feat(core): prioritize discussion before formal plan approval (#24423)

evals/plan_mode.eval.ts

@@ -174,7 +174,8 @@ describe('plan_mode', () => {
     params: {
       settings,
     },
-    prompt: 'Create a plan for a new login feature.',
+    prompt:
+      'I agree with the strategy to use a JWT-based login. Create a plan for a new login feature.',
     assert: async (rig, result) => {
       await rig.waitForTelemetryReady();
       const toolLogs = rig.readToolLogs();
@@ -211,7 +212,7 @@ describe('plan_mode', () => {
         'import { sum } from "./mathUtils";\nconsole.log(sum(1, 2));',
     },
     prompt:
-      'I want to refactor our math utilities. Move the `sum` function from `src/mathUtils.ts` to a new file `src/basicMath.ts` and update `src/main.ts` to use the new file. Please create a detailed implementation plan first, then execute it.',
+      'I want to refactor our math utilities. I agree with the strategy to move the `sum` function from `src/mathUtils.ts` to a new file `src/basicMath.ts` and update `src/main.ts`. Please create a detailed implementation plan first, then execute it.',
     assert: async (rig, result) => {
       const enterPlanCalled = await rig.waitForToolCall('enter_plan_mode');
       expect(
@@ -326,4 +327,37 @@ describe('plan_mode', () => {
       assertModelHasOutput(result);
     },
   });
+
+  evalTest('USUALLY_PASSES', {
+    name: 'should not exit plan mode or draft before informal agreement',
+    approvalMode: ApprovalMode.PLAN,
+    params: {
+      settings,
+    },
+    prompt: 'I need to build a new login feature. Please plan it.',
+    assert: async (rig, result) => {
+      await rig.waitForTelemetryReady();
+      const toolLogs = rig.readToolLogs();
+
+      const exitPlanCall = toolLogs.find(
+        (log) => log.toolRequest.name === 'exit_plan_mode',
+      );
+      expect(
+        exitPlanCall,
+        'Should NOT call exit_plan_mode before informal agreement',
+      ).toBeUndefined();
+
+      const planWrite = toolLogs.find(
+        (log) =>
+          log.toolRequest.name === 'write_file' &&
+          log.toolRequest.args.includes('/plans/'),
+      );
+      expect(
+        planWrite,
+        'Should NOT draft the plan file before informal agreement',
+      ).toBeUndefined();
+
+      assertModelHasOutput(result);
+    },
+  });
 });