Overbuild Review Lens

overbuild-review-lens

A deletion-hunting lens. It asks one question the other judges never ask: should this code exist at all? Sibling of architecture-review-lens and the judge-* family — never overlaps with them.

When to use

• A diff adds a helper, a wrapper, a config layer, an abstraction, or a dependency.
• A rewrite, v2, or large refactor landed — the peak over-build context (see minimal-safe-diff-mechanics § The sanctioned-rewrite trap).
• A reviewer asks "is all of this needed?", "could the platform do this?", or "why is this so clever?".

Do NOT use when:

• The concern is whether the code is correct — route to judge-bug-hunter.
• The concern is security — route to judge-security-auditor.
• The concern is naming, single-responsibility, or convention fit of code whose existence is not in question — route to judge-code-quality. That judge asks is this code malformed; this lens asks should it exist.
• The concern is performance — route to performance. Speed is out of scope here.
• The diff is documentation-only or formatting-only.

The scope fence — read this before the first finding

CORRECTNESS, SECURITY AND PERFORMANCE ARE OUT OF SCOPE FOR THIS LENS.
THE MINIMUM RUNNABLE CHECK IS NEVER FLAGGED FOR DELETION.
A SIZE REDUCTION THAT DROPS A GUARD IS A LOSS, NOT A FINDING.

The measured failure mode this fence exists for: a bare "make it simpler" critic was the only arm in a controlled comparison that dropped a safety guard — the three lines it saved were a path-traversal check. Tests, validation, authorization checks, tenant scoping, and error paths that can actually occur are not over-build. If removing something would reduce coverage of a real case, it is not a finding here.

Procedure

1. Establish what the task actually asked for

Read the ticket / prompt, not just the diff. Over-build is measured against the requirement, not against your taste. Anything the diff adds beyond the requirement is a candidate; anything the requirement demands is not, however large.

2. Walk each addition down the solution-size ladder

For every new unit (function, class, module, config key, dependency), find the highest rung that would have carried it — see agent-interaction-and-decision-quality § 8b-ladder:

flatten: is the shape-axis inverse of shrink: — same logic, simpler form, even when that costs a line or two. Without it the lens only ever argues downward and becomes a golfing engine. A nested ternary replaced by an if block is a valid flatten: finding even though the diff grows.

3. Every delete: carries a fence line — no exceptions

Chesterton's Fence, operationalised. Agents are documented as especially fence-blind: complex code reads as an invitation to simplify when the complexity may exist for a reason the reader has no context for. This does not restate minimal-safe-diff's "never delete code that looks dead without proof" — it is the output contract that makes the proof visible.

The fence line has three fields, all required:

Fence: why=<why the code existed — blame, test, issue, or "unknown">
       safe=<the evidence that removal is safe>
       covered=<yes|no|partial — was the removed path under test?>

• why=unknown is a legal value and it is not a pass. It downgrades the finding to a question for the author, never an instruction.
• covered= is the one machine-checkable input to an otherwise archaeological judgement (the Beyoncé rule: if you liked it, you put a test on it). Deleting tested behaviour trips a test and is visible; deleting untested behaviour breaks silently — so covered=no is surfaced as higher risk, not as equivalent.

4. Emit the null when there is nothing to cut

A LENS THAT CANNOT SAY "NOTHING TO CUT" IS A FINDING GENERATOR.

A lean diff must produce the honest null, not an invented finding. This is the load-bearing output, not a fallback: a reviewer who sees findings on every diff stops reading them.

5. Validate before emitting

• Every finding has a file:line and exactly one tag from § 2.
• Every delete: has all three fence fields.
• No finding restates a correctness, security, or performance concern.
• The net-lines summary counts flatten: findings honestly, including the ones that add lines.
• Zero findings → emit the null block, not an empty issues list.

Output format

The verdict block carries these ordered fields:

1. Lens: — fixed value overbuild-review-lens
2. Target: — the diff range or file set reviewed
3. Verdict: — exactly one of lean / trim / overbuilt
4. Findings: — one line per finding: tag, file:line, one sentence; delete: findings carry their Fence: line directly beneath
5. Net: — lines removable if every finding is applied, stated as a signed number so a line-adding flatten: is visible

Lens:    overbuild-review-lens
Target:  <branch / diff range>

Verdict: lean | trim | overbuilt

Findings:
1. stdlib:  src/util/uuid.ts:1     Hand-rolled v4 generator; crypto.randomUUID covers it.
2. delete:  src/config/flags.ts:12 Flag read by nothing since the feature shipped.
   Fence: why=guarded the 2026-03 rollout  safe=zero readers, grep clean  covered=no
3. flatten: src/parser.ts:88       Nested ternary; an if/else reads flat (+2 lines).

Net: -34 lines

The null, when there is nothing to cut — emit verbatim, do not paraphrase:

Lens:    overbuild-review-lens
Target:  <branch / diff range>

Verdict: lean

Findings: none — nothing in this diff exceeds the stated requirement.

Net: 0 lines

Gotcha

• The requirement is the yardstick, not your preference. A large diff that the ticket demanded is not over-built. Say so and emit the null.
• covered=no makes a deletion riskier, not more attractive. The absence of a test is the absence of a tripwire.
• A flatten: finding that saves lines is suspicious. If it is shorter and simpler it is probably a shrink:; flatten: exists for the cases where simplicity costs length.
• Never flag the minimum runnable check. One happy-path test is not over-build; it is the floor.
• Do not count delete: lines that git already removed. The net figure is about the diff as proposed, not the diff's own deletions.

Do NOT

• Do NOT emit a delete: finding without all three fence fields — the output contract rejects it.
• Do NOT invent a finding to avoid an empty report.
• Do NOT review correctness, security, or performance — other surfaces own those, and a size argument against a guard is the canonical failure this lens is fenced against.
• Do NOT report a size number as a score. A size metric is a measurement, never a target.