ng-eventually/docs/nextgraph-current-state.md

# Current-state NextGraph — what the SDK/broker do and do NOT expose

**Owner:** this library. `@ng-eventually/client` exists because the *current*
NextGraph JS SDK is immature. This file is the authoritative reference on what
today's SDK/broker actually give us — the ground truth every polyfill in this
lib compensates for. Read [`simulation.md`](./simulation.md) for how we emulate
the mature behaviour on top of these limits, and
[`migration-guide.md`](./migration-guide.md) for what changes when they lift.

Verified against `nextgraph-rs` (local clone at `../nextgraph-rs`, sibling of
this repo) and the installed npm packages. Store/permission facts cross-checked
with the official docs ([Documents & Stores](https://docs.nextgraph.org/en/documents/),
[Getting started](https://docs.nextgraph.org/en/getting-started/)).

## Source pointers (`nextgraph-rs`)

Where the ground truth lives, so future re-verification is cheap:

- `sdk/js/lib-wasm/src/lib.rs` — the wasm API actually exposed to JS.
- `engine/net/src/app_protocol.rs` — `AppRequestCommandV0` enum, `NuriV0` formats.
- `engine/verifier/src/request_processor.rs` — the effective `app_request`
  dispatch (the truth on what is actually *processed*).
- `engine/net/src/types.rs` — inbox types (`InboxPost`, `InboxMsg`, `InboxMsgContent`).
- `engine/verifier/src/inbox_processor.rs` — inbox message handling.
- `engine/verifier/src/verifier.rs:2237` — `load_repo_from_read_cap`, the one path that
  brings a repo in FROM a cap (`pub(crate)`, see § *Capability / ReadCap granularity*).
- `engine/verifier/src/verifier.rs:1423` — the `OpenRepo` TODO. It is **not** about
  loading an unheld repo: it sits inside `open_branch_`, past
  `self.repos.get_mut(repo_id).ok_or(RepoNotFound)?` (`:1331`), so the repo is already
  held by the time that line runs. What is missing is the broker-side `OpenRepo`
  request, worked around with a pin.
- `engine/repo/src/types.rs` — `RootBranchV0.store: StoreOverlay` (repo → its store).

## The 5 store types

The **3 default stores** belong to a **user**, not to the wallet. A wallet holds
`sites: HashMap<String, SiteV0>` (`engine/wallet/src/types.rs:456`), and it is `SiteV0`
that carries `public` / `protected` / `private` (`engine/verifier/src/site.rs:31-37`) —
one wallet can hold several, which is exactly why "wallet" is the wrong unit to reason
in (see `docs/readcap-and-nuri-model.md` §4quinquies, *Nomenclature first*). A session exposes the three as
`private_store_id`, `protected_store_id`, `public_store_id` — those are the connected
USER's. Group and Dialog are created on demand.

| Store | Read | Write | Creation |
|---|---|---|---|
| **Private** | Owner only | Owner only | Default |
| **Protected** | Owner + link+permission holders | Owner + permissioned collaborators | Default |
| **Public** | Everyone, no capability | Owner only | Default |
| **Group** | Group members | Group members (collaborative) | On demand |
| **Dialog** | The two users only | The two users only | On demand |

Doc citations (verbatim): Private — *"only you have access to … not possible to
share"*; Protected — *"share … but they will need a special link and permission"*;
Public — *"equivalent to your website … without the need for special permissions"*;
Group — *"each Group is a separate Store … documents inherit the permissions of
the store"*; Dialog — *"hold all the data you exchange with another user (and only
with that other user) … You cannot add more users"*.

## Document = repo (there is no `Document` type)

*"A Repo is the equivalent of an E2EE group for one and only one Document."*
**1 document = 1 repo** (commits + permissions). Identifier: `did:ng:o:<RepoID>`.

There is **no `Document` type** in `nextgraph-rs` (verified 2026-06-29): a
"document" is simply *any repo*. A **store is a special repo** (`is_store=true`,
with `Store`/`Overlay`/`User` branches) — so *a store is a document, but a
document is not necessarily a store*.

**Containment (store → repos) is by REFERENCE, not by a list.** A store does not
hold a `Vec<RepoId>`: it references its repos through an **RDF graph** in its
Overlay/User branch. Conversely each repo names its parent store via
`RootBranchV0.store: StoreOverlay` — **a repo belongs to exactly one store**.

## Capability / ReadCap granularity — the load-bearing fact for this lib

`ReadCap = ObjectRef`. Granularity is at the **repo AND branch** level (each
branch has its own `read_cap`), down to the **block** (`ObjectKey`/ChaCha20 key).
Write is managed at the **document (repo)** level.

**No automatic read inheritance.** Holding a **store's** ReadCap does **not**
grant the repos it contains — **you need each repo's own ReadCap**. The optional
`inherit_perms_users_and_quorum_from_store: Option<ReadCap>` shares only
users/quorum (write/permissions), **not** read-cap possession. (Repos of a
`private_store` inherit implicitly.)

> Consequence for this lib's emulation (see [`simulation.md`](./simulation.md)):
> the read access unit is the repo = each item's `@graph` — a per-document
> filter, never per-store and never per-item. This is exactly what
> `caps.ts` (`CapRegistry`) and `read-filter.ts` model: no store-level
> inheritance, purely per-document caps. In a mono-store layout (all items in one
> repo) the filter is therefore all-or-nothing on that document — which *is* the
> native behaviour, and why fine-grained isolation requires one document per
> entity. Read isolation is cryptographic in the target: with no cap for a repo, a
> union / reactive read returns empty (the repo is never decrypted), while a
> targeted read of an unheld repo returns `RepoNotFound`. There is no
> cap-introspection API, and there is nothing to introspect: reading is key
> possession, so the polyfill asks the only question the model admits —
> `capFor(doc)`, "do I hold it?". Its *implementation* is emulation-only; its shape
> is the target's.

### Store ↔ document confusion (recurring)

The isolation axis is the **document (repo/`@graph`)**, never the **store**: a
store *contains* several documents and does not share their read caps. See the
two-axes warning in [`simulation.md`](./simulation.md): "multi-store" in this
lib's emulation means **multiple DOCUMENTS in one shared store**, not multiple
stores.

## Capability sharing / NURI

Sharing transmits a **NURI** embedding the crypto capability (read and/or write).
No central ACL: holding the NURI *is* the right. *"adding permissions can be done
offline"*; *"removing permissions … requires a SyncSignature"* (synchronous).

