feat(im): Add user-owned IM channel connections (#3487)

* Add user-owned IM channel connections

* Fix dev startup and channel connect popup

* Use async channel connect flow

* Harden dev service daemon startup

* Support local IM channel connections

* Align IM connections with local channels

* Fix safe user id digest algorithm

* Address Copilot IM channel feedback

* Address IM channel review comments

* Support all integrated IM channel connections

* Format additional channel connection tests

* Keep unavailable channel connect buttons clickable

* Fix IM channel provider icons

* Add runtime setup for enabled IM channels

* Guard global shortcut key handling

* Keep configured IM channels editable

* Avoid password autofill for channel secrets

* Make channel threads visible to connection owners

* Persist IM runtime config locally

* Allow disconnecting runtime IM channels

* Route no-auth channel sessions to local user

* Use default user for auth-disabled local mode

* Show IM channel source on threads

* Prefill IM channel runtime config

* Reflect IM channel runtime health

* Ignore Feishu message read events

* Ignore Feishu non-content message events

* Let setup wizard enable IM channels

* Fix frontend formatting after merge

* Stabilize backend tests without local config

* Isolate channel runtime config tests

* Address channel connection review comments

* Use sha256 user buckets with legacy migration

* Ensure runtime IM channels are ready after restart

* Persist disconnected IM channel state

* Address channel connection review comments

* Address channel connection review findings

Frontend connect flow:
- Open the runtime-config dialog only when a provider still needs
  credentials; configured providers go straight to the connect flow, so
  the binding-code/deep-link path is reachable from the UI again.
- After saving credentials, continue into the connect flow when a user
  binding is still required (multi-user mode) instead of stopping at a
  "Connected" toast.
- Extract shared provider-state helpers to core/channels/provider-state
  and add unit + e2e coverage for the direct-connect and
  configure-then-connect paths.

Provider status semantics:
- Report connection_status from the user's newest connection row;
  with no binding it is not_connected, except in auth-disabled local
  mode where a configured running channel is effectively connected.

Concurrency and event-loop correctness:
- Offload ChannelRuntimeConfigStore construction and writes, channel
  service construction, and Slack connection replies to threads; add a
  tests/blocking_io/ anchor for the runtime-config handlers.
- Consume binding codes with a conditional UPDATE so a code can only be
  used once under concurrent workers; retry upsert_connection as an
  update when a concurrent insert wins the unique constraint.
- Serialize ensure_channel_ready per channel so concurrent provider
  polls cannot double-start a channel worker.

Config and migration hardening:
- Stop mutating the get_app_config()-cached Telegram provider config;
  the runtime store now owns the UI-entered bot username.
- Register channel_connections in STARTUP_ONLY_FIELDS with the
  standardized startup-only Field description.
- Match the legacy unsafe-id bucket by recomputing its exact SHA-1 name
  so another user's same-prefix bucket can never be migrated.
- Remove the unused Telegram process_webhook_update path and document
  src/core/channels in the frontend docs.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Address PR review comments on authz scoping and channel runtime

Security (review feedback from ShenAC-SAC):
- Scope internal-token callers to the connection owner carried in
  X-DeerFlow-Owner-User-Id instead of bypassing owner checks outright,
  in both require_permission(owner_check=True) and the stateless run
  endpoints. Internal callers keep access to their own and
  shared/legacy threads, and may claim a default-owned channel thread
  for its real owner, but a leaked internal token no longer grants
  cross-user thread access.
- Require admin privileges for POST/DELETE /api/channels/{provider}/
  runtime-config: runtime credentials and channel workers are
  instance-wide shared state (same model as the MCP config API).
  Read-only provider listing stays available to all users.

Performance (review feedback from willem-bd):
- Skip the redundant thread channel-metadata PATCH after the first
  successful backfill per thread.
- Reuse the per-connection Slack WebClient until its token changes
  instead of constructing one per outbound message.
- Reconcile channel readiness for all providers concurrently in
  GET /api/channels/providers.

Also resolve the code-quality unused-import flag in the blocking-io
anchor by pre-importing the channel service via importlib.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Fix prettier formatting in provider-state test

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Reconcile UI runtime channel config with config reload on restart

Main now reloads a channel's config.yaml entry on restart_channel()
(#3514, issue #3497). Adapt the user-owned connection flow to coexist:

- configure_channel() restarts with reload_config=False — the caller
  just supplied the authoritative config (browser-entered credentials
  that are never written to config.yaml), so a file reload must not
  clobber it with the stale on-disk entry.
- _load_channel_config() re-applies the UI runtime-store overlay used
  at startup, so an operator-triggered restart keeps browser-entered
  credentials for channels without a config.yaml entry and does not
  resurrect a channel disconnected from the UI.
- Offload the reload's disk IO (config.yaml + runtime store) with
  asyncio.to_thread, matching the blocking-IO policy on this branch.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

backend/tests/test_threads_router.py

@@ -1,4 +1,5 @@
 import re
+from types import SimpleNamespace
 from unittest.mock import patch
 
 import pytest
@@ -218,6 +219,37 @@ def test_create_thread_returns_iso_timestamps() -> None:
     assert body["created_at"] == body["updated_at"]
 
 
+def test_internal_owner_header_assigns_thread_to_owner() -> None:
+    import asyncio
+
+    from app.gateway.internal_auth import INTERNAL_OWNER_USER_ID_HEADER_NAME, INTERNAL_SYSTEM_ROLE
+
+    store = InMemoryStore()
+    checkpointer = InMemorySaver()
+    thread_store = MemoryThreadMetaStore(store)
+    request = SimpleNamespace(
+        headers={INTERNAL_OWNER_USER_ID_HEADER_NAME: "owner-1"},
+        state=SimpleNamespace(user=SimpleNamespace(id="default", system_role=INTERNAL_SYSTEM_ROLE)),
+        app=SimpleNamespace(state=SimpleNamespace(checkpointer=checkpointer, thread_store=thread_store)),
+    )
+
+    async def _scenario():
+        response = await threads.create_thread(
+            threads.ThreadCreateRequest(thread_id="channel-thread", metadata={}),
+            request,
+        )
+        owner_row = await thread_store.get("channel-thread", user_id="owner-1")
+        internal_row = await thread_store.get("channel-thread", user_id="default")
+        return response, owner_row, internal_row
+
+    response, owner_row, internal_row = asyncio.run(_scenario())
+
+    assert response.thread_id == "channel-thread"
+    assert owner_row is not None
+    assert owner_row["user_id"] == "owner-1"
+    assert internal_row is None
+
+
 def test_get_thread_returns_iso_for_legacy_unix_record() -> None:
     """A thread record written by older versions stores ``time.time()``
     floats. ``get_thread`` must transparently surface them as ISO so the