---
model: gpt-5.6-sol
provider: openai
service: opencode
session: ses_0799212ebffe42arY96czXn89F
timestamp: 2026-07-22T00:13:57Z
git_ref: 16f3cd6f
scope: code
substantive: true
raw_file: 20260722T001357Z_16f3cd6f_prompt_io.raw.md
---

## Prompt

Continue the gap-checker and history-backfiller repair plan. Start
with deterministic analysis characterization, then fix canonical
sorting, dedupe-derived columns, positive gap detection, and null
grouping.

During review, the user challenged the replacement null-grouping
algorithm because its initial tests did not assert exact endpoints.
The user explicitly required retaining detailed, human-oriented
algorithm documentation such as the existing ASCII segment map.

## Response summary

Added deterministic analysis regressions and corrected normalization
so sorting and duplicate resolution precede derived-column
calculation. Unified null grouping for NumPy and Polars inputs,
documented its exact inclusive-boundary contract with an adapted
visual map, and verified all small null layouts against an independent
state-machine oracle. Retained sorted smart-dedupe output.

## Files changed

- `piker/tsp/_anal.py` - canonical gap and documented null grouping
- `piker/tsp/_dedupe_smart.py` - sorted duplicate resolution
- `tests/test_tsp_analysis.py` - exact and exhaustive regressions
- `ai/prompt-io/opencode/20260722T001357Z_16f3cd6f_prompt_io.raw.md`
  - unedited response record
- `ai/prompt-io/opencode/20260722T001357Z_16f3cd6f_prompt_io.md`
  - provenance metadata and response summary

## Human edits

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