---
model: openai/gpt-5.6-sol
service: opencode
timestamp: 2026-08-05T19:50:01Z
git_ref: f0f3c806
diff_cmd: git diff HEAD~1..HEAD
---

The user reported that a completed NVDA 60s backfill left a large zero
region in live SHM and asked for immediate inspection before restarting the
workspace. The captured buffer contained 42,720 invalid rows at absolute
indexes `3065895..3108614`. The valid rows on both sides had the identical
timestamp `1781271360`, proving the region was an erroneous physical-index
reservation rather than a real temporal gap.

The user then asked the agent to continue fixing the backfill logic.

> `git diff HEAD~1..HEAD -- piker/tsp/_history.py`

Removed wall-clock-based SHM reservation from `tsdb_backfill()`. Reverse
provider frames now extend the visible `ShmArray._first` boundary on every
prepend, beginning exactly at the current first index after inclusive query
endpoints are removed. Added `_prepend_tsdb_history()` to trim storage rows
against the actual earliest provider timestamp and prepend them directly
adjacent only after reverse provider retrieval completes.

This preserves sparse venue history as ordinal samples rather than treating
every elapsed calendar period as a physical SHM row. It also prevents the
old `_first + 1` insertion point from overwriting the earliest published bar.

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

Added a full `tsdb_backfill()` regression modeled on the live NVDA failure.
It uses a real `ShmArray`, NativeDB's field map, two inclusive reverse-provider
frames, and overlapping stored history. Assertions prove the complete
timestamp sequence is contiguous and lossless, contains no non-positive
timestamps, sends complete provider frames to durable storage, and notifies
chart/FSP consumers after the final storage prepend.

Live evidence captured before workspace restart:

```text
rows 1575296 first_index 1568233 last_index 3143528
invalid_count 42720
left boundary
[(3065893, 1781271300, 204.03, 204.82)
 (3065894, 1781271360, 204.81, 204.72)
 (3065895,          0,   0.  ,   0.  )]
right boundary
[(3108614,          0,   0.  ,   0.  )
 (3108615, 1781271360, 204.81, 205.44)
 (3108616, 1781271420, 205.46, 205.48)]
```

Verification output:

```text
........................................................................ [ 68%]
.................................                                        [100%]
105 passed in 4.80s
```

Adversarial review caught stale `_first` semantics and an off-by-one
insertion point in the initial patch. The first live restart then exposed an
undefined `time_key` local at the new `tsdb_backfill()` call site, which
crashed `datad.ib` and propagated to the chart as `RemoteActorError`. The
helper now derives the source timestamp field from its field map, and the
test enters the full enclosing lifecycle so the original `NameError` can not
recur unnoticed. A final review also drove explicit publication after stored
history is prepended and deterministic final-stage synchronization. Final
review found no remaining issues; another live restart remains pending.