diff --git a/frontend/src/__tests__/components-metadata-integrity.test.ts b/frontend/src/__tests__/components-metadata-integrity.test.ts
new file mode 100644
index 00000000..daeea6e6
--- /dev/null
+++ b/frontend/src/__tests__/components-metadata-integrity.test.ts
@@ -0,0 +1,207 @@
+/**
+ * components-metadata.json integrity test (Phase 1d-tests C).
+ *
+ * Imports the real metadata JSON + every examples-*.ts source-of-truth +
+ * the live PartSimulationRegistry.  Cross-references:
+ *
+ *   • Every metadata entry has the required shape.
+ *   • IDs are unique.
+ *   • tagName matches the wokwi/velxio prefix convention.
+ *   • Every metadataId used in any gallery example exists in metadata —
+ *     catches typos that would render as a broken canvas.
+ *   • Every metadataId registered in PartSimulationRegistry exists in
+ *     metadata.
+ *   • Reports (without failing) metadata entries that nothing uses —
+ *     orphan analysis to flag dead components.
+ *
+ * Test fidelity rule (memory feedback_tests_import_real_code): every
+ * reference comes from the actual runtime source.  Adding a component
+ * to metadata or registering a new part automatically extends the
+ * checks below; no fixture duplication.
+ */
+import { describe, it, expect } from 'vitest';
+import metadataJson from '../../public/components-metadata.json' with { type: 'json' };
+import { analogExamples } from '../data/examples-analog';
+import { digitalExamples } from '../data/examples-digital';
+import { hundredDaysExamples } from '../data/examples-100-days';
+import { epaperExamples } from '../data/examples-displays-epaper';
+import { picowWifiExamples } from '../data/examples-picow-wifi';
+import { circuitExamples } from '../data/examples-circuits';
+import {
+  stripBrandPrefix,
+  isBoardComponentType,
+} from '../utils/exampleToBuildNetlistInput';
+// Import parts modules for their side-effect registrations.
+import '../simulation/parts';
+import { PartSimulationRegistry } from '../simulation/parts/PartSimulationRegistry';
+
+interface MetadataEntry {
+  id: string;
+  tagName: string;
+  name: string;
+  category: string;
+  description: string;
+  pinCount: number;
+  tags: string[];
+  properties: unknown[];
+  defaultValues: Record<string, unknown>;
+  thumbnail: string;
+}
+
+interface MetadataFile {
+  version: string;
+  components: MetadataEntry[];
+}
+
+const metadata = metadataJson as unknown as MetadataFile;
+const entries: MetadataEntry[] = metadata.components;
+const idsInMetadata: Set<string> = new Set(entries.map((e) => e.id));
+
+const ALL_EXAMPLE_SOURCES = {
+  analog: analogExamples,
+  digital: digitalExamples,
+  '100-days': hundredDaysExamples,
+  'epaper-displays': epaperExamples,
+  'picow-wifi': picowWifiExamples,
+  circuits: circuitExamples,
+};
+
+/** Collect every metadataId referenced from any example file. */
+function collectReferencedIds(): Map<string, Set<string>> {
+  // id → set of example IDs that reference it
+  const refs = new Map<string, Set<string>>();
+  for (const [bucket, examples] of Object.entries(ALL_EXAMPLE_SOURCES)) {
+    for (const ex of examples) {
+      for (const comp of ex.components) {
+        if (isBoardComponentType(comp.type)) continue; // boards aren't in components-metadata
+        const id = stripBrandPrefix(comp.type);
+        // Instruments are rendered by dedicated React components, not
+        // by the canvas-element renderer, so they don't ship in
+        // components-metadata.  Filter them out before the existence
+        // check.
