diff --git a/bin/verify-workspace-config.mjs b/bin/verify-workspace-config.mjs
index a611c2f..7df4854 100755
--- a/bin/verify-workspace-config.mjs
+++ b/bin/verify-workspace-config.mjs
@@ -169,11 +169,24 @@ function localManifest(root) {
       }
     : undefined;
 
+  // package.json (parsed) so the biome-linter rule can read the @biomejs/biome
+  // dep. null = not a node repo (Python/Rust/etc) → the rule is N/A there.
+  let packageJson = null;
+  try {
+    const pkgPath = join(root, 'package.json');
+    if (tracked ? tracked.has('package.json') : existsSync(pkgPath)) {
+      packageJson = JSON.parse(readFileSync(pkgPath, 'utf8'));
+    }
+  } catch {
+    packageJson = null;
+  }
+
   return {
     hasFile: (p) => (tracked ? tracked.has(p) : existsSync(join(root, p))),
     gitignore,
     ...(isIgnored ? { isIgnored } : {}),
     workflowRunners,
+    packageJson,
   };
 }
 
@@ -220,6 +233,8 @@ async function remoteManifest(repo, ref) {
     '.beads/issues.jsonl',
     '.beads/beads.db',
     '.automaker/settings.json',
+    'biome.json',
+    'biome.jsonc',
   ];
   const present = new Set();
   await Promise.all(
@@ -269,7 +284,20 @@ async function remoteManifest(repo, ref) {
     /* no .github/workflows dir */
   }
 
-  return { hasFile: (p) => present.has(p), gitignore, workflowRunners };
+  // Fetch + parse package.json (for the biome-linter rule). null = not a node repo.
+  let packageJson = null;
+  try {
+    const { stdout } = await execFileAsync(
+      'gh',
+      ['api', `repos/${owner}/${name}/contents/package.json?ref=${resolvedRef}`, '--jq', '.content'],
+      { encoding: 'utf8' }
+    );
+    packageJson = JSON.parse(Buffer.from(stdout.trim(), 'base64').toString('utf8'));
+  } catch {
+    packageJson = null;
+  }
+
+  return { hasFile: (p) => present.has(p), gitignore, workflowRunners, packageJson };
 }
 
 async function defaultBranch(owner, name) {
diff --git a/docs/reference/workspace-config-standard.md b/docs/reference/workspace-config-standard.md
index f0c8f02..561210a 100644
--- a/docs/reference/workspace-config-standard.md
+++ b/docs/reference/workspace-config-standard.md
@@ -22,6 +22,7 @@ Enforced by `verify-workspace-config` (this package).
 | `automaker-transient-gitignored` | warn     | `.automaker/features/`, `checkpoints/`, `trajectory/` gitignored; `settings.json` + `context/` stay committed                                           |
 | `workflows-use-owned-runners`    | error    | every `runs-on:` is an org-owned runner (`namespace-profile-protolabs-linux`), never GitHub-hosted (`ubuntu-*`, `windows-*`, `macos-*`)                 |
 | `workflow-security-lint`         | warn     | `.github/workflows/workflow-security-lint.yml` exists — zizmor + actionlint run in CI (CWE-94 script-injection, unpinned actions, token over-privilege) |
+| `biome-linter`                   | warn     | JS/TS repos (those with a `package.json`) lint with **biome** at the fleet-pinned version (`FLEET_BIOME_VERSION`); non-node repos are N/A                |
 
 **Errors gate CI. Warnings are advisory.**
 
@@ -81,6 +82,29 @@ jobs:
 `warn` for now so the fleet can roll out without breaking CI on day one;
 tighten to `error` once every managed repo carries it.
 
+### Why JS/TS repos track one biome version
+
+protoLabs standardizes JS/TS linting on [biome](https://biomejs.dev) — one fast
+single-binary linter, no ESLint plugin sprawl. The fleet tracks **one** biome
+version together so a lint rule means the same thing in every repo and upgrades
+land in lockstep instead of scattering into per-repo drift.
+
+The pinned version lives in **one place** — `FLEET_BIOME_VERSION` in
+`release-tools` (`lib/workspace-config.mjs`). Bump it there and
+`verify-workspace-config` flags every node repo that hasn't followed, with the
+gap spelled out in the detail line (no `@biomejs/biome` dep → still on ESLint;
+biome declared but no `biome.json`; or a version different from the fleet pin).
+Adopt or catch up with:
+
+```bash
+npm i -D @biomejs/biome@<FLEET_BIOME_VERSION>   # the version from the table above
+npm pkg set scripts.lint="biome lint ."          # add a biome.json, drop ESLint
+```
+
+The rule is **N/A for non-node repos** (Python, Rust — no `package.json`), so it
+never fires there. `warn` for now so adoption rolls out without breaking CI;
+tighten to `error` once every node repo is on biome.
+
 ### Why `.automaker/settings.json` is committed per-repo
 
