feat: surface the job authority descriptor to subscribers (§7.6)

The runtime now populates `budget` (current per-currency counters) on
`job.subscribed`, alongside the `lease_constraints` it already sent, so an
observing principal can render a job's authority surface — the expiry clock
and budget gauge — without being the submitter. The cap is derivable from the
lease's `cost.budget` pattern; subsequent `cost.budget.remaining` metric events
keep the gauge live.

The client's `JobSubscription` now exposes the full descriptor:
`currentStatus`, `agent`, `lease`, `leaseConstraints`, `budget`, and
(submitter-only) `credentials`. Credentials remain redacted for non-submitters
per §14. Backward-compatible — only additive fields. Adds a runtime test
asserting an observer receives budget + lease_constraints but never credentials.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: Nick Ficano

.changeset/observer-authority-descriptor.md

@@ -0,0 +1,18 @@
+---
+"@agentruntimecontrolprotocol/runtime": minor
+"@agentruntimecontrolprotocol/client": minor
+---
+
+Surface a job's authority descriptor to subscribers (§7.6).
+
+The runtime now populates `budget` (current per-currency counters) on
+`job.subscribed`, alongside the `lease_constraints` it already sent, so an
+observing principal can render a job's authority surface — the expiry clock
+and budget gauge — without being the job's submitter. The cap is derivable
+from the lease's `cost.budget` pattern; subsequent `cost.budget.remaining`
+metric events keep the gauge live.
+
+The client's `JobSubscription` now exposes the full descriptor:
+`currentStatus`, `agent`, `lease`, `leaseConstraints`, `budget`, and
+(submitter-only) `credentials`. Credentials remain redacted for non-submitters
+per §14. Backward-compatible — only additive fields.

packages/client/src/client.ts

@@ -660,6 +660,12 @@ export class ARCPClient {
     const ack = await deferred.promise;
     return {
       jobId,
+      currentStatus: ack.current_status,
+      agent: ack.agent,
+      lease: ack.lease,
+      leaseConstraints: ack.lease_constraints,
+      budget: ack.budget,
+      credentials: ack.credentials,
       subscribedFrom: ack.subscribed_from,
       replayed: ack.replayed,
       unsubscribe: () => this.unsubscribe(jobId, sessionId),

packages/client/src/types.ts

@@ -7,6 +7,7 @@ import type {
   ClientIdentity,
   Envelope,
   JobResultPayload,
+  JobStateName,
   Lease,
   LeaseConstraints,
   Credential,
@@ -125,6 +126,26 @@ export interface JobHandle {
  */
 export interface JobSubscription {
   readonly jobId: JobId;
+  /** Job status at subscription time (§7.6). */
+  readonly currentStatus: JobStateName;
+  /** Resolved `name@version` (or bare name) the runtime is running. */
+  readonly agent: string;
+  /** Effective capability grants (§9.1). */
+  readonly lease: Lease;
+  /** v1.1 §9.5 — echoed lease constraints (currently `expires_at`), if any. */
+  readonly leaseConstraints: LeaseConstraints | undefined;
+  /**
+   * v1.1 §9.6 — current per-currency budget counters at subscription time,
+   * present when `cost.budget` is in the lease. The cap is derivable from the
+   * lease's `cost.budget` pattern; subsequent `cost.budget.remaining` metric
+   * events keep this live.
+   */
+  readonly budget: Readonly<Record<string, number>> | undefined;
+  /**
+   * v1.1 §9.8 — provisioned credentials, present ONLY when this subscriber is
+   * the job's original submitter. Redacted for all other observers (§14).
+   */
+  readonly credentials: readonly Credential[] | undefined;
   readonly subscribedFrom: number;
   readonly replayed: boolean;
   unsubscribe(): Promise<void>;

packages/runtime/src/server-subscribe.ts

@@ -219,6 +219,16 @@ function buildSubscribedPayload(args: {
     subscriberPrincipal !== undefined &&
     job.submitterPrincipal === subscriberPrincipal;
 
