diff --git a/scripts/conformance.mjs b/scripts/conformance.mjs
new file mode 100644
index 0000000..397d3a2
--- /dev/null
+++ b/scripts/conformance.mjs
@@ -0,0 +1,102 @@
+#!/usr/bin/env node
+/**
+ * pnpm conformance — cross-feature drift gate.
+ *
+ * Walks every `packages/*\/src/feature.manifest.ts`, reuses the AST parser
+ * from `@repo/core-eslint` to extract per-use-case publishes/consumes,
+ * builds global publish + consume sets across all features, and fails on:
+ *
+ *   - Orphan consumer: a feature declares `consumes: ["X"]` but no
+ *     feature publishes "X".
+ *
+ * Exits 0 on success, 1 on any violation. Prints a tabular summary of
+ * the event graph for transparency.
+ */
+import fs from "node:fs";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import { parseManifestUseCases } from "../packages/core-eslint/rules/_manifest-ast.js";
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+const REPO_ROOT = path.resolve(__dirname, "..");
+
+export function findAllManifests(repoRoot = REPO_ROOT) {
+  const packagesDir = path.join(repoRoot, "packages");
+  if (!fs.existsSync(packagesDir)) return [];
+  const out = [];
+  for (const entry of fs.readdirSync(packagesDir)) {
+    const manifestPath = path.join(packagesDir, entry, "src", "feature.manifest.ts");
+    if (fs.existsSync(manifestPath)) {
+      out.push({ feature: entry, path: manifestPath });
+    }
+  }
+  return out;
+}
+
+export function buildEventGraph(manifests) {
+  const graph = new Map();
+  for (const { feature, path: manifestPath } of manifests) {
+    const useCases = parseManifestUseCases(manifestPath);
+    if (!useCases) continue;
+    for (const [useCase, entry] of Object.entries(useCases)) {
+      for (const event of entry.publishes) {
+        if (!graph.has(event)) graph.set(event, { publishers: [], consumers: [] });
+        graph.get(event).publishers.push({ feature, useCase });
+      }
+      for (const event of entry.consumes) {
+        if (!graph.has(event)) graph.set(event, { publishers: [], consumers: [] });
+        graph.get(event).consumers.push({ feature, useCase });
+      }
+    }
+  }
+  return graph;
+}
+
+export function findOrphanConsumers(graph) {
+  const orphans = [];
+  for (const [event, { publishers, consumers }] of graph.entries()) {
+    if (consumers.length > 0 && publishers.length === 0) {
+      orphans.push({ event, consumers });
+    }
+  }
+  return orphans;
+}
+
+function main() {
+  const manifests = findAllManifests();
+  console.log(`Found ${manifests.length} feature manifest(s):`);
+  for (const { feature } of manifests) console.log(`  - ${feature}`);
+  console.log();
+
+  const graph = buildEventGraph(manifests);
+  if (graph.size === 0) {
+    console.log("No cross-feature events declared yet — nothing to check.");
+    process.exit(0);
+  }
+
+  console.log(`Event graph (${graph.size} event(s)):`);
+  for (const [event, { publishers, consumers }] of graph.entries()) {
+    console.log(`  ${event}`);
+    console.log(`    publishers: ${publishers.length === 0 ? "(none)" : publishers.map((p) => `${p.feature}.${p.useCase}`).join(", ")}`);
+    console.log(`    consumers:  ${consumers.length === 0 ? "(none)" : consumers.map((c) => `${c.feature}.${c.useCase}`).join(", ")}`);
+  }
+  console.log();
+
+  const orphans = findOrphanConsumers(graph);
+  if (orphans.length === 0) {
+    console.log("✓ pnpm conformance — passed");
+    process.exit(0);
+  }
+  console.error(`✗ pnpm conformance — ${orphans.length} orphan consumer(s):`);
+  for (const { event, consumers } of orphans) {
+    console.error(`  ${event}`);
