fix(acp): wire approval callback + make it thread-local (#13525)

Two related ACP approval issues:

GHSA-96vc-wcxf-jjff — ACP's _run_agent never set HERMES_INTERACTIVE
(or any other flag recognized by tools.approval), so check_all_command_guards
took the non-interactive auto-approve path and never consulted the
ACP-supplied approval callback (conn.request_permission). Dangerous
commands executed in ACP sessions without operator approval despite
the callback being installed. Fix: set HERMES_INTERACTIVE=1 around
the agent run so check_all_command_guards routes through
prompt_dangerous_approval(approval_callback=...) — the correct shape
for ACP's per-session request_permission call. HERMES_EXEC_ASK would
have routed through the gateway-queue path instead, which requires a
notify_cb registered in _gateway_notify_cbs (not applicable to ACP).

GHSA-qg5c-hvr5-hjgr — _approval_callback and _sudo_password_callback
were module-level globals in terminal_tool. Concurrent ACP sessions
running in ThreadPoolExecutor threads each installed their own callback
into the same slot, racing. Fix: store both callbacks in threading.local()
so each thread has its own slot. CLI mode (single thread) is unaffected;
gateway mode uses a separate queue-based approval path and was never
touched.

set_approval_callback is now called INSIDE _run_agent (the executor
thread) rather than before dispatching — so the TLS write lands on the
correct thread.

Tests: 5 new in tests/acp/test_approval_isolation.py covering
thread-local isolation of both callbacks and the HERMES_INTERACTIVE
callback routing. Existing tests/acp/ (159 tests) and tests/tools/
approval-related tests continue to pass.

Fixes GHSA-96vc-wcxf-jjff
Fixes GHSA-qg5c-hvr5-hjgr

acp_adapter/server.py

@@ -4,6 +4,7 @@ from __future__ import annotations
 
 import asyncio
 import logging
+import os
 from collections import defaultdict, deque
 from concurrent.futures import ThreadPoolExecutor
 from typing import Any, Deque, Optional
@@ -554,15 +555,32 @@ class HermesACPAgent(acp.Agent):
         agent.step_callback = step_cb
         agent.message_callback = message_cb
 
-        if approval_cb:
-            try:
-                from tools import terminal_tool as _terminal_tool
-                previous_approval_cb = getattr(_terminal_tool, "_approval_callback", None)
-                _terminal_tool.set_approval_callback(approval_cb)
-            except Exception:
-                logger.debug("Could not set ACP approval callback", exc_info=True)
+        # Approval callback is per-thread (thread-local, GHSA-qg5c-hvr5-hjgr).
+        # Set it INSIDE _run_agent so the TLS write happens in the executor
+        # thread — setting it here would write to the event-loop thread's TLS,
+        # not the executor's. Also set HERMES_INTERACTIVE so approval.py
+        # takes the CLI-interactive path (which calls the registered
+        # callback via prompt_dangerous_approval) instead of the
+        # non-interactive auto-approve branch (GHSA-96vc-wcxf-jjff).
+        # ACP's conn.request_permission maps cleanly to the interactive
+        # callback shape — not the gateway-queue HERMES_EXEC_ASK path,
+        # which requires a notify_cb registered in _gateway_notify_cbs.
+        previous_approval_cb = None
+        previous_interactive = None
 
         def _run_agent() -> dict:
+            nonlocal previous_approval_cb, previous_interactive
+            if approval_cb:
+                try:
+                    from tools import terminal_tool as _terminal_tool
+                    previous_approval_cb = _terminal_tool._get_approval_callback()
+                    _terminal_tool.set_approval_callback(approval_cb)
+                except Exception:
+                    logger.debug("Could not set ACP approval callback", exc_info=True)
+            # Signal to tools.approval that we have an interactive callback
+            # and the non-interactive auto-approve path must not fire.
+            previous_interactive = os.environ.get("HERMES_INTERACTIVE")
+            os.environ["HERMES_INTERACTIVE"] = "1"
             try:
                 result = agent.run_conversation(
                     user_message=user_text,
@@ -574,6 +592,11 @@ class HermesACPAgent(acp.Agent):
                 logger.exception("Agent error in session %s", session_id)
                 return {"final_response": f"Error: {e}", "messages": state.history}
             finally:
+                # Restore HERMES_INTERACTIVE.
+                if previous_interactive is None:
+                    os.environ.pop("HERMES_INTERACTIVE", None)
+                else:
+                    os.environ["HERMES_INTERACTIVE"] = previous_interactive
                 if approval_cb:
                     try:
                         from tools import terminal_tool as _terminal_tool