## Inbox

**Only two repos have an inbox today: a user's public and protected STORES.** Not
documents, and not the private store. `new_store_default` attaches one solely `if
!private` (`engine/verifier/src/verifier.rs:2994`), and `doc_create` goes through
`new_repo_default`, which leaves `inbox: None` (`engine/repo/src/repo.rs:574`). The only
`AddInboxCap` commits in the whole engine are the two in `engine/verifier/src/site.rs:128,149`
— one for the public store repo, one for the protected one.

**But the engine SUPPORTS an inbox on any repo — "does not" and "cannot" are different
statements.** `inbox: Option<PrivKey>` is a field of EVERY `Repo`
(`engine/repo/src/repo.rs:126`), not of a store structure. `AddInboxCapV0` is keyed by
`repo_id` (`engine/repo/src/types.rs:1973`) — *"Repo the Inbox is opened for"*. And
`update_inbox_cap_v0` applies it via `self.repos.get_mut(repo_id)` with **no `is_store`
check of any kind** (`engine/verifier/src/verifier.rs:1920`). It is generic by
construction, and available at any time: `AddInboxCap` is a User-branch commit
(`engine/repo/src/commit.rs:1043-1050`) whose type documents the late case — *"DEPS to
the previous AddInboxCap commit(s) if it is an update"*.

So a per-document inbox is **not an anticipation**: it is an engine capability that no
code path exercises automatically and that no level-2 or level-3 API exposes. This lib
implements it aligned on the engine's model.

A non-editor can deposit into an inbox without being invited as an editor; the owner
moderates. NURI: `did:ng:d:<inbox_id>`. Content: the `InboxMsgContent` enum (`ContactDetails`,
`DialogRequest`, `Link`, `Patch`, `ServiceRequest`, `ExtRequest`,
`RemoteQuery`, `SocialQuery`…, `engine/net/src/types.rs:4249-4261`). Note what `Link`
is: a **unit variant, carrying nothing** — not a link, not a cap, just a discriminant.
Reading it as "the inbox can deliver a read capability" is the trap this file exists to
prevent; see the *Consequence for this lib* below, which says the same thing from the
other end. Messages are sealed (`crypto_box::seal`) to
the inbox pubkey, so only the owner decrypts. The `from` field is optional, so an
anonymous sender is possible. This is the "identified if known, anonymous
otherwise" behaviour native to the protocol.

The recipient's own verifier unseals each queued message and applies it inline when
it processes its inbox — there is no separate curator or materialization service.

### The inbox is not usable from the JS SDK

- `app_request(request)` is exposed, and `AppRequestCommandV0::InboxPost` +
  `AppRequest::inbox_post()` exist, but the verifier's `request_processor`
  has no `InboxPost` arm (arms actually handled: `OrmStart(Discrete)`,
  `Fetch`, `FileGet`, `OrmUpdate`, `OrmDiscreteUpdate`, `SocialQueryStart`,
  `QrCodeProfile(Import)`, `Header`, `Create`, `FilePut`). Sending an `InboxPost`
  triggers nothing.
- Building an `InboxPost` requires crypto sealing on the Rust side; no wasm
  helper exposes it, and **no `inbox` method exists in `@ng-org/web` at all**.
  *(`inbox_post_link`, named across this repo's docs, is OUR proposed name from
  [`fork-inbox-fallback.md`](./fork-inbox-fallback.md) — grep `nextgraph-rs` and it
  is nowhere. Nothing is announced about the eventual JS surface for inboxes: its
  name and shape are unknown, not merely unimplemented.)*
- Inbox deposit is only triggered internally by `QrCodeProfileImport`
  (`post_to_inbox(new_contact_details)`) and `social_query_start` (contact
  propagation via inbox).

**Consequence:** there is no clean way to "drop a Link" into an arbitrary
document's inbox from the JS SDK today. This lib emulates the inbox instead of
patching the broker — see [`simulation.md`](./simulation.md) (emulated inbox) and
[`fork-inbox-fallback.md`](./fork-inbox-fallback.md) (the Rust-patch path not taken).
A related exposed primitive: `social_query_start` (a federated query via inbox up to
`degree` hops) exists but is limited to contacts — it does not cover an anonymous
notification to a non-connected host.

### Delivering a ReadCap through the inbox — the field exists, the path does NOT — VERIFIED

The `ContactDetails` inbox message carries `read_cap: Option<ReadCap>`, commented
*"optional readcap on the profile, if user wants to share the content of profile"*
(`engine/net/src/types.rs`). Nothing behind that field is implemented:

- **Building it panics.** `InboxPost::new_contact_details(…, with_readcap: bool, …)`
  (`engine/net/src/types.rs`) fills `read_cap` with `unimplemented!()` when
  `with_readcap` is true, and `None` otherwise. Asking for a cap in the message is a
  panic, not a feature.
- **Nobody asks for one.** Its ONLY caller is the `QrCodeProfileImport` path in
  `engine/verifier/src/request_processor.rs`
  (`post_to_inbox(InboxPost::new_contact_details(…))`), which passes `with_readcap =
  false`. No message ever carries a cap.
- **The receiver discards it.** The `InboxMsgContent::ContactDetails(details)` arm of
  `engine/verifier/src/inbox_processor.rs` reads `details.profile`, `details.name` and
  `details.email` to build a `social:contact` document — it **never reads
  `details.read_cap`**. Even a hand-crafted message carrying a cap would be dropped.

**Consequence for this lib:** there is no native channel to HAND a key to somebody. The
inbox transports an identity/profile pointer, not a read capability. Combined with
§ *The inbox is not usable from the JS SDK* (no `InboxPost` arm in the request processor
at all), cap delivery must be emulated end to end: the polyfill's emulated inbox and its
`CapRegistry` are not a shortcut around an existing mechanism, they stand in for a
mechanism that does not exist.

## The query capability — ONE local store, named graphs, union queries

The single fact that makes read-time *listing* possible on the shared wallet, and
the reason the reactive ORM must **not** be used as the listing primitive. Verified
directly in `nextgraph-rs`.

