diff --git a/.changeset/keeper-door-guest-room-model.md b/.changeset/keeper-door-guest-room-model.md
new file mode 100644
index 00000000..6e6132d2
--- /dev/null
+++ b/.changeset/keeper-door-guest-room-model.md
@@ -0,0 +1,10 @@
+---
+---
+
+A1 of the prx→guest-room convergence: add `@bounded-systems/guest-room` as a prx
+dependency (github dep until it publishes to JSR) and describe the keeper door
+through guest-room's capability model — a `DoorCatalog` preset + a rulebook
+rendered by guest-room's `resolveDoor`/`grantedDoorLines`/`deniedDoorSection`.
+First real dependency edge from prx onto the flagship runtime. Additive: the
+keeperd transport is unchanged; the keeper endpoint env stays sourced from
+`keeperd/endpoint.ts`. No public API or behavior change, no release.
diff --git a/bun.lock b/bun.lock
index a9bccf02..a4fd7800 100644
--- a/bun.lock
+++ b/bun.lock
@@ -45,6 +45,7 @@
         "@bounded-systems/gh": "npm:@jsr/bounded-systems__gh@^0.1.0",
         "@bounded-systems/git": "npm:@jsr/bounded-systems__git@^0.1.0",
         "@bounded-systems/github-budget": "npm:@jsr/bounded-systems__github-budget@^0.1.0",
+        "@bounded-systems/guest-room": "npm:@jsr/bounded-systems__guest-room@^0.1.0",
         "@bounded-systems/host": "npm:@jsr/bounded-systems__host@^0.2.0",
         "@bounded-systems/machine-schema": "npm:@jsr/bounded-systems__machine-schema@^0.2.0",
         "@bounded-systems/policy": "npm:@jsr/bounded-systems__policy@^0.2.0",
@@ -129,6 +130,8 @@
 
     "@bounded-systems/github-budget": ["@jsr/bounded-systems__github-budget@0.1.0", "https://npm.jsr.io/~/11/@jsr/bounded-systems__github-budget/0.1.0.tgz", { "dependencies": { "@jsr/bounded-systems__audit-context": "^0.2.0", "@jsr/bounded-systems__env": "^0.2.0", "@jsr/bounded-systems__proc": "^0.2.0", "zod": "^4.4.3" } }, "sha512-7lBN1nN6V3AGuBwF0TjepWklCvPX4FD7w1XJezhZaP7k1h6nGKB1xheu8RWPCWPGfV8DmePWpN2L8Znaugcm2w=="],
 
+    "@bounded-systems/guest-room": ["@jsr/bounded-systems__guest-room@0.1.0", "https://npm.jsr.io/~/11/@jsr/bounded-systems__guest-room/0.1.0.tgz", {}, "sha512-B2x+wyCyJT9ZNLmN64OS9SL81eqsFPmnWmL0A54Ic++X6GYqbwVdvWdHiE4lI8Bm3kP0mirLpIiP67ICkgaGOg=="],
+
     "@bounded-systems/host": ["@jsr/bounded-systems__host@0.2.0", "https://npm.jsr.io/~/11/@jsr/bounded-systems__host/0.2.0.tgz", { "dependencies": { "@jsr/bounded-systems__env": "^0.2.0" } }, "sha512-N5uc3Du3jzmlgX3tP0gnIZwOYXGOYYiU+wTBpiG6iYpfPG9WVoFWWoZkcb79QH93AaERnJUhrw2yKSq13VJEAg=="],
 
