refactor(core): move fork subagent params from execute() to construction time

docs/users/features/memory.md

@@ -2,7 +2,7 @@
 
 Every Qwen Code session starts with a fresh context window. Two mechanisms carry knowledge across sessions so you don't have to re-explain yourself every time:
 
-- **QWEN.md** — instructions *you* write once and Qwen reads every session
+- **QWEN.md** — instructions _you_ write once and Qwen reads every session
 - **Auto-memory** — notes Qwen writes itself based on what it learns from you
 
 ---
@@ -24,9 +24,9 @@ Don't include things Qwen can figure out by reading your code. QWEN.md works bes
 
 ### Where to create QWEN.md
 
-| File | Who it applies to |
-|---|---|
-| `~/.qwen/QWEN.md` | You, across all your projects |
+| File                          | Who it applies to                             |
+| ----------------------------- | --------------------------------------------- |
+| `~/.qwen/QWEN.md`             | You, across all your projects                 |
 | `QWEN.md` in the project root | Your whole team (commit it to source control) |
 
 You can have both. Qwen loads all QWEN.md files it finds when you start a session — your personal one plus any in the project.
@@ -45,6 +45,7 @@ You can point QWEN.md at other files so Qwen reads them too:
 See @README.md for project overview.
 
 # Conventions
+
 - Git workflow: @docs/git-workflow.md
 ```
 
@@ -62,12 +63,12 @@ This is different from QWEN.md: you don't write it, Qwen does.
 
 Qwen looks for four kinds of things worth remembering:
 
-| What | Examples |
-|---|---|
-| **About you** | Your role, background, how you like to work |
-| **Your feedback** | Corrections you made, approaches you confirmed |
-| **Project context** | Ongoing work, decisions, goals not obvious from the code |
-| **External references** | Dashboards, ticket trackers, docs links you mentioned |
+| What                    | Examples                                                 |
+| ----------------------- | -------------------------------------------------------- |
+| **About you**           | Your role, background, how you like to work              |
+| **Your feedback**       | Corrections you made, approaches you confirmed           |
+| **Project context**     | Ongoing work, decisions, goals not obvious from the code |
+| **External references** | Dashboards, ticket trackers, docs links you mentioned    |
 
 Qwen doesn't save everything — only things that would actually be useful next time.
 
@@ -150,6 +151,7 @@ Runs the memory cleanup now instead of waiting for the automatic schedule:
 Open `/memory` to see which files are loaded. If your file isn't listed, Qwen can't see it — make sure it's in the project root or `~/.qwen/`.
 
 Instructions work better when they're specific:
+
 - ✓ `Use 2-space indentation for TypeScript files`
 - ✗ `Format code nicely`
 

packages/cli/src/ui/components/MemoryDialog.tsx

@@ -393,7 +393,9 @@ export function MemoryDialog({ onClose }: MemoryDialogProps) {
                 {index + 1}. {item.label}
               </Text>
               {item.description ? (
-                <Text color={theme.text.secondary}>{`  ${item.description}`}</Text>
+                <Text
+                  color={theme.text.secondary}
+                >{`  ${item.description}`}</Text>
               ) : null}
             </Box>
           );

packages/cli/src/ui/hooks/useReactToolScheduler.ts

@@ -341,7 +341,9 @@ export function mapToDisplay(
   return {
     type: 'tool_group',
     tools: toolDisplays,
-    memoryWriteCount: toolDisplays.filter((t) => t.isMemoryOp === 'write').length || undefined,
-    memoryReadCount: toolDisplays.filter((t) => t.isMemoryOp === 'read').length || undefined,
+    memoryWriteCount:
+      toolDisplays.filter((t) => t.isMemoryOp === 'write').length || undefined,
+    memoryReadCount:
+      toolDisplays.filter((t) => t.isMemoryOp === 'read').length || undefined,
   };
 }

packages/cli/src/utils/commands.test.ts

