diff --git a/.changeset/auth-durable-secret-store.md b/.changeset/auth-durable-secret-store.md
new file mode 100644
index 0000000..3d35056
--- /dev/null
+++ b/.changeset/auth-durable-secret-store.md
@@ -0,0 +1,17 @@
+---
+'@enbox/gitd': minor
+---
+
+feat: durable vault-unlock secret so commands stop re-prompting
+
+gitd now resolves the vault unlock password through a single path (explicit →
+`GITD_PASSWORD` → public-reader secret → durable secret store → prompt) and
+persists a freshly entered secret in a durable per-profile store — the OS
+keychain (macOS `security`, Linux `secret-tool`) when available, otherwise a
+machine-keyed AES-256-GCM encrypted file under `~/.enbox/secrets/`. After the
+first unlock, subsequent commands restore the session without prompting for the
+vault password again.
+
+`GITD_SECRET_BACKEND=keychain|file|none` pins or disables the backend. A cached
+secret that is later rejected is cleared automatically so a stale secret can't
+lock you out. `gitd auth logout` / `gitd auth reset` drop the stored secret.
diff --git a/src/auth/secret-store.ts b/src/auth/secret-store.ts
new file mode 100644
index 0000000..0d02991
--- /dev/null
+++ b/src/auth/secret-store.ts
@@ -0,0 +1,295 @@
+/**
+ * Durable per-profile secret store for gitd vault-unlock secrets.
+ *
+ * gitd unlocks a profile's Enbox vault with a secret. Persisting that secret
+ * durably lets the CLI and the credential helper restore a session without
+ * re-prompting on every command — the root cause of "asked for the vault
+ * password repeatedly".
+ *
+ * Backends, in preference order:
+ *   1. OS keychain — macOS `security`, Linux `secret-tool` (libsecret).
+ *   2. Encrypted file — AES-256-GCM under `~/.enbox/secrets/<profile>.enc`,
+ *      keyed by a machine + user derived key, file mode 0600.
+ *
+ * The active backend can be pinned with `GITD_SECRET_BACKEND`:
+ *   - `keychain` — OS keychain only (no file fallback).
+ *   - `file`     — encrypted file only (skip the keychain).
+ *   - `none`     — disable durable storage entirely (CI / ephemeral use).
+ * When unset, gitd prefers the keychain and falls back to the encrypted file.
+ *
+ * @module
+ */
+
+import { execFileSync } from 'node:child_process';
+import { join } from 'node:path';
+import { createCipheriv, createDecipheriv, createHash, randomBytes } from 'node:crypto';
+import { existsSync, mkdirSync, readFileSync, rmSync, writeFileSync } from 'node:fs';
+import { hostname, userInfo } from 'node:os';
+
+import { enboxHome } from '../profiles/config.js';
+
+// ---------------------------------------------------------------------------
+// Constants
+// ---------------------------------------------------------------------------
+
+/** Keychain service name used for all gitd secrets. */
+const SERVICE = 'gitd';
+
+/** Timeout for keychain CLI invocations. */
+const KEYCHAIN_TIMEOUT_MS = 5_000;
+
+/** Selectable backends. `undefined` means auto (keychain, then file). */
+type Backend = 'keychain' | 'file' | 'none';
+
+// ---------------------------------------------------------------------------
+// Public API
+// ---------------------------------------------------------------------------
+
+/** Retrieve the stored vault secret for a profile, or `undefined` if none. */
+export async function getVaultSecret(profileName: string): Promise<string | undefined> {
+  const backend = configuredBackend();
+  if (backend === 'none') { return undefined; }
+
+  if (backend !== 'file' && keychainSupported()) {
+    const value = keychainGet(profileName);
+    if (value !== undefined) { return value; }
+    if (backend === 'keychain') { return undefined; }
+  }
+
+  return fileGet(profileName);
+}
+
+/** Persist the vault secret for a profile durably. */
+export async function setVaultSecret(profileName: string, secret: string): Promise<void> {
+  const backend = configuredBackend();
+  if (backend === 'none') { return; }
+
+  if (backend !== 'file' && keychainSupported()) {
+    if (keychainSet(profileName, secret)) {
+      // Clear any stale file copy so reads stay consistent with the keychain.
+      fileDelete(profileName);
+      return;
+    }
+    if (backend === 'keychain') {
+      throw new Error('GITD_SECRET_BACKEND=keychain but the OS keychain is unavailable.');
+    }
+  }
+
+  fileSet(profileName, secret);
+}
+
+/** Remove the stored vault secret for a profile from all backends. */
+export async function deleteVaultSecret(profileName: string): Promise<void> {
+  const backend = configuredBackend();
+  if (backend === 'none') { return; }
+
