fix(cliproxy): respect version pin when user installs specific version

When a user explicitly installs a specific CLIProxy version via
`ccs cliproxy --install <version>`, this version should persist and
not be auto-updated. Previously, subsequent commands would check for
updates and overwrite the user's choice.

Changes:
- Add .version-pin file to persist user's explicit version choice
- Update ensureCLIProxyBinary() to check for version pin and skip auto-update
- Update --install command to save version pin with "(pinned)" confirmation
- Update --latest command to clear version pin and enable auto-update
- Add --update command as alias for --latest (for unpinning workflow)
- Update status display to show "(pinned)" indicator when version is pinned
- Update help text to document new pin/unpin behavior

Closes #88

src/cliproxy/binary-manager.ts

@@ -39,6 +39,9 @@ import {
 /** Cache duration for version check (1 hour in milliseconds) */
 const VERSION_CACHE_DURATION_MS = 60 * 60 * 1000;
 
+/** Version pin file name - stores user's explicit version choice */
+const VERSION_PIN_FILE = '.version-pin';
+
 /** GitHub API URL for latest release */
 const GITHUB_API_LATEST_RELEASE =
   'https://api.github.com/repos/router-for-me/CLIProxyAPI/releases/latest';
@@ -887,9 +890,26 @@ export class BinaryManager {
 
 /**
  * Convenience function to ensure binary is available
+ * Respects version pin if set by user via 'ccs cliproxy --install <version>'
  * @returns Path to CLIProxyAPI executable
  */
 export async function ensureCLIProxyBinary(verbose = false): Promise<string> {
+  const pinnedVersion = getPinnedVersion();
+
+  if (pinnedVersion) {
+    // Version is pinned - use forceVersion to prevent auto-update
+    if (verbose) {
+      console.error(`[cliproxy] Using pinned version: ${pinnedVersion}`);
+    }
+    const manager = new BinaryManager({
+      version: pinnedVersion,
+      verbose,
+      forceVersion: true,
+    });
+    return manager.ensureBinary();
+  }
+
+  // No pin - allow auto-update to latest
   const manager = new BinaryManager({ verbose });
   return manager.ensureBinary();
 }
@@ -960,4 +980,64 @@ export async function fetchLatestCliproxyVersion(): Promise<string> {
   return result.latestVersion;
 }
 
+/**
+ * Get path to version pin file
+ * @returns Absolute path to .version-pin file
+ */
+export function getVersionPinPath(): string {
+  return path.join(getBinDir(), VERSION_PIN_FILE);
+}
+
+/**
+ * Get pinned version if one exists
+ * @returns Pinned version string, or null if not pinned
+ */
+export function getPinnedVersion(): string | null {
+  const pinPath = getVersionPinPath();
+  if (!fs.existsSync(pinPath)) {
+    return null;
+  }
+  try {
+    return fs.readFileSync(pinPath, 'utf8').trim();
+  } catch {
+    return null;
+  }
+}
+
+/**
+ * Save pinned version to persist user's explicit choice
+ * @param version Version to pin (e.g., "6.5.50")
+ */
+export function savePinnedVersion(version: string): void {
+  const pinPath = getVersionPinPath();
+  try {
+    fs.mkdirSync(path.dirname(pinPath), { recursive: true });
+    fs.writeFileSync(pinPath, version, 'utf8');
+  } catch {
+    // Silent fail - not critical but log if verbose
+  }
+}
+
+/**
+ * Clear pinned version (unpin)
+ */
+export function clearPinnedVersion(): void {
+  const pinPath = getVersionPinPath();
+  if (fs.existsSync(pinPath)) {
+    try {
+      fs.unlinkSync(pinPath);
+    } catch {
+      // Silent fail
+    }
+  }
+}
+
+/**
+ * Check if a version is currently pinned
+ * @returns true if a version is pinned
+ */
+export function isVersionPinned(): boolean {
+  return getPinnedVersion() !== null;
+}
+
 export default BinaryManager;

src/cliproxy/index.ts

@@ -43,6 +43,11 @@ export {
   getInstalledCliproxyVersion,
   installCliproxyVersion,
   fetchLatestCliproxyVersion,
+  getPinnedVersion,
+  savePinnedVersion,
+  clearPinnedVersion,
+  isVersionPinned,
+  getVersionPinPath,
 } from './binary-manager';
 
 // Config generation

src/commands/cliproxy-command.ts

@@ -26,6 +26,10 @@ import {
   fetchLatestCliproxyVersion,
   isCLIProxyInstalled,
   getCLIProxyPath,
+  getPinnedVersion,
+  savePinnedVersion,
+  clearPinnedVersion,
+  isVersionPinned,
 } from '../cliproxy';
 import { getAllAuthStatus, getOAuthConfig, triggerOAuth } from '../cliproxy/auth-handler';
 import { getProviderAccounts } from '../cliproxy/account-manager';
@@ -803,8 +807,9 @@ async function showHelp(): Promise<void> {
   // Binary Commands
   console.log(subheader('Binary Commands:'));
   const binaryCmds: [string, string][] = [
-    ['--install <version>', 'Install a specific binary version'],
-    ['--latest', 'Install the latest binary version'],
+    ['--install <version>', 'Install and pin a specific version'],
+    ['--latest', 'Install the latest version (no pin)'],
+    ['--update', 'Unpin and update to latest version'],
   ];
   const maxBinaryLen = Math.max(...binaryCmds.map(([cmd]) => cmd.length));
   for (const [cmd, desc] of binaryCmds) {
@@ -897,6 +902,7 @@ async function showStatus(verbose: boolean): Promise<void> {
   const installed = isCLIProxyInstalled();
   const currentVersion = getInstalledCliproxyVersion();
   const binaryPath = getCLIProxyPath();
+  const pinnedVersion = getPinnedVersion();
 
