feat: generate session title from the first recorded prompts

Record up to three sanitized natural-language prompts in session
metadata (skill / plugin activations excluded) and compose the
chat_title input as order-labeled lines truncated to a 1000-char
budget, falling back to lastPrompt for sessions without recorded
prompts.

packages/agent-core-v2/docs/state-manifest.d.ts

@@ -336,6 +336,7 @@ export interface SessionStateSnapshot {
     readonly title?: string;
     readonly isCustomTitle?: boolean;
     readonly lastPrompt?: string;
+    readonly prompts?: readonly string[];
     readonly createdAt: number;
     readonly updatedAt: number;
     readonly archived: boolean;
@@ -1010,7 +1011,7 @@ export interface AgentStateSnapshot {
   'llmRequester.lastConfigLogSignature': string | undefined;
   'llmRequester.mediaDegradedTurns': Set<number>;
   'llmRequester.mediaStrippedTurns': Map<number, /* MediaStripSnapshot — packages/agent-core-v2/src/agent/contextProjector/contextProjector.ts */ {
-    readonly "__@mediaStripSnapshotBrand@2671": undefined;
+    readonly "__@mediaStripSnapshotBrand@2672": undefined;
   }>;
   'llmRequester.turnConfigs': Map<number, /* TurnRequestConfig — packages/agent-core-v2/src/agent/llmRequester/llmRequesterService.ts */ {
     readonly resolved: /* ProfileModelContext — packages/agent-core-v2/src/agent/profile/profile.ts */ {

packages/agent-core-v2/src/agent/rpc/prompt-metadata.ts

@@ -3,12 +3,18 @@
  *
  * Derives title and last-prompt text from native and legacy prompt payloads,
  * persists metadata through `sessionMetadata`, and publishes live updates
- * through `event`. Shared by the native `rpc` prompt path and the v1 legacy
- * prompt adapter so both surfaces keep the same easy-title behavior.
+ * through `event`. Natural-language prompts also append to the metadata's
+ * bounded `prompts` list (the title-generation input); skill / plugin
+ * activations only refresh `lastPrompt`. Shared by the native `rpc` prompt
+ * path and the v1 legacy prompt adapter so both surfaces keep the same
+ * easy-title behavior.
  */
 
 import type { IEventService } from '#/app/event/event';
-import type { ISessionMetadata } from '#/session/sessionMetadata/sessionMetadata';
+import {
+  type ISessionMetadata,
+  SESSION_META_PROMPT_LIMIT,
+} from '#/session/sessionMetadata/sessionMetadata';
 
 import {
   promptMetadataTextFromContentParts,
@@ -58,16 +64,28 @@ export interface PromptMetadataUpdateTarget {
 export async function applyPromptMetadataUpdate(
   target: PromptMetadataUpdateTarget,
   text: string | undefined,
+  recordPrompt = false,
 ): Promise<void> {
   if (text === undefined) return;
   const current = await target.metadata.read();
-  const patch: { lastPrompt: string; title?: string; isCustomTitle?: boolean } = {
+  const patch: {
+    lastPrompt: string;
+    title?: string;
+    isCustomTitle?: boolean;
+    prompts?: readonly string[];
+  } = {
     lastPrompt: text,
   };
   if (!current.isCustomTitle && isUntitled(current.title)) {
     patch.title = titleFromPromptMetadataText(text);
     patch.isCustomTitle = false;
   }
+  // Keep the session's first few natural-language prompts for title
+  // generation. Skill / plugin activations pass recordPrompt=false so command
+  // text never becomes title input.
+  if (recordPrompt && (current.prompts?.length ?? 0) < SESSION_META_PROMPT_LIMIT) {
+    patch.prompts = [...(current.prompts ?? []), text];
+  }
   await target.metadata.update(patch);
   target.eventService.publish({
     type: 'session.meta.updated',

packages/agent-core-v2/src/agent/rpc/rpcService.ts

@@ -95,7 +95,7 @@ export class AgentRPCService implements IAgentRPCService {
         throw error;
       }
     }
-    await this.updatePromptMetadata(promptMetadataTextFromPayload(payload));
+    await this.updatePromptMetadata(promptMetadataTextFromPayload(payload), true);
     const handle = await this.promptService.enqueue({ message: {
       role: 'user',
       content: [...payload.input],
@@ -204,7 +204,10 @@ export class AgentRPCService implements IAgentRPCService {
     await this.updatePromptMetadata(promptMetadataTextFromPluginCommand(payload));
   }
 