+  if (backend !== 'file' && keychainSupported()) {
+    keychainDelete(profileName);
+  }
+  fileDelete(profileName);
+}
+
+/** Describe the active backend for diagnostics (`gitd doctor`, status). */
+export function describeSecretBackend(): string {
+  const backend = configuredBackend();
+  if (backend === 'none') { return 'disabled (GITD_SECRET_BACKEND=none)'; }
+  if (backend === 'file') { return 'encrypted file'; }
+  if (backend === 'keychain') { return 'OS keychain'; }
+  return keychainSupported() ? 'OS keychain (encrypted file fallback)' : 'encrypted file';
+}
+
+// ---------------------------------------------------------------------------
+// Backend selection
+// ---------------------------------------------------------------------------
+
+function configuredBackend(): Backend | undefined {
+  const value = process.env.GITD_SECRET_BACKEND?.toLowerCase();
+  if (value === 'keychain' || value === 'file' || value === 'none') { return value; }
+  return undefined;
+}
+
+function keychainSupported(): boolean {
+  return process.platform === 'darwin' || process.platform === 'linux';
+}
+
+/** Keychain account label for a profile. */
+function account(profileName: string): string {
+  return `vault:${profileName}`;
+}
+
+// ---------------------------------------------------------------------------
+// OS keychain backend
+// ---------------------------------------------------------------------------
+
+function keychainGet(profileName: string): string | undefined {
+  try {
+    if (process.platform === 'darwin') {
+      const out = execFileSync(
+        'security',
+        ['find-generic-password', '-s', SERVICE, '-a', account(profileName), '-w'],
+        { encoding: 'utf-8', stdio: ['ignore', 'pipe', 'ignore'], timeout: KEYCHAIN_TIMEOUT_MS },
+      );
+      const value = out.replace(/\n$/, '');
+      return value.length > 0 ? value : undefined;
+    }
+    if (process.platform === 'linux') {
+      const out = execFileSync(
+        'secret-tool',
+        ['lookup', 'service', SERVICE, 'account', account(profileName)],
+        { encoding: 'utf-8', stdio: ['ignore', 'pipe', 'ignore'], timeout: KEYCHAIN_TIMEOUT_MS },
+      );
+      return out.length > 0 ? out : undefined;
+    }
+  } catch {
+    // Not found, no keyring, or tool missing — fall back to the file backend.
+  }
+  return undefined;
+}
+
+function keychainSet(profileName: string, secret: string): boolean {
+  try {
+    if (process.platform === 'darwin') {
+      execFileSync(
+        'security',
+        ['add-generic-password', '-U', '-s', SERVICE, '-a', account(profileName), '-w', secret],
+        { stdio: 'ignore', timeout: KEYCHAIN_TIMEOUT_MS },
+      );
+      return true;
+    }
+    if (process.platform === 'linux') {
+      execFileSync(
+        'secret-tool',
+        ['store', '--label', `gitd ${profileName}`, 'service', SERVICE, 'account', account(profileName)],
+        { input: secret, stdio: ['pipe', 'ignore', 'ignore'], timeout: KEYCHAIN_TIMEOUT_MS },
+      );
+      return true;
+    }
+  } catch {
+    // Keyring locked / tool missing — caller falls back to the file backend.
+  }
+  return false;
+}
+
+function keychainDelete(profileName: string): void {
+  try {
+    if (process.platform === 'darwin') {
+      execFileSync(
+        'security',
+        ['delete-generic-password', '-s', SERVICE, '-a', account(profileName)],
+        { stdio: 'ignore', timeout: KEYCHAIN_TIMEOUT_MS },
+      );
+    } else if (process.platform === 'linux') {
+      execFileSync(
+        'secret-tool',
+        ['clear', 'service', SERVICE, 'account', account(profileName)],
+        { stdio: 'ignore', timeout: KEYCHAIN_TIMEOUT_MS },
+      );
+    }
+  } catch {
+    // Nothing to delete, or no keyring — safe to ignore.
+  }
+}
+
+// ---------------------------------------------------------------------------
+// Encrypted file backend
+// ---------------------------------------------------------------------------
+
+/** Stored ciphertext envelope. */
+type SecretFile = {
+  v : 1;
+  iv : string;
+  tag : string;
+  ct : string;
+};
+
+function secretsDir(): string {
+  return join(enboxHome(), 'secrets');
+}
+
+function secretFilePath(profileName: string): string {
+  const safe = profileName.replace(/[^a-zA-Z0-9_-]/g, '_');
+  return join(secretsDir(), `${safe}.enc`);
+}
+
+function fileGet(profileName: string): string | undefined {
+  const path = secretFilePath(profileName);
+  if (!existsSync(path)) { return undefined; }
+  try {
+    const envelope = JSON.parse(readFileSync(path, 'utf-8')) as SecretFile;
