diff --git a/src/cron/heartbeat.test.ts b/src/cron/heartbeat.test.ts
index 3981224..dd59a14 100644
--- a/src/cron/heartbeat.test.ts
+++ b/src/cron/heartbeat.test.ts
@@ -1,11 +1,15 @@
 import { describe, expect, it, vi, beforeEach, afterEach } from 'vitest';
-import { writeFileSync, mkdirSync, unlinkSync, rmSync } from 'node:fs';
+import { writeFileSync, mkdirSync, unlinkSync, rmSync, readFileSync, existsSync } from 'node:fs';
 import { resolve } from 'node:path';
-import { tmpdir } from 'node:os';
+import { tmpdir, homedir } from 'node:os';
+import { execSync } from 'node:child_process';
 import { HeartbeatService, type HeartbeatConfig } from './heartbeat.js';
 import { buildCustomHeartbeatPrompt, SILENT_MODE_PREFIX } from '../core/prompts.js';
 import type { AgentSession } from '../core/interfaces.js';
 import { addTodo } from '../todo/store.js';
+import { getCronLogPath } from '../utils/paths.js';
+
+const HEARTBEAT_LOG_PATH = getCronLogPath();
 
 // ── buildCustomHeartbeatPrompt ──────────────────────────────────────────
 
@@ -271,3 +275,143 @@ describe('HeartbeatService prompt resolution', () => {
     expect(bot.sendToAgent).toHaveBeenCalledTimes(1);
   });
 });
+
+// ── Memfs health check ─────────────────────────────────────────────────
+
+describe('HeartbeatService memfs health check', () => {
+  let tmpDir: string;
+  let memDir: string | undefined;
+  let originalDataDir: string | undefined;
+  let originalHome: string | undefined;
+  let testHome: string;
+
+  beforeEach(() => {
+    tmpDir = resolve(tmpdir(), `heartbeat-memfs-test-${Date.now()}`);
+    testHome = resolve(tmpDir, 'fake-home');
+    mkdirSync(tmpDir, { recursive: true });
+    mkdirSync(testHome, { recursive: true });
+    originalDataDir = process.env.DATA_DIR;
+    originalHome = process.env.HOME;
+    process.env.DATA_DIR = tmpDir;
+    process.env.HOME = testHome;
+  });
+
+  afterEach(() => {
+    if (originalDataDir === undefined) {
+      delete process.env.DATA_DIR;
+    } else {
+      process.env.DATA_DIR = originalDataDir;
+    }
+    if (originalHome === undefined) {
+      delete process.env.HOME;
+    } else {
+      process.env.HOME = originalHome;
+    }
+    try { rmSync(tmpDir, { recursive: true, force: true }); } catch { /* ignore */ }
+    memDir = undefined;
+  });
+
+  it('emits heartbeat_memfs_dirty when memfs directory has untracked files', async () => {
+    // Set up a real git repo to act as the memory directory
+    const agentId = 'agent-memfs-test-' + Date.now();
+    memDir = resolve(homedir(), '.letta', 'agents', agentId, 'memory');
+    mkdirSync(memDir, { recursive: true });
+    execSync('git init', { cwd: memDir, stdio: 'ignore' });
+    // Create an untracked file
+    writeFileSync(resolve(memDir, 'untracked.md'), 'test');
+
+    const bot = createMockBot();
+    (bot.getStatus as ReturnType<typeof vi.fn>).mockReturnValue({
+      agentId,
+      conversationId: null,
+      channels: [],
+    });
+
+    const service = new HeartbeatService(bot, createConfig({
+      workingDir: tmpDir,
+      memfs: true,
+    }));
+
+    // Access private method for direct testing
+    const checkMemfsHealth = (service as any).checkMemfsHealth.bind(service);
+
+    expect(() => checkMemfsHealth()).not.toThrow();
+    await new Promise((resolvePromise) => setTimeout(resolvePromise, 10));
+
+    const logContents = existsSync(HEARTBEAT_LOG_PATH)
+      ? readFileSync(HEARTBEAT_LOG_PATH, 'utf-8')
