dispatch: suggest --repos only where the flag is accepted

cmd/entire/cli/dispatch/mode_cloud.go

@@ -75,7 +75,7 @@ func runServer(ctx context.Context, opts Options) (*Dispatch, error) {
 		// repo on the other forge cannot answer for this checkout.
 		repoSlug, err := resolveOriginRepoSlug(ctx, repo)
 		if err != nil {
-			return nil, err
+			return nil, fmt.Errorf("%w (or pass --repos %s to name the repo)", err, RepoSlugShapes)
 		}
 		repos = []string{repoSlug}
 	}

cmd/entire/cli/dispatch/mode_local.go

@@ -475,20 +475,23 @@ func runGitOutput(ctx context.Context, repoRoot string, args ...string) (string,
 // forge-qualified slug (gh/<owner>/<repo> or et/<project>/<repo>), read from
 // the origin remote. The forge is whatever the remote points at, never
 // assumed, so an Entire-native checkout is addressed as the native repo.
+//
+// Errors name no flag: local mode refuses --repos, so the hint to pass it
+// belongs to the cloud caller alone.
 func resolveOriginRepoSlug(ctx context.Context, repo *git.Repository) (string, error) {
 	remote, err := repo.Remote("origin")
 	if err != nil {
 		logging.Warn(ctx, "dispatch repo resolution failed", "step", "origin_remote", "error", err)
-		return "", fmt.Errorf("dispatch needs an origin remote on GitHub or Entire (or pass --repos %s): %w", RepoSlugShapes, err)
+		return "", fmt.Errorf("dispatch needs an origin remote on GitHub or Entire: %w", err)
 	}
 	if len(remote.Config().URLs) == 0 {
-		return "", fmt.Errorf("dispatch needs an origin remote URL on GitHub or Entire (or pass --repos %s)", RepoSlugShapes)
+		return "", errors.New("dispatch needs an origin remote URL on GitHub or Entire")
 	}
 
 	slug, err := OriginRepoSlug(remote.Config().URLs[0])
 	if err != nil {
 		logging.Warn(ctx, "dispatch repo resolution failed", "step", "parse_origin_remote", "error", err)
-		return "", fmt.Errorf("dispatch cannot address this checkout's origin (pass --repos to name the repo): %w", err)
+		return "", fmt.Errorf("dispatch cannot address this checkout's origin: %w", err)
 	}
 	return slug, nil
 }

cmd/entire/cli/dispatch/mode_local_test.go

@@ -1363,3 +1363,29 @@ func addOriginRemoteURL(t *testing.T, repoDir, remoteURL string) {
 		t.Fatal(err)
 	}
 }
+
+// TestLocalMode_UnknownOriginHostDoesNotSuggestRepos: local mode refuses
+// --repos, so an origin it cannot address must not point the user at it.
+func TestLocalMode_UnknownOriginHostDoesNotSuggestRepos(t *testing.T) {
+	dir := t.TempDir()
+	testutil.InitRepo(t, dir)
+	testutil.WriteFile(t, dir, "a.txt", "x")
+	testutil.GitAdd(t, dir, "a.txt")
+	testutil.GitCommit(t, dir, "initial")
+	addOriginRemoteURL(t, dir, "https://gitlab.com/acme/thing.git")
+
+	t.Chdir(dir)
+
+	_, err := Run(context.Background(), Options{
+		Mode:          ModeLocal,
+		Since:         "7d",
+		Branches:      []string{"main"},
+		TextGenerator: stubGeneratedLocalDispatch(),
+	})
+	if err == nil || !strings.Contains(err.Error(), "gitlab.com") {
+		t.Fatalf("expected an error naming the host, got %v", err)
+	}
+	if strings.Contains(err.Error(), "--repos") {
+		t.Fatalf("local mode refuses --repos, so its error must not suggest it, got %v", err)
+	}
+}