Shared app servers: the PreToolUse hook leaves a ticket naming the calling session, the MCP server takes it per call (middleware), so two sessions of one app on one Harbor server act as themselves; i_am checks instead of binding and is allowed under a stop

harbor/sessions.py

@@ -0,0 +1,51 @@
+"""Which agent made this MCP call, when one app runs several sessions (Codex and Codex2) on one shared Harbor server.
+
+An app starts one Harbor MCP server and shares it between its sessions, so the server cannot tell them apart. The
+app's PreToolUse hook can: it runs before every tool call with the session's working folder. So the hook leaves a
+ticket (app, tool, arguments, agent) and the server takes the matching ticket when the call arrives - oldest first,
+within two minutes. Without a ticket (hooks not installed or not trusted) the server falls back to its own identity."""
+import json
+import time
+
+SCHEMA = """
+CREATE TABLE IF NOT EXISTS session_tickets(id INTEGER PRIMARY KEY, host TEXT NOT NULL, tool TEXT NOT NULL,
+    args TEXT NOT NULL, agent TEXT NOT NULL, at REAL NOT NULL, used INTEGER NOT NULL DEFAULT 0);
+CREATE INDEX IF NOT EXISTS session_tickets_open ON session_tickets(host, tool, used, at);
+"""
+MAX_AGE = 120.0
+
+
+def args_key(args):
+    return json.dumps(args or {}, sort_keys=True, separators=(",", ":"), default=str)
+
+
+def leave(harbor, host, tool, args, agent, now=None):
+    now = time.time() if now is None else now
+
+    def do(c):
+        c.execute("DELETE FROM session_tickets WHERE at < ?", (now - 10 * MAX_AGE,))
+        c.execute("INSERT INTO session_tickets(host, tool, args, agent, at) VALUES (?,?,?,?,?)",
+                  (host or "", tool, args_key(args), agent, now))
+    ensure(harbor)
+    harbor._write(do)
+
+
+def take(harbor, host, tool, args, now=None):
+    """The agent whose hook announced this exact call, or None."""
+    now = time.time() if now is None else now
+    ensure(harbor)
+
+    def do(c):
+        row = c.execute("SELECT id, agent FROM session_tickets WHERE host=? AND tool=? AND args=? AND used=0 AND at>=? "
+                        "ORDER BY at, id LIMIT 1", (host or "", tool, args_key(args), now - MAX_AGE)).fetchone()
+        if not row:
+            return None
+        c.execute("UPDATE session_tickets SET used=1 WHERE id=?", (row[0],))
+        return row[1]
+    return harbor._write(do)
+
+
+def ensure(harbor):
+    if not getattr(harbor, "_session_tickets_ready", False):
+        harbor.conn.executescript(SCHEMA)
+        harbor._session_tickets_ready = True