Implements issue #4175 Wave 4 PR 21. Brokers OAuth 2.0 Device
Authorization Grant (RFC 8628) through the `qwen serve` daemon so a
remote SDK client can trigger a Qwen-account login whose tokens land
on the **daemon** filesystem, not on the client. The daemon polls the
IdP itself; the client's only job is to display the verification URL +
user code.

Runtime locality (#4175 §11): the daemon NEVER spawns a browser or
calls `open(url)` — even when running locally. Static-source grep
test fails the build on `node:child_process` / `open` / `xdg-open` /
`shell.openExternal` / `execa` / `shelljs` / `process.spawn` and
their dynamic-import / require variants.

- `POST /workspace/auth/device-flow` — strict mutation gate; returns
  201 fresh / 200 idempotent take-over with `attached: true`. Per
  per-`providerId` singleton: a second POST while pending takes over
  rather than allocating a new `device_code`.
- `GET /workspace/auth/device-flow/:id` — public state read. Pending
  entries echo `userCode/verificationUri/expiresAt/intervalMs`;
  terminal entries (5-min grace) drop them and surface
  `status/errorKind/hint`.
- `DELETE /workspace/auth/device-flow/:id` — strict; idempotent
  (terminal → 204 no-op; unknown → 404).
- `GET /workspace/auth/status` — pending flows + supported providers
  snapshot. v1 stub for `providers: []` (populated in fold-in 1).

`DeviceFlowRegistry` (`packages/cli/src/serve/auth/deviceFlow.ts`)
is the in-memory state holder:
- per-`providerId` singleton with idempotent take-over
- workspace-wide cap of 4 active flows (abuse defense)
- 5-min terminal grace so SDK reconnects can still observe results
- TTL sweeper evicts grace-expired entries every 30s
- in-flight `Promise` map coalesces concurrent `start()` calls so two
  parallel POSTs don't double-allocate IdP `device_code`
- `transitionTerminal` returns `boolean` so caller-side emit/audit
  guard prevents sweeper × poll-tick double-fire
- `dispose()` wired into `runQwenServe.close()`'s shutdown drain;
  cancels `provider.poll()` mid-flight via `cancelController`,
  records `lost_success` audit when an IdP-minted token is dropped
  by transition

`DeviceFlowProvider` interface accepts `start({signal})` +
`poll(state, {signal})`. `QwenOAuthDeviceFlowProvider` wraps the
existing `QwenOAuth2Client.requestDeviceAuthorization` /
`pollDeviceToken` primitives directly (NOT
`authWithQwenDeviceFlow`, which calls `open(url)`). PKCE is
provider-required by Qwen but optional in the interface for future
non-PKCE providers. `success.persist()` writes to disk FIRST, then
updates the in-process client — a failed disk write no longer
leaves the daemon with a zombie in-memory token. Maps RFC 8628
errors via an anchored regex (`^Device token poll failed:
(expired_token|access_denied|invalid_grant)`) so an
`error_description` containing one of those literals can't
mis-classify an unrelated upstream error.

`BrandedSecret<T extends string>` holds the `device_code` and PKCE
verifier. Earlier draft used `new String()` wrapper which leaked
through `+` / template literals (`Symbol.toPrimitive` →
`valueOf` returned the primitive). Final shape: frozen plain object
+ `WeakMap` indirection + 4-way redaction
(`toString` / `toJSON` / `Symbol.toPrimitive` / numeric coercion →
`'[redacted]'` or `NaN`) + `unique symbol` brand. 6 leak-path
tests: `JSON.stringify` / `String()` / concat / template / `+x` /
reveal-roundtrip.

5 new daemon events (workspace-scoped, fanned out to every active
session bus via `bridge.broadcastWorkspaceEvent`):

- `auth_device_flow_started` — `{deviceFlowId, providerId, expiresAt}`
  (no userCode/verificationUri — see PR 21 design §3)
- `auth_device_flow_throttled` — `{deviceFlowId, intervalMs}`,
  emitted only on upstream `slow_down` interval bumps
- `auth_device_flow_authorized` — `{deviceFlowId, providerId,
  expiresAt?, accountAlias?}`; `accountAlias` is best-effort
  non-PII (never email/phone)
- `auth_device_flow_failed` — `{deviceFlowId, errorKind, hint?}`
  with `errorKind ∈ {expired_token, access_denied, invalid_grant,
  upstream_error, persist_failed}`
- `auth_device_flow_cancelled` — `{deviceFlowId}` (DELETE on pending)

Workspace-scoped reducer `reduceDaemonAuthEvent` produces
`DaemonAuthState { flows: Partial<Record<ProviderId, ...>> }` —
parallel to `reduceDaemonSessionEvent`. Session reducer no-ops on
auth events (workspace-scoped state belongs in its own reducer).

`bridge.broadcastWorkspaceEvent` is intentionally distinct from PR
16's `publishWorkspaceEvent` to avoid merge conflict; collapses to
the shared helper as a fold-in once #4249 lands (~25 LoC).

`@qwen-code/sdk` (`packages/sdk-typescript/`):

- 4 new `DaemonClient` methods: `startDeviceFlow`, `getDeviceFlow`,
  `cancelDeviceFlow`, `getAuthStatus` — typed against the wire
  shapes, errors mapped through the existing `DaemonHttpError`.
- High-level `client.auth` getter (lazy `DaemonAuthFlow` singleton)
  exposes a `start(...).awaitCompletion()` shape mirroring `gh auth
  login`'s UX: print code first, let the SDK consumer decide where
  to open the browser. `awaitCompletion` polls GET on the
  daemon-supplied `intervalMs`, honors `slow_down` bumps, and
  fall-back-recovers from 404 (entry evicted post-grace).

POST + DELETE flow through PR 15's `mutate({strict: true})` —
401 `token_required` on token-less loopback defaults. GET routes
use only the global `bearerAuth`. Every state transition
(`started/authorized/failed/cancelled/expired/lost_success`)
records a structured stderr breadcrumb (`[serve] auth.device-flow:
provider=... deviceFlowId=abc12... clientId=... status=...`)
since `mutate()` doesn't carry an audit hook — events alone aren't
enough since SDK can silently drop them; stderr → journald/docker
logs is the unfalsifiable record.

`auth_device_flow` advertised unconditionally on
`/capabilities.features`. Supported providers list lives on
`/workspace/auth/status` to keep the registry descriptor uniform.

- `packages/core/src/qwen/qwenOAuth2.ts`:
  - exports `cacheQwenCredentials` (was a private function; needed
    by the daemon's device-flow registry)
  - `cacheQwenCredentials` now calls `SharedTokenManager.clearCache()`
    after writing, folding what was previously a paired call site at
    L820+L829. Idempotent change.
  - file mode `0o600` on `oauth_creds.json` (was default 0o666 +
    umask). Mirrors opencode's `auth/index.ts`.
- `packages/cli/src/serve/runQwenServe.ts`: device-flow registry
  `dispose()` wired into the shutdown drain (BEFORE
  `bridge.shutdown()`).

- `auth/deviceFlow.test.ts` — 21 tests: BrandedSecret leak paths,
  state machine (slow_down / success / error), terminal grace,
  concurrent-start coalescing, dispose, cancel idempotency, static-
  source grep against browser-spawn primitives.
- `server.test.ts` — 10 device-flow integration tests:
  POST 201/200 take-over, strict 401, 400 `unsupported_provider`,
  GET / DELETE / `/workspace/auth/status`, 502 `upstream_error`
  mapping, sweeper-driven auto-expiry with controlled clock,
  capability advertisement.
- `daemonEvents.test.ts` — 5 SDK reducer tests: type guards, per-
  provider state projection, `failed` always → `status: 'error'`
  (errorKind carries the kind, including new `persist_failed`),
  session reducer no-ops on auth events.

369/369 serve + SDK tests pass; typecheck + `eslint
--max-warnings 0` clean across 14 PR 21 files.

- [x] Independently mergeable (depends only on merged PR 4 / PR 7 /
      PR 12 / PR 15)
- [x] Backward compatible (4 new routes + 1 capability tag + 5 typed
      events + 4 SDK helpers; existing routes/events untouched)
- [x] Default off (capability advertised but no client is forced to
      use it; CLI `qwen` OAuth flow unchanged)
- [x] `qwen serve` Stage 1 routes / SDK behavior preserved
- [x] Gradual migration (v1 only `qwen-oauth`; future providers
      register through the `DeviceFlowProvider` interface)
- [x] Reversible (revert removes 4 routes + 1 tag + 5 events with no
      schema migration)
- [x] Tests-first (28 new tests across 3 layers)

- Inline `bridge.broadcastWorkspaceEvent` → fold-in to PR 16 (#4249)
  `publishWorkspaceEvent` once that lands
- `/workspace/auth/status` vs PR 12 `/workspace/providers` boundary
  — separate route in v1; merge alternative discussed
- Wave 4 PRs 17/19/20 should adopt the same mutate-strict +
  workspace event-fan-out pattern

5 items from pre-PR specialist passes parked for a focused
follow-up: `DeviceFlowEntry` discriminated union, single-source SDK
status / ProviderId unions, `awaitCompletion` memoization,
broadcast-100%-fail stderr elevation, SDK 404 →
`not_found_or_evicted` errorKind.

Refs: #4175

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

Implements issue #4175 Wave 4 PR 21. Brokers OAuth 2.0 Device
Authorization Grant (RFC 8628) through the `qwen serve` daemon so a
remote SDK client can trigger a Qwen-account login whose tokens land
on the **daemon** filesystem, not on the client. The daemon polls the
IdP itself; the client's only job is to display the verification URL +
user code.

Runtime locality (#4175 §11): the daemon NEVER spawns a browser or
calls `open(url)` — even when running locally. Static-source grep
test fails the build on `node:child_process` / `open` / `xdg-open` /
`shell.openExternal` / `execa` / `shelljs` / `process.spawn` and
their dynamic-import / require variants.

- `POST /workspace/auth/device-flow` — strict mutation gate; returns
  201 fresh / 200 idempotent take-over with `attached: true`. Per
  per-`providerId` singleton: a second POST while pending takes over
  rather than allocating a new `device_code`.
- `GET /workspace/auth/device-flow/:id` — public state read. Pending
  entries echo `userCode/verificationUri/expiresAt/intervalMs`;
  terminal entries (5-min grace) drop them and surface
  `status/errorKind/hint`.
- `DELETE /workspace/auth/device-flow/:id` — strict; idempotent
  (terminal → 204 no-op; unknown → 404).
- `GET /workspace/auth/status` — pending flows + supported providers
  snapshot. v1 stub for `providers: []` (populated in fold-in 1).

`DeviceFlowRegistry` (`packages/cli/src/serve/auth/deviceFlow.ts`)
is the in-memory state holder:
- per-`providerId` singleton with idempotent take-over
- workspace-wide cap of 4 active flows (abuse defense)
- 5-min terminal grace so SDK reconnects can still observe results
- TTL sweeper evicts grace-expired entries every 30s
- in-flight `Promise` map coalesces concurrent `start()` calls so two
  parallel POSTs don't double-allocate IdP `device_code`
- `transitionTerminal` returns `boolean` so caller-side emit/audit
  guard prevents sweeper × poll-tick double-fire
- `dispose()` wired into `runQwenServe.close()`'s shutdown drain;
  cancels `provider.poll()` mid-flight via `cancelController`,
  records `lost_success` audit when an IdP-minted token is dropped
  by transition

`DeviceFlowProvider` interface accepts `start({signal})` +
`poll(state, {signal})`. `QwenOAuthDeviceFlowProvider` wraps the
existing `QwenOAuth2Client.requestDeviceAuthorization` /
`pollDeviceToken` primitives directly (NOT
`authWithQwenDeviceFlow`, which calls `open(url)`). PKCE is
provider-required by Qwen but optional in the interface for future
non-PKCE providers. `success.persist()` writes to disk FIRST, then
updates the in-process client — a failed disk write no longer
leaves the daemon with a zombie in-memory token. Maps RFC 8628
errors via an anchored regex (`^Device token poll failed:
(expired_token|access_denied|invalid_grant)`) so an
`error_description` containing one of those literals can't
mis-classify an unrelated upstream error.

`BrandedSecret<T extends string>` holds the `device_code` and PKCE
verifier. Earlier draft used `new String()` wrapper which leaked
through `+` / template literals (`Symbol.toPrimitive` →
`valueOf` returned the primitive). Final shape: frozen plain object
+ `WeakMap` indirection + 4-way redaction
(`toString` / `toJSON` / `Symbol.toPrimitive` / numeric coercion →
`'[redacted]'` or `NaN`) + `unique symbol` brand. 6 leak-path
tests: `JSON.stringify` / `String()` / concat / template / `+x` /
reveal-roundtrip.

5 new daemon events (workspace-scoped, fanned out to every active
session bus via `bridge.broadcastWorkspaceEvent`):

- `auth_device_flow_started` — `{deviceFlowId, providerId, expiresAt}`
  (no userCode/verificationUri — see PR 21 design §3)
- `auth_device_flow_throttled` — `{deviceFlowId, intervalMs}`,
  emitted only on upstream `slow_down` interval bumps
- `auth_device_flow_authorized` — `{deviceFlowId, providerId,
  expiresAt?, accountAlias?}`; `accountAlias` is best-effort
  non-PII (never email/phone)
- `auth_device_flow_failed` — `{deviceFlowId, errorKind, hint?}`
  with `errorKind ∈ {expired_token, access_denied, invalid_grant,
  upstream_error, persist_failed}`
- `auth_device_flow_cancelled` — `{deviceFlowId}` (DELETE on pending)

Workspace-scoped reducer `reduceDaemonAuthEvent` produces
`DaemonAuthState { flows: Partial<Record<ProviderId, ...>> }` —
parallel to `reduceDaemonSessionEvent`. Session reducer no-ops on
auth events (workspace-scoped state belongs in its own reducer).

`bridge.broadcastWorkspaceEvent` is intentionally distinct from PR
16's `publishWorkspaceEvent` to avoid merge conflict; collapses to
the shared helper as a fold-in once #4249 lands (~25 LoC).

`@qwen-code/sdk` (`packages/sdk-typescript/`):

- 4 new `DaemonClient` methods: `startDeviceFlow`, `getDeviceFlow`,
  `cancelDeviceFlow`, `getAuthStatus` — typed against the wire
  shapes, errors mapped through the existing `DaemonHttpError`.
- High-level `client.auth` getter (lazy `DaemonAuthFlow` singleton)
  exposes a `start(...).awaitCompletion()` shape mirroring `gh auth
  login`'s UX: print code first, let the SDK consumer decide where
  to open the browser. `awaitCompletion` polls GET on the
  daemon-supplied `intervalMs`, honors `slow_down` bumps, and
  fall-back-recovers from 404 (entry evicted post-grace).

