diff --git a/src/agent/approval-execution.ts b/src/agent/approval-execution.ts
index cf2dd46..c53d4a7 100644
--- a/src/agent/approval-execution.ts
+++ b/src/agent/approval-execution.ts
@@ -114,6 +114,8 @@ const GLOBAL_LOCK_TOOLS = new Set([
   "KillBash",
   "run_shell_command",
   "RunShellCommand",
+  // Memory tool (file + git side effects)
+  "memory",
   "shell_command",
   "shell",
   "ShellCommand",
diff --git a/src/permissions/checker.ts b/src/permissions/checker.ts
index f13377a..d2a288a 100644
--- a/src/permissions/checker.ts
+++ b/src/permissions/checker.ts
@@ -727,6 +727,8 @@ function getDefaultDecision(
     "SearchFileContent",
     "WriteTodos",
     "ReadManyFiles",
+    // client-side memory tool is mutating + git side effects
+    // and should require approval by default
   ];
 
   if (autoAllowTools.includes(toolName)) {
diff --git a/src/tests/tools/memory-tool.test.ts b/src/tests/tools/memory-tool.test.ts
new file mode 100644
index 0000000..2d3e9d0
--- /dev/null
+++ b/src/tests/tools/memory-tool.test.ts
@@ -0,0 +1,209 @@
+import { afterEach, beforeEach, describe, expect, mock, test } from "bun:test";
+import { execFile as execFileCb } from "node:child_process";
+import { mkdtempSync, writeFileSync } from "node:fs";
+import { rm } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { promisify } from "node:util";
+
+const execFile = promisify(execFileCb);
+
+const TEST_AGENT_ID = "agent-test-memory-tool";
+const TEST_AGENT_NAME = "Bob";
+
+mock.module("../../agent/context", () => ({
+  getCurrentAgentId: () => TEST_AGENT_ID,
+}));
+
+mock.module("../../agent/client", () => ({
+  getClient: mock(() =>
+    Promise.resolve({
+      agents: {
+        retrieve: mock(() => Promise.resolve({ name: TEST_AGENT_NAME })),
+      },
+    }),
+  ),
+}));
+
+const { memory } = await import("../../tools/impl/Memory");
+
+async function runGit(cwd: string, args: string[]): Promise<string> {
+  const { stdout } = await execFile("git", args, { cwd });
+  return String(stdout ?? "").trim();
+}
+
+describe("memory tool", () => {
+  let tempRoot: string;
+  let memoryDir: string;
+  let remoteDir: string;
+
+  const originalMemoryDir = process.env.MEMORY_DIR;
+  const originalAgentId = process.env.AGENT_ID;
+  const originalAgentName = process.env.AGENT_NAME;
+
+  beforeEach(async () => {
+    tempRoot = mkdtempSync(join(tmpdir(), "letta-memory-tool-"));
+    memoryDir = join(tempRoot, "memory");
+    remoteDir = join(tempRoot, "remote.git");
+
+    // Bare remote
+    await execFile("git", ["init", "--bare", remoteDir]);
+
+    // Local memory repo
+    await execFile("git", ["init", "-b", "main", memoryDir]);
+    await runGit(memoryDir, ["config", "user.name", "setup"]);
+    await runGit(memoryDir, ["config", "user.email", "setup@example.com"]);
+    await runGit(memoryDir, ["remote", "add", "origin", remoteDir]);
+
+    writeFileSync(join(memoryDir, ".gitkeep"), "", "utf8");
+    await runGit(memoryDir, ["add", ".gitkeep"]);
+    await runGit(memoryDir, ["commit", "-m", "initial"]);
+    await runGit(memoryDir, ["push", "-u", "origin", "main"]);
+
+    process.env.MEMORY_DIR = memoryDir;
+    process.env.AGENT_ID = TEST_AGENT_ID;
+    process.env.AGENT_NAME = TEST_AGENT_NAME;
+  });
+
+  afterEach(async () => {
+    if (originalMemoryDir === undefined) delete process.env.MEMORY_DIR;
+    else process.env.MEMORY_DIR = originalMemoryDir;
+
+    if (originalAgentId === undefined) delete process.env.AGENT_ID;
+    else process.env.AGENT_ID = originalAgentId;
+
+    if (originalAgentName === undefined) delete process.env.AGENT_NAME;
+    else process.env.AGENT_NAME = originalAgentName;
+
+    if (tempRoot) {
+      await rm(tempRoot, { recursive: true, force: true });
+    }
+  });
+
+  test("requires reason", async () => {
+    await expect(
+      memory({
+        command: "create",
+        path: "system/test.md",
+        description: "test desc",
+      } as Parameters<typeof memory>[0]),
