Initial commit: Emacs major mode for LUMOS

- Implement lumos-mode.el with syntax highlighting and LSP integration
- Add smart indentation with configurable offset
- Create comprehensive test suite (14 tests)
- Set up GitHub Actions CI (Emacs 27.2, 28.2, 29.1, snapshot)
- Add MELPA recipe for package distribution
- Include dual licenses (MIT + Apache 2.0)
- Provide detailed README with installation and usage
- Document AI assistant context in CLAUDE.md

Features:
- Syntax highlighting for keywords, types, attributes, comments
- LSP integration via lsp-mode and lumos-lsp server
- Auto-completion, diagnostics, hover, go-to-definition
- Comment support (line and block)
- File type auto-detection for .lumos files
- Customizable variables and keybindings

Resolves #48

Author: rz1989s

.github/workflows/ci.yml

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+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        emacs_version:
+          - '27.2'
+          - '28.2'
+          - '29.1'
+          - 'snapshot'
+      fail-fast: false
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Emacs
+        uses: purcell/setup-emacs@master
+        with:
+          version: ${{ matrix.emacs_version }}
+
+      - name: Check Emacs version
+        run: emacs --version
+
+      - name: Run tests
+        run: make test
+
+      - name: Byte compile
+        run: make compile
+
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Emacs
+        uses: purcell/setup-emacs@master
+        with:
+          version: '29.1'
+
+      - name: Install package-lint
+        run: |
+          emacs -batch -l package \
+            --eval "(add-to-list 'package-archives '(\"melpa\" . \"https://melpa.org/packages/\") t)" \
+            --eval "(package-initialize)" \
+            --eval "(package-refresh-contents)" \
+            --eval "(package-install 'package-lint)"
+
+      - name: Run package-lint
+        run: |
+          emacs -batch -l package \
+            --eval "(add-to-list 'package-archives '(\"melpa\" . \"https://melpa.org/packages/\") t)" \
+            --eval "(package-initialize)" \
+            --eval "(require 'package-lint)" \
+            -f package-lint-batch-and-exit lumos-mode.el

.gitignore

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+*.elc
+*~
+*.bak
+.DS_Store