   console.log('');
   console.log(color('CLIProxyAPI Status', 'primary'));
@@ -904,7 +910,10 @@ async function showStatus(verbose: boolean): Promise<void> {
 
   if (installed) {
     console.log(`  Installed:  ${color('Yes', 'success')}`);
-    console.log(`  Version:    ${color(`v${currentVersion}`, 'info')}`);
+    const versionLabel = pinnedVersion
+      ? `${color(`v${currentVersion}`, 'info')} ${color('(pinned)', 'warning')}`
+      : color(`v${currentVersion}`, 'info');
+    console.log(`  Version:    ${versionLabel}`);
     console.log(`  Binary:     ${dim(binaryPath)}`);
   } else {
     console.log(`  Installed:  ${color('No', 'error')}`);
@@ -919,11 +928,19 @@ async function showStatus(verbose: boolean): Promise<void> {
     const latestVersion = await fetchLatestCliproxyVersion();
 
     if (latestVersion !== currentVersion) {
-      console.log(
-        `  Latest:     ${color(`v${latestVersion}`, 'success')} ${dim('(update available)')}`
-      );
-      console.log('');
-      console.log(`  ${dim(`Run "ccs cliproxy --latest" to update`)}`);
+      if (pinnedVersion) {
+        console.log(
+          `  Latest:     ${color(`v${latestVersion}`, 'success')} ${dim('(pinned to v' + pinnedVersion + ')')}`
+        );
+        console.log('');
+        console.log(`  ${dim('Run "ccs cliproxy --update" to unpin and update')}`);
+      } else {
+        console.log(
+          `  Latest:     ${color(`v${latestVersion}`, 'success')} ${dim('(update available)')}`
+        );
+        console.log('');
+        console.log(`  ${dim('Run "ccs cliproxy --latest" to update')}`);
+      }
     } else {
       console.log(`  Latest:     ${color(`v${latestVersion}`, 'success')} ${dim('(up to date)')}`);
     }
@@ -940,7 +957,7 @@ async function showStatus(verbose: boolean): Promise<void> {
 }
 
 /**
- * Install a specific version
+ * Install a specific version (pins the version to prevent auto-update)
  */
 async function installVersion(version: string, verbose: boolean): Promise<void> {
   // Validate version format (basic semver check)
@@ -954,8 +971,18 @@ async function installVersion(version: string, verbose: boolean): Promise<void>
 
   try {
     await installCliproxyVersion(version, verbose);
+
+    // Pin the version to prevent auto-update
+    savePinnedVersion(version);
+
+    console.log('');
+    console.log(ok(`CLIProxyAPI v${version} installed (pinned)`));
+    console.log('');
+    console.log(dim('This version will be used until you run:'));
+    console.log(
+      `  ${color('ccs cliproxy --update', 'command')}  ${dim('# Update to latest and unpin')}`
+    );
     console.log('');
-    console.log(ok(`CLIProxyAPI v${version} installed successfully`));
   } catch (error) {
     const err = error as Error;
     console.error('');
@@ -974,7 +1001,7 @@ async function installVersion(version: string, verbose: boolean): Promise<void>
 }
 
 /**
- * Install latest version
+ * Install latest version (clears any version pin)
  */
 async function installLatest(verbose: boolean): Promise<void> {
   console.log(info('Fetching latest CLIProxyAPI version...'));
@@ -982,8 +1009,9 @@ async function installLatest(verbose: boolean): Promise<void> {
   try {
     const latestVersion = await fetchLatestCliproxyVersion();
     const currentVersion = getInstalledCliproxyVersion();
+    const wasPinned = isVersionPinned();
 
-    if (isCLIProxyInstalled() && latestVersion === currentVersion) {
+    if (isCLIProxyInstalled() && latestVersion === currentVersion && !wasPinned) {
       console.log(ok(`Already running latest version: v${latestVersion}`));
       return;
     }
@@ -992,11 +1020,20 @@ async function installLatest(verbose: boolean): Promise<void> {
     if (isCLIProxyInstalled()) {
       console.log(info(`Current version: v${currentVersion}`));
     }
+    if (wasPinned) {
+      console.log(info(`Removing version pin (was v${getPinnedVersion()})`));
+    }
     console.log('');
 
     await installCliproxyVersion(latestVersion, verbose);
+
+    // Clear any version pin so auto-update works again
+    clearPinnedVersion();
+
     console.log('');
     console.log(ok(`CLIProxyAPI updated to v${latestVersion}`));
+    console.log(dim('Auto-update is now enabled.'));
+    console.log('');
   } catch (error) {
     const err = error as Error;
     console.error(fail(`Failed to install latest version: ${err.message}`));
@@ -1057,6 +1094,12 @@ export async function handleCliproxyCommand(args: string[]): Promise<void> {
     return;
   }
 
+  // Handle --update (unpin and update to latest)
+  if (args.includes('--update')) {
+    await installLatest(verbose);
+    return;
+  }
+
   // Default: show status
   await showStatus(verbose);
 }