+    ).rejects.toThrow(/missing required parameter/i);
+  });
+
+  test("uses reason as commit message and agent identity as commit author", async () => {
+    const reason = "Create coding preferences block";
+
+    await memory({
+      command: "create",
+      reason,
+      path: "system/human/prefs/coding.md",
+      description: "The user's coding preferences.",
+      file_text: "The user likes explicit types.",
+    });
+
+    const logOutput = await runGit(memoryDir, [
+      "log",
+      "-1",
+      "--pretty=format:%s%n%an%n%ae",
+    ]);
+    const [subject, authorName, authorEmail] = logOutput.split("\n");
+
+    expect(subject).toBe(reason);
+    expect(authorName).toBe(TEST_AGENT_NAME);
+    expect(authorEmail).toBe(`${TEST_AGENT_ID}@letta.com`);
+
+    const remoteSubject = await execFile(
+      "git",
+      ["--git-dir", remoteDir, "log", "-1", "--pretty=format:%s", "main"],
+      {},
+    ).then((r) => String(r.stdout ?? "").trim());
+    expect(remoteSubject).toBe(reason);
+  });
+
+  test("returns error when push fails but keeps local commit", async () => {
+    await memory({
+      command: "create",
+      reason: "Seed notes",
+      path: "reference/history/notes.md",
+      description: "Notes block",
+      file_text: "old value",
+    });
+
+    await runGit(memoryDir, [
+      "remote",
+      "set-url",
+      "origin",
+      join(tempRoot, "missing-remote.git"),
+    ]);
+
+    const reason = "Update notes after remote failure";
+
+    await expect(
+      memory({
+        command: "str_replace",
+        reason,
+        path: "reference/history/notes.md",
+        old_string: "old value",
+        new_string: "new value",
+      }),
+    ).rejects.toThrow(/committed .* but push failed/i);
+
+    const subject = await runGit(memoryDir, [
+      "log",
+      "-1",
+      "--pretty=format:%s",
+    ]);
+    expect(subject).toBe(reason);
+  });
+
+  test("falls back to context agent id when AGENT_ID env is missing", async () => {
+    delete process.env.AGENT_ID;
+    delete process.env.LETTA_AGENT_ID;
+
+    const reason = "Create identity via context fallback";
+    await memory({
+      command: "create",
+      reason,
+      path: "system/human/identity.md",
+      description: "Identity block",
+      file_text: "Name: Bob",
+    });
+
+    const authorEmail = await runGit(memoryDir, [
+      "log",
+      "-1",
+      "--pretty=format:%ae",
+    ]);
+    expect(authorEmail).toBe(`${TEST_AGENT_ID}@letta.com`);
+  });
+
+  test("accepts relative file paths like system/contacts.md", async () => {
+    const reason = "Create contacts via relative path";
+
+    await memory({
+      command: "create",
+      reason,
+      path: "system/contacts.md",
+      description: "Contacts memory",
+      file_text: "Sarah: +1-555-0100",
+    });
+
+    const content = await runGit(memoryDir, [
+      "show",
+      "HEAD:system/contacts.md",
+    ]);
+    expect(content).toContain("description: Contacts memory");
+    expect(content).toContain("Sarah: +1-555-0100");
+  });
+
+  test("rejects /memories-style paths", async () => {
+    await expect(
+      memory({
+        command: "create",
+        reason: "should fail",
+        path: "/memories/contacts",
+        description: "Contacts memory",
+      }),
+    ).rejects.toThrow(/relative path like system\/contacts\.md/i);
+  });
+});
diff --git a/src/tools/descriptions/Memory.md b/src/tools/descriptions/Memory.md
new file mode 100644
index 0000000..a6bc3c1
--- /dev/null
+++ b/src/tools/descriptions/Memory.md
@@ -0,0 +1,39 @@
+# Memory
+A convinience tool for memories stored in the memory directory (`$MEMORY_DIR`) that automatically commits and pushes changes. 
+
+Files stored inside of `system/` eventually become part of the agent's system prompt, so are always in the context window and do not need to be re-read. Other files only have metadata in the system prompt, so may need to be explicitly read to be updated. 
