, ChannelProjection> = HashMap::new();
+    let mut latest_stmt = tx
+        .prepare("SELECT channel_id,created_at FROM channel_latest WHERE scope=?1")
+        .map_err(|e| format!("prepare channel latest: {e}"))?;
+    for row in latest_stmt
+        .query_map([scope], |r| {
+            Ok((r.get::<_, String>(0)?, r.get::<_, u64>(1)?))
+        })
+        .map_err(|e| format!("query channel latest: {e}"))?
+    {
+        let (channel_id, latest) = row.map_err(|e| format!("read channel latest: {e}"))?;
+        by_channel.insert(
+            channel_id.clone(),
+            ChannelProjection {
+                channel_id,
+                latest,
+                count: 0,
+                badge_count: 0,
+                app_badge_count: 0,
+                top_level_unread: false,
+                high_priority_unread: false,
+            },
+        );
+    }
     let mut stmt = tx.prepare("SELECT event_id,channel_id,created_at,root_id,high_priority,counts_badge,counts_app_badge FROM observed_events WHERE scope=?1 ORDER BY channel_id,created_at,event_id").map_err(|e| format!("prepare observed projection: {e}"))?;
     let rows = stmt
         .query_map([scope], |r| {
@@ -306,7 +341,6 @@ fn projections(tx: &Transaction<'_>, scope: &str) -> Result<Vec<ChannelProjectio
             ))
         })
         .map_err(|e| format!("query observed projection: {e}"))?;
-    let mut by_channel: HashMap<String, ChannelProjection> = HashMap::new();
     for row in rows {
         let (id, channel, created, root, high, badge, app) =
             row.map_err(|e| format!("read observed projection: {e}"))?;
@@ -353,7 +387,7 @@ pub(crate) fn observed_unread_open_scope(
         .map_err(|e| format!("begin observed-unread open: {e}"))?;
     let scope = request.scope.key();
     ensure_scope(&tx, &scope)?;
-    let (_, _, _, migration_complete, _) = state(&tx, &scope)?;
+    let (_, _, _, migration_complete, membership_seeded) = state(&tx, &scope)?;
     if !migration_complete {
         if let Some(payload) = &request.legacy_payload {
             if let Some(channels) = payload
@@ -377,8 +411,10 @@ pub(crate) fn observed_unread_open_scope(
         )
         .map_err(|e| format!("mark observed migration: {e}"))?;
     }
-    if let Some(seed) = &request.membership_seed {
-        seed_membership(&tx, &scope, seed)?;
+    if !membership_seeded {
+        if let Some(seed) = &request.membership_seed {
+            seed_membership(&tx, &scope, seed)?;
+        }
     }
     prune(&tx, &scope)?;
     let channels = projections(&tx, &scope)?;
@@ -440,6 +476,8 @@ pub(crate) fn observed_unread_ingest(
     if request.clear_all {
         tx.execute("DELETE FROM observed_events WHERE scope=?1", [&scope])
             .map_err(|e| format!("clear observed scope: {e}"))?;
+        tx.execute("DELETE FROM channel_latest WHERE scope=?1", [&scope])
+            .map_err(|e| format!("clear channel latest scope: {e}"))?;
     }
     for channel in &request.clear_channels {
         tx.execute(
@@ -447,10 +485,22 @@ pub(crate) fn observed_unread_ingest(
             params![scope, channel],
         )
         .map_err(|e| format!("clear observed channel: {e}"))?;
+        tx.execute(
+            "DELETE FROM channel_latest WHERE scope=?1 AND channel_id=?2",
+            params![scope, channel],
+        )
+        .map_err(|e| format!("clear channel latest: {e}"))?;
     }
     for event in &request.events {
         upsert_event(&tx, &scope, event)?;
     }
+    for update in &request.channel_latest {
+        tx.execute(
+            "INSERT INTO channel_latest(scope,channel_id,created_at) VALUES(?1,?2,?3) ON CONFLICT(scope,channel_id) DO UPDATE SET created_at=MAX(created_at,excluded.created_at)",
+            params![scope, update.channel_id, update.created_at],
+        )
+        .map_err(|e| format!("advance channel latest: {e}"))?;
+    }
     for update in &request.membership {
         if update.present {
             tx.execute(
@@ -577,6 +627,51 @@ mod tests {
         tx.commit().unwrap();
     }
     #[test]
+    fn latest_anchor_survives_without_a_notify_event_and_seed_is_one_shot() {
+        let (_d, mut conn) = db();
+        let tx = conn.transaction().unwrap();
+        let key = scope().key();
+        ensure_scope(&tx, &key).unwrap();
+        let first = MembershipSeed {
+            participated_root_ids: vec!["kept".into()],
+            ..Default::default()
+        };
+        seed_membership(&tx, &key, &first).unwrap();
+        let empty = MembershipSeed::default();
+        let (_, _, _, _, seeded) = state(&tx, &key).unwrap();
+        if !seeded {
+            seed_membership(&tx, &key, &empty).unwrap();
+        }
+        tx.execute(
+            "INSERT INTO channel_latest(scope,channel_id,created_at) VALUES(?1,'ch',42)",
+            [&key],
+        )
+        .unwrap();
+        let membership: i64 = tx
+            .query_row(
+                "SELECT COUNT(*) FROM unread_membership WHERE scope=?1 AND value='kept'",
+                [&key],
+                |r| r.get(0),
+            )
+            .unwrap();
+        assert_eq!(membership, 1);
+        let projected = projections(&tx, &key).unwrap();
+        assert_eq!(projected[0].latest, 42);
+        assert_eq!(projected[0].count, 0);
+    }
+    #[test]
+    fn ingest_request_wire_accepts_channel_latest() {
+        let request: IngestRequest = serde_json::from_value(serde_json::json!({
+            "scope":{"pubkey":"PK","relayUrl":"wss://relay/"},
+            "sequence":1,"baseRevision":0,"events":[],
+            "channelLatest":[{"channelId":"ch","createdAt":42}],
+            "markers":[],"membership":[],"clearChannels":[],"clearAll":false
+        }))
+        .unwrap();
+        assert_eq!(request.channel_latest[0].channel_id, "ch");
+        assert_eq!(request.channel_latest[0].created_at, 42);
+    }
+    #[test]
     fn serialized_response_matches_typescript_contract() {
         let actual = serde_json::to_value(ObservedUnreadResponse::Delta {
             scope: scope(),
diff --git a/desktop/src/features/channels/observedUnreadNative.test.mjs b/desktop/src/features/channels/observedUnreadNative.test.mjs
new file mode 100644
index 000000000..736ef628f
--- /dev/null
+++ b/desktop/src/features/channels/observedUnreadNative.test.mjs
@@ -0,0 +1,430 @@
+/**
+ * Native-mode tests for the observed-unread store.
