fix: un rejet tardif ne ferme plus un canal vivant, un registre illisible ne perd plus toutes les inbox

packages/polyfill/src/emulated-verifier/branch-registers.ts

@@ -482,20 +482,73 @@ export async function readInboxCapsFor(doc: Nuri): Promise<Nuri | undefined> {
  */
 // @provenance myInboxes kind=aligned level=1 ref=engine/repo/src/types.rs:AddInboxCapV0 — the User branch answers 'which inboxes may I read'. The document-inbox half of this list is declared-not-wired — see `readInboxCapPairs`
 export async function myInboxes(): Promise<Nuri[]> {
+  const { inboxes, incomplete } = await enumerateMyInboxes();
+  // The whole list or the failure that stopped it — the contract this function has always
+  // had, and the one `connect.connectedUser` is built on: not knowing which queues exist is
+  // the session failing to establish, and a short list would silently leave a delivered
+  // share un-drained. The original error is re-thrown, not wrapped: its caller reads it.
+  if (incomplete !== null) throw incomplete.error;
+  return inboxes;
+}
+
+/**
+ * What could be listed of {@link myInboxes}, and whether that is ALL of it.
+ *
+ * `incomplete` is `null` when the list is whole, and otherwise carries what stopped the rest
+ * from being listed. Not an error CODE and not a flag on the array: the point is that a
+ * caller cannot read this answer without meeting the question "was there a failure", which
+ * is exactly what a short array on its own let everybody skip.
+ */
+export interface InboxEnumeration {
+  /** Every inbox this holder may read that COULD be listed — possibly not all of them. */
+  inboxes: Nuri[];
+  /** What stopped the rest from being listed, or `null` when nothing did. */
+  incomplete: { error: unknown } | null;
+}
+
+/**
+ * {@link myInboxes}, for the caller that can use a PARTIAL answer — the live observation.
+ *
+ * The list is built from two independent registers: the account record, which names the
+ * user's own two store inboxes, and the User branch, which names one per document it opened
+ * an inbox on. Built in one `try`, one unreachable register discarded BOTH halves — the two
+ * user inboxes were already in hand when the second read threw, and the throw dropped them
+ * on the floor. A broker hiccup spanning sign-in therefore left the identity connected with
+ * ZERO inboxes watched, not with the one register it could not reach missing: every deposit,
+ * including the ones addressed to the person by name, waited for the next connection.
+ *
+ * So each half answers for itself, and what came back is returned WITH the failure rather
+ * than instead of it. That is the line this package draws everywhere: reaching a register is
+ * infrastructure and may fail, but a failure must never come back looking like an absence —
+ * hence {@link InboxEnumeration.incomplete}, which the caller has to look at.
+ */
+export async function enumerateMyInboxes(): Promise<InboxEnumeration> {
   const holder = getCurrentUser();
-  if (holder === null) return [];
+  if (holder === null) return { inboxes: [], incomplete: null };
   const out: Nuri[] = [];
+  try {
     // BOTH of the user's inboxes — public and protected — since upstream a site carries
     // one on each of those two store repos (`engine/verifier/src/site.rs:127-152`).
     if ((await resolveAccount(holder)) !== null) {
-    for (const scope of ["public", "protected"] as const) out.push(await userInbox(holder, scope));
+      for (const scope of ["public", "protected"] as const) {
+        out.push(await userInbox(holder, scope));
       }
+    }
+  } catch (error) {
+    // The account record is what the other half reads THROUGH (`readInboxCapPairs` resolves
+    // the same record to find the private store), so there is no second half to attempt.
+    return { inboxes: out, incomplete: { error } };
+  }
+  try {
     for (const { inbox } of await readInboxCapPairs()) {
       // The record entitles this holder to read it — see the note above.
       fileOwnInbox(holder, inbox);
       out.push(inbox);
     }
-  return out;
+  } catch (error) {
+    return { inboxes: out, incomplete: { error } };
+  }
+  return { inboxes: out, incomplete: null };
 }
 
