qin-chenghan 60e50537f3
fix(subagents): prohibit task tool in general-purpose system prompt (#4161)
* fix(subagents): prohibit task tool in general-purpose system prompt (#4159)

The general-purpose subagent correctly lists `task` in disallowed_tools
to prevent recursive nesting. However, the system prompt did not
explicitly tell the LLM that `task` is unavailable. When the subagent
sees the parent agent use `task`, it infers the tool is available and
attempts to call it, triggering a LangGraph tool validation error.

Add an explicit <tool_restrictions> block to the system prompt stating
that `task` is NOT available and the subagent must NEVER attempt to
call it. This prevents the LLM from attempting the call in the first
place, rather than relying on runtime rejection.

Add a regression test verifying the prompt contains the prohibition.

* fix(security): register tool_restrictions in input sanitization denylist

PR #4161 added <tool_restrictions> to general_purpose.py subagent prompt
but did not register it in _BLOCKED_TAG_NAMES. The anti-drift test
test_denylist_covers_framework_authority_blocks caught this: forging
<tool_restrictions> in untrusted input could trick the model into
believing it has (or lacks) tool restrictions it does not.

Add 'tool_restrictions' to _BLOCKED_TAG_NAMES alongside the other
subagent authority blocks (file_editing_workflow / guidelines /
output_format / working_directory).
2026-07-14 22:51:21 +08:00
..