refactor(client): open-repo attend le 1er STATE (barrière de sync), pas TabInfo

Avant : `ensureRepoOpen` résolvait son attente sur le 1er push d'abonnement (=
TabInfo, ~1-3ms) — donc AVANT la vraie barrière de sync. Correct par chance sur ce
broker (State suit TabInfo d'~1ms), faux si State tarde.

Maintenant :
- `subscribe.ts` : `docChangeType(resp)` extrait le variant (`State`/`Patch`/
  `TabInfo`/…) sans cast `any` ; `subscribeDoc`/`subscribeDocs` le passent en 2e
  arg NON-cassant (les appelants 0-arg — discovery, inbox — inchangés).
- `ensureRepoOpen` n'agit que sur `type === "State"` → attend la vraie barrière.
- État de sync par-doc explicite : `getSyncState(nuri): "syncing"|"synced"|
  "timed-out"|"unknown"`. Le fallback 8s marque `timed-out`, JAMAIS `synced` — les
  deux ne sont plus confondus (base du futur signal app + du « trop long = signal »).
- Fake ng (sans doc_subscribe) : résolution immédiate préservée (bun test intact).

gate : tsc propre ; bun test 117 ; test:e2e 39 passed (CONTRAT 3 vert,
events=["TabInfo","State"] ; reconnexion cold-read 176ms/10.8s — l'attente du 1er
State se déclenche vite, pas de gonflement par timeout). Pas de régression app (le
rouge du test reconnexion est pré-existant et broker-lenteur, vérifié sur lib vierge).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/client/src/index.ts

@@ -18,8 +18,8 @@ export * as inbox from "./inbox";
 export * as discovery from "./discovery";
 export type { IndexEntry, SubmitOptions } from "./discovery";
 export * as docs from "./docs";
-export { subscribeDoc, subscribeDocs } from "./subscribe";
-export type { DocChange, Unsubscribe } from "./subscribe";
+export { subscribeDoc, subscribeDocs, docChangeType } from "./subscribe";
+export type { DocChange, DocChangeType, Unsubscribe } from "./subscribe";
 export * as readModel from "./read-model";
 export type { UnionSubject } from "./read-model";
 export * as storeRegistry from "./store-registry";

packages/client/src/open-repo.ts

@@ -20,9 +20,13 @@
  *
  * ── How we open ───────────────────────────────────────────────────────────
  * We reuse the existing per-document primitive {@link subscribeDoc} (the typed
- * wrapper over the platform's `doc_subscribe`) — NOT a parallel channel. The
- * subscribe pushes the repo's initial `State` once it is opened/loaded; we await
- * that first push (bounded) and treat it as "the repo is now in the session". The
+ * wrapper over the platform's `doc_subscribe`) — NOT a parallel channel. On
+ * subscribe the platform pushes `TabInfo` FIRST (~1-3ms) and then the initial
+ * `State` (~2-3ms); the FIRST `State` is the sync BARRIER — after it, presence is
+ * guaranteed and absence definitive (pinned empirically by CONTRACT 3 in `e2e/`).
+ * So we await that first `State` specifically (identified via the `type` argument
+ * {@link DocChangeType} `subscribeDoc` now surfaces), NOT the first push of any
+ * kind — resolving on `TabInfo` would return before the real barrier. The
  * subscription is kept ALIVE for the whole session (that is what keeps the repo
  * open) — it is a bootstrap open, distinct from any reactive subscription a caller
  * later establishes for change signals.
@@ -34,8 +38,20 @@
  * the injected session id CHANGES within the same page (an in-page re-login /
  * `session_stop`+`session_start`, whose new verifier has an empty `self.repos`) the
  * registry auto-resets (`syncSession`) so repos are re-opened against the new session
- * rather than wrongly skipped as "already open". No polling: we wait on the
- * initial-state push, with a bounded fallback timeout so a missing push can't hang.
+ * rather than wrongly skipped as "already open". No polling: we wait on the first
+ * `State` push, with a bounded fallback timeout so a missing push can't hang.
+ *
+ * ── Sync state (per-nuri, lib-internal) ───────────────────────────────────
+ * Each nuri carries an explicit sync state, readable via {@link getSyncState}:
+ *   `"syncing"`   — subscribed, no `State` yet (barrier not reached);
+ *   `"synced"`    — first `State` received (barrier reached — the TRUTH signal);
+ *   `"timed-out"` — the bounded fallback fired with NO `State` (open proceeded so
+ *                   the read is never blocked, but this is NOT `"synced"`: a future
+ *                   "ready" signal must not mistake a timeout for a real barrier);
+ *   `"unknown"`   — never requested (or the fake-ng no-op path: no `State` semantics).
+ * This distinction is the point — `"synced"` and `"timed-out"` are kept apart so a
+ * later reactive readiness layer can trust `"synced"` and treat `"timed-out"` as
+ * "opened best-effort, sync unconfirmed".
  *
  * ── Migration ─────────────────────────────────────────────────────────────
  * At the real multi-store migration this becomes "open the user's store repo by
@@ -47,12 +63,24 @@ import { getConfig, getStoreRegistryDeps } from "./polyfill";
 import { subscribeDoc, type Unsubscribe } from "./subscribe";
 import type { Nuri } from "./types";
 
