mobile-api-keys: record what the client actually does now

The client half exists in monorepo-mobile as of f29774a, with OffChat as the
proof of concept, so this document is no longer purely forward-looking. Adds a
section covering what shipped, the two places the advice here was wrong about
the client — one key per app is not possible on mobile (shared-session puts one
credential in front of all nineteen apps), and signout was never the problem,
distress signout was — and two decisions worth a second opinion: clearing the
credential on 401 only, and leaving the traded-in JWT to expire rather than
blacklisting it, because that handler clears vault tokens keyed on the user.

docs/mobile-api-keys.md

@@ -6,6 +6,15 @@ planned-but-missing unless it says so.
 **The mobile apps are not built here.** This document is the boundary: what the server now accepts, what
 changes in `monorepo-mobile`, and what does not.
 
+> **Update, later on 2026-08-08 — the client side now exists, in `monorepo-mobile`.** `@officer/core`
+> gained `services/api-keys.ts` and `useAuth` learned that a key is a session; **OffChat (`apps/chat`) is
+> the proof of concept** and is the only app wired up. The other eighteen are untouched and behave
+> exactly as before.
+>
+> **None of it has been compiled or run** — it was written on the Linux box, which has no `node_modules`
+> for that repo and no Mac. Read §"What the client actually does now" for what shipped, what it changed
+> about the advice below, and the two things this document got wrong about the client.
+
 ---
 
 ## The short version
@@ -256,6 +265,61 @@ document was written, along with a WebSocket upgrade on `/api/cliamp/ws?token=<k
 
 ---
 
+## What the client actually does now
+
+Built in `monorepo-mobile` on 2026-08-08, against the server described above. **Written, never compiled**
+— no `node_modules` in that tree on this machine and no Mac, so not even `tsc` has seen it.
+
+### New in `@officer/core`
+
+- **`src/services/api-keys.ts`** — `listApiKeys` / `createApiKey` / `revokeApiKey`, `isApiKey`,
+  `defaultApiKeyName`, and `revokeApiKeyByCredential` (below). Shaped to mirror `dav.ts`'s app
+  passwords, which is the same mint-once-hash-forever contract.
+- **`src/services/device-name.ts`** — `deviceName()`, lifted out of `dav.ts`'s `deviceLabel()` so both
+  credential features name a device the same way. `deviceLabel()` now composes it; no caller changed.
+- **`useAuth`** — `signin(email, password, { deviceKeyName })` opts into path (a); `signInWithApiKey(key)`
+  is path (b).
+
+### Where this document was wrong about the client
+
+**1. There is no such thing as "one key per app" on mobile.** §(a) offers per-device or per-app as a free
+choice. It is not: `packages/core/src/services/shared-session.ts` holds **one token per server, shared
+across the whole suite** through an iOS keychain access group and an Android signature-permission
+ContentProvider. Whichever app writes last wins, for all of them. So a key named after an app actively
+misleads the owner about what revoking it disconnects — the answer is always "the device". The default
+name is `"<device> — <app>"`, where the app half records only who did the minting.
+
+**2. "Do not call signout with a key" was not the whole story — `distressSignout` was the real problem.**
+Under duress the app clears the credential locally _first_, then best-effort revokes server-side via
+`POST /api/auth/revoke`. That endpoint blacklists a JWT and does nothing whatever for a key, so the
+moment a phone starts holding keys, distress sign-out silently stops killing the credential. **And it
+matters more here than it ever did for a JWT: an unrevoked session token still expires in thirty days, an
+unrevoked key never does.**
+
+`revokeApiKeyByCredential(baseUrl, key)` is the fix — raw `fetch` (the credential is already out of
+storage by then, so it cannot go through `request()`), `GET /api/api-keys`, match on the `prefix` the
+server kept in the clear, `DELETE /api/api-keys/:id`.
+
+### Two client-side decisions worth a second opinion
+
+- **A 401 is now the only thing that clears the credential.** `useAuth`'s `/api/auth/me` query used to
+  clear on _any_ throw. A network error is `ApiError(0)` and a timeout is `ApiError(408)`, so launching
+  with no connectivity destroyed a working session and dropped the user at a login screen that needs the
+  network to be useful — and a 403 produced the logout loop this document warns about. Pre-existing, not
+  caused by keys, fixed while in there.
+- **The traded-in JWT is left to expire, not blacklisted.** Minting a key and keeping it drops a live
+  thirty-day token on the floor, and `POST /api/auth/signout` is the obvious tidy-up — but that handler
+  also calls `clearVaultTokens(user.id)`, keyed on the **user**, not the session. Blacklisting the
+  discarded token would therefore drop a vault session brokered on another of the owner's devices, as a
+  side effect of signing in. Not worth it for a token nothing holds and nothing will send again.
+
+### Still not built on the client
+
+No key-management screen in any app — listing and revoking remain web-only, per "Not built" above. The
+service verbs exist (`listApiKeys`, `revokeApiKey`) if that changes.
+
+---
+
 ## Where this lives on the server
 
 - `src/servers/auth-token.ts` — the key format and `resolveAuthToken`, the single function that turns a