adversarial-zod

Adversarial Zod Gate

A currency and correctness gate for Zod schema code in TypeScript apps — a pass/fail gate: a single blind reviewer subagent judges the work against this gate's rules with an adversarial mandate, and the work passes only when every rule is PASS or N/A. This skill renders verdicts; it never fixes the work.

Rules are pinned to zod 4.4.x (package root since [email protected], July 2025) and, for the start- category, the TanStack Start v1 RC (.validator() current, .inputValidator() deprecated).

When to Apply

• A diff or feature that defines or edits Zod schemas is about to merge and needs an objective PASS/FAIL on Zod 4 currency, not advisory feedback.
• An agent (Claude, Codex) authored schema code and you want an independent check that it is not reproducing Zod 3 training-data patterns — deprecated method forms, removed params, or the z.interface() hallucination.
• A Zod 3 → 4 migration claims completion and needs the silent semantic breaks audited (.default() short-circuiting, exhaustive enum-keyed records, z.coerce.boolean() on string flags).
• A TanStack Start app validates server-function input or search params with Zod and should be on the adapter-free Standard Schema patterns.

Do not apply to Zod 3 codebases (the reviewer prompt's precondition aborts with "GATE NOT APPLICABLE"), or when the user wants explanations and refactors rather than a verdict — that is the curated zod distillation skill's job. The two start- rules go N/A outside TanStack apps; the rest of the gate works in any TypeScript project using Zod 4.

Review Protocol

Follow these steps exactly — the gate's value is that every review runs the same way.

1. Identify the target. Pin down exactly what is under review (a diff, a set of files, a PR) and note the ref/paths so the review runs against an unambiguous, fixed target. Always include package.json in the target paths — the Zod-4 precondition and the pkg-, compose-native-json-schema, and start- adapter rules are decided by its dependency pins even when the diff does not touch it.
2. Load the rules. Read references/_sections.md and every rule file in references/ (all sem-*.md, gone-*.md, err-*.md, dep-*.md, compose-*.md, start-*.md, pkg-*.md files).
3. Compose the reviewer prompt. Fill references/reviewer-prompt.md with the rules and the target. The composed prompt must be fully self-contained — a reviewer sees no conversation history, so nothing may refer to context outside the prompt.
4. Dispatch one blind reviewer. Launch a single Task subagent whose entire input is the composed prompt — no conversation context, no commentary alongside it.
5. Render fail-closed. The reviewer's structured output is the verdict — there is no merge step. Overall verdict is PASS only when every rule is PASS or N/A; any single FAIL fails the gate. Never average, weigh severity, or waive a rule — a "minor" FAIL is a FAIL. If the reviewer returns "GATE NOT APPLICABLE" (Zod 3 or no Zod), stop and report that instead of a verdict.
6. Render the verdict. Fill assets/templates/verdict.md. On FAIL, aggregate the reviewer's "missing for PASS" suggestions into the fix list, each with its location, ordered by category importance. Every rule whose final result is FAIL must appear in the fix list with a change concrete enough to apply as written — if the reviewer's suggestion only restates the violation, derive the fix from the rule's Correct example before rendering.

If the same rule flips verdicts across re-reviews of an unchanged target, or a human reads the evidence and overrides the verdict, that is a decidability bug in the rule — record it in gotchas.md and sharpen the rule; do not override the gate.

Verdict Format

The reviewer returns, per rule: PASS | FAIL | N/A, evidence (file:line or a quote — required for PASS as well as FAIL), and for every FAIL, the fix that flips the rule to PASS once applied — the named change plus its location, never a restatement of the violation. The final report follows assets/templates/verdict.md.

Rule Categories

#	Category	Prefix	Covers
1	Silent Semantic Breaks	sem-	.prefault() for parsed defaults, z.partialRecord() for sparse enum keys, z.stringbool() for string flags
2	Removed APIs	gone-	.ip()/.cidr(), single-arg z.record(), error params trio, .errors getter, function factory, z.interface() hallucination
3	Error Customization & Formatting	err-	Unified error param over message, top-level z.treeifyError/z.flattenError/z.prettifyError
4	Deprecated Method Forms	dep-	Top-level string formats, z.strictObject/z.looseObject, .extend over .merge, z.enum over z.nativeEnum, z.int(), no z.promise()
5	Composition, Recursion & Codecs	compose-	Getter recursion, z.codec() for bidirectional wire transforms, native z.toJSONSchema()
6	TanStack Start Integration	start-	Bare schema to .validator(), adapter-free validateSearch
7	Packaging & Imports	pkg-	Root "zod" import path, zod/mini reserved for hard bundle constraints

Related Skills

• zod (curated) — the teaching-style distillation for Zod usage; use it when the goal is explanation or refactoring rather than a verdict.
• adversarial-tanstack — the framework-level gate for TanStack Start apps; run both on a Start diff for full coverage (its serverfn-validate-input checks that a validator exists; this gate's start- rules check the validator uses current Zod 4 patterns).

Reference Files

File	Description
references/reviewer-prompt.md	Self-contained prompt template for the blind reviewer
assets/templates/verdict.md	Verdict report template
references/_sections.md	Category definitions and ordering
metadata.json	Version and source references