feat: add first-class GitHub Copilot support to mxcli init

Register 'copilot' in SupportedTools so 'mxcli init --tool copilot'
generates .github/copilot-instructions.md — Copilot's project-level
instructions file that VS Code automatically loads.

The generated file is compact (Copilot has a smaller instruction
context window than Claude Code) and includes:
- Critical ./mxcli (not mxcli) rule
- Quick command examples (SHOW STRUCTURE, check, exec, search)
- MDL syntax reminders (entities, microflow vars, page widgets)
- Pointers to AGENTS.md and .ai-context/skills/ for full reference

Also works with 'mxcli add-tool copilot' for existing projects.

Closes #183

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

Author: ako

cmd/mxcli/cmd_add_tool.go

@@ -37,6 +37,8 @@ Supported Tools:
   - windsurf    Windsurf (Codeium) with MDL rules
   - aider       Aider with project configuration
   - opencode    OpenCode AI agent with MDL commands and skills
+  - vibe        Mistral Vibe CLI agent with skills
+  - copilot     GitHub Copilot with project-level instructions
 `,
 	Args: cobra.RangeArgs(0, 2),
 	Run: func(cmd *cobra.Command, args []string) {

cmd/mxcli/init.go

@@ -88,6 +88,7 @@ Supported Tools:
   - aider       Aider with project configuration
   - opencode    OpenCode AI agent with MDL commands and skills
   - vibe        Mistral Vibe CLI agent with skills
+  - copilot     GitHub Copilot with project-level instructions
 
 All tools receive universal documentation in AGENTS.md and .ai-context/
 

cmd/mxcli/tool_templates.go

@@ -104,6 +104,16 @@ var SupportedTools = map[string]ToolConfig{
 		},
 		// Skills are synced dynamically from the embedded skillsFS in init.go
 	},
+	"copilot": {
+		Name:        "GitHub Copilot",
+		Description: "GitHub Copilot with project-level instructions",
+		Files: []ToolFile{
+			{
+				Path:    ".github/copilot-instructions.md",
+				Content: generateCopilotInstructions,
+			},
+		},
+	},
 }
 
 // Universal files created for all tools
@@ -447,6 +457,50 @@ allowed-tools:
 	return []byte(frontmatter + string(content))
 }
 
+// generateCopilotInstructions creates .github/copilot-instructions.md, the
+// project-level instructions file automatically loaded by GitHub Copilot in VS Code.
+// Kept compact since Copilot's instruction context window is smaller than Claude Code's.
+func generateCopilotInstructions(projectName, mprPath string) string {
+	mprFile := filepath.Base(mprPath)
+	return fmt.Sprintf("# Mendix MDL Project: %s\n\n"+
+		"This project uses **mxcli** to read and modify Mendix model files (`.mpr`) via MDL "+
+		"(Mendix Definition Language) — a SQL-like text format for Mendix applications.\n\n"+
+		"## Critical: mxcli Location\n\n"+
+		"The mxcli binary is in the **project root**, not on PATH:\n"+
+		"- ✅ `./mxcli ...`\n"+
+		"- ❌ `mxcli ...` (will fail)\n\n"+
+		"MPR file: `%s`\n\n"+
+		"## Quick Commands\n\n"+
+		"```bash\n"+
+		"# Explore project structure\n"+
+		"./mxcli -p %s -c \"SHOW STRUCTURE\"\n\n"+
+		"# Validate an MDL script (always do this before executing)\n"+
+		"./mxcli check script.mdl -p %s --references\n\n"+
+		"# Execute an MDL script\n"+
+		"./mxcli exec script.mdl -p %s\n\n"+
+		"# Search the project\n"+
+		"./mxcli search -p %s \"keyword\"\n"+
+		"```\n\n"+
+		"## Where to Look First\n\n"+
+		"- **`AGENTS.md`** — full mxcli reference, MDL command list, workflow examples.\n"+
+		"- **`.ai-context/skills/`** — focused syntax guides for microflows, pages, "+
+		"domain models, security, etc. **Read the relevant skill before writing MDL.**\n\n"+
+		"## MDL Syntax Reminders\n\n"+
+		"- **Entities:** `CREATE PERSISTENT ENTITY Mod.Customer (Name: String(200), Age: Integer);`\n"+
+		"- **Microflow variables:** start with `$` (e.g., `$Customer`, `$List`).\n"+
+		"- **Page widgets:** nest with `{ }`, properties use `(Key: value, ...)`.\n"+
+		"- **Single quotes in expressions:** escape by doubling — `'it''s here'`.\n"+
+		"- **No `AS` keyword** in entity attribute declarations.\n"+
+		"- **Statements** end with `;` or `/` on a line by itself.\n\n"+
+		"## Workflow\n\n"+
+		"1. Explore: read `AGENTS.md` and the relevant `.ai-context/skills/` file first.\n"+
+		"2. Write MDL in a `.mdl` file.\n"+
+		"3. Validate: `./mxcli check <file>.mdl -p %s --references`.\n"+
+		"4. Execute: `./mxcli exec <file>.mdl -p %s`.\n"+
+		"5. Verify: `./mxcli -p %s -c \"DESCRIBE ENTITY Mod.Name\"`.\n",
+		projectName, mprFile, mprFile, mprFile, mprFile, mprFile, mprFile, mprFile, mprFile)
+}
+
 func generateOpenCodeConfig(projectName, mprPath string) string {
 	return `{
   "$schema": "https://opencode.ai/config.json",