+ *
+ * Every other suite in this directory runs with no `window.__TAURI_INTERNALS__`,
+ * so `invokeTauri` throws and the hook takes the localStorage fallback. That
+ * makes the whole native protocol untested — the first test here fails if the
+ * native path is not entered, so the rest cannot silently become tautologies.
+ */
+
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import {
+  installDOMShim,
+  installFreshStorage,
+  makeObservedEvent,
+  mountHook,
+  mountUnreadChannels,
+} from "./observedUnreadTestHarness.mjs";
+import {
+  installNativeRig,
+  makeStubRelayClient,
+} from "./observedUnreadNativeRig.mjs";
+
+installDOMShim();
+installFreshStorage();
+
+import { act } from "react";
+
+const RELAY = "wss://relay.example.com";
+const NOW_S = Math.floor(Date.now() / 1_000);
+
+const DEFAULT_PROPS = {
+  relay: RELAY,
+  isReady: true,
+  readStateVersion: 0,
+  getTs: () => null,
+  getOwn: () => null,
+};
+
+function makeRefs() {
+  return {
+    eventsRef: { current: new Map() },
+    latestRef: { current: new Map() },
+  };
+}
+
+/** Let the hook's promise chain settle (open/ingest are async). */
+async function settle() {
+  await act(async () => {
+    await new Promise((resolve) => setTimeout(resolve, 0));
+  });
+}
+
+// ── Entry: the boundary that makes every other test meaningful ────────────────
+
+test("native mode is ENTERED: the hook opens the scope over the bridge", async () => {
+  installFreshStorage();
+  let harness;
+  const rig = installNativeRig();
+  try {
+    harness = await mountHook(
+      { ...DEFAULT_PROPS, pubkey: "pk-entry" },
+      makeRefs(),
+    );
+    await settle();
+
+    assert.equal(
+      rig.requests("observed_unread_open_scope").length,
+      1,
+      "the hook must call observed_unread_open_scope — if this fails, the suite is measuring the localStorage fallback and every assertion below is vacuous",
+    );
+    assert.equal(
+      harness.api.isNative(),
+      true,
+      "isNative() must be true after a successful open",
+    );
+  } finally {
+    await harness?.unmount();
+    rig.restore();
+  }
+});
+
+test("native mode is NOT entered when the bridge fails, and the hook says so", async () => {
+  installFreshStorage();
+  let harness;
+  const rig = installNativeRig({
+    failCommands: new Set(["observed_unread_open_scope"]),
+  });
+  try {
+    harness = await mountHook(
+      { ...DEFAULT_PROPS, pubkey: "pk-entry-fail" },
+      makeRefs(),
+    );
+    await settle();
+
+    assert.equal(
+      harness.api.isNative(),
+      false,
+      "a failed open must leave the hook on the declared fallback path",
+    );
+  } finally {
+    await harness?.unmount();
+    rig.restore();
+  }
+});
+
+// ── D1: local mark-read must reach the native store ──────────────────────────
+
+test("D1: local markChannelRead sends a read marker to the native store", async () => {
+  installFreshStorage();
+  let harness;
+  const rig = installNativeRig();
+  try {
+    const PUBKEY = "pk-d1";
+    const CHANNEL = "channel-d1";
+    harness = await mountUnreadChannels({
+      pubkey: PUBKEY,
+      relay: RELAY,
+      channels: [{ id: CHANNEL, name: "d1", channelType: "stream" }],
+      relayClient: makeStubRelayClient(),
+    });
+    await settle();
+
+    const readAt = new Date(NOW_S * 1_000).toISOString();
+    await act(async () => {
+      harness.markChannelRead(CHANNEL, readAt);
+    });
+    await settle();
+
+    const markers = rig.markerUpdates();
+    assert.ok(
+      markers.some((marker) => marker.contextId === CHANNEL),
+      `local mark-read must reach observed_unread_ingest as a marker for ${CHANNEL}; saw ${JSON.stringify(markers)}`,
+    );
+  } finally {
+    await harness?.unmount();
+    rig.restore();
+  }
+});
+
+test("D1 control: the rig DOES record markers when syncMarkers is called directly", async () => {
+  installFreshStorage();
+  let harness;
+  const rig = installNativeRig();
+  try {
+    harness = await mountHook(
+      {
+        ...DEFAULT_PROPS,
+        pubkey: "pk-d1-control",
+        getTs: () => NOW_S,
+      },
+      makeRefs(),
+    );
+    await settle();
+
+    harness.api.syncMarkers(["channel-control"]);
+    await settle();
+
+    assert.deepEqual(
+      rig.markerUpdates(),
+      [{ contextId: "channel-control", readAt: NOW_S }],
+      "positive control: the marker path is observable through the rig, so a zero-marker result above means the code did not send one",
+    );
+  } finally {
+    await harness?.unmount();
+    rig.restore();
+  }
+});
+
+// ── D2: maxTrigger must survive in native mode ───────────────────────────────
+
+test("D2: a catch-up maxTrigger with no notifying event still advances native latest", async () => {
+  installFreshStorage();
+  const CHANNEL = "channel-d2";
+  const MAX_TRIGGER = NOW_S - 10;
+  let harness;
+  const rig = installNativeRig({
+    catchUpChannels: (request) =>
+      request.channels.map((channel) => ({
+        status: "success",
+        channelId: channel.id,
+        // The regression case: a trigger newer than the read marker that does
+        // NOT survive the notify filter, so it produces no observed event.
