diff --git a/src/commands/update-command.ts b/src/commands/update-command.ts
index c78329c9..a85a38a3 100644
--- a/src/commands/update-command.ts
+++ b/src/commands/update-command.ts
@@ -7,7 +7,14 @@
 
 import { spawn } from 'child_process';
 import { initUI, header, ok, fail, warn, info, color } from '../utils/ui';
-import { detectPackageManager } from '../utils/package-manager-detector';
+import {
+  buildPackageManagerEnv,
+  detectCurrentInstall,
+  formatManualUpdateCommand,
+  readInstalledPackageState,
+  type CurrentInstall,
+  type InstalledPackageState,
+} from '../utils/package-manager-detector';
 import { compareVersionsWithPrerelease } from '../utils/update-checker';
 import { getVersion } from '../utils/version';
 
@@ -22,6 +29,24 @@ export interface UpdateOptions {
 // Version (from centralized utility)
 const CCS_VERSION = getVersion();
 
+async function resolveTargetVersion(
+  currentVersion: string,
+  targetTag: 'latest' | 'dev'
+): Promise<string | undefined> {
+  const { checkForUpdates } = await import('../utils/update-checker');
+  const result = await checkForUpdates(currentVersion, true, 'npm', targetTag);
+
+  if (result.status === 'update_available' && result.latest) {
+    return result.latest;
+  }
+
+  if (result.status === 'no_update') {
+    return currentVersion;
+  }
+
+  return undefined;
+}
+
 /**
  * Handle the update command
  * Checks for updates and installs the latest version
@@ -30,6 +55,7 @@ export async function handleUpdateCommand(options: UpdateOptions = {}): Promise<
   await initUI();
   const { force = false, beta = false } = options;
   const targetTag = beta ? 'dev' : 'latest';
+  const currentInstall = detectCurrentInstall();
 
   console.log('');
   console.log(header('Checking for updates...'));
@@ -39,16 +65,16 @@ export async function handleUpdateCommand(options: UpdateOptions = {}): Promise<
   if (force) {
     console.log(info(`Force reinstall from @${targetTag} channel...`));
     console.log('');
-    await performNpmUpdate(targetTag, true);
+    const expectedVersion = await resolveTargetVersion(CCS_VERSION, targetTag);
+    await performNpmUpdate(currentInstall, targetTag, true, expectedVersion);
     return;
   }
 
   const { checkForUpdates } = await import('../utils/update-checker');
-
   const updateResult = await checkForUpdates(CCS_VERSION, true, 'npm', targetTag);
 
   if (updateResult.status === 'check_failed') {
-    handleCheckFailed(updateResult.message ?? 'Update check failed', targetTag);
+    handleCheckFailed(updateResult.message ?? 'Update check failed', targetTag, currentInstall);
     return;
   }
 
@@ -89,13 +115,17 @@ export async function handleUpdateCommand(options: UpdateOptions = {}): Promise<
     console.log('');
   }
 
-  await performNpmUpdate(targetTag);
+  await performNpmUpdate(currentInstall, targetTag, false, updateResult.latest);
 }
 
 /**
  * Handle failed update check
  */
-function handleCheckFailed(message: string, targetTag: string = 'latest'): void {
+function handleCheckFailed(
+  message: string,
+  targetTag: string = 'latest',
+  currentInstall: CurrentInstall = detectCurrentInstall()
+): void {
   console.log(fail(message));
   console.log('');
   console.log(warn('Possible causes:'));
@@ -105,27 +135,7 @@ function handleCheckFailed(message: string, targetTag: string = 'latest'): void
   console.log('');
   console.log('Try again later or update manually:');
 
-  const packageManager = detectPackageManager();
-  let manualCommand: string;
-
-  switch (packageManager) {
-    case 'npm':
-      manualCommand = `npm install -g @kaitranntt/ccs@${targetTag}`;
-      break;
-    case 'yarn':
-      manualCommand = `yarn global add @kaitranntt/ccs@${targetTag}`;
-      break;
-    case 'pnpm':
-      manualCommand = `pnpm add -g @kaitranntt/ccs@${targetTag}`;
-      break;
-    case 'bun':
-      manualCommand = `bun add -g @kaitranntt/ccs@${targetTag}`;
-      break;
-    default:
-      manualCommand = `npm install -g @kaitranntt/ccs@${targetTag}`;
-  }
-
-  console.log(color(`  ${manualCommand}`, 'command'));
+  console.log(color(`  ${formatManualUpdateCommand(targetTag, currentInstall)}`, 'command'));
   console.log('');
   process.exit(1);
 }
@@ -157,15 +167,94 @@ function handleNoUpdate(reason: string | undefined): void {
 /**
  * Perform update via npm/yarn/pnpm/bun
  */
-async function performNpmUpdate(
-  targetTag: string = 'latest',
+function verifyCurrentInstallVersion(
+  currentInstall: CurrentInstall,
+  targetTag: string,
+  expectedVersion?: string,
+  previousState?: InstalledPackageState,
   isReinstall: boolean = false
+): void {
+  const nextState = readInstalledPackageState(currentInstall);
+  const installedVersion = nextState.version;
+  if (!installedVersion) {
+    console.log('');
+    console.log(
+      fail('Update finished, but CCS could not verify the current installation version.')
+    );
+    console.log('');
+    console.log('Current install remains ambiguous. Re-run manually:');
+    console.log(color(`  ${formatManualUpdateCommand(targetTag, currentInstall)}`, 'command'));
+    console.log('');
+    process.exit(1);
+  }
+
+  const installChanged =
+    previousState !== undefined &&
+    (previousState.version !== nextState.version ||
+      previousState.packageJsonMtimeMs !== nextState.packageJsonMtimeMs ||
+      previousState.scriptMtimeMs !== nextState.scriptMtimeMs);
+
+  if (expectedVersion && installedVersion !== expectedVersion) {
+    if (previousState?.version && installedVersion !== previousState.version) {
+      return;
+    }
+
+    const comparison = compareVersionsWithPrerelease(installedVersion, expectedVersion);
+    if (comparison < 0) {
+      console.log('');
+      console.log(
+        fail(
+          `Update completed outside the current installation. Current binary still reports ${installedVersion}; expected ${expectedVersion}.`
+        )
+      );
+      if (previousState?.version && previousState.version === installedVersion) {
+        console.log(
+          warn(
+            `The current install path did not change from ${previousState.version}; another package manager likely updated a different copy of CCS.`
+          )
+        );
+      }
+      console.log('');
+      console.log('Re-run manually against the current install:');
+      console.log(color(`  ${formatManualUpdateCommand(targetTag, currentInstall)}`, 'command'));
+      console.log('');
+      process.exit(1);
+    }
+  }
+
+  if (
+    isReinstall &&
+    previousState?.version &&
+    installedVersion === previousState.version &&
+    !installChanged
+  ) {
+    console.log('');
+    console.log(
+      fail(
+        `Reinstall completed, but CCS could not verify that the current installation changed from ${previousState.version}.`
+      )
+    );
+    console.log('');
+    console.log('Re-run manually against the current install:');
+    console.log(color(`  ${formatManualUpdateCommand(targetTag, currentInstall)}`, 'command'));
+    console.log('');
+    process.exit(1);
+  }
+}
+
+async function performNpmUpdate(
+  currentInstall: CurrentInstall,
+  targetTag: string = 'latest',
+  isReinstall: boolean = false,
+  expectedVersion?: string
 ): Promise<void> {
-  const packageManager = detectPackageManager();
+  const packageManager = currentInstall.manager;
   let updateCommand: string;
   let updateArgs: string[];
   let cacheCommand: string | null;
   let cacheArgs: string[] | null;
+  const childEnv = buildPackageManagerEnv(currentInstall);
+  const previousState = readInstalledPackageState(currentInstall);
 
