Add support for Apple Foundation Models (fm) provider

README.md

@@ -14,8 +14,9 @@ blank commit message.
 
 - **Pluggable providers**: GitHub Copilot, OpenAI-compatible Chat
   Completions APIs (including local servers like Ollama and LM Studio), or
-  the local [`apfel`](https://github.com/Arthur-Ficial/apfel) on-device
-  model (macOS only) — no network calls required. A provider must be
+  the local [`apfel`](https://github.com/Arthur-Ficial/apfel) or built-in
+  `fm` Apple Foundation Models CLI (macOS only) — no network calls required.
+  A provider must be
   selected explicitly via `--provider`/a shortcut flag, `LAZYCOMMIT_PROVIDER`,
   or `git config lazycommit.provider`; there is no default.
 - **Editor review by default**: the generated message is pre-populated in
@@ -84,13 +85,14 @@ lazycommit.provider copilot"); precedence is flag > env var > git config.
 
 Options:
   -p, --patch          Interactively stage hunks via git add -p before committing
-      --provider <p>    Provider to use: copilot, openai, apfel (or use LAZYCOMMIT_PROVIDER)
+      --provider <p>    Provider to use: copilot, openai, apfel, fm (or use LAZYCOMMIT_PROVIDER)
       --model <m>       Model name to use (provider-specific default if omitted; or use LAZYCOMMIT_MODEL)
       --base-url <url>  Override the API base URL (copilot/openai providers)
       --api-key <key>   API key/OAuth token to use (openai/copilot providers; or use OPENAI_API_KEY)
       --prompt <text>   Override the prompt template (or use LAZYCOMMIT_PROMPT)
       --copilot         Shorthand for --provider copilot
       --apfel           Shorthand for --provider apfel (local Apple model, no network; macOS only)
+      --fm              Shorthand for --provider fm (local Apple Foundation Model, macOS 27+ only)
       --ollama          Shorthand for --provider openai --base-url http://localhost:11434/v1
       --lmstudio        Shorthand for --provider openai --base-url http://localhost:1234/v1
       --no-edit         Skip the $EDITOR review step and commit the message as-is
@@ -128,7 +130,7 @@ Prompt template:
 
 A provider must be specified — either pass `--provider <name>`/a shortcut
 flag on every invocation, set `export LAZYCOMMIT_PROVIDER=copilot` (or
-`openai`/`apfel`) once, or run `git config lazycommit.provider copilot` so
+`openai`/`apfel`/`fm`) once, or run `git config lazycommit.provider copilot` so
 you don't have to repeat it:
 
 ```sh
@@ -150,6 +152,9 @@ lazycommit --provider openai --model gpt-4o --api-key sk-...
 # Use the local apfel model (no network calls, macOS only)
 lazycommit --provider apfel   # or: lazycommit --apfel
 
+# Use the built-in Apple Foundation Models CLI (macOS 27+ only)
+lazycommit --provider fm --model system   # or: lazycommit --fm
+
 # Use a local Ollama or LM Studio server (OpenAI-compatible, no API key needed)
 lazycommit --ollama
 lazycommit --lmstudio
@@ -218,18 +223,35 @@ instead of trying (and failing) to exec a nonexistent `apfel` binary.
   — it just talks to whatever on-device model `apfel` provides); using
   `--list-models --apfel`/`--list-models --provider apfel` is an error.
 
+### `fm` (macOS 27+ only)
+
+Shells out to the built-in Apple Foundation Models CLI (`fm`) with
+`fm respond --no-stream` to run the local on-device model — no network calls
+or API key. Equivalent to `--provider fm` or the `--fm` shorthand.
+
+Available beginning with macOS 27, `fm` and its underlying on-device model
+are Apple-only. `lazycommit` binaries built for other platforms omit the
+real provider implementation entirely (via a Go build constraint), so
+selecting `fm`/`--fm` on Linux or Windows fails immediately with a clear
+error.
+
+- `--model` selects the `fm` model when supplied; `fm` currently provides
+  the `system` model.
