verify-no-regressions

name	verify-no-regressions
argument-hint	[count] [base-branch]
description	Verify no behavioral regressions after implementation. Spawns parallel sonnet subagents for semantic diff review + test execution. Use when: user says "verify no regressions", "check for regressions", "make sure nothing broke".

Verify No Regressions

Usage: /verify-no-regressions [count] [base-branch] (defaults: 1 main)

Work state

• Working tree: !git status --short 2>/dev/null || echo "(not a git repo)"
• Commits ahead of base: !set -- $ARGUMENTS; git log --oneline "${2:-main}"...HEAD 2>/dev/null || echo "(none or invalid base)"
• Committed diff: !set -- $ARGUMENTS; git diff --stat "${2:-main}"...HEAD 2>/dev/null
• Staged diff: !git diff --cached --stat 2>/dev/null
• Unstaged diff: !git diff --stat 2>/dev/null
• Test scripts: !cat package.json 2>/dev/null | jq -r '.scripts | to_entries[] | select(.key | test("test";"i")) | "\(.key): \(.value)"' 2>/dev/null || echo "(no package.json)"

Instructions

Read the work state above to determine what happened:

• Committed: commits ahead of base, clean working tree → review with git diff base...HEAD
• Staged: files in staging → review with git diff --cached
• Unstaged/untracked: modified or new files → review working tree files directly
• Mixed: combination of the above → review all layers

If nothing changed anywhere, report that and stop.

Spawn sonnet subagents in a single message. Tell each agent which diff commands to use based on the work state.

1. Semantic reviewers -- split changed files across $0 agent(s) (default: 1). Each agent:

   • Reads the diff (using the appropriate command for the work state) and current file contents
   • Classifies each change as INTENTIONAL, RISKY (could break callers), or REGRESSION
   • Reports verdict: PASS / NEEDS_REVIEW / FAIL

2. Test runner (skip if no test infrastructure) -- one additional agent that runs the test suite and reports PASS / FAIL.

After all agents complete, synthesize a single report with overall verdict.