---
model: openai/gpt-5.6-sol
service: opencode
timestamp: 2026-07-29T18:54:06Z
git_ref: d359b1cb
diff_cmd: git diff HEAD~1..HEAD
---

The user clarified that the QQQ 60-second chart now displayed a flat
forward-filled segment, then asked whether the previously reported
`piker store ldshm` failure had been fixed. After being told it had not,
the user instructed: "ok but i read above you have a more focussed fix
todo now? so have at it!"

The implementation focused on the exact failure boundary. It does not
filter invalid rows into a partial replacement and does not mutate live
SHM. Instead, `ldshm` inspects one captured Polars snapshot, infers its
cadence from observed finite positive timestamp steps, and skips the
entire buffer before analysis, persistence, or reload when any timestamp
is non-finite or non-positive.

> `git diff HEAD~1..HEAD -- piker/storage/cli.py`

Generated `_shm_period_and_invalid_count()` and integrated its result in
`ldshm`. The helper selects the most frequent observed positive step,
using the smallest observed step as the deterministic tie-break. Short
or cadence-degenerate buffers are skipped. Invalid snapshots are logged
and cannot reach deduplication, NativeDB replacement, or SHM reload.

> `git diff HEAD~1..HEAD -- tests/test_ldshm.py`

Generated deterministic regressions for the QQQ-shaped interior zero
run, observed-step cadence selection, all invalid timestamp classes,
short and degenerate buffers, and command-level prevention of dedupe,
storage writes, and reload. The command-level test uses an immutable
Polars snapshot and failing spies, without live SHM mutation or timing.

> `git diff HEAD~1..HEAD -- .claude/skills/run-tests/test-harness-reference.md`

Added the deterministic `ldshm` regression target and its change-to-test
mapping to the repository test harness reference.

Verification output:

```text
..........................................................               [100%]
58 passed in 0.70s
```

`git diff --check` passed. Ruff was unavailable in the worktree's
existing environment. Three adversarial review passes found and drove
fixes for partial-replacement data loss, invented median timeframes,
mixed SHM observations, and pre-guard null-analysis failures. The final
review reported no remaining findings.

The patch intentionally does not claim that `ldshm` is safe to run as a
general concurrent repair writer. It handles invalid live snapshots by
refusing mutation rather than weakening NativeDB validation.