docs-site/src/ide/mxcli-init.md

@@ -52,6 +52,7 @@ mxcli init --list-tools
 | **Windsurf** | `--tool windsurf` | `.windsurfrules` |
 | **Aider** | `--tool aider` | `.aider.conf.yml` |
 | **Mistral Vibe** | `--tool vibe` | `.vibe/config.toml`, `.vibe/prompts/`, `.vibe/skills/` |
+| **GitHub Copilot** | `--tool copilot` | `.github/copilot-instructions.md` |
 
 All tools also receive the universal files (`AGENTS.md`, `.ai-context/`).
 

docs-site/src/tutorial/other-ai-tools.md

@@ -67,7 +67,7 @@ On top of the universal files, each tool gets its own configuration:
 |------|-------------|----------|
 | **Claude Code** | `.claude/`, `CLAUDE.md` | Settings, skills, commands, lint rules, project context |
 | **OpenCode** | `.opencode/`, `opencode.json` | Skills, commands, lint rules, project context |
-| **GitHub Copilot** | `AGENTS.md` | Reads universal context automatically via VS Code |
+| **GitHub Copilot** | `.github/copilot-instructions.md`, `AGENTS.md` | Project-level instructions auto-loaded by Copilot in VS Code |
 | **Cursor** | `.cursorrules` | Compact MDL reference and mxcli command guide |
 | **Continue.dev** | `.continue/config.json` | Custom commands and slash commands |
 | **Windsurf** | `.windsurfrules` | MDL rules for Codeium's AI |
@@ -86,16 +86,15 @@ mxcli init --tool opencode /path/to/project
 
 ### GitHub Copilot
 
-GitHub Copilot works with mxcli out of the box via the universal `AGENTS.md` file — no dedicated `--tool` flag is needed. Copilot's agent mode in VS Code automatically reads markdown files in the project root, so after running `mxcli init`, Copilot has access to the full MDL reference and skill files.
+GitHub Copilot has dedicated support via `--tool copilot`, which generates `.github/copilot-instructions.md` — Copilot's project-level instructions file that's automatically loaded in VS Code.
 
 ```bash
-# Any mxcli init creates AGENTS.md, which Copilot reads automatically
-mxcli init /path/to/project
+mxcli init --tool copilot /path/to/project
 ```
 
-For many organizations, Copilot is the default AI assistant as part of their Microsoft/GitHub enterprise agreement. mxcli supports this by ensuring the universal files (`AGENTS.md`, `.ai-context/skills/`) provide enough context for Copilot to work effectively with MDL.
+The generated file is compact (Copilot has a smaller instruction context window than Claude Code) and points to `AGENTS.md` and `.ai-context/skills/` for full reference material. It includes the critical `./mxcli` (not `mxcli`) rule, quick command examples, and MDL syntax reminders.
 
-To use: open the project in VS Code with the GitHub Copilot extension, open Copilot Chat (Ctrl+Shift+I), and ask for Mendix changes. Copilot will reference `AGENTS.md` and the skill files for MDL syntax guidance.
+For many organizations, Copilot is the default AI assistant as part of their Microsoft/GitHub enterprise agreement. To use: open the project in VS Code with the GitHub Copilot extension, open Copilot Chat (Ctrl+Shift+I), and ask for Mendix changes. Copilot will reference `.github/copilot-instructions.md`, `AGENTS.md`, and the skill files for MDL syntax guidance.
 
 ### Cursor