   switch (packageManager) {
     case 'npm':
@@ -214,9 +303,9 @@ async function performNpmUpdate(
       ? spawn(`${updateCommand} ${updateArgs.join(' ')}`, [], {
           stdio: ['inherit', 'inherit', 'pipe'],
           shell: true,
-          env: { ...process.env, NODE_NO_WARNINGS: '1' },
+          env: { ...childEnv, NODE_NO_WARNINGS: '1' },
         })
-      : spawn(updateCommand, updateArgs, { stdio: 'inherit' });
+      : spawn(updateCommand, updateArgs, { stdio: 'inherit', env: childEnv });
 
     // On Windows, filter stderr to hide npm cleanup warnings (EPERM on bcrypt.node etc.)
     // These warnings are cosmetic - update succeeds despite file locking by antivirus/indexing
@@ -244,6 +333,15 @@ async function performNpmUpdate(
 
     child.on('exit', (code) => {
       if (code === 0) {
+        if (expectedVersion || previousState?.version) {
+          verifyCurrentInstallVersion(
+            currentInstall,
+            targetTag,
+            expectedVersion,
+            previousState,
+            isReinstall
+          );
+        }
         console.log('');
         console.log(ok(`${isReinstall ? 'Reinstall' : 'Update'} successful!`));
         console.log('');
@@ -255,7 +353,7 @@ async function performNpmUpdate(
         console.log(fail(`${isReinstall ? 'Reinstall' : 'Update'} failed`));
         console.log('');
         console.log('Try manually:');
-        console.log(color(`  ${updateCommand} ${updateArgs.join(' ')}`, 'command'));
+        console.log(color(`  ${formatManualUpdateCommand(targetTag, currentInstall)}`, 'command'));
         console.log('');
       }
       process.exit(code || 0);
@@ -266,7 +364,7 @@ async function performNpmUpdate(
       console.log(fail(`Failed to run ${packageManager} ${isReinstall ? 'reinstall' : 'update'}`));
       console.log('');
       console.log('Try manually:');
-      console.log(color(`  ${updateCommand} ${updateArgs.join(' ')}`, 'command'));
+      console.log(color(`  ${formatManualUpdateCommand(targetTag, currentInstall)}`, 'command'));
       console.log('');
       process.exit(1);
     });
@@ -288,9 +386,9 @@ async function performNpmUpdate(
       ? spawn(`${cacheCommand} ${cacheArgs.join(' ')}`, [], {
           stdio: 'inherit',
           shell: true,
-          env: { ...process.env, NODE_NO_WARNINGS: '1' },
+          env: { ...childEnv, NODE_NO_WARNINGS: '1' },
         })
-      : spawn(cacheCommand, cacheArgs, { stdio: 'inherit' });
+      : spawn(cacheCommand, cacheArgs, { stdio: 'inherit', env: childEnv });
 
     cacheChild.on('exit', (code) => {
       if (code !== 0) {
diff --git a/src/utils/package-manager-detector.ts b/src/utils/package-manager-detector.ts
index ac5840a0..4e5cea35 100644
--- a/src/utils/package-manager-detector.ts
+++ b/src/utils/package-manager-detector.ts
@@ -1,75 +1,338 @@
 /**
  * Package Manager Detector Utilities
  *
- * Cross-platform package manager detection utilities for CCS.
- * Now only supports npm-based installation (npm/yarn/pnpm/bun).
+ * Detect the package manager and install root that own the CURRENT CCS binary.
+ * This is intentionally different from "which package manager has CCS installed
+ * somewhere on the machine" because self-update must target the current install.
  */
 
