refactor(tasks): simplify admission configuration

packages/examples/acp-demo/tests/acp-agent.spec.ts

@@ -186,12 +186,24 @@ describe('dsh-acp-demo composition', () => {
     const ctx = await mount({
       provider: 'mock',
       model: 'mock',
-      tasks: { maxConcurrentTasksPerOwner: 2 },
+      tasks: { maxConcurrentTasksPerOwner: 1 },
       skills: await isolatedSkillsConfig(),
       workspaceContext: false,
     })
-    expect((ctx.tasks as unknown as { config: { maxConcurrentTasksPerOwner: number } })
-      .config.maxConcurrentTasksPerOwner).toBe(2)
+    let settle!: (outcome: { status: 'killed' }) => void
+    ctx.tasks.start({
+      kind: 'bash',
+      label: 'hold configured slot',
+      run: () => ({
+        cancel: () => { settle({ status: 'killed' }) },
+        done: new Promise((resolve) => { settle = resolve }),
+      }),
+    })
+    expect(() => ctx.tasks.start({
+      kind: 'bash',
+      label: 'blocked configured task',
+      run: () => ({ cancel: () => {}, done: Promise.resolve({ status: 'completed' }) }),
+    })).toThrow('(limit: 1)')
     await ctx.fiber.dispose()
   })