+- Does not support `--list-models`; using
+  `--list-models --fm`/`--list-models --provider fm` is an error.
+
 ## Configuration
 
 Settings can be provided via a CLI flag, an environment variable, or a
 `git config` key, in that order of precedence (flags win over environment
 variables, which win over `git config`). `--provider` (or one of
-`--copilot`/`--apfel`/`--ollama`/`--lmstudio`), `LAZYCOMMIT_PROVIDER`, or
+`--copilot`/`--apfel`/`--fm`/`--ollama`/`--lmstudio`), `LAZYCOMMIT_PROVIDER`, or
 `git config lazycommit.provider` is **required** — there is no default
 provider.
 
 | Flag          | Environment variable   | `git config` key         | Description                                        |
 |---------------|-------------------------|---------------------------|------------------------------------------------------|
-| `--provider`  | `LAZYCOMMIT_PROVIDER`  | `lazycommit.provider`     | Provider to use: `copilot`, `openai`, or `apfel` (macOS only) (required) |
+| `--provider`  | `LAZYCOMMIT_PROVIDER`  | `lazycommit.provider`     | Provider to use: `copilot`, `openai`, `apfel`, or `fm` (macOS only) (required) |
 | `--model`     | `LAZYCOMMIT_MODEL`     | `lazycommit.model`        | Model name (provider-specific default if omitted)   |
 | `--prompt`    | `LAZYCOMMIT_PROMPT`    | `lazycommit.prompt`       | Prompt template override (see below)                |
 | `--base-url`  | `GITHUB_API_URL`       | `lazycommit.baseUrl`      | Base URL override for the `copilot` provider         |

internal/app/args.go

@@ -79,6 +79,9 @@ func ParseArgs(args []string) (*Config, []string, error) {
 		case "--apfel":
 			// Shorthand for --provider apfel.
 			cfg.Provider = "apfel"
+		case "--fm":
+			// Shorthand for --provider fm.
+			cfg.Provider = "fm"
 		case "--copilot":
 			// Shorthand for --provider copilot.
 			cfg.Provider = "copilot"
@@ -142,13 +145,14 @@ lazycommit.provider copilot"); precedence is flag > env var > git config.
 
 Options:
   -p, --patch          Interactively stage hunks via git add -p before committing
-      --provider <p>    Provider to use: copilot, openai, apfel (or use LAZYCOMMIT_PROVIDER)
+      --provider <p>    Provider to use: copilot, openai, apfel, fm (or use LAZYCOMMIT_PROVIDER)
       --model <m>       Model name to use (provider-specific default if omitted; or use LAZYCOMMIT_MODEL)
       --base-url <url>  Override the API base URL (copilot/openai providers)
       --api-key <key>   API key/OAuth token to use (openai/copilot providers; or use OPENAI_API_KEY)
       --prompt <text>   Override the prompt template (or use LAZYCOMMIT_PROMPT)
       --copilot         Shorthand for --provider copilot
       --apfel           Shorthand for --provider apfel (local Apple model, no network; macOS only)
+      --fm              Shorthand for --provider fm (local Apple Foundation Model, macOS 27+ only)
       --ollama          Shorthand for --provider openai --base-url http://localhost:11434/v1
       --lmstudio        Shorthand for --provider openai --base-url http://localhost:1234/v1
       --no-edit         Skip the $EDITOR review step and commit the message as-is

internal/app/args_test.go

@@ -56,6 +56,11 @@ func TestParseArgs(t *testing.T) {
 			args:    []string{"--apfel"},
 			wantCfg: Config{Provider: "apfel"},
 		},
+		{
+			name:    "fm shorthand",
+			args:    []string{"--fm"},