 /**

packages/polyfill/src/emulated-verifier/inbox-observer.ts

@@ -57,7 +57,7 @@
 
 import { getCaps, getCurrentUser } from "../shared-wallet/bootstrap";
 import { accessLogPrefix, logStage, shortNuri } from "../shared-wallet/access-log";
-import { myInboxes } from "./branch-registers";
+import { enumerateMyInboxes, type InboxEnumeration } from "./branch-registers";
 import { drainInboxSerially, drainsSettled } from "./inbox-drain";
 import { lookupAccount } from "../shared-wallet/account-registry";
 import { processInbox } from "../surface/inbox";
@@ -78,12 +78,6 @@ interface Observation {
   register: Unsubscribe | null;
   /** Unsubscribe from the held-caps change signal — the second "which inboxes" channel. */
   holdings: Unsubscribe | null;
-  /**
-   * The inboxes whose subscription has already been re-attempted once after failing to be
-   * OPENED. What bounds the repair below to one extra try per inbox, so a document the broker
-   * genuinely cannot serve costs two calls rather than a loop.
-   */
-  reattempted: Set<Nuri>;
   /** True while a re-enumeration is running, so its own effects do not restart it. */
   enumerating: boolean;
   /** A trigger that arrived mid-cycle: the running one repeats once rather than lose it. */
@@ -171,19 +165,35 @@ async function applyWhatArrived(obs: Observation, inbox: Nuri): Promise<void> {
  *
  * Never removes: the list only grows within a session (an `AddInboxCap` record is durable),
  * and dropping a subscription on a guess would silently stop applying an inbox.
+ *
+ * ── A list that came back SHORT still gets watched ────────────────────────
+ * `enumerateMyInboxes` and not `myInboxes`: the list is read from two independent registers
+ * and one of them being unreachable used to discard the other's answer too, so a broker
+ * hiccup spanning sign-in left the identity connected with ZERO inboxes watched rather than
+ * with one register's worth missing. Whatever came back is watched here and now — including,
+ * crucially, the user's own two inboxes, which are where a share addressed to a PERSON
+ * lands, and therefore the channel by which a read-only identity converges at all.
+ *
+ * The shortfall is reported, never passed over: an incomplete list is not a complete one,
+ * and the inboxes it is missing are watched on the next enumeration — which is what the
+ * register push and the holdings signal are for. Applying what lands in a user inbox is
+ * itself one of those signals (it files a cap), so the ordinary case repairs itself.
  */
 async function watchTheInboxes(obs: Observation): Promise<void> {
   if (!current(obs)) return;
-  let inboxes: Nuri[];
+  let listed: InboxEnumeration;
   try {
-    inboxes = await myInboxes();
+    listed = await enumerateMyInboxes();
   } catch (error) {
-    // Not knowing WHICH inboxes exist is the whole observation failing, not one queue.
+    // Not knowing WHICH inboxes exist AT ALL is the whole observation failing, not one queue.
     reportUnobserved("the inboxes to watch could not be listed", error);
     return;
   }
   if (!current(obs)) return;
-  for (const inbox of inboxes) {
+  if (listed.incomplete !== null) {
+    reportUnobserved("the inboxes to watch could not all be listed", listed.incomplete.error);
+  }
+  for (const inbox of listed.inboxes) {
     if (obs.inboxes.has(inbox)) continue;
     try {
       // The push is the signal; the drain is the work. The FIRST push is the initial
@@ -212,20 +222,28 @@ async function watchTheInboxes(obs: Observation): Promise<void> {
 }
 
