# Sprint 256 Execution Tracker - 2026-02-26

## Scope
- `sprint256_plan.md`

## Implemented

Scorer enhancement:
- `tools/mcp/score_native_tasks_profile_coverage.py`
  - Added optional `--top-gaps <raw_gap_backlog.json>`.
  - Computes:
    - `top_gap_signal_count`
    - `top_gap_signal_hits`
    - `top_gap_signal_weight_total`
    - `top_gap_score`

Pipeline integration in `tools/mcp/run_sprint_taskitem_pipeline.sh`:
- Added:
  - `WSTONE_NATIVE_RAW_TOP_GAP_WEIGHTED_SELECT`
  - `WSTONE_NATIVE_RAW_TOP_GAP_BACKLOG_FILE`
- Raw search summary now emits:
  - `baseline_top_gap_score`
  - `best_top_gap_score`
  - `top_gap_weighted_select`
  - `top_gap_backlog_file`
- Candidate selection policy:
  - first minimize `failing_profile_count`
  - if tied and weighted mode enabled, maximize `top_gap_score`
  - then maximize `task_count`

## Validation Artifacts

Raw search A/B (weighted selector off/on):
- OFF:
  - `logs/taskitem_runs/01a_fallback_intake_spec_20260226_162422/00_summary.json`
- ON:
  - `logs/taskitem_runs/01a_fallback_intake_spec_20260226_162423/00_summary.json`

Observed result on hard sample:
- `selected_variant` unchanged (`0`)
- `best_failing_profile_count` unchanged (`1`)
- `best_top_gap_score` remained `0` for this sample

Scorer sanity check on hardened tasks:
- `python3 tools/mcp/score_native_tasks_profile_coverage.py ... --top-gaps ...`
- output: `/tmp/sprint256_score_check.json`
- observed:
  - `top_gap_signal_hits=18/20`
  - `top_gap_score=86`

## Explicit Completion Signal

- Sprint 256: `DONE` (implemented + measured; no intrinsic uplift yet on this hard sample)