fix: avoid treating Feishu file paths as commands (#1654)

Feishu channel classified any slash-prefixed text (including absolute
paths such as /mnt/user-data/...) as a COMMAND, causing them to be
misrouted through the command pipeline instead of the chat pipeline.

Fix by introducing a shared KNOWN_CHANNEL_COMMANDS frozenset in
app/channels/commands.py — the single authoritative source for the set
of supported slash commands.  Both the Feishu inbound parser and the
ChannelManager's unknown-command reply now derive from it, so adding
or removing a command requires only one edit.

Changes:
- app/channels/commands.py (new): defines KNOWN_CHANNEL_COMMANDS
- app/channels/feishu.py: replace local KNOWN_FEISHU_COMMANDS with the
  shared constant; _is_feishu_command() now gates on it
- app/channels/manager.py: import KNOWN_CHANNEL_COMMANDS and use it in
  the unknown-command fallback reply so the displayed list stays in sync
- tests/test_feishu_parser.py: parametrize over every entry in
  KNOWN_CHANNEL_COMMANDS (each must yield msg_type=command) and add
  parametrized chat cases for /unknown, absolute paths, etc.

Made with Cursor

Made-with: Cursor

Co-authored-by: Willem Jiang <willem.jiang@gmail.com>

backend/app/channels/commands.py

@@ -0,0 +1,20 @@
+"""Shared command definitions used by all channel implementations.
+
+Keeping the authoritative command set in one place ensures that channel
+parsers (e.g. Feishu) and the ChannelManager dispatcher stay in sync
+automatically — adding or removing a command here is the single edit
+required.
+"""
+
+from __future__ import annotations
+
+KNOWN_CHANNEL_COMMANDS: frozenset[str] = frozenset(
+    {
+        "/bootstrap",
+        "/new",
+        "/status",
+        "/models",
+        "/memory",
+        "/help",
+    }
+)