-  private async updatePromptMetadata(text: string | undefined): Promise<void> {
+  private async updatePromptMetadata(
+    text: string | undefined,
+    recordPrompt = false,
+  ): Promise<void> {
     await applyPromptMetadataUpdate(
       {
         metadata: this.metadata,
@@ -212,6 +215,7 @@ export class AgentRPCService implements IAgentRPCService {
         sessionId: this.sessionContext.sessionId,
       },
       text,
+      recordPrompt,
     );
   }
 

packages/agent-core-v2/src/session/sessionMetadata/sessionMetadata.ts

@@ -25,12 +25,19 @@ export interface AgentMeta {
 
 export const SESSION_META_VERSION = 2;
 
+/** How many of the session's first natural-language prompts are kept. */
+export const SESSION_META_PROMPT_LIMIT = 3;
+
 export interface SessionMeta {
   readonly id: string;
   readonly version?: number;
   readonly title?: string;
   readonly isCustomTitle?: boolean;
   readonly lastPrompt?: string;
+  /** The session's first sanitized prompt texts (bounded by
+   * `SESSION_META_PROMPT_LIMIT`), recorded for title generation. Absent on
+   * documents written before the recording existed. */
+  readonly prompts?: readonly string[];
   readonly createdAt: number;
   readonly updatedAt: number;
   readonly archived: boolean;

packages/agent-core-v2/src/session/sessionTitle/flag.ts

@@ -19,7 +19,7 @@ export const autoTitleFlag: FlagDefinitionInput = {
   id: AUTO_TITLE_FLAG_ID,
   title: 'Auto session title',
   description:
-    'Generate the session title on demand from the first prompt through the managed chat_title tool. Requires a managed Kimi Code OAuth login.',
+    'Generate the session title on demand from the first prompts through the managed chat_title tool. Requires a managed Kimi Code OAuth login.',
   env: AUTO_TITLE_FLAG_ENV,
   default: false,
   surface: 'both',

packages/agent-core-v2/src/session/sessionTitle/sessionTitle.ts

@@ -2,8 +2,8 @@
  * `sessionTitle` domain (L6) — session title generation contract.
  *
  * Defines the `ISessionTitleService` that (re)generates the session's title
- * on demand from its first prompt through the managed platform's `chat_title`
- * tool. Bound at Session scope — one instance per session.
+ * on demand from its first prompts through the managed platform's
+ * `chat_title` tool. Bound at Session scope — one instance per session.
  */
 
 import { createDecorator, type ServiceIdentifier } from '#/_base/di/instantiation';

packages/agent-core-v2/src/session/sessionTitle/sessionTitleService.ts

@@ -1,9 +1,10 @@
 /**
  * `sessionTitle` domain (L6) — `ISessionTitleService` implementation.
  *
- * Generates the session's title from its already-sanitized first prompt
- * (`sessionMetadata`'s `lastPrompt`, secrets redacted by the prompt-metadata
- * flow) through the managed platform `/tools` `chat_title` endpoint, persists
+ * Generates the session's title from its already-sanitized first prompts
+ * (`sessionMetadata`'s bounded `prompts` list, secrets redacted by the
+ * prompt-metadata flow; `lastPrompt` as the fallback for older documents)
+ * through the managed platform `/tools` `chat_title` endpoint, persists
  * it through `sessionMetadata`, and rebroadcasts `session.meta.updated`.
  * Generation is on demand only: `generateTitle()` is the single entry point
  * (the kap-server route), gated by the `auto-title` experimental flag and a
@@ -32,13 +33,19 @@ import { IHostRequestHeaders } from '#/kosong/model/hostRequestHeaders';
 import { IProviderService } from '#/kosong/provider/provider';
 import { isOAuthCatalogVendor } from '#/kosong/provider/providerDefinition';
 import { ISessionContext } from '#/session/sessionContext/sessionContext';
-import { ISessionMetadata } from '#/session/sessionMetadata/sessionMetadata';
+import {
+  ISessionMetadata,
+  type SessionMeta,
+} from '#/session/sessionMetadata/sessionMetadata';
 
 import { AUTO_TITLE_FLAG_ID } from './flag';
 import { ISessionTitleService } from './sessionTitle';
 
 const MAX_GENERATED_TITLE_LENGTH = 200;
 
