Simplify Checkpoint Version Policy Formatting · Entire

Phase 0 — Gather the diff

Run git diff @{upstream}...HEAD (or git diff main...HEAD / git diff HEAD~1 if there's no upstream) to get the unified diff under review. If there are uncommitted changes, or the range diff is empty, also run git diff HEAD and include the working-tree changes in scope — the review often runs before the commit. If a PR number, branch name, or file path was passed as an argument, review that target instead. Treat this diff as the review scope.

Phase 1 — Review (4 cleanup agents in parallel)

Launch 4 independent review agents via the Agent tool, all in a single message so they run concurrently. Pass each agent the diff and one of the four angles below. Each returns its findings with file, line, a one-line summary, and the concrete cost (what is duplicated, wasted, or harder to maintain).

Reuse

Flag new code that re-implements something the codebase already has — Grep shared/utility modules and files adjacent to the change, and name the existing helper to call instead.

Simplification

Flag unnecessary complexity the diff adds: redundant or derivable state, copy-paste with slight variation, deep nesting, dead code left behind. Name the simpler form that does the same job.

Efficiency

Flag wasted work the diff introduces: redundant computation or repeated I/O, independent operations run sequentially, blocking work added to startup or hot paths. Also flag long-lived objects built from closures or captured environments — they keep the entire enclosing scope alive for the object's lifetime (a memory leak when that scope holds large values); prefer a class/struct that copies only the fields it needs. Name the cheaper alternative.

Altitude

Check that each change is implemented at the right depth, not as a fragile bandaid. Special cases layered on shared infrastructure are a sign the fix isn't deep enough — prefer generalizing the underlying mechanism over adding special cases.

Phase 2 — Apply the fixes

Wait for all four agents to complete, dedup findings that point at the same line or mechanism, and fix each remaining one directly. Skip any finding whose fix would change intended behavior, require changes well outside the reviewed diff, or that you judge to be a false positive — note the skip rather than arguing with it. Finish with a brief summary of what was fixed and what was skipped (or confirm the code was already clean).

2w ago·39m·23 calls

Done. Build passes, focused policy tests green.

Summary

The four cleanup agents (reuse, simplification, efficiency, altitude) reviewed the 32-file checkpoint-policy branch diff. After deduping, one fix applied, five skipped.

Applied — checkpoint_policy.go format helper (simplification): formatCheckpointVersionPolicyValue duplicated the empty-check ((default)) branch from formatCheckpointPolicyValue. Reworked it to express only its one delta — the (unsupported) case — and delegate the rest. Same behavior, less copy-paste, clearer intent.

Skipped, with reasons:

• Efficiency (UnsupportedPolicyMessage "computed twice") — false positive. The session-start and non-start helpers are mutually exclusive event paths; only one runs per invocation.
• persistent.go default reorder — equivalent complexity, no gain.
• hook_registry.go TrimSpace extraction — the two warning messages assemble differently (one joins with \n\n, the other builds via strings.Builder); a shared helper wouldn't simplify either.
• Reuse — git-hook skipUnsupportedCheckpointPolicy vs strategy checkpointPolicyAllowsGitHook — real surface similarity, but they live in different packages with different return semantics (skip-bool vs allow-bool), different writers, and a git-hook-specific read-failure message. Consolidating means a cross-package change with behavior nuances — outside the safe scope of a quality pass.
• Altitude — route all write + hook policy checks through one parametrized gate — I disagree with this on the codebase's own simplicity grounds. The call sites differ because the required behavior differs: write paths must fail, git hooks must skip (never block git), agent hooks must skip on SessionStart but fail otherwise. A single gate with a SkipReason enum and SessionStart special-casing would add a new concept to track, not remove one. The genuinely shared parts (CanSatisfyPolicy, UnsupportedPolicyMessage, readLocalCheckpointPolicy, checkpointPolicyForCheckpointData) are already factored out; the thin per-context orchestration on top is at the right altitude.

No commit made — the working tree change is yours to commit when ready.