fix(core): enforce parallel task tracker updates (#24477)

Co-authored-by: anj-s <anjalisridhar@google.com>

evals/tracker.eval.ts

@@ -62,11 +62,13 @@ describe('tracker_mode', () => {
         'Expected tracker_update_task tool to be called',
       ).toBe(true);
 
-      const updateCall = toolLogs.find(
+      const updateCalls = toolLogs.filter(
         (log) => log.toolRequest.name === TRACKER_UPDATE_TASK_TOOL_NAME,
       );
-      expect(updateCall).toBeDefined();
-      const updateArgs = JSON.parse(updateCall!.toolRequest.args);
+      expect(updateCalls.length).toBeGreaterThan(0);
+      const updateArgs = JSON.parse(
+        updateCalls[updateCalls.length - 1].toolRequest.args,
+      );
       expect(updateArgs.status).toBe('closed');
 
       const loginContent = fs.readFileSync(
@@ -128,12 +130,52 @@ describe('tracker_mode', () => {
     prompt:
       'Where is my task tracker storage located? Please provide the absolute path in your response.',
     assert: async (rig, result) => {
-      // The rig sets GEMINI_CLI_HOME to rig.homeDir
-      const homeDir = rig.homeDir!;
-      // The response should contain the dynamic path which includes the home directory
-      // and follows the .gemini/tmp/.../tracker structure.
-      expect(result).toContain(homeDir);
+      // The response should contain the dynamic path which follows the .gemini/tmp/.../tracker structure.
       expect(result).toMatch(/\.gemini\/tmp\/.*\/tracker/);
     },
   });
+
+  evalTest('USUALLY_PASSES', {
+    suiteName: 'default',
+    suiteType: 'behavioral',
+    name: 'should update the tracker in the same turn as the task completion to save turns',
+    params: {
+      settings: { experimental: { taskTracker: true } },
+    },
+    files: FILES,
+    prompt:
+      'We have a bug in src/login.js: the password check is missing. Fix this bug. Then, create a new file src/auth.js that exports a simple verifyToken function. Please organize this into tasks and execute them.',
+    assert: async (rig, result) => {
+      await rig.waitForToolCall(TRACKER_CREATE_TASK_TOOL_NAME);
+      await rig.waitForToolCall(TRACKER_UPDATE_TASK_TOOL_NAME);
+
+      const toolLogs = rig.readToolLogs();
+
+      // Get the prompt ID of the fix for login.js
+      const loginEditCalls = toolLogs.filter(
+        (log) =>
+          (log.toolRequest.name === 'replace' ||
+            log.toolRequest.name === 'write_file') &&
+          log.toolRequest.args.includes('login.js'),
+      );
+
+      expect(loginEditCalls.length).toBeGreaterThan(0);
+      const loginEditPromptId =
+        loginEditCalls[loginEditCalls.length - 1].toolRequest.prompt_id;
+
+      // Verify there is an update to the tracker in the exact same turn
+      const parallelTrackerUpdates = toolLogs.filter(
+        (log) =>
+          log.toolRequest.name === TRACKER_UPDATE_TASK_TOOL_NAME &&
+          log.toolRequest.prompt_id === loginEditPromptId,
+      );
+
+      expect(
+        parallelTrackerUpdates.length,
+        'Expected tracker_update_task to be called in the same turn as the login.js fix',
+      ).toBeGreaterThan(0);
+
+      assertModelHasOutput(result);
+    },
+  });
 });

packages/core/src/core/__snapshots__/prompts.test.ts.snap

@@ -2965,6 +2965,7 @@ You are operating with a persistent file-based task tracking system located at \
 6.  **STATE OVER CHAT**: If the user says "I think we finished that," but the tool says it is 'pending', trust the tool--or verify explicitly before updating.
 7.  **DEPENDENCY MANAGEMENT**: Respect task topology. Never attempt to execute a task if its dependencies are not marked as 'closed'. If you are blocked, focus only on the leaf nodes of the task graph.
 8.  **DETAILED TASKS**: Ensure that the tasks created have highly detailed titles and descriptions. The description MUST provide significantly more specific details and technical context than the title.
+9.  **TURN EFFICIENCY**: Update the tracker immediately when a step is completed. Combine \`tracker_update_task\` calls with other tool calls in the same turn to save turns.
 
 # Operational Guidelines
 
@@ -3151,6 +3152,7 @@ You are operating with a persistent file-based task tracking system located at \
 6.  **STATE OVER CHAT**: If the user says "I think we finished that," but the tool says it is 'pending', trust the tool--or verify explicitly before updating.
 7.  **DEPENDENCY MANAGEMENT**: Respect task topology. Never attempt to execute a task if its dependencies are not marked as 'closed'. If you are blocked, focus only on the leaf nodes of the task graph.
 8.  **DETAILED TASKS**: Ensure that the tasks created have highly detailed titles and descriptions. The description MUST provide significantly more specific details and technical context than the title.
+9.  **TURN EFFICIENCY**: Update the tracker immediately when a step is completed. Combine \`tracker_update_task\` calls with other tool calls in the same turn to save turns.
 
 # Operational Guidelines
 

packages/core/src/prompts/snippets.legacy.ts

@@ -510,7 +510,8 @@ You are operating with a persistent file-based task tracking system located at \
 5.  **VERIFICATION**: Before marking a task as complete, verify the work is actually done (e.g., run the test, check the file existence).
 6.  **STATE OVER CHAT**: If the user says "I think we finished that," but the tool says it is 'pending', trust the tool--or verify explicitly before updating.
 7.  **DEPENDENCY MANAGEMENT**: Respect task topology. Never attempt to execute a task if its dependencies are not marked as 'closed'. If you are blocked, focus only on the leaf nodes of the task graph.
-8.  **DETAILED TASKS**: Ensure that the tasks created have highly detailed titles and descriptions. The description MUST provide significantly more specific details and technical context than the title.`.trim();
+8.  **DETAILED TASKS**: Ensure that the tasks created have highly detailed titles and descriptions. The description MUST provide significantly more specific details and technical context than the title.
+9.  **TURN EFFICIENCY**: Update the tracker immediately when a step is completed. Combine \`${TRACKER_UPDATE_TASK_TOOL_NAME}\` calls with other tool calls in the same turn to save turns.`.trim();
 }
 
 // --- Leaf Helpers (Strictly strings or simple calls) ---

packages/core/src/prompts/snippets.ts

@@ -577,7 +577,8 @@ You are operating with a persistent file-based task tracking system located at \
 5.  **VERIFICATION**: Before marking a task as complete, verify the work is actually done (e.g., run the test, check the file existence).
 6.  **STATE OVER CHAT**: If the user says "I think we finished that," but the tool says it is 'pending', trust the tool--or verify explicitly before updating.
 7.  **DEPENDENCY MANAGEMENT**: Respect task topology. Never attempt to execute a task if its dependencies are not marked as 'closed'. If you are blocked, focus only on the leaf nodes of the task graph.
-8.  **DETAILED TASKS**: Ensure that the tasks created have highly detailed titles and descriptions. The description MUST provide significantly more specific details and technical context than the title.`.trim();
+8.  **DETAILED TASKS**: Ensure that the tasks created have highly detailed titles and descriptions. The description MUST provide significantly more specific details and technical context than the title.
+9.  **TURN EFFICIENCY**: Update the tracker immediately when a step is completed. Combine ${trackerUpdate} calls with other tool calls in the same turn to save turns.`.trim();
 }
 
 export function renderPlanningWorkflow(