+			wantCfg: Config{Provider: "fm"},
+		},
 		{
 			name:    "copilot shorthand",
 			args:    []string{"--copilot"},

internal/app/fm_darwin.go

@@ -0,0 +1,9 @@
+//go:build darwin
+
+package app
+
+import "github.com/evilmarty/lazycommit/provider"
+
+func newFMProvider(model string) (provider.Generator, error) {
+	return &provider.FoundationModelProvider{Model: model}, nil
+}

internal/app/fm_darwin_test.go

@@ -0,0 +1,37 @@
+//go:build darwin
+
+package app
+
+import (
+	"testing"
+
+	"github.com/evilmarty/lazycommit/provider"
+)
+
+func TestNewFMProviderDarwin(t *testing.T) {
+	gen, err := newFMProvider("system")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	fm, ok := gen.(*provider.FoundationModelProvider)
+	if !ok {
+		t.Fatalf("expected *provider.FoundationModelProvider, got %T", gen)
+	}
+	if fm.Model != "system" {
+		t.Errorf("expected Model system, got %q", fm.Model)
+	}
+}
+
+func TestNewProviderFMViaFactoryDarwin(t *testing.T) {
+	gen, err := NewProvider(ProviderConfig{Name: "fm", Model: "system"}, sources(nil, nil))
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	fm, ok := gen.(*provider.FoundationModelProvider)
+	if !ok {
+		t.Fatalf("expected *provider.FoundationModelProvider, got %T", gen)
+	}
+	if fm.Model != "system" {
+		t.Errorf("expected Model system, got %q", fm.Model)
+	}
+}

internal/app/fm_other.go

@@ -0,0 +1,13 @@
+//go:build !darwin
+
+package app
+
+import (
+	"fmt"
+
+	"github.com/evilmarty/lazycommit/provider"
+)
+
+func newFMProvider(_ string) (provider.Generator, error) {
+	return nil, fmt.Errorf("unknown provider %q: fm is only supported on macOS", "fm")
+}

internal/app/fm_other_test.go

@@ -0,0 +1,34 @@
+//go:build !darwin
+
+package app
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestNewFMProviderNonDarwin(t *testing.T) {
+	gen, err := newFMProvider("system")
+	if err == nil {
+		t.Fatal("expected error on non-darwin platforms")
+	}
+	if gen != nil {
+		t.Fatalf("expected nil Generator, got %v", gen)
+	}
+	if !strings.Contains(err.Error(), "macOS") {
+		t.Errorf("expected error to mention macOS, got %q", err)
+	}
+}
+
+func TestNewProviderFMViaFactoryNonDarwin(t *testing.T) {
+	gen, err := NewProvider(ProviderConfig{Name: "fm"}, sources(nil, nil))
+	if err == nil {
+		t.Fatal("expected error on non-darwin platforms")
+	}
+	if gen != nil {
+		t.Fatalf("expected nil Generator, got %v", gen)
+	}
+	if !strings.Contains(err.Error(), "macOS") {
+		t.Errorf("expected error to mention macOS, got %q", err)
+	}
+}

internal/app/provider_factory.go

@@ -172,8 +172,10 @@ func NewProvider(cfg ProviderConfig, sources Sources) (provider.Generator, error
 		}, nil
 	case "apfel":
 		return newApfelProvider()
+	case "fm":
+		return newFMProvider(cfg.Model)
 	default:
-		return nil, fmt.Errorf("unknown provider %q (expected copilot, openai, or apfel)", cfg.Name)
+		return nil, fmt.Errorf("unknown provider %q (expected copilot, openai, apfel, or fm)", cfg.Name)
 	}
 }
 

internal/app/run.go

@@ -80,7 +80,7 @@ func RunWithDeps(args []string, stdout, stderr io.Writer, getenv GetEnv, deps De
 	if cfg.ListModels {
 		providerName := ResolveProvider(cfg.Provider, sources)
 		if providerName == "" {
-			fmt.Fprintln(stderr, "\u274c  No provider specified. Use --provider <name>, a shortcut flag (--copilot, --apfel, --ollama, --lmstudio), or set LAZYCOMMIT_PROVIDER.")
