feat(ui): configure maxParallelToolCalls for factory-created agents

The acp and stdio-agent plugins only forwarded `model` into their created
agents, so every factory/ACP deployment was pinned to the agent-loop default
parallel cap with no cordis.yml override. Add a `maxParallelToolCalls` config
field (positive-integer validated) to both, threaded through the existing
per-agent options path — symmetric with `model`.

packages/ui/stdio-agent/README.md

@@ -26,6 +26,7 @@ The leaf `cordis.yml` supplies only the **swappable backends** — an LLM adapte
 | Key | Default | Routed to |
 |---|---|---|
 | `model` | (required) | the pre-created `main` agent's model |
+| `maxParallelToolCalls` | (agent-loop default) | positive integer cap on tool calls the `main` agent runs concurrently within one assistant step (`1` is fully serial), routed to `dsh-agent-loop` |
 | `persona` | — | the deployment persona template (may reference `{{model}}`), routed to `dsh-system-prompt` |
 | `toolOrder` | — | explicit model-facing tool order (a name list with one `'<unlisted-tools>'` rest entry; absent — lexicographic; an unregistered name fails each turn at prompt assembly), routed to `dsh-system-prompt` |
 | `persistenceRoot` | `./.sessions` | the JSONL backend's root directory |

packages/ui/stdio-agent/src/index.ts

@@ -65,6 +65,12 @@ export const name = 'stdio-agent'
 export interface Config {
   /** Model name for the `main` agent (must have a registered adapter). */
   model: string
+  /**
+   * Maximum tool calls the `main` agent runs concurrently within one assistant
+   * step (a positive integer; the agent loop defaults it when omitted). `1`
+   * preserves fully serial execution.
+   */
+  maxParallelToolCalls?: number
   /** Deployment persona (the system-prompt plugin's `persona` config). */
   persona?: string
   /** Explicit model-facing tool order (the system-prompt plugin's `toolOrder` config; see dsh-system-prompt). */
@@ -87,6 +93,9 @@ export interface Config {
 
 export const Config: z<Config> = z.object({
   model: z.string().required(),
+  // A positive integer; a bad value (0, negative, fractional) fails config
+  // validation here rather than being silently dropped from cordis.yml.
+  maxParallelToolCalls: z.number().step(1).min(1),
   persona: z.string(),
   // The array default is forced to undefined: ABSENT means "lexicographic
   // order" (the owning dsh-system-prompt schema does the same), while
@@ -116,6 +125,7 @@ export function apply(ctx: Context, config: Config): void {
       id: AgentId('main'),
       model: config.model,
       cwd: process.cwd(),
+      ...config.maxParallelToolCalls !== undefined ? { maxParallelToolCalls: config.maxParallelToolCalls } : {},
       ...config.resumeSessionId !== undefined ? { resumeSessionId: SessionId(config.resumeSessionId) } : {},
     }],
     ...config.skills !== undefined ? { skills: config.skills } : {},

packages/ui/stdio-agent/tests/stdio-agent.spec.ts

@@ -136,6 +136,17 @@ describe('dsh-stdio-agent app', () => {
     await ctx.fiber.dispose()
   })
 
+  it('forwards maxParallelToolCalls onto the pre-created agent when set', async () => {
+    const ctx = await mount({
+      model: 'mock',
+      maxParallelToolCalls: 3,
+      persistenceRoot: '/tmp/dsh-stdio-agent-spec-parallel',
+      skills: await isolatedSkillsConfig(),
+    })
+    expect(ctx.get('agents')?.get(AgentId('main'))?.options.maxParallelToolCalls).toBe(3)
+    await ctx.fiber.dispose()
+  })
+
   it('exposes its name and Config schema', () => {
     expect(stdioAgent.name).toBe('stdio-agent')
     expect(stdioAgent.Config).toBeDefined()