Bug: research-doc-cohort-library-false-negative

[drmoisan]

• Work Mode: full-bug

Summary

docs/research/2026-08-10-parallel-bug-flighting-and-surface-blockers.md records the cohort-computation library as absent from both TaskMaster and drm-copilot and instructs the next reader to treat it as new work. The library exists in both repositories. The document's unblock checklist therefore sends a reader to reimplement code that is already present.

Environment

• OS/version: Windows 11 Pro 10.0.26200
• Python version: n/a for the TaskMaster entry point (bash); the upstream authority is Python
• Command/flags used: git grep -in "compute_cohorts|welsh" (the original, defective verification)
• Data source or fixture: docs/research/2026-08-10-parallel-bug-flighting-and-surface-blockers.md at commit 41213a1c

Steps to Reproduce

1. Read §2.1 and §7 item 1 of docs/research/2026-08-10-parallel-bug-flighting-and-surface-blockers.md.
2. Observe the claim that compute_cohorts (Welsh-Powell coloring) does not exist in TaskMaster or in drm-copilot, and that closing the blocker is "new work, not a port."
3. Check .claude/lib/bash/compute-cohorts.sh in TaskMaster.
4. Check scripts/dev_tools/parallel_cohort_computation.py in drm-copilot.

Expected Behavior

The research document's blocker inventory should reflect the actual state of both repositories, so that a reader resuming the plan closes only the blockers that are genuinely open.

Actual Behavior

Both files exist:

• TaskMaster carries a bash entry point at .claude/lib/bash/compute-cohorts.sh (present at commit 2073f717, executable, 4463 bytes). It requires neither Python nor Poetry, so the skill's poetry run python -c "from scripts.dev_tools..." invocation form is not the applicable one here.
• The upstream authority is C:\Users\DanMoisan\repos\drm-copilot\scripts\dev_tools\parallel_cohort_computation.py (commit 663d71ee, issue Bug: quickfiler-keyboard-action-contract-defects #445).

The P5 recomputation-parity concern recorded alongside the blocker is also resolved: the bash port documents itself as reproducing the Python authority's output byte-for-byte, so a parity check compares two independent implementations rather than a module against itself.

Logs / Screenshots

• Attached minimal logs or snippet

• Snippet:

  $ ls -la .claude/lib/bash/compute-cohorts.sh
  -rwxr-xr-x 1 DanMoisan 197121 4463 Aug 11 09:19 .claude/lib/bash/compute-cohorts.sh
  

Impact / Severity

• Blocker
• High
• Medium
• Low

High rather than Blocker: the document is a resumable plan of record explicitly intended to be read instead of re-deriving the analysis. A false "does not exist, build it" entry in its unblock checklist causes duplicated implementation work and misdirects attention away from the one blocker that is genuinely open (the blast-radius truth table).

Source

From: docs/features/potential/2026-08-11-research-doc-cohort-library-false-negative.md