fix(desktop): discover MCP tools for dashboard /api/ws backends (#44512)

The desktop chat surface talks to the dashboard's in-process /api/ws
gateway, which builds agents through tui_gateway.server._make_agent. That
path only snapshots the existing tool registry — MCP discovery is started
by tui_gateway/entry.py (the stdio TUI), which the dashboard process never
runs. So a profile's configured MCP servers never connect under the
desktop app and sessions show no MCP tools.

Start a shared background MCP discovery thread at dashboard startup (via
hermes_cli.mcp_startup, bounded so a slow/dead server can't block boot),
and have _make_agent briefly join that thread in addition to the existing
entry-owned TUI thread before snapshotting tools.

Carved out of #44478.

Co-authored-by: AJ <yspdev@gmail.com>

hermes_cli/main.py

@@ -10431,6 +10431,26 @@ def cmd_dashboard(args):
         # the missing-provider state if it matters.
         print(f"⚠ Plugin discovery failed: {exc}", file=sys.stderr)
 
+    # Desktop chat uses the dashboard's in-process /api/ws gateway, which builds
+    # agents via tui_gateway.server._make_agent.  That path only snapshots the
+    # tool registry — it never starts MCP discovery (the stdio TUI does that in
+    # tui_gateway/entry.py, which the dashboard process doesn't run).  Without
+    # this, a profile's configured MCP servers never connect, so desktop
+    # sessions show no MCP tools.  Spawn discovery in the background here so a
+    # slow/dead server can't block dashboard startup.
+    try:
+        from hermes_cli.mcp_startup import start_background_mcp_discovery
+
+        start_background_mcp_discovery(
+            logger=logger,
+            thread_name="dashboard-mcp-discovery",
+        )
+    except Exception:
+        logger.debug(
+            "Background MCP tool discovery failed at dashboard startup",
+            exc_info=True,
+        )
+
     from hermes_cli.web_server import start_server
 
     # The in-browser Chat tab (the embedded TUI over PTY/WebSocket) is always

tests/hermes_cli/test_dashboard_unified_launch.py

@@ -128,3 +128,45 @@ class TestUnifiedDashboardRouting:
         with pytest.raises((SystemExit, AttributeError, ImportError, TypeError)):
             main_mod.cmd_dashboard(_args(open_profile="worker_x"))
         assert execs == []
+
+    def test_dashboard_starts_mcp_discovery_for_ws_backend(self, main_mod, monkeypatch):
+        """The dashboard process serves the /api/ws gateway but never runs
+        tui_gateway/entry.py, so it must kick off MCP discovery itself or
+        desktop sessions never see a profile's MCP tools."""
+        monkeypatch.setattr(
+            "hermes_cli.profiles.get_active_profile_name", lambda: "default"
+        )
+        monkeypatch.delenv("HERMES_WEB_DIST", raising=False)
+        monkeypatch.setattr(main_mod, "_sync_bundled_skills_quietly", lambda: None)
+        monkeypatch.setattr(main_mod, "_build_web_ui", lambda *_a, **_k: True)
+        monkeypatch.setitem(sys.modules, "fastapi", types.SimpleNamespace())
+        monkeypatch.setitem(sys.modules, "uvicorn", types.SimpleNamespace())
+        monkeypatch.setitem(
+            sys.modules,
+            "hermes_logging",
+            types.SimpleNamespace(setup_logging=lambda **_k: None),
+        )
+        monkeypatch.setitem(
+            sys.modules,
+            "hermes_cli.plugins",
+            types.SimpleNamespace(discover_plugins=lambda: None),
+        )
+        calls = []
+        monkeypatch.setattr(
+            "hermes_cli.mcp_startup.start_background_mcp_discovery",
+            lambda **kwargs: calls.append(kwargs),
+        )
+        monkeypatch.setitem(
+            sys.modules,
+            "hermes_cli.web_server",
+            types.SimpleNamespace(start_server=lambda **_kwargs: None),
+        )
+
+        main_mod.cmd_dashboard(_args())
+
+        assert calls == [
+            {
+                "logger": main_mod.logger,
+                "thread_name": "dashboard-mcp-discovery",
+            }
+        ]

tests/test_tui_gateway_server.py

@@ -6096,6 +6096,24 @@ def test_make_agent_reads_nested_max_turns(monkeypatch):
     assert mock_agent.call_args.kwargs["max_iterations"] == 200
 
 
+def test_make_agent_waits_for_shared_mcp_discovery(monkeypatch):
+    _setup_make_agent_mocks(monkeypatch, {})
+    waited = []
+
+    from hermes_cli import mcp_startup
+
+    monkeypatch.setattr(
+        mcp_startup,
+        "wait_for_mcp_discovery",
+        lambda timeout=0.75: waited.append(timeout),
+    )
+
+    with patch("run_agent.AIAgent"):
+        server._make_agent("sid1", "key1")
+
+    assert waited == [0.75]
+
+
 def test_make_agent_nested_max_turns_takes_priority(monkeypatch):
     _setup_make_agent_mocks(
         monkeypatch, {"agent": {"max_turns": 500}, "max_turns": 100}

tui_gateway/server.py

@@ -3072,11 +3072,17 @@ def _make_agent(
     from hermes_cli.runtime_provider import resolve_runtime_provider
 
     # MCP tool discovery runs in a background daemon thread at startup so a
-    # dead server can't freeze the shell (see tui_gateway/entry.py).  The agent
-    # snapshots its tool list once here and never re-reads it, so briefly wait
-    # for in-flight discovery to land before building — bounded, so a slow/dead
-    # server still can't block.  No-op once discovery has finished (every build
-    # after the first during a slow startup).
+    # dead server can't freeze the shell.  The agent snapshots its tool list
+    # once here and never re-reads it, so briefly wait for in-flight discovery
+    # to land before building — bounded, so a slow/dead server still can't
+    # block. Dashboard /api/ws uses hermes_cli.mcp_startup; TUI stdio keeps
+    # its existing tui_gateway.entry-owned thread.
+    try:
+        from hermes_cli.mcp_startup import wait_for_mcp_discovery
+
+        wait_for_mcp_discovery()
+    except Exception:
+        pass
     try:
         from tui_gateway.entry import wait_for_mcp_discovery