feat: add linux-musl (Alpine) builds for x64 and arm64 (#784)

* feat: add linux-musl (Alpine) builds for x64 and arm64

Add x86_64-unknown-linux-musl and aarch64-unknown-linux-musl targets to
the release workflow using cargo-zigbuild. Update the JS wrapper and
postinstall script to detect musl libc and select the correct binary.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: simplify isMusl() and add musl targets to build script

Address PR #784 review feedback:
- Remove redundant first try block in isMusl() (ldd --version always
  throws on musl, so only the `|| true` variant works)
- Add x86_64-unknown-linux-musl and aarch64-unknown-linux-musl targets
  to build-all-platforms.sh to stay in sync with the release workflow

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/release.yml

@@ -31,6 +31,16 @@ jobs:
             target: aarch64-unknown-linux-gnu
             binary: agent-browser-linux-arm64
             use_zigbuild: true
+          - name: Linux musl x64
+            os: ubuntu-latest
+            target: x86_64-unknown-linux-musl
+            binary: agent-browser-linux-musl-x64
+            use_zigbuild: true
+          - name: Linux musl ARM64
+            os: ubuntu-latest
+            target: aarch64-unknown-linux-musl
+            binary: agent-browser-linux-musl-arm64
+            use_zigbuild: true
           - name: Windows x64
             os: ubuntu-latest
             target: x86_64-pc-windows-gnu
@@ -175,6 +185,8 @@ jobs:
           EXPECTED_BINARIES=(
             "agent-browser-linux-x64"
             "agent-browser-linux-arm64"
+            "agent-browser-linux-musl-x64"
+            "agent-browser-linux-musl-arm64"
             "agent-browser-win32-x64.exe"
             "agent-browser-darwin-x64"
             "agent-browser-darwin-arm64"
@@ -199,7 +211,7 @@ jobs:
             echo "Error: $ERRORS binary issues found"
             exit 1
           fi
-          echo "All 5 platform binaries present and valid"
+          echo "All 7 platform binaries present and valid"
 
       - name: Create Release Pull Request or Publish to npm
         id: changesets
@@ -241,8 +253,8 @@ jobs:
       - name: Verify binaries exist
         run: |
           BINARY_COUNT=$(ls bin/agent-browser-* 2>/dev/null | wc -l)
-          if [ "$BINARY_COUNT" -lt 5 ]; then
-            echo "Error: Expected 5 binaries, found $BINARY_COUNT"
+          if [ "$BINARY_COUNT" -lt 7 ]; then
+            echo "Error: Expected 7 binaries, found $BINARY_COUNT"
             ls -la bin/
             exit 1
           fi

bin/agent-browser.js

@@ -8,7 +8,7 @@
  * binary directly (zero overhead).
  */
 
-import { spawn } from 'child_process';
+import { spawn, execSync } from 'child_process';
 import { existsSync, accessSync, chmodSync, constants } from 'fs';
 import { dirname, join } from 'path';
 import { fileURLToPath } from 'url';
@@ -16,6 +16,17 @@ import { platform, arch } from 'os';
 
 const __dirname = dirname(fileURLToPath(import.meta.url));
 
+// Detect if the system uses musl libc (e.g. Alpine Linux)
+function isMusl() {
+  if (platform() !== 'linux') return false;
+  try {
+    const result = execSync('ldd --version 2>&1 || true', { encoding: 'utf8' });
+    return result.toLowerCase().includes('musl');
+  } catch {
+    return existsSync('/lib/ld-musl-x86_64.so.1') || existsSync('/lib/ld-musl-aarch64.so.1');
+  }
+}
+
 // Map Node.js platform/arch to binary naming convention
 function getBinaryName() {
   const os = platform();
@@ -27,7 +38,7 @@ function getBinaryName() {
       osKey = 'darwin';
       break;
     case 'linux':
-      osKey = 'linux';
+      osKey = isMusl() ? 'linux-musl' : 'linux';
       break;
     case 'win32':
       osKey = 'win32';

scripts/build-all-platforms.sh

@@ -61,6 +61,12 @@ build_target "x86_64-apple-darwin" "agent-browser-darwin-x64"
 # macOS ARM64 (via zig for cross-compilation)
 build_target "aarch64-apple-darwin" "agent-browser-darwin-arm64"
 
+# Linux musl x64 (Alpine)
+build_target "x86_64-unknown-linux-musl" "agent-browser-linux-musl-x64"
+
+# Linux musl ARM64 (Alpine)
+build_target "aarch64-unknown-linux-musl" "agent-browser-linux-musl-arm64"
+
 echo ""
 echo -e "${GREEN}Build complete!${NC}"
 echo ""

scripts/postinstall.js

@@ -20,8 +20,20 @@ const __dirname = dirname(fileURLToPath(import.meta.url));
 const projectRoot = join(__dirname, '..');
 const binDir = join(projectRoot, 'bin');
 
+// Detect if the system uses musl libc (e.g. Alpine Linux)
+function isMusl() {
+  if (platform() !== 'linux') return false;
+  try {
+    const result = execSync('ldd --version 2>&1 || true', { encoding: 'utf8' });
+    return result.toLowerCase().includes('musl');
+  } catch {
+    return existsSync('/lib/ld-musl-x86_64.so.1') || existsSync('/lib/ld-musl-aarch64.so.1');
+  }
+}
+
 // Platform detection
-const platformKey = `${platform()}-${arch()}`;
+const osKey = platform() === 'linux' && isMusl() ? 'linux-musl' : platform();
+const platformKey = `${osKey}-${arch()}`;
 const ext = platform() === 'win32' ? '.exe' : '';
 const binaryName = `agent-browser-${platformKey}${ext}`;
 const binaryPath = join(binDir, binaryName);