fix(kap-server): apply plan mode from prompt submissions

.changeset/fix-web-first-prompt-plan-mode.md

@@ -0,0 +1,5 @@
+---
+"@moonshot-ai/kimi-code": patch
+---
+
+Fix Plan Mode not taking effect on the first prompt of a new Web session.

packages/kap-server/src/routes/prompts.ts

@@ -11,6 +11,7 @@ import {
   IBootstrapService,
   IAgentLifecycleService,
   IAgentPermissionModeService,
+  IAgentPlanService,
   IAgentProfileService,
   IAgentToolPolicyService,
   IAgentPromptService,
@@ -119,6 +120,7 @@ async function resolvePromptFromSession(session: ISessionScopeHandle, agentId?:
     profile: agent.accessor.get(IAgentProfileService),
     toolPolicy: agent.accessor.get(IAgentToolPolicyService),
     permissionMode: agent.accessor.get(IAgentPermissionModeService),
+    plan: agent.accessor.get(IAgentPlanService),
   };
 }
 
@@ -257,6 +259,13 @@ export function registerPromptsRoutes(app: PromptRouteHost, core: Scope): void {
         if (req.body.thinking !== undefined && !thinkingConsumed)
           resolved.profile.setThinking(req.body.thinking);
         if (req.body.permission_mode !== undefined) resolved.permissionMode.setMode(req.body.permission_mode);
+        if (req.body.plan_mode !== undefined) {
+          const active = (await resolved.plan.status()) !== null;
+          if (active !== req.body.plan_mode) {
+            if (req.body.plan_mode) await resolved.plan.enter();
+            else resolved.plan.exit();
+          }
+        }
         if (req.body.disabled_tools !== undefined) {
           // A session denylist before bind throws `profile.not_bound` — map it
           // onto 40001 like the profile-selection errors above.

packages/kap-server/test/prompts.test.ts

@@ -215,6 +215,48 @@ describe('server-v2 /api/v1 prompts', () => {
     expect(Array.isArray(list.body.data.queued)).toBe(true);
   });
 
+  it('enters plan mode when the first prompt requests it', async () => {
+    const id = await createSession(home as string);
+
+    const submitted = await call<PromptItemWire>('POST', `/api/v1/sessions/${id}/prompts`, {
+      model: 'stub',
+      plan_mode: true,
+      content: [{ type: 'text', text: 'investigate the bug' }],
+    });
+    expect(submitted.body.code).toBe(0);
+
+    const status = await call<{ plan_mode: boolean }>(
+      'GET',
+      `/api/v1/sessions/${id}/status`,
+    );
+    expect(status.body.code).toBe(0);
+    expect(status.body.data.plan_mode).toBe(true);
+  });
+
+  it('exits plan mode when a prompt disables it', async () => {
+    const id = await createSession(home as string);
+    await createMainAgent(id);
+
+    const profile = await call<unknown>('POST', `/api/v1/sessions/${id}/profile`, {
+      agent_config: { plan_mode: true },
+    });
+    expect(profile.body.code).toBe(0);
+
+    const submitted = await call<PromptItemWire>('POST', `/api/v1/sessions/${id}/prompts`, {
+      model: 'stub',
+      plan_mode: false,
+      content: [{ type: 'text', text: 'implement the fix' }],
+    });
+    expect(submitted.body.code).toBe(0);
+
+    const status = await call<{ plan_mode: boolean }>(
+      'GET',
+      `/api/v1/sessions/${id}/status`,
+    );
+    expect(status.body.code).toBe(0);
+    expect(status.body.data.plan_mode).toBe(false);
+  });
+
   it('rejects a stale file reference without creating the agent or mutating the model', async () => {
     const id = await createSession(home as string);
     const session = getLiveSessionById(server!.core.accessor, id);