+    const decipher = createDecipheriv('aes-256-gcm', fileKey(), Buffer.from(envelope.iv, 'hex'));
+    decipher.setAuthTag(Buffer.from(envelope.tag, 'hex'));
+    const plain = Buffer.concat([decipher.update(Buffer.from(envelope.ct, 'hex')), decipher.final()]);
+    return plain.toString('utf-8');
+  } catch {
+    // Corrupt, tampered, or written by another machine/user — treat as absent.
+    return undefined;
+  }
+}
+
+function fileSet(profileName: string, secret: string): void {
+  mkdirSync(secretsDir(), { recursive: true, mode: 0o700 });
+  const iv = randomBytes(12);
+  const cipher = createCipheriv('aes-256-gcm', fileKey(), iv);
+  const ct = Buffer.concat([cipher.update(Buffer.from(secret, 'utf-8')), cipher.final()]);
+  const envelope: SecretFile = {
+    v   : 1,
+    iv  : iv.toString('hex'),
+    tag : cipher.getAuthTag().toString('hex'),
+    ct  : ct.toString('hex'),
+  };
+  writeFileSync(secretFilePath(profileName), JSON.stringify(envelope), { mode: 0o600 });
+}
+
+function fileDelete(profileName: string): void {
+  const path = secretFilePath(profileName);
+  if (existsSync(path)) { rmSync(path, { force: true }); }
+}
+
+/**
+ * Derive the 32-byte AES key for the encrypted-file backend.
+ *
+ * The key is bound to this machine and user: a stable machine id plus the
+ * username, mixed with a per-install random key persisted under the secrets
+ * directory. Copying the `.enc` file to another machine or user will not
+ * decrypt it.
+ */
+function fileKey(): Buffer {
+  mkdirSync(secretsDir(), { recursive: true, mode: 0o700 });
+  const keyPath = join(secretsDir(), '.machine-key');
+  let base: Buffer;
+  if (existsSync(keyPath)) {
+    base = readFileSync(keyPath);
+  } else {
+    base = randomBytes(32);
+    writeFileSync(keyPath, base, { mode: 0o600 });
+  }
+  return createHash('sha256')
+    .update(base)
+    .update(machineId())
+    .update(userInfo().username)
+    .digest();
+}
+
+/** Best-effort stable machine identifier, falling back to the hostname. */
+function machineId(): string {
+  try {
+    if (process.platform === 'linux') {
+      for (const path of ['/etc/machine-id', '/var/lib/dbus/machine-id']) {
+        if (existsSync(path)) { return readFileSync(path, 'utf-8').trim(); }
+      }
+    } else if (process.platform === 'darwin') {
+      const out = execFileSync('ioreg', ['-rd1', '-c', 'IOPlatformExpertDevice'], {
+        encoding : 'utf-8',
+        stdio    : ['ignore', 'pipe', 'ignore'],
+        timeout  : 2_000,
+      });
+      const match = out.match(/"IOPlatformUUID"\s*=\s*"([^"]+)"/);
+      if (match) { return match[1]; }
+    } else if (process.platform === 'win32') {
+      return process.env.COMPUTERNAME ?? hostname();
+    }
+  } catch {
+    // Fall through to the hostname.
+  }
+  return hostname();
+}
diff --git a/src/auth/vault-password.ts b/src/auth/vault-password.ts
new file mode 100644
index 0000000..66a61af
--- /dev/null
+++ b/src/auth/vault-password.ts
@@ -0,0 +1,158 @@
+/**
+ * Vault-password resolution and durable caching.
+ *
+ * One place that answers "what unlocks this profile's vault?", consulting, in
+ * order: an explicit value, `GITD_PASSWORD`, the hidden public-reader secret,
+ * the durable secret store (OS keychain / encrypted file), and finally an
+ * interactive prompt. The resolved source is tracked so a freshly entered
+ * secret can be cached for next time — turning the previously per-command
+ * password prompt into a one-time event.
+ *
+ * @module
+ */
+
+import { readPublicReaderPasswordForActiveProfile } from '../profiles/public-reader.js';
+
+import { deleteVaultSecret, getVaultSecret, setVaultSecret } from './secret-store.js';
+
+// ---------------------------------------------------------------------------
+// Types
+// ---------------------------------------------------------------------------
+
+/** Where a resolved password came from. */
+export type PasswordSource = 'explicit' | 'env' | 'public-reader' | 'keychain' | 'tty';
+
+/** A resolved vault password together with its origin. */
+export type ResolvedPassword = {
+  password : string;
+  source : PasswordSource;
+};
+
+/** Options for {@link resolveVaultPassword}. */
+export type ResolveVaultPasswordOptions = {
+  /** Active profile name (used for public-reader + durable secret lookup). */
+  profileName? : string;
+  /** Caller-supplied password (e.g. from a first-run wizard); wins outright. */
+  explicit? : string;
+  /** Environment to read `GITD_PASSWORD` from. Defaults to `process.env`. */
+  env? : NodeJS.ProcessEnv;
+  /** Whether to fall back to an interactive prompt. Defaults to `true`. */