+
+Supported operations on memory files:  
+- `str_replace`
+- `insert`
+- `delete`
+- `rename` (path rename or description update mode)
+- `create`
+More general operations can be performanced through directory modifying the files. 
+
+Path formats accepted:
+- relative memory file paths (e.g. `system/contacts.md`, `reference/project/team.md`)
+
+Note: absolute paths and `/memories/...` paths are not supported by this client-side tool.
+
+Examples:
+
+```python
+# Replace text in a memory file 
+memory(command="str_replace", reason="Update theme preference", path="system/human/preferences.md", old_string="theme: dark", new_string="theme: light")
+
+# Insert text at line 5
+memory(command="insert", reason="Add note about meeting", path="reference/history/meeting-notes.md", insert_line=5, insert_text="New note here")
+
+# Delete a memory file 
+memory(command="delete", reason="Remove stale notes", path="reference/history/old_notes.md")
+
+# Rename a memory file 
+memory(command="rename", reason="Promote temp notes", old_path="reference/history/temp.md", new_path="reference/history/permanent.md")
+
+# Create a block with starting text
+memory(command="create", reason="Track coding preferences", path="system/human/prefs/coding.md", description="The user's coding preferences.", file_text="The user seems to add type hints to all of their Python code.")
+
+# Create an empty block
+memory(command="create", reason="Create coding preferences block", path="reference/history/coding_preferences.md", description="The user's coding preferences.")
+```
diff --git a/src/tools/impl/Memory.ts b/src/tools/impl/Memory.ts
new file mode 100644
index 0000000..14475a6
--- /dev/null
+++ b/src/tools/impl/Memory.ts
@@ -0,0 +1,582 @@
+import { execFile as execFileCb } from "node:child_process";
+import { existsSync } from "node:fs";
+import { mkdir, readFile, rename, unlink, writeFile } from "node:fs/promises";
+import { homedir } from "node:os";
+import { dirname, isAbsolute, relative, resolve } from "node:path";
+import { promisify } from "node:util";
+import { getClient } from "../../agent/client";
+import { getCurrentAgentId } from "../../agent/context";
+import { validateRequiredParams } from "./validation";
+
+const execFile = promisify(execFileCb);
+
+type MemoryCommand = "str_replace" | "insert" | "delete" | "rename" | "create";
+
+interface MemoryArgs {
+  command: MemoryCommand;
+  reason: string;
+  path?: string;
+  old_path?: string;
+  new_path?: string;
+  old_string?: string;
+  new_string?: string;
+  insert_line?: number;
+  insert_text?: string;
+  description?: string;
+  file_text?: string;
+  limit?: number;
+}
+
+async function getAgentIdentity(): Promise<{
+  agentId: string;
+  agentName: string;
+}> {
+  const envAgentId = (
+    process.env.AGENT_ID ||
+    process.env.LETTA_AGENT_ID ||
+    ""
+  ).trim();
+  const contextAgentId = (() => {
+    try {
+      return getCurrentAgentId().trim();
+    } catch {
+      return "";
+    }
+  })();
+  const agentId = contextAgentId || envAgentId;
+
+  if (!agentId) {
+    throw new Error("memory: unable to resolve agent id for git author email");
+  }
+
+  let agentName = "";
+  try {
+    const client = await getClient();
+    const agent = await client.agents.retrieve(agentId);
+    agentName = (agent.name || "").trim();
+  } catch {
+    // Keep best-effort fallback below
+  }
+
+  if (!agentName) {
+    agentName = (process.env.AGENT_NAME || "").trim() || agentId;
+  }
+
+  return { agentId, agentName };
+}
+
+interface MemoryResult {
+  message: string;
+}
+
+interface ParsedMemoryFile {
+  frontmatter: {
+    description: string;
+    limit: number;
+    read_only?: string;
+  };
+  body: string;
+}
+
+const DEFAULT_LIMIT = 2000;
+
+export async function memory(args: MemoryArgs): Promise<MemoryResult> {
+  validateRequiredParams(args, ["command", "reason"], "memory");
+
+  const reason = args.reason.trim();
+  if (!reason) {
+    throw new Error("memory: 'reason' must be a non-empty string");
+  }
+
+  const memoryDir = resolveMemoryDir();
+  ensureMemoryRepo(memoryDir);
+
+  let affectedPaths: string[] = [];
+  const command = args.command;
+