POST + DELETE flow through PR 15's `mutate({strict: true})` —
401 `token_required` on token-less loopback defaults. GET routes
use only the global `bearerAuth`. Every state transition
(`started/authorized/failed/cancelled/expired/lost_success`)
records a structured stderr breadcrumb (`[serve] auth.device-flow:
provider=... deviceFlowId=abc12... clientId=... status=...`)
since `mutate()` doesn't carry an audit hook — events alone aren't
enough since SDK can silently drop them; stderr → journald/docker
logs is the unfalsifiable record.

`auth_device_flow` advertised unconditionally on
`/capabilities.features`. Supported providers list lives on
`/workspace/auth/status` to keep the registry descriptor uniform.

- `packages/core/src/qwen/qwenOAuth2.ts`:
  - exports `cacheQwenCredentials` (was a private function; needed
    by the daemon's device-flow registry)
  - `cacheQwenCredentials` now calls `SharedTokenManager.clearCache()`
    after writing, folding what was previously a paired call site at
    L820+L829. Idempotent change.
  - file mode `0o600` on `oauth_creds.json` (was default 0o666 +
    umask). Mirrors opencode's `auth/index.ts`.
- `packages/cli/src/serve/runQwenServe.ts`: device-flow registry
  `dispose()` wired into the shutdown drain (BEFORE
  `bridge.shutdown()`).

- `auth/deviceFlow.test.ts` — 21 tests: BrandedSecret leak paths,
  state machine (slow_down / success / error), terminal grace,
  concurrent-start coalescing, dispose, cancel idempotency, static-
  source grep against browser-spawn primitives.
- `server.test.ts` — 10 device-flow integration tests:
  POST 201/200 take-over, strict 401, 400 `unsupported_provider`,
  GET / DELETE / `/workspace/auth/status`, 502 `upstream_error`
  mapping, sweeper-driven auto-expiry with controlled clock,
  capability advertisement.
- `daemonEvents.test.ts` — 5 SDK reducer tests: type guards, per-
  provider state projection, `failed` always → `status: 'error'`
  (errorKind carries the kind, including new `persist_failed`),
  session reducer no-ops on auth events.

369/369 serve + SDK tests pass; typecheck + `eslint
--max-warnings 0` clean across 14 PR 21 files.

- [x] Independently mergeable (depends only on merged PR 4 / PR 7 /
      PR 12 / PR 15)
- [x] Backward compatible (4 new routes + 1 capability tag + 5 typed
      events + 4 SDK helpers; existing routes/events untouched)
- [x] Default off (capability advertised but no client is forced to
      use it; CLI `qwen` OAuth flow unchanged)
- [x] `qwen serve` Stage 1 routes / SDK behavior preserved
- [x] Gradual migration (v1 only `qwen-oauth`; future providers
      register through the `DeviceFlowProvider` interface)
- [x] Reversible (revert removes 4 routes + 1 tag + 5 events with no
      schema migration)
- [x] Tests-first (28 new tests across 3 layers)

- Inline `bridge.broadcastWorkspaceEvent` → fold-in to PR 16 (#4249)
  `publishWorkspaceEvent` once that lands
- `/workspace/auth/status` vs PR 12 `/workspace/providers` boundary
  — separate route in v1; merge alternative discussed
- Wave 4 PRs 17/19/20 should adopt the same mutate-strict +
  workspace event-fan-out pattern

5 items from pre-PR specialist passes parked for a focused
follow-up: `DeviceFlowEntry` discriminated union, single-source SDK
status / ProviderId unions, `awaitCompletion` memoization,
broadcast-100%-fail stderr elevation, SDK 404 →
`not_found_or_evicted` errorKind.

Refs: #4175

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

Implements issue #4175 Wave 4 PR 21. Brokers OAuth 2.0 Device
Authorization Grant (RFC 8628) through the `qwen serve` daemon so a
remote SDK client can trigger a Qwen-account login whose tokens land
on the **daemon** filesystem, not on the client. The daemon polls the
IdP itself; the client's only job is to display the verification URL +
user code.

Runtime locality (#4175 §11): the daemon NEVER spawns a browser or
calls `open(url)` — even when running locally. Static-source grep
test fails the build on `node:child_process` / `open` / `xdg-open` /
`shell.openExternal` / `execa` / `shelljs` / `process.spawn` and
their dynamic-import / require variants.

- `POST /workspace/auth/device-flow` — strict mutation gate; returns
  201 fresh / 200 idempotent take-over with `attached: true`. Per
  per-`providerId` singleton: a second POST while pending takes over
  rather than allocating a new `device_code`.
- `GET /workspace/auth/device-flow/:id` — public state read. Pending
  entries echo `userCode/verificationUri/expiresAt/intervalMs`;
  terminal entries (5-min grace) drop them and surface
  `status/errorKind/hint`.
- `DELETE /workspace/auth/device-flow/:id` — strict; idempotent
  (terminal → 204 no-op; unknown → 404).
- `GET /workspace/auth/status` — pending flows + supported providers
  snapshot. v1 stub for `providers: []` (populated in fold-in 1).

`DeviceFlowRegistry` (`packages/cli/src/serve/auth/deviceFlow.ts`)
is the in-memory state holder:
- per-`providerId` singleton with idempotent take-over
- workspace-wide cap of 4 active flows (abuse defense)
- 5-min terminal grace so SDK reconnects can still observe results
- TTL sweeper evicts grace-expired entries every 30s
- in-flight `Promise` map coalesces concurrent `start()` calls so two
  parallel POSTs don't double-allocate IdP `device_code`
- `transitionTerminal` returns `boolean` so caller-side emit/audit
  guard prevents sweeper × poll-tick double-fire
- `dispose()` wired into `runQwenServe.close()`'s shutdown drain;
  cancels `provider.poll()` mid-flight via `cancelController`,
  records `lost_success` audit when an IdP-minted token is dropped
  by transition

`DeviceFlowProvider` interface accepts `start({signal})` +
`poll(state, {signal})`. `QwenOAuthDeviceFlowProvider` wraps the
existing `QwenOAuth2Client.requestDeviceAuthorization` /
`pollDeviceToken` primitives directly (NOT
`authWithQwenDeviceFlow`, which calls `open(url)`). PKCE is
provider-required by Qwen but optional in the interface for future
non-PKCE providers. `success.persist()` writes to disk FIRST, then
updates the in-process client — a failed disk write no longer
leaves the daemon with a zombie in-memory token. Maps RFC 8628
errors via an anchored regex (`^Device token poll failed:
(expired_token|access_denied|invalid_grant)`) so an
`error_description` containing one of those literals can't
mis-classify an unrelated upstream error.

`BrandedSecret<T extends string>` holds the `device_code` and PKCE
verifier. Earlier draft used `new String()` wrapper which leaked
through `+` / template literals (`Symbol.toPrimitive` →
`valueOf` returned the primitive). Final shape: frozen plain object
+ `WeakMap` indirection + 4-way redaction
(`toString` / `toJSON` / `Symbol.toPrimitive` / numeric coercion →
`'[redacted]'` or `NaN`) + `unique symbol` brand. 6 leak-path
tests: `JSON.stringify` / `String()` / concat / template / `+x` /
reveal-roundtrip.

5 new daemon events (workspace-scoped, fanned out to every active
session bus via `bridge.broadcastWorkspaceEvent`):

- `auth_device_flow_started` — `{deviceFlowId, providerId, expiresAt}`
  (no userCode/verificationUri — see PR 21 design §3)
- `auth_device_flow_throttled` — `{deviceFlowId, intervalMs}`,
  emitted only on upstream `slow_down` interval bumps
- `auth_device_flow_authorized` — `{deviceFlowId, providerId,
  expiresAt?, accountAlias?}`; `accountAlias` is best-effort
  non-PII (never email/phone)
- `auth_device_flow_failed` — `{deviceFlowId, errorKind, hint?}`
  with `errorKind ∈ {expired_token, access_denied, invalid_grant,
  upstream_error, persist_failed}`
- `auth_device_flow_cancelled` — `{deviceFlowId}` (DELETE on pending)

Workspace-scoped reducer `reduceDaemonAuthEvent` produces
`DaemonAuthState { flows: Partial<Record<ProviderId, ...>> }` —
parallel to `reduceDaemonSessionEvent`. Session reducer no-ops on
auth events (workspace-scoped state belongs in its own reducer).

`bridge.broadcastWorkspaceEvent` is intentionally distinct from PR
16's `publishWorkspaceEvent` to avoid merge conflict; collapses to
the shared helper as a fold-in once #4249 lands (~25 LoC).

`@qwen-code/sdk` (`packages/sdk-typescript/`):

- 4 new `DaemonClient` methods: `startDeviceFlow`, `getDeviceFlow`,
  `cancelDeviceFlow`, `getAuthStatus` — typed against the wire
  shapes, errors mapped through the existing `DaemonHttpError`.
- High-level `client.auth` getter (lazy `DaemonAuthFlow` singleton)
  exposes a `start(...).awaitCompletion()` shape mirroring `gh auth
  login`'s UX: print code first, let the SDK consumer decide where
  to open the browser. `awaitCompletion` polls GET on the
  daemon-supplied `intervalMs`, honors `slow_down` bumps, and
  fall-back-recovers from 404 (entry evicted post-grace).

POST + DELETE flow through PR 15's `mutate({strict: true})` —
401 `token_required` on token-less loopback defaults. GET routes
use only the global `bearerAuth`. Every state transition
(`started/authorized/failed/cancelled/expired/lost_success`)
records a structured stderr breadcrumb (`[serve] auth.device-flow:
provider=... deviceFlowId=abc12... clientId=... status=...`)
since `mutate()` doesn't carry an audit hook — events alone aren't
enough since SDK can silently drop them; stderr → journald/docker
logs is the unfalsifiable record.

`auth_device_flow` advertised unconditionally on
`/capabilities.features`. Supported providers list lives on
`/workspace/auth/status` to keep the registry descriptor uniform.

- `packages/core/src/qwen/qwenOAuth2.ts`:
  - exports `cacheQwenCredentials` (was a private function; needed
    by the daemon's device-flow registry)
  - `cacheQwenCredentials` now calls `SharedTokenManager.clearCache()`
    after writing, folding what was previously a paired call site at
    L820+L829. Idempotent change.
  - file mode `0o600` on `oauth_creds.json` (was default 0o666 +
    umask). Mirrors opencode's `auth/index.ts`.
- `packages/cli/src/serve/runQwenServe.ts`: device-flow registry
  `dispose()` wired into the shutdown drain (BEFORE
  `bridge.shutdown()`).

- `auth/deviceFlow.test.ts` — 21 tests: BrandedSecret leak paths,
  state machine (slow_down / success / error), terminal grace,
  concurrent-start coalescing, dispose, cancel idempotency, static-
  source grep against browser-spawn primitives.
- `server.test.ts` — 10 device-flow integration tests:
  POST 201/200 take-over, strict 401, 400 `unsupported_provider`,
  GET / DELETE / `/workspace/auth/status`, 502 `upstream_error`
  mapping, sweeper-driven auto-expiry with controlled clock,
  capability advertisement.
- `daemonEvents.test.ts` — 5 SDK reducer tests: type guards, per-
  provider state projection, `failed` always → `status: 'error'`
  (errorKind carries the kind, including new `persist_failed`),
  session reducer no-ops on auth events.

369/369 serve + SDK tests pass; typecheck + `eslint
--max-warnings 0` clean across 14 PR 21 files.

- [x] Independently mergeable (depends only on merged PR 4 / PR 7 /
      PR 12 / PR 15)
- [x] Backward compatible (4 new routes + 1 capability tag + 5 typed
      events + 4 SDK helpers; existing routes/events untouched)
- [x] Default off (capability advertised but no client is forced to
      use it; CLI `qwen` OAuth flow unchanged)
- [x] `qwen serve` Stage 1 routes / SDK behavior preserved
- [x] Gradual migration (v1 only `qwen-oauth`; future providers
      register through the `DeviceFlowProvider` interface)
- [x] Reversible (revert removes 4 routes + 1 tag + 5 events with no
      schema migration)
- [x] Tests-first (28 new tests across 3 layers)

- Inline `bridge.broadcastWorkspaceEvent` → fold-in to PR 16 (#4249)
  `publishWorkspaceEvent` once that lands
- `/workspace/auth/status` vs PR 12 `/workspace/providers` boundary
  — separate route in v1; merge alternative discussed
- Wave 4 PRs 17/19/20 should adopt the same mutate-strict +
  workspace event-fan-out pattern

5 items from pre-PR specialist passes parked for a focused
follow-up: `DeviceFlowEntry` discriminated union, single-source SDK
status / ProviderId unions, `awaitCompletion` memoization,
broadcast-100%-fail stderr elevation, SDK 404 →
`not_found_or_evicted` errorKind.

Refs: #4175

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

Keep demo.ts import alongside new workspaceMemory and workspaceAgents imports.

Twelve correctness + structural fixes from a wenshao + DeepSeek + gpt-5.5
review pass. Tests deferred to fold-in 10 (separate, larger commit).

CRITICAL CORRECTNESS

#7 — `provider.persist()` Promise.race could publish `persist_failed`
to SSE while a non-cooperative provider was still committing
credentials to disk. Added an independent tracker on the original
persist promise: if the race timed out (`persistTimedOut === true`)
AND the underlying persist later resolved successfully, audit a
`lost_success_after_timeout` breadcrumb so operators see the
inconsistency. Tightened the persist `@remarks` contract to require
signal honoring end-to-end. Qwen provider already complies (fold-in
3 #10); this is forward-defense for future providers.

#11 — auth surface (`DaemonAuthFlow`, `reduceDaemonAuthEvent`,
`createDaemonAuthState`, `DEVICE_FLOW_EXPIRY_GRACE_MS`, all event /
data / state types) was re-exported from `src/daemon/index.ts` but
NEVER from the published SDK entry `src/index.ts`. SDK consumers got
`undefined` for everything except `client.auth.start()` (which
traveled through the already-exported `DaemonClient`). Added the
missing exports and pinned via `daemon-public-surface.test.ts`.

#12 — `core/src/qwen/qwenOAuth2.ts:373`'s
`debugLogger.debug('Device authorization result:', result)` writes
the raw `device_code` (RFC 8628 bearer-equivalent credential) to
stderr / journald, bypassing the `BrandedSecret` redaction layer.
Pre-existing on main but PR 21 expanded the exposure surface.
Sanitized to log only `{ ok, expires_in }` on success / `{ ok,
error }` on error.

