diff --git a/README.md b/README.md
index 7d0a5cd..14867aa 100644
--- a/README.md
+++ b/README.md
@@ -20,7 +20,7 @@ one deployment and one D1 database. No application smart contract is required.
 - The browser uses Authorization Code + PKCE with any compatible OIDC provider.
 - Browser tokens are stored in `localStorage`; Agent Wallet has no login cookie or server session.
 - The Worker validates human access tokens against the configured OIDC issuer/JWKS and keys users by `(iss, sub)`.
-- Realmroot is optional. When used as the authorization server for Agent Wallet's `native` API Resource mode, browser and Agent tokens share one issuer. The Agent token's top-level `sub` is the authorizing user, its RFC 8693 `act` identifies the stable Agent with `sub_profile: ai_agent`, and `cnf.jkt` binds the token to DPoP. The Wallet resolves the issuer's discovered `agent_profile_uri_template` for the Agent's public name and picture.
+- Realmroot is optional. When used as the authorization server for Agent Wallet's `native` API Resource mode, browser and Agent tokens share one issuer. The Agent token's top-level `sub` is the authorizing user, its RFC 8693 `act.iss` and `act.sub` identify the stable Agent, and `cnf.jkt` binds the token to DPoP. The Wallet resolves the issuer's discovered `agent_profile_uri_template` for the Agent's public name and picture.
 - Every Agent payment request requires a fresh DPoP proof. Replayed proofs are rejected.
 - The API publishes RFC 9728 Protected Resource Metadata at
   `/.well-known/oauth-protected-resource/api`. Authentication challenges link
diff --git a/server/auth.ts b/server/auth.ts
index 9674120..41749c4 100644
--- a/server/auth.ts
+++ b/server/auth.ts
@@ -25,6 +25,8 @@ export interface AgentPrincipal {
   scopes: string[]
 }
 
+const realmrootCliClientId = 'realmroot-cli'
+
 function bearer(request: Request, scheme: 'Bearer' | 'DPoP') {
   const value = request.headers.get('authorization')
   const match = value?.match(new RegExp(`^${scheme}\\s+(.+)$`, 'i'))
@@ -82,6 +84,9 @@ export async function authenticateAgent(
     throw agentUnauthorized('Agent access token is invalid.')
   })
   if (protectedHeader.typ !== 'at+jwt') throw agentUnauthorized('Agent access token type is invalid.')
+  if (payload.client_id !== realmrootCliClientId) {
+    throw agentUnauthorized('Agent access token client is invalid.')
+  }
 
   const grantedScopes = scopes(payload)
   if (!grantedScopes.includes(requiredScope)) {
@@ -135,17 +140,10 @@ async function discoverKeySet(issuer: string) {
 }
 
 function resolveRealmrootAgent(payload: JWTPayload, issuer: string) {
-  const agent = payload.act as
-    | {
-        iss?: unknown
-        sub?: unknown
-        sub_profile?: unknown
-      }
-    | undefined
+  const agent = payload.act as { iss?: unknown; sub?: unknown } | undefined
   if (
     agent?.iss !== issuer ||
-    typeof agent.sub !== 'string' ||
-    agent.sub_profile !== 'ai_agent'
+    typeof agent.sub !== 'string'
   ) {
     throw agentUnauthorized('A delegated Realmroot Agent access token is required.')
   }
diff --git a/tests/wallet.test.ts b/tests/wallet.test.ts
index 31b9cd2..592f065 100644
--- a/tests/wallet.test.ts
+++ b/tests/wallet.test.ts
@@ -1581,14 +1581,14 @@ describe('Agent Wallet', () => {
     expect(response.headers.get('www-authenticate')).toContain('invalid_token')
   })
 
-  it('rejects an Agent actor without the ai_agent subject profile', async () => {
+  it('rejects an Agent actor from a different issuer', async () => {
     const token = await humanToken()
     await provisionAndGrant(token)
     const agentToken = await createAgentToken(
       true,
       ['wallet:read', 'wallet:budget:request', 'wallet:x402:pay'],
       audience,
-      'person',
+      'https://untrusted.example/api/auth',
     )
 
     const response = await pay(agentToken, paymentRequired('25000'))
@@ -1600,6 +1600,26 @@ describe('Agent Wallet', () => {
     })
   })
 
+  it('rejects an Agent token issued to a different client', async () => {
+    const token = await humanToken()
+    await provisionAndGrant(token)
+    const agentToken = await createAgentToken(
+      true,
+      ['wallet:read', 'wallet:budget:request', 'wallet:x402:pay'],
+      audience,
+      agentIssuer,
+      'another-client',
+    )
+
+    const response = await pay(agentToken, paymentRequired('25000'))
+
+    expect(response.status).toBe(401)
+    expect(await response.json()).toMatchObject({
+      error: 'unauthorized',
+      message: 'Agent access token client is invalid.',
+    })
+  })
+
   it('does not let another user approve an Agent budget request', async () => {
     const otherToken = await humanToken('user-2')
     const agentToken = await createAgentToken()
@@ -1635,17 +1655,18 @@ async function createAgentToken(
   delegated = true,
   grantedScopes = ['wallet:read', 'wallet:budget:request', 'wallet:x402:pay'],
   tokenAudience = audience,
-  subjectProfile = 'ai_agent',
+  actorIssuer = agentIssuer,
+  clientId = 'realmroot-cli',
 ) {
   const thumbprint = await calculateJwkThumbprint(dpopPublicJwk)
   return new SignJWT({
+    client_id: clientId,
     scope: grantedScopes.join(' '),
     cnf: { jkt: thumbprint },
     act: delegated
       ? {
-          iss: agentIssuer,
+          iss: actorIssuer,
           sub: agentSubject,
-          sub_profile: subjectProfile,
         }
       : undefined,
   })