fix(snapshots): Handle odiff error responses without server restart

Application-level odiff errors (e.g., corrupt images) are valid protocol
responses — the server remains healthy. Separate them from transport
errors to avoid unnecessary process restarts.

Also fix layout reason string to match odiff server protocol
("layout-diff" not "layout").

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: NicoHinderling

src/commands/snapshots/diff.rs

@@ -206,39 +206,49 @@ pub fn execute(matches: &ArgMatches) -> Result<()> {
             }
 
             match server.compare(&base_file, &head_file, &mask_path) {
+                Ok(response) if response.error.is_some() => {
+                    errored_count += 1;
+                    images.push(ImageResult {
+                        name,
+                        status: "error".to_owned(),
+                        diff_percentage: None,
+                        diff_pixel_count: None,
+                        diff_mask_path: None,
+                        error: response.error,
+                    });
+                }
+                Ok(response) if response.is_match => {
+                    let _ = fs::remove_file(&mask_path);
+                    unchanged_count += 1;
+                    images.push(ImageResult {
+                        name,
+                        status: "unchanged".to_owned(),
+                        diff_percentage: response.diff_percentage,
+                        diff_pixel_count: response.diff_count,
+                        diff_mask_path: None,
+                        error: None,
+                    });
+                }
                 Ok(response) => {
-                    if response.is_match {
+                    let status = match response.reason.as_deref() {
+                        Some("layout-diff") => "layout_changed",
+                        _ => "changed",
+                    };
+                    changed_count += 1;
+                    let mask = if status == "layout_changed" {
                         let _ = fs::remove_file(&mask_path);
-                        unchanged_count += 1;
-                        images.push(ImageResult {
-                            name,
-                            status: "unchanged".to_owned(),
-                            diff_percentage: response.diff_percentage,
-                            diff_pixel_count: response.diff_count,
-                            diff_mask_path: None,
-                            error: None,
-                        });
+                        None
                     } else {
-                        let status = match response.reason.as_deref() {
-                            Some("layout") => "layout_changed",
-                            _ => "changed",
-                        };
-                        changed_count += 1;
-                        let mask = if status == "layout_changed" {
-                            let _ = fs::remove_file(&mask_path);
-                            None
-                        } else {
-                            Some(path_as_url(&mask_path))
-                        };
-                        images.push(ImageResult {
-                            name,
-                            status: status.to_owned(),
-                            diff_percentage: response.diff_percentage,
-                            diff_pixel_count: response.diff_count,
-                            diff_mask_path: mask,
-                            error: None,
-                        });
-                    }
+                        Some(path_as_url(&mask_path))
+                    };
+                    images.push(ImageResult {
+                        name,
+                        status: status.to_owned(),
+                        diff_percentage: response.diff_percentage,
+                        diff_pixel_count: response.diff_count,
+                        diff_mask_path: mask,
+                        error: None,
+                    });
                 }
                 Err(err) => {
                     errored_count += 1;

src/utils/odiff/server.rs

@@ -158,10 +158,6 @@ impl OdiffServer {
             );
         }
 
-        if let Some(ref err) = response.error {
-            bail!("odiff error comparing {}: {err}", base.display());
-        }
-
         Ok(response)
     }
 }
@@ -224,11 +220,11 @@ mod tests {
 
     #[test]
     fn test_response_deserialization_layout() {
-        let json = r#"{"requestId":3,"match":false,"reason":"layout"}"#;
+        let json = r#"{"requestId":3,"match":false,"reason":"layout-diff"}"#;
         let response: OdiffResponse =
             serde_json::from_str(json).expect("deserialization should succeed");
         assert!(!response.is_match);
-        assert_eq!(response.reason.as_deref(), Some("layout"));
+        assert_eq!(response.reason.as_deref(), Some("layout-diff"));
         assert!(response.diff_count.is_none());
     }