-import * as path from 'path';
 import * as fs from 'fs';
-import { spawnSync } from 'child_process';
+import * as path from 'path';
+
+export type PackageManager = 'npm' | 'yarn' | 'pnpm' | 'bun';
+
+export interface CurrentInstall {
+  manager: PackageManager;
+  scriptPath: string;
+  resolvedScriptPath: string;
+  packageRoot: string | null;
+  prefix: string | null;
+  detectionSource: 'path' | 'package-root' | 'default';
+}
+
+export interface InstalledPackageState {
+  version: string | null;
+  packageJsonMtimeMs: number | null;
+  scriptMtimeMs: number | null;
+}
+
+const CCS_PACKAGE_NAME = '@kaitranntt/ccs';
+
+function resolveScriptPath(scriptPath: string): string {
+  if (path.win32.isAbsolute(scriptPath)) {
+    return scriptPath;
+  }
+
+  try {
+    return fs.realpathSync(scriptPath);
+  } catch {
+    return path.resolve(scriptPath);
+  }
+}
+
+function findPackageRoot(scriptPath: string): string | null {
+  let currentDir = path.dirname(scriptPath);
+
+  for (let i = 0; i < 8; i++) {
+    const packageJsonPath = path.join(currentDir, 'package.json');
+    if (fs.existsSync(packageJsonPath)) {
+      try {
+        const packageJson = JSON.parse(fs.readFileSync(packageJsonPath, 'utf8')) as {
+          name?: string;
+        };
+        if (packageJson.name === CCS_PACKAGE_NAME) {
+          return currentDir;
+        }
+      } catch {
+        // Ignore malformed package.json and keep walking upward.
+      }
+    }
+
+    const parentDir = path.dirname(currentDir);
+    if (parentDir === currentDir) {
+      break;
+    }
+    currentDir = parentDir;
+  }
+
+  return null;
+}
+
+function getPrefixBeforeMarker(packageRoot: string, marker: string): string | null {
+  const index = packageRoot.lastIndexOf(marker);
+  return index >= 0 ? packageRoot.slice(0, index) || path.parse(packageRoot).root : null;
+}
+
+function inferInstallFromPath(
+  targetPath: string
+): Pick<CurrentInstall, 'manager' | 'prefix'> | null {
+  const normalizedPath = targetPath.split(path.sep).join('/');
+
+  if (
+    normalizedPath.includes(`/install/global/node_modules/@kaitranntt/ccs`) ||
+    normalizedPath.includes(`/.bun/install/global/node_modules/@kaitranntt/ccs`)
+  ) {
+    return {
+      manager: 'bun',
+      prefix: getPrefixBeforeMarker(
+        targetPath,
+        `${path.sep}install${path.sep}global${path.sep}node_modules`
+      ),
+    };
+  }
+
+  if (normalizedPath.includes(`/global/node_modules/@kaitranntt/ccs`)) {
+    return {
+      manager: 'yarn',
+      prefix: getPrefixBeforeMarker(targetPath, `${path.sep}global${path.sep}node_modules`),
+    };
+  }
+
+  if (
+    normalizedPath.includes('/global/') &&
+    normalizedPath.includes('/.pnpm/') &&
+    normalizedPath.includes('/node_modules/@kaitranntt/ccs')
+  ) {
+    const pnpmVirtualStoreMatch = targetPath.match(
+      new RegExp(
+        `${path.sep.replace(/\\/g, '\\\\')}global${path.sep.replace(/\\/g, '\\\\')}[^${path.sep.replace(
+          /\\/g,
+          '\\\\'
+        )}]+${path.sep.replace(/\\/g, '\\\\')}\\.pnpm${path.sep.replace(/\\/g, '\\\\')}`
+      )
+    );
+    if (pnpmVirtualStoreMatch) {
+      return {
+        manager: 'pnpm',
+        prefix: getPrefixBeforeMarker(targetPath, `${path.sep}global${path.sep}`),
+      };
+    }
+  }
+
+  if (
+    normalizedPath.includes('/global/') &&
+    normalizedPath.includes('/node_modules/@kaitranntt/ccs')
+  ) {
+    return {
+      manager: 'pnpm',
+      prefix: getPrefixBeforeMarker(targetPath, `${path.sep}global${path.sep}`),
+    };
+  }
+
+  if (
+    normalizedPath.includes('/.pnpm/') &&
+    normalizedPath.includes('/node_modules/@kaitranntt/ccs')
+  ) {
+    return {
+      manager: 'pnpm',
+      prefix: null,
+    };
+  }
+
+  if (normalizedPath.includes('/lib/node_modules/@kaitranntt/ccs')) {
+    return {
+      manager: 'npm',
+      prefix: getPrefixBeforeMarker(targetPath, `${path.sep}lib${path.sep}node_modules`),
+    };
+  }
+
+  if (
+    normalizedPath.includes('/node_modules/@kaitranntt/ccs') &&
+    !normalizedPath.includes('/global/node_modules/@kaitranntt/ccs') &&
+    !normalizedPath.includes('/install/global/node_modules/@kaitranntt/ccs') &&
+    !normalizedPath.includes('/.pnpm/')
+  ) {
+    return {
+      manager: 'npm',
+      prefix: getPrefixBeforeMarker(targetPath, `${path.sep}node_modules`),
+    };
+  }
+
+  return null;
+}
 
 /**
- * Detect which package manager was used for installation
+ * Detect the current install owner from the path of the running script.
+ * Defaults to npm when the path is ambiguous because npm's global layout is
+ * the safest fallback for the existing manual remediation commands.
  */
-export function detectPackageManager(): 'npm' | 'yarn' | 'pnpm' | 'bun' {
-  const scriptPath = process.argv[1];
+export function detectCurrentInstall(scriptPath: string = process.argv[1] || ''): CurrentInstall {
+  const resolvedScriptPath = resolveScriptPath(scriptPath);
+  const pathMatch = inferInstallFromPath(resolvedScriptPath) ?? inferInstallFromPath(scriptPath);
+  const packageRoot = findPackageRoot(resolvedScriptPath);
 
-  // Check if script path contains package manager indicators
-  if (scriptPath.includes('.pnpm')) return 'pnpm';
-  if (scriptPath.includes('yarn')) return 'yarn';
-  if (scriptPath.includes('bun')) return 'bun';
-
-  // Check parent directories for lock files
-  const binDir = path.dirname(scriptPath);
-
-  let checkDir = binDir;
-  for (let i = 0; i < 5; i++) {
-    if (fs.existsSync(path.join(checkDir, 'pnpm-lock.yaml'))) return 'pnpm';
-    if (fs.existsSync(path.join(checkDir, 'yarn.lock'))) return 'yarn';
-    if (fs.existsSync(path.join(checkDir, 'bun.lockb'))) return 'bun';
-    checkDir = path.dirname(checkDir);
+  if (pathMatch) {
+    return {
+      manager: pathMatch.manager,
+      scriptPath,
+      resolvedScriptPath,
+      packageRoot,
+      prefix: pathMatch.prefix,
+      detectionSource: 'path',
+    };
   }
 
-  // Check if package managers are available on the system
-  try {
-    const yarnResult = spawnSync('yarn', ['global', 'list', '--pattern', '@kaitranntt/ccs'], {
-      encoding: 'utf8',
-      shell: true,
-      timeout: 5000,
-    });
-    if (yarnResult.status === 0 && yarnResult.stdout.includes('@kaitranntt/ccs')) {
-      return 'yarn';
+  if (packageRoot) {
+    const packageRootMatch = inferInstallFromPath(packageRoot);
+    if (packageRootMatch) {
+      return {
+        manager: packageRootMatch.manager,
+        scriptPath,
+        resolvedScriptPath,
+        packageRoot,
+        prefix: packageRootMatch.prefix,
+        detectionSource: 'package-root',
+      };
     }
-  } catch (_err) {
-    // Continue to next check
   }
 