+  if (command === "create") {
+    const pathArg = requireString(args.path, "path", "create");
+    const description = requireString(
+      args.description,
+      "description",
+      "create",
+    );
+    const label = normalizeMemoryLabel(pathArg, "path");
+    const filePath = resolveMemoryFilePath(memoryDir, label);
+    const relPath = toRepoRelative(memoryDir, filePath);
+
+    if (existsSync(filePath)) {
+      throw new Error(`memory create: block already exists at ${pathArg}`);
+    }
+
+    const limit = args.limit ?? DEFAULT_LIMIT;
+    if (!Number.isInteger(limit) || limit <= 0) {
+      throw new Error("memory create: 'limit' must be a positive integer");
+    }
+
+    const body = args.file_text ?? "";
+    const rendered = renderMemoryFile(
+      {
+        description,
+        limit,
+      },
+      body,
+    );
+
+    await mkdir(dirname(filePath), { recursive: true });
+    await writeFile(filePath, rendered, "utf8");
+    affectedPaths = [relPath];
+  } else if (command === "str_replace") {
+    const pathArg = requireString(args.path, "path", "str_replace");
+    const oldString = requireString(
+      args.old_string,
+      "old_string",
+      "str_replace",
+    );
+    const newString = requireString(
+      args.new_string,
+      "new_string",
+      "str_replace",
+    );
+
+    const label = normalizeMemoryLabel(pathArg, "path");
+    const filePath = resolveMemoryFilePath(memoryDir, label);
+    const relPath = toRepoRelative(memoryDir, filePath);
+    const file = await loadEditableMemoryFile(filePath, pathArg);
+
+    const idx = file.body.indexOf(oldString);
+    if (idx === -1) {
+      throw new Error(
+        "memory str_replace: old_string was not found in the target memory block",
+      );
+    }
+
+    const nextBody = `${file.body.slice(0, idx)}${newString}${file.body.slice(idx + oldString.length)}`;
+    const rendered = renderMemoryFile(file.frontmatter, nextBody);
+    await writeFile(filePath, rendered, "utf8");
+    affectedPaths = [relPath];
+  } else if (command === "insert") {
+    const pathArg = requireString(args.path, "path", "insert");
+    const insertText = requireString(args.insert_text, "insert_text", "insert");
+
+    if (
+      typeof args.insert_line !== "number" ||
+      Number.isNaN(args.insert_line)
+    ) {
+      throw new Error("memory insert: 'insert_line' must be a number");
+    }
+
+    const label = normalizeMemoryLabel(pathArg, "path");
+    const filePath = resolveMemoryFilePath(memoryDir, label);
+    const relPath = toRepoRelative(memoryDir, filePath);
+    const file = await loadEditableMemoryFile(filePath, pathArg);
+
+    const lineNumber = Math.max(1, Math.floor(args.insert_line));
+    const existingLines = file.body.length > 0 ? file.body.split("\n") : [];
+    const insertion = insertText.split("\n");
+    const insertionIndex = Math.min(
+      Math.max(lineNumber - 1, 0),
+      existingLines.length,
+    );
+
+    existingLines.splice(insertionIndex, 0, ...insertion);
+    const nextBody = existingLines.join("\n");
+
+    const rendered = renderMemoryFile(file.frontmatter, nextBody);
+    await writeFile(filePath, rendered, "utf8");
+    affectedPaths = [relPath];
+  } else if (command === "delete") {
+    const pathArg = requireString(args.path, "path", "delete");
+    const label = normalizeMemoryLabel(pathArg, "path");
+    const filePath = resolveMemoryFilePath(memoryDir, label);
+    const relPath = toRepoRelative(memoryDir, filePath);
+
+    await loadEditableMemoryFile(filePath, pathArg);
+    await unlink(filePath);
+    affectedPaths = [relPath];
+  } else if (command === "rename") {
+    const hasDescriptionUpdate =
+      typeof args.path === "string" &&
+      args.path.trim().length > 0 &&
+      typeof args.description === "string" &&
+      args.description.trim().length > 0 &&
+      !args.old_path &&
+      !args.new_path;
+
+    if (hasDescriptionUpdate) {
+      const pathArg = requireString(args.path, "path", "rename");
+      const newDescription = requireString(
+        args.description,
+        "description",
+        "rename description update",
+      );
+
+      const label = normalizeMemoryLabel(pathArg, "path");