+  allowPrompt? : boolean;
+  /** Prompt label shown when reading interactively. */
+  promptMessage? : string;
+};
+
+// ---------------------------------------------------------------------------
+// Resolution
+// ---------------------------------------------------------------------------
+
+/**
+ * Resolve the vault password for a profile.
+ *
+ * Precedence: explicit → `GITD_PASSWORD` → public-reader secret → durable
+ * secret store → interactive prompt.
+ *
+ * @throws If no password is available and prompting is disabled.
+ */
+export async function resolveVaultPassword(options: ResolveVaultPasswordOptions): Promise<ResolvedPassword> {
+  const { profileName, explicit, env = process.env, allowPrompt = true, promptMessage } = options;
+
+  if (explicit) { return { password: explicit, source: 'explicit' }; }
+
+  const envPassword = env.GITD_PASSWORD;
+  if (envPassword) { return { password: envPassword, source: 'env' }; }
+
+  const publicReaderPassword = readPublicReaderPasswordForActiveProfile(profileName);
+  if (publicReaderPassword) { return { password: publicReaderPassword, source: 'public-reader' }; }
+
+  if (profileName) {
+    const cached = await getVaultSecret(profileName);
+    if (cached) { return { password: cached, source: 'keychain' }; }
+  }
+
+  if (!allowPrompt) {
+    throw new Error('No vault password available. Set GITD_PASSWORD or run `gitd auth login`.');
+  }
+
+  const password = await promptVaultPassword(promptMessage);
+  return { password, source: 'tty' };
+}
+
+/**
+ * Persist a freshly entered secret so later commands restore without a prompt.
+ *
+ * Only `tty` and `explicit` (first-run) secrets are cached. `env` secrets are
+ * left ephemeral by design, and `keychain` / `public-reader` secrets are
+ * already durable.
+ */
+export async function rememberVaultSecret(profileName: string | undefined, resolved: ResolvedPassword): Promise<void> {
+  if (!profileName) { return; }
+  if (resolved.source !== 'tty' && resolved.source !== 'explicit') { return; }
+  try {
+    await setVaultSecret(profileName, resolved.password);
+  } catch (err) {
+    // Caching is an optimization — never fail the command over it.
+    console.error(`[auth] Could not cache unlock secret: ${(err as Error).message}`);
+  }
+}
+
+/** Drop a profile's durable secret (logout, reset, or rejected-secret repair). */
+export async function forgetVaultSecret(profileName: string): Promise<void> {
+  await deleteVaultSecret(profileName);
+}
+
+// ---------------------------------------------------------------------------
+// Interactive prompt
+// ---------------------------------------------------------------------------
+
+/**
+ * Prompt for a vault password.
+ *
+ * On a TTY the input is read in raw mode with no echo; otherwise the password
+ * is read from piped stdin. Ctrl-C aborts with exit code 130.
+ */
+export async function promptVaultPassword(message = 'Identity password: '): Promise<string> {
+  process.stdout.write(message);
+
+  if (process.stdin.isTTY) {
+    return new Promise<string>((resolve) => {
+      let buf = '';
+      process.stdin.setRawMode(true);
+      process.stdin.setEncoding('utf8');
+      process.stdin.resume();
+
+      const onData = (ch: string): void => {
+        const code = ch.charCodeAt(0);
+
+        if (ch === '\r' || ch === '\n') {
+          process.stdin.setRawMode(false);
+          process.stdin.pause();
+          process.stdin.removeListener('data', onData);
+          process.stdout.write('\n');
+          resolve(buf);
+        } else if (code === 3) {
+          process.stdin.setRawMode(false);
+          process.stdout.write('\n');
+          process.exit(130);
+        } else if (code === 127 || code === 8) {
+          if (buf.length > 0) { buf = buf.slice(0, -1); }
+        } else if (code >= 32) {
+          buf += ch;
+        }
+      };
+
+      process.stdin.on('data', onData);
+    });
+  }
+
+  // Non-TTY fallback (piped input).
+  return new Promise<string>((resolve) => {
+    let buf = '';
+    process.stdin.setEncoding('utf8');
+    process.stdin.once('data', (chunk: string) => {
+      buf += chunk;
+      resolve(buf.trim());
+    });
+    process.stdin.resume();
+  });
+}
diff --git a/src/cli/commands/auth.ts b/src/cli/commands/auth.ts
index 402ad0c..337d614 100644
--- a/src/cli/commands/auth.ts
+++ b/src/cli/commands/auth.ts
@@ -39,6 +39,7 @@ import {
   upsertProfile,
   writeConfig,
 } from '../../profiles/config.js';
+import { forgetVaultSecret, rememberVaultSecret } from '../../auth/vault-password.js';
 