+  // §9.6 — current per-currency budget counters, so an observer joining
+  // mid-job sees the live remaining (the cap is derivable from the lease's
+  // `cost.budget` pattern). Empty-map guard avoids an empty `budget: {}`.
+  const budget: Record<string, number> = {};
+  let hasBudget = false;
+  for (const [currency, remaining] of job.budget.entries()) {
+    budget[currency] = remaining;
+    hasBudget = true;
+  }
+
   return {
     job_id: job.jobId,
     current_status: job.state,
@@ -227,6 +237,7 @@ function buildSubscribedPayload(args: {
     ...(job.leaseConstraints === undefined
       ? {}
       : { lease_constraints: job.leaseConstraints }),
+    ...(hasBudget ? { budget } : {}),
     parent_job_id: job.parentJobId ?? null,
     ...(job.traceId === undefined ? {} : { trace_id: job.traceId }),
     subscribed_from: subscribedFrom,

packages/runtime/test/provisioned-credentials.test.ts

@@ -662,4 +662,102 @@ describe("credential confidentiality in job.subscribed (§14)", () => {
     await bobClient.close();
     await server.close();
   });
+
+  it("observer receives budget + lease_constraints on job.subscribed (§7.6)", async () => {
+    const server = new ARCPServer({
+      runtime: TEST_RUNTIME,
+      capabilities: TEST_CAPABILITIES,
+      bearer: new StaticBearerVerifier(
+        new Map([
+          ["tok-alice", { principal: "alice" }],
+          ["tok-bob", { principal: "bob" }],
+        ]),
+      ),
+      // Cross-principal subscription so bob can observe alice's job.
+      jobAuthorizationPolicy: () => true,
+      logger: silentLogger,
+    });
+    server.registerAgent("slow-noop", async () => {
+      await new Promise((r) => setTimeout(r, 200));
+      return null;
+    });
+
+    const [aliceClient, aliceServerSide] = pairMemoryTransports();
+    const [bobClient, bobServerSide] = pairMemoryTransports();
+    server.accept(aliceServerSide);
+    server.accept(bobServerSide);
+    const aliceCollector = new FrameCollector(aliceClient);
+    const bobCollector = new FrameCollector(bobClient);
+
+    // Alice negotiates cost.budget + lease_expires_at so the runtime
+    // initializes/echoes those bounds.
+    await aliceClient.send({
+      arcp: PROTOCOL_VERSION,
+      id: "msg-hello",
+      type: "session.hello",
+      payload: {
+        client: { name: "test-client", version: "0.0.1" },
+        capabilities: {
+          encodings: ["json"],
+          features: ["subscribe", "cost.budget", "lease_expires_at"],
+        },
+        auth: { scheme: "bearer", token: "tok-alice" },
+      },
+    });
+    const aliceSessionId = (
+      await aliceCollector.waitFor((f) => f["type"] === "session.welcome")
+    ).find((f) => f["type"] === "session.welcome")!["session_id"] as string;
+
+    const expiresAt = new Date(Date.now() + 15 * 60_000).toISOString();
+    await aliceClient.send({
+      arcp: PROTOCOL_VERSION,
+      id: "msg-submit-budget",
+      type: "job.submit",
+      session_id: aliceSessionId,
+      payload: {
+        agent: "slow-noop",
+        input: {},
+        lease_request: { "cost.budget": ["USD:5.00"] },
+        lease_constraints: { expires_at: expiresAt },
+      },
+    });
+    const jobId = (
+      (await aliceCollector.waitFor((f) => f["type"] === "job.accepted")).find(
+        (f) => f["type"] === "job.accepted",
+      )!["payload"] as Record<string, unknown>
+    )["job_id"] as string;
+
+    await bobClient.send(helloFrame("tok-bob"));
+    const bobSessionId = (
+      await bobCollector.waitFor((f) => f["type"] === "session.welcome")
+    ).find((f) => f["type"] === "session.welcome")!["session_id"] as string;
+
+    await bobClient.send({
+      arcp: PROTOCOL_VERSION,
+      id: "msg-sub-budget",
+      type: "job.subscribe",
+      session_id: bobSessionId,
+      payload: { job_id: jobId },
+    });
+    const payload = (
+      await bobCollector.waitFor((f) => f["type"] === "job.subscribed")
+    ).find((f) => f["type"] === "job.subscribed")!["payload"] as Record<
+      string,
+      unknown
+    >;
+
+    // Observer (bob) gets the non-secret authority bounds...
+    expect(payload["budget"]).toEqual({ USD: 5 });
+    expect(
+      (payload["lease_constraints"] as Record<string, unknown> | undefined)?.[
+        "expires_at"
+      ],
+    ).toBe(expiresAt);
+    // ...but never credentials.
+    expect(payload["credentials"]).toBeUndefined();
+
+    await aliceClient.close();
+    await bobClient.close();
+    await server.close();
+  });
 });