feat(server): add spawn constants to context.py

amc_server/context.py

@@ -1,3 +1,4 @@
+import secrets
 import shutil
 from pathlib import Path
 import threading
@@ -68,3 +69,49 @@ _DISMISSED_MAX = 500
 
 # Serialize state collection because it mutates session files/caches.
 _state_lock = threading.Lock()
+
+# Projects directory for spawning agents
+PROJECTS_DIR = Path.home() / 'projects'
+
+# Default Zellij session for spawning
+ZELLIJ_SESSION = 'infra'
+
+# Lock for serializing spawn operations (prevents Zellij race conditions)
+_spawn_lock = threading.Lock()
+
+# Rate limiting: track last spawn time per project (prevents spam)
+_spawn_timestamps: dict[str, float] = {}
+SPAWN_COOLDOWN_SEC = 10.0
+
+# Auth token for spawn endpoint
+_auth_token: str = ''
+
+
+def generate_auth_token():
+    """Generate a one-time auth token for this server instance."""
+    global _auth_token
+    _auth_token = secrets.token_urlsafe(32)
+    return _auth_token
+
+
+def validate_auth_token(request_token: str) -> bool:
+    """Validate the Authorization header token."""
+    return request_token == f'Bearer {_auth_token}'
+
+
+def start_projects_watcher():
+    """Start background thread to refresh projects cache every 5 minutes."""
+    import logging
+    from amc_server.mixins.spawn import load_projects_cache
+
+    def _watch_loop():
+        import time
+        while True:
+            try:
+                time.sleep(300)
+                load_projects_cache()
+            except Exception:
+                logging.exception('Projects cache refresh failed')
+
+    thread = threading.Thread(target=_watch_loop, daemon=True)
+    thread.start()