 /**
- * The subscription on `inbox` could not be OPENED — report it, forget it, and try once more.
+ * The subscription on `inbox` could not be OPENED — report it, and forget it.
  *
  * **Forget it**, because the entry this observation holds is the whole record of "already
  * watched": leaving a dead one in place is how one rejection at connection turned into a
  * session-long silence. Removed, the next enumeration subscribes again as if it had never
  * been attempted.
  *
- * **Try once more**, because the usual cause is a repo the verifier has not synced yet, and
+ * ── And that is ALL it does: recovery waits for the next SIGNAL ───────────
- * the whole cost of finding out is one call. Exactly one extra attempt per inbox, tracked in
+ * Until 2026-08-17 this also re-enumerated on the spot, once per inbox. That call runs
- * {@link Observation.reattempted}: a broker that genuinely cannot serve this document must
+ * synchronously out of the very rejection it is reacting to, so it asks the broker that has
- * not be asked again and again by a loop that has no reason to stop. If the second attempt
+ * just refused, in the same turn, with nothing having changed — and spends the one extra
- * fails too, the failure has been reported twice and the inbox waits for the next
+ * attempt it was allowed doing it. Deleting it left the whole suite green, which is the
- * enumeration signal — or for the next connection, where an unapplied deposit has always
+ * measure of what it achieved.
- * waited.
+ *
+ * What actually repairs this is an event, and this module already listens to the two that
+ * exist: the register push (`watchTheRegister`) and the held-caps signal
+ * (`CapRegistry.onChange`), each of which re-enters {@link enumerate} and finds this inbox
+ * unwatched. Applying anything at all fires the second one, so a session that is doing
+ * something catches up on its own. A session that is doing nothing waits for its next
+ * connection — where an unapplied deposit has always waited, since an inbox is not consumed
+ * by being unread. Polling for it is ruled out here for the same reason it is in
+ * `inbox-processor.ts`: this regime is push-driven, and a timer is what it replaced.
  */
 function watchFailed(obs: Observation, inbox: Nuri, error: unknown): void {
   if (!current(obs)) return;
@@ -239,9 +257,6 @@ function watchFailed(obs: Observation, inbox: Nuri, error: unknown): void {
     }
   }
   reportUnobserved("this inbox could not be watched: " + shortNuri(inbox), error);
-  if (obs.reattempted.has(inbox)) return;
-  obs.reattempted.add(inbox);
-  track(obs, enumerate(obs));
 }
 
 /**
@@ -337,7 +352,6 @@ export async function startObservingInboxes(): Promise<void> {
     inboxes: new Map(),
     register: null,
     holdings: null,
-    reattempted: new Set(),
     enumerating: false,
     enumerateAgain: false,
     pending: new Set(),

packages/polyfill/src/surface/subscribe.ts

@@ -175,12 +175,26 @@ interface DocFanOut {
    * It therefore stays true once the setup has SUCCEEDED: the attempt still stands.
    *
    * Cleared on the two ways the attempt stops standing: the last listener leaving
-   * ({@link releaseFanOut}), and a setup that FAILED ({@link reportSetupFailure}). Left true
+   * ({@link releaseFanOut}), and the CURRENT setup FAILING ({@link reportSetupFailure}). Left
-   * on failure it stopped meaning "one is already running" and started meaning "this NURI is
+   * true on failure it stopped meaning "one is already running" and started meaning "this NURI
-   * finished" — no later joiner ever attempted it again, for the whole session, over one
+   * is finished" — no later joiner ever attempted it again, for the whole session, over one
    * transient rejection.
    */
   establishing: boolean;
+  /**
+   * WHICH establish this fan-out is waiting on — bumped by {@link beginEstablish} every time
+   * one is kicked off, and captured by that call for the whole of its life.
+   *
+   * Two establishes can be in flight over the SAME entry: {@link resubscribeDocs} re-opens the
+   * channel of a fan-out whose first attempt has not settled yet, and it re-opens it on the
+   * entry rather than on a fresh one, precisely so the listeners are kept. So `entry` identity
+   * — the only currency this module had — answers "is this fan-out still the one for this
+   * NURI", and cannot answer "is this attempt still the one this fan-out is waiting on". A
+   * counter can, and that second question is the one a LATE outcome has to ask: the first
+   * attempt rejecting long after the second SUCCEEDED is not this document failing, it is one
+   * superseded call finally answering.
+   */
+  attempt: number;
   /**
    * The most recent `State` push, replayed to a listener that joins later.
    * Its own `doc_subscribe` would have pushed one; the fan-out owes it the same.
@@ -216,6 +230,25 @@ function fanOut(nuri: Nuri, entry: DocFanOut, resp: DocChange, type: DocChangeTy
   }
 }
 