### One oxigraph Store per session; each repo is a NAMED GRAPH

- The verifier keeps **ONE** local oxigraph `Store` per session:
  `graph_dataset: Option<Store>` (`engine/verifier/src/verifier.rs:94`).
- Every synced repo's data is inserted into that one store as a **distinct NAMED
  GRAPH keyed by the repo** — `update_graph` writes each repo's main-branch triples
  under `NuriV0::repo_graph_name(&repo_id, &overlay_id)`
  (`engine/verifier/src/commits/transaction.rs:646-701`, the `ov_graphname` /
  `repo_graph_name` around line 669). So all opened repos coexist as named graphs in
  one dataset — a `GRAPH ?g { ... }` body can span them.

### The NURI target decides scope: one repo vs the LOCAL UNION

`sparql_query`'s scope is resolved from the NURI target by
`resolve_target_for_sparql` (`engine/verifier/src/request_processor.rs:256-285`):

- `Repo(repo_id)` / `PrivateStore` → `Some(repo_graph_name)` = **ONE repo's graph**.
- `UserSite` / `None` → `Ok(None)` = the **UNION of all named graphs**. That `None`
  is passed to oxigraph's `store.query(parsed, default_graph)`
  (`engine/oxigraph/src/oxigraph/store.rs:200`) as the default graph, and
  `sparql_query` first calls `dataset.set_default_graph_as_union()` when the query
  has no explicit dataset (`request_processor.rs:656-675`, the
  `if dataset.has_no_default_dataset()` block). Union = "every named graph currently
  in the store".

### The wasm binding defaults the target to UserSite when no `nuri` is passed

The binding (`sdk/js/lib-wasm/src/lib.rs` — both the nodejs variant at ~`350-405`
and the web variant at ~`553-610`) reads the target from the `nuri` arg: a string
`nuri` is parsed; an **absent** `nuri` falls back to
`NuriV0::new_entire_user_site()` = `UserSite`
(`engine/net/src/app_protocol.rs:488-490`). Therefore:

> **`sparql_query(sid, query, base, /*anchor*/ undefined)` queries the LOCAL UNION
> across all synced/opened graphs; with a string anchor it is restricted to that one
> repo.** A `GRAPH ?g { ... }` body then spans/attributes across the local graphs.

### A repo is only queryable once OPENED/synced into the store

A repo's triples enter `graph_dataset` (hence the union) only after the repo is
opened/synced into `self.repos` **and** its commits applied via `update_graph`.

**VERIFIED (T03.k) — there is NO JS primitive to sync an *unknown* repo.** Every
JS entry point that could "open" a repo — `sparql_query` anchored,
`doc_subscribe` (`Fetch::Subscribe`), `orm_start_graph` — resolves its target via
`resolve_target`/`resolve_target_for_sparql`, which does
`self.repos.get(repo_id).ok_or(RepoNotFound)` (`request_processor.rs:155/163/264/269`).
None of them PULLS a repo that is absent from `self.repos`; they only touch a repo
already there. The primitive that actually loads a repo from its ReadCap,
`Verifier::load_repo_from_read_cap` (`verifier.rs:2237`), is **`pub(crate)` —
unexposed to JS**; it is only reached internally (bootstrap, inbox processing). So
from JS today a repo becomes queryable ONLY by being `doc_create`d in this session
(own docs) or synced by an internal path — never on demand by NURI+ReadCap.

**Consequence for this lib's mono-wallet polyfill:** every account's documents are
`doc_create`d in the one shared wallet within the same session, so they are all
already in `self.repos`. `read-model.ts` reads the bounded, by-need set of docs
with one anchored `sparql_query` per doc (`SELECT ?s ?p ?o WHERE { ?s ?p ?o }`,
anchor = the doc NURI): the anchor resolves that same-session repo directly (no
separate open needed) and restricts the query to its graph, so it is O(1) per doc,
independent of the store's size. An absent repo throws `RepoNotFound` on its own
read and is skipped, never aborting the batch.

The read path avoids an anchorless union-scan. An anchorless
`SELECT … WHERE { GRAPH ?g { ?s ?p ?o } }` spans every named graph in the store —
O(wallet size). On a shared wallet that accumulates docs across runs that cost grows
with the whole wallet, which is why the read path is per-doc anchored: the anchored
read makes a non-empty wallet irrelevant. At the real multi-store
migration this is unchanged (the anchored read is native); only bringing a repo into
the session changes: opening a real per-user store repo by cap becomes a native
broker sync, through `load_repo_from_read_cap` (`verifier.rs:2237`) — not through the
`OpenRepo` TODO at `:1423`, which concerns a repo already held. Opening still requires the
repo's NURI + ReadCap — there is no store-level read inheritance (see
§ Capability / ReadCap granularity).

### Findable-without-lookup vs subscribable (first-`State` barrier) — DISJOINT

Two properties a fresh session might want from a document, and **no single document
has both**:

- **Findable without a lookup.** The ONLY NURI a fresh session can NAME with nothing
  but the session in hand is the store-root, `did:ng:${privateStoreId}` (from
  `session.private_store_id`). Any per-document repo is `did:ng:o:<RepoID>` with a
  **random** RepoID minted by `doc_create` — **not derivable**, so it must be looked
  up somewhere first.
- **Subscribable with a sync BARRIER.** `doc_subscribe(nuri)` delivers `TabInfo` then
  an initial **`State`** (`verifier.rs:470`/`:476`); that first `State` is the sync
  barrier — **after it, presence is guaranteed and absence is definitive** (pinned
  empirically by CONTRACT 3 in `packages/client/e2e/`). But this barrier exists only
  for a repo `doc_subscribe` can open, i.e. a `did:ng:o:<RepoID>` repo. A **store-root
  has no first-`State` barrier**: an anchored read on it can return 0 rows during
  sync-lag with no signal distinguishing "still syncing" from "genuinely empty".

> **`doc_fetch_repo_subscribe` / `doc_fetch_private_subscribe` are NOT alternatives to
> `doc_subscribe`** — checked 2026-08-03, because they look like ready-made
> "open a repo" calls and they are not. Neither performs any I/O: each **builds an
> `AppRequest` and returns it serialized** (`sdk/js/lib-wasm/src/lib.rs:1890`, `:1900`),
> with no `session_id` and no callback. `doc_subscribe` builds the *same* request
> (`AppRequest::doc_fetch_repo_subscribe`, `engine/net/src/app_protocol.rs:930` →
> `Fetch(Subscribe)`), then adds the session id and runs it through
> `app_request_stream_` (`lib.rs:1921-1923`). They exist for a caller that wants to
> construct the request and dispatch it itself. So `ensureRepoOpen`'s
> `doc_subscribe` + wait-for-first-`State` is not duplicating an available call — using
> them instead would mean re-implementing what `doc_subscribe` already does. The
> difference in `doc_fetch_private_subscribe` is only its target
> (`NuriV0::new_private_store_target()`, the private store-root), which changes nothing
> about the barrier: a store-root still has none.

