diff --git a/src-tauri/src/agents/history.rs b/src-tauri/src/agents/history.rs
index 578667a..4b0306e 100644
--- a/src-tauri/src/agents/history.rs
+++ b/src-tauri/src/agents/history.rs
@@ -610,7 +610,9 @@ fn commit_history_with_writer(
     if image_revision(&history_images(paths)?) != image_revision(before) {
         return Err("配置已被其他程序修改，请刷新后重试".into());
     }
-    if changed.is_empty() {
+    let prior_mappings = matching_desktop_mappings(client, paths, before);
+    let next_mappings = mappings.or_else(|| matching_desktop_mappings(client, paths, after));
+    if changed.is_empty() && prior_mappings == next_mappings {
         return Ok(action_result(
             "unchanged",
             true,
@@ -620,9 +622,12 @@ fn commit_history_with_writer(
         ));
     }
     let mut prior = make_version(client, paths, before, &format!("before-{source}"), None);
-    prior.mappings = matching_desktop_mappings(client, paths, before);
+    prior.mappings = prior_mappings;
+    if let Some(mappings) = prior.mappings.as_ref() {
+        prior.model = Some(mappings.opus.clone());
+    }
     let mut next = make_version(client, paths, after, source, model.clone());
-    next.mappings = mappings.or_else(|| matching_desktop_mappings(client, paths, after));
+    next.mappings = next_mappings;
     write_version(paths, &prior)?;
     if image_revision(&history_images(paths)?) != image_revision(before) {
         return Err("备份期间配置发生变化，请刷新后重试".into());
@@ -823,9 +828,27 @@ fn preview(
             });
         }
     }
+    let current_mappings = matching_desktop_mappings(client, paths, &current);
+    if client == "claude-desktop" && current_mappings != version.mappings {
+        let before = serde_json::to_value(&current_mappings).map_err(|e| e.to_string())?;
+        let after = serde_json::to_value(&version.mappings).map_err(|e| e.to_string())?;
+        let mut fields = BTreeSet::new();
+        collect_changes(Some(&before), Some(&after), Vec::new(), &mut fields);
+        for field in fields {
+            differences.push(HistoryDifference {
+                file: path_to_string(&paths[2]),
+                field: format!("modelMappings.{}", field.join(".")),
+                before: hidden(get(&before, &field), &field),
+                after: hidden(get(&after, &field), &field),
+            });
+        }
+    }
+    let revision = sha256_bytes(
+        format!("{}:{}", image_revision(&current), serde_json::to_string(&current_mappings).map_err(|e| e.to_string())?).as_bytes(),
+    );
     Ok((
         HistoryPreview {
-            revision: image_revision(&current),
+            revision,
             differences,
         },
         current,
diff --git a/src-tauri/src/agents/history/tests.rs b/src-tauri/src/agents/history/tests.rs
index 3b065f4..776aa12 100644
--- a/src-tauri/src/agents/history/tests.rs
+++ b/src-tauri/src/agents/history/tests.rs
@@ -405,3 +405,44 @@ fn directory_at_config_path_is_an_error() {
     fs::create_dir_all(&paths[0]).unwrap();
     assert!(history_images(&paths).is_err());
 }
+
+fn desktop_test_models() -> Vec<AgentModelOption> {
+    ["model-a", "model-b"].into_iter().map(|name| AgentModelOption {
+        name: name.into(), alias: None, is_alias: false, context_window: Some(200_000),
+    }).collect()
+}
+
+fn apply_desktop_test_model(home: &Path, model: &str) -> AgentConfigActionResult {
+    let mappings = ClaudeDesktopModelMappings::all(model);
+    apply_agent_configuration_with_oauth(
+        AgentClient::ClaudeDesktop, home, 8317, "test-key", model,
+        AgentConfigurationOptions {
+            models: &desktop_test_models(), codex_catalog: None, oauth_configuration: false,
+            claude_code_model_mappings: None, claude_desktop_model_mappings: Some(&mappings),
+        },
+    ).unwrap()
+}
+
+#[test]
+fn desktop_mapping_changes_are_saved_when_profile_bytes_are_identical() {
+    let home = Home::new();
+    let paths = history_paths("claude-desktop", &home.0).unwrap();
+    let first = apply_desktop_test_model(&home.0, "model-a");
+    let images = history_images(&paths).unwrap();
+    let first_id = first.history_version.unwrap();
+    let original_preview = preview("claude-desktop", &paths, &first_id).unwrap().0;
+    let second = apply_desktop_test_model(&home.0, "model-b");
+    assert_eq!(second.outcome, "updated");
+    assert!(second.changed_files.is_empty());
+    assert!(second.history_version.is_some());
+    assert_eq!(images, history_images(&paths).unwrap());
+    assert_eq!(versions("claude-desktop", &paths).unwrap().0.len(), 4);
+    assert_eq!(current_desktop_history_mappings(&home.0).unwrap().opus, "model-b");
+    let next_preview = preview("claude-desktop", &paths, &first_id).unwrap().0;
+    assert_ne!(original_preview.revision, next_preview.revision);
+    assert!(next_preview.differences.iter().any(|diff| diff.field == "modelMappings.opus"));
+    let unchanged = apply_desktop_test_model(&home.0, "model-b");
+    assert_eq!(unchanged.outcome, "unchanged");
+    assert!(unchanged.history_version.is_none());
+    assert_eq!(versions("claude-desktop", &paths).unwrap().0.len(), 4);
+}