+/** Is `attempt` still the establish this fan-out is waiting on? */
+function isCurrentAttempt(nuri: Nuri, entry: DocFanOut, attempt: number): boolean {
+  return fanOuts.get(nuri) === entry && entry.attempt === attempt;
+}
+
+/**
+ * Kick off the one real subscription for `entry` — the ONLY way an establish is started.
+ *
+ * It stamps the attempt (see {@link DocFanOut.attempt}) as it starts it, so an outcome that
+ * arrives late can tell whether it is still the one being waited on. Being the only door is
+ * what makes that true: a second call site that forgot to bump the counter would hand its
+ * establish the number of the one it just superseded.
+ */
+function beginEstablish(nuri: Nuri, entry: DocFanOut, ng: { doc_subscribe?: unknown }): void {
+  entry.establishing = true;
+  entry.attempt += 1;
+  void establish(nuri, entry, ng, entry.attempt);
+}
+
 /**
  * The one real subscription could not be OPENED: forget the attempt, and say so.
  *
@@ -226,11 +259,24 @@ function fanOut(nuri: Nuri, entry: DocFanOut, resp: DocChange, type: DocChangeTy
  * **Visible** — the log always, plus the callers who asked to be told, so a caller whose job
  * depends on the subscription (the inbox observation) can report it and try again rather
  * than sit on a dead entry.
+ *
+ * ── Only for the attempt still being WAITED ON ─────────────────────────────
+ * Both halves act on the fan-out as it stands NOW, so a SUPERSEDED attempt must do neither.
+ * A rejection that arrives after {@link resubscribeDocs} has already re-opened the channel is
+ * not this document failing — the channel is open and pushing. Told anyway, the inbox
+ * observation dropped its entry and released it, which closed the WORKING subscription,
+ * printed "this inbox could not be watched" about an inbox that was, and left the identity
+ * with a silent queue. Clearing `establishing` was the same mistake one level down: it says
+ * "nothing is running" while the second attempt is, so the next joiner opens a third — and a
+ * second `doc_subscribe` on a branch EVICTS the one before it.
+ *
+ * Superseded, it is therefore LOGGED and nothing else: the call that replaced it owns the
+ * outcome, and reports its own failure if it has one.
  */
-function reportSetupFailure(nuri: Nuri, entry: DocFanOut, error: unknown): void {
+function reportSetupFailure(nuri: Nuri, entry: DocFanOut, error: unknown, attempt: number): void {
   console.error("[subscribe] doc_subscribe failed for", nuri, error);
+  if (!isCurrentAttempt(nuri, entry, attempt)) return;
   entry.establishing = false;
-  if (fanOuts.get(nuri) !== entry) return;
   for (const listener of [...entry.listeners]) {
     const tell = listener.onSetupFailed;
     if (tell === null || !entry.listeners.has(listener)) continue;
@@ -262,7 +308,12 @@ function releaseFanOut(nuri: Nuri, entry: DocFanOut): void {
  * Errors are isolated to this document (they never reject a shared batch — see
  * {@link subscribeDocs}); a failed setup simply leaves the document silent.
  */
-async function establish(nuri: Nuri, entry: DocFanOut, ng: { doc_subscribe?: unknown }): Promise<void> {
+async function establish(
+  nuri: Nuri,
+  entry: DocFanOut,
+  ng: { doc_subscribe?: unknown },
+  attempt: number,
+): Promise<void> {
   // No reactive primitive on the injected `ng` (the fake in the unit suite): there is
   // nothing to call, so this document simply never pushes — the same documented no-op
   // `openRepoUnguarded` takes for the same injection, and not a failure to report. A real
@@ -287,7 +338,7 @@ async function establish(nuri: Nuri, entry: DocFanOut, ng: { doc_subscribe?: unk
     }
     entry.realUnsub = typeof unsub === "function" ? unsub : null;
   } catch (error) {
-    reportSetupFailure(nuri, entry, error);
+    reportSetupFailure(nuri, entry, error, attempt);
   }
 }
 