+			fmt.Fprintln(stderr, "\u274c  No provider specified. Use --provider <name>, a shortcut flag (--copilot, --apfel, --fm, --ollama, --lmstudio), or set LAZYCOMMIT_PROVIDER.")
 			return 1
 		}
 		model := ResolveModel(cfg.Model, sources)
@@ -139,7 +139,7 @@ func RunWithDeps(args []string, stdout, stderr io.Writer, getenv GetEnv, deps De
 
 	providerName := ResolveProvider(cfg.Provider, sources)
 	if providerName == "" {
-		fmt.Fprintln(stderr, "\u274c  No provider specified. Use --provider <name>, a shortcut flag (--copilot, --apfel, --ollama, --lmstudio), or set LAZYCOMMIT_PROVIDER.")
+		fmt.Fprintln(stderr, "\u274c  No provider specified. Use --provider <name>, a shortcut flag (--copilot, --apfel, --fm, --ollama, --lmstudio), or set LAZYCOMMIT_PROVIDER.")
 		return 1
 	}
 	model := ResolveModel(cfg.Model, sources)

internal/app/run_test.go

@@ -164,19 +164,22 @@ func TestRunListModelsListError(t *testing.T) {
 }
 
 func TestRunListModelsUnsupportedProvider(t *testing.T) {
-	var stdout, stderr bytes.Buffer
-	deps := Deps{
-		NewProvider: func(cfg ProviderConfig, sources Sources) (provider.Generator, error) {
-			// apfel (and any provider that doesn't implement ModelLister).
-			return fakeGenerator{}, nil
-		},
-	}
-	code := RunWithDeps([]string{"--list-models", "--apfel"}, &stdout, &stderr, envMap(nil), deps)
-	if code != 1 {
-		t.Fatalf("expected exit 1, got %d", code)
-	}
-	if !strings.Contains(stderr.String(), "does not support listing models") {
-		t.Errorf("expected unsupported-provider error, got %q", stderr.String())
+	for _, providerFlag := range []string{"--apfel", "--fm"} {
+		t.Run(providerFlag, func(t *testing.T) {
+			var stdout, stderr bytes.Buffer
+			deps := Deps{
+				NewProvider: func(cfg ProviderConfig, sources Sources) (provider.Generator, error) {
+					return fakeGenerator{}, nil
+				},
+			}
+			code := RunWithDeps([]string{"--list-models", providerFlag}, &stdout, &stderr, envMap(nil), deps)
+			if code != 1 {
+				t.Fatalf("expected exit 1, got %d", code)
+			}
+			if !strings.Contains(stderr.String(), "does not support listing models") {
+				t.Errorf("expected unsupported-provider error, got %q", stderr.String())
+			}
+		})
 	}
 }
 

main.go

@@ -1,5 +1,5 @@
 // Command lazycommit auto-generates a commit message from the staged diff
-// using a pluggable LLM provider (Copilot, OpenAI, or the local apfel CLI),
+// using a pluggable LLM provider (Copilot, OpenAI, or a local macOS CLI),
 // optionally opens it in $EDITOR for review, then commits.
 package main
 

provider/fm.go

@@ -0,0 +1,43 @@
+//go:build darwin
+
+package provider
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/evilmarty/lazycommit/internal/cmdrunner"
+)
+
+// FoundationModelProvider generates commit messages using macOS's local
+// Apple Foundation Models CLI, avoiding any network calls.
+type FoundationModelProvider struct {
+	Model string
+	// Runner executes the fm command. Defaults to cmdrunner.Exec when nil;
+	// overridable in tests.
+	Runner cmdrunner.Runner
+}
+
+func (p *FoundationModelProvider) runner() cmdrunner.Runner {
+	if p.Runner != nil {
+		return p.Runner
+	}
+	return cmdrunner.Exec
+}
+
+// Generate implements Generator.
+func (p *FoundationModelProvider) Generate(_ context.Context, prompt string) (string, error) {
+	args := []string{"respond", "--no-stream"}
+	if p.Model != "" {
+		args = append(args, "--model", p.Model)
+	}
+	args = append(args, prompt)
+
+	out, err := p.runner()("fm", args)
+	if err != nil {
+		return "", fmt.Errorf("local generation with fm failed: %w", err)
+	}
+
+	return strings.TrimSpace(string(out)), nil
+}