+        observedEvents: [],
+        maxTrigger: MAX_TRIGGER,
+        activityRows: [],
+        discovered: { participated: [], authored: [], mentioned: [] },
+      })),
+  });
+  try {
+    harness = await mountUnreadChannels({
+      pubkey: "pk-d2",
+      relay: RELAY,
+      channels: [{ id: CHANNEL, name: "d2", channelType: "stream" }],
+      relayClient: makeStubRelayClient(),
+    });
+    await settle();
+    await settle();
+
+    assert.equal(
+      rig.requests("unread_catch_up").length >= 1,
+      true,
+      "catch-up must have run for this assertion to mean anything",
+    );
+    assert.equal(
+      rig
+        .scope({ pubkey: "pk-d2", relayUrl: RELAY })
+        .channelLatest.get(CHANNEL),
+      MAX_TRIGGER,
+      `maxTrigger ${MAX_TRIGGER} must survive as the channel latest anchor even when no observed row is returned`,
+    );
+  } finally {
+    await harness?.unmount();
+    rig.restore();
+  }
+});
+
+// ── D3: an empty seed must not wipe accumulated native membership ────────────
+
+test("D3: reopening with an empty membership seed preserves discovered membership", async () => {
+  installFreshStorage();
+  let first;
+  let second;
+  const rig = installNativeRig();
+  const scope = { pubkey: "pk-d3", relayUrl: RELAY };
+  const emptySeed = {
+    participatedRootIds: [],
+    authoredRootIds: [],
+    mentionedRootIds: [],
+    followedRootIds: [],
+    mutedRootIds: [],
+    mutedChannelIds: [],
+  };
+  try {
+    first = await mountHook(
+      { ...DEFAULT_PROPS, pubkey: scope.pubkey, membershipSeed: emptySeed },
+      makeRefs(),
+    );
+    await settle();
+
+    // Catch-up discovery writes membership incrementally, as the commit
+    // message's ownership story describes.
+    first.api.updateMembership("participated", "root-discovered", true);
+    await settle();
+    assert.ok(
+      rig.scope(scope).membership.has("participated\u0000root-discovered"),
+      "precondition: discovery must have written membership natively",
+    );
+    await first.unmount();
+    first = null;
+
+    // Restart with an empty renderer seed (localStorage cleared / read failed).
+    second = await mountHook(
+      { ...DEFAULT_PROPS, pubkey: scope.pubkey, membershipSeed: emptySeed },
+      makeRefs(),
+    );
+    await settle();
+
+    assert.ok(
+      rig.scope(scope).membership.has("participated\u0000root-discovered"),
+      "an empty renderer seed must not delete membership the native store accumulated",
+    );
+  } finally {
+    await first?.unmount();
+    await second?.unmount();
+    rig.restore();
+  }
+});
+
+// ── Matrix rows that only became reachable once native mode was enterable ─────
+
+test("matrix: a replayed sequence is a no-op, not a second mutation", async () => {
+  installFreshStorage();
+  let harness;
+  const rig = installNativeRig();
+  const scope = { pubkey: "pk-replay", relayUrl: RELAY };
+  try {
+    harness = await mountHook(
+      { ...DEFAULT_PROPS, pubkey: scope.pubkey },
+      makeRefs(),
+    );
+    await settle();
+
+    harness.api.updateMembership("followed", "root-1", true);
+    await settle();
+    const afterFirst = rig.scope(scope).revision;
+
+    const replay = rig.requests("observed_unread_ingest").at(-1);
+    const response = await globalThis.window.__TAURI_INTERNALS__.invoke(
+      "observed_unread_ingest",
+      { request: replay },
+    );
+
+    assert.equal(
+      response.kind,
+      "snapshot",
+      "replay must return a snapshot, not a delta",
+    );
+    assert.equal(
+      rig.scope(scope).revision,
+      afterFirst,
+      "replaying an acked sequence must not advance the revision",
+    );
+  } finally {
+    await harness?.unmount();
+    rig.restore();
+  }
+});
+
+test("matrix: a sequence gap is rejected with snapshotRequired", async () => {
+  installFreshStorage();
+  let harness;
+  const rig = installNativeRig();
+  const scope = { pubkey: "pk-gap", relayUrl: RELAY };
+  try {
+    harness = await mountHook(
+      { ...DEFAULT_PROPS, pubkey: scope.pubkey },
+      makeRefs(),
+    );
+    await settle();
+
+    const current = rig.scope(scope);
+    const response = await globalThis.window.__TAURI_INTERNALS__.invoke(
+      "observed_unread_ingest",
+      {
+        request: {
+          scope,
+          sequence: current.lastSequence + 2,
+          baseRevision: current.revision,
+          events: [],
+          markers: [],
+          membership: [],
+          clearChannels: [],
+          clearAll: false,
+        },
+      },
+    );
+
+    assert.equal(response.kind, "snapshotRequired");
+    assert.equal(
+      rig.scope(scope).lastSequence,
+      current.lastSequence,
+      "a gap must not advance the ack",
+    );
+  } finally {
+    await harness?.unmount();
+    rig.restore();
+  }
+});
+
+test("matrix: an ingested event reaches the projection the badge reads", async () => {
+  installFreshStorage();
+  let harness;
+  const rig = installNativeRig();
+  const scope = { pubkey: "pk-project", relayUrl: RELAY };
+  try {
+    const refs = makeRefs();
+    harness = await mountHook({ ...DEFAULT_PROPS, pubkey: scope.pubkey }, refs);
+    await settle();
+