@@ -345,8 +396,7 @@ export function resubscribeDocs(): void {
         console.error("[subscribe] unsubscribe failed for", nuri, error);
       }
     }
-    entry.establishing = true;
+    beginEstablish(nuri, entry, ng);
-    void establish(nuri, entry, ng);
   }
 }
 
@@ -422,7 +472,13 @@ export function subscribeDocUnguarded(
 
   let entry = fanOuts.get(nuri);
   if (!entry) {
-    entry = { listeners: new Set(), realUnsub: null, establishing: false, lastState: null };
+    entry = {
+      listeners: new Set(),
+      realUnsub: null,
+      establishing: false,
+      attempt: 0,
+      lastState: null,
+    };
     fanOuts.set(nuri, entry);
   }
   const joined = entry;
@@ -443,8 +499,7 @@ export function subscribeDocUnguarded(
   }
 
   if (!joined.establishing) {
-    joined.establishing = true;
+    beginEstablish(nuri, joined, ng as { doc_subscribe?: unknown });
-    void establish(nuri, joined, ng as { doc_subscribe?: unknown });
   }
 
   let stopped = false;

packages/polyfill/test/continuous-inbox-observation.test.ts

@@ -35,6 +35,7 @@ import { resolveAccount, userInbox } from "../src/shared-wallet/account-registry
 import { observationSettled } from "../src/emulated-verifier/inbox-observer";
 import { cancelScheduledInboxProcessing } from "../src/emulated-verifier/inbox-processor";
 import { connectedUser } from "../src/emulated-verifier/connect";
+import { enumerateMyInboxes, myInboxes } from "../src/emulated-verifier/branch-registers";
 import { setOpenTimeoutForTests } from "../src/emulated-verifier/open-repo";
 import { bootPage, forgetEverything, signIn, type FakeWallet, type Quad } from "./wallet-fake";
 import type { Nuri } from "../src/model/types";
@@ -353,7 +354,7 @@ describe("a deposit that cannot be applied", () => {
     expect(getCaps().capForHolder("alice", first.doc)).toBeDefined();
   });
 
-  test("because its inbox could not be WATCHED is reported, and attempted again", async () => {
+  test("because its inbox could not be WATCHED is reported, and the next signal re-attempts it", async () => {
     const { doc, inTransit } = await bobSharesWithAlice();
     const aliceInbox = await userInbox("alice", "protected");
 
@@ -387,9 +388,14 @@ describe("a deposit that cannot be applied", () => {
     await converge();
     expect(getCaps().capForHolder("alice", doc)).toBeUndefined();
 
-    // The broker recovers and Alice does something ordinary. The inbox that could not be
+    // The broker recovers and Alice does something ordinary — which is a SIGNAL, not a
-    // opened was not written off for the session: it is subscribed to on the next
+    // coincidence: creating anything files caps, and the held-caps channel re-enters the
-    // enumeration, and its initial push finds the deposit still waiting.
+    // enumeration. That is the whole of the repair, and it is deliberately the whole of it:
+    // a re-attempt fired from the rejection itself asks the broker that has just refused, in
+    // the same turn, with nothing having changed. The inbox that could not be opened was not
+    // written off for the session — the failed entry is forgotten, so this enumeration
+    // subscribes again as if it had never been attempted, and the initial push of that new
+    // subscription finds the deposit still waiting.
     refusing = false;
     await storeRegistry.createEntityDoc("protected");
     await converge();
@@ -422,18 +428,30 @@ describe("a deposit that cannot be applied", () => {
 });
 
