Phase 2c mutation-check found the salvaged tests covered only the pure helpers
(_is_background_review_harness_message / _strip_background_review_harness) — the
two integration WIRINGS had zero coverage: removing the _persist_disabled guard
in _flush_messages_to_session_db, or the _strip call in
get_messages_as_conversation, left all 13 tests green.
Add:
- TestPersistDisabledHardStop: a _persist_disabled agent's flush writes nothing
to a live SessionDB (guards the run_agent hard-stop).
- TestGetMessagesAsConversationStripsHarness: a session with stray harness rows
resumes clean end-to-end through get_messages_as_conversation (guards the
hermes_state load-time wiring).
Mutation-checked: each new test fails when its wiring is reverted.
The forked skill/memory review agent shares the parent's session_id for
prompt-cache warmth. Without isolation it wrote its harness turn ('Review the
conversation above and update the skill library…') plus its curator-mode reply
straight into the user's REAL session in state.db; the next live turn re-read
that injected user message as a standing instruction and the agent 'became' the
curator, refusing the actual task.
Root fix: a _persist_disabled flag on the fork that hard-stops every DB write
and lazy-open path (_flush_messages_to_session_db, _ensure_db_session,
_get_session_db_for_recall) — the review writes only to the skill/memory stores
via its tools. Defense-in-depth: _strip_background_review_harness drops any
stray harness message (and the assistant reply that followed) at load time in
get_messages_as_conversation, so an already-polluted session resumes clean.
Salvaged from #50296.
Co-authored-by: arminanton <29869547+arminanton@users.noreply.github.com>