+/** Total budget for the composed prompt texts sent to `chat_title`. */
+const MAX_TITLE_INPUT_LENGTH = 1000;
+
 export class SessionTitleService implements ISessionTitleService {
   declare readonly _serviceBrand: undefined;
 
@@ -58,8 +65,9 @@ export class SessionTitleService implements ISessionTitleService {
   async generateTitle(): Promise<string | undefined> {
     if (!this.flags.enabled(AUTO_TITLE_FLAG_ID)) return undefined;
     const current = await this.metadata.read();
-    if (current.lastPrompt === undefined || hasCustomTitle(current)) return undefined;
-    return this.generateAndApply(current.lastPrompt);
+    const input = titleInputFromMeta(current);
+    if (input === undefined || hasCustomTitle(current)) return undefined;
+    return this.generateAndApply(input);
   }
 
   private async generateAndApply(chatContent: string): Promise<string | undefined> {
@@ -103,7 +111,7 @@ export class SessionTitleService implements ISessionTitleService {
     const result = await fetchChatTitle(
       kimiCodeToolsUrl(runtimeAuth.baseUrl),
       token,
-      `user: ${chatContent}`,
+      chatContent,
       {
         headers: {
           ...parseKimiCodeCustomHeaders(),
@@ -143,6 +151,25 @@ function hasCustomTitle(metadata: {
   return metadata.isCustomTitle === true || typeof metadata.customTitle === 'string';
 }
 
+/**
+ * Composes the `chat_title` input from the session's first recorded prompts
+ * (order-labeled), falling back to `lastPrompt` for documents written before
+ * prompt recording existed. Truncated to the total budget, keeping the head.
+ */
+function titleInputFromMeta(meta: SessionMeta): string | undefined {
+  const prompts =
+    meta.prompts !== undefined && meta.prompts.length > 0
+      ? meta.prompts
+      : meta.lastPrompt !== undefined
+        ? [meta.lastPrompt]
+        : undefined;
+  if (prompts === undefined) return undefined;
+  return prompts
+    .map((prompt, index) => `user ${index + 1}: ${prompt}`)
+    .join('\n')
+    .slice(0, MAX_TITLE_INPUT_LENGTH);
+}
+
 registerScopedService(
   LifecycleScope.Session,
   ISessionTitleService,

packages/agent-core-v2/test/agent/rpc/prompt-metadata.test.ts

@@ -7,12 +7,24 @@
  *   - an inline image-compression caption (harness metadata placed next to
  *     the image by prompt ingestion) never leaks into titles/lastPrompt,
  *     whether it is a standalone text part or merged into the user's text
+ *   - natural-language prompts append to the bounded `prompts` metadata list
+ *     (the title-generation input) while skill / plugin activations do not
  */
 
 import { describe, expect, it } from 'vitest';
 
-import { promptMetadataTextFromPayload } from '#/agent/rpc/prompt-metadata';
+import {
+  applyPromptMetadataUpdate,
+  promptMetadataTextFromPayload,
+  type PromptMetadataUpdateTarget,
+} from '#/agent/rpc/prompt-metadata';
 import { buildImageCompressionCaption } from '#/agent/media/image-compress';
+import type { IEventService } from '#/app/event/event';
+import {
+  type ISessionMetadata,
+  type SessionMeta,
+  type SessionMetaPatch,
+} from '#/session/sessionMetadata/sessionMetadata';
 
