Add multi-runtime MCP config support (v0.6.0)

.gitignore

@@ -31,8 +31,10 @@ go.work.sum
 # .idea/
 # .vscode/
 
-# Generated MCP config
+# Generated MCP config (multi-runtime)
 .mcp.json
+.codex/config.toml
+.gemini/settings.json
 
 # Build output (agentfile CLI + agent binaries)
 build/

Makefile

@@ -43,5 +43,5 @@ bench-report:
 bench-all: bench bench-integration bench-report
 
 clean:
-	rm -rf build/ .agentfile/ .mcp.json
+	rm -rf build/ .agentfile/ .mcp.json .codex/config.toml .gemini/settings.json
 	go clean ./...

README.md

@@ -40,7 +40,7 @@ agentfile publish
 agentfile install github.com/acme/my-agent
 ```
 
-That last command downloads the right binary for your platform, wires it into Claude Code via MCP, and tracks it for future updates. No cloning, no building from source, no editing config files.
+That last command downloads the right binary for your platform, wires it into your MCP-compatible runtime (Claude Code, Codex, Gemini CLI — auto-detected), and tracks it for future updates. No cloning, no building from source, no editing config files.
 
 **Claude Code is the brain. The binary is the body** — it provides the instructions, the hands (tools), and the memory. Claude Code loads the agent's prompt, discovers its tools via MCP, and handles all reasoning.
 
@@ -90,9 +90,9 @@ You are a helpful coding assistant. Use your tools to read and modify files.
 
 ```bash
 agentfile build
-# -> ./build/my-agent binary + .mcp.json for Claude Code
+# -> ./build/my-agent binary + MCP config for detected runtimes
 
