aitools: add skills command for coding agents (#4125)

## Changes

Add `databricks experimental aitools skills` subcommand to install Agent
Skills for coding agents:
- `skills list` - list available skills from the databricks-agent-skills
repo
- `skills install [skill-name]` - install skills to detected coding
agents

### Multi-agent support

Automatically detects and installs skills for:
- Claude Code (`~/.claude/skills/`)
- Cursor (`~/.cursor/skills/`)
- Codex CLI (`~/.codex/skills/`)
- OpenCode (`~/.config/opencode/skills/`)
- GitHub Copilot (`~/.copilot/skills/`)
- Antigravity (`~/.gemini/antigravity/global_skills/`)

When multiple agents are detected, skills are installed to a canonical
location (`~/.databricks/agent-skills/`) and symlinked to each agent to
avoid duplication.

### Refactored agent registry

Unified agent detection logic in `lib/agents/agents.go` - shared between
skills installation and MCP installation commands.

## Why

Skills are simpler than MCP for providing domain-specific guidance to AI
agents. While MCP requires a running server, skills are static
documentation that agents load on demand. This gives users a lightweight
way to get Databricks-specific guidance across all major coding agents.

## Tests

Manual testing:
```bash
databricks experimental aitools skills list
databricks experimental aitools skills install
databricks experimental aitools skills install databricks-apps
```

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: arsenyinfo

experimental/aitools/cmd/aitools.go

@@ -28,6 +28,7 @@ Provides commands to:
 
 	cmd.AddCommand(newMcpCmd())
 	cmd.AddCommand(newInstallCmd())
+	cmd.AddCommand(newSkillsCmd())
 	cmd.AddCommand(newToolsCmd())
 
 	return cmd

experimental/aitools/cmd/install.go

@@ -30,25 +30,24 @@ func runInstall(ctx context.Context) error {
 	// Check for non-interactive mode with agent detection
 	// If running in an AI agent, install automatically without prompts
 	if !cmdio.IsPromptSupported(ctx) {
+		var targetAgent *agents.Agent
 		switch agent.Product(ctx) {
 		case agent.ClaudeCode:
-			if err := agents.InstallClaude(); err != nil {
-				return err
-			}
-			cmdio.LogString(ctx, color.GreenString("✓ Installed Databricks MCP server for Claude Code"))
-			cmdio.LogString(ctx, color.YellowString("⚠️  Please restart Claude Code for changes to take effect"))
-			return nil
+			targetAgent = agents.GetByName("claude-code")
 		case agent.Cursor:
-			if err := agents.InstallCursor(); err != nil {
+			targetAgent = agents.GetByName("cursor")
+		}
+
+		if targetAgent != nil && targetAgent.InstallMCP != nil {
+			if err := targetAgent.InstallMCP(); err != nil {
 				return err
 			}
-			cmdio.LogString(ctx, color.GreenString("✓ Installed Databricks MCP server for Cursor"))
-			cmdio.LogString(ctx, color.YellowString("⚠️  Please restart Cursor for changes to take effect"))
+			cmdio.LogString(ctx, color.GreenString("✓ Installed Databricks MCP server for %s", targetAgent.DisplayName))
+			cmdio.LogString(ctx, color.YellowString("⚠️  Please restart %s for changes to take effect", targetAgent.DisplayName))
 			return nil
-		default:
-			// Unknown agent in non-interactive mode - show manual instructions
-			return agents.ShowCustomInstructions(ctx)
 		}
+		// Unknown agent in non-interactive mode - show manual instructions
+		return agents.ShowCustomInstructions(ctx)
 	}
 
 	cmdio.LogString(ctx, "")
@@ -69,39 +68,32 @@ func runInstall(ctx context.Context) error {
 
 	anySuccess := false
 
-	ans, err := cmdio.AskSelect(ctx, "Install for Claude Code?", []string{"yes", "no"})
-	if err != nil {
-		return err
-	}
-	if ans == "yes" {
-		fmt.Fprint(os.Stderr, "Installing MCP server for Claude Code...")
-		if err := agents.InstallClaude(); err != nil {
-			fmt.Fprint(os.Stderr, "\r"+color.YellowString("⊘ Skipped Claude Code: "+err.Error())+"\n")
-		} else {
-			fmt.Fprint(os.Stderr, "\r"+color.GreenString("✓ Installed for Claude Code")+"                 \n")
-			anySuccess = true
+	// Install for agents that have MCP support
+	for i := range agents.Registry {
+		a := &agents.Registry[i]
+		if a.InstallMCP == nil {
+			continue
 		}
-		cmdio.LogString(ctx, "")
-	}
 
-	ans, err = cmdio.AskSelect(ctx, "Install for Cursor?", []string{"yes", "no"})
-	if err != nil {
-		return err
-	}
-	if ans == "yes" {
-		fmt.Fprint(os.Stderr, "Installing MCP server for Cursor...")
-		if err := agents.InstallCursor(); err != nil {
-			fmt.Fprint(os.Stderr, "\r"+color.YellowString("⊘ Skipped Cursor: "+err.Error())+"\n")
-		} else {
-			// Brief delay so users see the "Installing..." message before it's replaced
-			time.Sleep(1 * time.Second)
-			fmt.Fprint(os.Stderr, "\r"+color.GreenString("✓ Installed for Cursor")+"                 \n")
-			anySuccess = true
+		ans, err := cmdio.AskSelect(ctx, fmt.Sprintf("Install for %s?", a.DisplayName), []string{"yes", "no"})
+		if err != nil {
+			return err
+		}
+		if ans == "yes" {
+			fmt.Fprintf(os.Stderr, "Installing MCP server for %s...", a.DisplayName)
+			if err := a.InstallMCP(); err != nil {
+				fmt.Fprint(os.Stderr, "\r"+color.YellowString("⊘ Skipped %s: %s", a.DisplayName, err.Error())+"\n")
+			} else {
+				// Brief delay so users see the "Installing..." message before it's replaced
+				time.Sleep(500 * time.Millisecond)
+				fmt.Fprint(os.Stderr, "\r"+color.GreenString("✓ Installed for %s", a.DisplayName)+"                 \n")
+				anySuccess = true
+			}
+			cmdio.LogString(ctx, "")
 		}
-		cmdio.LogString(ctx, "")
 	}
 
-	ans, err = cmdio.AskSelect(ctx, "Show manual installation instructions for other agents?", []string{"yes", "no"})
+	ans, err := cmdio.AskSelect(ctx, "Show manual installation instructions for other agents?", []string{"yes", "no"})
 	if err != nil {
 		return err
 	}