+    harness.api.schedule(
+      harness.api.currentScope,
+      "channel-p",
+      makeObservedEvent({ id: "evt-p", createdAt: NOW_S }),
+    );
+    harness.flushNative?.();
+    await act(async () => {
+      globalThis.dispatchEvent(
+        new (class extends Event {
+          constructor() {
+            super("pagehide");
+          }
+        })(),
+      );
+    });
+    await settle();
+
+    assert.equal(
+      harness.api.projectionsRef.current.get("channel-p")?.count,
+      1,
+      "the native projection must carry the ingested event",
+    );
+    assert.equal(harness.api.latestForChannel("channel-p"), NOW_S);
+  } finally {
+    await harness?.unmount();
+    rig.restore();
+  }
+});
+
+test("matrix: a rebuilt store generation is reopened instead of wedging on the old revision", async () => {
+  installFreshStorage();
+  let harness;
+  const rig = installNativeRig({
+    newGeneration: (() => {
+      let generation = 0;
+      return () => `gen-${++generation}`;
+    })(),
+  });
+  const scope = { pubkey: "pk-epoch", relayUrl: RELAY };
+  try {
+    harness = await mountHook(
+      { ...DEFAULT_PROPS, pubkey: scope.pubkey },
+      makeRefs(),
+    );
+    await settle();
+    harness.api.updateMembership("followed", "before-rebuild", true);
+    await settle();
+    assert.equal(
+      rig.scope(scope).revision,
+      1,
+      "precondition: renderer holds revision 1",
+    );
+
+    const rebuilt = rig.rebuildScope(scope);
+    harness.api.updateMembership("followed", "after-rebuild", true);
+    await settle();
+    await settle();
+
+    assert.equal(rebuilt.generation, "gen-2");
+    assert.ok(
+      rig.requests("observed_unread_open_scope").length >= 2,
+      "generation mismatch must reopen for a replacement snapshot",
+    );
+    assert.equal(harness.api.isNative(), true);
+  } finally {
+    await harness?.unmount();
+    rig.restore();
+  }
+});
diff --git a/desktop/src/features/channels/observedUnreadNativeRig.mjs b/desktop/src/features/channels/observedUnreadNativeRig.mjs
new file mode 100644
index 000000000..80b133b4f
--- /dev/null
+++ b/desktop/src/features/channels/observedUnreadNativeRig.mjs
@@ -0,0 +1,380 @@
+/**
+ * Fake native observed-unread store for tests.
+ *
+ * `invokeTauri` calls `window.__TAURI_INTERNALS__.invoke`, which does not exist
+ * under the Node test shim — so without this rig every mount silently takes the
+ * localStorage fallback and no test can enter the native path. Install this
+ * BEFORE mounting to make `observedPersistence.isNative()` true.
+ *
+ * The model mirrors `desktop/src-tauri/src/observed_unread.rs` closely enough to
+ * assert the protocol: one scope row (generation/revision/last_sequence/
+ * migration_complete/membership_seeded), observed events, read markers,
+ * membership, deterministic pruning, and the same projection fold. Keep the two
+ * in step — a divergence here is a test that certifies the wrong contract.
+ *
+ * Exported from a non-test file so the `src/**\/*.test.mjs` glob never picks it
+ * up as a suite.
+ */
+
+const HORIZON_SECONDS = 7 * 24 * 60 * 60;
+const PER_CHANNEL_CAP = 1_000;
+const GLOBAL_CAP = 5_000;
+
+const SEED_KINDS = [
+  ["participated", "participatedRootIds"],
+  ["authored", "authoredRootIds"],
+  ["mentioned", "mentionedRootIds"],
+  ["followed", "followedRootIds"],
+  ["muted_root", "mutedRootIds"],
+  ["muted_channel", "mutedChannelIds"],
+];
+
+/** Mirror of `ObservedUnreadScope::key` in observed_unread.rs. */
+function scopeKey(scope) {
+  return `${scope.pubkey.trim().toLowerCase()}:${scope.relayUrl
+    .trim()
+    .replace(/\/+$/, "")}`;
+}
+
+function validLegacyEvent(value, channelId) {
+  if (typeof value !== "object" || value === null) return null;
+  const { id, createdAt, rootId, highPriority } = value;
+  if (typeof id !== "string" || typeof createdAt !== "number") return null;
+  if (typeof highPriority !== "boolean") return null;
+  if (typeof value.countsTowardBadge !== "boolean") return null;
+  if (typeof value.countsTowardAppBadge !== "boolean") return null;
+  if (rootId !== null && rootId !== undefined && typeof rootId !== "string")
+    return null;
+  return {
+    channelId,
+    id,
+    createdAt,
+    rootId: rootId ?? null,
+    highPriority,
+    countsTowardBadge: value.countsTowardBadge,
+    countsTowardAppBadge: value.countsTowardAppBadge,
+  };
+}
+
+class Scope {
+  constructor(generation) {
+    this.generation = generation;
+    this.revision = 0;
+    this.lastSequence = 0;
+    this.migrationComplete = false;
+    this.membershipSeeded = false;
+    /** Map<eventId, event> — `ON CONFLICT(scope,event_id) DO NOTHING`. */
+    this.events = new Map();
+    /** Map<channelId, latest catch-up trigger>. */
+    this.channelLatest = new Map();
+    /** Map<contextId, readAt>. */
+    this.markers = new Map();
+    /** Set<`${kind}\u0000${value}`>. */
+    this.membership = new Set();
+  }
+
+  prune(nowSeconds) {
+    const cutoff = nowSeconds - HORIZON_SECONDS;
+    for (const [id, event] of this.events) {
+      if (event.createdAt <= cutoff) this.events.delete(id);
+    }
+    // Deterministic order, matching `ORDER BY created_at DESC, event_id DESC`.
