Verify Between Waves

A named cadence for multi-file refactors. This codifies what happens in practice on successful large refactors — and what's missing on the ones that go sideways.

Why this exists

Refactors fail when edits compound before any get verified. Classic failure mode: wave 1 edits look fine; wave 2 breaks something subtle in wave 1; by wave 4 the tsc errors are so tangled the repro takes longer than redoing the work.

Session evidence

Applied to the scrapin-aint-easy Tier-A refactor pass (one real session, n=1):

• 7 waves, 24 upgrades, 9 commits
• tsc + tests after every wave before committing
• Regressions caught inside the wave they were introduced:
  • this._initialized rename broke two write sites (caught by tsc immediately after rename wave)
  • now unused after the dead-comparator removal wave (caught on the same tsc pass)
• 9 of 9 commits landed green — no mid-branch rollback ever needed
• Every wave's gate: npx tsc --noEmit && pnpm test — no exceptions

When to use this

Any edit set that:

• Touches >3 files, or
• Touches >3 distinct concerns (security, perf, DX, cleanup, …), or
• Runs longer than 20 minutes of human time, or
• Mixes mechanical cleanup with new-code additions

Skip for single-file fixes, one-line edits, and documentation-only commits.

The cadence

Wave = a logically coherent group of edits that can be reasoned about as one change.

Per wave:
  1. Read the target files (batched, parallel Reads).
  2. Make the edits (batched, parallel Edits). Keep edits narrow and related.
  3. Gate: run typecheck (`tsc --noEmit`) and tests (`pnpm test` or equivalent).
  4. If RED:
     a. Do NOT add more edits.
     b. Fix the regression inside the current wave.
     c. Re-run the gate until GREEN.
     d. If the fix grows the wave beyond "one coherent change", split into two waves
        with a commit boundary between them.
  5. If GREEN:
     a. Commit with a scoped message naming the wave.
     b. Move to the next wave.

After N waves: push.

Wave-sizing heuristics

Signal	Wave size
Mechanical replace_all (e.g., errMsg helper replacing 11 ternaries)	One wave by itself
Related fixes in one file	One wave
Same pattern applied across 2-3 files	One wave
Cross-cutting change (interface extraction, rename of a widely-used symbol)	One wave, then verify, then cleanup wave
New feature + tests	One wave for feature, one for tests

Anti-pattern: stuffing "security fixes + cleanup + new tests + doc update" into one wave.

The gate: what counts as "green"

Minimum:

• Typecheck: no errors
• Tests: all pre-existing tests pass; new tests added in the wave also pass

Better (if available):

• Lint: clean
• Coverage: above the configured threshold
• Smoke: a handful of explicit manual checks where unit tests can't reach (e.g., MCP stdio transport round-trip)

Example: commit messages

wave 1 — security hardening
wave 2 — tools.ts cleanup + schema visibility
wave 3 — pino redact + telemetry race + HNSW init
wave 4 — Puppeteer page pool
wave 5 — safePaginate helper, vector dirty flag

Each message states the wave's coherent theme; body documents what changed and what was left out.

Interaction with other patterns

• Refactor Pipeline (cc-orchestrate.md Template 5): verify-between-waves is the "Verifier" role formalized as a repeating cadence instead of a single final step.
• Checkpointing (skills/checkpointing/SKILL.md): checkpointing saves orchestrator state periodically; verify-between-waves saves code state (commits) periodically. Complementary.
• Context Budget (skills/cc-context-budgeting/SKILL.md): waves are natural /compact boundaries — after each green commit, the surrounding context is a good candidate to summarize.

Rollback recipe (if a wave went bad)

git reset --mixed HEAD~1      # undo the wave commit but keep files
git checkout -- <files>       # drop the bad edits
# or: git stash                # keep them for inspection

Then either redo the wave in smaller steps, or abandon that particular change and move on.

Red flags that you're NOT running this cadence

• You haven't run tsc in 10+ edits.
• You're hoping the tests pass "at the end".
• You have >5 uncommitted files changed.
• You're about to commit 200+ line diff without having run typecheck since the first edit.

Any of these → stop editing, run the gate, commit what's green, re-plan the rest as new waves.