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/acp/README.md

@@ -15,6 +15,7 @@ It is a **client-driver / UI plugin**, the structured analogue of the readline `
 | Key | Default | Meaning |
 |---|---|---|
 | `model` | — | Model name for created agents (must have a registered adapter). |
+| `maxParallelToolCalls` | (agent-loop default) | Positive integer cap on tool calls each created agent runs concurrently within one assistant step; `1` is fully serial. |
 
 (No persona key: `dsh-system-prompt`'s own `persona` config supplies the global default section, so ACP-created agents render it without the bridge carrying prompt text. An agent-scoped same-name section may still shadow that default.)
 

packages/ui/acp/src/index.ts

@@ -248,6 +248,12 @@ function stringArrayContent(
 export interface AcpConfig {
   /** Model name for created agents (must have a registered adapter). */
   model?: string
+  /**
+   * Maximum tool calls each created agent runs concurrently within one assistant
+   * step (a positive integer; the agent loop defaults it when omitted). `1`
+   * preserves fully serial execution.
+   */
+  maxParallelToolCalls?: number
   /**
    * Transport stream override. Production omits this (the plugin wires
    * `process.stdin`/`process.stdout` via `ndJsonStream`). Tests inject an
@@ -260,6 +266,9 @@ export interface AcpConfig {
 
 export const Config: Schema<AcpConfig> = Schema.object({
   model: Schema.string(),
+  // A positive integer; a bad value (0, negative, fractional) fails config
+  // validation here rather than being silently dropped from cordis.yml.
+  maxParallelToolCalls: Schema.number().step(1).min(1),
 })
 
 /**
@@ -1010,12 +1019,13 @@ export function apply(ctx: Context, config: AcpConfig): void {
  * Build per-agent options from the plugin config, omitting absent fields
  * (exactOptionalPropertyTypes: never assign `undefined` to an optional key).
  * Exported for unit coverage of both the present and absent branches.
- * @param config - the plugin config carrying the optional model name.
- * @returns the per-agent options, with `model` present only when configured.
+ * @param config - the plugin config carrying the optional model name and parallel cap.
+ * @returns the per-agent options, with each field present only when configured.
  */
-export function agentOptions(config: AcpConfig): { model?: string } {
+export function agentOptions(config: AcpConfig): { model?: string; maxParallelToolCalls?: number } {
   return {
     ...config.model !== undefined ? { model: config.model } : {},
+    ...config.maxParallelToolCalls !== undefined ? { maxParallelToolCalls: config.maxParallelToolCalls } : {},
   }
 }
 

packages/ui/acp/tests/stream-update.spec.ts

@@ -818,5 +818,7 @@ describe('agentOptions', () => {
   it('includes only the fields present in config', () => {
     expect(agentOptions({})).toEqual({})
     expect(agentOptions({ model: 'm' })).toEqual({ model: 'm' })
+    expect(agentOptions({ maxParallelToolCalls: 3 })).toEqual({ maxParallelToolCalls: 3 })
+    expect(agentOptions({ model: 'm', maxParallelToolCalls: 1 })).toEqual({ model: 'm', maxParallelToolCalls: 1 })
   })
 })