fix(agent-core-v2): refresh system prompt after compaction

packages/agent-core-v2/docs/di-scope-domains.puml

@@ -307,6 +307,7 @@ fullCompaction --> llmRequester #34495E
 fullCompaction --> profile #34495E
 fullCompaction --> toolRegistry #34495E
 fullCompaction --> telemetry #34495E
+fullCompaction --> log #34495E
 fullCompaction --> wireRecord #34495E
 fullCompaction --> turn #34495E
 fullCompaction --> loop #34495E

packages/agent-core-v2/src/agent/fullCompaction/fullCompactionService.ts

@@ -1,6 +1,7 @@
 import { Disposable } from "#/_base/di/lifecycle";
 import { InstantiationType } from '#/_base/di/extensions';
 import { LifecycleScope, registerScopedService } from '#/_base/di/scope';
+import { ILogService } from '#/_base/log/log';
 import { renderPrompt } from "#/_base/utils/render-prompt";
 import {
   estimateTokens,
@@ -132,6 +133,7 @@ export class AgentFullCompactionService extends Disposable implements IAgentFull
     @IAgentWireService private readonly wire: IWireService,
     @IEventBus private readonly eventBus: IEventBus,
     @IAgentTurnService private readonly turn: IAgentTurnService,
+    @ILogService private readonly log: ILogService,
     @IAgentLoopService loopService: IAgentLoopService,
   ) {
     super();
@@ -421,6 +423,11 @@ export class AgentFullCompactionService extends Disposable implements IAgentFull
     try {
       const result = await this.compactionRound(active, data);
       if (this._compacting !== active) throw compactionCancelledReason(active);
+      try {
+        await this.profile.refreshSystemPrompt();
+      } catch (error) {
+        this.log.error('failed to refresh system prompt after compaction', { error });
+      }
       this.lastCompactedTokenCount = result.tokensAfter;
       if (!this.markCompleted(active)) {
         throw compactionCancelledReason(active);

packages/agent-core-v2/src/agent/profile/profile.ts

@@ -153,6 +153,11 @@ export interface IAgentProfileService {
    * {@link getAgentsMdWarning} / `getSessionWarnings`.
    */
   applyProfile(profile: ResolvedAgentProfile, options?: ApplyProfileOptions): Promise<void>;
+  /**
+   * Re-render the active profile's system prompt from freshly gathered runtime
+   * context without changing the active tool set.
+   */
+  refreshSystemPrompt(): Promise<void>;
   /**
    * The AGENTS.md size warning produced by the most recent {@link applyProfile},
    * if the combined AGENTS.md content exceeded the recommended soft budget.

packages/agent-core-v2/src/agent/profile/profileService.ts

@@ -110,6 +110,8 @@ export class AgentProfileService implements IAgentProfileService {
     );
   }
 
+  private activeProfile: ResolvedAgentProfile | undefined;
+
   constructor(
     @IAgentWireService private readonly wire: IWireService,
     @IEventBus private readonly eventBus: IEventBus,
@@ -137,6 +139,12 @@ export class AgentProfileService implements IAgentProfileService {
 
   update(changed: ProfileUpdateData): void {
     const { activeToolNames, ...configChanged } = changed;
+    if (
+      changed.profileName !== undefined &&
+      this.activeProfile?.name !== changed.profileName
+    ) {
+      this.activeProfile = undefined;
+    }
     if (Object.keys(configChanged).length > 0) {
       this.wire.dispatch(configUpdate(this.resolveConfigPayload(configChanged)));
       this.afterConfigDispatch(configChanged);
@@ -157,8 +165,8 @@ export class AgentProfileService implements IAgentProfileService {
 
     const context = await this.buildSystemPromptContext(input.cwd);
     const systemPrompt = profile.systemPrompt(context);
-    const { agentsMdWarning } = context;
-    this.agentsMdWarning = agentsMdWarning;
+    this.activeProfile = profile;
+    this.cacheAgentsMdWarning(context);
 
     const thinkingLevel = resolveThinkingEffort(
       input.thinking,
@@ -175,13 +183,7 @@ export class AgentProfileService implements IAgentProfileService {
     this.wire.dispatch(configUpdate({ modelAlias: input.model, thinkingEffort: thinkingLevel }));
     this.afterConfigDispatch({ modelAlias: input.model, thinkingLevel });
 