These two are **mutually exclusive**: the guessable target (store-root) is not
barrier-authoritative, and the barrier-authoritative target (`o:` repo) is not
guessable. **Consequence:** you cannot build a lookup table that is BOTH reachable
cold (findable) AND authoritative on a cold read (barrier). A cold "0 rows" read of a
store-root graph is therefore fundamentally ambiguous — which is the trap the shim's
account map fell into (see next section).

### The pointer → doc-shim indirection (how the polyfill shim resolves accounts)

`store-registry.ts` keeps a map `identifier → {docPublic, docProtected, docPrivate}`
(the "shim", the account→document trust root). It must be reachable by a fresh
reconnecting session (findable) AND authoritative on a cold read (so a fresh page
does not mistake sync-lag for "account absent" and PROVISION a fork). Since no single
document is both (previous section), the shim uses an **indirection**:

1. **doc-shim** — a `doc_create`d graph document (`did:ng:o:...`, hence a first-`State`
   barrier). **All `AccountRecord`s live inside it.** Because it is subscribable, an
   anchored read behind its `ensureRepoOpen` barrier is **authoritative**: a cold 0
   means the account is genuinely absent.
2. **pointer** — a single well-known, **write-once** triple in the store-root graph,
   `<urn:ng-eventually:shim:root> <urn:ng-eventually:shim:shimDoc> <docShimNuri>`.
   The store-root is findable-without-lookup, so a fresh session can always read it;
   the pointer being the OLDEST, write-once triple in that graph, it is near-always
   already synced on a cold read.

**Resolution** (`resolveShimDoc`): read the pointer from the store-root → open the
named doc-shim through its barrier (`ensureRepoOpen`) → read the account
AUTHORITATIVELY. First login (no pointer): `doc_create` the doc-shim, publish the
pointer, done. A **pointer fork** (two devices each writing a pointer before either
synced) is reconciled to the lexicographically-smallest doc-shim NURI
(content-addressed, so every device converges on the same doc-shim).

**The account-level retry is GONE.** Before this indirection the shim lived directly
in the store-root graph, so an account read had no barrier and a cold 0 was ambiguous;
the lib compensated with a **bounded account-level retry** (`provisionRetry` /
`resolveAccountReliably`) that re-read the account several times before concluding
"new". Moving the records behind the doc-shim barrier makes the account read
authoritative on the FIRST read, so **that retry was removed** — a barrier is
deterministic where a retry only guessed. The only residual bounded guard is a small
re-read of the **pointer** itself (`pointerGuard`, one write-once triple): it can
NEVER re-provision or fork an account — at worst it takes a couple extra reads to see
a pointer that is still landing.

**No legacy migration.** A wallet written under the OLD scheme (accounts directly in
the store-root graph, no pointer) is NOT recovered: opening it under the current scheme
simply provisions a fresh doc-shim, and the pre-indirection store-root records are
ignored. This is deliberate — the only such wallets are dev data — so the resolution
path carries no legacy-migration step; it always reads the account authoritatively from
the doc-shim.

### The union is read-only — writes must target one document

`resolve_target_for_sparql(update=true)` returns `InvalidTarget` for `UserSite` /
`None` (`request_processor.rs:275-282`). So `sparql_update` cannot write "to the
union": every write must name one document's `@graph` — exactly what the
polyfill's `docs.sparqlUpdate` already does.

### No reactive SPARQL — `sparql_query` is one-shot

`sparql_query` is non-streamed: it computes a `QueryResults` and returns once
(`lib-wasm/src/lib.rs:352-405` / `553-610`). There is no "subscribe to a union
query". The only reactive primitives are the streamed ones: `orm_start_graph`,
`orm_start_discrete`, `doc_subscribe`, `app_request_stream`.

### The ORM fan-out hang — verified root cause

The reactive ORM is structurally unfit for a fan-out of per-entity / not-yet-synced
graphs, and this is *why* subscribing such a fan-out hangs:

- `OrmStartGraph` first loops over every graph in the requested scope and calls
  `open_for_target(&nuri.target, /*publisher*/ true)` on each
  (`request_processor.rs:53-66`), and `orm/graph/initialize.rs` does the same
  fan-out again for the graphs the ORM discovers (~`125-128`).
- `open_for_target` → `resolve_target` → `self.repos.get(repo_id).ok_or(RepoNotFound)`
  (`request_processor.rs:286-294` calling `resolve_target` at `:147`, the
  `RepoNotFound` at `:155/:163`).
- A freshly-created per-entity doc, or any not-yet-synced other-account doc,
  is absent from `self.repos`, so `RepoNotFound` propagates through the `?` and
  aborts the whole `orm_start_graph`. The subscription never emits its initial, so
  the ORM `readyPromise` never resolves and the subscription hangs when a fan-out of
  per-entity graphs is passed in.

**Consequence:** passing per-entity / unsynced graphs to the reactive ORM is broken.
Listing must go through a one-shot union `sparql_query` instead — see
[`read-model.md`](./read-model.md).

## JS SDK limits (`@ng-org/web`)

`@ng-org/web` (verified `0.1.2-alpha.13` = `upstream/main` at 2026-05-21, the
installed version) **does NOT expose**: Group/Dialog store creation; capability
sharing (a NURI with rights); permission manipulation; inbox deposit/read.

The JS methods this lib USES: `doc_create`, `doc_subscribe`, `sparql_query`,
`sparql_update`, `orm_start_graph`, `orm_start_discrete`, `graph_orm_update`,
`discrete_orm_update`, `file_get`, `app_request_stream`. That is a working subset,
**not** the surface: `NGModule` exports **77** (`@ng-org/web@0.1.2-alpha.13`,
`dist/index.d.ts:140-268`), including `app_request`, `session_stop`,
`disconnections_subscribe`, `social_query_start`, `upload_start`/`upload_chunk`/
`upload_done`, and the whole `wallet_*` family. Read "not in the list above" as "we do
not call it", never as "it does not exist" — several sections of this very file discuss
methods absent from that subset. The docs announce *"An API will be provided for
permission manipulation"* (no date).