 const DEFAULT_IDENTITY_NAME = 'default';
 
@@ -290,6 +291,9 @@ async function authLogin(): Promise<void> {
       createdAt : new Date().toISOString(),
     });
 
+    // Persist the unlock secret so later commands restore without a prompt.
+    await rememberVaultSecret(profileName, { password: password as string, source: 'explicit' });
+
     spin.stop('Identity created!');
 
     p.log.success(`DID:      ${result.did}`);
@@ -484,6 +488,7 @@ async function authReset(args: string[]): Promise<void> {
 
   try {
     const result = resetIdentityLocally(name);
+    await forgetVaultSecret(name);
     p.log.success(`Identity "${result.name}" reset.`);
     if (result.backupPath) {
       p.log.info(`Backup: ${result.backupPath}`);
@@ -572,6 +577,7 @@ async function authLogout(args: string[]): Promise<void> {
     config.defaultProfile = remaining[0] ?? '';
   }
   writeConfig(config);
+  await forgetVaultSecret(name);
 
   p.log.success(`Identity "${name}" removed.`);
   p.log.info(`Data directory preserved at: ${profileDataPath(name)}`);
diff --git a/src/cli/identity-wizard.ts b/src/cli/identity-wizard.ts
index f128079..9d5c576 100644
--- a/src/cli/identity-wizard.ts
+++ b/src/cli/identity-wizard.ts
@@ -12,6 +12,7 @@ import * as p from '@clack/prompts';
 
 import { connectAgent } from './agent.js';
 import { flagValue } from './flags.js';
+import { rememberVaultSecret } from '../auth/vault-password.js';
 import { listProfiles, profileDataPath } from '../profiles/config.js';
 import {
   normalizeIdentityNameInput,
@@ -194,6 +195,9 @@ export async function createFirstIdentityFromSetup(setup: FirstIdentitySetup): P
     sync           : 'off',
   });
 
+  // Persist the unlock secret so later commands restore without a prompt.
+  await rememberVaultSecret(setup.profileName, { password: setup.password, source: 'explicit' });
+
   try {
     const recordedProfile = recordConnectedProfile(setup.profileName, ctx.did);
     if (recordedProfile.created && ctx.recoveryPhrase) {
diff --git a/src/cli/main.ts b/src/cli/main.ts
index 8acc3ee..d5e04ac 100644
--- a/src/cli/main.ts
+++ b/src/cli/main.ts
@@ -90,6 +90,7 @@ import { spawn } from 'node:child_process';
 import { dirname, join } from 'node:path';
 
 import type { FirstIdentitySetup } from './identity-wizard.js';
+import type { ResolvedPassword } from '../auth/vault-password.js';
 
 import { authCommand } from './commands/auth.js';
 import { cloneCommand } from './commands/clone.js';
@@ -98,12 +99,12 @@ import { dispatchAgentCommand } from './dispatch.js';
 import { doctorCommand } from './commands/doctor.js';
 import { flagValue } from './flags.js';
 import { forwardCliCommandIfAvailable } from './local-rpc.js';
-import { readPublicReaderPasswordForActiveProfile } from '../profiles/public-reader.js';
 import { repairCommand } from './commands/repair.js';
 import { setupCommand } from './commands/setup.js';
 import { checkGit, requireGit, warnGit } from './preflight.js';
 import { createFirstIdentityFromSetup, maybePromptForFirstIdentitySetup } from './identity-wizard.js';
 import { ensureDaemon, findGitdBin, markDeferredDaemonStart } from '../daemon/lifecycle.js';
+import { forgetVaultSecret, rememberVaultSecret, resolveVaultPassword } from '../auth/vault-password.js';
 import { helperCommand, serveDaemonCommand } from './commands/serve-lifecycle.js';
 import { printImplicitRecoveryPhrase, recordConnectedProfile, resolveCommandProfile } from './profile-session.js';
 import { publicReaderWriteBlockMessage, shouldBlockPublicReaderCommand } from './public-reader-guard.js';
@@ -282,67 +283,18 @@ function printUsage(): void {
 // Password
 // ---------------------------------------------------------------------------
 
