fix: add missing memfs init steps in headless mode + refactor (#941)

Co-authored-by: Letta <noreply@letta.com>

src/agent/memoryFilesystem.ts

@@ -2,7 +2,9 @@
  * Memory filesystem helpers.
  *
  * With git-backed memory, most sync/hash logic is removed.
- * This module retains: directory helpers and tree rendering.
+ * This module retains: directory helpers, tree rendering, and
+ * the shared memfs initialization logic used by both interactive
+ * and headless code paths.
  */
 
 import { existsSync, mkdirSync } from "node:fs";
@@ -129,3 +131,87 @@ export function renderMemoryFilesystemTree(
 
   return lines.join("\n");
 }
+
+// ----- Shared memfs initialization -----
+
+export interface ApplyMemfsFlagsResult {
+  /** Whether memfs was enabled, disabled, or unchanged */
+  action: "enabled" | "disabled" | "unchanged";
+  /** Path to the memory directory (when enabled) */
+  memoryDir?: string;
+  /** Summary from git pull (when pullOnExistingRepo is true and repo already existed) */
+  pullSummary?: string;
+}
+
+/**
+ * Apply --memfs / --no-memfs CLI flags (or /memfs enable) to an agent.
+ *
+ * Shared between interactive (index.ts), headless (headless.ts), and
+ * the /memfs enable command (App.tsx) to avoid duplicating the setup logic.
+ *
+ * Steps when enabling:
+ *   1. Validate Letta Cloud requirement
+ *   2. Persist memfs setting
+ *   3. Detach old API-based memory tools
+ *   4. Update system prompt to include memfs section
+ *   5. Add git-memory-enabled tag + clone/pull repo
+ *
+ * @throws {Error} if Letta Cloud validation fails or git setup fails
+ */
+export async function applyMemfsFlags(
+  agentId: string,
+  memfsFlag: boolean | undefined,
+  noMemfsFlag: boolean | undefined,
+  options?: { pullOnExistingRepo?: boolean },
+): Promise<ApplyMemfsFlagsResult> {
+  const { getServerUrl } = await import("./client");
+  const { settingsManager } = await import("../settings-manager");
+
+  // 1. Validate + persist setting
+  if (memfsFlag) {
+    const serverUrl = getServerUrl();
+    if (!serverUrl.includes("api.letta.com")) {
+      throw new Error(
+        "--memfs is only available on Letta Cloud (api.letta.com).",
+      );
+    }
+    settingsManager.setMemfsEnabled(agentId, true);
+  } else if (noMemfsFlag) {
+    settingsManager.setMemfsEnabled(agentId, false);
+  }
+
+  const isEnabled = settingsManager.isMemfsEnabled(agentId);
+
+  // 2. Detach old API-based memory tools when enabling
+  if (isEnabled && memfsFlag) {
+    const { detachMemoryTools } = await import("../tools/toolset");
+    await detachMemoryTools(agentId);
+  }
+
+  // 3. Update system prompt to include/exclude memfs section
+  if (memfsFlag || noMemfsFlag) {
+    const { updateAgentSystemPromptMemfs } = await import("./modify");
+    await updateAgentSystemPromptMemfs(agentId, isEnabled);
+  }
+
+  // 4. Add git tag + clone/pull repo
+  let pullSummary: string | undefined;
+  if (isEnabled) {
+    const { addGitMemoryTag, isGitRepo, cloneMemoryRepo, pullMemory } =
+      await import("./memoryGit");
+    await addGitMemoryTag(agentId);
+    if (!isGitRepo(agentId)) {
+      await cloneMemoryRepo(agentId);
+    } else if (options?.pullOnExistingRepo) {
+      const result = await pullMemory(agentId);
+      pullSummary = result.summary;
+    }
+  }
+
+  const action = memfsFlag ? "enabled" : noMemfsFlag ? "disabled" : "unchanged";
+  return {
+    action,
+    memoryDir: isEnabled ? getMemoryFilesystemRoot(agentId) : undefined,
+    pullSummary,
+  };
+}