 describe("a connection whose own work FAILED", () => {
-  test("still leaves the identity watched — being connected is what is observed", async () => {
+  /**
+   * Aimed at the PRIVATE store, and that is the whole test.
+   *
+   * It used to fail reads on `docPublic`, which makes the restore reject and leaves the
+   * enumeration of the inboxes untouched — so it proved that watching survives a failure that
+   * was never going to threaten it. The private store is the one the connection restores from
+   * AND the register that says which inboxes exist, so failing it is the case that actually
+   * decides: listing the inboxes reads it, and one throw used to discard the two user inboxes
+   * that had ALREADY been listed before it. The identity was then connected with nothing
+   * watched at all, and a person who only reads — who never creates anything, so never fires
+   * a signal — had no way back for the rest of the session.
+   */
+  test("still leaves the identity watched — including when the failing store is the register", async () => {
     const { doc, inTransit } = await bobSharesWithAlice();
-    // The broker cannot answer for one of Alice's own stores, so the RESTORE fails and the
+    // The broker cannot answer for Alice's private store, so the RESTORE fails and the
     // connection rejects. She is connected regardless: `setCurrentUser` is synchronous and
     // took effect before any of this ran, and nothing signs her back out.
-    const store = (await resolveAccount("alice"))?.docPublic;
+    const store = (await resolveAccount("alice"))?.docPrivate;
-    if (store === undefined) throw new Error("the fixture did not give Alice a public store");
+    if (store === undefined) throw new Error("the fixture did not give Alice a private store");
     fake._failReadsOn.add(store);
 
     setCurrentUser("alice");
     let rejected = false;
-    await whileWatchingTheLog(async () => {
+    const reported = await whileWatchingTheLog(async () => {
       try {
         await connectedUser();
       } catch {
@@ -444,17 +462,86 @@ describe("a connection whose own work FAILED", () => {
     // The caller is still TOLD, and that rule is not what changes here: failing to reach the
     // registers rejects, exactly as before.
     expect(rejected).toBe(true);
+    // …and so is the log, about the half of the list that could not be read. A short list
+    // that says nothing is a failure wearing the face of an absence, which is the one thing
+    // this package will not do — the inboxes it names are watched, the ones it does not are
+    // owed a next enumeration, and both facts have to be legible.
+    expect(reported.filter((l) => /could not all be listed/.test(l)).length).toBeGreaterThan(0);
+    expect(reported.find((l) => /could not all be listed/.test(l))).toContain("[alice][polyfill]");
 
-    // The hiccup passes. Alice never touched the page.
+    // The hiccup passes. Alice never touched the page — no sign-in, no document created,
+    // nothing that could stand in for the watching she is owed.
     fake._failReadsOn.delete(store);
     fake._deliver(inTransit);
     await converge();
 