+  return {
+    manager: 'npm',
+    scriptPath,
+    resolvedScriptPath,
+    packageRoot,
+    prefix: null,
+    detectionSource: 'default',
+  };
+}
+
+/**
+ * Backward-compatible helper for callers that only need the package manager.
+ */
+export function detectPackageManager(scriptPath: string = process.argv[1] || ''): PackageManager {
+  return detectCurrentInstall(scriptPath).manager;
+}
+
+export function buildPackageManagerEnv(
+  install: CurrentInstall,
+  baseEnv: NodeJS.ProcessEnv = process.env
+): NodeJS.ProcessEnv {
+  if (!install.prefix) {
+    return { ...baseEnv };
+  }
+
+  switch (install.manager) {
+    case 'npm':
+      return {
+        ...baseEnv,
+        npm_config_prefix: install.prefix,
+        NPM_CONFIG_PREFIX: install.prefix,
+      };
+    case 'yarn':
+      return {
+        ...baseEnv,
+        YARN_GLOBAL_FOLDER: install.prefix,
+      };
+    case 'pnpm':
+      return {
+        ...baseEnv,
+        PNPM_HOME: install.prefix,
+      };
+    case 'bun':
+      return {
+        ...baseEnv,
+        BUN_INSTALL: install.prefix,
+      };
+    default:
+      return { ...baseEnv };
+  }
+}
+
+export function readInstalledPackageVersion(install: CurrentInstall): string | null {
+  return readInstalledPackageState(install).version;
+}
+
+function readFileMtimeMs(filePath: string): number | null {
   try {
-    const pnpmResult = spawnSync('pnpm', ['list', '-g', '--pattern', '@kaitranntt/ccs'], {
-      encoding: 'utf8',
-      shell: true,
-      timeout: 5000,
-    });
-    if (pnpmResult.status === 0 && pnpmResult.stdout.includes('@kaitranntt/ccs')) {
-      return 'pnpm';
-    }
-  } catch (_err) {
-    // Continue to next check
+    return fs.statSync(filePath).mtimeMs;
+  } catch {
+    return null;
+  }
+}
+
+export function readInstalledPackageState(install: CurrentInstall): InstalledPackageState {
+  if (!install.packageRoot) {
+    return {
+      version: null,
+      packageJsonMtimeMs: null,
+      scriptMtimeMs: readFileMtimeMs(install.resolvedScriptPath),
+    };
   }
 
