diff --git a/claims.json b/claims.json
index d54a3d4..dc9c5c5 100644
--- a/claims.json
+++ b/claims.json
@@ -14,8 +14,8 @@
     "networkMillis": 300
   },
   "tests": {
-    "count": 1505,
-    "assertions": 7218,
-    "files": 236
+    "count": 1507,
+    "assertions": 7226,
+    "files": 237
   }
 }
diff --git a/src/cli.ts b/src/cli.ts
index 5dd643c..a3cc53b 100644
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -30,6 +30,8 @@ import {
   handleHarvestAutoCommand,
   handleReindexCommand,
 } from "./cli/retrieval.ts";
+import { handleEnclaveCommand } from "./cli/enclave.ts";
+import { handleOverlayCommand } from "./cli/branch.ts";
 import { handleProjectCommand } from "./cli/project.ts";
 import { handleCurrentCommand, handleUserCommand, handleCoreCommand } from "./cli/persona.ts";
 import { handleEmbedCommand } from "./cli/embed.ts";
@@ -403,6 +405,10 @@ export async function main(argv: string[]): Promise<number> {
     // R23 Versioning Commands
     case "branch":
       return handleBranchCommand(parsed);
+    case "enclave":
+      return handleEnclaveCommand(parsed);
+    case "overlay":
+      return handleOverlayCommand(parsed);
     case "checkout":
       return handleCheckoutCommand(parsed);
     case "blame":
diff --git a/src/cli/branch.ts b/src/cli/branch.ts
index c98fd1a..bb40032 100644
--- a/src/cli/branch.ts
+++ b/src/cli/branch.ts
@@ -9,7 +9,7 @@ import {
   mergeBranchOverlay,
 } from "../store/branch.ts";
 
-export async function handleBranchCommand({ positional, flags }: ParsedArgs): Promise<number> {
+export async function handleOverlayCommand({ positional, flags }: ParsedArgs): Promise<number> {
   const ctx = requireRoot(flags);
   if (!ctx) return 1;
   const sub = positional[0] ?? "show";
@@ -51,6 +51,6 @@ export async function handleBranchCommand({ positional, flags }: ParsedArgs): Pr
       return 0;
     }
     default:
-      return usageError(`unknown branch subcommand '${sub}' (expected list | create | show | entries | merge | drop)`);
+      return usageError(`unknown overlay subcommand '${sub}' (expected list | create | show | entries | merge | drop)`);
   }
 }
diff --git a/src/cli/enclave.ts b/src/cli/enclave.ts
new file mode 100644
index 0000000..76ab5f4
--- /dev/null
+++ b/src/cli/enclave.ts
@@ -0,0 +1,49 @@
+import { randomUUID } from "node:crypto";
+import { requireRoot, usageError } from "./shared.ts";
+import type { ParsedArgs } from "./shared.ts";
+import { createEnclave, listEnclaveEntries, putEnclaveEntry } from "../store/enclaves.ts";
+import type { MemoryEntry, MemoryType } from "../types.ts";
+
+export async function handleEnclaveCommand({ positional, flags }: ParsedArgs): Promise<number> {
+  const ctx = requireRoot(flags);
+  if (!ctx) return 1;
+  const sub = positional[0];
+  const client = positional[1];
+  if (!sub || !client) return usageError("enclave requires <create|list|put> <client>");
+  const division = flags["division"] ?? "default";
+
+  switch (sub) {
+    case "create":
+      createEnclave(ctx.memoryDir, client, division);
+      console.log(`enclave ready: ${client}/${division}`);
+      return 0;
+    case "list": {
+      const entries = listEnclaveEntries(ctx.memoryDir, client, division);
+      console.log(`${client}/${division}: ${entries.length} entr${entries.length === 1 ? "y" : "ies"}`);
+      for (const entry of entries) console.log(`  ${entry.id} ${entry.type} ${entry.title}`);
+      return 0;
+    }
+    case "put": {
+      const content = positional[2];
+      if (!content) return usageError("enclave put requires <content>");
+      const id = `m_${Date.now()}_${randomUUID().slice(0, 8)}`;
+      const now = new Date().toISOString();
+      const entry: MemoryEntry = {
+        id,
+        title: content.slice(0, 80),
+        content,
+        project: client,
+        type: (flags["type"] as MemoryType) ?? "discovery",
