diff --git a/.gitignore b/.gitignore
index 9299475b7..b470644a6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -87,5 +87,10 @@ next-env.d.ts
 .audit-*.mjs
 
 
-# Isolated development worktrees
+# Isolated development worktrees. `/.wt-*/` is the convention actually in use;
+# each one is a full copy of the tree with its own node_modules, so leaving it
+# untracked-but-visible means one `git add -A` commits the repository eleven
+# times over. The same two names are excluded from eslint and vitest, for the
+# same reason in a different tool.
+/.wt-*/
 /.worktrees/
\ No newline at end of file
diff --git a/eslint.config.mjs b/eslint.config.mjs
index 82fa8cfae..9f0e9130f 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -16,6 +16,10 @@ const eslintConfig = defineConfig([
     // v1.31.4 — ignore local tool worktrees so a worktree on another
     // commit cannot poison `pnpm lint` locally.
     // CI never sees these paths; the rules protect the dev environment.
+    // `.wt-*` is the convention actually in use; the two names below predate
+    // it. Without the first pattern `pnpm lint` walks every worktree in the
+    // root, which is both slow and exactly the poisoning this list prevents.
+    ".wt-*/**",
     ".claude/**",
     ".worktrees/**",
     // The project-local ESLint rule plugin is CommonJS (require/module
@@ -32,6 +36,21 @@ const eslintConfig = defineConfig([
   {
     plugins: { healthlog: healthlogPlugin },
     rules: {
+      // The codebase already marks a deliberately unused binding by prefixing
+      // it with an underscore — a required-but-ignored route handler argument,
+      // a mock signature that has to match the real one. The rule did not know
+      // that convention, so seven such bindings warned and `pnpm lint` could
+      // not be read as pass/fail. Teaching it the convention is what makes a
+      // real warning visible again.
+      "@typescript-eslint/no-unused-vars": [
+        "warn",
+        {
+          argsIgnorePattern: "^_",
+          varsIgnorePattern: "^_",
+          caughtErrorsIgnorePattern: "^_",
+          destructuredArrayIgnorePattern: "^_",
+        },
+      ],
       "healthlog/queryKey-factory": "error",
       // v1.5.6 — every outbound fetch under src/lib + src/app must route
       // through the safeFetch wrapper (manual-redirect + timeout, and the
diff --git a/src/app/api/feature-flags/route.ts b/src/app/api/feature-flags/route.ts
index e92422307..a8d9928db 100644
--- a/src/app/api/feature-flags/route.ts
+++ b/src/app/api/feature-flags/route.ts
@@ -40,7 +40,6 @@ import { apiSuccess } from "@/lib/api-response";
 import { getAssistantFlags } from "@/lib/feature-flags";
 import { annotate } from "@/lib/logging/context";
 
-// eslint-disable-next-line @typescript-eslint/no-unused-vars
 export const GET = apiHandler(async (_request: NextRequest) => {
   await requireAuth();
   annotate({ action: { name: "feature-flags.read" } });
diff --git a/src/app/api/measurement-categories/route.ts b/src/app/api/measurement-categories/route.ts
index ef7f55f56..597322014 100644
--- a/src/app/api/measurement-categories/route.ts
+++ b/src/app/api/measurement-categories/route.ts
@@ -62,7 +62,6 @@ const CATEGORY_ORDER: readonly MeasurementCategory[] = [
   "metabolic",
 ] as const;
 
-// eslint-disable-next-line @typescript-eslint/no-unused-vars
 export const GET = apiHandler(async (_request: NextRequest) => {
   await requireAuth();
 
diff --git a/src/app/api/sync/state/route.ts b/src/app/api/sync/state/route.ts
index dd9ce0a4e..b45e269a1 100644
--- a/src/app/api/sync/state/route.ts
+++ b/src/app/api/sync/state/route.ts
@@ -43,7 +43,6 @@ import {
   TOMBSTONE_RETENTION_DAYS,
 } from "@/lib/auth/native-client";
 
-// eslint-disable-next-line @typescript-eslint/no-unused-vars
 export const GET = apiHandler(async (_request: NextRequest) => {
   const { user } = await requireAuth();
 
diff --git a/src/components/onboarding/goals-chip-picker.tsx b/src/components/onboarding/goals-chip-picker.tsx
index a637858a9..a1a64d06a 100644
--- a/src/components/onboarding/goals-chip-picker.tsx
+++ b/src/components/onboarding/goals-chip-picker.tsx
@@ -97,7 +97,6 @@ export interface GoalsChipPickerProps {
   userId: string;
 }
 
-// eslint-disable-next-line @typescript-eslint/no-unused-vars
 export function GoalsChipPicker({ userId: _userId }: GoalsChipPickerProps) {
   const { t } = useTranslations();
   const router = useRouter();
diff --git a/src/lib/cycle/gate.ts b/src/lib/cycle/gate.ts
index 839ff1e02..c198a7361 100644
--- a/src/lib/cycle/gate.ts
+++ b/src/lib/cycle/gate.ts
@@ -88,7 +88,6 @@ export type CycleGateResult =
  */
 export async function requireCycleEnabled(
   userId: string,
-  // eslint-disable-next-line @typescript-eslint/no-unused-vars
   _gender: string | null | undefined,
 ): Promise<CycleGateResult> {
   const [profile, available] = await Promise.all([
diff --git a/vitest.config.mts b/vitest.config.mts
index 777007d6f..e19110a15 100644
--- a/vitest.config.mts
+++ b/vitest.config.mts
@@ -31,8 +31,13 @@ export default defineConfig({
       "tests/integration/**",
       // Playwright E2E suite — driven separately via `pnpm e2e`.
       "e2e/**",
-      // Local agent worktrees create copies of `src/` under `.claude/`
-      // or `.worktrees/`; vitest must not collect stale duplicate suites.
+      // Local tool worktrees create full copies of `src/` in the repo root;
+      // vitest must not collect stale duplicate suites from them. The copies
+      // also carry their own `node_modules`, so a collected duplicate drags in
+      // a SECOND React instance and fails in ways that have nothing to do with
+      // the working tree. `.wt-*` is the convention actually in use — the two
+      // names below predate it and are kept because both still occur.
+      ".wt-*/**",
       ".claude/worktrees/**",
       ".worktrees/**",
     ],