 The per-repo settings file pins the agent baseline — gateway model tiers
diff --git a/lib/workspace-config.mjs b/lib/workspace-config.mjs
index fa70860..e1aaca6 100644
--- a/lib/workspace-config.mjs
+++ b/lib/workspace-config.mjs
@@ -118,6 +118,29 @@ jobs:
 /**
  * The standard. Ordered; errors gate CI, warns are advisory.
  */
+/**
+ * The biome version the fleet tracks together. Single source of truth: bump it
+ * here and `verify-workspace-config` flags every JS/TS repo that hasn't followed,
+ * so the fleet upgrades biome in lockstep instead of drifting per-repo.
+ */
+export const FLEET_BIOME_VERSION = '2.4.16';
+
+/** Strip a semver range prefix (^ ~ >= <= = and whitespace) → the bare version. */
+export function cleanVersion(spec) {
+  return String(spec ?? '')
+    .trim()
+    .replace(/^[\^~>=<\s]+/, '');
+}
+
+/**
+ * The declared @biomejs/biome version spec from a parsed package.json, or null
+ * if the repo doesn't depend on biome. Checks devDependencies then dependencies.
+ */
+export function biomeVersion(pkg) {
+  if (!pkg || typeof pkg !== 'object') return null;
+  return pkg.devDependencies?.['@biomejs/biome'] ?? pkg.dependencies?.['@biomejs/biome'] ?? null;
+}
+
 export const WORKSPACE_STANDARD = /** @type {Rule[]} */ ([
   {
     id: 'beads-issues-jsonl',
@@ -196,6 +219,33 @@ export const WORKSPACE_STANDARD = /** @type {Rule[]} */ ([
     ok: (m) => m.hasFile(WORKFLOW_SECURITY_LINT_PATH),
     fix: `Add ${WORKFLOW_SECURITY_LINT_PATH} (run \`init-workspace-config\`, or call the reusable workflow: \`uses: protoLabsAI/release-tools/.github/workflows/workflow-security-lint.yml@main\`)`,
   },
+  {
+    id: 'biome-linter',
+    description: `JS/TS repos lint with biome ${FLEET_BIOME_VERSION} — the fleet tracks one biome version together (no ESLint, no per-repo version drift)`,
+    // warn (not error) so adoption rolls out across the fleet without breaking CI
+    // on day one — same posture as workflow-security-lint. Tighten to error once
+    // every node repo is on biome. N/A for non-node repos (Python/Rust have no
+    // package.json) → ok=true so they don't show as violations.
+    severity: 'warn',
+    ok: (m) => {
+      if (!m.packageJson) return true;
+      const v = biomeVersion(m.packageJson);
+      if (!v) return false;
+      if (!m.hasFile('biome.json') && !m.hasFile('biome.jsonc')) return false;
+      return cleanVersion(v) === cleanVersion(FLEET_BIOME_VERSION);
+    },
+    fix: `Track the fleet biome: \`npm i -D @biomejs/biome@${FLEET_BIOME_VERSION}\`, add a biome.json, set \`"lint": "biome lint ."\` (drop ESLint). Fleet version is pinned in release-tools FLEET_BIOME_VERSION.`,
+    detail: (m) => {
+      if (!m.packageJson) return [];
+      const v = biomeVersion(m.packageJson);
+      if (!v) return ['no @biomejs/biome dependency (still on ESLint, or unlinted?)'];
+      if (!m.hasFile('biome.json') && !m.hasFile('biome.jsonc'))
+        return [`@biomejs/biome ${v} declared but no biome.json / biome.jsonc`];
+      if (cleanVersion(v) !== cleanVersion(FLEET_BIOME_VERSION))
+        return [`biome ${v} — fleet tracks ${FLEET_BIOME_VERSION}`];
+      return [];
+    },
+  },
 ]);
 
 /**
diff --git a/test/workspace-config.test.mjs b/test/workspace-config.test.mjs
index 85ecec7..94f1936 100644
--- a/test/workspace-config.test.mjs
+++ b/test/workspace-config.test.mjs
@@ -12,6 +12,9 @@ import {
   SCAFFOLD_FILES,
   REQUIRED_GITIGNORE,
   WORKFLOW_SECURITY_LINT_PATH,
+  FLEET_BIOME_VERSION,
+  cleanVersion,
+  biomeVersion,
 } from '../lib/workspace-config.mjs';
 
