diff --git a/package.json b/package.json
index 6b5f16c..f1fafa3 100644
--- a/package.json
+++ b/package.json
@@ -38,7 +38,7 @@
     "vitest": "^3.2.4"
   },
   "scripts": {
-    "build": "rm -rf dist && tsc -p tsconfig.build.json && cp -r src/command dist/command",
+    "build": "node scripts/build.mjs",
     "prepack": "bun run build",
     "test": "vitest run",
     "test:watch": "vitest",
diff --git a/scripts/build.mjs b/scripts/build.mjs
new file mode 100644
index 0000000..cb900cf
--- /dev/null
+++ b/scripts/build.mjs
@@ -0,0 +1,23 @@
+import { cp, rm } from 'node:fs/promises';
+import { spawn } from 'node:child_process';
+
+await rm('dist', { force: true, recursive: true });
+await run(process.execPath, ['./node_modules/typescript/bin/tsc', '-p', 'tsconfig.build.json']);
+await cp('src/command', 'dist/command', { recursive: true });
+
+function run(command, args) {
+  return new Promise((resolve, reject) => {
+    const child = spawn(command, args, {
+      stdio: 'inherit',
+    });
+    child.on('error', reject);
+    child.on('close', (code) => {
+      if (code === 0) {
+        resolve();
+        return;
+      }
+
+      reject(new Error(`${command} ${args.join(' ')} exited with code ${code ?? 1}`));
+    });
+  });
+}
diff --git a/src/sync/paths.ts b/src/sync/paths.ts
index 54bd147..028eb7e 100644
--- a/src/sync/paths.ts
+++ b/src/sync/paths.ts
@@ -60,6 +60,16 @@ const MODEL_FAVORITES_FILE = 'model.json';
 const SKILLS_DIR = 'skills';
 const HOME_AGENTS_DIR = '.agents';
 
+function pathForPlatform(platform: NodeJS.Platform): path.PlatformPath {
+  return platform === 'win32' ? path.win32 : path.posix;
+}
+
+export function pathForLocations(locations: SyncLocations): path.PlatformPath {
+  return locations.xdg.homeDir.includes('\\') || /^[a-zA-Z]:/.test(locations.xdg.homeDir)
+    ? path.win32
+    : path.posix;
+}
+
 export function resolveHomeDir(
   env: NodeJS.ProcessEnv = process.env,
   platform: NodeJS.Platform = process.platform
@@ -87,16 +97,18 @@ export function resolveXdgPaths(
   }
 
   if (platform === 'win32') {
-    const configDir = env.APPDATA ?? path.join(homeDir, 'AppData', 'Roaming');
-    const dataDir = env.LOCALAPPDATA ?? path.join(homeDir, 'AppData', 'Local');
+    const pathApi = pathForPlatform(platform);
+    const configDir = env.APPDATA ?? pathApi.join(homeDir, 'AppData', 'Roaming');
+    const dataDir = env.LOCALAPPDATA ?? pathApi.join(homeDir, 'AppData', 'Local');
     // Windows doesn't have XDG_STATE_HOME equivalent, use LOCALAPPDATA
-    const stateDir = env.LOCALAPPDATA ?? path.join(homeDir, 'AppData', 'Local');
+    const stateDir = env.LOCALAPPDATA ?? pathApi.join(homeDir, 'AppData', 'Local');
     return { homeDir, configDir, dataDir, stateDir };
   }
 