@@ -71,10 +71,7 @@ describe('parseSlashCommand', () => {
   });
 
   it('should parse a subcommand with arguments', () => {
-    const result = parseSlashCommand(
-      '/config set theme dark',
-      mockCommands,
-    );
+    const result = parseSlashCommand('/config set theme dark', mockCommands);
     expect(result.commandToExecute?.name).toBe('set');
     expect(result.args).toBe('theme dark');
     expect(result.canonicalPath).toEqual(['config', 'set']);

packages/core/src/agents/runtime/agent-core.ts

@@ -110,29 +110,9 @@ export interface CreateChatOptions {
   /**
    * Optional conversation history from a parent session. When provided,
    * this history is prepended to the chat so the agent has prior
-   * conversational context (e.g., from the main session that spawned it).
+   * conversational context (e.g., from AgentInteractive.start()).
    */
   extraHistory?: Content[];
-  /**
-   * When provided, replaces the auto-built generationConfig
-   * (systemInstruction, temperature, etc.) with this exact config.
-   * Used by fork subagents to share the parent conversation's cache
-   * prefix for DashScope prompt caching.
-   */
-  generationConfigOverride?: GenerateContentConfig & {
-    systemInstruction?: string | Content;
-  };
-  /**
-   * When true, skip injecting the env bootstrap messages from
-   * `getInitialChatHistory()`. Set by fork subagents because their
-   * `extraHistory` is the full parent history that already contains
-   * those env messages — re-injecting would duplicate them.
-   *
-   * Other callers (e.g. arena interactive agents) pass an
-   * env-stripped history and DO need fresh env init for their own
-   * working directory, so they must leave this unset.
-   */
-  skipEnvHistory?: boolean;
 }
 
 /**
@@ -243,21 +223,31 @@ export class AgentCore {
     context: ContextState,
     options?: CreateChatOptions,
   ): Promise<GeminiChat | undefined> {
-    if (!this.promptConfig.systemPrompt && !this.promptConfig.initialMessages) {
+    if (
+      !this.promptConfig.systemPrompt &&
+      !this.promptConfig.renderedSystemPrompt &&
+      !this.promptConfig.initialMessages
+    ) {
       throw new Error(
-        'PromptConfig must have either `systemPrompt` or `initialMessages` defined.',
+        'PromptConfig must have `systemPrompt`, `renderedSystemPrompt`, or `initialMessages` defined.',
       );
     }
-    if (this.promptConfig.systemPrompt && this.promptConfig.initialMessages) {
+    if (
+      this.promptConfig.systemPrompt &&
+      this.promptConfig.renderedSystemPrompt
+    ) {
       throw new Error(
-        'PromptConfig cannot have both `systemPrompt` and `initialMessages` defined.',
+        'PromptConfig cannot have both `systemPrompt` and `renderedSystemPrompt` defined.',
       );
     }
 
-    // Skip env bootstrap when the caller (fork) explicitly says its
-    // extraHistory already contains those messages. Other callers that
-    // provide an env-stripped history (e.g. arena) still get fresh env init.
-    const envHistory = options?.skipEnvHistory
+    // When initialMessages is set, the caller owns the full prior history
+    // (including any env bootstrap it wants). Fork relies on this to inherit
+    // the parent conversation verbatim without duplicating env messages.
+    const hasInitialMessages =
+      !!this.promptConfig.initialMessages &&
+      this.promptConfig.initialMessages.length > 0;
+    const envHistory = hasInitialMessages
       ? []
       : await getInitialChatHistory(this.runtimeContext);
 
@@ -267,24 +257,19 @@ export class AgentCore {
       ...(this.promptConfig.initialMessages ?? []),
     ];
 
-    // If an override is provided (fork path), use it directly for cache
-    // sharing. Otherwise, build the config from this agent's promptConfig.
-    // Note: buildChatSystemPrompt is called OUTSIDE the try/catch so template
-    // errors propagate to the caller (not swallowed by reportError).
