fix: use session_key instead of chat_id for adapter interrupt lookups

* fix: use session_key instead of chat_id for adapter interrupt lookups

monitor_for_interrupt() in _run_agent was using source.chat_id to query
the adapter's has_pending_interrupt() and get_pending_message() methods.
But the adapter stores interrupt events under build_session_key(source),
which produces a different string (e.g. 'agent:main:telegram:dm' vs '123456').

This key mismatch meant the interrupt was never detected through the
adapter path, which is the only active interrupt path for all adapter-based
platforms (Telegram, Discord, Slack, etc.). The gateway-level interrupt
path (in dispatch_message) is unreachable because the adapter intercepts
the 2nd message in handle_message() before it reaches dispatch_message().

Result: sending a new message while subagents were running had no effect —
the interrupt was silently lost.

Fix: replace all source.chat_id references in the interrupt-related code
within _run_agent() with the session_key parameter, which matches the
adapter's storage keys.

Also adds regression tests verifying session_key vs chat_id consistency.

* debug: add file-based logging to CLI interrupt path

Temporary instrumentation to diagnose why message-based interrupts
don't seem to work during subagent execution. Logs to
~/.hermes/interrupt_debug.log (immune to redirect_stdout).

Two log points:
1. When Enter handler puts message into _interrupt_queue
2. When chat() reads it and calls agent.interrupt()

This will reveal whether the message reaches the queue and
whether the interrupt is actually fired.

tests/gateway/test_interrupt_key_match.py

@@ -0,0 +1,124 @@
+"""Tests verifying interrupt key consistency between adapter and gateway.
+
+Regression test for a bug where monitor_for_interrupt() in _run_agent used
+source.chat_id to query the adapter, but the adapter stores interrupts under
+the full session key (build_session_key output).  This mismatch meant
+interrupts were never detected, causing subagents to ignore new messages.
+"""
+
+import asyncio
+
+import pytest
+
+from gateway.config import Platform, PlatformConfig
+from gateway.platforms.base import BasePlatformAdapter, MessageEvent, SendResult
+from gateway.session import SessionSource, build_session_key
+
+
+class StubAdapter(BasePlatformAdapter):
+    """Minimal adapter for interrupt tests."""
+
+    def __init__(self):
+        super().__init__(PlatformConfig(enabled=True, token="test"), Platform.TELEGRAM)
+
+    async def connect(self):
+        return True
+
+    async def disconnect(self):
+        pass
+
+    async def send(self, chat_id, content, reply_to=None, metadata=None):
+        return SendResult(success=True, message_id="1")
+
+    async def send_typing(self, chat_id, metadata=None):
+        pass
+
+    async def get_chat_info(self, chat_id):
+        return {"id": chat_id}
+
+
+def _source(chat_id="123456", chat_type="dm", thread_id=None):
+    return SessionSource(
+        platform=Platform.TELEGRAM,
+        chat_id=chat_id,
+        chat_type=chat_type,
+        thread_id=thread_id,
+    )
+
+
+class TestInterruptKeyConsistency:
+    """Ensure adapter interrupt methods are queried with session_key, not chat_id."""
+
+    def test_session_key_differs_from_chat_id_for_dm(self):
+        """Session key for a DM is NOT the same as chat_id."""
+        source = _source("123456", "dm")
+        session_key = build_session_key(source)
+        assert session_key != source.chat_id
+        assert session_key == "agent:main:telegram:dm"
+
+    def test_session_key_differs_from_chat_id_for_group(self):
+        """Session key for a group chat includes prefix, unlike raw chat_id."""
+        source = _source("-1001234", "group")
+        session_key = build_session_key(source)
+        assert session_key != source.chat_id
+        assert "agent:main:" in session_key
+        assert source.chat_id in session_key
+
+    @pytest.mark.asyncio
+    async def test_has_pending_interrupt_requires_session_key(self):
+        """has_pending_interrupt returns True only when queried with session_key."""
+        adapter = StubAdapter()
+        source = _source("123456", "dm")
+        session_key = build_session_key(source)
+
+        # Simulate adapter storing interrupt under session_key
+        interrupt_event = asyncio.Event()
+        adapter._active_sessions[session_key] = interrupt_event
+        interrupt_event.set()
+
+        # Using session_key → found
+        assert adapter.has_pending_interrupt(session_key) is True
+
+        # Using chat_id → NOT found (this was the bug)
+        assert adapter.has_pending_interrupt(source.chat_id) is False
+
+    @pytest.mark.asyncio
+    async def test_get_pending_message_requires_session_key(self):
+        """get_pending_message returns the event only with session_key."""
+        adapter = StubAdapter()
+        source = _source("123456", "dm")
+        session_key = build_session_key(source)
+
+        event = MessageEvent(text="hello", source=source, message_id="42")
+        adapter._pending_messages[session_key] = event
+
+        # Using chat_id → None (the bug)
+        assert adapter.get_pending_message(source.chat_id) is None
+
+        # Using session_key → found
+        result = adapter.get_pending_message(session_key)
+        assert result is event
+
+    @pytest.mark.asyncio
+    async def test_handle_message_stores_under_session_key(self):
+        """handle_message stores pending messages under session_key, not chat_id."""
+        adapter = StubAdapter()
+        adapter.set_message_handler(lambda event: asyncio.sleep(0, result=None))
+
+        source = _source("-1001234", "group")
+        session_key = build_session_key(source)
+
+        # Mark session as active
+        adapter._active_sessions[session_key] = asyncio.Event()
+
+        # Send a second message while session is active
+        event = MessageEvent(text="interrupt!", source=source, message_id="2")
+        await adapter.handle_message(event)
+
+        # Stored under session_key
+        assert session_key in adapter._pending_messages
+        # NOT stored under chat_id
+        assert source.chat_id not in adapter._pending_messages
+
+        # Interrupt event was set
+        assert adapter._active_sessions[session_key].is_set()