#13 — `runPollTick` success-branch persist-failure × past-`expiresAt`
classified as `expired_token` instead of `persist_failed`, routing
operators toward "tell user to retry" (RFC 8628 expiry) when the
actual root cause was disk I/O. Reclassified to `persist_failed`
with a `persist_also_failed_past_expiry` audit hint to preserve the
timing detail for incident response.

SMALL CORRECTNESS

#1 — `runPollTick` catch hint replaced with a STATIC bounded message
("provider.poll() failed; see daemon audit log for details"). The
fold-in 8 truncated-prefix approach could still leak the first 256
chars of provider-templated raw text including secret material. Full
raw still routed to audit channel for operator visibility.

#5 — `cancellerClientId` field added to `DeviceFlowEntry`; deferred-
cancel branch in `cancel()` now stamps it on the entry, and the
persist-resolution `cancelled` event publish uses
`entry.cancellerClientId ?? entry.initiatorClientId`. SSE consumers
that suppress self-emitted events can now attribute the cancel
correctly.

#6 — `AwaitCompletionOptions.timeoutMs === 0` (the documented
"settle immediately, return current daemon view" contract) was
treated as falsy by the `?` ternary, falling back to the default.
`sanitizePositiveMs` now takes an `allowZero` opt-in; the ceiling
computation uses `!== undefined` instead of truthy check.

#8 — `EventBus.publish()` returns `undefined` for closed buses (it
does NOT throw). `broadcastWorkspaceEvent` previously counted that
path as success, hiding the all-buses-dropped operator alarm.
Folded the closed-bus-as-failure check into the canonical
`publishWorkspaceEvent` (see #X below).

#9 — start-timeout Promise.race rejected with a plain `Error`,
falling through `sendBridgeError` to a generic 500. Switched to
`UpstreamDeviceFlowError` so a hung IdP correctly surfaces as 502
(matching the envelope every other IdP start failure uses).

STRUCTURAL

#3 — Three identical `transitionTerminal + publish + audit`
expired_token blocks in `runPollTick`/`sweep`/(removed by #13)
deduplicated into a private `expireEntry()` helper. Future event-
shape changes are now a one-edit operation.

#X — PR 16 (#4249) merged on 2026-05-18 06:27Z. Per the inline
comment at httpAcpBridge.ts:501, PR 21's `broadcastWorkspaceEvent`
was kept distinct only to avoid the merge conflict; once PR 16
landed, it became a fold-in candidate. Folded the closed-bus +
all-failed-stderr-escalation operator-visibility features (PR 21's
S5 + fold-in 9 #8) INTO `publishWorkspaceEvent`; dropped
`broadcastWorkspaceEvent` from the bridge interface + impl + test
mocks. PR 21's deviceFlowEventSink now calls
`bridge.publishWorkspaceEvent` — single canonical workspace fan-out.

DOC

#16 — Added a "Cross-client take-over" paragraph to
`docs/users/qwen-serve.md` explaining that two clients on the same
daemon for the same provider get the per-provider singleton with
`attached: true`/`false` distinguishing them; no separate event
fires (both eventually observe the same `auth_device_flow_authorized`).

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

Implements issue #4175 Wave 4 PR 21. Brokers OAuth 2.0 Device
Authorization Grant (RFC 8628) through the `qwen serve` daemon so a
remote SDK client can trigger a Qwen-account login whose tokens land
on the **daemon** filesystem, not on the client. The daemon polls the
IdP itself; the client's only job is to display the verification URL +
user code.

Runtime locality (#4175 §11): the daemon NEVER spawns a browser or
calls `open(url)` — even when running locally. Static-source grep
test fails the build on `node:child_process` / `open` / `xdg-open` /
`shell.openExternal` / `execa` / `shelljs` / `process.spawn` and
their dynamic-import / require variants.

- `POST /workspace/auth/device-flow` — strict mutation gate; returns
  201 fresh / 200 idempotent take-over with `attached: true`. Per
  per-`providerId` singleton: a second POST while pending takes over
  rather than allocating a new `device_code`.
- `GET /workspace/auth/device-flow/:id` — public state read. Pending
  entries echo `userCode/verificationUri/expiresAt/intervalMs`;
  terminal entries (5-min grace) drop them and surface
  `status/errorKind/hint`.
- `DELETE /workspace/auth/device-flow/:id` — strict; idempotent
  (terminal → 204 no-op; unknown → 404).
- `GET /workspace/auth/status` — pending flows + supported providers
  snapshot. v1 stub for `providers: []` (populated in fold-in 1).

`DeviceFlowRegistry` (`packages/cli/src/serve/auth/deviceFlow.ts`)
is the in-memory state holder:
- per-`providerId` singleton with idempotent take-over
- workspace-wide cap of 4 active flows (abuse defense)
- 5-min terminal grace so SDK reconnects can still observe results
- TTL sweeper evicts grace-expired entries every 30s
- in-flight `Promise` map coalesces concurrent `start()` calls so two
  parallel POSTs don't double-allocate IdP `device_code`
- `transitionTerminal` returns `boolean` so caller-side emit/audit
  guard prevents sweeper × poll-tick double-fire
- `dispose()` wired into `runQwenServe.close()`'s shutdown drain;
  cancels `provider.poll()` mid-flight via `cancelController`,
  records `lost_success` audit when an IdP-minted token is dropped
  by transition

`DeviceFlowProvider` interface accepts `start({signal})` +
`poll(state, {signal})`. `QwenOAuthDeviceFlowProvider` wraps the
existing `QwenOAuth2Client.requestDeviceAuthorization` /
`pollDeviceToken` primitives directly (NOT
`authWithQwenDeviceFlow`, which calls `open(url)`). PKCE is
provider-required by Qwen but optional in the interface for future
non-PKCE providers. `success.persist()` writes to disk FIRST, then
updates the in-process client — a failed disk write no longer
leaves the daemon with a zombie in-memory token. Maps RFC 8628
errors via an anchored regex (`^Device token poll failed:
(expired_token|access_denied|invalid_grant)`) so an
`error_description` containing one of those literals can't
mis-classify an unrelated upstream error.

`BrandedSecret<T extends string>` holds the `device_code` and PKCE
verifier. Earlier draft used `new String()` wrapper which leaked
through `+` / template literals (`Symbol.toPrimitive` →
`valueOf` returned the primitive). Final shape: frozen plain object
+ `WeakMap` indirection + 4-way redaction
(`toString` / `toJSON` / `Symbol.toPrimitive` / numeric coercion →
`'[redacted]'` or `NaN`) + `unique symbol` brand. 6 leak-path
tests: `JSON.stringify` / `String()` / concat / template / `+x` /
reveal-roundtrip.

5 new daemon events (workspace-scoped, fanned out to every active
session bus via `bridge.broadcastWorkspaceEvent`):

- `auth_device_flow_started` — `{deviceFlowId, providerId, expiresAt}`
  (no userCode/verificationUri — see PR 21 design §3)
- `auth_device_flow_throttled` — `{deviceFlowId, intervalMs}`,
  emitted only on upstream `slow_down` interval bumps
- `auth_device_flow_authorized` — `{deviceFlowId, providerId,
  expiresAt?, accountAlias?}`; `accountAlias` is best-effort
  non-PII (never email/phone)
- `auth_device_flow_failed` — `{deviceFlowId, errorKind, hint?}`
  with `errorKind ∈ {expired_token, access_denied, invalid_grant,
  upstream_error, persist_failed}`
- `auth_device_flow_cancelled` — `{deviceFlowId}` (DELETE on pending)

Workspace-scoped reducer `reduceDaemonAuthEvent` produces
`DaemonAuthState { flows: Partial<Record<ProviderId, ...>> }` —
parallel to `reduceDaemonSessionEvent`. Session reducer no-ops on
auth events (workspace-scoped state belongs in its own reducer).

`bridge.broadcastWorkspaceEvent` is intentionally distinct from PR
16's `publishWorkspaceEvent` to avoid merge conflict; collapses to
the shared helper as a fold-in once #4249 lands (~25 LoC).

`@qwen-code/sdk` (`packages/sdk-typescript/`):

- 4 new `DaemonClient` methods: `startDeviceFlow`, `getDeviceFlow`,
  `cancelDeviceFlow`, `getAuthStatus` — typed against the wire
  shapes, errors mapped through the existing `DaemonHttpError`.
- High-level `client.auth` getter (lazy `DaemonAuthFlow` singleton)
  exposes a `start(...).awaitCompletion()` shape mirroring `gh auth
  login`'s UX: print code first, let the SDK consumer decide where
  to open the browser. `awaitCompletion` polls GET on the
  daemon-supplied `intervalMs`, honors `slow_down` bumps, and
  fall-back-recovers from 404 (entry evicted post-grace).

POST + DELETE flow through PR 15's `mutate({strict: true})` —
401 `token_required` on token-less loopback defaults. GET routes
use only the global `bearerAuth`. Every state transition
(`started/authorized/failed/cancelled/expired/lost_success`)
records a structured stderr breadcrumb (`[serve] auth.device-flow:
provider=... deviceFlowId=abc12... clientId=... status=...`)
since `mutate()` doesn't carry an audit hook — events alone aren't
enough since SDK can silently drop them; stderr → journald/docker
logs is the unfalsifiable record.

`auth_device_flow` advertised unconditionally on
`/capabilities.features`. Supported providers list lives on
`/workspace/auth/status` to keep the registry descriptor uniform.

- `packages/core/src/qwen/qwenOAuth2.ts`:
  - exports `cacheQwenCredentials` (was a private function; needed
    by the daemon's device-flow registry)
  - `cacheQwenCredentials` now calls `SharedTokenManager.clearCache()`
    after writing, folding what was previously a paired call site at
    L820+L829. Idempotent change.
  - file mode `0o600` on `oauth_creds.json` (was default 0o666 +
    umask). Mirrors opencode's `auth/index.ts`.
- `packages/cli/src/serve/runQwenServe.ts`: device-flow registry
  `dispose()` wired into the shutdown drain (BEFORE
  `bridge.shutdown()`).

- `auth/deviceFlow.test.ts` — 21 tests: BrandedSecret leak paths,
  state machine (slow_down / success / error), terminal grace,
  concurrent-start coalescing, dispose, cancel idempotency, static-
  source grep against browser-spawn primitives.
- `server.test.ts` — 10 device-flow integration tests:
  POST 201/200 take-over, strict 401, 400 `unsupported_provider`,
  GET / DELETE / `/workspace/auth/status`, 502 `upstream_error`
  mapping, sweeper-driven auto-expiry with controlled clock,
  capability advertisement.
- `daemonEvents.test.ts` — 5 SDK reducer tests: type guards, per-
  provider state projection, `failed` always → `status: 'error'`
  (errorKind carries the kind, including new `persist_failed`),
  session reducer no-ops on auth events.

369/369 serve + SDK tests pass; typecheck + `eslint
--max-warnings 0` clean across 14 PR 21 files.

- [x] Independently mergeable (depends only on merged PR 4 / PR 7 /
      PR 12 / PR 15)
- [x] Backward compatible (4 new routes + 1 capability tag + 5 typed
      events + 4 SDK helpers; existing routes/events untouched)
- [x] Default off (capability advertised but no client is forced to
      use it; CLI `qwen` OAuth flow unchanged)
- [x] `qwen serve` Stage 1 routes / SDK behavior preserved
- [x] Gradual migration (v1 only `qwen-oauth`; future providers
      register through the `DeviceFlowProvider` interface)
- [x] Reversible (revert removes 4 routes + 1 tag + 5 events with no
      schema migration)
- [x] Tests-first (28 new tests across 3 layers)

- Inline `bridge.broadcastWorkspaceEvent` → fold-in to PR 16 (#4249)
  `publishWorkspaceEvent` once that lands
- `/workspace/auth/status` vs PR 12 `/workspace/providers` boundary
  — separate route in v1; merge alternative discussed
- Wave 4 PRs 17/19/20 should adopt the same mutate-strict +
  workspace event-fan-out pattern

5 items from pre-PR specialist passes parked for a focused
follow-up: `DeviceFlowEntry` discriminated union, single-source SDK
status / ProviderId unions, `awaitCompletion` memoization,
broadcast-100%-fail stderr elevation, SDK 404 →
`not_found_or_evicted` errorKind.

Refs: #4175

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

Twelve correctness + structural fixes from a wenshao + DeepSeek + gpt-5.5
review pass. Tests deferred to fold-in 10 (separate, larger commit).

CRITICAL CORRECTNESS

#7 — `provider.persist()` Promise.race could publish `persist_failed`
to SSE while a non-cooperative provider was still committing
credentials to disk. Added an independent tracker on the original
persist promise: if the race timed out (`persistTimedOut === true`)
AND the underlying persist later resolved successfully, audit a
`lost_success_after_timeout` breadcrumb so operators see the
inconsistency. Tightened the persist `@remarks` contract to require
signal honoring end-to-end. Qwen provider already complies (fold-in
3 #10); this is forward-defense for future providers.

#11 — auth surface (`DaemonAuthFlow`, `reduceDaemonAuthEvent`,
`createDaemonAuthState`, `DEVICE_FLOW_EXPIRY_GRACE_MS`, all event /
data / state types) was re-exported from `src/daemon/index.ts` but
NEVER from the published SDK entry `src/index.ts`. SDK consumers got
`undefined` for everything except `client.auth.start()` (which
traveled through the already-exported `DaemonClient`). Added the
missing exports and pinned via `daemon-public-surface.test.ts`.

#12 — `core/src/qwen/qwenOAuth2.ts:373`'s
`debugLogger.debug('Device authorization result:', result)` writes
the raw `device_code` (RFC 8628 bearer-equivalent credential) to
stderr / journald, bypassing the `BrandedSecret` redaction layer.
Pre-existing on main but PR 21 expanded the exposure surface.
Sanitized to log only `{ ok, expires_in }` on success / `{ ok,
error }` on error.

#13 — `runPollTick` success-branch persist-failure × past-`expiresAt`
classified as `expired_token` instead of `persist_failed`, routing
operators toward "tell user to retry" (RFC 8628 expiry) when the
actual root cause was disk I/O. Reclassified to `persist_failed`
with a `persist_also_failed_past_expiry` audit hint to preserve the
timing detail for incident response.

SMALL CORRECTNESS

#1 — `runPollTick` catch hint replaced with a STATIC bounded message
("provider.poll() failed; see daemon audit log for details"). The
fold-in 8 truncated-prefix approach could still leak the first 256
chars of provider-templated raw text including secret material. Full
raw still routed to audit channel for operator visibility.