-    let generationConfig: GenerateContentConfig & {
+    // Build generationConfig. For fork subagents, `renderedSystemPrompt`
+    // carries the parent's exact rendered systemInstruction so the fork
+    // shares a byte-identical cache prefix. Otherwise, template
+    // `systemPrompt` via buildChatSystemPrompt (which may throw — kept
+    // outside the try/catch so template errors surface to the caller).
+    const generationConfig: GenerateContentConfig & {
       systemInstruction?: string | Content;
-    };
-
-    if (options?.generationConfigOverride) {
-      generationConfig = options.generationConfigOverride;
-    } else {
-      const systemInstruction = this.promptConfig.systemPrompt
-        ? this.buildChatSystemPrompt(context, options)
-        : undefined;
-      generationConfig = {
-        temperature: this.modelConfig.temp,
-        topP: this.modelConfig.top_p,
-      };
+    } = {};
+    if (this.promptConfig.renderedSystemPrompt !== undefined) {
+      generationConfig.systemInstruction =
+        this.promptConfig.renderedSystemPrompt;
+    } else if (this.promptConfig.systemPrompt) {
+      const systemInstruction = this.buildChatSystemPrompt(context, options);
       if (systemInstruction) {
         generationConfig.systemInstruction = systemInstruction;
       }
@@ -330,7 +315,10 @@ export class AgentCore {
         (t): t is FunctionDeclaration => typeof t !== 'string',
       );
 
-      if (hasWildcard || asStrings.length === 0) {
+      if (
+        hasWildcard ||
+        (asStrings.length === 0 && onlyInlineDecls.length === 0)
+      ) {
         toolsList.push(
           ...toolRegistry
             .getFunctionDeclarations()

packages/core/src/agents/runtime/agent-headless.test.ts

@@ -231,8 +231,6 @@ describe('subagent.ts', () => {
 
     const defaultModelConfig: ModelConfig = {
       model: 'qwen3-coder-plus',
-      temp: 0.5, // Specific temp to test override
-      top_p: 1,
     };
 
     const defaultRunConfig: RunConfig = {
@@ -439,8 +437,6 @@ describe('subagent.ts', () => {
         // Check Generation Config
         const generationConfig = getGenerationConfigFromMock();
 
-        // Check temperature override
-        expect(generationConfig.temperature).toBe(defaultModelConfig.temp);
         expect(generationConfig.systemInstruction).toContain(
           'Hello Agent, your task is Testing.',
         );
@@ -556,15 +552,20 @@ describe('subagent.ts', () => {
         expect(sysPrompt).not.toContain('---');
       });
 
-      it('should use initialMessages instead of systemPrompt if provided', async () => {
+      it('should replace env history with initialMessages when both initialMessages and systemPrompt are set', async () => {
         const { config } = await createMockConfig();
         vi.mocked(GeminiChat).mockClear();
 
         const initialMessages: Content[] = [
-          { role: 'user', parts: [{ text: 'Hi' }] },
+          { role: 'user', parts: [{ text: 'prior user turn' }] },
+          { role: 'model', parts: [{ text: 'prior model turn' }] },
         ];
-        const promptConfig: PromptConfig = { initialMessages };
+        const promptConfig: PromptConfig = {
+          systemPrompt: 'System ${name}.',
+          initialMessages,
+        };
         const context = new ContextState();
+        context.set('name', 'Agent');
 
         // Model stops immediately
         mockSendMessageStream.mockImplementation(createMockStream(['stop']));
@@ -583,15 +584,44 @@ describe('subagent.ts', () => {
         const generationConfig = getGenerationConfigFromMock();
         const history = callArgs[2];
 
-        expect(generationConfig.systemInstruction).toBeUndefined();
-        expect(history).toEqual([
-          { role: 'user', parts: [{ text: 'Env Context' }] },
-          {
-            role: 'model',
-            parts: [{ text: 'Got it. Thanks for the context!' }],
-          },
-          ...initialMessages,
-        ]);
+        // systemPrompt is templated normally.