-  const configDir = env.XDG_CONFIG_HOME ?? path.join(homeDir, '.config');
-  const dataDir = env.XDG_DATA_HOME ?? path.join(homeDir, '.local', 'share');
-  const stateDir = env.XDG_STATE_HOME ?? path.join(homeDir, '.local', 'state');
+  const pathApi = pathForPlatform(platform);
+  const configDir = env.XDG_CONFIG_HOME ?? pathApi.join(homeDir, '.config');
+  const dataDir = env.XDG_DATA_HOME ?? pathApi.join(homeDir, '.local', 'share');
+  const stateDir = env.XDG_STATE_HOME ?? pathApi.join(homeDir, '.local', 'state');
 
   return { homeDir, configDir, dataDir, stateDir };
 }
@@ -107,26 +119,31 @@ export function resolveSyncLocations(
 ): SyncLocations {
   const xdg = resolveXdgPaths(env, platform);
   const customConfigDir = env.opencode_config_dir;
+  const pathApi = pathForPlatform(platform);
   const configRoot = customConfigDir
-    ? path.resolve(expandHome(customConfigDir, xdg.homeDir))
-    : path.join(xdg.configDir, 'opencode');
-  const dataRoot = path.join(xdg.dataDir, 'opencode');
+    ? pathApi.resolve(expandHome(customConfigDir, xdg.homeDir, platform))
+    : pathApi.join(xdg.configDir, 'opencode');
+  const dataRoot = pathApi.join(xdg.dataDir, 'opencode');
 
   return {
     xdg,
     configRoot,
-    syncConfigPath: path.join(configRoot, DEFAULT_SYNC_CONFIG_NAME),
-    overridesPath: path.join(configRoot, DEFAULT_OVERRIDES_NAME),
-    statePath: path.join(dataRoot, DEFAULT_STATE_NAME),
-    defaultRepoDir: path.join(dataRoot, 'opencode-synced', 'repo'),
+    syncConfigPath: pathApi.join(configRoot, DEFAULT_SYNC_CONFIG_NAME),
+    overridesPath: pathApi.join(configRoot, DEFAULT_OVERRIDES_NAME),
+    statePath: pathApi.join(dataRoot, DEFAULT_STATE_NAME),
+    defaultRepoDir: pathApi.join(dataRoot, 'opencode-synced', 'repo'),
   };
 }
 
-export function expandHome(inputPath: string, homeDir: string): string {
+export function expandHome(
+  inputPath: string,
+  homeDir: string,
+  platform: NodeJS.Platform = process.platform
+): string {
   if (!inputPath) return inputPath;
   if (!homeDir) return inputPath;
   if (inputPath === '~') return homeDir;
-  if (inputPath.startsWith('~/')) return path.join(homeDir, inputPath.slice(2));
+  if (inputPath.startsWith('~/') || inputPath.startsWith('~\\')) return pathForPlatform(platform).join(homeDir, inputPath.slice(2));
   return inputPath;
 }
 
@@ -135,8 +152,9 @@ export function normalizePath(
   homeDir: string,
   platform: NodeJS.Platform = process.platform
 ): string {
-  const expanded = expandHome(inputPath, homeDir);
-  const resolved = path.resolve(expanded);
+  const pathApi = pathForPlatform(platform);
+  const expanded = expandHome(inputPath, homeDir, platform);
+  const resolved = pathApi.resolve(expanded);
   if (platform === 'win32') {
     return resolved.toLowerCase();
   }
@@ -177,26 +195,27 @@ export function buildSyncPlan(
   platform: NodeJS.Platform = process.platform
 ): SyncPlan {
   const configRoot = locations.configRoot;
-  const dataRoot = path.join(locations.xdg.dataDir, 'opencode');
-  const stateRoot = path.join(locations.xdg.stateDir, 'opencode');
-  const repoConfigRoot = path.join(repoRoot, 'config');
-  const repoDataRoot = path.join(repoRoot, 'data');
-  const repoSecretsRoot = path.join(repoRoot, 'secrets');
-  const repoStateRoot = path.join(repoRoot, 'state');
-  const repoExtraDir = path.join(repoSecretsRoot, 'extra');
-  const manifestPath = path.join(repoSecretsRoot, 'extra-manifest.json');
-  const repoConfigExtraDir = path.join(repoConfigRoot, 'extra');
-  const configManifestPath = path.join(repoConfigRoot, 'extra-manifest.json');
+  const pathApi = pathForPlatform(platform);
+  const dataRoot = pathApi.join(locations.xdg.dataDir, 'opencode');
+  const stateRoot = pathApi.join(locations.xdg.stateDir, 'opencode');
+  const repoConfigRoot = pathApi.join(repoRoot, 'config');
+  const repoDataRoot = pathApi.join(repoRoot, 'data');
+  const repoSecretsRoot = pathApi.join(repoRoot, 'secrets');
+  const repoStateRoot = pathApi.join(repoRoot, 'state');
+  const repoExtraDir = pathApi.join(repoSecretsRoot, 'extra');
+  const manifestPath = pathApi.join(repoSecretsRoot, 'extra-manifest.json');
+  const repoConfigExtraDir = pathApi.join(repoConfigRoot, 'extra');
+  const configManifestPath = pathApi.join(repoConfigRoot, 'extra-manifest.json');
 