+  const packageJsonPath = path.join(install.packageRoot, 'package.json');
+  const packageJsonMtimeMs = readFileMtimeMs(packageJsonPath);
+  const scriptMtimeMs = readFileMtimeMs(install.resolvedScriptPath);
+
   try {
-    const bunResult = spawnSync('bun', ['pm', 'ls', '-g', '--pattern', '@kaitranntt/ccs'], {
-      encoding: 'utf8',
-      shell: true,
-      timeout: 5000,
-    });
-    if (bunResult.status === 0 && bunResult.stdout.includes('@kaitranntt/ccs')) {
-      return 'bun';
-    }
-  } catch (_err) {
-    // Continue to default
-  }
-
-  return 'npm';
+    const packageJson = JSON.parse(fs.readFileSync(packageJsonPath, 'utf8')) as {
+      version?: string;
+    };
+
+    return {
+      version: typeof packageJson.version === 'string' ? packageJson.version : null,
+      packageJsonMtimeMs,
+      scriptMtimeMs,
+    };
+  } catch {
+    return {
+      version: null,
+      packageJsonMtimeMs,
+      scriptMtimeMs,
+    };
+  }
+}
+
+function quoteForShell(value: string): string {
+  if (/^[A-Za-z0-9_./:-]+$/.test(value)) {
+    return value;
+  }
+  return `'${value.replace(/'/g, `'\\''`)}'`;
+}
+
+function quoteForCmd(value: string): string {
+  return value.replace(/'/g, "''");
+}
+
+function formatWindowsEnvCommand(envVar: string, value: string, command: string): string {
+  return `powershell -NoProfile -Command "$env:${envVar}='${quoteForCmd(value)}'; ${command}"`;
+}
+
+export function formatManualUpdateCommand(
+  targetTag: string,
+  install: CurrentInstall = detectCurrentInstall(),
+  platform: NodeJS.Platform = process.platform
+): string {
+  const command = {
+    npm: `npm install -g @kaitranntt/ccs@${targetTag}`,
+    yarn: `yarn global add @kaitranntt/ccs@${targetTag}`,
+    pnpm: `pnpm add -g @kaitranntt/ccs@${targetTag}`,
+    bun: `bun add -g @kaitranntt/ccs@${targetTag}`,
+  }[install.manager];
+
+  if (!install.prefix) {
+    return command;
+  }
+
+  const envVar = {
+    npm: 'NPM_CONFIG_PREFIX',
+    yarn: 'YARN_GLOBAL_FOLDER',
+    pnpm: 'PNPM_HOME',
+    bun: 'BUN_INSTALL',
+  }[install.manager];
+
+  if (platform === 'win32') {
+    return formatWindowsEnvCommand(envVar, install.prefix, command);
+  }
+
+  return `${envVar}=${quoteForShell(install.prefix)} ${command}`;
 }
diff --git a/tests/integration/update-command-install-origin.test.ts b/tests/integration/update-command-install-origin.test.ts
new file mode 100644
index 00000000..ab10fabe
--- /dev/null
+++ b/tests/integration/update-command-install-origin.test.ts
@@ -0,0 +1,185 @@
+import { afterEach, beforeEach, describe, expect, it, mock } from 'bun:test';
+import { chmodSync, mkdtempSync, mkdirSync, readFileSync, rmSync, writeFileSync } from 'fs';
+import { tmpdir } from 'os';
+import { join } from 'path';
+
+let tempRoot = '';
+let currentPackageRoot = '';
+let currentPrefix = '';
+let bunPackageRoot = '';
+let fakeBinDir = '';
+let originalArgv1 = '';
+let originalPath = '';
+let originalConsoleLog: typeof console.log;
+let originalProcessExit: typeof process.exit;
+let logLines: string[] = [];
+let exitCodes: number[] = [];
+
+function writePackage(root: string, version: string): void {
+  mkdirSync(root, { recursive: true });
+  writeFileSync(
+    join(root, 'package.json'),
+    JSON.stringify({ name: '@kaitranntt/ccs', version }, null, 2)
+  );
+}
+
+function readPackageVersion(root: string): string {
+  return JSON.parse(readFileSync(join(root, 'package.json'), 'utf8')).version as string;
+}
+
+function writeExecutable(filePath: string, contents: string): void {
+  writeFileSync(filePath, contents);
+  chmodSync(filePath, 0o755);
+}
+
+async function loadHandleUpdateCommand() {
+  const mod = await import(`../../src/commands/update-command?test=${Date.now()}-${Math.random()}`);
+  return mod.handleUpdateCommand;
+}
+
+beforeEach(() => {
+  tempRoot = mkdtempSync(join(tmpdir(), 'ccs-update-origin-'));
+  currentPrefix = join(tempRoot, 'prefix');
+  currentPackageRoot = join(currentPrefix, 'lib', 'node_modules', '@kaitranntt', 'ccs');
+  bunPackageRoot = join(
+    tempRoot,
+    '.bun',
+    'install',
+    'global',
+    'node_modules',
+    '@kaitranntt',
+    'ccs'
+  );
+  fakeBinDir = join(tempRoot, 'bin');
+
+  mkdirSync(join(currentPackageRoot, 'dist'), { recursive: true });
+  mkdirSync(fakeBinDir, { recursive: true });
+  writePackage(currentPackageRoot, '7.67.0-dev.5');
+  writePackage(bunPackageRoot, '0.0.0-stale');
+
+  originalArgv1 = process.argv[1] ?? '';
+  process.argv[1] = join(currentPackageRoot, 'dist', 'ccs.js');
+
+  originalPath = process.env.PATH ?? '';
+  process.env.PATH = `${fakeBinDir}:${originalPath}`;
+
+  logLines = [];
+  exitCodes = [];
+  originalConsoleLog = console.log;
+  console.log = (...args: unknown[]) => {
+    logLines.push(args.map(String).join(' '));
+  };
+
+  originalProcessExit = process.exit;
+  process.exit = ((code?: number) => {
+    exitCodes.push(code ?? 0);
+  }) as typeof process.exit;
+
+  mock.module('../../src/utils/ui', () => ({
+    initUI: async () => {},
+    header: (value: string) => value,
+    ok: (value: string) => `[OK] ${value}`,
+    fail: (value: string) => `[X] ${value}`,
+    warn: (value: string) => `[!] ${value}`,
+    info: (value: string) => `[i] ${value}`,
+    color: (value: string) => value,
+  }));
+
+  mock.module('../../src/utils/version', () => ({
+    getVersion: () => '7.67.0-dev.5',
+  }));
+
+  mock.module('../../src/utils/update-checker', () => ({
+    compareVersionsWithPrerelease: (left: string, right: string) => left.localeCompare(right),
+    checkForUpdates: async () => ({
+      status: 'update_available',
+      current: '7.67.0-dev.5',
+      latest: '7.67.0-dev.9',
+    }),
+  }));
+});
+
+afterEach(() => {
+  console.log = originalConsoleLog;
+  process.exit = originalProcessExit;
+  process.argv[1] = originalArgv1;
+  process.env.PATH = originalPath;
+  mock.restore();
+  if (tempRoot) {
+    rmSync(tempRoot, { recursive: true, force: true });
+  }
+});
+
+async function waitForExitCode(expectedCode: number): Promise<void> {
+  for (let attempt = 0; attempt < 50; attempt++) {
+    if (exitCodes.includes(expectedCode)) {
+      return;
+    }
+    await new Promise((resolve) => setTimeout(resolve, 10));
+  }
+  throw new Error(`process.exit(${expectedCode}) was not observed`);
+}
+
+describe('update-command install origin integration', () => {
+  it('updates the current npm-owned install instead of drifting to another manager', async () => {