+        expect(generationConfig.systemInstruction).toContain('System Agent.');
+        expect(generationConfig.systemInstruction).toContain(
+          'Important Rules:',
+        );
+        // Env bootstrap is skipped; history is exactly initialMessages.
+        expect(history).toEqual(initialMessages);
+      });
+
+      it('should use renderedSystemPrompt verbatim and bypass templating', async () => {
+        const { config } = await createMockConfig();
+        vi.mocked(GeminiChat).mockClear();
+
+        const rendered = 'Verbatim parent system prompt ${name}';
+        const promptConfig: PromptConfig = {
+          renderedSystemPrompt: rendered,
+          initialMessages: [
+            { role: 'user', parts: [{ text: 'hi' }] },
+            { role: 'model', parts: [{ text: 'ok' }] },
+          ],
+        };
+        const context = new ContextState();
+
+        mockSendMessageStream.mockImplementation(createMockStream(['stop']));
+
+        const scope = await AgentHeadless.create(
+          'test-agent',
+          config,
+          promptConfig,
+          defaultModelConfig,
+          defaultRunConfig,
+        );
+
+        await scope.execute(context);
+
+        const generationConfig = getGenerationConfigFromMock();
+        // No ${name} substitution and no non-interactive rules appended.
+        expect(generationConfig.systemInstruction).toBe(rendered);
       });
 
       it('should throw an error if template variables are missing', async () => {
@@ -618,11 +648,11 @@ describe('subagent.ts', () => {
         expect(scope.getTerminateMode()).toBe(AgentTerminateMode.ERROR);
       });
 
-      it('should validate that systemPrompt and initialMessages are mutually exclusive', async () => {
+      it('should validate that systemPrompt and renderedSystemPrompt are mutually exclusive', async () => {
         const { config } = await createMockConfig();
         const promptConfig: PromptConfig = {
           systemPrompt: 'System',
-          initialMessages: [{ role: 'user', parts: [{ text: 'Hi' }] }],
+          renderedSystemPrompt: 'Rendered',
         };
         const context = new ContextState();
 
@@ -635,7 +665,7 @@ describe('subagent.ts', () => {
         );
 
         await expect(agent.execute(context)).rejects.toThrow(
-          'PromptConfig cannot have both `systemPrompt` and `initialMessages` defined.',
+          'PromptConfig cannot have both `systemPrompt` and `renderedSystemPrompt` defined.',
         );
         expect(agent.getTerminateMode()).toBe(AgentTerminateMode.ERROR);
       });

packages/core/src/agents/runtime/agent-headless.ts

@@ -192,21 +192,8 @@ export class AgentHeadless {
   async execute(
     context: ContextState,
     externalSignal?: AbortSignal,
-    options?: {
-      extraHistory?: Array<import('@google/genai').Content>;
-      /** Override generationConfig for cache sharing (fork subagent). */
-      generationConfigOverride?: import('@google/genai').GenerateContentConfig;
-      /** Override tool declarations for cache sharing (fork subagent). */
-      toolsOverride?: Array<import('@google/genai').FunctionDeclaration>;
-      /** Skip env bootstrap injection (fork already inherits parent env). */
-      skipEnvHistory?: boolean;
-    },
   ): Promise<void> {
-    const chat = await this.core.createChat(context, {
-      extraHistory: options?.extraHistory,
-      generationConfigOverride: options?.generationConfigOverride,
-      skipEnvHistory: options?.skipEnvHistory,
-    });
+    const chat = await this.core.createChat(context);
 
     if (!chat) {
       this.terminateMode = AgentTerminateMode.ERROR;
@@ -225,7 +212,7 @@ export class AgentHeadless {
       abortController.abort();
     }
 
-    const toolsList = options?.toolsOverride ?? this.core.prepareTools();
+    const toolsList = this.core.prepareTools();
 
     const initialTaskText = String(
       (context.get('task_prompt') as string) ?? 'Get Started!',