diff --git a/cmd/review-bot/main.go b/cmd/review-bot/main.go
index 7a59ded..ca42dfb 100644
--- a/cmd/review-bot/main.go
+++ b/cmd/review-bot/main.go
@@ -170,7 +170,8 @@ func main() {
 		}
 		client = github.NewClient(*reviewerToken, ghBaseURL)
 	default:
-		panic("unreachable: unhandled provider " + *provider)
+		fmt.Fprintf(os.Stderr, "Error: unhandled provider %q\n", *provider)
+		os.Exit(1)
 	}
 	slog.Info("VCS client initialized", "provider", *provider)
 
@@ -523,7 +524,8 @@ func verdictToEvent(verdict string) vcs.ReviewEvent {
 // For GitHub: dismisses old reviews.
 // For Gitea: edits the review body and resolves inline comments.
 func supersedeOldReviews(ctx context.Context, client vcs.Client, provider, vcsURL, owner, repoName string, prNumber int, oldReviews []vcs.Review, newReviewID int64, sentinel string) error {
-	if provider == "github" {
+	switch provider {
+	case "github":
 		for _, old := range oldReviews {
 			if err := client.DismissReview(ctx, owner, repoName, prNumber, old.ID, "Superseded by new review"); err != nil {
 				slog.Warn("failed to dismiss review", "id", old.ID, "error", err)
@@ -532,9 +534,12 @@ func supersedeOldReviews(ctx context.Context, client vcs.Client, provider, vcsUR
 			}
 		}
 		return nil
+	case "gitea":
+		// Gitea: EditComment + ResolveComment flow
+	default:
+		return fmt.Errorf("supersedeOldReviews: unsupported provider %q", provider)
 	}
 
-	// Gitea: existing EditComment + ResolveComment flow
 	giteaAdapter, ok := client.(*gitea.Adapter)
 	if !ok {
 		return fmt.Errorf("expected gitea.Adapter for gitea provider, got %T", client)
diff --git a/github/reviews.go b/github/reviews.go
index c6ed536..1d8066f 100644
--- a/github/reviews.go
+++ b/github/reviews.go
@@ -42,7 +42,6 @@ type reviewCommentCreate struct {
 // dismissReviewRequest is the GitHub API request body for dismissing a review.
 type dismissReviewRequest struct {
 	Message string `json:"message"`
-	Event   string `json:"event"`
 }
 
 // userResponse is the GitHub API response for the authenticated user.
@@ -60,7 +59,7 @@ func translateReviewEvent(event vcs.ReviewEvent) string {
 	case vcs.ReviewEventComment:
 		return "COMMENT"
 	default:
-		return string(event)
+		return "COMMENT"
 	}
 }
 
@@ -161,7 +160,6 @@ func (c *Client) DismissReview(ctx context.Context, owner, repo string, number i
 
 	payload := dismissReviewRequest{
 		Message: message,
-		Event:   "DISMISS",
 	}
 
 	_, err := c.doJSONRequest(ctx, http.MethodPut, reqURL, payload)