+    const newestFirst = (a, b) =>
+      b.createdAt - a.createdAt || (a.id < b.id ? 1 : a.id > b.id ? -1 : 0);
+    const byChannel = new Map();
+    for (const event of this.events.values()) {
+      const bucket = byChannel.get(event.channelId) ?? [];
+      bucket.push(event);
+      byChannel.set(event.channelId, bucket);
+    }
+    for (const bucket of byChannel.values()) {
+      for (const event of bucket.sort(newestFirst).slice(PER_CHANNEL_CAP)) {
+        this.events.delete(event.id);
+      }
+    }
+    for (const event of [...this.events.values()]
+      .sort(newestFirst)
+      .slice(GLOBAL_CAP)) {
+      this.events.delete(event.id);
+    }
+  }
+
+  /** Mirror of `projections()`. */
+  projections() {
+    const marker = (key) => this.markers.get(key) ?? 0;
+    const byChannel = new Map(
+      [...this.channelLatest].map(([channelId, latest]) => [
+        channelId,
+        {
+          channelId,
+          latest,
+          count: 0,
+          badgeCount: 0,
+          appBadgeCount: 0,
+          topLevelUnread: false,
+          highPriorityUnread: false,
+        },
+      ]),
+    );
+    for (const event of this.events.values()) {
+      let readAt = Math.max(marker(event.channelId), marker(`msg:${event.id}`));
+      if (event.rootId)
+        readAt = Math.max(readAt, marker(`thread:${event.rootId}`));
+      if (event.createdAt <= readAt) continue;
+      const entry = byChannel.get(event.channelId) ?? {
+        channelId: event.channelId,
+        latest: 0,
+        count: 0,
+        badgeCount: 0,
+        appBadgeCount: 0,
+        topLevelUnread: false,
+        highPriorityUnread: false,
+      };
+      entry.latest = Math.max(entry.latest, event.createdAt);
+      entry.count += 1;
+      entry.badgeCount += event.countsTowardBadge ? 1 : 0;
+      entry.appBadgeCount += event.countsTowardAppBadge ? 1 : 0;
+      entry.topLevelUnread ||= !event.rootId;
+      entry.highPriorityUnread ||= event.highPriority;
+      byChannel.set(event.channelId, entry);
+    }
+    return [...byChannel.values()].sort((a, b) =>
+      a.channelId < b.channelId ? -1 : a.channelId > b.channelId ? 1 : 0,
+    );
+  }
+}
+
+/**
+ * Install the fake native bridge on `window.__TAURI_INTERNALS__`.
+ *
+ * Returns a handle for asserting against the store and the recorded IPC calls.
+ * Call `restore()` in a finally block (or let the next install replace it).
+ */
+export function installNativeRig(options = {}) {
+  const {
+    now = () => Math.floor(Date.now() / 1_000),
+    newGeneration = () => `gen-${Math.random().toString(16).slice(2)}`,
+    catchUpChannels = () => [],
+    failCommands = new Set(),
+  } = options;
+
+  const scopes = new Map();
+  const calls = [];
+  const previous = globalThis.window?.__TAURI_INTERNALS__;
+
+  const ensureScope = (key) => {
+    let scope = scopes.get(key);
+    if (!scope) {
+      scope = new Scope(newGeneration());
+      scopes.set(key, scope);
+    }
+    return scope;
+  };
+
+  const snapshot = (scope, request) => ({
+    kind: "snapshot",
+    scope: request.scope,
+    generation: scope.generation,
+    revision: scope.revision,
+    lastAckedSequence: scope.lastSequence,
+    migrationComplete: scope.migrationComplete,
+    membershipSeeded: scope.membershipSeeded,
+    channels: scope.projections(),
+  });
+
+  const openScope = (request) => {
+    const scope = ensureScope(scopeKey(request.scope));
+    if (!scope.migrationComplete) {
+      const channels = request.legacyPayload?.eventsByChannel;
+      if (channels && typeof channels === "object") {
+        for (const [channelId, events] of Object.entries(channels)) {
+          if (!Array.isArray(events)) continue;
+          for (const value of events) {
+            const event = validLegacyEvent(value, channelId);
+            if (event && !scope.events.has(event.id))
+              scope.events.set(event.id, event);
+          }
+        }
+      }
+      scope.migrationComplete = true;
+    }
+    if (!scope.membershipSeeded && request.membershipSeed) {
+      // The renderer seed establishes initial ownership once; subsequent opens
+      // preserve membership accumulated by native catch-up discovery.