-async function getPassword(): Promise<string> {
-  // Prefer env var for non-interactive use / testing.
-  const env = process.env.GITD_PASSWORD;
-  if (env) { return env; }
-
-  const publicReaderPassword = readPublicReaderPasswordForActiveProfile();
-  if (publicReaderPassword) { return publicReaderPassword; }
-
-  // Interactive prompt — hide input when running in a TTY.
-  process.stdout.write('Identity password: ');
-
-  if (process.stdin.isTTY) {
-    // Raw mode: read character-by-character, echo nothing.
-    const password = await new Promise<string>((resolve) => {
-      let buf = '';
-      process.stdin.setRawMode(true);
-      process.stdin.setEncoding('utf8');
-      process.stdin.resume();
-
-      const onData = (ch: string): void => {
-        const code = ch.charCodeAt(0);
-
-        if (ch === '\r' || ch === '\n') {
-          // Enter — done.
-          process.stdin.setRawMode(false);
-          process.stdin.pause();
-          process.stdin.removeListener('data', onData);
-          process.stdout.write('\n');
-          resolve(buf);
-        } else if (code === 3) {
-          // Ctrl-C — abort.
-          process.stdin.setRawMode(false);
-          process.stdout.write('\n');
-          process.exit(130);
-        } else if (code === 127 || code === 8) {
-          // Backspace / Delete.
-          if (buf.length > 0) {
-            buf = buf.slice(0, -1);
-          }
-        } else if (code >= 32) {
-          // Printable character.
-          buf += ch;
-        }
-      };
-
-      process.stdin.on('data', onData);
-    });
-    return password;
-  }
-
-  // Non-TTY fallback (piped input).
-  const response = await new Promise<string>((resolve) => {
-    let buf = '';
-    process.stdin.setEncoding('utf8');
-    process.stdin.once('data', (chunk: string) => {
-      buf += chunk;
-      resolve(buf.trim());
-    });
-    process.stdin.resume();
-  });
-  return response;
+/**
+ * Resolve the vault password for a command and, on a verified unlock, cache a
+ * freshly entered secret so later commands don't re-prompt.
+ *
+ * Resolution and caching live in `../auth/vault-password.js`; this wrapper
+ * keeps the call sites terse while threading the active profile name through.
+ */
+async function resolveCommandPassword(
+  profileName: string | undefined,
+  explicit?: string,
+): Promise<ResolvedPassword> {
+  return resolveVaultPassword({ profileName, explicit });
 }
 
 async function maybeDelayHelperStart(args: string[]): Promise<void> {
@@ -489,7 +441,6 @@ async function main(): Promise<void> {
         if (setup) {
           await createFirstIdentityFromSetup(setup);
         }
-        const pw = setup?.password ?? await getPassword();
         let profileName: string | undefined;
         try {
           profileName = setup?.profileName ?? resolveCommandProfile(flagValue(rest, '--profile')).name;
@@ -497,12 +448,17 @@ async function main(): Promise<void> {
           console.error(`gitd: ${(err as Error).message}`);
           process.exit(1);
         }
+        const resolved = await resolveCommandPassword(profileName, setup?.password);
         try {
-          const result = await ensureDaemon(pw, { profileName });
+          const result = await ensureDaemon(resolved.password, { profileName });
+          await rememberVaultSecret(profileName, resolved);
           for (const line of serveLocalHelperAliasLines(result.spawned, result.port)) {
             console.log(line);
           }
         } catch (err) {
+          if (resolved.source === 'keychain' && profileName) {
+            await forgetVaultSecret(profileName);
+          }
           console.error(`Failed to start local helper: ${(err as Error).message}`);
           process.exit(1);
         }
@@ -559,14 +515,24 @@ async function main(): Promise<void> {
   }
 
   // Commands that require the Enbox agent.
-  const password = firstIdentitySetup?.password ?? await getPassword();
+  const resolved = await resolveCommandPassword(profileName, firstIdentitySetup?.password);
 
-  const ctx = await connectAgentWithRetry({
-    password,
-    dataPath       : commandProfile.dataPath,
-    sync           : sync as any,
-    recoveryPhrase : firstIdentitySetup?.recoveryPhrase,
-  });
+  let ctx: Awaited<ReturnType<typeof connectAgentWithRetry>>;
+  try {
+    ctx = await connectAgentWithRetry({
+      password       : resolved.password,
+      dataPath       : commandProfile.dataPath,
+      sync           : sync as any,
+      recoveryPhrase : firstIdentitySetup?.recoveryPhrase,
+    });
+  } catch (err) {
+    if (resolved.source === 'keychain' && profileName) {
+      await forgetVaultSecret(profileName);
+      console.error('gitd: the cached unlock secret was rejected and cleared. Re-run the command to re-enter it.');
+    }
+    throw err;
+  }
+  await rememberVaultSecret(profileName, resolved);
   const recordedProfile = recordConnectedProfile(profileName, ctx.did);
   ctx.profileName = profileName;
 