     // What she is owed is not the restore she lost — it is that a deposit made while she sits
-    // there converges. Watching used to be the LAST line of the connection work, so a restore
+    // there converges. Her own two inboxes are where a share addressed to her by NAME lands,
-    // that rejected skipped it and left her connected with nothing observing her inboxes: one
+    // and they were listed before the register threw; watching them is what makes this
-    // hiccup at sign-in, and every share made afterwards was lost to her for the session.
+    // session behave like every other one.
     expect(getCaps().capForHolder("alice", doc)).toBeDefined();
     expect(await documentsGivenTo("alice")).toContain(doc);
   });
+
+});
+
+/**
+ * The list the observation works from, asked directly.
+ *
+ * It is built from two independent registers — the account record, which names the user's own
+ * two store inboxes, and the User branch, which names one per document it opened an inbox on
+ * — and the two fail independently. What a caller may do with a half-read list depends
+ * entirely on being TOLD it is half-read, so both halves of that answer are pinned here
+ * rather than only through the behaviour above.
+ */
+describe("listing the inboxes when one of the two registers cannot be read", () => {
+  test("comes back as what WAS listed plus the failure — never as a short list", async () => {
+    await signIn("alice");
+    // A document inbox: a record on the User branch of the private store, which is the
+    // register the broker is about to stop answering for.
+    const note = await storeRegistry.createEntityDoc("public");
+    await storeRegistry.openDocumentInbox(note);
+    await converge();
+    const store = (await resolveAccount("alice"))?.docPrivate;
+    if (store === undefined) throw new Error("the fixture did not give Alice a private store");
+
+    const whole = await enumerateMyInboxes();
+    expect(whole.incomplete).toBeNull();
+    expect(whole.inboxes).toContain(inboxOnTheNote(note));
+
+    fake._failReadsOn.add(store);
+    const partial = await enumerateMyInboxes();
+    fake._failReadsOn.delete(store);
+
+    // Her own two inboxes were in hand before the second register threw. Discarding them
+    // with it is what left an identity connected with ZERO inboxes watched.
+    expect(partial.inboxes).toEqual([
+      await userInbox("alice", "public"),
+      await userInbox("alice", "protected"),
+    ]);
+    // …and the shortfall travels WITH them: an answer that came back short while looking
+    // complete is a failure disguised as an absence, which is the fault this package keeps
+    // closing. The document inbox is missing from the list and that fact is legible.
+    expect(partial.incomplete).not.toBeNull();
+    expect(String(partial.incomplete?.error)).toContain("RepoNotFound");
+    expect(partial.inboxes).not.toContain(inboxOnTheNote(note));
+  });
+
+  test("still REJECTS for the caller that cannot use a partial list", async () => {
+    await signIn("alice");
+    await storeRegistry.openDocumentInbox(await storeRegistry.createEntityDoc("public"));
+    await converge();
+    const store = (await resolveAccount("alice"))?.docPrivate;
+    if (store === undefined) throw new Error("the fixture did not give Alice a private store");
+
+    fake._failReadsOn.add(store);
+    try {
+      // `connect.connectedUser` drains this list, and a queue missing from it is a delivered
+      // share silently never applied. Not knowing which queues exist is the session failing
+      // to establish, and that contract is not what the partial answer above relaxes.
+      await expect(myInboxes()).rejects.toThrow(/RepoNotFound/);
+    } finally {
+      fake._failReadsOn.delete(store);
+    }
+  });
 });

packages/polyfill/test/subscribe.test.ts

@@ -1,6 +1,7 @@
 import { test, expect, mock, afterAll } from "bun:test";
 import {
   docChangeType,
+  resubscribeDocs,
   subscribeDoc,
   subscribeDocReportingSetupFailure,
   subscribeDocs,
@@ -40,10 +41,19 @@ const SESSION: RegistrySession = { sessionId: "sid-1", privateStoreId: "PRIV" };
  * exactly the assumption that cost this package a view that never re-read and an inbox that
  * never notified, and a fake that holds it cannot fail on either.
  */
-function makeFakeNg(failFor: Set<string> = new Set()) {
+function makeFakeNg(failFor: Set<string> = new Set(), hangFor: Set<string> = new Set()) {
   const subs = new Map<string, (r: unknown) => void>();
+  // A call the broker has neither answered nor refused yet, so a LATER call can overtake it
+  // and this one can settle afterwards. Held on an object rather than in a `let` so its
+  // type survives being written from one closure and read from another.
+  const hung: { reject: ((error: unknown) => void) | null } = { reject: null };
   const doc_subscribe = mock(async (nuri: string, _sid: unknown, cb: (r: unknown) => void) => {
     if (failFor.has(nuri)) throw new Error(`RepoNotFound: ${nuri}`);
+    if (hangFor.has(nuri)) {
+      return await new Promise((_resolve, reject) => {
+        hung.reject = reject;
+      });
+    }
     subs.set(nuri, cb); // whoever held this branch is dropped, without a word
     // Initial State push, delivered async (as the real RPC does) — and only while this
     // callback still holds the branch.
@@ -58,11 +68,17 @@ function makeFakeNg(failFor: Set<string> = new Set()) {
     subs.get(nuri)?.({ V0: { Patch: { doc: nuri } } });
   };
   const isSubscribed = (nuri: string): boolean => subs.has(nuri);
-  return { doc_subscribe, push, isSubscribed, _subs: subs };
+  /** The call that was left hanging finally answers — with a refusal. */
+  const rejectHung = (): void => {
+    const reject = hung.reject;
+    hung.reject = null;
+    reject?.(new Error("RepoNotFound: late"));
+  };
+  return { doc_subscribe, push, isSubscribed, rejectHung, _subs: subs };
 }
 