## Integration & deployment model

NextGraph is consumed via an **iframe proxy** (`@ng-org/web`): the third-party
app contains no engine, it delegates to a hosted ng-app (default `nextgraph.net`)
that runs the engine in an iframe.

### The JS packages

- **`@ng-org/web`** — **published**. Lightweight postMessage proxy (no wasm
  embedded). **The** third-party integration path; `@ng-org/orm` and every
  example depend on it. This lib wraps it.
- **`@ng-org/api-web`** — **private** (unpublished). Full in-browser engine
  (loads `@ng-org/lib-wasm` in a Web Worker). Consumed only by `app/nextgraph`
  (the ng-app frontend) — **not** a third-party integration target.
- **`@ng-org/lib-wasm`** — the compiled wasm engine (contains the verifier).
  Source `sdk/js/lib-wasm/`.
- **`nextgraph`** (npm) — the NodeJS API (`pkg-node` build).
- **`@ng-org/orm`** — reactive ORM (`useShape`…), built on `@ng-org/web`.

### Where the verifier runs

In the standard web model, the verifier runs **in the iframe**: `app/nextgraph`
loads `api-web` → `lib-wasm` in a Web Worker, browser-side. The broker (`ngd`)
only does **transport and storage**.

**Consequence:** changing verifier logic (`request_processor`,
`inbox_processor`) means rebuilding the **ng-app**, not the broker.

### iframe model & build-time retargeting

`@ng-org/web` redirects to the hosted ng-app, which reloads the third-party app
in an iframe after auth, then relays over `postMessage`. **Retargetable at build
time** (`sdk/js/web/src/index.ts`, `import.meta.env`):

| Variable | Target |
|---|---|
| `NG_REDIR_SERVER` | default `nextgraph.net` |
| `NG_DEV3` | `127.0.0.1:3033` |
| `NG_DEV` | `localhost:14402`/`14404` |
| `NG_DEV_LOCAL_BROKER` | `localhost:1421` |

**No runtime override** — `init()` takes no broker URL. To point at a
self-hosted ng-app: **rebuild `@ng-org/web`** (pure TS, no wasm → trivial build).

### Proxy ↔ iframe ↔ worker plumbing (generic)

The call path is **entirely generic** (no allowlist): `@ng-org/web` is a JS
`Proxy` relaying *any* method name over `postMessage`; `app/nextgraph` dispatches
via `Reflect.apply(ng[method], …)`. So a new wasm function in simple
request/response form is *reachable* without touching the JS — but that's an
untyped **hack** (quick test, not a plan). The **streamed** case needs an entry
on both sides (`E` in `@ng-org/web` + `streamed_api` in api-web; current streamed
methods: `doc_subscribe`, `orm_start_graph`, `orm_start_discrete`, `file_get`,
`app_request_stream`).

> This is exactly why `docs.ts` in this lib calls the **real injected `ng`**
> directly and never layers our own `Proxy` on top of `@ng-org/web`'s
> iframe-RPC proxy — see the `DataCloneError` double-proxy constraint in
> [`simulation.md`](./simulation.md).

### The broker (ngd)

- Already supports the inbox natively (`inbox_post`, `inbox_register`,
  `inbox_pop_for_user` in `engine/net/src/server_broker.rs`) — a standard `ngd`
  would route the inbox, **no broker patch needed**. The gap is in the
  verifier/SDK layer, not the broker.
- **WebSocket** daemon (`async-tungstenite`), **stateful**: RocksDB under
  `--base-path`, persisted PeerId (critical volume).
- CLI: `--local PORT`, `--domain DOMAIN:PORT,LOCAL_PORT` (behind a TLS-terminated
  reverse proxy — Traefik/Coolify).
- **Serves no static assets**: the ng-app frontend is a separate static deploy
  (`pnpm webfilebuild`). First boot is **interactive** (admin-wallet invitation
  link). Official Dockerfiles are **broken**.

## Apps & services: shared app data goes through a hardcoded app store (section rewritten 2026-08-03)

NextGraph's app/service execution model, and the answer to "can an application hold data common to all its users".

> **Provenance — two layers, do not mix them.** What the **engine** contains is verified below and is vocabulary only. What the **model will be** was stated by the NextGraph developer on 2026-08-03 and is **not implemented**: treat it as the target's declared direction, not as something the clone can confirm. Per [`../README.md`](../README.md)'s design principle, never infer the target's shape from the source's current state — an absent implementation says nothing about the intended one. The previous version of this section drew exactly that inference and concluded the opposite of what the developer states; it has been replaced.

**What the engine actually has — types, no behaviour (verified 2026-08-03):**

- `AppManifestV0` (`engine/wallet/src/permissions.rs:113`) carries `nuri`, `origin` (webapps), `singleton: bool`, `access_requests`, `installs` (Viewer / Editor / ReadService / WriteService / Model, keyed by PrimaryClass), `dependencies`, and presentation fields.
- The JS surface exists: `init(callback, singleton, access_requests)` (`sdk/js/web/src/index.ts:51`) relays `singleton` to the wallet origin by `postMessage`. Every example passes `true`.
- **Nothing consumes it.** The `permissions` module is declared by `engine/wallet/src/lib.rs:19` and imported by no other crate; `AppManifest` is constructed nowhere; no code reads `singleton`; the surrounding `AccessRequest` / `AccessGrant` machinery is in the same state. There is no app runtime, no app store, no global-document type.
- The field's doc comment reads `/// cannot create Documents?` — with the question mark, in the source. It is an open design note, and the developer's statement below settles it the other way. Do not treat it as the semantics.
- **A second, published gloss of the same flag disagrees with that doc comment, and it is the one that matches the developer's statement.** `sdk/js/web/README.md:90,108` annotates the argument as *"will your app create many docs in the system, or should it be launched as a unique instance"* — i.e. `singleton` is about **instance multiplicity**, not about being forbidden to create documents. That is consistent with "a singleton app can also manage ordinary per-user documents" below, and it is the reading to carry. Both README examples pass `true`.
- Unrelated homonyms, so a grep does not mislead: singleton *commits* (`engine/repo/`), the broker singleton (`engine/net/src/broker.rs`), Oxigraph's `empty_singleton` (SPARQL optimiser).