#5 — `cancellerClientId` field added to `DeviceFlowEntry`; deferred-
cancel branch in `cancel()` now stamps it on the entry, and the
persist-resolution `cancelled` event publish uses
`entry.cancellerClientId ?? entry.initiatorClientId`. SSE consumers
that suppress self-emitted events can now attribute the cancel
correctly.

#6 — `AwaitCompletionOptions.timeoutMs === 0` (the documented
"settle immediately, return current daemon view" contract) was
treated as falsy by the `?` ternary, falling back to the default.
`sanitizePositiveMs` now takes an `allowZero` opt-in; the ceiling
computation uses `!== undefined` instead of truthy check.

#8 — `EventBus.publish()` returns `undefined` for closed buses (it
does NOT throw). `broadcastWorkspaceEvent` previously counted that
path as success, hiding the all-buses-dropped operator alarm.
Folded the closed-bus-as-failure check into the canonical
`publishWorkspaceEvent` (see #X below).

#9 — start-timeout Promise.race rejected with a plain `Error`,
falling through `sendBridgeError` to a generic 500. Switched to
`UpstreamDeviceFlowError` so a hung IdP correctly surfaces as 502
(matching the envelope every other IdP start failure uses).

STRUCTURAL

#3 — Three identical `transitionTerminal + publish + audit`
expired_token blocks in `runPollTick`/`sweep`/(removed by #13)
deduplicated into a private `expireEntry()` helper. Future event-
shape changes are now a one-edit operation.

#X — PR 16 (#4249) merged on 2026-05-18 06:27Z. Per the inline
comment at httpAcpBridge.ts:501, PR 21's `broadcastWorkspaceEvent`
was kept distinct only to avoid the merge conflict; once PR 16
landed, it became a fold-in candidate. Folded the closed-bus +
all-failed-stderr-escalation operator-visibility features (PR 21's
S5 + fold-in 9 #8) INTO `publishWorkspaceEvent`; dropped
`broadcastWorkspaceEvent` from the bridge interface + impl + test
mocks. PR 21's deviceFlowEventSink now calls
`bridge.publishWorkspaceEvent` — single canonical workspace fan-out.

DOC

#16 — Added a "Cross-client take-over" paragraph to
`docs/users/qwen-serve.md` explaining that two clients on the same
daemon for the same provider get the per-provider singleton with
`attached: true`/`false` distinguishing them; no separate event
fires (both eventually observe the same `auth_device_flow_authorized`).

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

Implements issue #4175 Wave 4 PR 21. Brokers OAuth 2.0 Device
Authorization Grant (RFC 8628) through the `qwen serve` daemon so a
remote SDK client can trigger a Qwen-account login whose tokens land
on the **daemon** filesystem, not on the client. The daemon polls the
IdP itself; the client's only job is to display the verification URL +
user code.

Runtime locality (#4175 §11): the daemon NEVER spawns a browser or
calls `open(url)` — even when running locally. Static-source grep
test fails the build on `node:child_process` / `open` / `xdg-open` /
`shell.openExternal` / `execa` / `shelljs` / `process.spawn` and
their dynamic-import / require variants.

- `POST /workspace/auth/device-flow` — strict mutation gate; returns
  201 fresh / 200 idempotent take-over with `attached: true`. Per
  per-`providerId` singleton: a second POST while pending takes over
  rather than allocating a new `device_code`.
- `GET /workspace/auth/device-flow/:id` — public state read. Pending
  entries echo `userCode/verificationUri/expiresAt/intervalMs`;
  terminal entries (5-min grace) drop them and surface
  `status/errorKind/hint`.
- `DELETE /workspace/auth/device-flow/:id` — strict; idempotent
  (terminal → 204 no-op; unknown → 404).
- `GET /workspace/auth/status` — pending flows + supported providers
  snapshot. v1 stub for `providers: []` (populated in fold-in 1).

`DeviceFlowRegistry` (`packages/cli/src/serve/auth/deviceFlow.ts`)
is the in-memory state holder:
- per-`providerId` singleton with idempotent take-over
- workspace-wide cap of 4 active flows (abuse defense)
- 5-min terminal grace so SDK reconnects can still observe results
- TTL sweeper evicts grace-expired entries every 30s
- in-flight `Promise` map coalesces concurrent `start()` calls so two
  parallel POSTs don't double-allocate IdP `device_code`
- `transitionTerminal` returns `boolean` so caller-side emit/audit
  guard prevents sweeper × poll-tick double-fire
- `dispose()` wired into `runQwenServe.close()`'s shutdown drain;
  cancels `provider.poll()` mid-flight via `cancelController`,
  records `lost_success` audit when an IdP-minted token is dropped
  by transition

`DeviceFlowProvider` interface accepts `start({signal})` +
`poll(state, {signal})`. `QwenOAuthDeviceFlowProvider` wraps the
existing `QwenOAuth2Client.requestDeviceAuthorization` /
`pollDeviceToken` primitives directly (NOT
`authWithQwenDeviceFlow`, which calls `open(url)`). PKCE is
provider-required by Qwen but optional in the interface for future
non-PKCE providers. `success.persist()` writes to disk FIRST, then
updates the in-process client — a failed disk write no longer
leaves the daemon with a zombie in-memory token. Maps RFC 8628
errors via an anchored regex (`^Device token poll failed:
(expired_token|access_denied|invalid_grant)`) so an
`error_description` containing one of those literals can't
mis-classify an unrelated upstream error.

`BrandedSecret<T extends string>` holds the `device_code` and PKCE
verifier. Earlier draft used `new String()` wrapper which leaked
through `+` / template literals (`Symbol.toPrimitive` →
`valueOf` returned the primitive). Final shape: frozen plain object
+ `WeakMap` indirection + 4-way redaction
(`toString` / `toJSON` / `Symbol.toPrimitive` / numeric coercion →
`'[redacted]'` or `NaN`) + `unique symbol` brand. 6 leak-path
tests: `JSON.stringify` / `String()` / concat / template / `+x` /
reveal-roundtrip.

5 new daemon events (workspace-scoped, fanned out to every active
session bus via `bridge.broadcastWorkspaceEvent`):

- `auth_device_flow_started` — `{deviceFlowId, providerId, expiresAt}`
  (no userCode/verificationUri — see PR 21 design §3)
- `auth_device_flow_throttled` — `{deviceFlowId, intervalMs}`,
  emitted only on upstream `slow_down` interval bumps
- `auth_device_flow_authorized` — `{deviceFlowId, providerId,
  expiresAt?, accountAlias?}`; `accountAlias` is best-effort
  non-PII (never email/phone)
- `auth_device_flow_failed` — `{deviceFlowId, errorKind, hint?}`
  with `errorKind ∈ {expired_token, access_denied, invalid_grant,
  upstream_error, persist_failed}`
- `auth_device_flow_cancelled` — `{deviceFlowId}` (DELETE on pending)

Workspace-scoped reducer `reduceDaemonAuthEvent` produces
`DaemonAuthState { flows: Partial<Record<ProviderId, ...>> }` —
parallel to `reduceDaemonSessionEvent`. Session reducer no-ops on
auth events (workspace-scoped state belongs in its own reducer).

`bridge.broadcastWorkspaceEvent` is intentionally distinct from PR
16's `publishWorkspaceEvent` to avoid merge conflict; collapses to
the shared helper as a fold-in once #4249 lands (~25 LoC).

`@qwen-code/sdk` (`packages/sdk-typescript/`):

- 4 new `DaemonClient` methods: `startDeviceFlow`, `getDeviceFlow`,
  `cancelDeviceFlow`, `getAuthStatus` — typed against the wire
  shapes, errors mapped through the existing `DaemonHttpError`.
- High-level `client.auth` getter (lazy `DaemonAuthFlow` singleton)
  exposes a `start(...).awaitCompletion()` shape mirroring `gh auth
  login`'s UX: print code first, let the SDK consumer decide where
  to open the browser. `awaitCompletion` polls GET on the
  daemon-supplied `intervalMs`, honors `slow_down` bumps, and
  fall-back-recovers from 404 (entry evicted post-grace).

POST + DELETE flow through PR 15's `mutate({strict: true})` —
401 `token_required` on token-less loopback defaults. GET routes
use only the global `bearerAuth`. Every state transition
(`started/authorized/failed/cancelled/expired/lost_success`)
records a structured stderr breadcrumb (`[serve] auth.device-flow:
provider=... deviceFlowId=abc12... clientId=... status=...`)
since `mutate()` doesn't carry an audit hook — events alone aren't
enough since SDK can silently drop them; stderr → journald/docker
logs is the unfalsifiable record.

`auth_device_flow` advertised unconditionally on
`/capabilities.features`. Supported providers list lives on
`/workspace/auth/status` to keep the registry descriptor uniform.

- `packages/core/src/qwen/qwenOAuth2.ts`:
  - exports `cacheQwenCredentials` (was a private function; needed
    by the daemon's device-flow registry)
  - `cacheQwenCredentials` now calls `SharedTokenManager.clearCache()`
    after writing, folding what was previously a paired call site at
    L820+L829. Idempotent change.
  - file mode `0o600` on `oauth_creds.json` (was default 0o666 +
    umask). Mirrors opencode's `auth/index.ts`.
- `packages/cli/src/serve/runQwenServe.ts`: device-flow registry
  `dispose()` wired into the shutdown drain (BEFORE
  `bridge.shutdown()`).

- `auth/deviceFlow.test.ts` — 21 tests: BrandedSecret leak paths,
  state machine (slow_down / success / error), terminal grace,
  concurrent-start coalescing, dispose, cancel idempotency, static-
  source grep against browser-spawn primitives.
- `server.test.ts` — 10 device-flow integration tests:
  POST 201/200 take-over, strict 401, 400 `unsupported_provider`,
  GET / DELETE / `/workspace/auth/status`, 502 `upstream_error`
  mapping, sweeper-driven auto-expiry with controlled clock,
  capability advertisement.
- `daemonEvents.test.ts` — 5 SDK reducer tests: type guards, per-
  provider state projection, `failed` always → `status: 'error'`
  (errorKind carries the kind, including new `persist_failed`),
  session reducer no-ops on auth events.

369/369 serve + SDK tests pass; typecheck + `eslint
--max-warnings 0` clean across 14 PR 21 files.

- [x] Independently mergeable (depends only on merged PR 4 / PR 7 /
      PR 12 / PR 15)
- [x] Backward compatible (4 new routes + 1 capability tag + 5 typed
      events + 4 SDK helpers; existing routes/events untouched)
- [x] Default off (capability advertised but no client is forced to
      use it; CLI `qwen` OAuth flow unchanged)
- [x] `qwen serve` Stage 1 routes / SDK behavior preserved
- [x] Gradual migration (v1 only `qwen-oauth`; future providers
      register through the `DeviceFlowProvider` interface)
- [x] Reversible (revert removes 4 routes + 1 tag + 5 events with no
      schema migration)
- [x] Tests-first (28 new tests across 3 layers)

- Inline `bridge.broadcastWorkspaceEvent` → fold-in to PR 16 (#4249)
  `publishWorkspaceEvent` once that lands
- `/workspace/auth/status` vs PR 12 `/workspace/providers` boundary
  — separate route in v1; merge alternative discussed
- Wave 4 PRs 17/19/20 should adopt the same mutate-strict +
  workspace event-fan-out pattern

5 items from pre-PR specialist passes parked for a focused
follow-up: `DeviceFlowEntry` discriminated union, single-source SDK
status / ProviderId unions, `awaitCompletion` memoization,
broadcast-100%-fail stderr elevation, SDK 404 →
`not_found_or_evicted` errorKind.

Refs: #4175

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

Twelve correctness + structural fixes from a wenshao + DeepSeek + gpt-5.5
review pass. Tests deferred to fold-in 10 (separate, larger commit).

CRITICAL CORRECTNESS

#7 — `provider.persist()` Promise.race could publish `persist_failed`
to SSE while a non-cooperative provider was still committing
credentials to disk. Added an independent tracker on the original
persist promise: if the race timed out (`persistTimedOut === true`)
AND the underlying persist later resolved successfully, audit a
`lost_success_after_timeout` breadcrumb so operators see the
inconsistency. Tightened the persist `@remarks` contract to require
signal honoring end-to-end. Qwen provider already complies (fold-in
3 #10); this is forward-defense for future providers.

#11 — auth surface (`DaemonAuthFlow`, `reduceDaemonAuthEvent`,
`createDaemonAuthState`, `DEVICE_FLOW_EXPIRY_GRACE_MS`, all event /
data / state types) was re-exported from `src/daemon/index.ts` but
NEVER from the published SDK entry `src/index.ts`. SDK consumers got
`undefined` for everything except `client.auth.start()` (which
traveled through the already-exported `DaemonClient`). Added the
missing exports and pinned via `daemon-public-surface.test.ts`.

#12 — `core/src/qwen/qwenOAuth2.ts:373`'s
`debugLogger.debug('Device authorization result:', result)` writes
the raw `device_code` (RFC 8628 bearer-equivalent credential) to
stderr / journald, bypassing the `BrandedSecret` redaction layer.
Pre-existing on main but PR 21 expanded the exposure surface.
Sanitized to log only `{ ok, expires_in }` on success / `{ ok,
error }` on error.

#13 — `runPollTick` success-branch persist-failure × past-`expiresAt`
classified as `expired_token` instead of `persist_failed`, routing
operators toward "tell user to retry" (RFC 8628 expiry) when the
actual root cause was disk I/O. Reclassified to `persist_failed`
with a `persist_also_failed_past_expiry` audit hint to preserve the
timing detail for incident response.

SMALL CORRECTNESS

#1 — `runPollTick` catch hint replaced with a STATIC bounded message
("provider.poll() failed; see daemon audit log for details"). The
fold-in 8 truncated-prefix approach could still leak the first 256
chars of provider-templated raw text including secret material. Full
raw still routed to audit channel for operator visibility.

#5 — `cancellerClientId` field added to `DeviceFlowEntry`; deferred-
cancel branch in `cancel()` now stamps it on the entry, and the
persist-resolution `cancelled` event publish uses
`entry.cancellerClientId ?? entry.initiatorClientId`. SSE consumers
that suppress self-emitted events can now attribute the cancel
correctly.

#6 — `AwaitCompletionOptions.timeoutMs === 0` (the documented
"settle immediately, return current daemon view" contract) was
treated as falsy by the `?` ternary, falling back to the default.
`sanitizePositiveMs` now takes an `allowZero` opt-in; the ceiling
computation uses `!== undefined` instead of truthy check.

#8 — `EventBus.publish()` returns `undefined` for closed buses (it
does NOT throw). `broadcastWorkspaceEvent` previously counted that
path as success, hiding the all-buses-dropped operator alarm.
Folded the closed-bus-as-failure check into the canonical
`publishWorkspaceEvent` (see #X below).