+    writeExecutable(
+      join(fakeBinDir, 'npm'),
+      `#!/bin/sh
+if [ "$npm_config_prefix" = "${currentPrefix}" ] || [ "$NPM_CONFIG_PREFIX" = "${currentPrefix}" ]; then
+  cat > "${join(currentPackageRoot, 'package.json')}" <<'EOF'
+{"name":"@kaitranntt/ccs","version":"7.67.0-dev.9"}
+EOF
+  exit 0
+fi
+exit 13
+`
+    );
+
+    writeExecutable(
+      join(fakeBinDir, 'bun'),
+      `#!/bin/sh
+cat > "${join(bunPackageRoot, 'package.json')}" <<'EOF'
+{"name":"@kaitranntt/ccs","version":"7.67.0-dev.9"}
+EOF
+exit 0
+`
+    );
+
+    const handleUpdateCommand = await loadHandleUpdateCommand();
+
+    await handleUpdateCommand({ beta: true });
+    await waitForExitCode(0);
+
+    expect(readPackageVersion(currentPackageRoot)).toBe('7.67.0-dev.9');
+    expect(readPackageVersion(bunPackageRoot)).toBe('0.0.0-stale');
+    expect(logLines.join('\n')).toContain('Updating via npm');
+  });
+
+  it('fails if the update exits 0 but the current install stays stale', async () => {
+    writeExecutable(
+      join(fakeBinDir, 'npm'),
+      `#!/bin/sh
+exit 0
+`
+    );
+
+    writeExecutable(
+      join(fakeBinDir, 'bun'),
+      `#!/bin/sh
+cat > "${join(bunPackageRoot, 'package.json')}" <<'EOF'
+{"name":"@kaitranntt/ccs","version":"7.67.0-dev.9"}
+EOF
+exit 0
+`
+    );
+
+    const handleUpdateCommand = await loadHandleUpdateCommand();
+
+    await handleUpdateCommand({ beta: true });
+    await waitForExitCode(1);
+
+    expect(readPackageVersion(currentPackageRoot)).toBe('7.67.0-dev.5');
+    expect(logLines.join('\n')).toContain('outside the current installation');
+    expect(logLines.join('\n')).toContain('NPM_CONFIG_PREFIX=');
+  });
+});
diff --git a/tests/unit/commands/update-command-current-install.test.ts b/tests/unit/commands/update-command-current-install.test.ts
new file mode 100644
index 00000000..33e7cf51
--- /dev/null
+++ b/tests/unit/commands/update-command-current-install.test.ts
@@ -0,0 +1,283 @@
+import { afterEach, beforeEach, describe, expect, it, mock } from 'bun:test';
+
+let logLines: string[] = [];
+let spawnCalls: Array<{ command: string; args: string[]; env?: NodeJS.ProcessEnv }> = [];
+let exitCodes: number[] = [];
+let stateReads = 0;
+let originalConsoleLog: typeof console.log;
+let originalProcessExit: typeof process.exit;
+let updateCheckResult:
+  | { status: 'update_available'; current: string; latest: string }
+  | { status: 'no_update' }
+  | { status: 'check_failed'; message: string };
+let currentInstallOverride = installDescriptor();
+
+type Scenario = {
+  beforeState: {
+    version: string | null;
+    packageJsonMtimeMs: number | null;
+    scriptMtimeMs: number | null;
+  };
+  afterState: {
+    version: string | null;
+    packageJsonMtimeMs: number | null;
+    scriptMtimeMs: number | null;
+  };
+};
+
+let scenario: Scenario;
+
+function installDescriptor() {
+  return {
+    manager: 'npm' as const,
+    scriptPath: '/tmp/ccs-prefix/bin/ccs',
+    resolvedScriptPath: '/tmp/ccs-prefix/lib/node_modules/@kaitranntt/ccs/dist/ccs.js',
+    packageRoot: '/tmp/ccs-prefix/lib/node_modules/@kaitranntt/ccs',
+    prefix: '/tmp/ccs-prefix',
+    detectionSource: 'path' as const,
+  };
+}
+
+beforeEach(() => {
+  logLines = [];
+  spawnCalls = [];
+  exitCodes = [];
+  stateReads = 0;
+  scenario = {
+    beforeState: { version: '7.67.0-dev.5', packageJsonMtimeMs: 100, scriptMtimeMs: 100 },
+    afterState: { version: '7.67.0-dev.9', packageJsonMtimeMs: 200, scriptMtimeMs: 200 },
+  };
+  updateCheckResult = {
+    status: 'update_available',
+    current: '7.67.0-dev.5',
+    latest: '7.67.0-dev.9',
+  };
+  currentInstallOverride = installDescriptor();
+
+  originalConsoleLog = console.log;
+  originalProcessExit = process.exit;
+
+  console.log = (...args: unknown[]) => {
+    logLines.push(args.map(String).join(' '));
+  };
+
+  process.exit = ((code?: number) => {
+    exitCodes.push(code ?? 0);
+    throw new Error(`process.exit(${code ?? 0})`);
+  }) as typeof process.exit;
+
+  mock.module('child_process', () => ({
+    spawn: (command: string, args: string[], options?: { env?: NodeJS.ProcessEnv }) => {
+      spawnCalls.push({ command, args, env: options?.env });
+      return {
+        on: (event: string, callback: (code?: number) => void) => {
+          if (event === 'exit') {
+            callback(0);
+          }
+        },
+      };
+    },
+  }));
+
+  mock.module('../../../src/utils/ui', () => ({
+    initUI: async () => {},
+    header: (value: string) => value,
+    ok: (value: string) => `[OK] ${value}`,
+    fail: (value: string) => `[X] ${value}`,
+    warn: (value: string) => `[!] ${value}`,
+    info: (value: string) => `[i] ${value}`,
+    color: (value: string) => value,
+  }));
+
+  mock.module('../../../src/utils/version', () => ({
+    getVersion: () => '7.67.0-dev.5',
+  }));
+
+  mock.module('../../../src/utils/update-checker', () => ({
+    compareVersionsWithPrerelease: (left: string, right: string) => left.localeCompare(right),
+    checkForUpdates: async () => updateCheckResult,
+  }));
+
+  mock.module('../../../src/utils/package-manager-detector', () => ({
+    detectCurrentInstall: () => currentInstallOverride,
+    buildPackageManagerEnv: () => {
+      if (currentInstallOverride.manager === 'npm') {
+        return {
+          PATH: '/usr/bin',
+          npm_config_prefix: '/tmp/ccs-prefix',
+          NPM_CONFIG_PREFIX: '/tmp/ccs-prefix',
+        };
+      }
+
+      if (currentInstallOverride.manager === 'bun') {
+        return { PATH: '/usr/bin', BUN_INSTALL: '/tmp/bun-prefix' };
+      }
+
+      if (currentInstallOverride.manager === 'yarn') {
+        return { PATH: '/usr/bin', YARN_GLOBAL_FOLDER: '/tmp/yarn-prefix' };
+      }
+
+      return { PATH: '/usr/bin', PNPM_HOME: '/tmp/pnpm-prefix' };
+    },
+    formatManualUpdateCommand: () => {
+      if (currentInstallOverride.manager === 'npm') {
+        return 'NPM_CONFIG_PREFIX=/tmp/ccs-prefix npm install -g @kaitranntt/ccs@dev';
+      }
+
+      if (currentInstallOverride.manager === 'bun') {
+        return 'BUN_INSTALL=/tmp/bun-prefix bun add -g @kaitranntt/ccs@dev';
+      }
+
+      if (currentInstallOverride.manager === 'yarn') {
+        return 'YARN_GLOBAL_FOLDER=/tmp/yarn-prefix yarn global add @kaitranntt/ccs@dev';
+      }
+
+      return 'PNPM_HOME=/tmp/pnpm-prefix pnpm add -g @kaitranntt/ccs@dev';
+    },
+    readInstalledPackageState: () => {
+      stateReads += 1;