@@ -599,9 +565,9 @@ async function main(): Promise<void> {
   // `gitd init` without hiding first-run recovery phrase output in the helper.
   if (completed && !longRunning && shouldAutoStartHelperAfterCommand(command, rest)) {
     try {
-      await ensureDaemon(password, { profileName: profileName ?? undefined });
+      await ensureDaemon(resolved.password, { profileName: profileName ?? undefined });
     } catch (err) {
-      if (isTransientHelperLockError(err) && scheduleDeferredHelperStart(password, profileName ?? undefined)) {
+      if (isTransientHelperLockError(err) && scheduleDeferredHelperStart(resolved.password, profileName ?? undefined)) {
         process.exit(0);
       }
       // Non-fatal — warn but don't block the command.
diff --git a/tests/secret-store.spec.ts b/tests/secret-store.spec.ts
new file mode 100644
index 0000000..da956b3
--- /dev/null
+++ b/tests/secret-store.spec.ts
@@ -0,0 +1,86 @@
+/**
+ * Durable secret-store tests.
+ *
+ * Pins the encrypted-file backend (`GITD_SECRET_BACKEND=file`) and an isolated
+ * `ENBOX_HOME` so the real OS keychain is never touched.
+ */
+import { afterEach, beforeEach, describe, expect, it } from 'bun:test';
+
+import { join } from 'node:path';
+import { tmpdir } from 'node:os';
+import { existsSync, mkdtempSync, readFileSync, rmSync } from 'node:fs';
+
+import { enboxHome } from '../src/profiles/config.js';
+import { deleteVaultSecret, getVaultSecret, setVaultSecret } from '../src/auth/secret-store.js';
+
+let tempDir: string;
+let originalEnboxHome: string | undefined;
+let originalBackend: string | undefined;
+
+function secretFile(profile: string): string {
+  return join(enboxHome(), 'secrets', `${profile}.enc`);
+}
+
+describe('secret store (encrypted file backend)', () => {
+  beforeEach(() => {
+    originalEnboxHome = process.env.ENBOX_HOME;
+    originalBackend = process.env.GITD_SECRET_BACKEND;
+    tempDir = mkdtempSync(join(tmpdir(), 'gitd-secret-store-'));
+    process.env.ENBOX_HOME = join(tempDir, 'enbox');
+    process.env.GITD_SECRET_BACKEND = 'file';
+  });
+
+  afterEach(() => {
+    if (originalEnboxHome) { process.env.ENBOX_HOME = originalEnboxHome; } else { delete process.env.ENBOX_HOME; }
+    if (originalBackend) { process.env.GITD_SECRET_BACKEND = originalBackend; } else { delete process.env.GITD_SECRET_BACKEND; }
+    rmSync(tempDir, { recursive: true, force: true });
+  });
+
+  it('returns undefined when nothing is stored', async () => {
+    expect(await getVaultSecret('default')).toBeUndefined();
+  });
+
+  it('round-trips a stored secret', async () => {
+    await setVaultSecret('default', 'hunter2');
+    expect(await getVaultSecret('default')).toBe('hunter2');
+  });
+
+  it('stores the secret encrypted at rest (not plaintext)', async () => {
+    await setVaultSecret('default', 'super-secret-phrase');
+    const path = secretFile('default');
+    expect(existsSync(path)).toBe(true);
+    const raw = readFileSync(path, 'utf-8');
+    expect(raw).not.toContain('super-secret-phrase');
+    const envelope = JSON.parse(raw) as { v: number; iv: string; tag: string; ct: string };
+    expect(envelope.v).toBe(1);
+    expect(envelope.iv.length).toBeGreaterThan(0);
+    expect(envelope.tag.length).toBeGreaterThan(0);
+    expect(envelope.ct.length).toBeGreaterThan(0);
+  });
+
+  it('overwrites an existing secret', async () => {
+    await setVaultSecret('default', 'first');
+    await setVaultSecret('default', 'second');
+    expect(await getVaultSecret('default')).toBe('second');
+  });
+
+  it('isolates secrets per profile', async () => {
+    await setVaultSecret('work', 'work-pw');
+    await setVaultSecret('personal', 'personal-pw');
+    expect(await getVaultSecret('work')).toBe('work-pw');
+    expect(await getVaultSecret('personal')).toBe('personal-pw');
+  });
+
+  it('deletes a stored secret', async () => {
+    await setVaultSecret('default', 'hunter2');
+    await deleteVaultSecret('default');
+    expect(await getVaultSecret('default')).toBeUndefined();
+    expect(existsSync(secretFile('default'))).toBe(false);
+  });
+
+  it('is a no-op when the backend is disabled', async () => {
+    process.env.GITD_SECRET_BACKEND = 'none';
+    await setVaultSecret('default', 'hunter2');
+    expect(await getVaultSecret('default')).toBeUndefined();
+  });
+});
diff --git a/tests/vault-password.spec.ts b/tests/vault-password.spec.ts
new file mode 100644
index 0000000..d6040ed
--- /dev/null
+++ b/tests/vault-password.spec.ts
@@ -0,0 +1,111 @@
+/**
+ * Vault-password resolution + durable caching tests.
+ *
+ * Pins the encrypted-file secret backend and an isolated `ENBOX_HOME`.