+      scope.membership.clear();
+      for (const [kind, field] of SEED_KINDS) {
+        for (const value of request.membershipSeed[field] ?? []) {
+          scope.membership.add(`${kind}\u0000${value}`);
+        }
+      }
+      scope.membershipSeeded = true;
+    }
+    scope.prune(now());
+    return snapshot(scope, request);
+  };
+
+  const ingest = (request) => {
+    const scope = ensureScope(scopeKey(request.scope));
+    if (request.sequence <= scope.lastSequence) {
+      return {
+        ...snapshot(scope, request),
+        migrationComplete: true,
+        membershipSeeded: true,
+      };
+    }
+    if (
+      request.sequence !== scope.lastSequence + 1 ||
+      request.baseRevision !== scope.revision
+    ) {
+      return {
+        kind: "snapshotRequired",
+        scope: request.scope,
+        generation: scope.generation,
+        revision: scope.revision,
+        lastAckedSequence: scope.lastSequence,
+      };
+    }
+    const before = new Map(
+      scope.projections().map((item) => [item.channelId, item]),
+    );
+    if (request.clearAll) {
+      scope.events.clear();
+      scope.channelLatest.clear();
+    }
+    for (const channelId of request.clearChannels) {
+      scope.channelLatest.delete(channelId);
+      for (const [id, event] of scope.events) {
+        if (event.channelId === channelId) scope.events.delete(id);
+      }
+    }
+    for (const latest of request.channelLatest ?? []) {
+      scope.channelLatest.set(
+        latest.channelId,
+        Math.max(
+          scope.channelLatest.get(latest.channelId) ?? 0,
+          latest.createdAt,
+        ),
+      );
+    }
+    for (const event of request.events) {
+      if (!scope.events.has(event.id)) {
+        scope.events.set(event.id, { ...event, rootId: event.rootId ?? null });
+      }
+    }
+    for (const update of request.membership) {
+      const key = `${update.kind}\u0000${update.value}`;
+      if (update.present) scope.membership.add(key);
+      else scope.membership.delete(key);
+    }
+    for (const update of request.markers) {
+      if (update.readAt === null || update.readAt === undefined) {
+        scope.markers.delete(update.contextId);
+      } else {
+        scope.markers.set(
+          update.contextId,
+          Math.max(scope.markers.get(update.contextId) ?? 0, update.readAt),
+        );
+      }
+    }
+    scope.prune(now());
+    const after = scope.projections();
+    const afterIds = new Set(after.map((item) => item.channelId));
+    const baseRevision = scope.revision;
+    scope.revision += 1;
+    scope.lastSequence = request.sequence;
+    return {
+      kind: "delta",
+      scope: request.scope,
+      generation: scope.generation,
+      baseRevision,
+      revision: scope.revision,
+      ackedSequence: request.sequence,
+      upserts: after.filter(
+        (item) =>
+          JSON.stringify(before.get(item.channelId)) !== JSON.stringify(item),
+      ),
+      removed: [...before.keys()].filter((id) => !afterIds.has(id)),
+    };
+  };
+
+  const handlers = {
+    observed_unread_open_scope: (args) => openScope(args.request),
+    observed_unread_ingest: (args) => ingest(args.request),
+    unread_catch_up: (args) => ({
+      channels: catchUpChannels(args.request),
+    }),
+    // ReadStateManager reaches the bridge for signing/encryption. Serve inert
+    // values so a real manager can initialize without a Tauri host.
+    sign_event: (args) =>
+      JSON.stringify({
+        id: `signed-${calls.length}`,
+        pubkey: "rig-pubkey",
+        created_at: args.createdAt ?? now(),
+        kind: args.kind,
+        tags: args.tags,
+        content: args.content,
+        sig: "rig-sig",
+      }),
+    nip44_encrypt_to_self: (args) => args.plaintext,
+    nip44_decrypt_from_self: (args) => args.ciphertext,
+  };
+
+  const invoke = async (command, args = {}) => {
+    calls.push({ command, args });
+    if (failCommands.has(command)) {
+      throw new Error(`rig: ${command} configured to fail`);
+    }
+    const handler = handlers[command];
+    if (!handler) throw new Error(`rig: unhandled command ${command}`);
+    return handler(args);
+  };
+
+  if (typeof globalThis.window === "undefined") {
+    Object.defineProperty(globalThis, "window", {
+      value: globalThis,
+      configurable: true,
+    });
+  }
+  globalThis.window.__TAURI_INTERNALS__ = { invoke };
+
+  return {
+    calls,
+    /** Recorded requests for one command, in order. */
+    requests: (command) =>
+      calls
+        .filter((call) => call.command === command)
+        .map((call) => call.args.request),
+    /** Every marker update sent to the native store, flattened. */
+    markerUpdates: () =>
+      calls
+        .filter((call) => call.command === "observed_unread_ingest")
+        .flatMap((call) => call.args.request.markers),
+    scope: (scope) => scopes.get(scopeKey(scope)),
+    rebuildScope: (scope) => {
+      const rebuilt = new Scope(newGeneration());
+      rebuilt.migrationComplete = true;
+      rebuilt.membershipSeeded = true;
+      scopes.set(scopeKey(scope), rebuilt);
+      return rebuilt;
+    },
+    restore: () => {
+      if (previous === undefined) delete globalThis.window.__TAURI_INTERNALS__;
+      else globalThis.window.__TAURI_INTERNALS__ = previous;
+    },
+  };
+}
+
+/**
+ * Minimal RelayClient stand-in so a real ReadStateManager can initialize.
