| 2026-06-05 | `bf5a861` | Rebuild changed daily aggregate buckets from time-ranged versions. | Confirmed on two full-profile repeated captures with `buildFingerprint: 1.0(1)-1780640325-92064`. The overnight-data run completed in `21.8s` with `127/127` complete, `CaptureModes: unchangedDelta=111, delta=16`, and `DeltaEvents: 322`; daily aggregate rebuild dropped from `6.9s` to `0.0s`, with daily aggregate work now only `0.6s` copy. The low-delta run completed in `6.6s` with `CaptureModes: unchangedDelta=125, delta=2`; daily aggregate rebuild again stayed `0.0s`. Conclusion: the time-ranged `sample_versions(start_date, sample_id)` query solved the affected-bucket rebuild bottleneck. Continue monitoring first-import insert timing because the new index is a write-path tradeoff. |

 | 2026-06-05 | `e7d45a2` | Count observation events from the event table first. | Confirmed on a full-profile repeated capture with `buildFingerprint: 1.0(1)-1780646299-92064`: wall clock `15.6s`, `127/127` complete, `CaptureModes: unchangedDelta=114, delta=13`, and `DeltaEvents: 99`. `SummedFinalizeEventCountElapsed` dropped from the post-`bf5a861` overnight baseline `2.5s` to `0.0s`; total finalize dropped to `1.7s`, while daily aggregate rebuild stayed `0.0s`. Remaining cost is processing: `9.1s` total, led by Heart Rate `4.6s` for `18` events, Active Energy `1.8s` for `11` events, and Basal Energy `1.5s` for `5` events. |

 | 2026-06-05 | `cfd9de8` | Split processing timing diagnostics. | Confirmed on a full-profile repeated capture with `buildFingerprint: 1.0(1)-1780683224-92064`: wall clock `14.7s`, `127/127` complete, `CaptureModes: unchangedDelta=120, delta=7`, and `DeltaEvents: 11`. `SummedProcessingElapsed` was `8.5s` and `SummedProcessingRecordArchiveRebuildElapsed` was also `8.5s`; delta apply, initial record processing, record archive finalization, and processing other all rounded to `0.0s`. Per-type rebuild cost dominated changed high-volume metrics: Heart Rate `4.4s`, Active Energy `1.7s`, Basal Energy `1.5s`, Steps `0.4s`, and Walking + Running Distance `0.4s`. Conclusion: the repeated-capture bottleneck is no longer SQLite finalization; it is the legacy compact `recordArchiveData` rebuild for changed types. |

 ## Current Diagnosis

   rebuild for SQLite-backed deltas: repeated full-profile wall clock dropped to

   `6.2s`, `SummedProcessingElapsed` dropped to `0.0s`, and changed high-volume

   metrics such as Heart Rate and Active Energy completed in about `0.2s`.

 - A large older-build first import on an `8.4M`-record database completed but

   took `166m10s`, with `137m31s` summed insert time. This confirms that full

   authorized backup volume can be much larger than the original 15-type test

    identity unless the build provenance is otherwise certain. `sourceCommit`

    and `sourceDirty` are useful when present, but may be `unknown` for normal

    Xcode test installs.

 9. Keep watching first-import insert timing on the next clean large-database

    import because the new `sample_versions(start_date, sample_id)` index from

    `bf5a861` is a write-path tradeoff.