#9 — start-timeout Promise.race rejected with a plain `Error`,
falling through `sendBridgeError` to a generic 500. Switched to
`UpstreamDeviceFlowError` so a hung IdP correctly surfaces as 502
(matching the envelope every other IdP start failure uses).

STRUCTURAL

#3 — Three identical `transitionTerminal + publish + audit`
expired_token blocks in `runPollTick`/`sweep`/(removed by #13)
deduplicated into a private `expireEntry()` helper. Future event-
shape changes are now a one-edit operation.

#X — PR 16 (#4249) merged on 2026-05-18 06:27Z. Per the inline
comment at httpAcpBridge.ts:501, PR 21's `broadcastWorkspaceEvent`
was kept distinct only to avoid the merge conflict; once PR 16
landed, it became a fold-in candidate. Folded the closed-bus +
all-failed-stderr-escalation operator-visibility features (PR 21's
S5 + fold-in 9 #8) INTO `publishWorkspaceEvent`; dropped
`broadcastWorkspaceEvent` from the bridge interface + impl + test
mocks. PR 21's deviceFlowEventSink now calls
`bridge.publishWorkspaceEvent` — single canonical workspace fan-out.

DOC

#16 — Added a "Cross-client take-over" paragraph to
`docs/users/qwen-serve.md` explaining that two clients on the same
daemon for the same provider get the per-provider singleton with
`attached: true`/`false` distinguishing them; no separate event
fires (both eventually observe the same `auth_device_flow_authorized`).

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

PRs #4249 (workspace memory + agents CRUD) and #4269 (workspace file
read routes) added `workspace_memory`, `workspace_agents`, and
`workspace_file_read` to `SERVE_CAPABILITY_REGISTRY` and updated the
unit-level `EXPECTED_STAGE1_FEATURES` in
`packages/cli/src/serve/server.test.ts`, but missed the matching
integration-test expectation. The E2E `qwen serve — capabilities
envelope > advertises all baseline capabilities` assertion has been
failing on `main` since those PRs landed.

Append the three tags in the same positions as
`SERVE_CAPABILITY_REGISTRY` and the unit-level constant
(`workspace_memory` + `workspace_agents` after `workspace_providers`,
`workspace_file_read` after `mcp_guardrails`). No production code
changes — same shape as #4268.

* feat(serve): auth device-flow route

Implements issue #4175 Wave 4 PR 21. Brokers OAuth 2.0 Device
Authorization Grant (RFC 8628) through the `qwen serve` daemon so a
remote SDK client can trigger a Qwen-account login whose tokens land
on the **daemon** filesystem, not on the client. The daemon polls the
IdP itself; the client's only job is to display the verification URL +
user code.

Runtime locality (#4175 §11): the daemon NEVER spawns a browser or
calls `open(url)` — even when running locally. Static-source grep
test fails the build on `node:child_process` / `open` / `xdg-open` /
`shell.openExternal` / `execa` / `shelljs` / `process.spawn` and
their dynamic-import / require variants.

- `POST /workspace/auth/device-flow` — strict mutation gate; returns
  201 fresh / 200 idempotent take-over with `attached: true`. Per
  per-`providerId` singleton: a second POST while pending takes over
  rather than allocating a new `device_code`.
- `GET /workspace/auth/device-flow/:id` — public state read. Pending
  entries echo `userCode/verificationUri/expiresAt/intervalMs`;
  terminal entries (5-min grace) drop them and surface
  `status/errorKind/hint`.
- `DELETE /workspace/auth/device-flow/:id` — strict; idempotent
  (terminal → 204 no-op; unknown → 404).
- `GET /workspace/auth/status` — pending flows + supported providers
  snapshot. v1 stub for `providers: []` (populated in fold-in 1).

`DeviceFlowRegistry` (`packages/cli/src/serve/auth/deviceFlow.ts`)
is the in-memory state holder:
- per-`providerId` singleton with idempotent take-over
- workspace-wide cap of 4 active flows (abuse defense)
- 5-min terminal grace so SDK reconnects can still observe results
- TTL sweeper evicts grace-expired entries every 30s
- in-flight `Promise` map coalesces concurrent `start()` calls so two
  parallel POSTs don't double-allocate IdP `device_code`
- `transitionTerminal` returns `boolean` so caller-side emit/audit
  guard prevents sweeper × poll-tick double-fire
- `dispose()` wired into `runQwenServe.close()`'s shutdown drain;
  cancels `provider.poll()` mid-flight via `cancelController`,
  records `lost_success` audit when an IdP-minted token is dropped
  by transition

`DeviceFlowProvider` interface accepts `start({signal})` +
`poll(state, {signal})`. `QwenOAuthDeviceFlowProvider` wraps the
existing `QwenOAuth2Client.requestDeviceAuthorization` /
`pollDeviceToken` primitives directly (NOT
`authWithQwenDeviceFlow`, which calls `open(url)`). PKCE is
provider-required by Qwen but optional in the interface for future
non-PKCE providers. `success.persist()` writes to disk FIRST, then
updates the in-process client — a failed disk write no longer
leaves the daemon with a zombie in-memory token. Maps RFC 8628
errors via an anchored regex (`^Device token poll failed:
(expired_token|access_denied|invalid_grant)`) so an
`error_description` containing one of those literals can't
mis-classify an unrelated upstream error.

`BrandedSecret<T extends string>` holds the `device_code` and PKCE
verifier. Earlier draft used `new String()` wrapper which leaked
through `+` / template literals (`Symbol.toPrimitive` →
`valueOf` returned the primitive). Final shape: frozen plain object
+ `WeakMap` indirection + 4-way redaction
(`toString` / `toJSON` / `Symbol.toPrimitive` / numeric coercion →
`'[redacted]'` or `NaN`) + `unique symbol` brand. 6 leak-path
tests: `JSON.stringify` / `String()` / concat / template / `+x` /
reveal-roundtrip.

5 new daemon events (workspace-scoped, fanned out to every active
session bus via `bridge.broadcastWorkspaceEvent`):

- `auth_device_flow_started` — `{deviceFlowId, providerId, expiresAt}`
  (no userCode/verificationUri — see PR 21 design §3)
- `auth_device_flow_throttled` — `{deviceFlowId, intervalMs}`,
  emitted only on upstream `slow_down` interval bumps
- `auth_device_flow_authorized` — `{deviceFlowId, providerId,
  expiresAt?, accountAlias?}`; `accountAlias` is best-effort
  non-PII (never email/phone)
- `auth_device_flow_failed` — `{deviceFlowId, errorKind, hint?}`
  with `errorKind ∈ {expired_token, access_denied, invalid_grant,
  upstream_error, persist_failed}`
- `auth_device_flow_cancelled` — `{deviceFlowId}` (DELETE on pending)

Workspace-scoped reducer `reduceDaemonAuthEvent` produces
`DaemonAuthState { flows: Partial<Record<ProviderId, ...>> }` —
parallel to `reduceDaemonSessionEvent`. Session reducer no-ops on
auth events (workspace-scoped state belongs in its own reducer).

`bridge.broadcastWorkspaceEvent` is intentionally distinct from PR
16's `publishWorkspaceEvent` to avoid merge conflict; collapses to
the shared helper as a fold-in once #4249 lands (~25 LoC).

`@qwen-code/sdk` (`packages/sdk-typescript/`):

- 4 new `DaemonClient` methods: `startDeviceFlow`, `getDeviceFlow`,
  `cancelDeviceFlow`, `getAuthStatus` — typed against the wire
  shapes, errors mapped through the existing `DaemonHttpError`.
- High-level `client.auth` getter (lazy `DaemonAuthFlow` singleton)
  exposes a `start(...).awaitCompletion()` shape mirroring `gh auth
  login`'s UX: print code first, let the SDK consumer decide where
  to open the browser. `awaitCompletion` polls GET on the
  daemon-supplied `intervalMs`, honors `slow_down` bumps, and
  fall-back-recovers from 404 (entry evicted post-grace).

POST + DELETE flow through PR 15's `mutate({strict: true})` —
401 `token_required` on token-less loopback defaults. GET routes
use only the global `bearerAuth`. Every state transition
(`started/authorized/failed/cancelled/expired/lost_success`)
records a structured stderr breadcrumb (`[serve] auth.device-flow:
provider=... deviceFlowId=abc12... clientId=... status=...`)
since `mutate()` doesn't carry an audit hook — events alone aren't
enough since SDK can silently drop them; stderr → journald/docker
logs is the unfalsifiable record.

`auth_device_flow` advertised unconditionally on
`/capabilities.features`. Supported providers list lives on
`/workspace/auth/status` to keep the registry descriptor uniform.

- `packages/core/src/qwen/qwenOAuth2.ts`:
  - exports `cacheQwenCredentials` (was a private function; needed
    by the daemon's device-flow registry)
  - `cacheQwenCredentials` now calls `SharedTokenManager.clearCache()`
    after writing, folding what was previously a paired call site at
    L820+L829. Idempotent change.
  - file mode `0o600` on `oauth_creds.json` (was default 0o666 +
    umask). Mirrors opencode's `auth/index.ts`.
- `packages/cli/src/serve/runQwenServe.ts`: device-flow registry
  `dispose()` wired into the shutdown drain (BEFORE
  `bridge.shutdown()`).

- `auth/deviceFlow.test.ts` — 21 tests: BrandedSecret leak paths,
  state machine (slow_down / success / error), terminal grace,
  concurrent-start coalescing, dispose, cancel idempotency, static-
  source grep against browser-spawn primitives.
- `server.test.ts` — 10 device-flow integration tests:
  POST 201/200 take-over, strict 401, 400 `unsupported_provider`,
  GET / DELETE / `/workspace/auth/status`, 502 `upstream_error`
  mapping, sweeper-driven auto-expiry with controlled clock,
  capability advertisement.
- `daemonEvents.test.ts` — 5 SDK reducer tests: type guards, per-
  provider state projection, `failed` always → `status: 'error'`
  (errorKind carries the kind, including new `persist_failed`),
  session reducer no-ops on auth events.

369/369 serve + SDK tests pass; typecheck + `eslint
--max-warnings 0` clean across 14 PR 21 files.

- [x] Independently mergeable (depends only on merged PR 4 / PR 7 /
      PR 12 / PR 15)
- [x] Backward compatible (4 new routes + 1 capability tag + 5 typed
      events + 4 SDK helpers; existing routes/events untouched)
- [x] Default off (capability advertised but no client is forced to
      use it; CLI `qwen` OAuth flow unchanged)
- [x] `qwen serve` Stage 1 routes / SDK behavior preserved
- [x] Gradual migration (v1 only `qwen-oauth`; future providers
      register through the `DeviceFlowProvider` interface)
- [x] Reversible (revert removes 4 routes + 1 tag + 5 events with no
      schema migration)
- [x] Tests-first (28 new tests across 3 layers)

- Inline `bridge.broadcastWorkspaceEvent` → fold-in to PR 16 (#4249)
  `publishWorkspaceEvent` once that lands
- `/workspace/auth/status` vs PR 12 `/workspace/providers` boundary
  — separate route in v1; merge alternative discussed
- Wave 4 PRs 17/19/20 should adopt the same mutate-strict +
  workspace event-fan-out pattern

5 items from pre-PR specialist passes parked for a focused
follow-up: `DeviceFlowEntry` discriminated union, single-source SDK
status / ProviderId unions, `awaitCompletion` memoization,
broadcast-100%-fail stderr elevation, SDK 404 →
`not_found_or_evicted` errorKind.

Refs: #4175

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

* fixup(serve): address PR #4255 round-1 review feedback

Eleven items from copilot-pull-request-reviewer's round-1 pass on
#4255 — 4 inline threads + 7 from the PR-level review summary.

## Adopted (11 items, code/doc changes)

- **`lastSeenAt` → `lastSeenEventId`** (`events.ts`,
  `DaemonDeviceFlowReducerState`). The field was set from
  `rawEvent.id` (SSE event id) but documented as "epoch ms" — a real
  semantic mismatch that would mislead consumers into time-based
  logic against a monotonic counter. Rename + tighten the JSDoc to
  describe it as an event-id counter; reducer cases updated.
- **`DEVICE_FLOW_EXPIRY_GRACE_MS = 30_000` extracted** in
  `DaemonAuthFlow.ts` (was a magic number on `start.expiresAt +
  30_000`). `AwaitCompletionOptions.timeoutMs` doc now describes the
  actual grace-past-expiry behavior + the rationale (clock skew +
  daemon sweeper interval + network latency) instead of the wrong
  "defaults to expiresAt - Date.now()" claim.
- **Explicit `chmod 0o600`** in `cacheQwenCredentials` after every
  write. `fs.writeFile`'s `mode` only applies on file creation; a
  pre-existing `oauth_creds.json` written under a broader umask kept
  its old permissions across upgrades. The chmod now tightens it on
  every write; chmod failure (Windows / hardened FS) surfaces via
  `debugLogger.warn` instead of silently dropping the invariant.
- **`SharedTokenManager.clearCache()` failure now logs**
  `debugLogger.warn` (was a silent `try { } catch { }`). In
  production a swallowed clearCache means in-process callers serve
  stale credentials until the SharedTokenManager mtime watcher
  catches up — a recoverable degradation worth a log line.
- **Protocol doc** lists `persist_failed` in the
  `auth_device_flow_failed.errorKind` union (was added to the type
  but missed in the doc).
- **`pollDeviceToken({signal})`** plumbed through
  `IQwenOAuth2Client` interface + `QwenOAuth2Client` impl + the Qwen
  device-flow provider. Cancel / dispose during a slow IdP response
  now aborts the in-flight HTTP socket immediately instead of
  waiting for the upstream timeout. Two new registry tests assert
  `cancel()` / `dispose()` propagate abort to the signal observed by
  `provider.poll`.
- **`revealSecret` error message** clarified: was "secret has been
  GC-evicted" (impossible — WeakMap doesn't evict reachable keys).
  Now points at the actual reachable failure modes (forged shape /
  serialize+reparse losing the WeakMap binding).
- **`transitionTerminal` JSDoc** clarifies that the PRIMARY guard
  against late timer secret leaks is the `entry.status !== 'pending'`
  check at the top of `runPollTick`; secret-clearing here is
  defense-in-depth.
- **`DeviceFlowErrorKind` JSDoc'd per variant** so consumers can tell
  when each fires (RFC 8628 distinctions + `persist_failed` vs
  `upstream_error` boundary).
- **Stale "PR 16 / PR 21 §3" temporal references** in
  `DaemonAuthFlow.ts:124` rephrased to be timeless ("workspace-scoped
  events fan out through whatever session buses happen to be live"
  — no PR number references that rot when those PRs merge).

