fix(skill): deft-swarm Phase 6 -- require read-back verification after rebase conflict resolution

[MScottAdams]

Summary

During the v0.16.0 swarm merge cascade, a CHANGELOG.md conflict resolution using a PowerShell -replace regex produced a corrupted file (two bullet entries collapsed onto one line with a literal backtick-n separator instead of a real newline). The corruption was not caught before git add and was only surfaced by Greptile's re-review.

Root Cause

Two gaps in the deft-swarm Phase 6 rebase conflict resolution flow:

1. No read-back step after conflict resolution: The skill instructs the monitor to resolve conflicts and run git add, but does not require re-reading the resolved file to verify structural integrity before staging. The mandatory pre-commit file review rule (t1.11.4) applies to agent commits but is not explicitly called out in the monitor's conflict resolution path.

2. Shell operation trust without verification: A -replace regex in PowerShell's substitution context behaves differently from a double-quoted string (backtick-n is not expanded). edit_files is safer for structured content edits -- the line-by-line output confirms the result immediately.

Proposed Fix

Add a ! rule to skills/deft-swarm/SKILL.md Phase 6 Step 1 rebase cascade:

• After resolving any conflict and before running git add, re-read the resolved file and visually verify structural integrity (no conflict markers, no collapsed lines, no encoding artifacts)
• Prefer edit_files over shell regex for CHANGELOG.md and SPECIFICATION.md conflict resolution
• Mirrors the mandatory pre-commit file review from t1.11.4, targeted at rebase conflict resolution

Context

• Discovered during: v0.16.0 swarm cascade (2026-04-10)
• PR affected: fix(workflow): semantic accuracy check in mandatory pre-commit file review (#274) #285 (required a second force-push + Greptile re-review cycle)
• Related: t1.11.4 (mandatory pre-commit file review), t1.15.1 (semantic accuracy check)

[MScottAdams]

Roadmap Refresh Analysis (2026-04-10)

Category: Bug fix / skill enforcement gap

Summary: During the v0.16.0 swarm merge cascade, a PowerShell -replace regex produced a corrupted CHANGELOG.md with no read-back step to catch it. The corruption was only surfaced by Greptile's re-review, burning an extra re-review cycle.

Relationship to existing issues:

• t1.11.4 (mandatory pre-commit file review) -- same principle, not wired into the rebase conflict resolution path in deft-swarm Phase 6
• t1.15.1 (semantic accuracy check) -- companion rule also absent from rebase path
• chore(swarm): monitor crash during multi-PR merge — add checkpoint/recovery resilience #263 (swarm crash recovery, completed v0.16.0) -- same Phase 6 area

Scope: Small -- adds ! rule to deft-swarm Phase 6 Step 1 rebase conflict resolution: re-read and verify resolved file before git add; prefer edit_files over shell regex for structured files.

Recommendation: Phase 1 -- process enforcement gap that directly caused a PR corruption event requiring an extra Greptile re-review cycle. Clear quality blocker.