-# Claude Code auto-discovers the agent — start using it immediately
+# Your runtime auto-discovers the agent — start using it immediately
 ```
 
 ### 3. Share it

cmd/agentfile/build.go

@@ -9,6 +9,7 @@ import (
 	"github.com/teabranch/agentfile/pkg/builder"
 	"github.com/teabranch/agentfile/pkg/definition"
 	"github.com/teabranch/agentfile/pkg/plugin"
+	"github.com/teabranch/agentfile/pkg/runtimecfg"
 )
 
 // loadSkillFiles reads skill file contents from disk, resolving paths
@@ -42,6 +43,7 @@ func newBuildCommand() *cobra.Command {
 		agentName     string
 		pluginFlag    bool
 		parallelism   int
+		runtimeFlag   string
 	)
 
 	cmd := &cobra.Command{
@@ -50,9 +52,10 @@ func newBuildCommand() *cobra.Command {
 		Long: `Parses the Agentfile, reads each agent's .md file, generates Go source,
 and compiles standalone binaries into the output directory.
 
-Also generates/updates .mcp.json with serve-mcp entries for each agent.`,
+Also generates/updates MCP config for detected runtimes (Claude Code, Codex, Gemini).
+Use --runtime to target a specific runtime or "all" for all supported runtimes.`,
 		RunE: func(cmd *cobra.Command, args []string) error {
-			return runBuild(agentfilePath, outputDir, agentName, pluginFlag, parallelism)
+			return runBuild(agentfilePath, outputDir, agentName, pluginFlag, parallelism, runtimeFlag)
 		},
 	}
 
@@ -61,11 +64,12 @@ Also generates/updates .mcp.json with serve-mcp entries for each agent.`,
 	cmd.Flags().StringVar(&agentName, "agent", "", "Build a single agent by name")
 	cmd.Flags().BoolVar(&pluginFlag, "plugin", false, "Also generate a Claude Code plugin directory")
 	cmd.Flags().IntVar(&parallelism, "parallelism", 0, "Max concurrent agent builds (0 = sequential)")
+	cmd.Flags().StringVar(&runtimeFlag, "runtime", "auto", "Target runtime: auto, all, claude-code, codex, gemini")
 
 	return cmd
 }
 
-func runBuild(agentfilePath, outputDir, agentName string, pluginOutput bool, parallelism int) error {
+func runBuild(agentfilePath, outputDir, agentName string, pluginOutput bool, parallelism int, runtimeFlag string) error {
 	if agentfilePath == "" {
 		agentfilePath = resolveAgentfile()
 	}
@@ -121,20 +125,27 @@ func runBuild(agentfilePath, outputDir, agentName string, pluginOutput bool, par
 		return err
 	}
 
-	// Generate .mcp.json with serve-mcp entries.
+	// Generate MCP config for target runtimes.
+	writers, err := runtimecfg.Resolve(runtimeFlag)
+	if err != nil {
+		return fmt.Errorf("resolving runtimes: %w", err)
+	}
+
 	absOut, _ := filepath.Abs(outputDir)
-	entries := make(map[string]MCPServerEntry)
+	entries := make(map[string]runtimecfg.ServerEntry)
 	for name := range defs {
-		entries[name] = MCPServerEntry{
+		entries[name] = runtimecfg.ServerEntry{
 			Command: filepath.Join(absOut, name),
 			Args:    []string{"serve-mcp"},
 		}
 	}
 
-	if err := mergeMCPJSON(".mcp.json", entries); err != nil {
-		return fmt.Errorf("updating .mcp.json: %w", err)
+	for _, w := range writers {
+		if err := w.Merge(w.LocalPath(), entries); err != nil {
+			return fmt.Errorf("updating %s for %s: %w", w.LocalPath(), w.Runtime(), err)
+		}
+		fmt.Printf("Updated %s (%s)\n", w.LocalPath(), w.Runtime())
 	}
-	fmt.Println("Updated .mcp.json")
 
 	// Generate plugin directories if --plugin flag is set.
 	if pluginOutput {

cmd/agentfile/install.go

@@ -12,16 +12,18 @@ import (
 	"github.com/teabranch/agentfile/pkg/fsutil"
 	"github.com/teabranch/agentfile/pkg/github"
 	"github.com/teabranch/agentfile/pkg/registry"
+	"github.com/teabranch/agentfile/pkg/runtimecfg"
 )
 
 func newInstallCommand() *cobra.Command {
 	var global bool
 	var modelOverride string
+	var runtimeFlag string
 
 	cmd := &cobra.Command{
 		Use:   "install <agent-name | github.com/owner/repo[/agent][@version]>",
 		Short: "Install an agent binary (local or remote)",
-		Long: `Installs an agent binary and updates the MCP config.
+		Long: `Installs an agent binary and updates the MCP config for detected runtimes.
 
 Local install (from ./build/):
   agentfile install my-agent
@@ -30,26 +32,32 @@ Remote install (from GitHub Releases):
   agentfile install github.com/owner/repo/agent
   agentfile install github.com/owner/repo/agent@1.0.0
 
-By default, installs to .agentfile/bin/ (project-local) and updates .mcp.json.
-With --global, installs to /usr/local/bin/ and updates ~/.claude/mcp.json.
+By default, installs to .agentfile/bin/ (project-local) and updates MCP config.
+With --global, installs to /usr/local/bin/ and updates global MCP config.
 
 Override settings at install time:
-  agentfile install --model gpt-5 github.com/owner/repo/agent`,
+  agentfile install --model gpt-5 github.com/owner/repo/agent
+  agentfile install --runtime codex github.com/owner/repo/agent`,
 		Args: cobra.ExactArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {
+			writers, err := runtimecfg.Resolve(runtimeFlag)
+			if err != nil {
+				return err
+			}
+
 			var agentName string
 			if github.IsRemoteRef(args[0]) {
 				parsed, err := github.ParseRef(args[0])
 				if err != nil {
 					return err
 				}
 				agentName = parsed.Agent
