feat(channel): add daemon bridge spike

docs/developers/daemon-client-adapters/channel-web.md

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+# Channel And Web Backend Daemon Adapter Draft
+
+## Goal
+
+Let channel adapters and web chat backends consume `qwen serve` through
+`DaemonSessionClient` while keeping existing channel ACP subprocess behavior as
+the default.
+
+This draft covers server-side clients only:
+
+- Channel bot backend -> `qwen serve`
+- Web browser -> web backend / BFF -> `qwen serve`
+
+It explicitly does not allow browser JavaScript to call the daemon directly.
+The daemon currently rejects browser `Origin` requests by design.
+
+## Proposed Entry Points
+
+Channel backend:
+
+```bash
+QWEN_CHANNEL_DAEMON_URL=http://127.0.0.1:4170 qwen channel start telegram
+```
+
+Web backend:
+
+```bash
+QWEN_WEB_DAEMON_URL=http://127.0.0.1:4170 qwen web-chat-backend
+```
+
+Shared optional variables:
+
+```bash
+QWEN_DAEMON_TOKEN=...
+QWEN_DAEMON_WORKSPACE=/repo
+```
+
+## Minimal Channel Flow
+
+This PR adds `DaemonChannelBridge`, a locally verifiable server-side bridge for
+channel and web-backend adapters. It keeps the existing ACP bridge as the
+default and owns daemon session state inside the backend process.
+
+1. Resolve channel sender/thread to a channel session key.
+2. Use `DaemonClient` + `DaemonSessionClient.createOrAttach()`.
+3. Submit inbound user text with `session.prompt()`.
+4. Subscribe to `session.events()` and collect assistant text chunks.
+5. Send final text back through the platform adapter.
+6. Cast permission votes through `session.respondToPermission()`.
+7. Cancel active work through `session.cancel()`.
+
+## Minimal Web Backend Flow
+
+1. Browser opens a websocket or HTTP stream to the web backend.
+2. Backend owns `DaemonSessionClient`.
+3. Backend translates browser messages to daemon prompts.
+4. Backend translates daemon SSE events to browser-safe app events.
+5. Backend stores the daemon `sessionId` and last seen event id server-side.
+
+Browser clients must not receive daemon bearer tokens.
+
+## Session Isolation Constraint
+
+Current daemon Stage 1 behavior is effectively `sessionScope: single` at the
+daemon setting level. Until per-request `sessionScope` lands, multi-user channel
+or web deployments must choose one of these safe shapes:
+
+- one daemon per channel thread / web room
+- one daemon per user workspace
+- single-user demo only
+
+Do not silently multiplex unrelated channel threads into one daemon session.
+
+## Event Mapping Contract
+
+| Daemon event                             | Channel/web backend handling           |
+| ---------------------------------------- | -------------------------------------- |
+| `session_update` / `agent_message_chunk` | Append assistant text                  |
+| `session_update` / `agent_thought_chunk` | Optional hidden/debug stream           |
+| `session_update` / `tool_call`           | Emit tool status card/message          |
+| `permission_request`                     | Platform-specific approval interaction |
+| `permission_resolved`                    | Close/update approval interaction      |
+| `model_switched`                         | Update backend session metadata        |
+| `session_died`                           | Notify user and stop stream            |
+
+Unknown daemon events must be ignored or forwarded as debug metadata, not fatal.
+
+The bridge is not wired into `qwen channel start` yet. Existing Telegram,
+Weixin, Dingtalk, plugin channel, and browser behavior remains unchanged.
+
+## Explicit Non-Goals
+
+- No browser direct-to-daemon fetch or EventSource.
+- No CORS relaxation in this adapter PR.
+- No default migration of Telegram, Weixin, Dingtalk, or plugin channels.
+- No file CRUD, memory CRUD, MCP restart, or provider mutation.
+- No sessionScope emulation in the client when daemon-side support is absent.
+
+## Merge Safety
+
+- Default off.
+- Existing ACP channel bridge remains the default.
+- Web backend is an explicit BFF layer, not a daemon security change.
+- No channel adapter should import daemon tokens into frontend/browser code.
+
+## Validation Plan
+
+- Unit-test channel session-key to daemon-session binding.
+- Unit-test daemon event to channel/web message mapping.
+- Unit-test prompt, cancel, model switch, and permission response forwarding.
+- Smoke-test one single-user channel backend against local `qwen serve`.
+- Smoke-test browser -> BFF -> daemon without exposing daemon token.
+
+## Blockers Before Default Migration
+
+- Per-request `sessionScope`.
+- Session metadata + close/delete lifecycle.
+- Daemon-stamped client identity.
+- Session-scoped permission route.
+- Read-only diagnostics for MCP, skills, providers, and environment.