- test_background_review_does_not_narrow_toolset_schema: review fork must
NOT pass enabled_toolsets to AIAgent (full parent schema = matching
Anthropic cache key on the 'tools' field).
- test_background_review_installs_thread_local_whitelist: the runtime
whitelist that replaces schema-level narrowing must contain memory +
skills tools and exclude terminal / send_message / delegate_task /
web_search / execute_code.
- test_review_fork_inherits_parent_cached_system_prompt: new test for
PR #17276's first root cause — the fork's _cached_system_prompt must
equal the parent's byte-for-byte.
- test_review_fork_pins_session_start_and_session_id: defensive belt-and-
suspenders for the cached-prompt inheritance.
Inverted the original test_background_review_agent_uses_restricted_toolsets
(which asserted the schema-level narrowing) — that narrowing was the
direct cause of #25322's cache miss, and the runtime whitelist replaces
its safety claim without breaking cache parity.
Refs #25322, #15204, PR #17276.