+      const filePath = resolveMemoryFilePath(memoryDir, label);
+      const relPath = toRepoRelative(memoryDir, filePath);
+      const file = await loadEditableMemoryFile(filePath, pathArg);
+
+      const rendered = renderMemoryFile(
+        {
+          ...file.frontmatter,
+          description: newDescription,
+        },
+        file.body,
+      );
+      await writeFile(filePath, rendered, "utf8");
+      affectedPaths = [relPath];
+    } else {
+      const oldPathArg = requireString(args.old_path, "old_path", "rename");
+      const newPathArg = requireString(args.new_path, "new_path", "rename");
+
+      const oldLabel = normalizeMemoryLabel(oldPathArg, "old_path");
+      const newLabel = normalizeMemoryLabel(newPathArg, "new_path");
+
+      const oldFilePath = resolveMemoryFilePath(memoryDir, oldLabel);
+      const newFilePath = resolveMemoryFilePath(memoryDir, newLabel);
+
+      const oldRelPath = toRepoRelative(memoryDir, oldFilePath);
+      const newRelPath = toRepoRelative(memoryDir, newFilePath);
+
+      if (existsSync(newFilePath)) {
+        throw new Error(
+          `memory rename: destination already exists at ${newPathArg}`,
+        );
+      }
+
+      await loadEditableMemoryFile(oldFilePath, oldPathArg);
+      await mkdir(dirname(newFilePath), { recursive: true });
+      await rename(oldFilePath, newFilePath);
+      affectedPaths = [oldRelPath, newRelPath];
+    }
+  } else {
+    throw new Error(`Unsupported memory command: ${command}`);
+  }
+
+  affectedPaths = Array.from(new Set(affectedPaths)).filter(
+    (p) => p.length > 0,
+  );
+  if (affectedPaths.length === 0) {
+    return { message: `Memory ${command} completed with no changed paths.` };
+  }
+
+  const commitResult = await commitAndPush(memoryDir, affectedPaths, reason);
+  if (!commitResult.committed) {
+    return {
+      message: `Memory ${command} made no effective changes; skipped commit and push.`,
+    };
+  }
+
+  return {
+    message: `Memory ${command} applied and pushed (${commitResult.sha?.slice(0, 7) ?? "unknown"}).`,
+  };
+}
+
+function resolveMemoryDir(): string {
+  const direct = process.env.MEMORY_DIR || process.env.LETTA_MEMORY_DIR;
+  if (direct && direct.trim().length > 0) {
+    return resolve(direct);
+  }
+
+  const contextAgentId = (() => {
+    try {
+      return getCurrentAgentId().trim();
+    } catch {
+      return "";
+    }
+  })();
+
+  const agentId =
+    contextAgentId ||
+    (process.env.AGENT_ID || process.env.LETTA_AGENT_ID || "").trim();
+  if (agentId && agentId.trim().length > 0) {
+    return resolve(homedir(), ".letta", "agents", agentId, "memory");
+  }
+
+  throw new Error(
+    "memory: unable to resolve memory directory. Ensure MEMORY_DIR (or AGENT_ID) is available.",
+  );
+}
+
+function ensureMemoryRepo(memoryDir: string): void {
+  if (!existsSync(memoryDir)) {
+    throw new Error(`memory: memory directory does not exist: ${memoryDir}`);
+  }
+  if (!existsSync(resolve(memoryDir, ".git"))) {
+    throw new Error(
+      `memory: ${memoryDir} is not a git repository. This tool requires a git-backed memory filesystem.`,
+    );
+  }
+}
+
+function normalizeMemoryLabel(inputPath: string, fieldName: string): string {
+  const raw = inputPath.trim();
+  if (!raw) {
+    throw new Error(`memory: '${fieldName}' must be a non-empty string`);
+  }
+
+  const normalized = raw.replace(/\\/g, "/");
+
+  if (/^[a-zA-Z]:\//.test(normalized)) {
+    throw new Error(
+      `memory: '${fieldName}' must be a memory-relative file path, not an absolute host path`,
+    );
+  }
+
+  if (normalized.startsWith("~/") || normalized.startsWith("$HOME/")) {
+    throw new Error(
+      `memory: '${fieldName}' must be a memory-relative file path, not a home-relative filesystem path`,
+    );
+  }
+
+  if (normalized.startsWith("/")) {
+    throw new Error(
+      `memory: '${fieldName}' must be a relative path like system/contacts.md`,
+    );
+  }
+
+  let label = normalized;
+  // Accept optional leading `memory/` directory segment.
+  label = label.replace(/^memory\//, "");
+
+  // Normalize away a trailing .md extension for all input styles.