-function inject(failFor?: Set<string>) {
+function inject(failFor?: Set<string>, hangFor?: Set<string>) {
-  const ng = makeFakeNg(failFor);
+  const ng = makeFakeNg(failFor, hangFor);
   configure({ ng: ng as any, useShape: (() => {}) as any });
   // Synchronous fake store → no sync lag; disable the anti-fork retry backoff.
   configureStoreRegistry({ getSession: async () => SESSION });
@@ -321,3 +337,80 @@ test("a caller that asks to be told learns its subscription could not be opened"
   expect(String(failures[0])).toContain("RepoNotFound");
   stop();
 });
+
+/**
+ * Two establishes over ONE fan-out, and the first one answering last.
+ *
+ * `resubscribeDocs` re-opens the channel of a fan-out whose first `doc_subscribe` has not
+ * settled yet — that is the whole point of it, since the session it was opened against is
+ * gone — and it re-opens it on the SAME entry so the listeners are kept. The two calls
+ * therefore race, and the broker is under no obligation to answer them in order.
+ */
+async function hangingThenReopened(): Promise<{
+  ng: ReturnType<typeof makeFakeNg>;
+  failures: unknown[];
+  seen: unknown[];
+  stop: Unsubscribe;
+}> {
+  const hangFor = new Set([A]);
+  const ng = inject(new Set(), hangFor);
+  const failures: unknown[] = [];
+  const seen: unknown[] = [];
+  const stop = subscribeDocReportingSetupFailure(
+    A,
+    (r) => seen.push(r),
+    (error) => failures.push(error),
+  );
+  // Awaited before the broker is allowed to answer: `establish` resolves the session id
+  // first, so the call this has to leave hanging has not been placed yet.
+  await tick();
+  hangFor.delete(A);
+  return { ng, failures, seen, stop };
+}
+
+test("a SUPERSEDED setup rejecting late is not reported as this document failing", async () => {
+  const { ng, failures, seen, stop } = await hangingThenReopened();
+  expect(ng.isSubscribed(A)).toBe(false); // the first call has not answered
+
+  resubscribeDocs(); // the session rotated: a second establish, on the same fan-out
+  await tick();
+  expect(ng.isSubscribed(A)).toBe(true);
+  const before = seen.length;
+  expect(before).toBeGreaterThan(0); // …and it is pushing
+
+  ng.rejectHung(); // …and only now does the first call refuse
+  await tick();
+
+  // Nothing failed: the document is subscribed and pushing. Told otherwise, the caller whose
+  // job depends on this subscription (the inbox observation) releases the entry it holds —
+  // which closes the WORKING channel and reports an inbox that is watched as unwatchable.
+  expect(failures).toEqual([]);
+  expect(ng.isSubscribed(A)).toBe(true);
+  ng.push(A);
+  expect(seen.length).toBeGreaterThan(before);
+  stop();
+});
+
+test("a SUPERSEDED setup rejecting late does not let the next joiner evict the live channel", async () => {
+  const { ng, stop } = await hangingThenReopened();
+  resubscribeDocs();
+  await tick();
+  expect(ng.doc_subscribe).toHaveBeenCalledTimes(2);
+
+  ng.rejectHung();
+  await tick();
+
+  // The second establish still stands, so this joiner must join it. Counting the late
+  // rejection as "nothing is running any more" opens a THIRD `doc_subscribe` — and a second
+  // subscribe on a branch evicts the one before it, so the joiner's own call is what silences
+  // everybody already listening.
+  const late: unknown[] = [];
+  const stopLate = subscribeDoc(A, (r) => late.push(r));
+  await tick();
+  expect(ng.doc_subscribe).toHaveBeenCalledTimes(2);
+  expect(late.length).toBeGreaterThan(0); // replayed the barrier, as any late joiner is
+  ng.push(A);
+  expect(late.length).toBeGreaterThan(1);
+  stopLate();
+  stop();
+});