## Not adopted (4 items, replied to in-thread)

- **`authWithQwenDeviceFlow` browser-launch separation** — correct
  architectural advice but out of #4255 scope (would refactor a CLI
  auth UX module that PR 21 only touched additively). Tracked as a
  Wave 5 follow-up.
- **Copyright header year range** — repo-wide convention "2025"; not
  introduced by this PR.
- **Spread `...(x ? {x} : {})` → `x: x ?? undefined`** — the two are
  not semantically equivalent. The current form omits the key
  entirely on falsy `x`; the suggested form always includes the key.
  Tests assert object shape and would break under the change.
- **Eager `client.auth` getter** — public API boundary. Lazy
  construction matches `DaemonSessionClient` precedent + saves the
  module load for SDK consumers that never touch auth.

Refs: #4175 #4255

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

* fixup(serve): address PR #4255 wenshao round-1 review feedback

15 items from @wenshao's review batches on #4255. Catches a handful
of real bugs that the earlier round (commit 3d9f082f5) didn't
surface.

## Critical fixes

- **C1 — `pollUntilTerminal` providerId pass-through**
  (`DaemonAuthFlow.ts:185`). The synthetic 404 fallback hardcoded
  `providerId: 'qwen-oauth'`; the parent `awaitCompletion` already
  receives the real providerId via `start.providerId` but
  `pollUntilTerminal`'s parameter type stripped it. Add the field to
  the param type, propagate.
- **C2 — open `errorKind` allowlist** (`events.ts`). The closed
  5-value union in the type guard silently dropped any `failed`
  event whose errorKind the daemon added without mirroring SDK-side
  (e.g. a future `rate_limited`). The flow's reducer state would
  never transition to terminal, leaving SDK consumers stuck on
  `pending` forever. Open the union with `(string & {})` and accept
  any non-empty string in the runtime guard. Updated test asserts
  forward-compat behavior + still rejects the truly-malformed
  empty-string case.
- **C3 — `persist()` timeout + signal**
  (`deviceFlow.ts`). A wedged disk I/O (NFS stall, encrypted-volume
  contention) without bounds would pin the entry in `pending` until
  the upstream `expires_in` elapsed (potentially minutes). The
  registry now passes its `cancelController.signal` AND arms a hard
  `DEVICE_FLOW_PERSIST_TIMEOUT_MS = 30_000` timer; persist failure
  surfaces as `persist_failed` immediately. The
  `DeviceFlowPollResult` `success` variant signature changed to
  `persist({signal})`.
- **C4 — cancel × success race rollback**
  (`deviceFlow.ts` + Qwen provider). Today, if `cancel()`
  transitions while `persist()` is in flight, the credentials get
  written but the flow's status is `cancelled`. User sees cancelled,
  daemon disk has a valid token. `DeviceFlowPollResult.success`
  gains an optional `unpersist()` callback the registry calls when
  `transitionTerminal(authorized)` fails — the Qwen provider wires
  it to `clearQwenCredentials()`. Rollback failure is audited but
  not propagated (re-running auth would overwrite anyway).
- **C5 — don't `unref()` the `awaitCompletion` sleep timer**
  (`DaemonAuthFlow.ts`). On a standalone Node CLI/script doing just
  `client.auth.start().awaitCompletion()`, the unref'd between-poll
  timer was the only event-loop handle, so Node could exit before
  the user finished authorization. The poll wait is foreground work
  the caller explicitly awaits — keep it ref'd.

## Information-leak fixes

- **S1 — sanitize `persist_failed` hint**. `err.message` from
  `cacheQwenCredentials` embeds the full `~/.qwen/oauth_creds.json`
  path. Broadcast via SSE, that path leaks the daemon's home layout
  to every connected session subscriber. Replace user-facing hint
  with `"credentials could not be written to the daemon filesystem
  — check disk space and permissions"`; full err goes to stderr
  audit only.
- **S2 — sanitize upstream `pollDeviceToken` hint**. The class
  embedded the entire raw IdP response body (which can be an HTML
  error page from a reverse proxy) into the thrown message. Same
  broadcast leak path. Replace upstream-error hint with
  `"unexpected response from identity provider"`; RFC 8628 errors
  use `"Qwen IdP returned ${kind}"`.

## Cleanup / forward-compat

- **D1 — drop duplicate `clearCache()`** at `qwenOAuth2.ts:840`. The
  paired call became redundant once `cacheQwenCredentials` folded
  the clearCache in (PR #4255 fold-in 1). The fold-in 1 message
  said this would be done; the duplicate slipped through.
- **S3 — drop unused `DeviceFlowNotFoundError`** (`deviceFlow.ts`).
  Exported but never imported; route handlers do inline 404 JSON.
- **S4 — single-source SDK status / errorKind unions**
  (`types.ts`). `DaemonAuthDeviceFlowSdkStatus` /
  `DaemonAuthDeviceFlowSdkErrorKind` were parallel literal copies
  of the canonical events.ts definitions — drift waiting to happen.
  Now imported + aliased as type-only re-exports.
- **S5 — broadcast 100% fail elevates to stderr**
  (`httpAcpBridge.ts`). Per-session bus failures stay debug-only,
  but a broadcast where EVERY session bus refused is operationally
  interesting (clients won't see the event). Track success / fail
  counts; `writeStderrLine` when `successCount === 0`.
- **S6 — `this.disposed` check after `await provider.start()`**
  (`deviceFlow.ts`). `dispose()` mid-start would orphan the freshly-
  inserted entry (`schedulePoll` guards on `disposed` so no poll
  fires; the entry never transitions). Throw post-await if disposed.
- **W1 — thread `signal` into `requestDeviceAuthorization`**
  (`qwenOAuth2.ts` + Qwen provider). `start()` had the same
  cancellation gap that `pollDeviceToken` had — a slow
  device-authorization request couldn't be aborted during shutdown.
  Now plumbed end-to-end.
- **W2 — split `invalid_request` from `unsupported_provider`**
  (`server.ts`). Conflating them surfaced misleading remediation
  hints to SDK consumers branching on `code` ("this provider isn't
  supported here" when the real cause was a serializer dropping the
  field). Bad-shape now returns `code: 'invalid_request'`;
  unknown-but-well-formed stays `unsupported_provider`.
- **W3 — drop never-populated `accountAlias`**
  (Qwen provider). The field was wired through types / events /
  reducer / audit but the Qwen IdP's token response doesn't carry
  one (no `name` / `email` / `sub`). Returning only `{expiresAt}`
  makes the field type-honestly absent rather than always-undefined.
  Future provider with an alias-bearing response can populate it.
- **W4 — `DaemonAuthFlow` JSDoc accuracy**. Doc claimed "first
  attempts to consume an SSE event stream … falls back to GET-based
  polling"; actual is GET-only with SSE as a real-time hint for
  clients already subscribed to a session stream.
- **W5 — clearer unit arithmetic** in interval normalization. The
  `(_INTERVAL_MS / 1000) * 1000` cancelation hid the s↔ms boundary;
  expanded form makes both branches unit-explicit.

## Test changes

- `daemonEvents.test.ts` updated to match the now-OPEN errorKind
  union (forward-compat assertion + empty-string still rejected).
- `deviceFlow.test.ts` `FakeProvider.poll` aligned with the new
  `persist({signal})` signature + optional `unpersist`.

## Validation

- `npm run typecheck --workspace packages/cli --workspace
  packages/sdk-typescript --workspace packages/core` — clean
- `npx vitest run packages/cli/src/serve/
  packages/sdk-typescript/test/unit/daemonEvents.test.ts` — 368/368
- `npx eslint --max-warnings 0` over the 11 PR 21 surface files —
  clean

Refs: #4175 #4255

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

* fixup(serve): address PR #4255 wenshao round-2 review feedback

10 new threads from @wenshao's second deep-review pass on #4255.
Verified status: 5 real issues, 1 improvement, 3 stale (already
fixed; comments lagged), 1 false alarm (typecheck demonstrably
clean).

## Critical fixes

- **fold-in 2 C4 REVERSED**: when `provider.poll()` returns success
  AND `cancel()` / `dispose()` transitioned the entry mid-`persist()`,
  the registry now FORCES the entry to `authorized` and keeps the
  on-disk credentials. The earlier rollback (`unpersist()`) wasted
  the user's IdP approval because the RFC 8628 `device_code` is
  single-use — re-running the flow would force them through the
  whole browser-prompt + paste-code dance again for a click whose
  intent was likely "stop the wait" rather than "undo my already-
  completed approval". Aligns with gh CLI / Auth0 SDK / git-
  credential-manager. Audit captures the race via `hint:
  'lost_success_kept ...'`. `DeviceFlowPollResult.success.unpersist`
  field + Qwen provider's `clearQwenCredentials` rollback removed.
- **#1 GET /workspace/auth/device-flow/:id strict gate**: this GET
  surfaces `userCode` / `verificationUri` for pending entries, which
  on the loopback no-token default were readable by any local
  process. POST + DELETE were already strict; aligning GET closes
  the information-disclosure asymmetry. `/workspace/auth/status`
  stays bearer-only (its `pendingDeviceFlows` entries intentionally
  omit `userCode`).
- **#2 `inFlightStarts` hard timeout**: a hung `provider.start()`
  (network partition, unresponsive IdP) used to leave the per-
  `providerId` slot in `inFlightStarts` occupied forever, blocking
  every subsequent POST until daemon restart. New
  `DEVICE_FLOW_START_TIMEOUT_MS = 30_000` arms a timer that
  `cancelController.abort()`s the start; the rejected promise
  unwinds through the `try/finally` clearing the slot.
- **#10 chain-completing the C3 persist-timeout**: the earlier C3
  fix armed a 30s timer that fired `cancelController.abort()` then
  `await result.persist({signal})`, but the chain ended at the
  registry boundary — `cacheQwenCredentials` didn't take a signal,
  so `fs.writeFile` couldn't be aborted. Now `cacheQwenCredentials`
  accepts an optional `{signal}` and threads it into
  `fs.writeFile(..., {signal})` (Node native). The Qwen provider's
  `persist({signal})` forwards the entry's
  `cancelController.signal` end-to-end.

## Improvement (#4): 404 fallback errorKind

`pollUntilTerminal`'s 404 catch used to synthesize
`{status: 'expired'}` for ALL evicted entries — conflating "your
flow expired during your disconnect", "the daemon was restarted",
and "your deviceFlowId was wrong". Now returns
`status: 'error'` + `errorKind: 'not_found_or_evicted'` + a `hint`
so SDK consumers branching on errorKind can distinguish.

## Information leak (#9): start() path raw IdP message

S2 (fold-in 2) sanitized `poll()`'s upstream-error hint, but
`start()` still embedded the raw `err.message` (full IdP response,
potentially HTML from a reverse proxy / WAF) into the
`UpstreamDeviceFlowError` that flowed to SDK clients via the 502.
Now uses static messages for the SDK-visible errors; raw detail
goes through `writeStderrLine` for operator audit only. Mirrors
S2's approach.

## Stale comments cleaned (#5, #7)

`qwenDeviceFlowProvider.ts:177` claimed
`cacheQwenCredentials` "doesn't currently take a signal — that's
a follow-up". After #10 above, that's no longer true; the comment
is replaced with the actual end-to-end signal-threading note.

## Not adopted (1 false alarm)

- Thread on `types.ts:330` claimed type-only-import-after-
  declarations breaks `tsc` and fails `daemonEvents.test.ts:670`
  with TS2345. Demonstrably false: `npx tsc -p
  packages/sdk-typescript/tsconfig.json --noEmit` exits 0;
  `daemonEvents.test.ts` is the post-fold-in-2 file with the
  open-allowlist assertion (test 28/28 passes). The reviewer may
  have been looking at a transient state during their analysis.

## Validation

- `npm run typecheck --workspace packages/cli --workspace
  packages/sdk-typescript --workspace packages/core` — clean
- `npx vitest run packages/cli/src/serve/
  packages/sdk-typescript/test/unit/daemonEvents.test.ts` — 398/398
  pass
- `npx eslint --max-warnings 0` over the PR 21 surface — clean

Refs: #4175 #4255

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

* fixup(serve): address PR #4255 wenshao round-3 review feedback

5 new threads from the third deep-review pass on #4255. 3 real
issues fixed; 1 stale (already done in fold-in 3); 1 deferred as
non-blocking design suggestion.

- **A — `expiresIn` / `interval` non-finite guard**
  (`deviceFlow.ts`). The provider contract types both as `number`,
  but a misbehaving / future provider could hand `undefined` /
  `NaN` / `Infinity`. `Math.max(0, NaN) * 1000` is `NaN`, then
  `now() + NaN` is `NaN`, then `now >= NaN` is always `false` —
  the sweeper would NEVER evict the entry, pinning an upstream
  `device_code` slot until daemon restart. Same hazard on
  `interval * 1000` (NaN → `setTimeout(NaN)` fires immediately,
  Infinity → scheduler clamps to TIMEOUT_MAX). Now both fields go
  through `Number.isFinite(x) && x > 0`; missing/bad values fall
  back to RFC 8628's recommended ceilings (10 min for expiry, 5s
  for interval).

- **D — typed `app.locals` accessor**
  (`deviceFlow.ts` + writer/reader call sites). The
  `app.locals['deviceFlowRegistry']` string key was shared between
  `createServeApp` (writer) and `runQwenServe` (reader); a typo on
  either side would compile cleanly and the shutdown dispose call
  would silently no-op, leaving polling timers running until the
  `unref()` rescue. New `setDeviceFlowRegistry(app, registry)` /
  `getDeviceFlowRegistry(app)` pair gives both call sites
  type-checked access; the string literal is encapsulated in one
  module.

- **E — `UnsupportedDeviceFlowProviderError` docstring**
  (`deviceFlow.ts`). After fold-in 2's W2 fix split
  `invalid_request` from `unsupported_provider`, the route layer
  screens unknown ids against `DEVICE_FLOW_SUPPORTED_PROVIDERS`
  before reaching the registry — so this error is now reachable
  ONLY on a daemon-internal invariant violation (id is declared
  supported but not registered in the runtime provider map).
  Docstring + thrown message updated to reflect that this branch
  signals a programmer error, not user input.

- **B** claimed `cacheQwenCredentials(credentials)` doesn't forward
  signal to `fs.writeFile`. Verified: fold-in 3 (#10) at
  `qwenDeviceFlowProvider.ts:204` calls
  `cacheQwenCredentials(credentials, { signal: persistOpts.signal })`
  and the core helper threads it into `fs.writeFile(..., {mode,
  signal})`. The reviewer was looking at the comment block above
  (lines 174-181) without scrolling to the actual call site.

