diff --git a/cmd/review-bot/main.go b/cmd/review-bot/main.go
index e967981..788408e 100644
--- a/cmd/review-bot/main.go
+++ b/cmd/review-bot/main.go
@@ -429,7 +429,7 @@ func main() {
 		currentSHA = currentPR.Head.SHA
 	}
 	if shouldSkipStaleReview(evaluatedSHA, currentSHA) {
-		slog.Warn("HEAD moved during review — skipping stale review",
+		slog.Warn("HEAD moved during review -- skipping stale review",
 			"evaluated", evaluatedSHA,
 			"current", currentSHA,
 			"pr", prNumber)
@@ -477,12 +477,12 @@ func main() {
 	}
 
 	// Self-request as reviewer (Gitea-specific; ensures we appear in required-reviewer checks)
-	if giteaAdapter, ok := client.(*gitea.Adapter); ok {
+	if selfReq, ok := client.(vcs.ReviewerSelfRequester); ok {
 		authUser, err := client.GetAuthenticatedUser(ctx)
 		if err != nil {
 			slog.Warn("could not determine authenticated user for reviewer self-request", "error", err)
 		} else if authUser != "" {
-			if err := giteaAdapter.Underlying().RequestReviewer(ctx, owner, repoName, prNumber, authUser); err != nil {
+			if err := selfReq.RequestReviewerSelf(ctx, owner, repoName, prNumber, authUser); err != nil {
 				slog.Warn("could not self-request as reviewer", "user", authUser, "error", err)
 			} else {
 				slog.Debug("self-requested as reviewer", "user", authUser, "pr", prNumber)
@@ -563,6 +563,10 @@ func supersedeOldReviews(ctx context.Context, client vcs.Client, provider, vcsUR
 	}
 	underlying := giteaAdapter.Underlying()
 
+	// Validate vcsURL scheme before embedding in Markdown link (defense-in-depth).
+	if !strings.HasPrefix(vcsURL, "http://") && !strings.HasPrefix(vcsURL, "https://") {
+		return fmt.Errorf("supersedeOldReviews: vcsURL must have http or https scheme, got %q", vcsURL)
+	}
 	newReviewURL := fmt.Sprintf("%s/%s/%s/pulls/%d#pullrequestreview-%d", strings.TrimRight(vcsURL, "/"), owner, repoName, prNumber, newReviewID)
 	for _, oldReview := range oldReviews {
 		cid, err := underlying.GetTimelineReviewCommentIDForReview(ctx, owner, repoName, prNumber, oldReview.ID)
@@ -757,14 +761,6 @@ func envOrDefaultInt(key string, defaultVal int) int {
 	return defaultVal
 }
 
-func envOrDefaultBool(key string, defaultVal bool) bool {
-	v := strings.TrimSpace(strings.ToLower(os.Getenv(key)))
-	if v == "" {
-		return defaultVal
-	}
-	return v == "true" || v == "1" || v == "yes"
-}
-
 // validateReviewerName checks that the name contains only safe characters
 // for embedding in an HTML comment sentinel ([a-zA-Z0-9_-]).
 func validateReviewerName(name string) error {
@@ -858,7 +854,7 @@ func hasSharedToken(reviews []vcs.Review, ownSentinel string) bool {
 	}
 	for _, r := range reviews {
 		if r.User.Login == ownLogin && strings.Contains(r.Body, "<!-- review-bot:") && !strings.Contains(r.Body, ownSentinel) {
-			slog.Warn("shared token detected — another review-bot role is using the same VCS user",
+			slog.Warn("shared token detected -- another review-bot role is using the same VCS user",
 				"sibling_role", extractSentinelName(r.Body), "user", ownLogin)
 			return true
 		}
diff --git a/cmd/review-bot/main_test.go b/cmd/review-bot/main_test.go
index f492b16..3f88d8f 100644
--- a/cmd/review-bot/main_test.go
+++ b/cmd/review-bot/main_test.go
@@ -596,47 +596,6 @@ func TestEnvOrDefaultInt(t *testing.T) {
 	}
 }
 
