docs: add CLAUDE.md for project guidance

- Introduced CLAUDE.md to provide comprehensive guidance on the macOS Emacs building system, including project overview, common commands, architecture details, and testing instructions.

.github/.release-please-manifest.json

@@ -1,3 +1,3 @@
 {
-  ".": "0.6.62"
+  ".": "0.6.63"
 }

CHANGELOG.md

@@ -1,5 +1,13 @@
 # Changelog
 
+## [0.6.63](https://github.com/jimeh/build-emacs-for-macos/compare/v0.6.62...v0.6.63) (2025-09-14)
+
+
+### Features
+
+* **icon:** add support for custom application icons via --icon-uri option ([607076a](https://github.com/jimeh/build-emacs-for-macos/commit/607076a91bf0f227d16c9404f01a64144290685a))
+* **icon:** add support for Tahoe icons with --tahoe-icon-uri and --tahoe-icon-name options ([b5ed388](https://github.com/jimeh/build-emacs-for-macos/commit/b5ed3887c172540de4a6190072b1e15f5d5efe2c))
+
 ## [0.6.62](https://github.com/jimeh/build-emacs-for-macos/compare/v0.6.61...v0.6.62) (2025-09-14)
 
 

CLAUDE.md

@@ -0,0 +1,80 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with
+code in this repository.
+
+## Project Overview
+
+macOS Emacs building system with Ruby and Go components:
+
+- **Ruby script** (`build-emacs-for-macos`): Main build script for creating
+  self-contained Emacs.app bundles
+- **Go CLI tool** (`emacs-builder`): Packaging, signing, notarization, and
+  release management
+- **Dual dependency management**: Nix (preferred) or Homebrew
+
+## Common Commands
+
+```bash
+# Environment setup (Nix preferred)
+nix develop                       # Default macOS 11 SDK
+nix develop .#macos{11-15,26}     # Target specific SDK version
+
+# Go development
+make build                        # Build emacs-builder CLI
+make test                         # Run tests with race detection
+make lint                         # Run golangci-lint
+make format                       # Format with gofumpt
+
+# Ruby development
+bundle exec rubocop               # Lint (with development group)
+
+# Build Emacs
+./build-emacs-for-macos           # Build from master
+./build-emacs-for-macos emacs-29.4
+```
+
+## Architecture
+
+### Ruby Build Script (`build-emacs-for-macos`)
+
+Single-file Ruby script (~2500 lines) that:
+
+- Downloads source tarballs from emacs-mirror/emacs on GitHub
+- Configures and compiles Emacs with native-comp, tree-sitter support
+- Creates self-contained .app bundles by embedding/relinking dependencies
+- Uses `ruby-macho` gem for Mach-O binary manipulation (RPATH handling)
+
+### Go CLI (`cmd/emacs-builder/`)
+
+Uses `urfave/cli/v2` framework. Key packages in `pkg/`:
+
+- `cli/`: Commands (plan, sign, sign-files, notarize, package, release, cask)
+- `sign/`: macOS code signing via `codesign`
+- `notarize/`: Apple notarization workflow via `notarytool`
+- `release/`: GitHub release management
+- `dmgbuild/`: DMG creation using Python dmgbuild
+- `plan/`: Build plan JSON parsing and management
+
+### Nix Environment (`flake.nix`)
+
+- Multi-SDK support: macOS 11-15, 26 via `.#macos{11,12,13,14,15,26}`
+- Excludes ncurses intentionally (links against system version for TUI)
+- Sets `MACOSX_DEPLOYMENT_TARGET`, `DEVELOPER_DIR`, `NIX_LIBGCCJIT_*`
+
+## Testing
+
+```bash
+make test                         # All Go tests
+go test ./pkg/release/...         # Single package
+go test -run TestName ./pkg/...   # Single test
+```
+
+Tests use `_test.go` suffix alongside source files.
+
+## Working Directories
+
+- `sources/`: Downloaded/extracted Emacs source (gitignored)
+- `builds/`: Build outputs and .app bundles (gitignored)
+- `patches/`: Emacs patches applied during build
+- `bin/`: Built Go binaries (gitignored)

Makefile

@@ -141,10 +141,10 @@ nix-flake-update:
 
 .SILENT: flake-package-versions
 flake-package-versions:
-	nix develop --command -- bash -c \
+	nix develop --command bash -c \
 		'nix derivation show \
 			$$(echo $$PATH | tr ":" "\n" | grep "/nix/store" | sort -u) \
-			| jq -r ".[].name" | sort -u'
+			| jq -r ".derivations[].name" | sort -u'
 
 flake.pkgs: flake.nix flake.lock
 	$(MAKE) flake-package-versions > "$@"

