* fix(sessions): resolve branchy compression lineage to the freshest tip (#3751)
Compression parents can have multiple continuation-looking children when a stale
segment is resumed after a newer compressed branch already exists. The previous
projection followed the newest DIRECT child only, so it could hide the deeper
branch with the latest real activity and make a conversation look missing/stale
after compaction or session rotation.
- compression_tip() now walks ALL reachable continuation descendants (DFS) and
selects the freshest importable (messageful) tip by (last_activity, depth).
- read_session_lineage_metadata() expands descendants from the materialized
ancestors via the parent index (scoped, 20-hop cap), pulls per-session message
stats from the messages table, and exposes a canonical _lineage_tip_id so the
WebUI sidebar collapse picks the same tip as the projection.
Backward-compat hardening (two release-gate Codex findings, both fixed + tested):
The new message-stats / tip-scoring code must not raise on older/minimal or
non-standard state.db schemas, which previously collapsed the whole projection:
- messages table with NO `timestamp` column → MAX(timestamp) raised in SQL →
read_session_lineage_metadata returned {} (lost all lineage metadata).
- ISO-8601 TEXT messages.timestamp → float()/raw comparison raised TypeError;
in read_importable_agent_session_rows that propagated through compression_tip
and get_cli_sessions() swallowed it, hiding ALL imported agent rows.
Fixes:
- PRAGMA table_info(messages) detection: require session_id, only SELECT
MAX(timestamp) when present (else NULL + COUNT only); fall back to message_count.
- new _as_score() helper (first numerically-coercible value, else next
candidate e.g. started_at) used at EVERY tip-scoring / sort site in both
compression_tip() and freshest_continuation_tip(), plus the projection sort.
- regression tests: lineage metadata survives REAL/absent/TEXT messages.timestamp,
and read_importable_agent_session_rows survives a TEXT timestamp (no empty hide).
Co-authored-by: ai-ag2026 <[email protected]>
* docs(changelog): stamp v0.51.306 — Release JV (stage-a2 #3751)
---------
Co-authored-by: nesquena-hermes <[email protected]>
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