+        status: "confirmed",
+        created_at: now,
+        updated_at: now,
+        tags: [],
+      } as MemoryEntry;
+      putEnclaveEntry(ctx.memoryDir, client, entry, division);
+      console.log(`stored ${id} in ${client}/${division}`);
+      return 0;
+    }
+    default:
+      return usageError(`unknown enclave subcommand '${sub}' (expected create | list | put)`);
+  }
+}
diff --git a/src/store/enclaves.ts b/src/store/enclaves.ts
new file mode 100644
index 0000000..406b91b
--- /dev/null
+++ b/src/store/enclaves.ts
@@ -0,0 +1,114 @@
+import { createCipheriv, createDecipheriv, createHash, randomBytes, scryptSync } from "node:crypto";
+import { chmodSync, existsSync, mkdirSync, readFileSync, renameSync, writeFileSync } from "node:fs";
+import { join } from "node:path";
+import type { MemoryEntry } from "../types.ts";
+
+const VERSION = 1;
+
+export interface EnclaveEnvelope {
+  version: number;
+  client: string;
+  division: string;
+  salt: string;
+  iv: string;
+  tag: string;
+  ciphertext: string;
+}
+
+function safeName(value: string): string {
+  return value.replace(/[^A-Za-z0-9._-]/g, "_");
+}
+
+export function enclavePath(memoryDir: string, client: string, division: string = "default"): string {
+  return join(memoryDir, "enclaves", safeName(client), `${safeName(division)}.enc.json`);
+}
+
+function loadMasterKey(memoryDir: string): Buffer {
+  const env = process.env.MUSE_ENCLAVE_KEY;
+  if (env) {
+    const fromEnv = /^[0-9a-fA-F]{64}$/.test(env) ? Buffer.from(env, "hex") : createHash("sha256").update(env).digest();
+    return fromEnv;
+  }
+  const keyPath = join(memoryDir, "enclave.key");
+  if (existsSync(keyPath)) {
+    const stored = readFileSync(keyPath, "utf8").trim();
+    if (!/^[0-9a-fA-F]{64}$/.test(stored)) throw new Error(`Invalid enclave key at ${keyPath}`);
+    return Buffer.from(stored, "hex");
+  }
+  mkdirSync(memoryDir, { recursive: true });
+  const key = randomBytes(32);
+  writeFileSync(keyPath, key.toString("hex") + "\n", { encoding: "utf8", mode: 0o600 });
+  try { chmodSync(keyPath, 0o600); } catch {}
+  return key;
+}
+
+function deriveKey(master: Buffer, salt: Buffer): Buffer {
+  return scryptSync(master, salt, 32);
+}
+
+function encrypt(memoryDir: string, client: string, division: string, entries: MemoryEntry[]): EnclaveEnvelope {
+  const salt = randomBytes(16);
+  const iv = randomBytes(12);
+  const key = deriveKey(loadMasterKey(memoryDir), salt);
+  const cipher = createCipheriv("aes-256-gcm", key, iv);
+  const ciphertext = Buffer.concat([cipher.update(JSON.stringify(entries), "utf8"), cipher.final()]);
+  return {
+    version: VERSION,
+    client,
+    division,
+    salt: salt.toString("base64"),
+    iv: iv.toString("base64"),
+    tag: cipher.getAuthTag().toString("base64"),
+    ciphertext: ciphertext.toString("base64"),
+  };
+}
+
+function decrypt(memoryDir: string, envelope: EnclaveEnvelope): MemoryEntry[] {
+  if (envelope.version !== VERSION) throw new Error(`Unsupported enclave version ${envelope.version}`);
+  const key = deriveKey(loadMasterKey(memoryDir), Buffer.from(envelope.salt, "base64"));
+  const decipher = createDecipheriv("aes-256-gcm", key, Buffer.from(envelope.iv, "base64"));
+  decipher.setAuthTag(Buffer.from(envelope.tag, "base64"));
+  const plaintext = Buffer.concat([decipher.update(Buffer.from(envelope.ciphertext, "base64")), decipher.final()]);
+  return JSON.parse(plaintext.toString("utf8")) as MemoryEntry[];
+}
+
+function writeEnvelope(path: string, envelope: EnclaveEnvelope): void {
+  mkdirSync(join(path, ".."), { recursive: true });
+  const tmp = `${path}.${process.pid}.tmp`;
+  writeFileSync(tmp, JSON.stringify(envelope, null, 2) + "\n", "utf8");
+  renameSync(tmp, path);
+}
+
+export function createEnclave(memoryDir: string, client: string, division: string = "default"): void {