+ * `useReadState` returns no-op markers unless a relayClient is supplied, and a
+ * no-op `markContextRead` cannot exercise the local read path at all.
+ */
+export function makeStubRelayClient() {
+  return {
+    fetchEvents: async () => [],
+    fetchFirstEvent: async () => null,
+    subscribeLive: async () => async () => {},
+    subscribeToReconnects: () => () => {},
+    publishEvent: async (event) => event,
+  };
+}
diff --git a/desktop/src/features/channels/observedUnreadTestHarness.mjs b/desktop/src/features/channels/observedUnreadTestHarness.mjs
index da3cfa3e9..5ae2a393c 100644
--- a/desktop/src/features/channels/observedUnreadTestHarness.mjs
+++ b/desktop/src/features/channels/observedUnreadTestHarness.mjs
@@ -256,6 +256,7 @@ export async function mountHook(props, refs) {
     getTs,
     getOwn,
     onPruned,
+    membershipSeed,
   }) {
     apiRef.current = useObservedUnreadPersistence(
       pubkey,
@@ -266,7 +267,7 @@ export async function mountHook(props, refs) {
       getOwn,
       refs.eventsRef,
       refs.latestRef,
-      { onPruned: onPruned ?? (() => {}) },
+      { onPruned: onPruned ?? (() => {}), membershipSeed },
     );
     return null;
   }
@@ -311,6 +312,8 @@ export function seedStorage(pubkey, relay, channelId, eventId = "evt-1") {
 export async function mountUnreadChannels({
   pubkey,
   relay = "wss://relay.example.com",
+  channels = [],
+  relayClient,
 }) {
   const qc = new QueryClient({
     defaultOptions: { queries: { retry: false } },
@@ -318,13 +321,15 @@ export async function mountUnreadChannels({
 
   let capturedMarkChannelRead = null;
   let capturedMarkAllChannelsRead = null;
+  let capturedResult = null;
 
   function Inner({ pubkey: pk }) {
-    const result = useUnreadChannels([], null, {
+    const result = useUnreadChannels(channels, null, {
       pubkey: pk,
-      relayClient: undefined,
+      relayClient,
       relayUrl: relay,
     });
+    capturedResult = result;
     capturedMarkChannelRead = result.markChannelRead;
     capturedMarkAllChannelsRead = result.markAllChannelsRead;
     return null;
@@ -350,6 +355,9 @@ export async function mountUnreadChannels({
   await render(pubkey);
 
   return {
+    get result() {
+      return capturedResult;
+    },
     get markChannelRead() {
       return capturedMarkChannelRead;
     },
diff --git a/desktop/src/features/channels/useObservedUnreadPersistence.ts b/desktop/src/features/channels/useObservedUnreadPersistence.ts
index 6fb309fc6..d27a643b5 100644
--- a/desktop/src/features/channels/useObservedUnreadPersistence.ts
+++ b/desktop/src/features/channels/useObservedUnreadPersistence.ts
@@ -36,7 +36,11 @@ export type ObservedUnreadPersistence = {
   ) => void;
   removeChannel: (channelId: string) => void;
   updateMembership: (kind: string, value: string, present: boolean) => void;
-  syncMarkers: (contextIds: Iterable<string>) => void;
+  syncMarkers: (
+    contextIds: Iterable<string>,
+    explicitReadAt?: ReadonlyMap<string, number>,
+  ) => void;
+  advanceLatest: (channelId: string, createdAt: number) => void;
   latestForChannel: (channelId: string) => number | undefined;
   clearAll: () => void;
 };
@@ -201,6 +205,7 @@ export function useObservedUnreadPersistence(
           sequence: current.sequence + 1,
           baseRevision: current.revision,
           events,
+          channelLatest: [],
           markers: [],
           membership: [],
           clearChannels: [],
@@ -310,15 +315,19 @@ export function useObservedUnreadPersistence(
   }, [normalizedPubkey, normalizedRelayUrl]);
 
   const syncMarkers = React.useCallback(
-    (contextIds: Iterable<string>) => {
+    (
+      contextIds: Iterable<string>,
+      explicitReadAt?: ReadonlyMap<string, number>,
+    ) => {
       const state = nativeRef.current;
       if (!state) return;
       const markers = [...new Set(contextIds)].map((contextId) => ({
         contextId,
         readAt:
-          contextId.startsWith("thread:") || contextId.startsWith("msg:")
+          explicitReadAt?.get(contextId) ??