-/** Repos whose bootstrap open has completed (initial state pushed or timed out). */
+/**
+ * The per-nuri bootstrap sync state (lib-internal). See the module header:
+ *   - `"syncing"`   subscribed, first `State` not yet received;
+ *   - `"synced"`    first `State` received — the real sync barrier (CONTRACT 3);
+ *   - `"timed-out"` fallback fired without a `State` — open proceeded, sync UNconfirmed;
+ * `"unknown"` (from {@link getSyncState}) means "never requested / no `State` semantics".
+ */
+export type SyncState = "syncing" | "synced" | "timed-out";
+
+/** Repos whose bootstrap open has completed (first `State` received OR timed out). */
 const opened = new Set<Nuri>();
 /** In-flight opens, so concurrent `ensureRepoOpen(nuri)` share one subscription. */
 const inFlight = new Map<Nuri, Promise<void>>();
 /** Live bootstrap subscriptions, kept for the session (this is what holds repos open). */
 const held = new Map<Nuri, Unsubscribe>();
+/** Explicit per-nuri sync state — the barrier signal, distinct from `opened`.
+ *  `synced` and `timed-out` are NOT merged (see module header). */
+const syncState = new Map<Nuri, SyncState>();
 /** The session id the current `opened`/`held` entries belong to. A change means a
  *  new verifier session (fresh `self.repos`) → the registry must be invalidated. */
 let boundSessionId: string | number | null = null;
@@ -78,9 +106,23 @@ export function resetOpenedRepos(): void {
   opened.clear();
   inFlight.clear();
   held.clear();
+  syncState.clear();
   boundSessionId = null;
 }
 
+/**
+ * The bootstrap sync state of `nuri` (lib-internal accessor; NOT a reactive
+ * app-facing hook — that is a later phase). Returns `"unknown"` if the repo was
+ * never opened via {@link ensureRepoOpen} (or was opened on the fake-ng no-op
+ * path, which has no `State` semantics). Otherwise `"syncing"` (subscribed, no
+ * `State` yet), `"synced"` (first `State` received — the barrier), or
+ * `"timed-out"` (fallback fired without a `State`). `"synced"` and `"timed-out"`
+ * are deliberately distinct — a later readiness signal must not confuse them.
+ */
+export function getSyncState(nuri: Nuri): SyncState | "unknown" {
+  return syncState.get(nuri) ?? "unknown";
+}
+
 /**
  * Invalidate the registry if the active session id changed since it was populated.
  * A new session id means a new verifier with an EMPTY `self.repos`, so entries from
@@ -101,8 +143,9 @@ async function syncSession(): Promise<void> {
 /**
  * Ensure `nuri`'s repo is OPEN in the current session before an anchored read,
  * so the cold-start (fresh session, same persistent wallet) resolves it instead
- * of returning 0 rows. Opens via {@link subscribeDoc} and awaits the initial state
- * push (bounded). Idempotent: a repo already opened (or in flight) is not re-opened.
+ * of returning 0 rows. Opens via {@link subscribeDoc} and awaits the first `State`
+ * push — the sync barrier (bounded fallback marks the nuri `"timed-out"`, not
+ * `"synced"`). Idempotent: a repo already opened (or in flight) is not re-opened.
  *
  * Tolerant by construction: if the injected `ng` exposes no `doc_subscribe` (e.g.
  * the fake `ng` in the unit suite), this is a no-op — the read proceeds unchanged.
@@ -116,29 +159,47 @@ export async function ensureRepoOpen(nuri: Nuri): Promise<void> {
   const pending = inFlight.get(nuri);
   if (pending) return pending;
 