-    if (agentsMdWarning !== undefined) {
-      this.eventBus.publish({
-        type: 'warning',
-        message: agentsMdWarning,
-        code: 'agents-md-oversized',
-      });
-    }
+    this.publishAgentsMdWarning();
   }
 
   async setModel(alias: string): Promise<ProfileSetModelResult> {
@@ -213,6 +215,7 @@ export class AgentProfileService implements IAgentProfileService {
   }
 
   useProfile(profile: ResolvedAgentProfile, context: SystemPromptContext): void {
+    this.activeProfile = profile;
     this.update({
       profileName: profile.name,
       systemPrompt: profile.systemPrompt(context),
@@ -221,24 +224,24 @@ export class AgentProfileService implements IAgentProfileService {
   }
 
   async applyProfile(profile: ResolvedAgentProfile, options?: ApplyProfileOptions): Promise<void> {
-    const context = await prepareSystemPromptContext(
-      { fs: this.fs, homeDir: this.env.homeDir },
-      this.sessionContext.cwd,
-      this.bootstrap.homeDir,
-      {
-        additionalDirs: options?.additionalDirs ?? this.workspace.additionalDirs,
-      },
-    );
+    const context = await this.buildSystemPromptContext(undefined, options);
     this.useProfile(profile, context);
-    const { agentsMdWarning } = context;
-    this.agentsMdWarning = agentsMdWarning;
-    if (agentsMdWarning !== undefined) {
-      this.eventBus.publish({
-        type: 'warning',
-        message: agentsMdWarning,
-        code: 'agents-md-oversized',
-      });
-    }
+    this.cacheAgentsMdWarning(context);
+    this.publishAgentsMdWarning();
+  }
+
+  async refreshSystemPrompt(): Promise<void> {
+    const profile = this.resolveActiveProfile();
+    if (profile === undefined) return;
+
+    const context = await this.buildSystemPromptContext(this.cwd);
+    this.activeProfile = profile;
+    this.update({
+      profileName: profile.name,
+      systemPrompt: profile.systemPrompt(context),
+    });
+    this.cacheAgentsMdWarning(context);
+    this.publishAgentsMdWarning();
   }
 
   getAgentsMdWarning(): string | undefined {
@@ -490,13 +493,37 @@ export class AgentProfileService implements IAgentProfileService {
     }
   }
 
-  private async buildSystemPromptContext(cwd?: string): Promise<SystemPromptContext> {
+  private resolveActiveProfile(): ResolvedAgentProfile | undefined {
+    if (this.activeProfile !== undefined) return this.activeProfile;
+    const profileName = this.profileName;
+    if (profileName === undefined) return undefined;
+    return this.catalog.get(profileName);
+  }
+
+  private cacheAgentsMdWarning(context: Pick<SystemPromptContext, 'agentsMdWarning'>): void {
+    this.agentsMdWarning = context.agentsMdWarning;
+  }
+
+  private publishAgentsMdWarning(): void {
+    const warning = this.agentsMdWarning;
+    if (warning === undefined) return;
+    this.eventBus.publish({
+      type: 'warning',
+      message: warning,
+      code: 'agents-md-oversized',
+    });
+  }
+
+  private async buildSystemPromptContext(
+    cwd?: string,
+    options?: ApplyProfileOptions,
+  ): Promise<SystemPromptContext> {
     const effectiveCwd = cwd ?? this.sessionContext.cwd;
     const base = await prepareSystemPromptContext(
       { fs: this.fs, homeDir: this.env.homeDir },
       effectiveCwd,
       this.bootstrap.homeDir,
-      { additionalDirs: this.workspace.additionalDirs },
+      { additionalDirs: options?.additionalDirs ?? this.workspace.additionalDirs },
     );
     const skills = await this.resolveSkillListing();
     return {

packages/agent-core-v2/test/fullCompaction/full.test.ts

@@ -1,4 +1,4 @@
-import { existsSync, mkdtempSync, readFileSync, writeFileSync } from 'node:fs';
+import { existsSync, mkdtempSync, readFileSync, rmSync, writeFileSync } from 'node:fs';
 import { tmpdir } from 'node:os';
 import { join } from 'pathe';
 
