diff --git a/.changeset/attest-launch-for-pod.md b/.changeset/attest-launch-for-pod.md
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+++ b/.changeset/attest-launch-for-pod.md
@@ -0,0 +1,11 @@
+---
+---
+
+Add `room/launch-attest.ts` — the L2 launch-attestation orchestration step:
+`podLaunchManifest(pod)` (the pod's resolved door grants = authority held) +
+`attestLaunchForPod(pod)` which attests the manifest via the keeper door
+(`runKeeperDoorAttestLaunch`) and stores the signed L2 content-addressed
+(`storeLaunchAttestation`), returning the `l2LaunchDigest` the box's keeper push
+links. Effects are injected seams (offline-testable). The live `playPod` flow
+calls this once the keeper door is up, then projects `l2LaunchDigest` into the box
+env. No release.
diff --git a/packages/prx/src/room/launch-attest.ts b/packages/prx/src/room/launch-attest.ts
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index 00000000..6a29ca92
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diff --git a/packages/prx/test/room/launch-attest.test.ts b/packages/prx/test/room/launch-attest.test.ts
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+++ b/packages/prx/test/room/launch-attest.test.ts
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+// The launch-attestation orchestration step: manifest = the pod's held doors,
+// attested via the keeper door + stored; returns the l2LaunchDigest.
+import { describe, test, expect } from "bun:test";
+
+import { perRepoPod } from "../../src/room/per-repo-pod.ts";
+import { attestLaunchForPod, podLaunchManifest } from "../../src/room/launch-attest.ts";
+
+describe("podLaunchManifest", () => {
+  test("is the pod's resolved door grants, deterministically ordered", () => {
+    const m = podLaunchManifest(perRepoPod);
+    expect(m.pod).toBe(perRepoPod.name);
+    expect(Array.isArray(m.doors)).toBe(true);
+    // each door names the authority the box holds
+    for (const d of m.doors) {
+      expect(typeof d.door).toBe("string");
+      expect(typeof d.capability).toBe("string");
+      expect(typeof d.consumer).toBe("string");
+    }
+    // deterministic (same input → same manifest)
+    expect(podLaunchManifest(perRepoPod)).toEqual(m);
+  });
+});
+
+describe("attestLaunchForPod", () => {
+  test("attests the manifest via the keeper door, stores the L2, returns the digest", async () => {
+    let sent: { subject: string; manifest: unknown } | undefined;
+    let storedL2: unknown;
+    const digest = await attestLaunchForPod(perRepoPod, {
+      attestLaunch: async (opts) => {
+        sent = opts;
+        return {
+          subject: opts.subject,
+          manifestDigest: "m".repeat(64),
+          l2LaunchDigest: "l".repeat(64),
+          attestation: { statement: { x: 1 }, signature: "sig" },
+        };
+      },
+      store: async (l2) => {
+        storedL2 = l2;
+        return "stored-digest";
+      },
+    });
+    expect(sent?.subject).toBe(perRepoPod.name);
+    expect(sent?.manifest).toEqual(podLaunchManifest(perRepoPod));
+    expect(storedL2).toEqual({ statement: { x: 1 }, signature: "sig" });
+    expect(digest).toBe("stored-digest");
+  });
+});