Fix local MCP URL after port fallback

backend/app/assistant_tools.py

@@ -16,7 +16,26 @@
 MAX_FILE_LINES = 120
 MAX_SEARCH_RESULTS = 12
 BLOCKED_NAMES = {".env", ".git", ".ssh", "id_rsa", "id_ed25519"}
-DEFAULT_MCP_URL = "http://127.0.0.1:3000/mcp/"
+
+
+def _local_mcp_url() -> str:
+    """Return this process's local MCP endpoint.
+
+    ``orbit run`` may select a port above the requested one when it is already
+    occupied. It passes that selected port through ``ORBIT_PORT`` to keep
+    generated MCP configuration from pointing at the process that occupied it.
+    """
+    configured_port = os.environ.get("ORBIT_PORT", "3000").strip()
+    try:
+        port = int(configured_port)
+    except ValueError:
+        port = 3000
+    if not 1 <= port <= 65535:
+        port = 3000
+    return f"http://127.0.0.1:{port}/mcp/"
+
+
+DEFAULT_MCP_URL = _local_mcp_url()
 
 
 def _terminal_visible() -> bool:

backend/tests/test_assistant_graph.py

@@ -1,3 +1,4 @@
+from app import assistant_tools
 from app.assistant_graph import DEFAULT_MCP_URL, LocalMcpTools, OrbitAssistantGraph, build_assistant_prompt
 from app.providers import ModelSettings
 
@@ -56,6 +57,15 @@ def test_assistant_prompt_uses_local_mcp_as_the_control_room_source_of_truth():
     assert "Assistant: Earlier answer" in prompt
 
 
+def test_local_mcp_url_uses_the_effective_server_port(monkeypatch):
+    monkeypatch.setenv("ORBIT_PORT", "3001")
+
+    assert assistant_tools._local_mcp_url() == "http://127.0.0.1:3001/mcp/"
+
+    monkeypatch.setenv("ORBIT_PORT", "not-a-port")
+    assert assistant_tools._local_mcp_url() == "http://127.0.0.1:3000/mcp/"
+
+
 def test_assistant_prompt_prioritizes_ui_tools_for_browser_ui_requests():
     prompt = build_assistant_prompt("What screen is open?", [], "en", ui_enabled=True)
 

bin/orbit.mjs

@@ -67,6 +67,7 @@ if (!Number.isInteger(requestedPort) || requestedPort < 1 || requestedPort > 655
 const port = await nextAvailablePort(requestedPort, host)
 const localUrl = `http://127.0.0.1:${port}`
 console.log(`OpenOrbit is starting. Open ${localUrl}`)
+console.log(`MCP endpoint: ${localUrl}/mcp/`)
 if (port !== requestedPort) {
   console.log(`Port ${requestedPort} is in use; using ${port} instead.`)
 }
@@ -76,7 +77,9 @@ if (process.env.ORBIT_PUBLIC_URL) {
 const server = spawn(venvPython, ['-m', 'uvicorn', 'app.main:app', '--app-dir', 'backend', '--host', host, '--port', port], {
   cwd: root,
   stdio: 'inherit',
-  env: { ...process.env, ...(appData ? { ORBIT_APP_DATA: appData } : {}) },
+  // Keep the server's generated local MCP configuration aligned with the
+  // port selected above when the requested port was already occupied.
+  env: { ...process.env, ORBIT_PORT: String(port), ...(appData ? { ORBIT_APP_DATA: appData } : {}) },
 })
 process.on('SIGINT', () => server.kill('SIGINT'))
 process.on('SIGTERM', () => server.kill('SIGTERM'))