+          (contextId.startsWith("thread:") || contextId.startsWith("msg:")
             ? getOwnTimestamp(contextId)
-            : getEffectiveTimestamp(contextId),
+            : getEffectiveTimestamp(contextId)),
       }));
       if (markers.length === 0) return;
       flushNative();
@@ -335,6 +344,7 @@ export function useObservedUnreadPersistence(
           sequence: current.sequence + 1,
           baseRevision: current.revision,
           events: [],
+          channelLatest: [],
           markers,
           membership: [],
           clearChannels: [],
@@ -399,6 +409,7 @@ export function useObservedUnreadPersistence(
           sequence: current.sequence + 1,
           baseRevision: current.revision,
           events: [],
+          channelLatest: [],
           markers: [],
           membership: [],
           clearChannels,
@@ -410,6 +421,41 @@ export function useObservedUnreadPersistence(
     [apply, flushNative],
   );
 
+  // biome-ignore lint/correctness/useExhaustiveDependencies: mutable storage refs are stable containers
+  const advanceLatest = React.useCallback(
+    (channelId: string, createdAt: number) => {
+      const state = nativeRef.current;
+      if (!state) {
+        const current = latestByChannelRef.current.get(channelId) ?? 0;
+        if (createdAt > current)
+          latestByChannelRef.current.set(channelId, createdAt);
+        return;
+      }
+      flushNative();
+      chainRef.current = chainRef.current.then(() => {
+        const current = nativeRef.current;
+        if (
+          !current ||
+          current.scope.pubkey !== state.scope.pubkey ||
+          current.scope.relayUrl !== state.scope.relayUrl
+        )
+          return;
+        return ingestObservedUnread({
+          scope: current.scope,
+          sequence: current.sequence + 1,
+          baseRevision: current.revision,
+          events: [],
+          channelLatest: [{ channelId, createdAt }],
+          markers: [],
+          membership: [],
+          clearChannels: [],
+          clearAll: false,
+        }).then(apply);
+      });
+    },
+    [apply, flushNative],
+  );
+
   const updateMembership = React.useCallback(
     (kind: string, value: string, present: boolean) => {
       const state = nativeRef.current;
@@ -428,6 +474,7 @@ export function useObservedUnreadPersistence(
           sequence: current.sequence + 1,
           baseRevision: current.revision,
           events: [],
+          channelLatest: [],
           markers: [],
           membership: [{ kind, value, present }],
           clearChannels: [],
@@ -488,6 +535,7 @@ export function useObservedUnreadPersistence(
       removeChannel,
       updateMembership,
       syncMarkers,
+      advanceLatest,
       latestForChannel,
       clearAll,
     }),
@@ -499,6 +547,7 @@ export function useObservedUnreadPersistence(
       removeChannel,
       updateMembership,
       syncMarkers,
+      advanceLatest,
       latestForChannel,
       clearAll,
     ],
diff --git a/desktop/src/features/channels/useUnreadChannels.ts b/desktop/src/features/channels/useUnreadChannels.ts
index 40778305b..b956b672d 100644
--- a/desktop/src/features/channels/useUnreadChannels.ts
+++ b/desktop/src/features/channels/useUnreadChannels.ts
@@ -249,7 +249,6 @@ export function useUnreadChannels(
     mutedChannelIdsRef.current,
   );
 
-  // Persistence layer: hydration, pagehide flush, scope fence, write-through, marker-prune.
   const observedPersistence = useObservedUnreadPersistence(
     normalizedPubkey,
     normalizedRelayUrl,
@@ -265,7 +264,6 @@ export function useUnreadChannels(
     },
   );
 
-  // Forward only changed NIP-RS contexts; native owns the event read model.
   // biome-ignore lint/correctness/useExhaustiveDependencies: readStateVersion is the intentional drain trigger
   React.useEffect(() => {
     const advanced = drainSyncedAdvances();
@@ -350,11 +348,13 @@ export function useUnreadChannels(
       );
       if (markAt === null) return;
       markContextRead(channelId, markAt);
-      // Delegate destructive observed-ref removal to the fenced owner operation —
+      observedPersistence.syncMarkers(
+        [channelId],
+        new Map([[channelId, markAt]]),
+      );
       // the parent must not delete from latestByChannelRef or
       // observedUnreadEventsByChannelRef directly on the clear-observed path,
       // or a stale scope-A callback could corrupt scope B before the fence rejects.
-      // (Fenced record writes in handleChannelMessage and catch-up remain in the parent.)
       if (clearObserved) {
         observedPersistence.removeChannel(channelId);
         bumpLatestVersion();
@@ -721,11 +721,8 @@ export function useUnreadChannels(
           ) {
             const current =
               observedPersistence.latestForChannel(result.channelId) ?? 0;
-            if (
-              !observedPersistence.isNative() &&
-              result.maxTrigger > current
-            ) {
-              latestByChannelRef.current.set(
+            if (result.maxTrigger > current) {
+              observedPersistence.advanceLatest(
                 result.channelId,
                 result.maxTrigger,
               );
@@ -923,6 +920,7 @@ export function useUnreadChannels(
   unreadChannelIdsRef.current = unreadChannelIds;
 
   const markAllChannelsRead = React.useCallback(() => {
+    const marked = new Map<string, number>();
     for (const channelId of unreadChannelIdsRef.current) {
       delete forcedUnreadRef.current[channelId];
       const unixSeconds =
@@ -931,12 +929,13 @@ export function useUnreadChannels(
         null;
       if (unixSeconds !== null) {
         markContextRead(channelId, unixSeconds);
+        marked.set(channelId, unixSeconds);
       }
     }
+    observedPersistence.syncMarkers(marked.keys(), marked);
     if (pubkey) {
       forcedUnreadStore.write(pubkey, forcedUnreadRef.current);
     }
-    // Delegate destructive observed-ref clearing to the fenced owner operation —
     // the parent must not reset the observed Maps directly on this path, or a
     // stale scope-A callback could corrupt scope B before the fence rejects.
     // (Fenced record writes in handleChannelMessage and catch-up remain in the parent.)
diff --git a/desktop/src/shared/api/tauriObservedUnread.ts b/desktop/src/shared/api/tauriObservedUnread.ts
index 7a02ece72..73999aeae 100644
--- a/desktop/src/shared/api/tauriObservedUnread.ts
+++ b/desktop/src/shared/api/tauriObservedUnread.ts
@@ -64,6 +64,7 @@ export function ingestObservedUnread(request: {
   sequence: number;
   baseRevision: number;
   events: ObservedUnreadWireEvent[];
+  channelLatest: Array<{ channelId: string; createdAt: number }>;
   markers: Array<{ contextId: string; readAt: number | null }>;
   membership: Array<{ kind: string; value: string; present: boolean }>;
   clearChannels: string[];