project_panel: Add diagnostic count badges (#49802)

Discussed in #6668 specifically this comment from @zackangelo:

> The biggest thing keeping me from using Zed as a daily driver is error
indication in the project panel. When I'm making big project-wide
changes I can't clearly see which files have errors (in editors like
VSCode the filenames turn red).

> VSCode seems to use a letter on the right gutter to indicate git
status and a number next to it to indicate diagnostic status. The color
indicates either.

This PR implements that, I added an opt-in `diagnostic_badges` setting
(default is false) that shows error and warning counts as colored labels
on the right side of each project panel entry. Counts bubble up to
parent directories.

When `diagnostic_badges` is enabled, diagnostic severity takes priority
over git status for entry text color.
Since warnings and git-modified share the same yellow, git status with
this option on is readable through the file icon decoration and the
absence of a number badge on the right.

Example:
<img width="522" height="785" alt="image"
src="https://github.com/user-attachments/assets/2da62580-86fe-480b-9b57-ff137ea42285"
/>


<img width="884" height="580" alt="image"
src="https://github.com/user-attachments/assets/198e9a45-dacd-4f1e-a66c-f2b84fd4db63"
/>

Release Notes:
- Added diagnostic count badges to the project panel, displaying error
and warning counts next to file names. You can modify this setting using
the `diagnostic_badges` option, which is enabled by default.

---------

Co-authored-by: Smit Barmase <heysmitbarmase@gmail.com>

assets/settings/default.json

@@ -799,6 +799,8 @@
     // 3. Show files first, then directories:
     //    "files_first"
     "sort_mode": "directories_first",
+    // Whether to show error and warning count badges next to file names in the project panel.
+    "diagnostic_badges": true,
     // Whether to enable drag-and-drop operations in the project panel.
     "drag_and_drop": true,
     // Whether to hide the root entry when only one folder is open in the window;

crates/project_panel/src/project_panel.rs

@@ -146,6 +146,7 @@ pub struct ProjectPanel {
     width: Option<Pixels>,
     pending_serialization: Task<Option<()>>,
     diagnostics: HashMap<(WorktreeId, Arc<RelPath>), DiagnosticSeverity>,
+    diagnostic_counts: HashMap<(WorktreeId, Arc<RelPath>), DiagnosticCount>,
     diagnostic_summary_update: Task<()>,
     // We keep track of the mouse down state on entries so we don't flash the UI
     // in case a user clicks to open a file.
@@ -232,6 +233,30 @@ enum ClipboardEntry {
     Cut(BTreeSet<SelectedEntry>),
 }
 
+#[derive(Debug, Default, PartialEq, Eq, Clone, Copy)]
+struct DiagnosticCount {
+    error_count: usize,
+    warning_count: usize,
+}
+
+impl DiagnosticCount {
+    fn capped_error_count(&self) -> String {
+        Self::capped_count(self.error_count)
+    }
+
+    fn capped_warning_count(&self) -> String {
+        Self::capped_count(self.warning_count)
+    }
+
+    fn capped_count(count: usize) -> String {
+        if count > 99 {
+            "99+".to_string()
+        } else {
+            count.to_string()
+        }
+    }
+}
+
 #[derive(Debug, PartialEq, Eq, Clone)]
 struct EntryDetails {
     filename: String,
@@ -249,6 +274,7 @@ struct EntryDetails {
     sticky: Option<StickyDetails>,
     filename_text_color: Color,
     diagnostic_severity: Option<DiagnosticSeverity>,
+    diagnostic_count: Option<DiagnosticCount>,
     git_status: GitSummary,
     is_private: bool,
     worktree_id: WorktreeId,
@@ -847,6 +873,7 @@ impl ProjectPanel {
                 width: None,
                 pending_serialization: Task::ready(None),
                 diagnostics: Default::default(),
+                diagnostic_counts: Default::default(),
                 diagnostic_summary_update: Task::ready(()),
                 scroll_handle,
                 mouse_down: false,
@@ -1029,6 +1056,26 @@ impl ProjectPanel {
                 });
         }
         self.diagnostics = diagnostics;
+
+        let diagnostic_badges = ProjectPanelSettings::get_global(cx).diagnostic_badges;
+        self.diagnostic_counts =
+            if diagnostic_badges && show_diagnostics_setting != ShowDiagnostics::Off {
+                self.project.read(cx).diagnostic_summaries(false, cx).fold(
+                    HashMap::default(),
+                    |mut counts, (project_path, _, summary)| {
+                        let entry = counts
+                            .entry((project_path.worktree_id, project_path.path))
+                            .or_default();
+                        entry.error_count += summary.error_count;
+                        if show_diagnostics_setting == ShowDiagnostics::All {
+                            entry.warning_count += summary.warning_count;
+                        }
+                        counts
+                    },
+                )
+            } else {
+                Default::default()
+            };
     }
 
     fn update_strongest_diagnostic_severity(
@@ -5044,6 +5091,7 @@ impl ProjectPanel {
 
         let filename_text_color = details.filename_text_color;
         let diagnostic_severity = details.diagnostic_severity;
+        let diagnostic_count = details.diagnostic_count;
         let item_colors = get_item_color(is_sticky, cx);
 