@@ -19,14 +19,16 @@ import { MASTER_ENV } from '#/app/flag/flagService';
 import { estimateTokensForMessages } from '#/_base/utils/tokens';
 import { recordingTelemetry, type TelemetryRecord } from '../telemetry/stubs';
 import type { TestAgentContext, TestAgentOptions, TestAgentServiceOverride } from '../harness';
-import { appServices, createCommandRunner, execEnvServices, sessionServices, testAgent } from '../harness';
+import { appServices, createCommandRunner, execEnvServices, hostEnvironmentServices, sessionServices, testAgent } from '../harness';
 import {
   IAgentFullCompactionService,
   IOAuthService,
   IAgentProfileService,
   ISessionTodoService,
+  type ResolvedAgentProfile,
 } from '#/index';
 import { IAgentTurnService } from '#/agent/turn/turn';
+import { HostFileSystem } from '#/os/backends/node-local/hostFsService';
 
 type GenerateFn = NonNullable<TestAgentOptions['generate']>;
 
@@ -53,6 +55,19 @@ const SNAPSHOT_VISIBLE_TOOLS = [
   'EnterPlanMode',
   'ExitPlanMode',
 ] as const;
+const EXACT_COMPACTION_REFRESH_PROFILE: ResolvedAgentProfile = {
+  name: 'exact-compaction-refresh',
+  systemPrompt: (context) =>
+    [
+      `cwd:${context.cwd ?? ''}`,
+      `os:${context.osKind ?? ''}`,
+      `shell:${context.shellName ?? ''}:${context.shellPath ?? ''}`,
+      `agents:${context.agentsMd ?? ''}`,
+      `ls:${context.cwdListing ?? ''}`,
+      `extra:${context.additionalDirsInfo ?? ''}`,
+    ].join('\n'),
+  tools: ['Read', 'Write', 'Skill'],
+};
 
 describe('FullCompaction', () => {
   it('keeps an oversized trailing user message as recent', () => {
@@ -278,6 +293,46 @@ describe('FullCompaction', () => {
     await ctx.expectResumeMatches();
   });
 
+  it('refreshes the active profile system prompt after compaction without resetting active tools', async () => {
+    const homeDir = mkdtempSync(join(tmpdir(), 'kimi-compact-refresh-home-'));
+    const workDir = mkdtempSync(join(tmpdir(), 'kimi-compact-refresh-work-'));
+    try {
+      writeFileSync(join(workDir, 'AGENTS.md'), 'old project instructions', 'utf-8');
+      const ctx = testAgent(
+        execEnvServices({ hostFs: new HostFileSystem() }),
+        hostEnvironmentServices(homeDir),
+        { autoConfigure: false, cwd: workDir },
+      );
+      ctx.configureRuntimeModel(CATALOGUED_PROVIDER, CATALOGUED_MODEL_CAPABILITIES);
+      const profile = ctx.get(IAgentProfileService);
+      await profile.applyProfile(EXACT_COMPACTION_REFRESH_PROFILE);
+      profile.update({ activeToolNames: ['Read'] });
+
+      expect(profile.data().systemPrompt).toBe(
+        exactCompactionRefreshPrompt(workDir, 'old project instructions'),
+      );
+
+      const refreshSpy = vi.spyOn(profile, 'refreshSystemPrompt');
+      writeFileSync(join(workDir, 'AGENTS.md'), 'new project instructions', 'utf-8');
+      ctx.appendExchange(1, 'old user one', 'old assistant one', 20);
+      ctx.appendExchange(2, 'recent user two', 'recent assistant two', 80);
+      const completed = ctx.once('compaction.completed');
+
+      ctx.mockNextResponse({ type: 'text', text: 'Compacted summary.' });
+      await ctx.rpc.beginCompaction({});
+      await completed;
+
+      expect(refreshSpy).toHaveBeenCalledTimes(1);
+      expect(profile.data().systemPrompt).toBe(
+        exactCompactionRefreshPrompt(workDir, 'new project instructions'),
+      );
+      expect(profile.getActiveToolNames()).toEqual(['Read']);
+    } finally {
+      rmSync(homeDir, { recursive: true, force: true });
+      rmSync(workDir, { recursive: true, force: true });
+    }
+  });
+
   it('rejects a manual compaction while a turn is active', async () => {
     const ctx = testAgent(execEnvServices({ processRunner: createCommandRunner('should-not-run') }));
     ctx.configure({
@@ -2441,6 +2496,17 @@ function countEvents(events: ReturnType<TestAgentContext['newEvents']>, type: st
   }).length;
 }
 