+ * Prompting is disabled (`allowPrompt: false`) so resolution is deterministic.
+ */
+import { afterEach, beforeEach, describe, expect, it } from 'bun:test';
+
+import { join } from 'node:path';
+import { tmpdir } from 'node:os';
+import { mkdtempSync, rmSync } from 'node:fs';
+
+import { forgetVaultSecret, rememberVaultSecret, resolveVaultPassword } from '../src/auth/vault-password.js';
+import { getVaultSecret, setVaultSecret } from '../src/auth/secret-store.js';
+
+let tempDir: string;
+let originalEnboxHome: string | undefined;
+let originalBackend: string | undefined;
+let originalPassword: string | undefined;
+
+describe('vault password resolution', () => {
+  beforeEach(() => {
+    originalEnboxHome = process.env.ENBOX_HOME;
+    originalBackend = process.env.GITD_SECRET_BACKEND;
+    originalPassword = process.env.GITD_PASSWORD;
+    tempDir = mkdtempSync(join(tmpdir(), 'gitd-vault-password-'));
+    process.env.ENBOX_HOME = join(tempDir, 'enbox');
+    process.env.GITD_SECRET_BACKEND = 'file';
+    delete process.env.GITD_PASSWORD;
+  });
+
+  afterEach(() => {
+    if (originalEnboxHome) { process.env.ENBOX_HOME = originalEnboxHome; } else { delete process.env.ENBOX_HOME; }
+    if (originalBackend) { process.env.GITD_SECRET_BACKEND = originalBackend; } else { delete process.env.GITD_SECRET_BACKEND; }
+    if (originalPassword) { process.env.GITD_PASSWORD = originalPassword; } else { delete process.env.GITD_PASSWORD; }
+    rmSync(tempDir, { recursive: true, force: true });
+  });
+
+  it('prefers an explicit password', async () => {
+    const resolved = await resolveVaultPassword({ profileName: 'default', explicit: 'explicit-pw', env: {} });
+    expect(resolved).toEqual({ password: 'explicit-pw', source: 'explicit' });
+  });
+
+  it('falls back to GITD_PASSWORD from the environment', async () => {
+    const resolved = await resolveVaultPassword({ profileName: 'default', env: { GITD_PASSWORD: 'env-pw' } });
+    expect(resolved).toEqual({ password: 'env-pw', source: 'env' });
+  });
+
+  it('explicit beats the environment', async () => {
+    const resolved = await resolveVaultPassword({
+      profileName : 'default',
+      explicit    : 'explicit-pw',
+      env         : { GITD_PASSWORD: 'env-pw' },
+    });
+    expect(resolved.source).toBe('explicit');
+  });
+
+  it('reads a cached secret from the durable store', async () => {
+    await setVaultSecret('default', 'cached-pw');
+    const resolved = await resolveVaultPassword({ profileName: 'default', env: {}, allowPrompt: false });
+    expect(resolved).toEqual({ password: 'cached-pw', source: 'keychain' });
+  });
+
+  it('throws when nothing is available and prompting is disabled', async () => {
+    await expect(
+      resolveVaultPassword({ profileName: 'default', env: {}, allowPrompt: false }),
+    ).rejects.toThrow();
+  });
+});
+
+describe('vault secret caching', () => {
+  beforeEach(() => {
+    originalEnboxHome = process.env.ENBOX_HOME;
+    originalBackend = process.env.GITD_SECRET_BACKEND;
+    tempDir = mkdtempSync(join(tmpdir(), 'gitd-vault-cache-'));
+    process.env.ENBOX_HOME = join(tempDir, 'enbox');
+    process.env.GITD_SECRET_BACKEND = 'file';
+  });
+
+  afterEach(() => {
+    if (originalEnboxHome) { process.env.ENBOX_HOME = originalEnboxHome; } else { delete process.env.ENBOX_HOME; }
+    if (originalBackend) { process.env.GITD_SECRET_BACKEND = originalBackend; } else { delete process.env.GITD_SECRET_BACKEND; }
+    rmSync(tempDir, { recursive: true, force: true });
+  });
+
+  it('caches a freshly entered (tty) secret', async () => {
+    await rememberVaultSecret('default', { password: 'typed-pw', source: 'tty' });
+    expect(await getVaultSecret('default')).toBe('typed-pw');
+  });
+
+  it('caches a first-run (explicit) secret', async () => {
+    await rememberVaultSecret('default', { password: 'wizard-pw', source: 'explicit' });
+    expect(await getVaultSecret('default')).toBe('wizard-pw');
+  });
+
+  it('does not cache an environment secret', async () => {
+    await rememberVaultSecret('default', { password: 'env-pw', source: 'env' });
+    expect(await getVaultSecret('default')).toBeUndefined();
+  });
+
+  it('does not re-cache an already-durable secret', async () => {
+    await rememberVaultSecret('default', { password: 'kc-pw', source: 'keychain' });
+    expect(await getVaultSecret('default')).toBeUndefined();
+  });
+
+  it('forgets a cached secret', async () => {
+    await rememberVaultSecret('default', { password: 'typed-pw', source: 'tty' });
+    await forgetVaultSecret('default');
+    expect(await getVaultSecret('default')).toBeUndefined();
+  });
+});