---
model: openai/gpt-5.6-sol
service: opencode
session: 6409e3bb-1a9a-4ada-b6c4-c554115143e9
timestamp: 2026-07-29T18:54:06Z
git_ref: d359b1cb
scope: code
substantive: true
raw_file: 20260729T185406Z_d359b1cb_prompt_io.raw.md
---

## Prompt

The user reported that QQQ 60-second zeros appeared as a flat line after
reload, clarified that the outstanding concern was the prior `ldshm`
failure, and instructed the agent to implement the more focused fix.

## Response summary

Changed `ldshm` to classify invalid SHM snapshots before downstream
analysis. Cadence is inferred only from observed finite positive steps;
buffers containing non-finite or non-positive timestamps, or lacking a
positive cadence, are skipped rather than partially replacement-written
or reloaded. Added deterministic helper and command-level regressions.

## Files changed

- `piker/storage/cli.py` - inspect cadence and reject invalid SHM snapshots before mutation.
- `tests/test_ldshm.py` - cover QQQ-like zeros, corrupt timestamps, cadence selection, degenerate buffers, and mutation prevention.
- `.claude/skills/run-tests/test-harness-reference.md` - register the deterministic regression target.

## Human edits

None - generated output remains uncommitted.