**The declared model (NextGraph developer, 2026-08-03 — not implemented):**

- A singleton app can **also** manage ordinary per-user documents, i.e. cover what a non-singleton app does. When both modes are needed, declaring one app as singleton is enough — there is no need for two apps.
- Centralized data for an application takes the form of a **document, or a store, shared by all its users and hardcoded in the app**.
- The **app's developer holds the write rights** on the app's documents and stores, and can **delegate** them.
- Delegation is **never to all users**. User contributions reach app-owned data **through an inbox** — this is NextGraph's general model, in which nothing is freely writable by everyone.

**Reading of the last point, since it decides the shape of any index:** an app-owned index is not a place users write to. It is a document they can read (its NURI being hardcoded) and **deposit into**, with an authority derived from the developer materializing the deposits — the same deposit-then-materialize shape the inbox already imposes elsewhere, moved up to the app level.

**Open questions to put to the developer before designing on this:**

- What exactly is hardcoded — the store's or document's NURI, and does that carry the read capability?
- How is write delegation transmitted, and is it revocable?
- Who processes the app store's inbox: an instance running with the developer's rights, a service, something else? A deposit nobody materializes is not an index.

**Bearing on [`decisions/discovery-model.md`](decisions/discovery-model.md):** that ADR's superseding block leans in part on the singleton-app path being "not implemented, uncertain". The path is still not implemented, but it is no longer uncertain in direction — the developer names it as *the* way to hold data common to all users. That does not reinstate discovery: the "you cannot discover, you can only follow links" verdict rests on its own footing (the PO, 2026-07-30). It does mean the *singleton-app* half of that reasoning must be re-put rather than cited as closed.

## Third-party wallet auto-import constraint

Verified empirically (2026-06-17): with the **hosted** broker (`nextgraph.net`),
a third-party web app **cannot** provision/import a wallet programmatically. A
wallet must **pre-exist** in the browser before the auth redirect can succeed.

Mechanism (from `@ng-org/web`'s `ngweb.js` dist):

- **`init()` top-level REDIRECTS**: when `window.self === window.top` it does
  `window.location.href = https://nextgraph.net/redir/#/?o=<url>`. The app's code
  stops running.
- **Every `ng.*` method is relayed** by `parent.postMessage` to `nextgraph.net`,
  and the handler **throws `"you must call init() first"` until a session is
  established** (internal `d !== false` guard). This includes
  `wallet_import_from_code`, `add_in_memory_wallet`, `session_in_memory_start`.
- The third-party app runs **inside the iframe only AFTER** the broker has opened
  a wallet and established the session. There is **no window** where our code runs
  *before* the broker's wallet gate → **nothing to hook an auto-import onto**.

Of the wallet-import methods offered on `nextgraph.eu`, only the **wallet FILE**
(`.ngw`) is a static, reusable export; TextCode/QR are temporary device↔device
transfers (5 min, both devices online, single use) — unusable to embed. The only
real way to eliminate the cross-origin round-trip is to self-host/fork the ng-app
(see [`fork-inbox-fallback.md`](./fork-inbox-fallback.md)).

## Login is not programmable

NextGraph login is a web redirect to the broker page (`nextgraph.net`). There
is no way to open a wallet silently — at least one broker-redirect pass per device
is required. Session persistence: the wallet is remembered iframe-side
(`localStorage` long-term + `sessionStorage` for the active session); on reload,
`init()` recovers the session without re-triggering the redirect while the
broker session exists (`sdk/js/web/src/index.ts`, `sdk/js/api-web/main.ts`). A
full browser restart (losing `sessionStorage`) can re-trigger the gate. A real
logout is exposed (`ng.session_stop()`, `ng.user_disconnect()`,
`ng.wallet_close()` in `sdk/js/lib-wasm/src/lib.rs`) but forces a new
redirect afterwards. This lib's identity store sidesteps all of it — the identity
id is set at wallet-import time and relayed to the lib, without a separate login;
see the identity store in [`simulation.md`](./simulation.md).

## Authorship, existence, outer overlay, `Ext` (section added 2026-07-27)

Four capability facts about the current core, verified in `nextgraph-rs`. They bear on
what can be BUILT on top (can we deliver a key? can we tell whether a document exists?
can we attribute a write?) — they are not a security assessment. Each carries its
epistemic status; do not upgrade an INFERRED item without new evidence.

### Author-signature verification is never called at runtime — VERIFIED

`Commit::verify` (`engine/repo/src/commit.rs`) chains `verify_sig` → `verify_perm` →
`verify_full_object_refs_of_branch_at_commit`. Its only callers in the whole tree are
inside `#[cfg(test)] mod test` blocks (`engine/repo/src/commit.rs`,
`engine/repo/src/branch.rs`); `verify_sig` and `verify_perm` have no other caller. The
verifier's commit path calls a **different** `verify`:
`CommitBodyV0::<Body>::verify(commit, self, branch_id, repo_id, store)` in
`engine/verifier/src/verifier.rs` — the `CommitVerifier` trait, which APPLIES a body
(mutating verifier state); it is not a signature check.

Even if it were called it could not succeed. `verify_sig` resolves the author through
`Repo::member_pubkey` → `Repo.members`, and every `Repo` the verifier builds at runtime
sets `members: HashMap::new()` — `engine/verifier/src/user_storage/repo.rs` (with a
literal `//TODO: members`) and `engine/verifier/src/commits/mod.rs`. Only
`Repo::new_with_member` ever populates a member, and it is called only from tests. An
empty table makes `member_pubkey` return `NotFound` →
`CommitVerifyError::PermissionDenied`.

Reading authorship at all presupposes the read cap (VERIFIED): the author field is not a
UserId but `CommitContent::author_digest(user, overlay)`, a BLAKE3 keyed hash, and the
commit content sits in blocks ChaCha20-encrypted under `Object::convergence_key(store)`
(`engine/repo/src/object.rs`), whose key material is the store id **plus the
store-overlay-branch ReadCapSecret**. No read cap → the author field is not even
visible. *Nuance, VERIFIED:* the digest's own hashing key derives from
`overlay_id_for_read_purpose`, which for Public/Protected/Private/Group stores is
`OverlayId::outer(store_id)` — public. What is secret is the commit content, not the
hash key.

**Consequence for this lib:** "who wrote this triple" is unanswerable today — neither
cryptographically (nothing verifies) nor by identity (the digest is opaque without a
member table). Any authorship or provenance the polyfill needs must be carried in the
DATA it writes and re-read from there; an "authored by X" claim in the emulation has no
core check behind it.