+      : '';
+    expect(logContents).toContain('heartbeat_memfs_dirty');
+    expect(logContents).toContain(agentId);
+  });
+
+  it('skips memfs check when memfs is disabled', async () => {
+    const bot = createMockBot();
+    const service = new HeartbeatService(bot, createConfig({
+      workingDir: tmpDir,
+      memfs: false,
+    }));
+
+    const getMemoryDir = (service as any).getMemoryDir.bind(service);
+    expect(getMemoryDir()).toBeNull();
+  });
+
+  it('skips memfs check when agent ID is not available', async () => {
+    const bot = createMockBot();
+    (bot.getStatus as ReturnType<typeof vi.fn>).mockReturnValue({
+      agentId: null,
+      conversationId: null,
+      channels: [],
+    });
+
+    const service = new HeartbeatService(bot, createConfig({
+      workingDir: tmpDir,
+      memfs: true,
+    }));
+
+    const getMemoryDir = (service as any).getMemoryDir.bind(service);
+    expect(getMemoryDir()).toBeNull();
+  });
+
+  it('resolves memory directory correctly when memfs is enabled', () => {
+    const bot = createMockBot();
+    (bot.getStatus as ReturnType<typeof vi.fn>).mockReturnValue({
+      agentId: 'agent-abc123',
+      conversationId: null,
+      channels: [],
+    });
+
+    const service = new HeartbeatService(bot, createConfig({
+      workingDir: tmpDir,
+      memfs: true,
+    }));
+
+    const getMemoryDir = (service as any).getMemoryDir.bind(service);
+    expect(getMemoryDir()).toBe(resolve(homedir(), '.letta', 'agents', 'agent-abc123', 'memory'));
+  });
+
+  it('still calls sendToAgent even when memfs check finds dirty files', async () => {
+    const agentId = 'agent-memfs-dirty-' + Date.now();
+    memDir = resolve(homedir(), '.letta', 'agents', agentId, 'memory');
+    mkdirSync(memDir, { recursive: true });
+    execSync('git init', { cwd: memDir, stdio: 'ignore' });
+    writeFileSync(resolve(memDir, 'dirty.md'), 'uncommitted content');
+
+    const bot = createMockBot();
+    (bot.getStatus as ReturnType<typeof vi.fn>).mockReturnValue({
+      agentId,
+      conversationId: null,
+      channels: [],
+    });
+
+    const service = new HeartbeatService(bot, createConfig({
+      workingDir: tmpDir,
+      memfs: true,
+    }));
+
+    await service.trigger();
+
+    // sendToAgent should still be called (memfs check is non-blocking)
+    expect(bot.sendToAgent).toHaveBeenCalledTimes(1);
+  });
+});
diff --git a/src/cron/heartbeat.ts b/src/cron/heartbeat.ts
index 3f94432..7b2e802 100644
--- a/src/cron/heartbeat.ts
+++ b/src/cron/heartbeat.ts
@@ -7,8 +7,10 @@
  * The agent must use `lettabot-message` CLI via Bash to contact the user.
  */
 
-import { appendFileSync, mkdirSync, readFileSync } from 'node:fs';
-import { resolve, dirname } from 'node:path';
+import { appendFileSync, existsSync, mkdirSync, readFileSync } from 'node:fs';
+import { resolve, dirname, join } from 'node:path';
+import { homedir } from 'node:os';
+import { execFileSync } from 'node:child_process';
 import type { AgentSession } from '../core/interfaces.js';
 import type { TriggerContext } from '../core/types.js';
 import { buildHeartbeatPrompt, buildCustomHeartbeatPrompt } from '../core/prompts.js';
@@ -49,6 +51,9 @@ export interface HeartbeatConfig {
   workingDir: string;
   agentKey: string;
   
+  // Whether memfs (git-backed memory filesystem) is enabled for this agent
+  memfs?: boolean;
+  
   // Custom heartbeat prompt (optional)
   prompt?: string;
   