+function exactCompactionRefreshPrompt(workDir: string, agentsMd: string): string {
+  return [
+    `cwd:${workDir}`,
+    'os:Linux',
+    'shell:bash:/bin/bash',
+    `agents:<!-- From: ${join(workDir, 'AGENTS.md')} -->\n${agentsMd}`,
+    'ls:\u2514\u2500\u2500 AGENTS.md',
+    'extra:',
+  ].join('\n');
+}
+
 function oauthTestAgentOptions(
   getAccessToken: (options?: { readonly force?: boolean }) => Promise<string>,
 ): {

packages/agent-core-v2/test/profile/apply-profile.test.ts

@@ -16,6 +16,20 @@ const profile: ResolvedAgentProfile = {
   tools: [],
 };
 
+const exactProfile: ResolvedAgentProfile = {
+  name: 'exact-profile',
+  systemPrompt: (context) =>
+    [
+      `cwd:${context.cwd ?? ''}`,
+      `os:${context.osKind ?? ''}`,
+      `shell:${context.shellName ?? ''}:${context.shellPath ?? ''}`,
+      `agents:${context.agentsMd ?? ''}`,
+      `ls:${context.cwdListing ?? ''}`,
+      `extra:${context.additionalDirsInfo ?? ''}`,
+    ].join('\n'),
+  tools: ['Read', 'Write'],
+};
+
 describe('AgentProfileService.applyProfile', () => {
   let ctx: TestAgentContext;
   let homeDir: string;
@@ -56,6 +70,29 @@ describe('AgentProfileService.applyProfile', () => {
     expect(svc.getAgentsMdWarning()).toBeUndefined();
   });
 
+  it('renders the complete runtime context exactly', async () => {
+    await writeFile(join(workDir, 'AGENTS.md'), 'project instructions', 'utf-8');
+    const { profile: svc } = buildContext();
+
+    await svc.applyProfile(exactProfile);
+
+    expect(svc.data().systemPrompt).toBe(exactSystemPrompt(workDir, 'project instructions'));
+  });
+
+  it('refreshes the active profile system prompt exactly without resetting active tools', async () => {
+    await writeFile(join(workDir, 'AGENTS.md'), 'old instructions', 'utf-8');
+    const { profile: svc } = buildContext();
+    svc.update({ cwd: workDir });
+    await svc.applyProfile(exactProfile);
+    svc.update({ activeToolNames: ['Read'] });
+    await writeFile(join(workDir, 'AGENTS.md'), 'new instructions', 'utf-8');
+
+    await svc.refreshSystemPrompt();
+
+    expect(svc.data().systemPrompt).toBe(exactSystemPrompt(workDir, 'new instructions'));
+    expect(svc.getActiveToolNames()).toEqual(['Read']);
+  });
+
   it('caches an agents-md warning when the content exceeds the 32 KB soft budget', async () => {
     const largeContent = 'x'.repeat(40 * 1024);
     await writeFile(join(workDir, 'AGENTS.md'), largeContent, 'utf-8');
@@ -88,3 +125,14 @@ describe('AgentProfileService.applyProfile', () => {
     expect(svc.getAgentsMdWarning()).toBeUndefined();
   });
 });
+
+function exactSystemPrompt(workDir: string, agentsMd: string): string {
+  return [
+    `cwd:${workDir}`,
+    'os:Linux',
+    'shell:bash:/bin/bash',
+    `agents:<!-- From: ${join(workDir, 'AGENTS.md')} -->\n${agentsMd}`,
+    'ls:\u2514\u2500\u2500 AGENTS.md',
+    'extra:',
+  ].join('\n');
+}