Critical fixes to salvaged PR #73020:
- Use SessionDB.append_message instead of raw INSERT INTO messages.
The original used wrong column names (session_key/created_at vs
session_id/timestamp) and bypassed FTS indexing, session metadata
updates, display_kind, and all other columns append_message handles.
- Use get_hermes_home() instead of hardcoded Path.home()/'.hermes'.
Profile-aware path resolution under HERMES_HOME override and active
profile isolation.
- Add 11 tests covering flush, recovery, serialisation, edge cases.
When FTS5 index corruption prevents INSERT INTO messages, the gateway
accumulates messages in _pending_messages (memory-only). On shutdown,
.clear() discards the only surviving copy — permanent user data loss.
Changes:
- Add gateway/shutdown_flush.py with flush_pending_to_file() and
recover_pending_to_db() for two-phase data preservation.
- Patch gateway/run.py: flush runner._pending_messages before clear()
in _stop_impl_body, and recover on startup after runner.start().
- Patch gateway/platforms/base.py: flush adapter._pending_messages
before clear() in the adapter shutdown path.
Recovery behavior:
- Reads pending JSON files from ~/.hermes/pending_messages/
- Inserts messages into state.db directly
- Per-session isolation: one corrupt session doesn't block others
- Successful recovery deletes the flush file
- Failed recovery re-saves for next startup retry
