feat(cli): exit 2 on restore cache miss

README.md

@@ -203,7 +203,7 @@ cachew namespaces
 
 # Directory snapshots
 cachew save <namespace> <directory> [paths...] (--key <key> | -H <glob>) [--ttl 1h] [--exclude pattern]
-cachew restore <namespace> <directory> (--key <key> | -H <glob>)
+cachew restore <namespace> <directory> (--key <key> | -H <glob>)  # exit 0 hit, 2 miss, 1 error
 
 # Git
 cachew git restore <repo-url> <directory> [--no-bundle]

cmd/cachew/main.go

@@ -38,7 +38,9 @@ type CLI struct {
 	Git GitCmd `cmd:"" help:"Git-aware operations." group:"Git:"`
 }
 
-func main() {
+func main() { os.Exit(run()) }
+
+func run() int {
 	cli := CLI{}
 	kctx := kong.Parse(&cli, kong.UsageOnError(), kong.HelpOptions{Compact: true}, kong.DefaultEnvars("CACHEW"), kong.Bind(&cli))
 	ctx := context.Background()
@@ -56,9 +58,19 @@ func main() {
 	kctx.BindTo(ctx, (*context.Context)(nil))
 	kctx.Bind(c)
 	kctx.Bind(c.HTTP())
-	kctx.FatalIfErrorf(kctx.Run(ctx))
+	err := kctx.Run(ctx)
+	if errors.Is(err, errCacheMiss) {
+		return 2
+	}
+	kctx.FatalIfErrorf(err)
+	return 0
 }
 
+// errCacheMiss signals that a restore found no object for the requested key.
+// Sentinel so main can exit with code 2 (distinct from generic errors at
+// code 1), matching conventions used by grep/diff.
+var errCacheMiss = errors.New("cache miss")
+
 type GetCmd struct {
 	Namespace client.Namespace `arg:"" help:"Namespace for organizing cache objects."`
 	Key       PlatformKey      `arg:"" help:"Object key (hex or string)."`
@@ -222,7 +234,8 @@ func (c *RestoreCmd) Run(ctx context.Context, api *client.Client, cli *CLI) erro
 		return errors.Wrap(err, "failed to restore")
 	}
 	if !hit {
-		return errors.Errorf("cache miss: %s", display)
+		fmt.Fprintf(os.Stderr, "Cache miss: %s\n", display) //nolint:forbidigo
+		return errCacheMiss
 	}
 
 	fmt.Fprintf(os.Stderr, "Restored: %s\n", display) //nolint:forbidigo

cmd/cachew/save_test.go

@@ -1,13 +1,17 @@
 package main
 
 import (
+	"context"
+	"net/http"
+	"net/http/httptest"
 	"os"
 	"path/filepath"
 	"runtime"
 	"testing"
 	"time"
 
 	"github.com/alecthomas/assert/v2"
+	"github.com/alecthomas/errors"
 
 	"github.com/block/cachew/client"
 )
@@ -53,3 +57,21 @@ func TestResolveKeyHashFilesNoMatch(t *testing.T) {
 	_, _, err := resolveKey(&CLI{}, "", []string{filepath.Join(t.TempDir(), "missing-*")})
 	assert.Error(t, err)
 }
+
+func TestRestoreCacheMiss(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		http.NotFound(w, nil) //nolint:staticcheck
+	}))
+	defer srv.Close()
+
+	api := client.New(srv.URL, nil)
+	defer api.Close()
+
+	cmd := &RestoreCmd{
+		Namespace: "test",
+		Directory: t.TempDir(),
+		Key:       "absent",
+	}
+	err := cmd.Run(context.Background(), api, &CLI{})
+	assert.True(t, errors.Is(err, errCacheMiss), "expected errCacheMiss sentinel, got %v", err)
+}