Setup

Purpose

Thin check-centric setup per the uniform setup contract (docs/PLUGIN-PHILOSOPHY.md "Setup is explicit and repeatable" in the marketplace repository): check inspects and reports, apply resolves. This plugin owns no consumer-project configuration. Rules come from the repository's own Biome config, and the only tunable is the native userConfig toggle, so apply is guidance-and-verify, with exactly one write path: the explicitly invoked apply install-biome dependency install described below.

Action routing: no argument or check runs the check; apply runs the check first, then remediation; apply install-biome additionally authorizes the consumer-repo dependency install described below. All are non-interactive. Never prompt when the action is given.

check (read-only)

The hook script (${CLAUDE_PLUGIN_ROOT}/hooks/biome-format.sh) is the single source of truth for what it requires and how it resolves things.

Read it first. Probe what it actually does, don't recite this file. Then run each probe via Bash and report a PASS/FAIL/INFO table with one remediation line per FAIL. Do not modify anything.

When the plugin's toggle is disabled, every prerequisite absence downgrades from FAIL to INFO. The hook exits through its enabled-gate before probing anything, so a deliberately disabled plugin is not broken. Report the probes informationally and note that re-enabling restores the FAIL semantics.

1. Bash version. Check against the hook's documented floor (README Requirements), noting any features the hook degrades without (for example telemetry's EPOCHREALTIME, Bash 5.0+).
2. jq. command -v jq. FAIL if absent: the hook then skips with a visible once-per-session notice instead of formatting.
3. Biome binary. Resolve it exactly the way the hook's resolution code does: its repo-local install walk (the node_modules/.bin path it tests, walking up from the edited file toward the repo root) and then PATH. Test only what the hook tests. A binary the hook would not accept must not PASS here. FAIL when nothing the hook would resolve is present while a Biome config governs the repo; the hook then emits a visible once-per-session skip notice instead of formatting.
4. Consumer Biome config. Mirror the hook's opt-in walk: it records the topmost governing config found walking from the edited file's directory up to the repo root, and deliberately accepts only the config names the hook treats as the opt-in. Read the hook: the hidden dotted variants are intentionally excluded. Report the governing config the walk discovers, or INFO that none exists. Absence is the opt-out by design, so the plugin is inert (INFO, not FAIL), matching the README's "ships no rules of its own" stance.
5. Hook toggle. Report the effective biome_format_enabled value: ${user_config.biome_format_enabled} (unexpanded or empty means default true).
6. Hook registration. INFO: confirm the plugin is enabled for this project (/plugin → Installed) rather than parsing settings files.

apply (idempotent)

Run check, then for each FAIL offer the resolution. Never install anything without the consumer's explicit go-ahead in the invocation. apply install-biome adds @biomejs/biome as a dev dependency in the consumer repository using the repository's own package manager, resolved in order: lockfile (pnpm-lock.yaml → pnpm add -D, yarn.lock → yarn add -D, bun.lock/bun.lockb → bun add -d, package-lock.json → npm install --save-dev), then the package.json "packageManager" field when no lockfile exists, then npm only when neither signal is present. With no package.json, an ambiguous multi-lockfile state, or a lockfile that contradicts packageManager, stop with manager-specific guidance instead of guessing. Never introduce a competing lockfile. The change is stated before running. For a Yarn repository, don't infer the linker. Ask the repo's own Yarn: run yarn config get nodeLinker in the repo. pnp (Berry's default when unset) → skip the install and give guidance, because Plug'n'Play generates a loader file, not the node_modules/.bin shim the hook resolves; install @biomejs/biome on PATH or switch the linker. node-modules/pnpm, or Yarn Classic (which has no such setting and always materializes node_modules) → install. The verify-after-remediation rule below is the backstop when an install still yields no usable shim. After ANY remediation, re-run the relevant check probe and report its actual result. Never claim resolved on the install command's exit code alone. For everything else apply only points:

• missing jq / Bash: platform install instructions from the README Requirements section; this skill never installs system packages.
• toggle off: reconfigure through Claude Code's native flow, per the marketplace's plugin-reconfiguration convention (https://github.com/melodic-software/claude-code-plugins/blob/main/docs/conventions/plugin-reconfiguration/README.md, which owns the verified-version record): interactive /plugin configure biome-format@<marketplace> any time, or headless claude plugin install biome-format@<marketplace> -s <scope> --config biome_format_enabled=true (repeatable per key) — against an already-installed plugin it prints already installed and still writes the value. Do not uninstall to reconfigure: that drops this plugin's entire stored pluginConfigs entry, resetting every option in the README's Options reference to its manifest default. -s defaults to user; pass the scope claude plugin list reports for this plugin, and run from that project's directory for a project/local scope, or the write lands at a scope that does not load. This skill never writes user settings or pluginConfigs. Afterwards rerun check in a fresh session — the rendered ${user_config.*} is injected at skill load and each hook receives its CLAUDE_PLUGIN_OPTION_* from an environment fixed at session start, so a same-session check still reports the OLD value; report the observed effective value, never an unobserved change.
• no Biome config: offer to create a minimal biome.json in the repository root only when explicitly asked. The plugin imposes no rules of its own.

Re-running apply after everything passes changes nothing and reports "already configured".

What this skill does NOT do

• Run the formatter. Editing any supported file exercises the hook end-to-end.
• Write the plugin cache, Claude Code user settings, or pluginConfigs.
• Download or execute tools during check; network use happens only in an explicitly requested apply install-biome inside the consumer repository.