- **C — SDK `cancelDeviceFlow` lossy 204/404 collapse**.
  Suggested returning `{existed: boolean; alreadyTerminal: boolean}`
  instead of resolving void on both 204 and 404. Real signal-loss
  but tagged "[非阻塞]" by the reviewer; changing requires a
  daemon route shape change (200 + body instead of 204) which is
  better as a focused follow-up PR. Acknowledged in-thread;
  deferred to a fold-in PR after #4255 lands.

- `npm run typecheck` — clean across `packages/{cli,sdk-typescript,core}`
- `npx vitest run packages/cli/src/serve/
  packages/sdk-typescript/test/unit/daemonEvents.test.ts` — 398/398
- `npx eslint --max-warnings 0` over the PR 21 surface — clean

Refs: #4175 #4255

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

* fixup(serve): address PR #4255 wenshao round-4 review feedback

4 threads from the fourth review pass on #4255. 3 adopted + 1
deferred (out-of-scope rename of PR 15's `mutate` helper).

## Adopted

### #1 — `persistInFlight` flag suppresses cancel × persist event-stream UX trap

When `provider.poll()` returns success and we await `persist()`, a
concurrent `cancel()` would synchronously transition the entry to
`cancelled` and emit `auth_device_flow_cancelled` — then `persist()`
resolves and (per fold-in 3 C4) force-overrides to `authorized` +
emits `auth_device_flow_authorized`. The reducer state correctly
last-write-wins on `authorized`, but DIRECT event-stream consumers
(close-dialog handlers, telemetry, UI cleanup) race onto an unmounted
UI when the second event lands.

Now: while persist is in-flight, `cancel()` and the sweeper SKIP the
state transition + event emit. They register intent (set
`cancelRequestedDuringPersist=true` for cancel; sweeper just no-ops)
and let the persist resolution decide:

- persist succeeds → `authorized` (IdP wins per fold-in 3 C4)
- persist fails AND cancel was requested → `cancelled`
- persist fails AND `now >= expiresAt` → `expired` / `expired_token`
- persist fails otherwise → `error` / `persist_failed`

Result: at most one terminal event per flow. Imperative SSE
consumers no longer see oscillating terminal states. Audit captures
the race (`hint: 'lost_success_kept ...'`) for incident-response
correlation.

### #2 — `revealSecret` → `unsafeRevealSecret` rename

The earlier JSDoc claimed "the `unsafeReveal_` naming is intentional:
greppable in code review, easy to allowlist in lint rules, hard to
invoke by accident" — but the actual function was named
`revealSecret`. The promised safety properties didn't exist; a code
reviewer wouldn't single out `revealSecret` as suspicious, and a
`no-restricted-syntax` ESLint rule wouldn't flag it.

Renamed to `unsafeRevealSecret` so the JSDoc-promised "greppable" /
"lintable" property is now actually true. Two call sites in the
Qwen provider + 4 test references updated. Internal symbol; not
exposed through the SDK package.

### #4 — `QwenOAuthPollError` typed class replaces substring regex

The earlier RFC 8628 error mapper used an anchored regex against the
thrown error message text — an implicit cross-file string contract
between `qwenOAuth2.ts` (throws) and `qwenDeviceFlowProvider.ts`
(matches). If `qwenOAuth2.ts` ever changed its message format, ALL
RFC 8628 errors (`expired_token` / `access_denied` / `invalid_grant`)
would silently fall through to `upstream_error` — wrong errorKind
flowing through telemetry with no test or type-system check to catch
the drift.

Now `QwenOAuth2Client.pollDeviceToken` throws a structured
`QwenOAuthPollError extends Error` with `oauthError` / `description`
/ `status` fields. The provider branches on `instanceof
QwenOAuthPollError` and reads `.oauthError` directly via a
dedicated `mapRfc8628OAuthCode(code)` switch. The drift hazard is
gone: a future code change that touches the typed class will
fail tsc until both sides are updated. Message format preserved
for any pre-existing log-parsing / substring matchers.

## Not adopted

### #3 — `mutate({strict:true})` semantic awkwardness on GET

Reviewer correctly noted that `mutate` is named for state-changing
routes, but `GET /workspace/auth/device-flow/:id` uses it for an
information-disclosure defense (only reachable code path is reading
state). Suggested rename: `mutate` → `strictHttpGate`.

Deferred: the rename touches PR 15's helper which has many call
sites in `server.ts` and is shared infrastructure for Wave 4 PRs
17/19/20. PR 21 is the first / only consumer of the strict-on-GET
form so far; widening the rename to a Wave 4 follow-up keeps the
fold-in scope tight. Replied in-thread.

## Validation

- `npm run typecheck` — clean across `packages/{cli,sdk-typescript,core}`
- `npx vitest run packages/cli/src/serve/
  packages/sdk-typescript/test/unit/daemonEvents.test.ts` — 544/544
- `npx eslint --max-warnings 0` over the PR 21 surface — clean

Refs: #4175 #4255

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

* fixup(serve): address PR #4255 wenshao round-5 review feedback

Five small adopt items from the round-5 review pass; one stale thread
already addressed in b5b77ee90 (fold-in 5).

#2 — `as const` + derived type for DEVICE_FLOW_SUPPORTED_PROVIDERS so
adding/removing a provider id requires touching exactly ONE site.
Mirrors `SERVE_ERROR_KINDS` / `ServeErrorKind` in `status.ts`.

#3 — Clarify `DEVICE_FLOW_EXPIRY_GRACE_MS` JSDoc to distinguish the
daemon's 30s SWEEP cadence (what the grace tracks) from the 5-min
TERMINAL_GRACE_MS reconnect window (which awaitCompletion does NOT
need to wait through).

#4 — Add `@remarks` block on `DeviceFlowProvider.poll()` warning
future provider authors that thrown `err.message` flows verbatim
into the SSE-broadcast `auth_device_flow_failed` hint, and must be
sanitized. Two equally-correct paths documented (typed `error`
result vs sanitized thrown message).

#5 — Truncate raw IdP detail in `qwenDeviceFlowProvider.ts` stderr
audit lines to 2 KiB. WAFs / reverse proxies can return MB-sized
HTML error pages, and container log aggregators (Loki, Fluent Bit,
Stackdriver) typically truncate or drop lines past 4-32 KiB —
losing the useful prefix downstream. 2 KiB retains structured JSON
envelopes while staying well below every aggregator's per-line cap.

#6 — Track latest `originatorClientId` on per-provider singleton
take-over via new `entry.lastOriginatorClientId` field +
`recordTakeover()` helper. When a second SDK client posts
`POST /workspace/auth/device-flow` for an already-pending provider
(or one being created in `inFlightStarts`) with a different
`initiatorClientId`, an audit breadcrumb records the take-over so
incident response can correlate "client A started, client B took
over at 12:34". Event-routing intentionally still uses the original
`initiatorClientId` (events are workspace-broadcast and changing
the originator field mid-flow would break SDK reducers that key on
it). Two new tests cover the differing-id audit + same-id no-op.

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

* fixup(serve): address PR #4255 wenshao round-6 review feedback

Six "Critical" findings from a gpt-5.5 /review pass — all real
liveness/correctness defects in the daemon's auth device-flow path
and the SDK's awaitCompletion polling loop.

#1 — Make `provider.start()` timeout authoritative via `Promise.race`
in `DeviceFlowRegistry.doStart`. The earlier shape only ABORTED the
signal on timeout; a provider that ignores `signal` (non-abortable
I/O, future implementer who forgets to thread it to `fetch`) would
leave the `await` hanging until daemon restart, pinning the
`inFlightStarts` slot for that providerId. Race against a rejecting
timer makes the timeout authoritative regardless of provider
cooperation; abort still fires for cooperative cleanup.

#2 — Same shape for `result.persist()` in the success branch of
`runPollTick`. A future provider whose persist performs
non-abortable steps (mkdir/chmod/mv outside the abortable
fs.writeFile path) would otherwise hang the poll tick until process
restart. Race against rejecting timer; rejection maps to
`persist_failed`.

#3 — Clamp `expiresIn` and `interval` upper bounds. Previous
`Number.isFinite + > 0` guards stopped NaN/Infinity but a finite
extreme like `1e12` was still accepted — pinning the per-provider
singleton for ~30,000 years (`expires_in`) or scheduling a
TIMEOUT_MAX-clamped poll that never fires within `expiresAt`
(`interval`). Two new constants (`DEVICE_FLOW_MAX_EXPIRES_IN_SEC =
3600`, `DEVICE_FLOW_MAX_INTERVAL_MS = 60_000`) cap the worst case.

#4 — Extract `getDeviceFlowOrSynthetic404(...)` helper in
`DaemonAuthFlow.ts` and route BOTH the loop body and the
timeout-ceiling final read through it. Previously the ceiling read
went directly through `client.getDeviceFlow` and a 404 at the
boundary (entry evicted just as the timeout fired) would reject with
`DaemonHttpError(404)` instead of returning the structured `{ status:
'error', errorKind: 'not_found_or_evicted' }` that the rest of
`awaitCompletion` promises.

#5 — Validate `AwaitCompletionOptions.timeoutMs` and `pollOverrideMs`
with `Number.isFinite + > 0`. NaN slipped past the previous `??
default` form (NaN is truthy-ish in that position) and produced a
`ceiling` of `NaN` (loop runs forever — `now >= NaN` always false)
or a `setTimeout(NaN)` (Node clamps to 1ms — tight polling loop).
Sanitize to `undefined` so the documented defaults take effect.

#6 — Thread `signal` into `DaemonClient.getDeviceFlow` and forward
to `fetchWithTimeout` (which already composes caller + timeout
signals). awaitCompletion now passes `opts.signal` from both GET
sites. Without this, an `awaitCompletion` caller that aborts mid-
poll could not cancel an in-flight stalled GET; it would have to
wait for the daemon-side `fetchTimeoutMs` (30s default) to fire.

Four new tests in `deviceFlow.test.ts` pin the new behaviors:
hanging-start timeout (#1), hanging-persist → persist_failed (#2),
extreme-expiresIn clamp (#3), extreme-interval clamp (#3).
FakeProvider gained a `startHangs` flag for the non-cooperative
provider scenario.

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

* fixup(serve): address PR #4255 wenshao round-7 review feedback

Two findings from a DeepSeek /review pass; both small but legitimate
defense-in-depth gaps.

#1 — `runPollTick`'s catch block forwarded `err.message` verbatim
into the SSE-broadcast `hint`. The provider's `@remarks` contract
(fold-in 6 #4) requires throwers to sanitize, but if violated the
unbounded raw payload would reach every SSE subscriber. Added
`DEVICE_FLOW_POLL_HINT_MAX_LEN = 256` + `truncatePollHint()`,
applied to the catch's `result.hint`. Full raw `err.message` is
still routed to the audit trail (`audit?.record({hint: 'provider.poll()
threw (raw): ...'})`) so operator visibility for incident response
is preserved. Belt-and-suspenders: the contract is now structurally
enforced rather than relying on every future provider author to
read the JSDoc.

#2 — `updateMatchingFlow` (and the `started`/`authorized` handlers
in `reduceDaemonAuthEvent`) unconditionally overwrote state without
comparing `rawEvent.id` against the existing flow's
`lastSeenEventId`. The field's JSDoc documented it as a monotonic
counter to prevent stale frames from overwriting newer state, but
the code didn't enforce that contract. SSE reconnect with
`Last-Event-ID < terminal-frame-id` would replay older frames; if
any of them were for the same `deviceFlowId` (e.g. a delayed
`failed` arriving after `authorized`) the stale frame would
overwrite the terminal. Daemon-side `transitionTerminal` makes the
exact reachable scenario thin, but the documented contract should
match the code.

Threaded `rawEventId` into `updateMatchingFlow` and added the gate
there + in the `started` and `authorized` handlers (the two cases
that don't go through `updateMatchingFlow`). Synthetic frames
without an envelope `id` (`rawEventId === undefined`) bypass the
gate — they originate inside SDK reducer machinery and aren't
subject to replay ordering.

Three new tests pin the contracts:
- `runPollTick catch truncates the SSE hint and preserves raw on
  the audit (fold-in 8 #1)` — `pollThrowsWith` flag on FakeProvider
  models a non-conforming provider; SSE hint < 400 chars + contains
  'truncated'; audit hint contains the full 4_000-char raw.
- `reduceDaemonAuthEvent rejects out-of-order frames (fold-in 8 #2
  monotonicity)` — stale `failed`(id=7) does NOT overwrite
  `authorized`(id=10); stale `started`(id=4) for a different flow
  also rejected.
- `reduceDaemonAuthEvent passes synthetic frames (no envelope id)
  through the gate` — SDK-internal frames without `id` are honored.

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

* fixup(serve): address PR #4255 wenshao round-8 review feedback

Twelve correctness + structural fixes from a wenshao + DeepSeek + gpt-5.5
review pass. Tests deferred to fold-in 10 (separate, larger commit).

CRITICAL CORRECTNESS

#7 — `provider.persist()` Promise.race could publish `persist_failed`
to SSE while a non-cooperative provider was still committing
credentials to disk. Added an independent tracker on the original
persist promise: if the race timed out (`persistTimedOut === true`)
AND the underlying persist later resolved successfully, audit a
`lost_success_after_timeout` breadcrumb so operators see the
inconsistency. Tightened the persist `@remarks` contract to require
signal honoring end-to-end. Qwen provider already complies (fold-in
3 #10); this is forward-defense for future providers.

#11 — auth surface (`DaemonAuthFlow`, `reduceDaemonAuthEvent`,
`createDaemonAuthState`, `DEVICE_FLOW_EXPIRY_GRACE_MS`, all event /
data / state types) was re-exported from `src/daemon/index.ts` but
NEVER from the published SDK entry `src/index.ts`. SDK consumers got
`undefined` for everything except `client.auth.start()` (which
traveled through the already-exported `DaemonClient`). Added the
missing exports and pinned via `daemon-public-surface.test.ts`.

#12 — `core/src/qwen/qwenOAuth2.ts:373`'s
`debugLogger.debug('Device authorization result:', result)` writes
the raw `device_code` (RFC 8628 bearer-equivalent credential) to
stderr / journald, bypassing the `BrandedSecret` redaction layer.
Pre-existing on main but PR 21 expanded the exposure surface.
Sanitized to log only `{ ok, expires_in }` on success / `{ ok,
error }` on error.

#13 — `runPollTick` success-branch persist-failure × past-`expiresAt`
classified as `expired_token` instead of `persist_failed`, routing
operators toward "tell user to retry" (RFC 8628 expiry) when the
actual root cause was disk I/O. Reclassified to `persist_failed`
with a `persist_also_failed_past_expiry` audit hint to preserve the
timing detail for incident response.