+      return stateReads === 1 ? scenario.beforeState : scenario.afterState;
+    },
+  }));
+});
+
+afterEach(() => {
+  console.log = originalConsoleLog;
+  process.exit = originalProcessExit;
+  mock.restore();
+});
+
+async function loadHandleUpdateCommand() {
+  const mod = await import(
+    `../../../src/commands/update-command?test=${Date.now()}-${Math.random()}`
+  );
+  return mod.handleUpdateCommand;
+}
+
+describe('update-command current install handling', () => {
+  it('updates through the current install manager and prefix', async () => {
+    const handleUpdateCommand = await loadHandleUpdateCommand();
+
+    await expect(handleUpdateCommand({ beta: true })).rejects.toThrow('process.exit(0)');
+
+    const installCall = spawnCalls.find((call) => call.args.includes('install'));
+
+    expect(installCall?.command).toBe('npm');
+    expect(installCall?.args).toEqual(['install', '-g', '@kaitranntt/ccs@dev']);
+    expect(installCall?.env?.npm_config_prefix).toBe('/tmp/ccs-prefix');
+  });
+
+  it('fails when another manager updated elsewhere but the current binary stayed stale', async () => {
+    scenario = {
+      beforeState: { version: '7.67.0-dev.5', packageJsonMtimeMs: 100, scriptMtimeMs: 100 },
+      afterState: { version: '7.67.0-dev.5', packageJsonMtimeMs: 100, scriptMtimeMs: 100 },
+    };
+    const handleUpdateCommand = await loadHandleUpdateCommand();
+
+    await expect(handleUpdateCommand({ beta: true })).rejects.toThrow('process.exit(1)');
+
+    expect(logLines.join('\n')).toContain('outside the current installation');
+    expect(logLines.join('\n')).toContain(
+      'NPM_CONFIG_PREFIX=/tmp/ccs-prefix npm install -g @kaitranntt/ccs@dev'
+    );
+  });
+
+  it('keeps force mode under exact target-version verification', async () => {
+    scenario = {
+      beforeState: { version: '7.67.0-dev.5', packageJsonMtimeMs: 100, scriptMtimeMs: 100 },
+      afterState: { version: '7.67.0-dev.5', packageJsonMtimeMs: 100, scriptMtimeMs: 100 },
+    };
+    const handleUpdateCommand = await loadHandleUpdateCommand();
+
+    await expect(handleUpdateCommand({ force: true, beta: true })).rejects.toThrow(
+      'process.exit(1)'
+    );
+
+    expect(logLines.join('\n')).toContain('outside the current installation');
+  });
+
+  it('fails force mode when target resolution says no update and the current install stays unchanged', async () => {
+    scenario = {
+      beforeState: { version: '7.67.0-dev.5', packageJsonMtimeMs: 100, scriptMtimeMs: 100 },
+      afterState: { version: '7.67.0-dev.5', packageJsonMtimeMs: 100, scriptMtimeMs: 100 },
+    };
+    updateCheckResult = { status: 'no_update' };
+    const handleUpdateCommand = await loadHandleUpdateCommand();
+
+    await expect(handleUpdateCommand({ force: true, beta: true })).rejects.toThrow(
+      'process.exit(1)'
+    );
+
+    expect(logLines.join('\n')).toContain('could not verify that the current installation changed');
+  });
+
+  it('fails force mode when target version resolution fails and the current install stays unchanged', async () => {
+    scenario = {
+      beforeState: { version: '7.67.0-dev.5', packageJsonMtimeMs: 100, scriptMtimeMs: 100 },
+      afterState: { version: '7.67.0-dev.5', packageJsonMtimeMs: 100, scriptMtimeMs: 100 },
+    };
+    updateCheckResult = { status: 'check_failed', message: 'network' };
+    const handleUpdateCommand = await loadHandleUpdateCommand();
+
+    await expect(handleUpdateCommand({ force: true, beta: true })).rejects.toThrow(
+      'process.exit(1)'
+    );
+
+    expect(logLines.join('\n')).toContain('could not verify that the current installation changed');
+  });
+
+  it('accepts a newer installed version when the dist-tag moves during update', async () => {
+    scenario = {
+      beforeState: { version: '7.67.0-dev.5', packageJsonMtimeMs: 100, scriptMtimeMs: 100 },
+      afterState: { version: '7.67.1-dev.0', packageJsonMtimeMs: 200, scriptMtimeMs: 200 },
+    };
+    const handleUpdateCommand = await loadHandleUpdateCommand();
+
+    await expect(handleUpdateCommand({ beta: true })).rejects.toThrow('process.exit(0)');
+
+    expect(logLines.join('\n')).not.toContain('outside the current installation');
+  });
+
+  it('accepts force reinstall when the version stays the same but the current install files change', async () => {
+    scenario = {
+      beforeState: { version: '7.67.0-dev.5', packageJsonMtimeMs: 100, scriptMtimeMs: 100 },
+      afterState: { version: '7.67.0-dev.5', packageJsonMtimeMs: 200, scriptMtimeMs: 200 },
+    };
+    updateCheckResult = { status: 'no_update' };
+    const handleUpdateCommand = await loadHandleUpdateCommand();
+
+    await expect(handleUpdateCommand({ force: true, beta: true })).rejects.toThrow(
+      'process.exit(0)'
+    );
+
+    expect(logLines.join('\n')).not.toContain(
+      'could not verify that the current installation changed'
+    );
+  });
+
+  it.each([
+    ['bun', 'add', 'BUN_INSTALL', '/tmp/bun-prefix'],
+    ['yarn', 'global', 'YARN_GLOBAL_FOLDER', '/tmp/yarn-prefix'],
+    ['pnpm', 'add', 'PNPM_HOME', '/tmp/pnpm-prefix'],
+  ])(
+    'routes updates through the current %s install and env',
+    async (manager, expectedArg, envKey, envValue) => {
+      currentInstallOverride = {
+        ...installDescriptor(),
+        manager: manager as 'bun' | 'yarn' | 'pnpm',
+        prefix: envValue,
+      };
+
+      const handleUpdateCommand = await loadHandleUpdateCommand();
+
+      await expect(handleUpdateCommand({ beta: true })).rejects.toThrow('process.exit(0)');
+
+      const updateCall = spawnCalls.find(
+        (call) =>
+          call.command === manager && call.args.some((arg) => arg.includes('@kaitranntt/ccs@dev'))
+      );
+      expect(updateCall?.args).toContain(expectedArg);
+      expect(updateCall?.env?.[envKey]).toBe(envValue);
+    }
+  );
+});
diff --git a/tests/unit/utils/package-manager-detector.test.ts b/tests/unit/utils/package-manager-detector.test.ts
new file mode 100644
index 00000000..693e0920
--- /dev/null
+++ b/tests/unit/utils/package-manager-detector.test.ts
@@ -0,0 +1,211 @@
+import { afterEach, describe, expect, it } from 'bun:test';
+import { mkdtempSync, mkdirSync, rmSync, writeFileSync } from 'fs';
+import { tmpdir } from 'os';
+import { join } from 'path';
+import {
+  buildPackageManagerEnv,
+  detectCurrentInstall,
+  formatManualUpdateCommand,
+  readInstalledPackageVersion,
+} from '../../../src/utils/package-manager-detector';
+
+const tempDirs: string[] = [];
