---
model: gpt-5.6-sol
provider: openai
service: opencode
session: unavailable
timestamp: 2026-07-27T20:47:11Z
git_ref: 84a6d47b
scope: code
substantive: true
raw_file: 20260727T204711Z_84a6d47b_prompt_io.raw.md
---

## Prompt

The user identified that `backfiller_deep_fixes` introduced persistent
`.parquet.lock` files, questioned whether Parquet or Arrow already handled
writer coordination, and clarified that piker's `tractor` structured
concurrency design already provides single-writer ownership through the
persistent `datad` feed task. The user then asked to open the backfiller
worktree and resolve the redundant locking.

## Response summary

Removed redundant actor-local and filesystem locking while preserving
atomic crash-safe Parquet replacement. Replaced the synthetic contention
test with regressions for the actual cross-branch failure: writes create
no lock sidecars, and legacy lock artifacts are ignored during indexing.

## Files changed

- `piker/storage/nativedb.py` - rely on `datad` writer ownership
- `tests/test_storage_nativedb.py` - lock-sidecar regressions
- `ai/prompt-io/opencode/20260727T204711Z_84a6d47b_prompt_io.raw.md`
  - unedited response record
- `ai/prompt-io/opencode/20260727T204711Z_84a6d47b_prompt_io.md`
  - provenance metadata and response summary

## Human edits

None - generated changes have not been edited by the human.