-				if err := runRemoteInstall(args[0], global); err != nil {
+				if err := runRemoteInstall(args[0], global, writers); err != nil {
 					return err
 				}
 			} else {
 				agentName = args[0]
-				if err := runLocalInstall(args[0], global); err != nil {
+				if err := runLocalInstall(args[0], global, writers); err != nil {
 					return err
 				}
 			}
@@ -67,17 +75,18 @@ Override settings at install time:
 
 	cmd.Flags().BoolVarP(&global, "global", "g", false, "Install globally to /usr/local/bin")
 	cmd.Flags().StringVar(&modelOverride, "model", "", "Override the agent's model in ~/.agentfile/<name>/config.yaml")
+	cmd.Flags().StringVar(&runtimeFlag, "runtime", "auto", "Target runtime: auto, all, claude-code, codex, gemini")
 
 	return cmd
 }
 
-func runLocalInstall(name string, global bool) error {
+func runLocalInstall(name string, global bool, writers []runtimecfg.ConfigWriter) error {
 	src := filepath.Join("build", name)
 	if _, err := os.Stat(src); err != nil {
 		return fmt.Errorf("binary not found: %s (run 'agentfile build' first)", src)
 	}
 
-	binDir, mcpPath := installPaths(global)
+	binDir := installBinDir(global)
 
 	if err := os.MkdirAll(binDir, 0o755); err != nil {
 		return fmt.Errorf("creating bin dir: %w", err)
@@ -92,21 +101,20 @@ func runLocalInstall(name string, global bool) error {
 	}
 	fmt.Printf("Installed %s → %s\n", name, dst)
 
-	// Update mcp.json.
+	// Update MCP configs for target runtimes.
 	absDst, err := filepath.Abs(dst)
 	if err != nil {
 		return fmt.Errorf("resolving absolute path: %w", err)
 	}
-	entries := map[string]MCPServerEntry{
+	entries := map[string]runtimecfg.ServerEntry{
 		name: {
 			Command: absDst,
 			Args:    []string{"serve-mcp"},
 		},
 	}
-	if err := mergeMCPJSON(mcpPath, entries); err != nil {
-		return fmt.Errorf("updating %s: %w", mcpPath, err)
+	if err := mergeRuntimeConfigs(writers, global, entries); err != nil {
+		return err
 	}
-	fmt.Printf("Updated %s\n", mcpPath)
 
 	// Track in registry.
 	version := ""
@@ -120,7 +128,7 @@ func runLocalInstall(name string, global bool) error {
 	return trackInstall(name, "local", version, absDst, scope)
 }
 
-func runRemoteInstall(ref string, global bool) error {
+func runRemoteInstall(ref string, global bool, writers []runtimecfg.ConfigWriter) error {
 	parsed, err := github.ParseRef(ref)
 	if err != nil {
 		return err
@@ -196,7 +204,7 @@ func runRemoteInstall(ref string, global bool) error {
 	}
 
 	// Move to install location.
-	binDir, mcpPath := installPaths(global)
+	binDir := installBinDir(global)
 	if err := os.MkdirAll(binDir, 0o755); err != nil {
 		return fmt.Errorf("creating bin dir: %w", err)
 	}
@@ -210,21 +218,20 @@ func runRemoteInstall(ref string, global bool) error {
 	}
 	fmt.Printf("Installed %s → %s\n", parsed.Agent, dst)
 
-	// Wire MCP.
+	// Wire MCP for target runtimes.
 	absDst, err := filepath.Abs(dst)
 	if err != nil {
 		return fmt.Errorf("resolving absolute path: %w", err)
 	}
-	entries := map[string]MCPServerEntry{
+	entries := map[string]runtimecfg.ServerEntry{
 		parsed.Agent: {
 			Command: absDst,
 			Args:    []string{"serve-mcp"},
 		},
 	}
-	if err := mergeMCPJSON(mcpPath, entries); err != nil {
-		return fmt.Errorf("updating %s: %w", mcpPath, err)
+	if err := mergeRuntimeConfigs(writers, global, entries); err != nil {
+		return err
 	}
-	fmt.Printf("Updated %s\n", mcpPath)
 
 	// Track in registry.
 	source := fmt.Sprintf("github.com/%s/%s/%s", parsed.Owner, parsed.Repo, parsed.Agent)
@@ -235,16 +242,34 @@ func runRemoteInstall(ref string, global bool) error {
 	return trackInstall(parsed.Agent, source, manifest.Version, absDst, scope)
 }
 
-func installPaths(global bool) (binDir, mcpPath string) {
+// installBinDir returns the binary install directory.
+// Binary location is agentfile-internal, independent of runtime.
+func installBinDir(global bool) string {
 	if global {
-		binDir = "/usr/local/bin"
-		home, _ := os.UserHomeDir()
-		mcpPath = filepath.Join(home, ".claude", "mcp.json")
-	} else {
-		binDir = filepath.Join(".agentfile", "bin")
-		mcpPath = ".mcp.json"
+		return "/usr/local/bin"
+	}
+	return filepath.Join(".agentfile", "bin")
+}
+
+// mergeRuntimeConfigs writes MCP server entries to all target runtime configs.
+func mergeRuntimeConfigs(writers []runtimecfg.ConfigWriter, global bool, entries map[string]runtimecfg.ServerEntry) error {
+	for _, w := range writers {
+		var cfgPath string
+		if global {
+			var err error
+			cfgPath, err = w.GlobalPath()
+			if err != nil {
+				return fmt.Errorf("resolving global path for %s: %w", w.Runtime(), err)
+			}
+		} else {
+			cfgPath = w.LocalPath()
+		}
+		if err := w.Merge(cfgPath, entries); err != nil {
+			return fmt.Errorf("updating %s for %s: %w", cfgPath, w.Runtime(), err)
+		}
+		fmt.Printf("Updated %s (%s)\n", cfgPath, w.Runtime())
 	}
-	return
+	return nil
 }
 
 func trackInstall(name, source, version, path, scope string) error {

cmd/agentfile/main.go

@@ -9,7 +9,7 @@ import (
 	"github.com/spf13/cobra"
 )
 
-const cliVersion = "0.5.0"
+const cliVersion = "0.6.0"
 
 func main() {
 	root := newRootCommand()