+  label = label.replace(/\.md$/, "");
+
+  if (!label) {
+    throw new Error(`memory: '${fieldName}' resolves to an empty memory label`);
+  }
+
+  const segments = label.split("/").filter(Boolean);
+  if (segments.length === 0) {
+    throw new Error(`memory: '${fieldName}' resolves to an empty memory label`);
+  }
+
+  for (const segment of segments) {
+    if (segment === "." || segment === "..") {
+      throw new Error(
+        `memory: '${fieldName}' contains invalid path traversal segment`,
+      );
+    }
+    if (segment.includes("\0")) {
+      throw new Error(`memory: '${fieldName}' contains invalid null bytes`);
+    }
+  }
+
+  return segments.join("/");
+}
+
+function resolveMemoryFilePath(memoryDir: string, label: string): string {
+  const absolute = resolve(memoryDir, `${label}.md`);
+  const rel = relative(memoryDir, absolute);
+  if (rel.startsWith("..") || isAbsolute(rel)) {
+    throw new Error("memory: resolved path escapes memory directory");
+  }
+  return absolute;
+}
+
+function toRepoRelative(memoryDir: string, absolutePath: string): string {
+  const rel = relative(memoryDir, absolutePath);
+  if (!rel || rel.startsWith("..") || isAbsolute(rel)) {
+    throw new Error("memory: path is outside memory repository");
+  }
+  return rel.replace(/\\/g, "/");
+}
+
+async function loadEditableMemoryFile(
+  filePath: string,
+  sourcePath: string,
+): Promise<ParsedMemoryFile> {
+  const content = await readFile(filePath, "utf8").catch((error) => {
+    const message = error instanceof Error ? error.message : String(error);
+    throw new Error(`memory: failed to read ${sourcePath}: ${message}`);
+  });
+
+  const parsed = parseMemoryFile(content);
+  if (parsed.frontmatter.read_only === "true") {
+    throw new Error(
+      `memory: ${sourcePath} is read_only and cannot be modified`,
+    );
+  }
+  return parsed;
+}
+
+function parseMemoryFile(content: string): ParsedMemoryFile {
+  const match = content.match(/^---\r?\n([\s\S]*?)\r?\n---\r?\n?([\s\S]*)$/);
+  if (!match) {
+    throw new Error("memory: target file is missing required frontmatter");
+  }
+
+  const frontmatterText = match[1] ?? "";
+  const body = match[2] ?? "";
+
+  let description: string | undefined;
+  let limit: number | undefined;
+  let readOnly: string | undefined;
+
+  for (const line of frontmatterText.split(/\r?\n/)) {
+    const idx = line.indexOf(":");
+    if (idx <= 0) continue;
+    const key = line.slice(0, idx).trim();
+    const value = line.slice(idx + 1).trim();
+
+    if (key === "description") {
+      description = value;
+    } else if (key === "limit") {
+      const parsedLimit = Number.parseInt(value, 10);
+      if (!Number.isNaN(parsedLimit)) {
+        limit = parsedLimit;
+      }
+    } else if (key === "read_only") {
+      readOnly = value;
+    }
+  }
+
+  if (!description || !description.trim()) {
+    throw new Error("memory: target file frontmatter is missing 'description'");
+  }
+  if (!limit || !Number.isInteger(limit) || limit <= 0) {
+    throw new Error(
+      "memory: target file frontmatter is missing a valid positive 'limit'",
+    );
+  }
+
+  return {
+    frontmatter: {
+      description,
+      limit,
+      ...(readOnly !== undefined ? { read_only: readOnly } : {}),
+    },
+    body,
+  };
+}
+
+function renderMemoryFile(
+  frontmatter: { description: string; limit: number; read_only?: string },
+  body: string,
+): string {
+  const description = frontmatter.description.trim();
+  if (!description) {
+    throw new Error("memory: 'description' must not be empty");
+  }
+  if (!Number.isInteger(frontmatter.limit) || frontmatter.limit <= 0) {
+    throw new Error("memory: 'limit' must be a positive integer");
+  }
+
+  const lines = [
+    "---",
+    `description: ${sanitizeFrontmatterValue(description)}`,
+    `limit: ${frontmatter.limit}`,
+  ];
+
+  if (frontmatter.read_only !== undefined) {
+    lines.push(`read_only: ${frontmatter.read_only}`);
+  }
+
+  lines.push("---");
+
+  const header = lines.join("\n");
+  if (!body) {
+    return `${header}\n`;
+  }
+  return `${header}\n${body}`;
+}
+
+function sanitizeFrontmatterValue(value: string): string {
+  return value.replace(/\r?\n/g, " ").trim();
+}
+
+async function runGit(
+  memoryDir: string,
+  args: string[],
+): Promise<{ stdout: string; stderr: string }> {
+  try {
+    const result = await execFile("git", args, {
