Add CI, release workflow, and Homebrew distribution (#1)

* Add CI, release workflow, Homebrew distribution, and fix --help

- GitHub Actions CI: build + test on push/PR to main
- Release workflow: build binary, create GitHub Release, update Homebrew tap
- Homebrew formula generator script (obj-p/homebrew-tap)
- README: add brew install instructions
- Fix --help printing raw error by routing HelpCommand through non-NSApp path

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

* Use Xcode 26.3 in CI and release workflows

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

---------

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

Author: obj-p

.github/workflows/ci.yml

@@ -0,0 +1,22 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  build-and-test:
+    runs-on: macos-15
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Select Xcode
+        run: sudo xcode-select -s /Applications/Xcode_26.3.app
+
+      - name: Build
+        run: swift build
+
+      - name: Test
+        run: swift test --filter "PreviewsCoreTests"

.github/workflows/release.yml

@@ -0,0 +1,81 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+permissions:
+  contents: write
+
+jobs:
+  build:
+    runs-on: macos-15
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Select Xcode
+        run: sudo xcode-select -s /Applications/Xcode_26.3.app
+
+      - name: Get version from tag
+        id: version
+        run: |
+          VERSION=${GITHUB_REF#refs/tags/v}
+          echo "VERSION=$VERSION" >> "$GITHUB_OUTPUT"
+
+      - name: Build release binary
+        run: swift build -c release
+
+      - name: Package binary
+        env:
+          VERSION: ${{ steps.version.outputs.VERSION }}
+        run: |
+          STAGING="previewsmcp-${VERSION}-darwin-arm64"
+          mkdir -p "$STAGING"
+          cp .build/release/previewsmcp "$STAGING/"
+          cp LICENSE "$STAGING/"
+          cp README.md "$STAGING/"
+          tar -czf "${STAGING}.tar.gz" "$STAGING"
+          shasum -a 256 "${STAGING}.tar.gz" > "${STAGING}.tar.gz.sha256"
+
+      - name: Create GitHub Release
+        env:
+          GH_TOKEN: ${{ github.token }}
+          VERSION: ${{ steps.version.outputs.VERSION }}
+        run: |
+          STAGING="previewsmcp-${VERSION}-darwin-arm64"
+          gh release create "v${VERSION}" \
+            "${STAGING}.tar.gz" \
+            "${STAGING}.tar.gz.sha256" \
+            --title "v${VERSION}" \
+            --generate-notes
+
+      - name: Update Homebrew tap
+        env:
+          VERSION: ${{ steps.version.outputs.VERSION }}
+          HOMEBREW_TAP_TOKEN: ${{ secrets.HOMEBREW_TAP_TOKEN }}
+        run: |
+          if [ -z "$HOMEBREW_TAP_TOKEN" ]; then
+            echo "HOMEBREW_TAP_TOKEN not set, skipping Homebrew tap update"
+            exit 0
+          fi
+
+          STAGING="previewsmcp-${VERSION}-darwin-arm64"
+          SHA256="$(awk '{print $1}' "${STAGING}.tar.gz.sha256")"
+          URL="https://github.com/obj-p/PreviewsMCP/releases/download/v${VERSION}/${STAGING}.tar.gz"
+
+          bash scripts/generate-formula.sh "$VERSION" "$URL" "$SHA256" > previewsmcp.rb
+
+          git clone "https://x-access-token:${HOMEBREW_TAP_TOKEN}@github.com/obj-p/homebrew-tap.git" tap-repo
+          mkdir -p tap-repo/Formula
+          cp previewsmcp.rb tap-repo/Formula/previewsmcp.rb
+          cd tap-repo
+          git config user.name "github-actions[bot]"
+          git config user.email "github-actions[bot]@users.noreply.github.com"
+          git add Formula/previewsmcp.rb
+          if git diff --cached --quiet; then
+            echo "Formula already up to date"
+            exit 0
+          fi
+          git commit -m "previewsmcp ${VERSION}"
+          git push origin main

README.md

@@ -13,6 +13,13 @@ Render and interact with SwiftUI previews outside of Xcode. Works as a CLI tool
 
 ## Installation
 
+### Homebrew
+
+```bash
+brew tap obj-p/tap
+brew install previewsmcp
+```
+
 ### From source
 
 ```bash

Sources/PreviewsCLI/PreviewsMCPApp.swift

@@ -18,8 +18,8 @@ struct PreviewsMCPApp {
             PreviewsMCPCommand.exit(withError: error)
         }
 
-        // ListCommand doesn't need NSApplication
-        if command is ListCommand {
+        // Commands that don't need NSApplication (list, help, etc.)
+        if command is ListCommand || !(command is RunCommand || command is ServeCommand || command is SnapshotCommand) {
             do {
                 var mutable = command
                 try mutable.run()
@@ -45,8 +45,7 @@ struct PreviewsMCPApp {
                     var mutable = command
                     try mutable.run()
                 } catch {
-                    print("Error: \(error)")
-                    NSApp.terminate(nil)
+                    PreviewsMCPCommand.exit(withError: error)
                 }
             }
         }

scripts/generate-formula.sh

@@ -0,0 +1,37 @@
+#!/bin/bash
+# Generates a Homebrew formula for previewsmcp
+# Usage: generate-formula.sh <version> <url> <sha256>
+set -euo pipefail
+
+VERSION="$1"
+URL="$2"
+SHA256="$3"
+
+cat <<EOF
+class Previewsmcp < Formula
+  desc "SwiftUI preview renderer with MCP server for AI-driven UI development"
+  homepage "https://github.com/obj-p/PreviewsMCP"
+  license "MIT"
+  version "${VERSION}"
+
+  url "${URL}"
+  sha256 "${SHA256}"
+
+  depends_on :macos
+
+  def install
+    bin.install "previewsmcp"
+  end
+
+  def caveats
+    <<~EOS
+      previewsmcp requires Xcode 16+ to compile SwiftUI previews at runtime.
+      For iOS simulator support, Apple Silicon is required.
+    EOS
+  end
+
+  test do
+    assert_match "SwiftUI previews", shell_output("#{bin}/previewsmcp --help")
+  end
+end
+EOF