-  // No reactive primitive on the injected ng (fake-ng unit suite): nothing to open.
+  // No reactive primitive on the injected ng (fake-ng unit suite): nothing to open,
+  // no `State` to await → preserve the old immediate-resolve behaviour so `bun test`
+  // does not regress. No sync state is recorded (getSyncState → "unknown"): the fake
+  // path has no barrier semantics, and claiming "synced" here would be a lie.
   const ng = getConfig().ng as { doc_subscribe?: unknown };
   if (typeof ng.doc_subscribe !== "function") {
     opened.add(nuri);
     return;
   }
 
+  // Subscribed, first `State` not yet seen.
+  syncState.set(nuri, "syncing");
+
   const p = (async () => {
     await new Promise<void>((resolve) => {
       let settled = false;
-      const done = (): void => {
+      // Resolve on the first `State` (the sync BARRIER), marking the nuri "synced".
+      const onState = (): void => {
         if (settled) return;
         settled = true;
+        syncState.set(nuri, "synced");
+        resolve();
+      };
+      // Bounded fallback: proceed WITHOUT a `State`, but mark "timed-out" — NOT
+      // "synced". A genuinely-absent doc reads 0 rows anyway (same as before, never
+      // a hang); the distinct state keeps a future "ready" signal from lying.
+      const onTimeout = (): void => {
+        if (settled) return;
+        settled = true;
+        syncState.set(nuri, "timed-out");
         resolve();
       };
       // The bootstrap subscription is kept ALIVE for the session — holding it open
-      // is the whole point; we resolve on the FIRST push (the initial State), which
-      // means the repo is now loaded in the session.
-      const unsub = subscribeDoc(nuri, () => done());
+      // is the whole point. We wait for the FIRST `State` event specifically (the
+      // barrier), NOT any push: the platform pushes `TabInfo` before `State`, and
+      // resolving on `TabInfo` would return before the real sync barrier.
+      const unsub = subscribeDoc(nuri, (_r, type) => {
+        if (type === "State") onState();
+      });
       held.set(nuri, unsub);
-      // Bounded fallback: proceed even if no push arrives (a genuinely-absent doc
-      // reads 0 rows anyway — same as before — never a hang). NO polling.
-      setTimeout(done, OPEN_TIMEOUT_MS);
+      setTimeout(onTimeout, OPEN_TIMEOUT_MS);
     });
     opened.add(nuri);
     inFlight.delete(nuri);

packages/client/src/subscribe.ts

@@ -45,6 +45,35 @@ import type { Nuri } from "./types";
  */
 export type DocChange = unknown;
 