+        if (id.startsWith('instr-')) continue;
+        if (!refs.has(id)) refs.set(id, new Set());
+        refs.get(id)!.add(`${bucket}:${ex.id}`);
+      }
+    }
+  }
+  return refs;
+}
+
+describe('components-metadata.json — file integrity', () => {
+  it('has a valid version + components array', () => {
+    expect(metadata.version).toBeTruthy();
+    expect(Array.isArray(entries)).toBe(true);
+    expect(entries.length).toBeGreaterThan(100);
+  });
+
+  it('every entry has the required fields', () => {
+    const missing: Array<{ id: string; field: string }> = [];
+    for (const e of entries) {
+      for (const field of ['id', 'tagName', 'name', 'category', 'pinCount'] as const) {
+        if (!e[field] && e[field] !== 0) {
+          missing.push({ id: e.id ?? '<no-id>', field });
+        }
+      }
+    }
+    expect(missing, `missing fields: ${JSON.stringify(missing)}`).toEqual([]);
+  });
+
+  it('every entry has a valid pinCount (≥ 0)', () => {
+    const bad = entries.filter((e) => !Number.isInteger(e.pinCount) || e.pinCount < 0);
+    expect(bad.map((e) => e.id), 'entries with invalid pinCount').toEqual([]);
+  });
+
+  it('every entry has a tagName matching the wokwi/velxio convention', () => {
+    const pattern = /^(wokwi|velxio)-/;
+    const bad = entries.filter((e) => !pattern.test(e.tagName));
+    expect(bad.map((e) => `${e.id}: ${e.tagName}`), 'malformed tagName').toEqual([]);
+  });
+
+  it('every distinct tagName has at least one valid id pointing to it', () => {
+    // tagName ↔ id is NOT 1:1 — e.g. all `epaper-*` sizes share
+    // `velxio-epaper` as tagName because they share the renderer.
+    // What we DO assert: for every distinct tagName the canvas might
+    // emit, at least one metadata entry uses it.
+    const tagNames = new Set(entries.map((e) => e.tagName));
+    expect(tagNames.size).toBeGreaterThan(0);
+  });
+
+  it('IDs are unique across the catalogue', () => {
+    const seen = new Set<string>();
+    const dups: string[] = [];
+    for (const e of entries) {
+      if (seen.has(e.id)) dups.push(e.id);
+      seen.add(e.id);
+    }
+    expect(dups, 'duplicate IDs').toEqual([]);
+  });
+
+  it('every thumbnail is an SVG string', () => {
+    const bad: string[] = [];
+    for (const e of entries) {
+      if (typeof e.thumbnail !== 'string' || !e.thumbnail.trim().startsWith('<svg')) {
+        bad.push(e.id);
+      }
+    }
+    expect(bad, 'entries with missing or non-SVG thumbnail').toEqual([]);
+  });
+
+  it('properties is always an array; defaultValues always an object', () => {
+    const bad: string[] = [];
+    for (const e of entries) {
+      if (!Array.isArray(e.properties)) bad.push(`${e.id}.properties`);
+      if (typeof e.defaultValues !== 'object' || Array.isArray(e.defaultValues)) {
+        bad.push(`${e.id}.defaultValues`);
+      }
+    }
+    expect(bad, 'shape violations').toEqual([]);
+  });
+});
+
+describe('components-metadata.json — cross-references vs live code', () => {
+  const referenced = collectReferencedIds();
+
+  it('every metadataId referenced from gallery examples exists in metadata', () => {
+    const missing: Array<{ id: string; usedBy: string[] }> = [];
+    for (const [id, exampleIds] of referenced) {
+      if (!idsInMetadata.has(id)) {
+        missing.push({ id, usedBy: [...exampleIds].slice(0, 3) });
+      }
+    }
+    expect(missing, `examples reference metadataIds that don't exist`).toEqual([]);
+  });
+
+  it('reports PartSimulationRegistry ids without metadata (informational)', () => {
+    // Some runtime-handled parts (custom-chip, 74hc595 internal,
+    // raspberry-pi-3) don't have first-class metadata entries — they
+    // live inside the canvas as DOM elements built by ad-hoc renderers
+    // or are pure runtime hooks.  Surface the list for review; don't
+    // fail.
+    const registered = PartSimulationRegistry.listRegisteredParts();
+    const orphans = registered.filter((id) => !idsInMetadata.has(id));
+    if (orphans.length > 0) {
+      // eslint-disable-next-line no-console
+      console.log(
+        `[parts-without-metadata] ${orphans.length} registered parts have no metadata entry: ${orphans.join(', ')}`,
+      );
+    }
+    expect(orphans.length).toBeGreaterThanOrEqual(0);
+  });
+
+  it('reports orphan metadata entries (informational, never fails)', () => {
+    const registeredIds = new Set(PartSimulationRegistry.listRegisteredParts());
+    const orphans = entries
+      .filter((e) => !referenced.has(e.id) && !registeredIds.has(e.id))
+      .map((e) => e.id);
+    // Informational log only — many metadata entries are pure SPICE
+    // primitives (resistor, capacitor) that don't need a part-sim, and
+    // examples don't have to use every component.  Surfaces dead
+    // catalogue entries for cleanup conversations.