+      cwd: memoryDir,
+      maxBuffer: 10 * 1024 * 1024,
+      env: {
+        ...process.env,
+        PAGER: "cat",
+        GIT_PAGER: "cat",
+      },
+    });
+
+    return {
+      stdout: result.stdout?.toString() ?? "",
+      stderr: result.stderr?.toString() ?? "",
+    };
+  } catch (error) {
+    const stderr =
+      typeof error === "object" && error !== null && "stderr" in error
+        ? String((error as { stderr?: string }).stderr ?? "")
+        : "";
+    const stdout =
+      typeof error === "object" && error !== null && "stdout" in error
+        ? String((error as { stdout?: string }).stdout ?? "")
+        : "";
+    const message = error instanceof Error ? error.message : String(error);
+
+    throw new Error(
+      `git ${args.join(" ")} failed: ${stderr || stdout || message}`.trim(),
+    );
+  }
+}
+
+async function commitAndPush(
+  memoryDir: string,
+  pathspecs: string[],
+  reason: string,
+): Promise<{ committed: boolean; sha?: string }> {
+  await runGit(memoryDir, ["add", "-A", "--", ...pathspecs]);
+
+  const status = await runGit(memoryDir, [
+    "status",
+    "--porcelain",
+    "--",
+    ...pathspecs,
+  ]);
+  if (!status.stdout.trim()) {
+    return { committed: false };
+  }
+
+  const { agentId, agentName } = await getAgentIdentity();
+  const authorName = agentName.trim() || agentId;
+  const authorEmail = `${agentId}@letta.com`;
+
+  await runGit(memoryDir, [
+    "-c",
+    `user.name=${authorName}`,
+    "-c",
+    `user.email=${authorEmail}`,
+    "commit",
+    "-m",
+    reason,
+  ]);
+
+  const head = await runGit(memoryDir, ["rev-parse", "HEAD"]);
+  const sha = head.stdout.trim();
+
+  try {
+    await runGit(memoryDir, ["push"]);
+  } catch (error) {
+    const message = error instanceof Error ? error.message : String(error);
+    throw new Error(
+      `Memory changes were committed (${sha.slice(0, 7)}) but push failed: ${message}`,
+    );
+  }
+
+  return {
+    committed: true,
+    sha,
+  };
+}
+
+function requireString(
+  value: string | undefined,
+  field: string,
+  command: string,
+): string {
+  if (typeof value !== "string" || value.trim().length === 0) {
+    throw new Error(`memory ${command}: '${field}' must be a non-empty string`);
+  }
+  return value;
+}
diff --git a/src/tools/manager.ts b/src/tools/manager.ts
index ef0a466..e67fd6d 100644
--- a/src/tools/manager.ts
+++ b/src/tools/manager.ts
@@ -103,6 +103,7 @@ export const ANTHROPIC_DEFAULT_TOOLS: ToolName[] = [
   "TaskStop",
   // "MultiEdit",
   // "LS",
+  "memory",
   "Read",
   "Skill",
   "Task",
@@ -115,6 +116,7 @@ export const OPENAI_DEFAULT_TOOLS: ToolName[] = [
   // TODO(codex-parity): add once request_user_input tool exists in raw codex path.
   // "request_user_input",
   "apply_patch",
+  "memory",
   "update_plan",
   "view_image",
 ];
@@ -125,6 +127,7 @@ export const GEMINI_DEFAULT_TOOLS: ToolName[] = [
   "list_directory",
   "glob_gemini",
   "search_file_content",
+  "memory",
   "replace",
   "write_file_gemini",
   "write_todos",
@@ -139,6 +142,7 @@ export const OPENAI_PASCAL_TOOLS: ToolName[] = [
   "AskUserQuestion",
   "EnterPlanMode",
   "ExitPlanMode",
+  "memory",
   "Task",
   "TaskOutput",
   "TaskStop",
@@ -155,6 +159,7 @@ export const GEMINI_PASCAL_TOOLS: ToolName[] = [
   "AskUserQuestion",
   "EnterPlanMode",
   "ExitPlanMode",
+  "memory",
   "Skill",
   "Task",
   // Standard Gemini tools
@@ -183,6 +188,7 @@ const TOOL_PERMISSIONS: Record<ToolName, { requiresApproval: boolean }> = {
   KillBash: { requiresApproval: true },
   TaskStop: { requiresApproval: true },
   LS: { requiresApproval: false },
+  memory: { requiresApproval: true },
   MultiEdit: { requiresApproval: true },
   Read: { requiresApproval: false },
   view_image: { requiresApproval: false },
diff --git a/src/tools/schemas/Memory.json b/src/tools/schemas/Memory.json
new file mode 100644
index 0000000..89e6fed
--- /dev/null
+++ b/src/tools/schemas/Memory.json
@@ -0,0 +1,57 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "type": "object",
+  "properties": {
+    "command": {
+      "type": "string",
+      "enum": ["str_replace", "insert", "delete", "rename", "create"],
+      "description": "Memory operation to perform"
+    },
+    "reason": {
+      "type": "string",
+      "description": "Required commit message for this memory change. Used as the git commit message."
