hermes - 💡(How to fix) Fix _last_resolved_tool_names global causes race condition in concurrent sessions

Bug: _last_resolved_tool_names Global Race Condition

Severity: HIGH
File: model_tools.py:212
Affected versions: v0.14.0 (and likely all prior)

Problem

_last_resolved_tool_names is a module-level List[str] — not per-session, not per-agent-instance. When two sessions run concurrently in the same gateway process (e.g., two Feishu/Telegram users messaging simultaneously from different chats), each session's get_tool_definitions() overwrites this global:

# model_tools.py:212
_last_resolved_tool_names: list = []  # process-global!

Race scenario:

1. Session A calls get_tool_definitions() → sets _last_resolved_tool_names = [A's tools]
2. Session B calls get_tool_definitions() → overwrites _last_resolved_tool_names = [B's tools]
3. Session A calls handle_function_call("terminal") → checks B's tool list → may reject A's tool call as "not available"

Existing Mitigation (Insufficient)

delegate_tool.py saves and restores _last_resolved_tool_names around subagent execution, but this only covers the delegation chain within a single session — not concurrent top-level sessions.

Impact

• Tool calls may be incorrectly rejected with "tool not available" errors
• The race window is small (tool list is set at run_conversation() start and typically stable), but real
• More likely when sessions have different toolsets enabled

Suggested Fixes

Option A (Best): Convert to ContextVar[List[str]] — each asyncio task gets automatic isolation:

_last_resolved_tool_names: ContextVar[list] = ContextVar("_last_resolved_tool_names", default=[])

Option B: Store as per-AIAgent instance attribute (self._resolved_tool_names) and pass through handle_function_call().

Option C: Convert to Dict[str, List[str]] keyed by session_key.

Reproduction

1. Start gateway with a messaging platform (Feishu/Telegram/Discord)
2. Two users send messages simultaneously from different chats with different toolset configurations
3. Check logs for spurious "tool not available" rejections

Environment

• Hermes Agent v0.14.0 (tag v2026.5.16)
• 10 profiles running concurrently
• Feishu WebSocket platform