@@ -82,6 +87,57 @@ export class HeartbeatService {
     }
     return Math.floor(raw * 60 * 1000);
   }
+
+  /**
+   * Resolve the memory directory for this agent.
+   * Returns null if memfs is disabled or agent ID is unavailable.
+   */
+  private getMemoryDir(): string | null {
+    if (!this.config.memfs) return null;
+    const agentId = this.bot.getStatus().agentId;
+    if (!agentId) return null;
+    return join(homedir(), '.letta', 'agents', agentId, 'memory');
+  }
+
+  /**
+   * Check if the memfs git repo has untracked or uncommitted files.
+   * Logs a warning if it does. Non-fatal: heartbeat proceeds regardless.
+   */
+  private checkMemfsHealth(): void {
+    const memoryDir = this.getMemoryDir();
+    if (!memoryDir) return;
+
+    if (!existsSync(memoryDir)) {
+      log.debug(`Memory directory does not exist yet: ${memoryDir}`);
+      return;
+    }
+
+    try {
+      const output = execFileSync('git', ['status', '--porcelain'], {
+        cwd: memoryDir,
+        encoding: 'utf-8',
+        timeout: 5000,
+      }).trim();
+
+      if (output) {
+        const lines = output.split('\n');
+        log.warn(
+          `Memory directory has ${lines.length} uncommitted/untracked file(s). ` +
+          `This may cause heartbeat failures. Run "cd ${memoryDir} && git add -A && git commit -m 'sync'" to fix. ` +
+          `Files: ${lines.slice(0, 5).join(', ')}${lines.length > 5 ? ` (and ${lines.length - 5} more)` : ''}`,
+        );
+        logEvent('heartbeat_memfs_dirty', {
+          memoryDir,
+          fileCount: lines.length,
+          files: lines.slice(0, 10),
+        });
+      }
+    } catch (err) {
+      log.warn(
+        `Failed to check memfs health in ${memoryDir}: ${err instanceof Error ? err.message : String(err)}`,
+      );
+    }
+  }
   
   /**
    * Start the heartbeat timer
@@ -168,6 +224,9 @@ export class HeartbeatService {
       }
     }
     
+    // Pre-flight: check for dirty memfs state that could cause session init failures
+    this.checkMemfsHealth();
+
     log.info(`Sending heartbeat to agent...`);
     
     logEvent('heartbeat_running', { 
@@ -226,10 +285,22 @@ export class HeartbeatService {
       });
       
     } catch (error) {
+      const errorMsg = error instanceof Error ? error.message : String(error);
       log.error('Error:', error);
-      logEvent('heartbeat_error', {
-        error: error instanceof Error ? error.message : String(error),
-      });
+
+      // Surface git/memfs-related errors with actionable diagnostics
+      if (/\b(git|memfs|memory)\b/i.test(errorMsg)) {
+        const memoryDir = this.getMemoryDir();
+        log.warn(
+          `Heartbeat failed due to a git/memfs error. ` +
+          `This often happens when the memory directory has untracked or uncommitted files. ` +
+          (memoryDir
+            ? `Check: cd ${memoryDir} && git status`
+            : `Enable memfs or check LETTA_AGENT_ID to diagnose.`),
+        );
+      }
+
+      logEvent('heartbeat_error', { error: errorMsg });
     }
   }
 }
diff --git a/src/main.ts b/src/main.ts
index 398ec4a..81aa8bf 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -455,6 +455,7 @@ async function main() {
       intervalMinutes: heartbeatConfig?.intervalMin ?? 240,
       skipRecentUserMinutes: heartbeatConfig?.skipRecentUserMin ?? globalConfig.heartbeatSkipRecentUserMin,
       agentKey: agentConfig.name,
+      memfs: resolvedMemfs,
       prompt: heartbeatConfig?.prompt || process.env.HEARTBEAT_PROMPT,
       promptFile: heartbeatConfig?.promptFile,
       workingDir: resolvedWorkingDir,