 const CAPTION = buildImageCompressionCaption({
   original: { width: 3264, height: 666, byteLength: 344 * 1024, mimeType: 'image/png' },
@@ -53,3 +65,56 @@ describe('promptMetadataTextFromPayload', () => {
     expect(text).not.toContain('Image compressed');
   });
 });
+
+describe('applyPromptMetadataUpdate', () => {
+  function createTarget(initial: Partial<SessionMeta> = {}) {
+    let meta: SessionMeta = {
+      id: 'sess-1',
+      createdAt: 0,
+      updatedAt: 0,
+      archived: false,
+      ...initial,
+    };
+    const target: PromptMetadataUpdateTarget = {
+      metadata: {
+        read: () => Promise.resolve(meta),
+        update: (patch: SessionMetaPatch) => {
+          meta = { ...meta, ...patch };
+          return Promise.resolve();
+        },
+      } as unknown as ISessionMetadata,
+      eventService: { publish: () => undefined } as unknown as IEventService,
+      sessionId: 'sess-1',
+    };
+    return { target, readMeta: () => meta };
+  }
+
+  it('records natural-language prompts into the bounded prompts list', async () => {
+    const { target, readMeta } = createTarget();
+
+    await applyPromptMetadataUpdate(target, '第一条', true);
+    await applyPromptMetadataUpdate(target, '第二条', true);
+
+    expect(readMeta().prompts).toEqual(['第一条', '第二条']);
+    expect(readMeta().lastPrompt).toBe('第二条');
+    expect(readMeta().title).toBe('第一条');
+  });
+
+  it('does not record skill / plugin activations', async () => {
+    const { target, readMeta } = createTarget();
+
+    await applyPromptMetadataUpdate(target, '/compact');
+
+    expect(readMeta().lastPrompt).toBe('/compact');
+    expect(readMeta().prompts).toBeUndefined();
+  });
+
+  it('stops recording once the prompt limit is reached', async () => {
+    const { target, readMeta } = createTarget({ prompts: ['一', '二', '三'] });
+
+    await applyPromptMetadataUpdate(target, '第四条', true);
+
+    expect(readMeta().prompts).toEqual(['一', '二', '三']);
+    expect(readMeta().lastPrompt).toBe('第四条');
+  });
+});

packages/agent-core-v2/test/session/sessionTitle/sessionTitleService.test.ts

@@ -184,7 +184,7 @@ describe('SessionTitleService', () => {
   });
 
   it('replaces the easy title with the generated one', async () => {
-    await metadata.update({ lastPrompt: '帮我看一下这个 Go 的 nil pointer 报错' });
+    await metadata.update({ prompts: ['帮我看一下这个 Go 的 nil pointer 报错'] });
 
     const title = await ix.get(ISessionTitleService).generateTitle();
 
@@ -195,7 +195,7 @@ describe('SessionTitleService', () => {
     const [, init] = fetchMock.mock.calls[0]!;
     expect(JSON.parse(init?.body as string)).toEqual({
       method: 'chat_title',
-      params: { chat_content: 'user: 帮我看一下这个 Go 的 nil pointer 报错' },
+      params: { chat_content: 'user 1: 帮我看一下这个 Go 的 nil pointer 报错' },
     });
     expect(new Headers(init?.headers as Record<string, string>).get('authorization')).toBe(
       'Bearer test-token',
@@ -209,6 +209,45 @@ describe('SessionTitleService', () => {
     expect(rebroadcast).toBeDefined();
   });
 
+  it('composes the title input from the recorded prompts in order', async () => {
+    await metadata.update({
+      prompts: ['先帮我搭一个 Vite 项目', '加上路由', '现在配一下 ESLint'],
+    });
+
+    await ix.get(ISessionTitleService).generateTitle();
+
+    const [, init] = fetchMock.mock.calls[0]!;
+    expect(JSON.parse(init?.body as string)).toEqual({
+      method: 'chat_title',
+      params: {
+        chat_content: 'user 1: 先帮我搭一个 Vite 项目\nuser 2: 加上路由\nuser 3: 现在配一下 ESLint',
+      },
+    });
+  });
+
+  it('truncates the composed title input to the total budget, keeping the head', async () => {
+    await metadata.update({ prompts: ['很长的输入'.repeat(400), '第二条'] });
+
+    await ix.get(ISessionTitleService).generateTitle();
+
+    const [, init] = fetchMock.mock.calls[0]!;
+    const body = JSON.parse(init?.body as string) as { params: { chat_content: string } };
+    expect(body.params.chat_content.startsWith('user 1: 很长的输入')).toBe(true);
+    expect(body.params.chat_content).toHaveLength(1000);
+  });
+
+  it('falls back to lastPrompt for sessions without recorded prompts', async () => {
+    await metadata.update({ lastPrompt: '帮我看一下这个 Go 的 nil pointer 报错' });
+
+    await ix.get(ISessionTitleService).generateTitle();
+
+    const [, init] = fetchMock.mock.calls[0]!;
+    expect(JSON.parse(init?.body as string)).toEqual({
+      method: 'chat_title',
+      params: { chat_content: 'user 1: 帮我看一下这个 Go 的 nil pointer 报错' },
+    });
+  });
+
   it('does nothing without a managed OAuth provider', async () => {
     delete providers['managed:kimi-code'];
     await metadata.update({ lastPrompt: 'hello' });