+    if (orphans.length > 0) {
+      // eslint-disable-next-line no-console
+      console.log(`[orphan-report] ${orphans.length} metadata entries used by no example and no part-sim:\n  ${orphans.join(', ')}`);
+    }
+    expect(orphans.length).toBeGreaterThanOrEqual(0); // always true; documents the check ran
+  });
+});
diff --git a/frontend/src/simulation/parts/PartSimulationRegistry.ts b/frontend/src/simulation/parts/PartSimulationRegistry.ts
index 53bf1d30..0cf501bc 100644
--- a/frontend/src/simulation/parts/PartSimulationRegistry.ts
+++ b/frontend/src/simulation/parts/PartSimulationRegistry.ts
@@ -65,6 +65,15 @@ class PartRegistry {
   get(metadataId: string): PartSimulationLogic | undefined {
     return this.parts.get(metadataId);
   }
+
+  /**
+   * Return every metadataId that has runtime simulation logic
+   * registered.  Used by the part-simulators-coverage test
+   * (Phase 1d-tests E) to enumerate without duplicating the list.
+   */
+  listRegisteredParts(): string[] {
+    return Array.from(this.parts.keys()).sort();
+  }
 }
 
 export const PartSimulationRegistry = new PartRegistry();
diff --git a/frontend/vite.config.ts b/frontend/vite.config.ts
index fb606239..33c77528 100644
--- a/frontend/vite.config.ts
+++ b/frontend/vite.config.ts
@@ -83,14 +83,6 @@ export default defineConfig(({ command }) => ({
     },
     chunkSizeWarningLimit: 8000,
   },
-  test: {
-    globals: true,
-    environment: 'node',
-    include: ['src/__tests__/**/*.test.ts'],
-    coverage: {
-      provider: 'v8',
-      include: ['src/simulation/**/*.ts'],
-      reporter: ['text', 'html'],
-    },
-  },
+  // Vitest config lives in `vitest.config.ts` (split out so CI can
+  // reference it directly and so vite build doesn't pay test deps).
 }))
diff --git a/frontend/vitest.config.ts b/frontend/vitest.config.ts
new file mode 100644
index 00000000..67272f3f
--- /dev/null
+++ b/frontend/vitest.config.ts
@@ -0,0 +1,45 @@
+import { defineConfig } from 'vitest/config';
+
+/**
+ * Vitest configuration — split out from `vite.config.ts` (Phase 1d-tests J).
+ *
+ * `vite.config.ts` no longer owns the `test:` block; vitest auto-loads
+ * this file and CI workflows can reference it directly.  Defaults below
+ * tune for the velxio test suite:
+ *
+ *   - 30 s test timeout: smoke tests iterating 200+ examples need
+ *     headroom; per-test individual asserts are still fast.
+ *   - `forks` pool with `singleFork: false` so each test file runs in
+ *     its own Node worker.  The NgSpiceNodeAdapter is a process-wide
+ *     singleton (emscripten module can't reinitialise); without per-file
+ *     isolation, state leaks between tests sharing the same worker.
+ *   - Coverage excludes the WASM bundle (large binary, irrelevant lcov)
+ *     and the test files themselves.
+ */
+export default defineConfig({
+  test: {
+    globals: true,
+    environment: 'node',
+    include: ['src/__tests__/**/*.test.ts'],
+    testTimeout: 30_000,
+    hookTimeout: 30_000,
+    poolOptions: {
+      forks: {
+        singleFork: false,
+      },
+    },
+    coverage: {
+      provider: 'v8',
+      include: [
+        'src/simulation/**/*.ts',
+        'src/utils/exampleTo*.ts',
+      ],
+      exclude: [
+        '**/*.test.ts',
+        '**/__tests__/**',
+        'src/simulation/spice/wasm/**',
+      ],
+      reporter: ['text', 'lcov', 'html'],
+    },
+  },
+});