+    for (const c of consumers) {
+      console.error(`    consumed by ${c.feature}.${c.useCase}, but no feature publishes it`);
+    }
+  }
+  process.exit(1);
+}
+
+if (import.meta.url === `file://${process.argv[1]}`) {
+  main();
+}
diff --git a/scripts/conformance.test.mjs b/scripts/conformance.test.mjs
new file mode 100644
index 0000000..3ebbc0f
--- /dev/null
+++ b/scripts/conformance.test.mjs
@@ -0,0 +1,83 @@
+import { describe, it, expect } from "vitest";
+import path from "node:path";
+import os from "node:os";
+import fs from "node:fs";
+import { findAllManifests, buildEventGraph, findOrphanConsumers } from "./conformance.mjs";
+
+function makeRepo(features) {
+  const root = fs.mkdtempSync(path.join(os.tmpdir(), "conformance-"));
+  for (const [name, useCases] of Object.entries(features)) {
+    const dir = path.join(root, "packages", name, "src");
+    fs.mkdirSync(dir, { recursive: true });
+    const useCasesStr = Object.entries(useCases)
+      .map(([ucName, uc]) =>
+        `    ${ucName}: { mutates: ${uc.mutates ?? false}, audits: [], publishes: [${(uc.publishes ?? []).map((p) => `"${p}"`).join(", ")}], consumes: [${(uc.consumes ?? []).map((c) => `"${c}"`).join(", ")}] },`,
+      )
+      .join("\n");
+    fs.writeFileSync(
+      path.join(dir, "feature.manifest.ts"),
+      `export const ${name}Manifest = defineFeature({
+  name: "${name}",
+  requiredCores: [],
+  useCases: {
+${useCasesStr}
+  },
+  realtimeChannels: [],
+  jobs: [],
+} as const);`,
+    );
+  }
+  return root;
+}
+
+describe("conformance script", () => {
+  describe("findAllManifests", () => {
+    it("returns one entry per feature with a manifest", () => {
+      const root = makeRepo({
+        auth: { signIn: {} },
+        blog: { getArticles: {} },
+      });
+      const ms = findAllManifests(root);
+      expect(ms.map((m) => m.feature).sort()).toEqual(["auth", "blog"]);
+    });
+
+    it("skips packages without a manifest", () => {
+      const root = fs.mkdtempSync(path.join(os.tmpdir(), "conformance-empty-"));
+      fs.mkdirSync(path.join(root, "packages", "no-manifest", "src"), { recursive: true });
+      expect(findAllManifests(root)).toEqual([]);
+    });
+  });
+
+  describe("buildEventGraph + findOrphanConsumers", () => {
+    it("finds zero orphans when consumers and publishers line up", () => {
+      const root = makeRepo({
+        auth: { signUp: { mutates: true, publishes: ["auth.signed-up"] } },
+        marketing: { onAuthSignedUp: { consumes: ["auth.signed-up"] } },
+      });
+      const manifests = findAllManifests(root);
+      const graph = buildEventGraph(manifests);
+      expect(findOrphanConsumers(graph)).toEqual([]);
+    });
+
+    it("flags orphan consumers", () => {
+      const root = makeRepo({
+        marketing: { onAuthSignedUp: { consumes: ["auth.signed-up"] } },
+      });
+      const manifests = findAllManifests(root);
+      const graph = buildEventGraph(manifests);
+      const orphans = findOrphanConsumers(graph);
+      expect(orphans).toHaveLength(1);
+      expect(orphans[0].event).toBe("auth.signed-up");
+      expect(orphans[0].consumers).toEqual([{ feature: "marketing", useCase: "onAuthSignedUp" }]);
+    });
+
+    it("treats publish-only events as fine (no consumers is not an orphan)", () => {
+      const root = makeRepo({
+        auth: { signUp: { mutates: true, publishes: ["auth.signed-up"] } },
+      });
+      const manifests = findAllManifests(root);
+      const graph = buildEventGraph(manifests);
+      expect(findOrphanConsumers(graph)).toEqual([]);
+    });
+  });
+});