         let canonical_path = details
@@ -5482,22 +5530,55 @@ impl ProjectPanel {
                         ProjectPanelEntrySpacing::Standard => ListItemSpacing::ExtraDense,
                     })
                     .selectable(false)
-                    .when_some(canonical_path, |this, path| {
-                        this.end_slot::<AnyElement>(
-                            div()
-                                .id("symlink_icon")
-                                .pr_3()
-                                .tooltip(move |_window, cx| {
-                                    Tooltip::with_meta(path.to_string(), None, "Symbolic Link", cx)
-                                })
-                                .child(
-                                    Icon::new(IconName::ArrowUpRight)
-                                        .size(IconSize::Indicator)
-                                        .color(filename_text_color),
-                                )
-                                .into_any_element(),
-                        )
-                    })
+                    .when(
+                        canonical_path.is_some() || diagnostic_count.is_some(),
+                        |this| {
+                            let symlink_element = canonical_path.map(|path| {
+                                div()
+                                    .id("symlink_icon")
+                                    .tooltip(move |_window, cx| {
+                                        Tooltip::with_meta(
+                                            path.to_string(),
+                                            None,
+                                            "Symbolic Link",
+                                            cx,
+                                        )
+                                    })
+                                    .child(
+                                        Icon::new(IconName::ArrowUpRight)
+                                            .size(IconSize::Indicator)
+                                            .color(filename_text_color),
+                                    )
+                            });
+                            this.end_slot::<AnyElement>(
+                                h_flex()
+                                    .gap_1()
+                                    .flex_none()
+                                    .pr_3()
+                                    .when_some(diagnostic_count, |this, count| {
+                                        this.when(count.error_count > 0, |this| {
+                                            this.child(
+                                                Label::new(count.capped_error_count())
+                                                    .size(LabelSize::Small)
+                                                    .color(Color::Error),
+                                            )
+                                        })
+                                        .when(
+                                            count.warning_count > 0,
+                                            |this| {
+                                                this.child(
+                                                    Label::new(count.capped_warning_count())
+                                                        .size(LabelSize::Small)
+                                                        .color(Color::Warning),
+                                                )
+                                            },
+                                        )
+                                    })
+                                    .when_some(symlink_element, |this, el| this.child(el))
+                                    .into_any_element(),
+                            )
+                        },
+                    )
                     .child(if let Some(icon) = &icon {
                         if let Some((_, decoration_color)) =
                             entry_diagnostic_aware_icon_decoration_and_color(diagnostic_severity)
@@ -5907,6 +5988,11 @@ impl ProjectPanel {
             .get(&(worktree_id, entry.path.clone()))
             .cloned();
 
+        let diagnostic_count = self
+            .diagnostic_counts
+            .get(&(worktree_id, entry.path.clone()))
+            .copied();
+
         let filename_text_color =
             entry_git_aware_label_color(git_status, entry.is_ignored, is_marked);
 
@@ -5931,6 +6017,7 @@ impl ProjectPanel {
             sticky,
             filename_text_color,
             diagnostic_severity,
+            diagnostic_count,
             git_status,
             is_private: entry.is_private,
             worktree_id,

crates/project_panel/src/project_panel_settings.rs

@@ -35,6 +35,7 @@ pub struct ProjectPanelSettings {
     pub drag_and_drop: bool,
     pub auto_open: AutoOpenSettings,
     pub sort_mode: ProjectPanelSortMode,
+    pub diagnostic_badges: bool,
 }
 
 #[derive(Copy, Clone, Debug, Serialize, Deserialize, JsonSchema, PartialEq, Eq)]
@@ -125,9 +126,8 @@ impl Settings for ProjectPanelSettings {
                     on_drop: auto_open.on_drop.unwrap(),
                 }
             },
-            sort_mode: project_panel
-                .sort_mode
-                .unwrap_or(ProjectPanelSortMode::DirectoriesFirst),
+            sort_mode: project_panel.sort_mode.unwrap(),
+            diagnostic_badges: project_panel.diagnostic_badges.unwrap(),
         }
     }
 }

crates/settings/src/vscode_import.rs

@@ -801,6 +801,7 @@ impl VsCodeSettings {
             starts_open: None,
             sticky_scroll: None,
             auto_open: None,
+            diagnostic_badges: None,
         };
 
         if let (Some(false), Some(false)) = (

crates/settings_content/src/workspace.rs

@@ -739,6 +739,10 @@ pub struct ProjectPanelSettingsContent {
     ///
     /// Default: directories_first
     pub sort_mode: Option<ProjectPanelSortMode>,
+    /// Whether to show error and warning count badges next to file names in the project panel.
+    ///
+    /// Default: true
+    pub diagnostic_badges: Option<bool>,
 }
 
 #[derive(

crates/settings_ui/src/page_data.rs

@@ -4256,7 +4256,7 @@ fn window_and_layout_page() -> SettingsPage {
 }
 
 fn panels_page() -> SettingsPage {
-    fn project_panel_section() -> [SettingsPageItem; 21] {
+    fn project_panel_section() -> [SettingsPageItem; 22] {
         [
             SettingsPageItem::SectionHeader("Project Panel"),
             SettingsPageItem::SettingItem(SettingItem {
@@ -4556,6 +4556,28 @@ fn panels_page() -> SettingsPage {
                 metadata: None,
                 files: USER,
             }),
+            SettingsPageItem::SettingItem(SettingItem {
+                title: "Diagnostic Badges",
+                description: "Show error and warning count badges next to file names in the project panel.",
+                field: Box::new(SettingField {
+                    json_path: Some("project_panel.diagnostic_badges"),
+                    pick: |settings_content| {
+                        settings_content
+                            .project_panel
+                            .as_ref()?
+                            .diagnostic_badges
+                            .as_ref()
+                    },
+                    write: |settings_content, value| {
+                        settings_content
+                            .project_panel
+                            .get_or_insert_default()
+                            .diagnostic_badges = value;
+                    },
+                }),
+                metadata: None,
+                files: USER,
+            }),
             SettingsPageItem::SettingItem(SettingItem {
                 title: "Sticky Scroll",
                 description: "Whether to stick parent directories at top of the project panel.",