The 7.8 trace showed the completion loss was a sizer death spiral, not
expensive families: after two kills the budget fell to 3 sink visits and
never recovered, because portions finishing in 25-30 s sat under an assumed
70 s fixed start and read as "no information", so the budget could only
shrink.
- taint.sc streams each answer's own cost (`ms`); the backend carries it as a
reserved `__timing__` list through shards, partitions and reuse.
- The sizer budgets predicted seconds from per-family seconds-per-visit rates
learned from those costs, and measures the fixed start as the wall time the
answers do not explain (median), instead of assuming it.
- A kill names its culprit: the first unanswered id in request order. The ids
behind it never started and are re-queued at once; the culprit is asked
alone after the rest. One that still fails alone after more than a
portion's target is reported as `query_too_expensive`, apart from
`query_failed`.
- Portions grow id by id from the queue head, and a single-portion scan now
goes through the queue too, so a kill there re-asks its remainder.
- Fix: the reuse wrapper wrapped only `run_batch`, so since 7.8 every
portioned query bypassed the graph-reuse cache and its source-root
normalization. `run_batch_once` is wrapped too.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01EmM1j46qgKMh3zqD1QMwEo