+  const path = enclavePath(memoryDir, client, division);
+  if (existsSync(path)) return;
+  writeEnvelope(path, encrypt(memoryDir, client, division, []));
+}
+
+export function listEnclaveEntries(memoryDir: string, client: string, division: string = "default"): MemoryEntry[] {
+  const path = enclavePath(memoryDir, client, division);
+  if (!existsSync(path)) return [];
+  const envelope = JSON.parse(readFileSync(path, "utf8")) as EnclaveEnvelope;
+  return decrypt(memoryDir, envelope);
+}
+
+export function putEnclaveEntry(
+  memoryDir: string,
+  client: string,
+  entry: MemoryEntry,
+  division: string = "default",
+): MemoryEntry[] {
+  const entries = listEnclaveEntries(memoryDir, client, division).filter((candidate) => candidate.id !== entry.id);
+  entries.push(entry);
+  writeEnvelope(enclavePath(memoryDir, client, division), encrypt(memoryDir, client, division, entries));
+  return entries;
+}
+
+export function getEnclaveEntry(
+  memoryDir: string,
+  client: string,
+  id: string,
+  division: string = "default",
+): MemoryEntry | null {
+  return listEnclaveEntries(memoryDir, client, division).find((entry) => entry.id === id) ?? null;
+}
diff --git a/test/enclaves.test.ts b/test/enclaves.test.ts
new file mode 100644
index 0000000..4b670f3
--- /dev/null
+++ b/test/enclaves.test.ts
@@ -0,0 +1,49 @@
+import { describe, test, expect } from "bun:test";
+import { existsSync, mkdtempSync, readFileSync, rmSync, statSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { createEnclave, listEnclaveEntries, putEnclaveEntry, getEnclaveEntry } from "../src/store/enclaves.ts";
+import type { MemoryEntry } from "../src/types.ts";
+
+function entry(id: string, content: string): MemoryEntry {
+  const now = new Date().toISOString();
+  return { id, title: content, content, project: "client-a", status: "confirmed", created_at: now, updated_at: now, tags: [] } as MemoryEntry;
+}
+
+describe("T-437: encrypted client enclaves", () => {
+  test("round-trips per client/division and stores no plaintext", () => {
+    const memoryDir = mkdtempSync(join(tmpdir(), "muse-enclave-"));
+    try {
+      createEnclave(memoryDir, "client-a");
+      putEnclaveEntry(memoryDir, "client-a", entry("m_1_secret", "super secret credential plan"));
+      expect(getEnclaveEntry(memoryDir, "client-a", "m_1_secret")?.content).toBe("super secret credential plan");
+
+      const file = join(memoryDir, "enclaves", "client-a", "default.enc.json");
+      expect(readFileSync(file, "utf8")).not.toContain("super secret");
+      expect(statSync(join(memoryDir, "enclave.key")).mode & 0o077).toBe(0);
+
+      expect(listEnclaveEntries(memoryDir, "client-b")).toEqual([]);
+      putEnclaveEntry(memoryDir, "client-b", entry("m_2_other", "client b only"));
+      expect(listEnclaveEntries(memoryDir, "client-a").map((e) => e.id)).toEqual(["m_1_secret"]);
+      expect(listEnclaveEntries(memoryDir, "client-b").map((e) => e.id)).toEqual(["m_2_other"]);
+    } finally {
+      rmSync(memoryDir, { recursive: true, force: true });
+    }
+  });
+
+  test("tampered ciphertext fails authentication", () => {
+    const memoryDir = mkdtempSync(join(tmpdir(), "muse-enclave-tamper-"));
+    try {
+      createEnclave(memoryDir, "client-a");
+      putEnclaveEntry(memoryDir, "client-a", entry("m_1_secret", "secret"));
+      const file = join(memoryDir, "enclaves", "client-a", "default.enc.json");
+      const envelope = JSON.parse(readFileSync(file, "utf8"));
+      envelope.ciphertext = Buffer.from("tampered").toString("base64");
+      writeFileSync(file, JSON.stringify(envelope));
+      expect(() => listEnclaveEntries(memoryDir, "client-a")).toThrow();
+      expect(existsSync(file)).toBe(true);
+    } finally {
+      rmSync(memoryDir, { recursive: true, force: true });
+    }
+  });
+});