   const items: SyncItem[] = [];
   const usingSecretsBackend = hasSecretsBackend(config);
-  const authJsonPath = path.join(dataRoot, 'auth.json');
-  const mcpAuthJsonPath = path.join(dataRoot, 'mcp-auth.json');
+  const authJsonPath = pathApi.join(dataRoot, 'auth.json');
+  const mcpAuthJsonPath = pathApi.join(dataRoot, 'mcp-auth.json');
 
   const addFile = (name: string, isSecret: boolean, isConfigFile: boolean): void => {
     items.push({
-      localPath: path.join(configRoot, name),
-      repoPath: path.join(repoConfigRoot, name),
+      localPath: pathApi.join(configRoot, name),
+      repoPath: pathApi.join(repoConfigRoot, name),
       type: 'file',
       isSecret,
       isConfigFile,
@@ -210,8 +229,8 @@ export function buildSyncPlan(
 
   for (const dirName of CONFIG_DIRS) {
     items.push({
-      localPath: path.join(configRoot, dirName),
-      repoPath: path.join(repoConfigRoot, dirName),
+      localPath: pathApi.join(configRoot, dirName),
+      repoPath: pathApi.join(repoConfigRoot, dirName),
       type: 'dir',
       isSecret: false,
       isConfigFile: false,
@@ -220,8 +239,8 @@ export function buildSyncPlan(
 
   if (config.includeOpencodeSkills !== false) {
     items.push({
-      localPath: path.join(configRoot, SKILLS_DIR),
-      repoPath: path.join(repoConfigRoot, SKILLS_DIR),
+      localPath: pathApi.join(configRoot, SKILLS_DIR),
+      repoPath: pathApi.join(repoConfigRoot, SKILLS_DIR),
       type: 'dir',
       isSecret: false,
       isConfigFile: false,
@@ -230,8 +249,8 @@ export function buildSyncPlan(
 
   if (config.includeAgentsDir !== false) {
     items.push({
-      localPath: path.join(locations.xdg.homeDir, HOME_AGENTS_DIR),
-      repoPath: path.join(repoConfigRoot, HOME_AGENTS_DIR),
+      localPath: pathApi.join(locations.xdg.homeDir, HOME_AGENTS_DIR),
+      repoPath: pathApi.join(repoConfigRoot, HOME_AGENTS_DIR),
       type: 'dir',
       isSecret: false,
       isConfigFile: false,
@@ -240,8 +259,8 @@ export function buildSyncPlan(
 
   if (config.includeModelFavorites !== false) {
     items.push({
-      localPath: path.join(stateRoot, MODEL_FAVORITES_FILE),
-      repoPath: path.join(repoStateRoot, MODEL_FAVORITES_FILE),
+      localPath: pathApi.join(stateRoot, MODEL_FAVORITES_FILE),
+      repoPath: pathApi.join(repoStateRoot, MODEL_FAVORITES_FILE),
       type: 'file',
       isSecret: false,
       isConfigFile: false,
@@ -253,14 +272,14 @@ export function buildSyncPlan(
       items.push(
         {
           localPath: authJsonPath,
-          repoPath: path.join(repoDataRoot, 'auth.json'),
+          repoPath: pathApi.join(repoDataRoot, 'auth.json'),
           type: 'file',
           isSecret: true,
           isConfigFile: false,
         },
         {
           localPath: mcpAuthJsonPath,
-          repoPath: path.join(repoDataRoot, 'mcp-auth.json'),
+          repoPath: pathApi.join(repoDataRoot, 'mcp-auth.json'),
           type: 'file',
           isSecret: true,
           isConfigFile: false,
@@ -270,8 +289,8 @@ export function buildSyncPlan(
 