+/**
+ * The discriminant of a {@link DocChange} — the single variant key of the raw
+ * `AppResponse` payload (`{ V0: { State | Patch | TabInfo | … } }`). It is NOT a
+ * closed enum: the platform may push other variants, so this is a bare `string`
+ * (e.g. `"State"`, `"Patch"`, `"TabInfo"`), or `undefined` when the shape can't
+ * be read. Verified against the CONTRACT-3 e2e probe (`e2e/sdk-entry.ts`): the
+ * variant is `Object.keys(resp.V0)[0]`. Exposed so a caller that needs the SYNC
+ * BARRIER (the first `State`, per CONTRACT 3) can distinguish it from the earlier
+ * `TabInfo`/`Patch` pushes — see `open-repo.ts`. Most callers ignore it and use
+ * any push as a plain change signal.
+ */
+export type DocChangeType = string | undefined;
+
+/**
+ * Extract the variant key from a raw {@link DocChange}. Reads `resp.V0` (case-
+ * tolerant to `v0`) and returns its first key — the AppResponse variant name
+ * (`"State"` / `"Patch"` / `"TabInfo"` / …). Returns `undefined` if the payload
+ * is not a recognisable `{ V0: { <Variant>: … } }` object. Inspects the variant
+ * proplerly (no `any`-cast to force it) so a `State` push is identifiable.
+ */
+export function docChangeType(resp: DocChange): DocChangeType {
+  if (!resp || typeof resp !== "object") return undefined;
+  const outer = resp as { V0?: unknown; v0?: unknown };
+  const v0 = outer.V0 ?? outer.v0;
+  if (!v0 || typeof v0 !== "object") return undefined;
+  const keys = Object.keys(v0 as Record<string, unknown>);
+  return keys.length > 0 ? keys[0] : undefined;
+}
+
 /** An unsubscribe function — idempotent (calling it twice is a no-op). */
 export type Unsubscribe = () => void;
 
@@ -63,9 +92,18 @@ async function sessionId(): Promise<string> {
  * cancellation is honoured as soon as the real unsubscribe is available (and no
  * further `onChange` fires after unsubscribe).
  *
+ * `onChange` receives the raw payload AND its variant type ({@link docChangeType},
+ * e.g. `"State"`). The type is a NON-BREAKING second argument: existing callers
+ * that ignore it (the change-signal pattern — `discovery.ts`, `inbox.ts`) are
+ * unaffected; a caller that needs the sync barrier (`open-repo.ts`) reads it to
+ * act only on the first `State`.
+ *
  * Calls the REAL injected `ng.doc_subscribe` directly (never `makeNg`).
  */
-export function subscribeDoc(nuri: Nuri, onChange: (r: DocChange) => void): Unsubscribe {
+export function subscribeDoc(
+  nuri: Nuri,
+  onChange: (r: DocChange, type: DocChangeType) => void,
+): Unsubscribe {
   const { ng } = getConfig();
   let stopped = false;
   let realUnsub: (() => void) | null = null;
@@ -73,7 +111,7 @@ export function subscribeDoc(nuri: Nuri, onChange: (r: DocChange) => void): Unsu
   const cb = (resp: DocChange): void => {
     if (stopped) return;
     try {
-      onChange(resp);
+      onChange(resp, docChangeType(resp));
     } catch (error) {
       console.error("[subscribe] onChange handler threw for", nuri, error);
     }
@@ -123,7 +161,7 @@ export function subscribeDoc(nuri: Nuri, onChange: (r: DocChange) => void): Unsu
  */
 export function subscribeDocs(
   nuris: Nuri[],
-  onChange: (nuri: Nuri, r: DocChange) => void,
+  onChange: (nuri: Nuri, r: DocChange, type: DocChangeType) => void,
 ): Unsubscribe {
   const unique = [...new Set(nuris.filter(Boolean))];
   const unsubs = unique.map((nuri) => {
@@ -131,7 +169,7 @@ export function subscribeDocs(
     // async setup failure (logged, never thrown), so one bad doc cannot abort the
     // construction of the others here.
     try {
-      return subscribeDoc(nuri, (r) => onChange(nuri, r));
+      return subscribeDoc(nuri, (r, type) => onChange(nuri, r, type));
     } catch (error) {
       console.error("[subscribe] subscribeDocs: failed to subscribe", nuri, error);
       return () => {};