refactor(agent): make runtime identity explicit

packages/api/session-controller/src/agent.ts

@@ -380,12 +380,14 @@ export class ApiSessionAgentController {
     readonly setup: AgentSetup
   }> {
     const presets = this.ctx.get('agentPresets')
-    if (presets === undefined) return { setup: (agentCtx) => { this.installSelection(agentCtx) } }
+    if (presets === undefined) {
+      return { setup: (_agentCtx, agent) => { this.installSelection(agent) } }
+    }
     const resolvedId = (await presets.resolve(presetId)).id
     return {
       agentPreset: resolvedId,
-      setup: async (agentCtx) => {
-        this.installSelection(agentCtx)
+      setup: async (agentCtx, agent) => {
+        this.installSelection(agent)
         await presets.mount(agentCtx, resolvedId)
       },
     }
@@ -494,9 +496,7 @@ export class ApiSessionAgentController {
     return { provider, model }
   }
 
-  private installSelection(agentCtx: Context): void {
-    const agent = agentCtx.agent
-    if (agent === undefined) throw new Error('api-session: Agent setup has no scoped Agent')
+  private installSelection(agent: Agent): void {
     this.selectionFor(agent)
   }
 

packages/api/session-controller/tests/agent.host.spec.ts

@@ -421,15 +421,12 @@ describe('ApiSession create or adoption', () => {
       .rejects.toBeInstanceOf(ApiSessionCwdConflict)
   })
 
-  it('surfaces directory creation failure and rejects setup without a scoped Agent', async () => {
+  it('surfaces directory creation failure', async () => {
     const { agents } = await harness()
     const parent = mkdtempSync(join(tmpdir(), 'dsh-session-controller-file-'))
     const file = join(parent, 'file')
     writeFileSync(file, 'not a directory')
     await expect(agents.ensureSession(SessionId('mkdir-failure'), join(file, 'child'), false))
       .rejects.toThrow('failed to ensure project directory')
-
-    const composition = await agents.composeAgent(undefined)
-    expect(() => composition.setup(new Context())).toThrow('Agent setup has no scoped Agent')
   })
 })

packages/api/session-controller/tests/session-fork.host.spec.ts

@@ -34,9 +34,9 @@ async function composed(workspaces: readonly Workspace[] = []): Promise<Context>
         ...options.meta === undefined ? {} : { meta: options.meta },
       })
       const agent = {} as Agent
-      const agentCtx = ownerCtx.extend({ agent })
+      const agentCtx = ownerCtx
       Object.assign(agent, { id: session.id, session, status: 'idle', ctx: agentCtx })
-      await options.setup?.(agentCtx)
+      await options.setup?.(agentCtx, agent)
       ctx.agents.register(agent)
       return { agent, dispose: () => Promise.resolve() }
     },

packages/api/session-controller/tests/session-presets.host.spec.ts

@@ -49,9 +49,8 @@ async function harness(presets?: readonly string[]) {
         options.meta === undefined ? {} : { meta: options.meta },
       )
       const agent = stubAgent(session)
-      const agentCtx = ctx.extend({ agent })
-      ;(agent as { ctx?: Context }).ctx = agentCtx
-      await options.setup?.(agentCtx)
+      ;(agent as { ctx?: Context }).ctx = ctx
+      await options.setup?.(ctx, agent)
       const unregister = ctx.agents.register(agent)
       return { agent, dispose: () => { unregister(); return Promise.resolve() } }
     },