     if (config.includeSessions && !isTursoSessionBackend(config)) {
       items.push({
-        localPath: path.join(dataRoot, SESSION_DB_FILE),
-        repoPath: path.join(repoDataRoot, SESSION_DB_FILE),
+        localPath: pathApi.join(dataRoot, SESSION_DB_FILE),
+        repoPath: pathApi.join(repoDataRoot, SESSION_DB_FILE),
         type: 'file',
         isSecret: true,
         isConfigFile: false,
@@ -280,8 +299,8 @@ export function buildSyncPlan(
 
       for (const dirName of SESSION_DIRS) {
         items.push({
-          localPath: path.join(dataRoot, dirName),
-          repoPath: path.join(repoDataRoot, dirName),
+          localPath: pathApi.join(dataRoot, dirName),
+          repoPath: pathApi.join(repoDataRoot, dirName),
           type: 'dir',
           isSecret: true,
           isConfigFile: false,
@@ -293,8 +312,8 @@ export function buildSyncPlan(
     if (config.includePromptStash) {
       for (const fileName of PROMPT_STASH_FILES) {
         items.push({
-          localPath: path.join(stateRoot, fileName),
-          repoPath: path.join(repoStateRoot, fileName),
+          localPath: pathApi.join(stateRoot, fileName),
+          repoPath: pathApi.join(repoStateRoot, fileName),
           type: 'file',
           isSecret: true,
           isConfigFile: false,
@@ -356,7 +375,7 @@ function buildExtraPathPlan(
 
   const entries = allowlist.map((sourcePath) => ({
     sourcePath,
-    repoPath: path.join(repoExtraDir, encodeExtraPath(sourcePath)),
+    repoPath: pathForPlatform(platform).join(repoExtraDir, encodeExtraPath(sourcePath)),
   }));
 
   return {
diff --git a/src/sync/turso.ts b/src/sync/turso.ts
index 678b59f..c3970ce 100644
--- a/src/sync/turso.ts
+++ b/src/sync/turso.ts
@@ -6,7 +6,7 @@ import path from 'node:path';
 import type { NormalizedSyncConfig } from './config.js';
 import { isPlainObject, isTursoSessionBackend, pathExists, writeJsonFile } from './config.js';
 import { SyncCommandError } from './errors.js';
-import type { SyncLocations } from './paths.js';
+import { pathForLocations, type SyncLocations } from './paths.js';
 
 const SESSION_SYNC_TABLE = 'opencode_session_sync_snapshot';
 const CREDENTIAL_VERSION = 1;
@@ -560,7 +560,12 @@ export function createTursoSessionBackend(options: {
 }
 
 export function resolveTursoCredentialPath(locations: SyncLocations): string {
-  return path.join(locations.xdg.dataDir, 'opencode', 'opencode-synced', 'turso-session.json');
+  return pathForLocations(locations).join(
+    locations.xdg.dataDir,
+    'opencode',
+    'opencode-synced',
+    'turso-session.json'
+  );
 }
 
 export function resolveSessionDbPaths(locations: SyncLocations): {
@@ -568,8 +573,11 @@ export function resolveSessionDbPaths(locations: SyncLocations): {
   walPath: string;
   shmPath: string;
 } {
-  const dataRoot = path.join(locations.xdg.dataDir, 'opencode');
-  const dbPath = path.join(dataRoot, 'opencode.db');
+  const dbPath = pathForLocations(locations).join(
+    locations.xdg.dataDir,
+    'opencode',
+    'opencode.db'
+  );
   return {
     dbPath,
     walPath: `${dbPath}-wal`,