Squashed feature work from daemon_mode_b_main branch, rebased onto
latest main to establish proper merge-base and clean PR diff.

Original commits:
- perf(core): F2 cleanup PR A — R9/W11/W12/R10 (post-merge follow-ups) (#4411)
- refactor(acp-bridge): F1 test split — lift bridge.test.ts (6861 LOC) to acp-bridge (#4445)
- fix(core): F2 cleanup PR B — self-heal observability (W133-a + W134) (#4460)
- feat(sdk/daemon-ui): unified completeness follow-up to #4328 (#4353)
- docs(serve): v0.16-alpha known limits + SDK QWEN_SERVER_TOKEN env fallback (PR 27) (#4473)
- docs(deploy): local launch templates for v0.16-alpha (PR 30a) (#4483)
- feat(daemon+sdk): cross-client real-time sync completeness (#4484)
- feat(serve): add POST /session/:id/recap (#4504)
- feat(daemon): add voterClientId to permission_resolved (A4) (#4539)
- feat(serve): --allow-origin <pattern> CORS allowlist (T2.4 #4514) (#4527)
- feat(daemon): in-session model switch reaches the bus (A1) (#4546)
- feat(serve): prompt absolute deadline + SSE writer idle timeout (#4514 T2.9) (#4530)
- Feat/daemon react cli (#4380)

…lback (PR 27) (#4473)

* docs(serve): v0.16-alpha known limits + SDK QWEN_SERVER_TOKEN env fallback (PR 27)

First PR in the F5 release chain (PR 27 → 28 → 30a → 31) per the
2026-05-24 v0.16-alpha scope freeze in #4175 (text-only chat / coding
+ local-only deployment).

## SDK ergonomic micro-change (~50 LOC + 4 tests)

`DaemonClient` constructor falls back to `QWEN_SERVER_TOKEN` env
var when `opts.token` is absent — closes the asymmetry where the
daemon side already honors this var (--token CLI flag fallback,
already in main since PR 15) but the SDK forced clients to thread
it through every construction.

Properties:
- Browser-safe via `globalThis.process` indirection (the SDK is
  imported by @qwen-code/webui; literal process.env access would
  explode at module load on browser bundles)
- Whitespace stripped (matches daemon-side trim — handy for
  `export QWEN_SERVER_TOKEN=\"\$(cat token.txt)\"` where cat adds a
  trailing newline)
- Empty / whitespace-only treated as unset (a stale
  `export QWEN_SERVER_TOKEN=\"\"` won't accidentally send
  Authorization: Bearer with no token)
- Resolved at construction, not lazily per-request (later
  process.env mutations don't affect already-built clients)
- Explicit opts.token wins over env

Tests: 4 new in DaemonClient.test.ts `bearer auth` describe
covering env fallback / explicit-wins / empty-treated-unset /
whitespace-stripped. Plus a defensive snapshot/restore on the
existing 'omits Authorization when no token' test so an
inherited test-runner export of QWEN_SERVER_TOKEN doesn't turn
that assertion into a false positive.

This SDK fallback is the entire ergonomic replacement for PR 29's
SDK env/file fallback. PR 29's other features (auto-gen daemon
token, instance-path keying, stale cleanup) remain deferred to
v0.16.x — all are DX improvements over the boot-time security gate
already shipped in PR 15.

## v0.16-alpha docs (~120 LOC markdown)

- docs/users/qwen-serve.md: new "v0.16-alpha known limits" section
  enumerating product surface (text-only ✅, multimodal ❌),
  deployment surface (local launchers ✅, containerized ❌, multi-
  daemon ❌, BYO-token ✅), and hardening posture (boot security
  gate ✅, mutation gate ✅, MCP guardrails ✅, prompt absolute
  deadline ⏸️, rate limiting ⏸️, --max-body-size ⏸️). Adds an
  alpha banner at the top of the file.

- docs/developers/examples/daemon-client-quickstart.md:
  documents the SDK env fallback in both the Hello-daemon
  intro and the Authentication section, with the "export +
  no-token-arg" recommended path called out for local dev.

Verification: 125/125 DaemonClient.test.ts pass (121 existing +
4 new); 4/4 daemon-public-surface.test.ts pass (constructor
signature unchanged); tsc clean on packages/sdk-typescript;
eslint --max-warnings 0 clean on touched .ts files.

Part of #4175.

* fix(sdk): #4473 round 1 fold-in — 2 copilot doc threads adopted

T1 [copilot DaemonClient.ts:144 — stale line refs in readTokenFromEnv
  JSDoc]: removed `runQwenServe.ts:175` (token resolution actually
  lives at line 302-318 today, would drift again on next refactor)
  and `docs/users/qwen-serve.md:173`. Replaced with stable
  symbol/section references ("runQwenServe token-resolution path";
  "qwen-serve user guide CLI flags section").

T2 [copilot daemon-client-quickstart.md:33 — `~/.qwen/server-token`
  implies built-in path that doesn't exist]: PR 27 explicitly defers
  token auto-generation + file-store fallback (PR 29 deferred features).
  The example incorrectly suggested a standard file location.
  Replaced with two explicit user-managed alternatives:
  - `openssl rand -hex 32` one-shot
  - `cat ./my-token-file` user-managed file

Both threads were accurate suggestions caught at the right time
(zero behavior change; pure docstring/example accuracy).

Verification: 125/125 DaemonClient tests pass; tsc + eslint clean
on touched files.