feat!: une seule reponse a « ce document est-il ouvert dans cette session »

Trois reponses coexistaient et pouvaient se contredire : un ensemble de
souscriptions bootstrap et une carte d'etat de barriere dans `open-repo`, et les
auditeurs du fan-out dans `surface/subscribe`. Les deux premieres survivaient a
la disparition de la troisieme, parce que `resetDocSubscriptions()` - ce que fait
le `configure()` publie - largue ses auditeurs sans rien dire a personne.

Il n'en reste qu'une, l'etat de l'unique souscription reelle du document, exposee
par `docChannel(nuri)`. `open-repo` n'enregistre plus que l'auditeur qu'il a pose
- « est-ce que j'ecoute encore », rien de plus - et derive `getSyncState` a chaque
lecture, si bien qu'aucune reponse ne peut survivre au canal qu'elle decrit.
Disparaissent : `held`, `syncState`, `inFlight`, `settleInFlight` et le compteur
de generation, remplace par l'identite de l'enregistrement.

Les deux echecs prouves deviennent des tests qui echouent sans le changement :
un second `configure()` apres une synchro reussie (`"synced"` au lieu de
`"timed-out"`, zero re-souscription, et `isSuccess` cote application), et un
etablissement encore en cours quand la couche de souscription est demontee - cas
que le canal `onSetupFailed` ne peut pas rattraper, puisqu'il ne rapporte que la
tentative encore attendue.

La ligne qui ne casse pas : un document synchronise qui ne contient rien repond
toujours un succes a zero objet. `1.0.0-dev.10`, les deux non-garanties
nommees sont retirees et la garantie livree porte le test qui l'epingle.

.project/concepts/app-contract/knowledge_what-a-failed-read-answers-upstream.md

@@ -40,6 +40,6 @@ Three rules follow, and all three are load-bearing:
 2. **An empty document is a SUCCESS holding zero objects.** The repair for (1) must never be bought by making a real emptiness into an error; that only moves the lie. An empty document, an empty scope, a document nobody opened an inbox on, a document in a public store that exposes no key - each is an answer, and each stays one.
 3. **The unsynced/empty collision is closed by the barrier, and where the barrier was not crossed the read says so rather than answering.** Crossing it is what makes a zero-row answer mean something (`emulated-verifier/open-repo.ts`, which keeps `synced` and `timed-out` deliberately apart). A reactive read over documents it NAMES consults that distinction and stays PENDING when the barrier was not reached - "I have no authoritative answer" rather than "there is nothing". Turning it into a rejection would be inventing a third outcome the engine does not have, and answering a success would be the collapse this whole leaf is about.
 
-   **What an application can see of this, exactly.** `useShapeQuery` folds it into its own states, and that is the only published channel: a named scope whose barrier was not crossed does not reach `isSuccess` - **within one ordinary session**. Two situations break it, both known defects and both carried as acceptance tests by `T01.m` ("there must be one answer to whether a document is open"): a second `configure(...)`, which tears down the subscription layer without telling the open registry, and a broker refusing a subscription after this package has stopped waiting. In both, a document recorded as open is not, and the read answers an empty success. The REACHABILITY half is unaffected. `inbox.readSyncedForDocument` is the same guarantee on the inbox path. `getSyncState` is INTERNAL and is deliberately not published - this leaf offered it until 2026-09-24, which was a pointer at something no caller can import. It stays internal because it has no counterpart upstream at any level: publishing it would hand an application a polyfill-era symbol to unlearn at migration, on a surface that is busy removing exactly those. The consequence to state plainly rather than paper over: a caller using the anchored `docs.sparqlQuery` directly gets zero rows for an unsynced document and has **no published way to tell that from an empty one** - that is the collapse upstream has too, and it is why the reactive read is the one that carries the distinction.
+   **What an application can see of this, exactly.** `useShapeQuery` folds it into its own states, and that is the only published channel: a named scope whose barrier was not crossed does not reach `isSuccess`. That held only **within one ordinary session** until `1.0.0-dev.10`: a second `configure(...)` tore down the subscription layer without telling the open registry, and a broker refusing a subscription after this package had stopped waiting left the document recorded as open - in both, a document recorded as open was not, and the read answered an empty success. Closed by giving the question ONE answer: openness is the state of the document's one real subscription, read rather than remembered, so no record of it can outlive the channel it describes. The REACHABILITY half was never affected. `inbox.readSyncedForDocument` is the same guarantee on the inbox path. `getSyncState` is INTERNAL and is deliberately not published - this leaf offered it until 2026-09-24, which was a pointer at something no caller can import. It stays internal because it has no counterpart upstream at any level: publishing it would hand an application a polyfill-era symbol to unlearn at migration, on a surface that is busy removing exactly those. The consequence to state plainly rather than paper over: a caller using the anchored `docs.sparqlQuery` directly gets zero rows for an unsynced document and has **no published way to tell that from an empty one** - that is the collapse upstream has too, and it is why the reactive read is the one that carries the distinction.
 
 Related: `knowledge_what-a-read-scope-is-upstream` (what a read request can SAY, including the `[]` that means the empty set and the `[]` that means no filtering), and `polyfill-surface/contract_polyfill-surface` `## Guarantees` for the caller-facing form of all of this.