Review (Codex + 3-agent parallel) found the first cut of in-place mode was
incomplete: it only updated the system prompt, so the persisted transcript
stayed 'full history + summary' and the next turn/resume reloaded the full
history and immediately re-compacted (a loop), and every downstream layer
that keyed off session-id rotation silently no-op'd. The session_id was
doing double duty as the 'compaction happened' signal. This wires the whole
path so removing rotation is actually complete:
Agent (agent/conversation_compression.py):
- In-place now DURABLY replaces the transcript: replace_messages(session_id,
compressed) on the same row (the canonical store the gateway reloads from),
not just update_system_prompt. Resume reloads the compacted set; no loop.
- Reset flush identity/cursor (_last_flushed_db_idx=0, _flushed_db_message_ids
cleared) so next-turn appends diff against the compacted transcript.
- Expose a rotation-independent signal: agent._last_compaction_in_place, and
in_place=True on the session:compress event.
- Fire the compaction-boundary hooks (context-engine on_session_start, memory
manager on_session_switch, reason='compression') in BOTH modes — in-place
passes the same id as parent so DAG/buffer state still checkpoints. Without
this, memory/context plugins miss every in-place compaction.
Gateway auto-compress (gateway/run.py):
- Read agent._last_compaction_in_place; set history_offset=0 on rotation OR
in-place (both return the compacted set, so slicing past the pre-compaction
length would drop everything). Carry compacted_in_place in the result dict.
- No extra rewrite needed: the agent shares the gateway's SessionDB, so its
replace_messages already updated the canonical store load_transcript reads.
Manual /compress (gateway/slash_commands.py):
- The throwaway /compress agent has no _session_db, so rewrite_transcript is
the durable write. Previously gated behind 'if rotated:' which treated
'id unchanged' as the #44794 data-loss failure case and SKIPPED the rewrite
— making /compress a silent no-op in in-place mode. Now rewrites on rotated
OR in_place; the data-loss guard still fires only for the genuine
no-rotation-AND-not-in-place failure.
Hygiene auto-compress already writes _compressed to the same id
unconditionally (its agent has no _session_db, can't rotate) — correct for
in-place, no change.
Tests (tests/run_agent/test_in_place_compaction.py):
- Assert the DURABLE transcript IS the compacted set after reload
(get_messages_as_conversation == compacted), message_count==2, flush
identity reset, and the rotation-independent signal set on in-place /
unset on rotation. Rotation regression guard unchanged.
Verified: 64 tests green across in-place + rotation/persistence/boundary/
concurrent/failure-sync/command/cli suites; E2E both modes (durable replace,
gateway offset=0, rotation preserves old transcript); ruff clean. Still
default-off.
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