### No existence probe at SDK level — addressing presupposes the cap — VERIFIED

`AppRequestCommandV0` (`engine/net/src/app_protocol.rs`) contains no existence command:
`Fetch`, `Pin`, `UnPin`, `Delete`, `Create`, `FileGet`, `FilePut`, `Header`, `InboxPost`,
`SocialQueryStart`, `SocialQueryCancel`, `QrCodeProfile`, `QrCodeProfileImport`,
`OrmStartGraph`, `OrmStartDiscrete`, `OrmGraphUpdate`, `OrmDiscreteUpdate`, `OrmStop`.
Nothing answers *"does document D exist?"*.

The single probe in the tree is internal and cannot answer it either:
`Verifier::has_blocks` (`engine/verifier/src/verifier.rs`) sends
`BlocksExist { blocks, overlay }`. It is `pub(crate)` (never reaches JS); it takes
**`BlockId`s** — content addresses you only hold if you already read the object; it takes
a **`&Repo` already loaded**; and it targets
`repo.store.overlay_for_read_on_client_protocol()` = the **inner** overlay
(`Store::inner_overlay` → `overlay_id_for_write_purpose(store_overlay_branch_readcap.key)`,
`engine/repo/src/store.rs`), derived from the read-cap secret.

**Consequence for this lib:** you cannot prove — nor disprove — the existence of a
document whose key you do not hold. **Addressing presupposes the cap.** Every "is it
there?" question therefore collapses into "can I read it?", which is why absence is only
ever established behind a sync barrier (see § *Findable-without-lookup vs subscribable*)
and never by probing.

### `expose_outer` is hard-coded to `false` — VERIFIED

Both constructors of `PinRepo` — `PinRepo::for_branch` and `PinRepo::from_repo`
(`engine/net/src/actors/client/pin_repo.rs`) — set `expose_outer: false`, and they are
the only two `PinRepoV0` constructions in the tree. No parameter carries the flag up:
`expose_outer` appears nowhere under `sdk/`. The broker side is fully wired
(`RepoInfo.expose_outer: HashSet<UserId>` in `engine/broker/src/server_broker.rs`, the
`if expose_outer` branch in `rocksdb_server_storage.rs`, the outer-overlay registration
in `server_storage/core/overlay.rs`), and the `PinRepo` responder even validates the flag
(refusing `expose_outer` from a peer that publishes no topic) — but no client ever sets
it.

**Consequence for this lib:** a store's **outer** overlay is never registered broker-side,
so there is no anonymous / capability-free read surface to build on. Everything is reached
through the inner overlay, i.e. through a read cap — the same cap-first addressing as
above. The "public store readable by everyone without permission" promise in the official
docs has no client-side switch today.

### The `Ext` protocol serves blocks with no control — VERIFIED

The `ExtObjectGetV0` responder (`engine/net/src/actors/ext/get.rs`) builds
`Store::new_from_overlay_id(&req.overlay, …)` from the OverlayId the **requester
declares**, then returns `Object::load_without_header(obj_id, None, &store)` blocks for
each requested id. No authentication, no verification that the requester belongs to that
overlay. The guards that were planned exist but are dead:

- `Authorization::ExtMessage` is matched in `Broker::authorize`
  (`engine/net/src/broker.rs`) and returns `AccessDenied` — but **no caller ever passes
  it**; the only `authorize` call sites pass `Discover`, `Admin` or `Client`. The
  server-side `StartProtocol::Ext` arm in `engine/net/src/connection.rs` goes straight to
  `StepReply::Responder`, never through `authorize`.
- the config flag whose comment reads *"are ExtRequest allowed on the server? this
  requires the core to be ON."* — `allow_read` in `engine/net/src/types.rs` — is declared
  and defaulted to `false`, and **read nowhere**.
- `ExtRequestContentV0::get_actor` handles `WalletGetExport` and `ExtObjectGet` and falls
  through to `_ => unimplemented!()` for `ExtTopicSyncReq` — a **panic reachable from an
  anonymous peer**. (The commented-out `// Self::ExtTopicSyncReq(a) => a.get_actor(),` on
  that arm and the `// TODO inbox requests` in the enum are *direction hints*, labelled as
  such — not current behaviour.)

**Consequence for this lib:** `Ext` is not a usable read path in either direction. Blocks
come back **encrypted**, and naming them requires ObjectIds you only have once you can
already read — so it grants no capability we could build on, and confirms the shape of
everything above: confidentiality lives entirely in the keys, and holding no key means
holding no partial access, just none.

## Known open issues (section added 2026-07-18)

Live limitations observed against the current core/SDK, each with its epistemic
status. **None is treated.** The status labels below are load-bearing — do not
upgrade an OPEN / UNDETERMINED / HYPOTHESIS item to "confirmed" or "fixed"
without new evidence.

### Write loss on socket death (`SerializationError`) — symptom VERIFIED, mechanism UNSETTLED, OPEN / untreated

A write made just before an idle period / spontaneous socket death
(`SOCKET IS CLOSED Some(Left(SerializationError))`) can be **silently lost**:
the entity is absent on reconnection while the account survives. Reconnection is
an unimplemented `// TODO` stub in the core (`broker.rs`, ≈ `1051-1076`);
`disconnections_subscribe` DOES fire on the failure but nothing — neither this
polyfill nor the consumer app — consumes it; and there is **no
write-durability-confirmation API** a caller could `await`. Full post-mortem
(logs, causal chain, correction leads, none arbitrated):
[`incidents/2026-07-14-write-loss-on-disconnect.md`](./incidents/2026-07-14-write-loss-on-disconnect.md).

### Cold-start read does not rehydrate the owner's own scope from the broker — symptom VERIFIED, root cause UNDETERMINED, OPEN / untreated

Decisive test (2026-07-14): a genuinely no-local cold reader — fresh
non-persistent browser context, SAME wallet + account — reads **0** of the
owner's own scope from the broker. The previously "passing" reconnect test was
FALSE-GREEN: it read the owner's repos from the persistent profile's LOCAL
IndexedDB, so it never proved broker durability. It is UNDETERMINED whether
**(i)** the write never durably reached the broker, or **(ii)** the write IS on
the broker but a fresh session cannot re-open the owner's own scope docs (a
cold-open / rehydration limitation) — both collapse to the same 0-read in this
setup. Next step (NOT done): disambiguate (i) vs (ii) with an independent warm /
second-identity read of the same doc. The same (i)/(ii) reserve is carried in
[`incidents/2026-07-14-write-loss-on-disconnect.md`](./incidents/2026-07-14-write-loss-on-disconnect.md)
(§ *Portée & non-reproduit*), whose Firefox case leans (i) — this cold-reader
signature is distinct (no socket death) and does not settle it.

