Bundles:
- #1370 fix: expose session lineage metadata in API (@dso2ng)
Pre-release fixes applied:
1) Perf: replaced full table scan with parameterized WHERE id IN (...)
query. Original code did SELECT id, parent_session_id, end_reason
FROM sessions on every sidebar refresh. Measured 9ms cached scan at
1000 rows in production (up to ~450ms cold-cache); scales linearly.
New approach hits PRIMARY KEY + idx_sessions_parent — 50x faster
at 1000 rows, ~0.2ms regardless of total row count. Depth-bounded
to 20 hops to cap query count under pathological data.
2) Orphan-parent guard: suppress parent_session_id in API output when
the referenced parent row doesn't exist in state.db. The frontend's
#1358 _sessionLineageKey falls through to parent_session_id when
_lineage_root_id is missing — orphan references would create
never-collapsing single-row groups in the sidebar.
3) Regression suite (5 tests in
test_pr1370_lineage_metadata_perf_and_orphan.py):
- Pins the no-full-scan invariant by intercepting all SQL queries
and asserting no SELECT FROM sessions without a WHERE clause
- Pins orphan-parent suppression
- Pins cycle termination via threading.Event watchdog (2s timeout)
- End-to-end test for 4-segment compression chain root resolution
- Pins non-compression end_reason boundary stops walk
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