2 files changed, 63 insertions, 4 deletions
diff --git a/internal/processor/processor.go b/internal/processor/processor.go
index 43f5023..d781a8b 100644
--- a/internal/processor/processor.go
+++ b/internal/processor/processor.go
@@ -103,7 +103,10 @@ func claimedByMarkdown(entries []os.DirEntry, inputDir string) (map[string]bool,
 // The source file is removed from the input dir on success.
 func processFile(srcPath, postsDir string) error {
 	now := time.Now().UTC()
-	id := uniqueID(postsDir, now)
+	id, err := uniqueID(postsDir, now)
+	if err != nil {
+		return fmt.Errorf("generate unique ID: %w", err)
+	}
 
 	postDir := filepath.Join(postsDir, id)
 	if err := os.MkdirAll(postDir, 0o755); err != nil {
@@ -260,11 +263,15 @@ func copyLocalImages(filenames []string, sourceDir, postDir string) ([]string, e
 
 // uniqueID generates a post ID for the given time that does not already exist
 // as a directory under postsDir. Appends a numeric suffix if needed.
-func uniqueID(postsDir string, t time.Time) string {
+func uniqueID(postsDir string, t time.Time) (string, error) {
 	for i := 0; ; i++ {
 		id := post.NewID(t, i)
-		if _, err := os.Stat(filepath.Join(postsDir, id)); os.IsNotExist(err) {
-			return id
+		_, err := os.Stat(filepath.Join(postsDir, id))
+		if err != nil {
+			if os.IsNotExist(err) {
+				return id, nil
+			}
+			return "", fmt.Errorf("stat post dir %s: %w", id, err)
 		}
 	}
 }
diff --git a/internal/processor/processor_test.go b/internal/processor/processor_test.go
index d04a0d5..3b34675 100644
--- a/internal/processor/processor_test.go
+++ b/internal/processor/processor_test.go
@@ -6,6 +6,7 @@ import (
 	"os"
 	"path/filepath"
 	"testing"
+	"time"
 
 	"codeberg.org/snonux/snonux/internal/config"
 	"codeberg.org/snonux/snonux/internal/post"
@@ -141,6 +142,57 @@ func TestRun_markdown(t *testing.T) {
 	}
 }
 
+func TestUniqueID_new(t *testing.T) {
+	t.Parallel()
+
+	postsDir := t.TempDir()
+	id, err := uniqueID(postsDir, time.Now().UTC())
+	if err != nil {
+		t.Fatalf("uniqueID: %v", err)
+	}
+	if id == "" {
+		t.Fatal("expected non-empty id")
+	}
+}
+
+func TestUniqueID_collision(t *testing.T) {
+	t.Parallel()
+
+	postsDir := t.TempDir()
+	now := time.Now().UTC()
+
+	// Pre-create the first expected directory so uniqueID must pick the next suffix.
+	firstID := post.NewID(now, 0)
+	if err := os.MkdirAll(filepath.Join(postsDir, firstID), 0o755); err != nil {
+		t.Fatal(err)
+	}
+
+	id, err := uniqueID(postsDir, now)
+	if err != nil {
+		t.Fatalf("uniqueID: %v", err)
+	}
+	if id == firstID {
+		t.Fatalf("expected different id, got %q", id)
+	}
+}
+
+func TestUniqueID_statError(t *testing.T) {
+	t.Parallel()
+
+	// Create a postsDir and remove read permission so Stat fails with
+	// a permission error rather than IsNotExist.
+	postsDir := t.TempDir()
+	if err := os.Chmod(postsDir, 0o000); err != nil {
+		t.Fatal(err)
+	}
+	defer os.Chmod(postsDir, 0o755) // restore for cleanup
+
+	_, err := uniqueID(postsDir, time.Now().UTC())
+	if err == nil {
+		t.Fatal("expected error when stat fails")
+	}
+}
+
 func TestRun_markdownWithLocalImage(t *testing.T) {
 	t.Parallel()