+    },
+    "path": {
+      "type": "string",
+      "description": "Target memory file path relative to memory root (e.g. system/contacts.md)"
+    },
+    "old_path": {
+      "type": "string",
+      "description": "Source memory file path for rename operations (e.g. system/temp.md)"
+    },
+    "new_path": {
+      "type": "string",
+      "description": "Destination memory file path for rename operations (e.g. system/permanent.md)"
+    },
+    "old_string": {
+      "type": "string",
+      "description": "Text to replace in str_replace"
+    },
+    "new_string": {
+      "type": "string",
+      "description": "Replacement text for str_replace"
+    },
+    "insert_line": {
+      "type": "number",
+      "description": "1-indexed line number for insert"
+    },
+    "insert_text": {
+      "type": "string",
+      "description": "Text to insert"
+    },
+    "description": {
+      "type": "string",
+      "description": "Block description (required for create, or used with rename + path to update description)"
+    },
+    "file_text": {
+      "type": "string",
+      "description": "Initial block content for create"
+    },
+    "limit": {
+      "type": "number",
+      "description": "Optional positive integer limit for create"
+    }
+  },
+  "required": ["command", "reason"],
+  "additionalProperties": false
+}
diff --git a/src/tools/toolDefinitions.ts b/src/tools/toolDefinitions.ts
index d8189e8..5879ebd 100644
--- a/src/tools/toolDefinitions.ts
+++ b/src/tools/toolDefinitions.ts
@@ -14,6 +14,7 @@ import KillBashDescription from "./descriptions/KillBash.md";
 import ListDirCodexDescription from "./descriptions/ListDirCodex.md";
 import ListDirectoryGeminiDescription from "./descriptions/ListDirectoryGemini.md";
 import LSDescription from "./descriptions/LS.md";
+import MemoryDescription from "./descriptions/Memory.md";
 import MultiEditDescription from "./descriptions/MultiEdit.md";
 import ReadDescription from "./descriptions/Read.md";
 import ReadFileCodexDescription from "./descriptions/ReadFileCodex.md";
@@ -51,6 +52,7 @@ import { kill_bash } from "./impl/KillBash";
 import { list_dir } from "./impl/ListDirCodex";
 import { list_directory } from "./impl/ListDirectoryGemini";
 import { ls } from "./impl/LS";
+import { memory } from "./impl/Memory";
 import { multi_edit } from "./impl/MultiEdit";
 import { read } from "./impl/Read";
 import { read_file } from "./impl/ReadFileCodex";
@@ -88,6 +90,7 @@ import KillBashSchema from "./schemas/KillBash.json";
 import ListDirCodexSchema from "./schemas/ListDirCodex.json";
 import ListDirectoryGeminiSchema from "./schemas/ListDirectoryGemini.json";
 import LSSchema from "./schemas/LS.json";
+import MemorySchema from "./schemas/Memory.json";
 import MultiEditSchema from "./schemas/MultiEdit.json";
 import ReadSchema from "./schemas/Read.json";
 import ReadFileCodexSchema from "./schemas/ReadFileCodex.json";
@@ -179,6 +182,11 @@ const toolDefinitions = {
     description: LSDescription.trim(),
     impl: ls as unknown as ToolImplementation,
   },
+  memory: {
+    schema: MemorySchema,
+    description: MemoryDescription.trim(),
+    impl: memory as unknown as ToolImplementation,
+  },
   MultiEdit: {
     schema: MultiEditSchema,
     description: MultiEditDescription.trim(),