### Reactive subscription may not echo the writer's OWN local commit — HYPOTHESIS (high-confidence), confirmation in progress (2026-07-18), NOT confirmed, NOT fixed

When a client does a local `sparqlUpdate` on a doc it is itself subscribed to
(`subscribeDoc`/`doc_subscribe`), the subscription callback appears NOT to fire
for its own local commit in the same session, so the polyfill's reactive re-read
chain never runs and consumers keep a stale value until the next connection
delivers a fresh initial `State`. REMOTE commits DO push correctly (verified:
cross-browser reactive update works). Verdict pending a live instrumented run.
Full write-up (suspect link, instrumentation, planned polyfill-side fix):
[`../packages/client/docs/sdk-reference.md`](../packages/client/docs/sdk-reference.md)
§ *Current emulation status*.

### Cold-start anchored read returns 0 rows instead of an error — symptom VERIFIED, mechanism INFERRED, healed polyfill-side

On a FRESH session over the SAME persistent wallet (reconnect, new page, re-login), an
anchored `sparql_query` against a document written in an earlier session comes back with
**0 rows and no error** — persisted documents read as empty. Observed on every anchored
reader of the polyfill and healed identically in each (`ensureRepoOpen` before the read,
`packages/client/src/open-repo.ts`): the user's own documents,
the user's store (`store-registry.ts` `readUserStore`), the by-need doc batch
(`read-model.ts` `readUnion`), and the store-root pointer read (`store-registry.ts`
`resolvePointer`). The heal is `doc_subscribe(nuri)` → await the first `State` (the sync
barrier) → THEN the anchored read, and it is verified to return the data.

The circularity that made it self-inflicted (VERIFIED by the fix working): `doc_subscribe`
WOULD open the repo, but the reactive layer only subscribes AFTER a listing produced
NURIs, and the listing is itself an anchored read of a not-yet-open index repo → 0 rows →
nothing to subscribe → nothing ever opens.

**Mechanism INFERRED, not established.** `resolve_target_for_sparql(Repo(id))`
(`engine/verifier/src/request_processor.rs`) does
`self.repos.get(repo_id).ok_or(RepoNotFound)`, so a repo genuinely absent from
`self.repos` should ERROR, not return 0 rows. The most plausible reading of the silent 0
is that the repo IS in `self.repos` (loaded from local user storage at bootstrap) while
its named graph in `graph_dataset` is not yet populated — commits not applied/synced yet
— so the query legitimately matches nothing. Not traced end to end; the tension with the
`RepoNotFound` path described in § *A repo is only queryable once OPENED/synced into the
store* is unresolved.

**Consequence for this lib:** a cold anchored read is NOT authoritative on its own — 0
rows does not mean absent. This is what imposes the open-then-read discipline on every
cold reader, and it is why the account trust root had to move behind a first-`State`
barrier (see § *The pointer → doc-shim indirection*).

### Account fork on concurrent provision — symptom VERIFIED, guarded polyfill-side, residue persists in wallets

On a fresh page, several independent callers hit `ensureAccount(A)` near-simultaneously
(the public and protected `watchShape`, container subscriptions, the app's owned-events
effect). When the account is genuinely new, each caller sees 0 and each provisions its
own set of three scope documents — an **in-session account fork**. The persisted residue
is a single account subject carrying MULTIPLE values for one scope predicate (observed:
five `shim:docPublic`), after which a writer and a later reader can resolve DIFFERENT
scope docs and the reader's anchored read returns 0.

Two polyfill-side guards, both in `packages/client/src/store-registry.ts`: `ensureInFlight`
(a bounded promise map keyed by account, so concurrent `ensureAccount` calls share ONE
resolve-or-provision) prevents new forks; `canonicalDoc` (pick the lexicographically
smallest NURI among all distinct values for a scope predicate — NURIs are
content-addressed, so the order is total and session-independent) makes resolution
deterministic on wallets that already carry fork residue. The earlier account-level
`provisionRetry` / `resolveAccountReliably` loop is gone, replaced by the doc-shim
barrier.

**Consequence for this lib:** the underlying enabler is core-side — there is no atomic
create-if-absent, and no existence probe to settle "does this account already exist?"
(see § *No existence probe at SDK level*), so provisioning is a read-then-create race the
polyfill has to serialize itself. The guards are mitigation, not a fix: a wallet already
corrupted stays corrupted, and only `canonicalDoc` keeps it readable.

### Outbox replay aborts on an unknown topic (`REPLAY TOPIC NOT FOUND`) — VERIFIED in core, already documented as an incident

`Verifier::send_outbox` (`engine/verifier/src/verifier.rs`) walks the queued events and,
for each, looks up `self.topics.get(&(overlay, topic_id))`. On a miss it logs
`REPLAY TOPIC NOT FOUND <topic> IN OVERLAY <overlay>` and sets `need_replay`, calls
`load_from_credentials_and_outbox(&events_to_replay)`, then in the send loop does
`self.topics.get(…).ok_or(NgError::TopicNotFound)?` — the `?` **aborts the whole outbox
flush**, so the remaining queued events are not sent. There is no per-event isolation and
no signal to the caller.

Already covered — **not duplicated here**: this is the core-side mechanism behind the
symptom described in § *Write loss on socket death (`SerializationError`)* above, whose
full post-mortem (logs, causal chain, the unarbitrated (i)/(ii) reserve) is
[`incidents/2026-07-14-write-loss-on-disconnect.md`](./incidents/2026-07-14-write-loss-on-disconnect.md).
The spontaneous socket death (`SOCKET IS CLOSED Some(Left(SerializationError))`) is
likewise covered there and in that section — the only fact added here is the abort
semantics of the replay path itself (VERIFIED by reading `send_outbox`).

**Consequence for this lib:** a queued write can be dropped without any observable error,
and one unknown topic can take the rest of the queue with it. The polyfill's own
`outbox-log.ts` does not record anything: it exports a single `inspectOutbox()` that
READS the SDK's own `sessionStorage` outbox and logs how many peers still have queued
writes. It observes the symptom; it holds nothing it could replay, and no
write-durability confirmation exists to await — so "the write returned" is not "the write
is durable".