README.md

@@ -141,7 +141,7 @@ Options:
         --[no-]relink-eln-files      Enable/disable re-linking shared libraries in bundled *.eln files (default: enabled)
         --[no-]rsvg                  Enable/disable SVG image support via librsvg (default: enabled)
         --[no-]dbus                  Enable/disable dbus support (default: enabled)
-        --[no-]alpha-background      Enable/disable experimental alpha-background patch when building Emacs 30.x - 31.x (default: disabled)
+        --alpha-background           Apply experimental alpha-background patch when building Emacs 30.x - 31.x (default: disabled)
         --no-frame-refocus           Apply no-frame-refocus patch when building Emacs 27.x - 31.x (default: disabled)
         --no-titlebar                Apply no-titlebar patch when building Emacs 27.x - 28.x (default: disabled)
         --[no-]xwidgets              Enable/disable XWidgets when building Emacs 27.x (default: disabled)
@@ -155,6 +155,9 @@ Options:
     -o, --output DIR                 Output directory for finished builds (default: <work-dir>/builds)
         --build-name NAME            Override generated build name
         --dist-include x,y,z         List of extra files to copy from Emacs source into build folder/archive (default: COPYING)
+        --icon-uri URI               Local path or URL to a .icns file to replace the default app icon
+        --tahoe-icon-uri URI         Local path or URL to an Assets.car file for macOS 26 icons. Requires --tahoe-icon-name.
+        --tahoe-icon-name NAME       Name of the icon in Assets.car to set as CFBundleIconName
         --[no-]self-sign             Enable/disable self-signing of Emacs.app (default: enabled)
         --[no-]archive               Enable/disable creating *.tbz archive (default: enabled)
         --[no-]archive-keep-build-dir

build-emacs-for-macos

@@ -229,6 +229,14 @@ class Build
 
     handle_native_lisp(app)
 
+    if options[:icon_uri] || options[:tahoe_icon_uri] || options[:tahoe_icon_name]
+      IconEmbedder.new(
+        app,
+        icon_uri: options[:icon_uri],
+        tahoe_icon_uri: options[:tahoe_icon_uri],
+        tahoe_icon_name: options[:tahoe_icon_name]
+      ).embed
+    end
     CLIHelperEmbedder.new(app).embed
     CSourcesEmbedder.new(app, @source_dir).embed
     LibEmbedder.new(
@@ -1413,6 +1421,98 @@ class CSourcesEmbedder < AbstractEmbedder
   end
 end
 
+class IconEmbedder < AbstractEmbedder
+  include Helpers
+
+  def initialize(app, icon_uri: nil, tahoe_icon_uri: nil, tahoe_icon_name: nil)
+    super(app)
+    @icon_uri = icon_uri
+    @tahoe_icon_uri = tahoe_icon_uri
+    @tahoe_icon_name = tahoe_icon_name
+  end
+
+  def embed
+    handle_icns if present?(@icon_uri)
+    handle_tahoe if present?(@tahoe_icon_uri)
+  ensure
+    cleanup_tmpdir
+  end
+
+  private
+
+  def present?(val)
+    !val.nil? && !val.strip.empty?
+  end
+
+  def handle_icns
+    source = resolve_source(@icon_uri, '.icns', 'icon.icns')
+    target = File.join(resources_dir, 'Emacs.icns')
+    info 'Replacing application icon (Emacs.icns)...'
+    run_cmd('cp', '-pRL', source, target)
+    source
+  end
+
+  def handle_tahoe
+    fatal '--tahoe-icon-name is required with --tahoe-icon-uri' \
+      unless present?(@tahoe_icon_name)
+
+    source = resolve_source(@tahoe_icon_uri, '.car', 'Assets.car')
+    target = File.join(resources_dir, 'Assets.car')
+    info 'Placing Tahoe Assets.car into Resources...'
+    run_cmd('cp', '-pRL', source, target)
+
+    set_cf_bundle_icon_name(@tahoe_icon_name)
+    source
+  end
+
+  def set_cf_bundle_icon_name(name)
+    info 'Setting CFBundleIconName in Info.plist...'
+    info_plist = File.join(app, 'Contents', 'Info.plist')
+    fatal "Info.plist not found: #{info_plist}" unless File.exist?(info_plist)
+
+    # Use plutil which adds/replaces the key as needed
+    run_cmd(
+      'plutil', '-replace', 'CFBundleIconName', '-string',
+      name, info_plist
+    )
+  end
+
+  def resolve_source(uri, expected_ext, download_name)
+    file_path = if valid_url?(uri)
+                  download_file(uri, download_name)
+                else
+                  local = File.expand_path(uri)
+                  unless File.exist?(local)
+                    fatal "File does not exist: #{local}"
+                  end
+                  local
+                end
+
+    ext = File.extname(file_path).downcase
+    fatal "Unexpected file type: #{ext} (expected #{expected_ext})" \
+      unless ext == expected_ext
+
+    file_path
+  end
+
+  def tmpdir
+    @tmpdir ||= Dir.mktmpdir(%w[emacs-assets .tmp])
+  end
+
+  def download_file(url, name)
+    path = File.join(tmpdir, name)
+    info "Downloading asset from: #{url}"
+    run_cmd('curl', '-L#', url, '-o', path)
+    path
+  end
+
+  def cleanup_tmpdir
+    return unless @tmpdir
+
+    FileUtils.rm_rf(@tmpdir)
+  end
+end
+
 class LibEmbedder < AbstractEmbedder
   attr_reader :lib_sources
   attr_reader :extra_libs
@@ -1907,7 +2007,7 @@ class GccInfo
   def clean_macho_binary(path)
     debug "Checking for duplicate RPATHs in #{path}"
     macho_cleaner = MachOCleaner.new(path)
-    return unless macho_cleaner.has_duplicate_rpaths?
+    return unless macho_cleaner.duplicate_rpaths?
 