-func TestEnvOrDefaultBool(t *testing.T) {
-	tests := []struct {
-		name       string
-		envVal     string
-		setEnv     bool
-		defaultVal bool
-		want       bool
-	}{
-		{"unset returns default true", "", false, true, true},
-		{"unset returns default false", "", false, false, false},
-		{"true", "true", true, false, true},
-		{"TRUE", "TRUE", true, false, true},
-		{"True", "True", true, false, true},
-		{"1", "1", true, false, true},
-		{"yes", "yes", true, false, true},
-		{"YES", "YES", true, false, true},
-		{"false", "false", true, true, false},
-		{"0", "0", true, true, false},
-		{"no", "no", true, true, false},
-		{"random string", "random", true, true, false},
-		{"empty string returns default", "", true, true, true},
-		{"whitespace true", "  true  ", true, false, true},
-	}
-
-	for _, tc := range tests {
-		t.Run(tc.name, func(t *testing.T) {
-			envKey := "TEST_ENV_BOOL_" + strings.ReplaceAll(tc.name, " ", "_")
-			if tc.setEnv {
-				os.Setenv(envKey, tc.envVal)
-				defer os.Unsetenv(envKey)
-			} else {
-				os.Unsetenv(envKey)
-			}
-			got := envOrDefaultBool(envKey, tc.defaultVal)
-			if got != tc.want {
-				t.Errorf("envOrDefaultBool(%q, %v) = %v, want %v", tc.envVal, tc.defaultVal, got, tc.want)
-			}
-		})
-	}
-}
-
 func TestExtractSentinelName_EdgeCases(t *testing.T) {
 	tests := []struct {
 		body string
diff --git a/gitea/adapter.go b/gitea/adapter.go
index 4cef61e..905c36c 100644
--- a/gitea/adapter.go
+++ b/gitea/adapter.go
@@ -16,6 +16,7 @@ type Adapter struct {
 
 // Compile-time interface conformance assertion.
 var _ vcs.Client = (*Adapter)(nil)
+var _ vcs.ReviewerSelfRequester = (*Adapter)(nil)
 
 // NewAdapter creates a new Adapter wrapping the given gitea Client.
 func NewAdapter(client *Client) *Adapter {
@@ -230,3 +231,9 @@ func (a *Adapter) DismissReview(ctx context.Context, owner, repo string, number
 func (a *Adapter) GetAuthenticatedUser(ctx context.Context) (string, error) {
 	return a.client.GetAuthenticatedUser(ctx)
 }
+
+// RequestReviewerSelf adds the given user as a requested reviewer on a pull request.
+// This implements vcs.ReviewerSelfRequester for the Gitea adapter.
+func (a *Adapter) RequestReviewerSelf(ctx context.Context, owner, repo string, number int, user string) error {
+	return a.client.RequestReviewer(ctx, owner, repo, number, user)
+}
diff --git a/gitea/adapter_test.go b/gitea/adapter_test.go
index 0071699..a4aea9d 100644
--- a/gitea/adapter_test.go
+++ b/gitea/adapter_test.go
@@ -386,3 +386,25 @@ func TestAdapter_GetFileContent_RefRouting(t *testing.T) {
 		t.Errorf("GetFileContent(ref=\"abc123\") = %q, want %q", got, "content-at-ref")
 	}
 }
+
+func TestAdapter_RequestReviewerSelf(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodPost {
+			t.Errorf("expected POST, got %s", r.Method)
+		}
+		expected := "/api/v1/repos/owner/repo/pulls/5/requested_reviewers"
+		if r.URL.Path != expected {
+			t.Errorf("path = %q, want %q", r.URL.Path, expected)
+		}
+		w.WriteHeader(http.StatusCreated)
+	}))
+	defer server.Close()
+
+	client := gitea.NewClient(server.URL, "token")
+	adapter := gitea.NewAdapter(client)
+
+	err := adapter.RequestReviewerSelf(context.Background(), "owner", "repo", 5, "bot-user")
+	if err != nil {
+		t.Fatalf("RequestReviewerSelf() error = %v", err)
+	}
+}
diff --git a/vcs/interfaces.go b/vcs/interfaces.go
index 3bc299e..61f3483 100644
--- a/vcs/interfaces.go
+++ b/vcs/interfaces.go
@@ -41,3 +41,11 @@ type Client interface {
 	Reviewer
 	Identity
 }
+
+// ReviewerSelfRequester is an optional interface implemented by adapters that support
+// requesting the authenticated user as a reviewer on a pull request. This is used for
+// Gitea-specific behavior (ensuring the bot appears in required-reviewer checks).
+// Consumers should use interface assertion: if sr, ok := client.(ReviewerSelfRequester); ok { ... }
+type ReviewerSelfRequester interface {
+	RequestReviewerSelf(ctx context.Context, owner, repo string, number int, user string) error
+}