CLAUDE.md

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+# CLAUDE.md - lumos-mode
+
+**Repository**: https://github.com/getlumos/lumos-mode
+**Purpose**: Emacs major mode for LUMOS schema language
+
+---
+
+## Quick Reference
+
+For complete ecosystem context, see: **[lumos/CLAUDE.md](https://github.com/getlumos/lumos/blob/main/CLAUDE.md)**
+
+---
+
+## What is lumos-mode?
+
+Emacs major mode for editing `.lumos` files with syntax highlighting, smart indentation, and LSP integration via `lumos-lsp`.
+
+**Status**: v0.1.0 development
+**Target**: Emacs 26.1+
+**Dependencies**: lsp-mode (optional), lumos-lsp server
+
+---
+
+## Key Files
+
+| File | Purpose |
+|------|---------|
+| `lumos-mode.el` | Main mode implementation (syntax, indent, LSP) |
+| `lumos-mode-test.el` | Test suite (14 tests) |
+| `README.md` | Installation and usage guide |
+| `.github/workflows/ci.yml` | CI testing across Emacs 27.2, 28.2, 29.1, snapshot |
+| `Makefile` | Test and compile commands |
+| `lumos-mode-recipe.el` | MELPA recipe file |
+
+---
+
+## Features Implemented
+
+- ✅ Syntax highlighting (keywords, types, attributes, comments)
+- ✅ Smart indentation (context-aware, configurable offset)
+- ✅ LSP integration (auto-completion, diagnostics, hover, etc.)
+- ✅ Comment support (line and block)
+- ✅ File type auto-detection (`.lumos` → lumos-mode)
+- ✅ Customizable variables (indent-offset, lsp-server-command)
+- ✅ Test suite (14 tests covering mode, syntax, indent, comments)
+
+---
+
+## Installation
+
+### MELPA (when published)
+
+```elisp
+(use-package lumos-mode
+  :ensure t
+  :hook (lumos-mode . lsp-deferred))
+```
+
+### Manual
+
+```elisp
+(add-to-list 'load-path "~/.emacs.d/lisp/lumos-mode")
+(require 'lumos-mode)
+(add-hook 'lumos-mode-hook #'lsp-deferred)
+```
+
+---
+
+## Testing
+
+```bash
+# Run all tests
+make test
+
+# Byte compile
+make compile
+
+# Clean compiled files
+make clean
+```
+
+**Test Coverage**: 14 tests
+- Mode loading and derivation
+- File association
+- Syntax highlighting (keywords, types, attributes, comments)
+- Indentation (structs, enums)
+- Comment functionality
+- Custom variables
+
+---
+
+## Development Workflow
+
+### Making Changes
+
+1. Edit `lumos-mode.el`
+2. Run tests: `make test`
+3. Check compilation: `make compile`
+4. Test in Emacs:
+   ```elisp
+   M-x load-file RET lumos-mode.el RET
+   M-x lumos-mode
+   ```
+
+### Adding Features
+
+1. Implement feature in `lumos-mode.el`
+2. Add tests to `lumos-mode-test.el`
+3. Update README.md with usage instructions
+4. Run full test suite
+5. Update CLAUDE.md if architecture changes
+
+### CI Pipeline
+
+GitHub Actions runs on every push/PR:
+- Tests across Emacs 27.2, 28.2, 29.1, snapshot
+- package-lint validation
+- Byte compilation check
+
+---
+
+## Publishing to MELPA
+
+### Submission Process
+
+1. Ensure all tests pass
+2. Update version in `lumos-mode.el` header
+3. Create PR to [melpa/melpa](https://github.com/melpa/melpa) with recipe:
+
+```elisp
+(lumos-mode
+ :repo "getlumos/lumos-mode"
+ :fetcher github
+ :files ("*.el"))
+```
+
+4. MELPA maintainers review and merge
+5. Package available within 24 hours
+
+### Pre-submission Checklist
+
+- [ ] All tests passing locally
+- [ ] CI passing on GitHub
+- [ ] README.md complete
+- [ ] Version bumped in header
+- [ ] package-lint clean
+- [ ] Byte compilation clean
+
+---
+
+## LSP Integration
+
+### lumos-lsp Server
+
+The mode integrates with `lumos-lsp` (from core repo) for IDE features:
+
+- **Auto-completion**: Type suggestions
+- **Diagnostics**: Inline error checking
+- **Hover**: Documentation on hover
+- **Go to definition**: Jump to type definitions
+- **Find references**: Find all usages
+- **Rename**: Rename symbols across files
+
+### Configuration
+
+```elisp
+(setq lumos-lsp-server-command '("lumos-lsp" "--log-level" "debug"))
+```
+
+Server must be installed separately:
+
+```bash
+cargo install lumos-lsp
+```
+
+---
+
+## Customization
+
+### Variables
+
+```elisp
+;; Indentation width (default: 2)
+(setq lumos-indent-offset 4)
+
+;; LSP server command (default: '("lumos-lsp"))
+(setq lumos-lsp-server-command '("lumos-lsp" "--log-level" "info"))
+```
+
+### Keybindings
+
+```elisp
+(define-key lumos-mode-map (kbd "C-c C-c") 'lsp-execute-code-action)
+(define-key lumos-mode-map (kbd "C-c C-r") 'lsp-rename)
+(define-key lumos-mode-map (kbd "C-c C-f") 'lsp-format-buffer)
+```
+
+---
+
+## Related Repositories
+
+- **lumos** (core): Compiler, CLI, LSP server
+- **vscode-lumos**: VS Code extension
+- **intellij-lumos**: IntelliJ IDEA / Rust Rover plugin
+- **nvim-lumos**: Neovim plugin with Tree-sitter
+- **tree-sitter-lumos**: Tree-sitter grammar
+- **awesome-lumos**: Examples and templates
+- **docs-lumos**: Official documentation site
+
+---
+
+## AI Assistant Guidelines
+
+### ✅ DO
+
+- Run `make test` after any code changes
+- Update tests when adding new features
+- Keep README.md synchronized with code
+- Reference file:line when discussing code
+- Check CI passes before committing
+
+### ❌ DON'T
+
+- Skip running tests to save time
+- Add features without tests
+- Change indentation logic without extensive testing
+- Break backward compatibility with Emacs 26.1
+- Include AI attribution in commits or code
+
+---
+
+**Last Updated**: 2025-11-24
+**Version**: 0.1.0
+**Status**: Development