     "@bounded-systems/machine-schema": ["@jsr/bounded-systems__machine-schema@0.2.0", "https://npm.jsr.io/~/11/@jsr/bounded-systems__machine-schema/0.2.0.tgz", { "dependencies": { "zod": "^4.4.3" } }, "sha512-Ttvrh+Gj+IWkdq0fO6Db1OVuvMB5nRUOgKuvEUX7GfJK8AAU/dvsu9bq8sZCk67XGZl1diQ6BrflIgA5NxzqJg=="],
diff --git a/packages/prx/package.json b/packages/prx/package.json
index 5a7d1d6d..bf267b5e 100644
--- a/packages/prx/package.json
+++ b/packages/prx/package.json
@@ -25,6 +25,7 @@
     "@bounded-systems/gh": "npm:@jsr/bounded-systems__gh@^0.1.0",
     "@bounded-systems/git": "npm:@jsr/bounded-systems__git@^0.1.0",
     "@bounded-systems/github-budget": "npm:@jsr/bounded-systems__github-budget@^0.1.0",
+    "@bounded-systems/guest-room": "npm:@jsr/bounded-systems__guest-room@^0.1.0",
     "@bounded-systems/host": "npm:@jsr/bounded-systems__host@^0.2.0",
     "@bounded-systems/machine-schema": "npm:@jsr/bounded-systems__machine-schema@^0.2.0",
     "@bounded-systems/policy": "npm:@jsr/bounded-systems__policy@^0.2.0",
diff --git a/packages/prx/src/door/guest-room-catalog.ts b/packages/prx/src/door/guest-room-catalog.ts
new file mode 100644
index 00000000..1856eb32
--- /dev/null
+++ b/packages/prx/src/door/guest-room-catalog.ts
@@ -0,0 +1,66 @@
+// A1 of the prx→guest-room convergence (see .github-private
+// docs/convergence-prx-claude-box.md): describe prx's keeper door using the
+// published @bounded-systems/guest-room capability model instead of an ad-hoc
+// local description. This is the first real dependency edge from prx onto
+// guest-room — the same model that powers claude-box now describes prx's door.
+//
+// Scope: ADDITIVE. It does not change the keeperd transport (still the bespoke
+// client in ../keeperd/); it makes the door's *definition + rulebook* come from
+// the guest-room contract. The endpoint env stays sourced from
+// ../keeperd/endpoint.ts, so there is still one source of truth for the socket.
+
+import {
+  capabilityPreamble,
+  deniedDoors,
+  type DoorCatalog,
+  type DoorGrant,
+  deniedDoorSection,
+  type Env,
+  grantedDoorLines,
+  resolveDoor,
+} from "@bounded-systems/guest-room";
+import { processEnv } from "@bounded-systems/env";
+
+import { DEFAULT_LOCAL_KEEPER_SOCKET } from "../keeperd/endpoint.ts";
+
+/**
+ * prx's door catalog, expressed in the guest-room model. Today it is the keeper
+ * door (signed git-writes via keeperd); the other prx doors (beads, …) join here
+ * as they move onto the runtime.
+ */
+export const prxDoorCatalog: DoorCatalog = {
+  keeper: {
+    flag: "--keeper",
+    inBox: "/run/prx/doors/keeperd.sock",
+    env: "PRX_KEEPER_SOCKET",
+    hostDefault: DEFAULT_LOCAL_KEEPER_SOCKET,
+    grants: "signed git writes via keeperd",
+    use: "Route every git write through the keeper door; keeperd imports the commit and performs the signed push.",
+    deny: "No git-write authority in this room — relaunch with the keeper door.",
+  },
+};
+
+/** Resolve prx's keeper door to a concrete grant via the guest-room engine. */
+export function keeperDoorGrant(env: Env = processEnv()): DoorGrant {
+  return resolveDoor(prxDoorCatalog, "keeper", undefined, env);
+}
+
+/**
+ * Render the honest rulebook for a prx room over the given granted doors, using
+ * guest-room's renderer: the capability preamble, a card per granted door, and
+ * the denied section — so the surface is honest about what is absent, not only
+ * what is present.
+ */
+export function renderPrxRulebook(
+  workcell: string,
+  grantedDoorNames: readonly string[],
+  env: Env = processEnv(),
+): string {
+  const granted = grantedDoorNames.map((n) => resolveDoor(prxDoorCatalog, n, undefined, env));
+  const denied = deniedDoors(prxDoorCatalog, new Set(grantedDoorNames));
+  return [
+    ...capabilityPreamble(workcell),
+    ...grantedDoorLines(granted),
+    ...deniedDoorSection(denied),
+  ].join("\n");
+}
diff --git a/packages/prx/test/door/guest-room-catalog.test.ts b/packages/prx/test/door/guest-room-catalog.test.ts
new file mode 100644
index 00000000..bdccb3a1
--- /dev/null
+++ b/packages/prx/test/door/guest-room-catalog.test.ts
@@ -0,0 +1,28 @@
+// A1: prx describes its keeper door through the guest-room capability model.
+import { describe, expect, test } from "bun:test";
+
+import {
+  keeperDoorGrant,
+  prxDoorCatalog,
+  renderPrxRulebook,
+} from "../../src/door/guest-room-catalog.ts";
+
+describe("prx keeper door via the guest-room model", () => {
+  test("the catalog defines the keeper door against the keeperd endpoint env", () => {
+    expect(prxDoorCatalog.keeper).toBeDefined();
+    expect(prxDoorCatalog.keeper!.env).toBe("PRX_KEEPER_SOCKET");
+  });
+
+  test("resolveDoor maps the preset into a concrete grant", () => {
+    const grant = keeperDoorGrant({ PRX_KEEPER_SOCKET: "/run/prx/doors/keeperd.sock" });
+    expect(grant.name).toBe("keeper");
+    expect(grant.env).toBe("PRX_KEEPER_SOCKET");
+    expect(grant.grants).toContain("signed git writes");
+  });
+
+  test("the rulebook is honest — a card for keeper, and a DENIED section", () => {
+    const book = renderPrxRulebook("prx", ["keeper"], { PRX_KEEPER_SOCKET: "/x.sock" });
+    expect(book).toContain("keeper: signed git writes");
+    expect(book).toContain("DENIED");
+  });
+});