Biome anti-slop

Vendor the bundled rules into the current repository and integrate them with its existing Biome setup. Preserve unrelated work and adapt to the repository's package manager and configuration.

Install

1. Inspect the repository before changing it:

   • Read applicable agent instructions and check git status.
   • Detect the package manager from packageManager and lockfiles.
   • Find biome.json or biome.jsonc files and existing anti-slop rules.
   • If multiple independent Biome roots exist, ask which one to configure.

2. Require @biomejs/biome version >=2.5.9 <3. Preserve an existing dependency in that range. If Biome is absent from a package manifest, install the latest compatible 2.x release using @biomejs/biome@^2.5.9 as a development dependency with the repository's package manager. If the repository uses a version outside that range, stop and ask before changing it.

3. From the target repository, copy the bundled rules:

   node <skill-directory>/scripts/install.js
   

   The default destination is tools/biome/anti-slop. Pass another relative destination as the first argument when the repository has an established tooling layout. The installer refuses to replace an existing destination; use --force only after reviewing the existing files and the replacement diff.

4. Register the installed rules. Do not type the rule names from memory or from this file. The installer prints two lists, read from the // scope: line each rule declares, so they cannot go stale as rules are added, merged, or removed:

   • the global list goes in the top-level plugins array;
   • the tests list goes in a plugins array on an overrides entry matching **/*.test.ts and **/*.test.tsx, because those patterns are legitimate in product code and only wrong in a test.

   Add them without removing existing plugins.

   Preserve every existing configuration field. Also enable these native Biome rules at error severity, merging them into their existing groups:

   {
     "linter": {
       "rules": {
         "complexity": {
           "noBannedTypes": "error",
           "noUselessTypeConstraint": "error"
         },
         "nursery": {
           "noMisleadingReturnType": "error",
           "noUnsafeTypeAssertion": "error",
           "useReduceTypeParameter": "error"
         },
         "style": {
           "noNonNullAssertion": "error",
           "useAsConstAssertion": "error"
         },
         "suspicious": {
           "noExplicitAny": "error",
           "noFocusedTests": "error",
           "noSkippedTests": "warn"
         }
       }
     }
   }
   

   noFocusedTests is an error because a stray it.only silently disables the rest of its file; noSkippedTests is a warning because a skip has honest uses and only needs a comment naming what unblocks it. Confirm every rule name and its current group with the installed Biome binary before editing configuration. The groups above are correct for Biome 2.5.9; if biome explain reports that a later compatible 2.x release promoted a nursery rule, use its reported stable group. Stop if any rule is unavailable rather than writing an invalid configuration.

   If one of these rules already uses object configuration, preserve its options and change only its level to error. If linter.enabled is explicitly false, stop and ask before enabling it. Add the vendored anti-slop directory to files.includes as a negated pattern so routine checks do not reformat vendored rules. Also add negated patterns for project-local agent tooling directories that actually exist, such as .agents or .codex; do not ignore all dot-directories. If no Biome configuration exists, create a minimal one with the local schema, the plugin list, and those file exclusions.

5. Keep each rule's declared severity. The set runs at two levels and the difference is a promise: error is for a pattern with no honest counter-example, warn for a judgement a pattern cannot make - an options-object parameter is a readability call, whether a Map in a store is always replaced whole is a fact about the component, and whether a module has an injectable seam is a fact about the code under test. A warning is a prompt to think, never a demand to rewrite.

   A judgement the pattern cannot make at all is a different thing, and does not belong in the set: a rule that fires mostly on correct code trains readers to skim every warning beside it. Neither does a rule Biome already ships - noUnsafeTypeAssertion and noExplicitAny own their patterns here, and a second diagnostic on the same line adds nothing to read.

6. Every rule ships a fixture beside it under fixtures/, marking each line the rule must reject with a trailing // flag and surrounding it with correct code the rule must leave alone. A GritQL pattern that matches nothing is green and enforces nothing, so a rule without a fixture proving both halves is not a rule. If the target repository adds one, it adds a fixture too.

7. Run the repository's existing lint or check command. If none exists, run Biome directly. Report findings in owned source and fix them only when the user requested migration or cleanup. Do not suppress diagnostics, weaken their severity, or launder types to make the check pass.

8. Review the final diff and report the copied path, dependency change, configuration change, checks run, and any remaining findings.