     begin
       info "Removing duplicate RPATHs from #{path}"
@@ -1971,7 +2071,7 @@ class MachOCleaner
   end
 
   # Check if file has duplicate RPATH commands
-  def has_duplicate_rpaths?
+  def duplicate_rpaths?
     count_duplicate_rpaths(macho_object).positive?
   end
 
@@ -2101,6 +2201,14 @@ class CLIOptions
 
   def parse!(args)
     parser.parse!(args)
+
+    if options[:tahoe_icon_uri] &&
+       (
+         options[:tahoe_icon_name].nil? ||
+         options[:tahoe_icon_name].strip.empty?
+       )
+      fatal '--tahoe-icon-name is required when --tahoe-icon-uri is specified'
+    end
   rescue OptionParser::InvalidOption => e
     fatal e.message
   end
@@ -2127,6 +2235,9 @@ class CLIOptions
       github_src_repo: nil,
       github_auth: true,
       dist_include: ['COPYING', 'configure_output.txt'],
+      icon_uri: nil,
+      tahoe_icon_uri: nil,
+      tahoe_icon_name: nil,
       self_sign: true,
       archive: true,
       archive_keep: false,
@@ -2323,6 +2434,22 @@ class CLIOptions
         'folder/archive (default: COPYING)'
       ) { |v| options[:dist_include] = v }
 
+      opts.on(
+        '--icon-uri URI',
+        'Local path or URL to a .icns file to replace the default app icon'
+      ) { |v| options[:icon_uri] = v }
+
+      opts.on(
+        '--tahoe-icon-uri URI',
+        'Local path or URL to an Assets.car file for macOS 26 icons. ' \
+        'Requires --tahoe-icon-name.'
+      ) { |v| options[:tahoe_icon_uri] = v }
+
+      opts.on(
+        '--tahoe-icon-name NAME',
+        'Name of the icon in Assets.car to set as CFBundleIconName'
+      ) { |v| options[:tahoe_icon_name] = v }
+
       opts.on(
         '--[no-]self-sign',
         'Enable/disable self-signing of Emacs.app (default: enabled)'
@@ -2372,7 +2499,7 @@ if __FILE__ == $PROGRAM_NAME
     elsif cli_options[:clean_macho_binary]
       macho_cleaner = MachOCleaner.new(cli_options[:clean_macho_binary])
 
-      if macho_cleaner.has_duplicate_rpaths?
+      if macho_cleaner.duplicate_rpaths?
         build.info 'Removing duplicate RPATHs from ' \
                    "#{cli_options[:clean_macho_binary]}..."
         macho_cleaner.clean!

flake.lock

@@ -20,11 +20,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1757545623,
+        "lastModified": 1767313136,
-        "narHash": "sha256-mCxPABZ6jRjUQx3bPP4vjA68ETbPLNz9V2pk9tO7pRQ=",
+        "narHash": "sha256-16KkgfdYqjaeRGBaYsNrhPRRENs0qzkQVUooNHtoy2w=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "8cd5ce828d5d1d16feff37340171a98fc3bf6526",
+        "rev": "ac62194c3917d5f474c1a844b6fd6da2db95077d",
         "type": "github"
       },
       "original": {

flake.nix

@@ -6,16 +6,32 @@
     flake-utils.url = "github:numtide/flake-utils";
   };
 
-  outputs = { self, nixpkgs, flake-utils }:
+  outputs =
-    flake-utils.lib.eachDefaultSystem (system:
+    {
+      self,
+      nixpkgs,
+      flake-utils,
+    }:
+    flake-utils.lib.eachDefaultSystem (
+      system:
       let
         pkgs = nixpkgs.legacyPackages.${system};
 
         # List of supported macOS SDK versions.
-        sdk_versions = [ "11" "12" "13" "14" "15" ];
+        sdk_versions = [
+          "11"
+          "12"
+          "13"
+          "14"
+          "15"
+          "26"
+        ];
         default_sdk_version = "11";
 
-        mkDevShell = { macos_version ? default_sdk_version }:
+        mkDevShell =
+          {
+            macos_version ? default_sdk_version,
+          }:
           let
             apple_sdk = pkgs.${"apple-sdk_${macos_version}"};
           in

flake.pkgs

@@ -13,7 +13,7 @@ coreutils-9.7
 curl-8.14.1
 dbus-1.14.10
 diffutils-3.12
-expat-2.7.1
+expat-2.7.3
 file-5.45
 findutils-4.10.0
 fontconfig-2.16.0
@@ -53,7 +53,7 @@ libxml2-2.13.8
 mailutils-3.18
 nettle-3.10.1
 nghttp2-1.65.0
-openssl-3.4.2
+openssl-3.4.3
 patch-2.7.6
 pkg-config-wrapper-0.29.2
 python3-3.13.5