 /** Build a manifest from a list of present files + gitignore text. */
@@ -364,3 +367,82 @@ test('planScaffold leaves selective .automaker/features/ alone (no false removal
   assert.deepEqual(plan.gitignoreRemovals, []);
   assert.deepEqual(plan.gitignoreAdditions, []);
 });
+
+// ── biome-linter (fleet biome version tracking) ──────────────────────────────
+
+/** Build a manifest for a node repo with a given biome dep + biome.json presence. */
+function nodeManifest({ biomeDep, hasBiomeJson = true, dev = true } = {}) {
+  const files = new Set(hasBiomeJson ? ['biome.json'] : []);
+  const deps = biomeDep ? { '@biomejs/biome': biomeDep } : {};
+  return {
+    hasFile: (p) => files.has(p),
+    gitignore: '',
+    packageJson: { [dev ? 'devDependencies' : 'dependencies']: deps },
+  };
+}
+
+const biomeViolation = (m) =>
+  evaluateStandard(m).violations.find((v) => v.id === 'biome-linter');
+
+test('cleanVersion strips semver range prefixes', () => {
+  assert.equal(cleanVersion('2.4.16'), '2.4.16');
+  assert.equal(cleanVersion('^2.4.16'), '2.4.16');
+  assert.equal(cleanVersion('~2.4.16'), '2.4.16');
+  assert.equal(cleanVersion('>=2.4.16'), '2.4.16');
+  assert.equal(cleanVersion(' 2.4.16 '), '2.4.16');
+  assert.equal(cleanVersion(undefined), '');
+});
+
+test('biomeVersion reads devDependencies then dependencies, null when absent', () => {
+  assert.equal(biomeVersion({ devDependencies: { '@biomejs/biome': '2.4.16' } }), '2.4.16');
+  assert.equal(biomeVersion({ dependencies: { '@biomejs/biome': '^2.0.0' } }), '^2.0.0');
+  assert.equal(biomeVersion({ devDependencies: { eslint: '^9' } }), null);
+  assert.equal(biomeVersion(null), null);
+});
+
+test('biome-linter is N/A for non-node repos (no packageJson)', () => {
+  // Python/Rust repos have no package.json → rule passes, no violation.
+  const m = { hasFile: () => false, gitignore: '' };
+  assert.equal(biomeViolation(m), undefined);
+  assert.ok(evaluateStandard(m).passed.includes('biome-linter'));
+});
+
+test('biome-linter passes when a node repo is on the fleet biome version', () => {
+  const m = nodeManifest({ biomeDep: FLEET_BIOME_VERSION });
+  assert.equal(biomeViolation(m), undefined);
+  // a caret range on the same version still matches (cleanVersion strips ^)
+  assert.equal(biomeViolation(nodeManifest({ biomeDep: `^${FLEET_BIOME_VERSION}` })), undefined);
+});
+
+test('biome-linter warns (not errors) when a node repo has no biome dep', () => {
+  // Otherwise-conformant repo on ESLint → only the biome-linter warn fires, and
+  // a warn must not fail overall conformance.
+  const m = { ...goodManifest(), packageJson: { devDependencies: { eslint: '^9' } } };
+  const r = evaluateStandard(m);
+  const v = r.violations.find((x) => x.id === 'biome-linter');
+  assert.ok(v, 'expected a biome-linter violation');
+  assert.equal(v.severity, 'warn');
+  assert.match(v.detail.join(' '), /no @biomejs\/biome/);
+  assert.equal(r.ok, true, 'warn-severity biome gap must not fail conformance');
+});
+
+test('biome-linter warns when biome is declared but no biome.json', () => {
+  const v = biomeViolation(nodeManifest({ biomeDep: FLEET_BIOME_VERSION, hasBiomeJson: false }));
+  assert.ok(v);
+  assert.match(v.detail.join(' '), /no biome\.json/);
+});
+
+test('biome-linter warns on version drift from the fleet pin', () => {
+  const v = biomeViolation(nodeManifest({ biomeDep: '2.3.0' }));
+  assert.ok(v);
+  assert.match(v.detail.join(' '), new RegExp(`fleet tracks ${FLEET_BIOME_VERSION.replace(/\./g, '\\.')}`));
+});
+
+test('biome.jsonc satisfies the config requirement too', () => {
+  const m = {
+    hasFile: (p) => p === 'biome.jsonc',
+    gitignore: '',
+    packageJson: { devDependencies: { '@biomejs/biome': FLEET_BIOME_VERSION } },
+  };
+  assert.equal(biomeViolation(m), undefined);
+});