SMALL CORRECTNESS

#1 — `runPollTick` catch hint replaced with a STATIC bounded message
("provider.poll() failed; see daemon audit log for details"). The
fold-in 8 truncated-prefix approach could still leak the first 256
chars of provider-templated raw text including secret material. Full
raw still routed to audit channel for operator visibility.

#5 — `cancellerClientId` field added to `DeviceFlowEntry`; deferred-
cancel branch in `cancel()` now stamps it on the entry, and the
persist-resolution `cancelled` event publish uses
`entry.cancellerClientId ?? entry.initiatorClientId`. SSE consumers
that suppress self-emitted events can now attribute the cancel
correctly.

#6 — `AwaitCompletionOptions.timeoutMs === 0` (the documented
"settle immediately, return current daemon view" contract) was
treated as falsy by the `?` ternary, falling back to the default.
`sanitizePositiveMs` now takes an `allowZero` opt-in; the ceiling
computation uses `!== undefined` instead of truthy check.

#8 — `EventBus.publish()` returns `undefined` for closed buses (it
does NOT throw). `broadcastWorkspaceEvent` previously counted that
path as success, hiding the all-buses-dropped operator alarm.
Folded the closed-bus-as-failure check into the canonical
`publishWorkspaceEvent` (see #X below).

#9 — start-timeout Promise.race rejected with a plain `Error`,
falling through `sendBridgeError` to a generic 500. Switched to
`UpstreamDeviceFlowError` so a hung IdP correctly surfaces as 502
(matching the envelope every other IdP start failure uses).

STRUCTURAL

#3 — Three identical `transitionTerminal + publish + audit`
expired_token blocks in `runPollTick`/`sweep`/(removed by #13)
deduplicated into a private `expireEntry()` helper. Future event-
shape changes are now a one-edit operation.

#X — PR 16 (#4249) merged on 2026-05-18 06:27Z. Per the inline
comment at httpAcpBridge.ts:501, PR 21's `broadcastWorkspaceEvent`
was kept distinct only to avoid the merge conflict; once PR 16
landed, it became a fold-in candidate. Folded the closed-bus +
all-failed-stderr-escalation operator-visibility features (PR 21's
S5 + fold-in 9 #8) INTO `publishWorkspaceEvent`; dropped
`broadcastWorkspaceEvent` from the bridge interface + impl + test
mocks. PR 21's deviceFlowEventSink now calls
`bridge.publishWorkspaceEvent` — single canonical workspace fan-out.

DOC

#16 — Added a "Cross-client take-over" paragraph to
`docs/users/qwen-serve.md` explaining that two clients on the same
daemon for the same provider get the per-provider singleton with
`attached: true`/`false` distinguishing them; no separate event
fires (both eventually observe the same `auth_device_flow_authorized`).

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

* fixup(serve): address PR #4255 wenshao round-9 review feedback

Two small non-blocking items from the round-9 pass; defensive shape +
docs only. The 4 deferred test-coverage threads (#1-4 of round-8) are
still tracked for fold-in 10.

#6 — `lastSeenEventId` typed `number` with `?? 0` defaults in the
`auth_device_flow_started` reducer case. The daemon-side `EventBus`
assigns ids ≥ 1 so the `0` sentinel has no real-traffic meaning, but
the monotonic gate (`rawEventId <= flow.lastSeenEventId`) would
reject any future SDK-internal synthetic frame using `id: 0`.
Changed the field type to `number | undefined` and dropped the
`?? 0` from the started case. The `updateMatchingFlow` /
`auth_device_flow_authorized` guards already short-circuit on
`existing.lastSeenEventId !== undefined`, so undefined is safe
end-to-end. Existing 34 reducer tests still pass unchanged.

#7 — Added `@remarks` block to `DeviceFlowErrorKind.persist_failed`'s
JSDoc explaining the lost-success retry UX. When fold-in 9 #7's
`lost_success_after_timeout` audit fires (non-conforming provider
violates signal contract; disk write succeeds after registry
published `persist_failed`), a naive SDK retry hits the IdP a
second time with a fresh `device_code` and prompts the user
twice — but the first credential set is already valid. JSDoc now
documents the mitigation: SDK consumers writing retry logic on
`persist_failed` should call `client.auth.getStatus()` BEFORE
re-prompting; operators can grep stderr/audit for
`lost_success_after_timeout` to detect occurrences.

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

* test(serve): fold-in 10 — auth device-flow test bundle (#4255)

Lands the four deferred test-coverage items the round-8 review
flagged (and round-9 re-surfaced) as a hard merge prerequisite.
Net +41 tests across registry / SDK helper / client HTTP /
HTTP route layers.

#1 — `deviceFlow.test.ts` `persist failure paths` describe (3
tests, +3). The success arm's three terminal mappings — pure
`persist_failed`, `cancelled` (cancel during persist), and
`persist_failed` past `expiresAt` (the fold-in 9 #13
reclassification with `persist_also_failed_past_expiry` audit
hint) — were 0-covered. Now pinned. Test #2 also asserts the
fold-in 9 #5 cancellerClientId routing on the deferred
`cancelled` event.

#2 — new `DaemonAuthFlow.test.ts` (+14 tests). Mock DaemonClient
with sequenced `getDeviceFlow` replies. Covers happy-path
polling → `authorized`; `slow_down`-driven `intervalMs` bump
firing `onThrottled`; `signal.abort()` rejection; `signal`
propagation through `client.getDeviceFlow` (fold-in 7 #6);
`timeoutMs` ceiling final-read; `timeoutMs:0` immediate-return
(round-9 #6); NaN/Infinity → `sanitizePositiveMs` fallback to
default ceiling (fold-in 7 #5); 404 → synthetic
`error`/`not_found_or_evicted` (fold-in 3 #4) at BOTH the loop
body AND the timeoutMs ceiling read (fold-in 7 #4); non-404
DaemonHttpError rethrown; `cancel()` and top-level
`status()`/`cancel()` wrappers forward correctly.

#3 — `DaemonClient.test.ts` `device-flow methods` describe
(+11 tests). POSTs `/workspace/auth/device-flow` happy path +
clientId header + body shape; 200/201 acceptance; non-2xx →
`DaemonHttpError`. GETs URL-encode the deviceFlowId; forward
`opts.signal` to `fetchWithTimeout`'s composed signal (fold-in
7 #6 — verified by aborting caller signal and observing the
fetch's signal flip to `aborted`); 404 throws. DELETEs
swallow 204 + 404 (idempotent, mirrors `closeSession`); non-
204/404 throws. `getAuthStatus` plain GET. `client.auth`
lazy-instantiated singleton.

#4 — `server.test.ts` 5 supplementary contract tests (+5).
The existing 8 `it()`s cover happy paths + take-over + 401
POST + DELETE pending/terminal/unknown + 502 upstream + sweeper.
This commit plugs gaps: 400 `invalid_request` for missing /
non-string providerId (fold-in W2 split this from
`unsupported_provider`); 409 `too_many_active_flows` (via
injected fake registry); 401 `token_required` on DELETE
without bearer; the asymmetric GET posture
(`/workspace/auth/device-flow/:id` IS strict-gated to prevent
peer-process userCode shoulder-surf; `/workspace/auth/status`
stays read-only because its `pendingDeviceFlows` entries
intentionally redact `userCode`).

Validation: cli serve 631/631 (+8 from #1, #4); sdk 384/384
(+25 from #2, #3, +/- some pre-existing churn). Typecheck +
lint clean.

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

* fix(qwen): atomic temp+chmod+rename in cacheQwenCredentials (PR #4255 round-11 #2)

gpt-5.5 /review flagged a real correctness/security gap: the
post-write `chmod` ordering left a window where freshly-written
credentials could land in a broadly-readable existing
`oauth_creds.json` before the chmod tightened it. On POSIX, a
chmod failure additionally degraded to a debug warning while the
broadly-readable tokens stayed on disk.

New shape mirrors the standard atomic-write idiom:

  1. Write `${filePath}.tmp.${pid}.${randomUUID()}` with `mode: 0o600`.
     The temp path doesn't exist beforehand, so the `mode` flag
     actually applies on creation (it doesn't on existing files,
     which was the root of the original race).
  2. Defensive `chmod` on the temp file. POSIX failure is now a
     HARD ERROR (refuses to publish broad-perm credentials to the
     canonical filename). Windows logs a debug breadcrumb and
     proceeds, since chmod is a no-op on most NTFS volumes (perms
     go through ACLs).
  3. Atomic `fs.rename` over `filePath`. The canonical path is
     ALWAYS at `0o600` from the moment it contains the new tokens;
     readers see either the old creds or the new creds, never a
     partially-written or broadly-readable state.
  4. Best-effort `fs.unlink` of the temp file on any failure path
     so failed writes don't leave `.tmp.<pid>.<uuid>` litter on
     disk.

Test mock in `qwenOAuth2.test.ts` extended with `chmod` + `rename`
no-op stubs so the existing 158 core/qwen tests still pass; no test
behavior change beyond the mock surface.

Validation: typecheck clean (cli + core + sdk-typescript); core
qwen 158/158; cli serve 643/643; sdk 384/384.

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

* fixup(serve): address PR #4255 wenshao + gpt-5.5 round-12 review feedback

Eight findings from a wenshao + gpt-5.5 /review pass: 1 critical
correctness, 2 real defensive defects, 4 edge cases / minor
hardening, 1 test gap. All adopted.

CRITICAL CORRECTNESS

#1 CzSpN — `dispose()` race: after `await provider.poll(...)` the
post-await guard checked only `entry.status !== 'pending'`, NOT
`this.disposed`. `dispose()` clears the registry maps and aborts
the entry's signal but doesn't mutate `entry.status`, so a
provider whose poll already resolved (or doesn't honor abort) could
enter the success branch and call `result.persist({...})` —
committing credentials on a shutting-down daemon. Added the
`if (this.disposed) return;` guard symmetric with the top-of-method
check.

REAL DEFENSIVE DEFECTS

#2 Cy_ZG — sync-throw escape: the `result.persist({signal})` call
happens BEFORE the `new Promise` constructor that captures it
(`persistTracker` is closed-over inside the constructor). A
non-conforming provider whose persist throws synchronously (e.g.
top-of-function validation) would escape past the outer
`try/catch (await new Promise(...))` and become an
`unhandledRejection` since `runPollTick` is fire-and-forget via
`void`. Wrapped the persist invocation in a try/catch that routes
the sync-throw into the same `persistError` branch.

#3 CzSpe — runtime provider map: provider validation hardcoded
`DEVICE_FLOW_SUPPORTED_PROVIDERS` even though `deps.deviceFlowProviders`
is the documented extension hook for tests/future providers.
Switched both POST validation and `/workspace/auth/status`
`supportedDeviceFlowProviders` to derive from
`deviceFlowProviderMap.keys()` — single source of truth matches
the registry's `resolveProvider`.

EDGE CASES / MINOR HARDENING

#4 Cy_Y9 — `slow_down` re-clamp: `intervalMs += SLOW_DOWN_BUMP_MS`
can push past `DEVICE_FLOW_MAX_INTERVAL_MS` (the bound that keeps
`setTimeout` from clamping to TIMEOUT_MAX). Wrapped in
`Math.min(MAX_INTERVAL_MS, ...)` symmetric with the doStart clamp.

#5 Cy_ZF — `expiresInSec` lower bound: `0.5` was finite-positive
and produced `expiresAt = now() + 500 ms` — first poll (clamped at
≥1 s) fires AFTER expiresAt → flow expires before any user could
authorize. Added `DEVICE_FLOW_MIN_EXPIRES_IN_SEC = 30` (RFC 8628
§3.2 calls 5–30 minutes "reasonable"; sub-30s is non-compliant).

#6 CzHOK — take-over response privacy: `initiatorClientId` was
echoed to ANY take-over POST caller, including those with no
`X-Qwen-Client-Id` header. Bearer-gated already, but the
asymmetry "anonymous caller learns who started it" violated the
no-header-as-privacy-signal contract. Now only echoed when the
caller's id matches the entry's initiator.

#7 CzSpd — production audit visibility: production audit sink
dropped `line.hint`, but the registry uses hints for operator-only
breadcrumbs (`provider.poll() threw (raw)...`,
`lost_success_after_timeout`, `persist_also_failed_past_expiry`,
take-over correlation, `deferred (persist in flight; ...)`). The
documented troubleshooting trail was invisible in production
stderr. Now included with a 1 KiB bound + JSON-quoted so multi-
word hints stay parseable.

TEST GAP

#8 Cy_ZH — `lost_success_after_timeout` audit: the
fold-in 9 #7 split-brain detector for non-cooperative providers
had no test pinning it. Added a controllable `latePersist` Promise
+ test that drives poll → success → enters persist race → fires
PERSIST_TIMEOUT (registry publishes persist_failed) → resolves
persist late → asserts the lost_success audit fires.

Validation: typecheck + lint clean; cli serve 644/644 (+1 from
the new test); sdk-typescript 384/384.

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

* fixup(serve): close concurrent multi-provider cap bypass (PR #4255 round-13 #1)

gpt-5.5 /review caught a real workspace-wide cap bypass:
`countActive()` only counted entries already installed in
`byProvider`, but the cap check at the top of `start()` runs
before any provider's `inFlightStarts` slot completes
`provider.start()`. A burst of fresh starts for
`DEVICE_FLOW_MAX_CONCURRENT + 1` distinct providers all run
synchronously to the cap check (each `start()` is async but
runs to its first await — the await happens AFTER the cap
check), all observe `count === 0` (no `byProvider` entries
installed yet), and all pass — eventually installing more
than the documented four pending flows.

Fix: include `inFlightStarts.size` in `countActive()`. The
two maps are disjoint by construction (the existing-pending
fast-path catches any provider with both), so simple
addition cannot double-count. The second concurrent caller
sees count=1, the third count=2, …, and the (MAX+1)th caller
is rejected with `TooManyActiveDeviceFlowsError`.

Test: `caps at DEVICE_FLOW_MAX_CONCURRENT under CONCURRENT
distinct-provider starts`. Fires `MAX+1` concurrent starts
via `Promise.allSettled`, asserts exactly `MAX` fulfilled +
exactly 1 rejected with the typed error. Pre-fix this test
fails (all `MAX+1` succeed); post-fix it passes.

Validation: typecheck clean across all 4 workspaces;
deviceFlow.test.ts 35/35 (was 34); cli serve 645/645.

🤖 Generated with [Qwen Code](https://github.com/QwenLM/qwen-code)

Co-authored-by: Jack Wotherspoon <jackwoth@google.com>