Add optional tools, model, and maxTurns to prompt modules

Why: User overrides of a subagent profile need a place on the shared contract, and empty fields must stay omitted so older modules keep their meaning.
Evidence: go test ./... passed, including the new prompt_module_subagent golden.
Impact: Existing modules serialize the same. Frontend and UI contracts still need a copy of the type.
Refs: feature/agent-harness-p3b
Co-authored-by: Cursor <cursoragent@cursor.com>

conformance_test.go

@@ -60,6 +60,14 @@ func sampleRun() Run {
 	}
 }
 
+func TestGoldenPromptModule(t *testing.T) {
+	golden(t, "prompt_module_subagent", PromptModule{
+		ID: "agent.sub.explore", Layer: LayerAgent, Version: 1,
+		Title: "探索子代理", Body: "只读检索。",
+		Tools: []string{"knowledge_search", "web_search"}, Model: "lightweight", MaxTurns: 8,
+	})
+}
+
 func TestGoldenDomain(t *testing.T) {
 	golden(t, "message", sampleMessage())
 	golden(t, "run", sampleRun())

prompts.go

@@ -26,6 +26,10 @@ type PromptModule struct {
 	BasedOnVersion int            `json:"basedOnVersion,omitempty"` // 用户副本基于的内置版本
 	Drifted     bool             `json:"drifted,omitempty"` // 用户副本落后于当前内置版本（提示用，不阻断）
 	Disabled    bool             `json:"disabled,omitempty"` // 用户停用
+	// 子代理 profile。只对 agent.sub.* 有意义；空字段表示沿用内置。
+	Tools    []string `json:"tools,omitempty"`
+	Model    string   `json:"model,omitempty"`    // lightweight | chat
+	MaxTurns int      `json:"maxTurns,omitempty"`
 }
 
 // PromptTrigger 触发条件；模块命中 = 任一 trigger 命中（再过 RequiresAttachments）。

testdata/golden/prompt_module_subagent.json

@@ -0,0 +1,14 @@
+{
+  "id": "agent.sub.explore",
+  "layer": "agent",
+  "version": 1,
+  "title": "探索子代理",
+  "description": "",
+  "body": "只读检索。",
+  "tools": [
+    "knowledge_search",
+    "web_search"
+  ],
+  "model": "lightweight",
+  "maxTurns": 8
+}

ts/types.ts

@@ -209,6 +209,8 @@ export interface PromptModule {
   body: string; outputContract?: string;
   source?: 'builtin' | 'plugin' | 'user'; owner?: string;
   basedOnVersion?: number; drifted?: boolean; disabled?: boolean;
+  /** 子代理 profile。只对 agent.sub.* 有意义；空字段表示沿用内置。 */
+  tools?: string[]; model?: string; maxTurns?: number;
 }
 
 export interface PromptBlock { moduleId: string; version: number; layer: string; body: string; }