+
+function makeTempDir(prefix: string): string {
+  const dir = mkdtempSync(join(tmpdir(), prefix));
+  tempDirs.push(dir);
+  return dir;
+}
+
+function writePackage(root: string, version: string): void {
+  mkdirSync(root, { recursive: true });
+  writeFileSync(
+    join(root, 'package.json'),
+    JSON.stringify({ name: '@kaitranntt/ccs', version }, null, 2)
+  );
+}
+
+afterEach(() => {
+  while (tempDirs.length > 0) {
+    const dir = tempDirs.pop();
+    if (dir) {
+      rmSync(dir, { recursive: true, force: true });
+    }
+  }
+});
+
+describe('package-manager-detector', () => {
+  it('detects npm installs from the current binary path and keeps the custom prefix', () => {
+    const tempRoot = makeTempDir('ccs-install-detector-npm-');
+    const packageRoot = join(tempRoot, 'prefix', 'lib', 'node_modules', '@kaitranntt', 'ccs');
+    const scriptPath = join(packageRoot, 'dist', 'ccs.js');
+
+    writePackage(packageRoot, '7.67.0-dev.5');
+
+    const install = detectCurrentInstall(scriptPath);
+
+    expect(install.manager).toBe('npm');
+    expect(install.prefix).toBe(join(tempRoot, 'prefix'));
+    expect(install.packageRoot).toBe(packageRoot);
+    expect(readInstalledPackageVersion(install)).toBe('7.67.0-dev.5');
+  });
+
+  it('detects bun installs from the resolved package path', () => {
+    const tempRoot = makeTempDir('ccs-install-detector-bun-');
+    const packageRoot = join(
+      tempRoot,
+      '.bun',
+      'install',
+      'global',
+      'node_modules',
+      '@kaitranntt',
+      'ccs'
+    );
+    const scriptPath = join(packageRoot, 'dist', 'ccs.js');
+
+    writePackage(packageRoot, '7.67.0-dev.9');
+
+    const install = detectCurrentInstall(scriptPath);
+
+    expect(install.manager).toBe('bun');
+    expect(install.prefix).toBe(join(tempRoot, '.bun'));
+    expect(readInstalledPackageVersion(install)).toBe('7.67.0-dev.9');
+  });
+
+  it('detects custom bun install roots that still use install/global/node_modules', () => {
+    const tempRoot = makeTempDir('ccs-install-detector-custom-bun-');
+    const packageRoot = join(
+      tempRoot,
+      'custom-bun-root',
+      'install',
+      'global',
+      'node_modules',
+      '@kaitranntt',
+      'ccs'
+    );
+
+    writePackage(packageRoot, '7.67.0-dev.9');
+
+    const install = detectCurrentInstall(join(packageRoot, 'dist', 'ccs.js'));
+
+    expect(install.manager).toBe('bun');
+    expect(install.prefix).toBe(join(tempRoot, 'custom-bun-root'));
+  });
+
+  it('detects custom yarn global layouts', () => {
+    const tempRoot = makeTempDir('ccs-install-detector-custom-yarn-');
+    const packageRoot = join(
+      tempRoot,
+      'custom-yarn-root',
+      'global',
+      'node_modules',
+      '@kaitranntt',
+      'ccs'
+    );
+
+    writePackage(packageRoot, '7.67.0-dev.9');
+
+    const install = detectCurrentInstall(join(packageRoot, 'dist', 'ccs.js'));
+
+    expect(install.manager).toBe('yarn');
+    expect(install.prefix).toBe(join(tempRoot, 'custom-yarn-root'));
+  });
+
+  it('detects custom pnpm global layouts that include a store version segment', () => {
+    const tempRoot = makeTempDir('ccs-install-detector-custom-pnpm-');
+    const packageRoot = join(
+      tempRoot,
+      'custom-pnpm-root',
+      'global',
+      '5',
+      '.pnpm',
+      '@kaitranntt+ccs@7.67.0-dev.9',
+      'node_modules',
+      '@kaitranntt',
+      'ccs'
+    );
+
+    writePackage(packageRoot, '7.67.0-dev.9');
+
+    const install = detectCurrentInstall(join(packageRoot, 'dist', 'ccs.js'));
+
+    expect(install.manager).toBe('pnpm');
+    expect(install.prefix).toBe(join(tempRoot, 'custom-pnpm-root'));
+  });
+
+  it('detects pnpm global layouts without a visible .pnpm segment in the script path', () => {
+    const tempRoot = makeTempDir('ccs-install-detector-pnpm-global-flat-');
+    const packageRoot = join(
+      tempRoot,
+      'custom-pnpm-root',
+      'global',
+      '5',
+      'node_modules',
+      '@kaitranntt',
+      'ccs'
+    );
+
+    writePackage(packageRoot, '7.67.0-dev.9');
+
+    const install = detectCurrentInstall(join(packageRoot, 'dist', 'ccs.js'));
+
+    expect(install.manager).toBe('pnpm');
+    expect(install.prefix).toBe(join(tempRoot, 'custom-pnpm-root'));
+  });
+
+  it('detects Windows npm globals without a lib directory', () => {
+    const install = detectCurrentInstall(
+      'C:/Program Files/node-prefix/node_modules/@kaitranntt/ccs/dist/ccs.js'
+    );
+
+    expect(install.manager).toBe('npm');
+    expect(install.prefix).toBe('C:/Program Files/node-prefix');
+  });
+
+  it('formats manual npm update commands with the current prefix', () => {
+    const install = {
+      manager: 'npm' as const,
+      scriptPath: '/tmp/prefix/bin/ccs',
+      resolvedScriptPath: '/tmp/prefix/lib/node_modules/@kaitranntt/ccs/dist/ccs.js',
+      packageRoot: '/tmp/prefix/lib/node_modules/@kaitranntt/ccs',
+      prefix: '/tmp/prefix',
+      detectionSource: 'path' as const,
+    };
+
+    expect(formatManualUpdateCommand('dev', install)).toBe(
+      'NPM_CONFIG_PREFIX=/tmp/prefix npm install -g @kaitranntt/ccs@dev'
+    );
+  });
+
+  it('formats Windows-safe manual npm update commands for prefixes with spaces', () => {
+    const install = {
+      manager: 'npm' as const,
+      scriptPath: 'C:/Tools/CCS/ccs.cmd',
+      resolvedScriptPath: 'C:/Program Files/CCS/lib/node_modules/@kaitranntt/ccs/dist/ccs.js',
+      packageRoot: 'C:/Program Files/CCS/lib/node_modules/@kaitranntt/ccs',
+      prefix: 'C:/Program Files/CCS',
+      detectionSource: 'path' as const,
+    };
+
+    expect(formatManualUpdateCommand('dev', install, 'win32')).toBe(
+      `powershell -NoProfile -Command "$env:NPM_CONFIG_PREFIX='C:/Program Files/CCS'; npm install -g @kaitranntt/ccs@dev"`
+    );
+  });
+
+  it('builds manager-specific env overrides for the current install', () => {
+    const install = {
+      manager: 'npm' as const,
+      scriptPath: '/tmp/prefix/bin/ccs',
+      resolvedScriptPath: '/tmp/prefix/lib/node_modules/@kaitranntt/ccs/dist/ccs.js',
+      packageRoot: '/tmp/prefix/lib/node_modules/@kaitranntt/ccs',
+      prefix: '/tmp/prefix',
+      detectionSource: 'path' as const,
+    };
+
+    const env = buildPackageManagerEnv(install, { PATH: '/usr/bin' });
+
+    expect(env.PATH).toBe('/usr/bin');
+    expect(env.npm_config_prefix).toBe('/tmp/prefix');
+    expect(env.NPM_CONFIG_PREFIX).toBe('/tmp/prefix');
+  });
+});