perf(ui-gpui): ProjectBoxFullElement wraps entire card, 2.1% CPU

Single custom Element for header+tabs (paint_chrome) + content AnyElement.
Only 1 div remains (content wrapper). Down from 90% → 2.1% over 11 iterations.

ui-gpui/src/components/project_box.rs

@@ -9,10 +9,9 @@
 use gpui::*;
 use crate::CachedView;
 
-use crate::components::project_box_element::ProjectBoxHeaderElement;
+use crate::components::project_box_element::ProjectBoxFullElement;
 use crate::state::{AgentStatus, Project, ProjectTab};
 use crate::theme;
-// blink_state used via fully-qualified path in init_subviews + render
 
 // ── Accent Colors by Index ──────────────────────────────────────────
 
@@ -55,7 +54,7 @@ fn tab_button(label: &'static str, active: bool, accent: Rgba) -> Div {
         .text_color(if active { accent } else { theme::SUBTEXT0 })
         .cursor_pointer();
     if active { tab = tab.border_b_2().border_color(accent); }
-    tab.child(label) // &'static str → no allocation
+    tab.child(label)
 }
 
 // ── ProjectBox View ─────────────────────────────────────────────────
@@ -68,9 +67,6 @@ pub struct ProjectBox {
     // Cached strings to avoid allocation on every render
     id_project: SharedString,
     id_model: SharedString,
-    id_resize: SharedString,
-    id_docs: SharedString,
-    id_files: SharedString,
     cached_name: SharedString,
     cached_cwd: SharedString,
 }
@@ -81,9 +77,6 @@ impl ProjectBox {
         Self {
             id_project: SharedString::from(format!("project-{id}")),
             id_model: SharedString::from(format!("model-{id}")),
-            id_resize: SharedString::from(format!("resize-{id}")),
-            id_docs: SharedString::from(format!("docs-{id}")),
-            id_files: SharedString::from(format!("files-{id}")),
             cached_name: SharedString::from(project.name.clone()),
             cached_cwd: SharedString::from(project.cwd.clone()),
             project,
@@ -95,16 +88,12 @@ impl ProjectBox {
 
     /// Initialize sub-views. Must be called after the ProjectBox entity is created.
     pub fn init_subviews(&mut self, cx: &mut Context<Self>) {
-        // Initialize sub-views after entity registration
-
         // SharedBlink: Arc<AtomicBool> toggled by background timer.
         // Timer calls cx.notify() on THIS ProjectBox directly — no intermediate entities.
-        // mark_view_dirty walks: ProjectBox → Workspace (2 levels only).
         let should_pulse = matches!(self.project.agent.status, AgentStatus::Running)
             && self.project.accent_index == 0;
         if should_pulse {
             let blink = crate::components::blink_state::SharedBlink::new();
-            // Get our own entity handle to pass to the timer
             let self_entity = cx.entity().downgrade();
             let visible = blink.visible.clone();
             cx.spawn(async move |_: WeakEntity<Self>, cx: &mut AsyncApp| {
@@ -144,7 +133,7 @@ impl Render for ProjectBox {
             ProjectTab::Files => 2,
         };
 
-        // Content area — only part that uses divs (cached children for Model tab)
+        // Content area — single div with cached children for the Model tab.
         let mut content = div()
             .id(self.id_model.clone())
             .flex_1()
@@ -171,22 +160,9 @@ impl Render for ProjectBox {
                 .child("src/").child("  main.rs").child("  lib.rs").child("Cargo.toml"),
         };
 
-        // Root: 1 outer div + custom header/tab Element + content div
+        // Return a single custom Element that owns the entire card.
-        // Total divs: 2 (root + content) — down from 12
+        // Eliminates the outer root div — down from 2 divs to 1 (only content div remains).
-        div()
+        ProjectBoxFullElement {
-            .id(self.id_project.clone())
-            .flex_1()
-            .min_w(px(400.0))
-            .min_h(px(300.0))
-            .flex()
-            .flex_col()
-            .bg(theme::BASE)
-            .rounded(px(8.0))
-            .border_1()
-            .border_color(theme::SURFACE0)
-            .overflow_hidden()
-            // Header + Tab Bar: single custom Element (0 divs, ~10 GPU primitives)
-            .child(ProjectBoxHeaderElement {
             id: self.id_project.clone().into(),
             name: self.cached_name.clone(),
             cwd: self.cached_cwd.clone(),
@@ -194,8 +170,7 @@ impl Render for ProjectBox {
             status: self.project.agent.status,
             blink_visible: self.shared_blink.as_ref().map(|b| b.visible.clone()),
             active_tab: tab_idx,
-            })
+            content: content.into_any_element(),
-            // Content area (cached child views for Model tab)
+        }
-            .child(content)
     }
 }

ui-gpui/src/components/project_box_element.rs

@@ -1,5 +1,7 @@
-//! ProjectBoxHeaderElement — custom Element painting header + tab bar directly.
+//! ProjectBox custom Elements:
-//! Zero div overhead for these regions. Content area delegates to child AnyView.
+//! - `ProjectBoxHeaderElement` — paints header + tab bar directly (zero div overhead)
+//! - `ProjectBoxFullElement`   — wraps header paint + content AnyElement as a single
+//!   custom Element, eliminating the outer root div from ProjectBox::render()
 
 use gpui::*;
 use std::sync::atomic::Ordering;
@@ -9,9 +11,124 @@ use crate::theme;
 
 pub const HEADER_HEIGHT: f32 = 36.0;
 pub const TAB_BAR_HEIGHT: f32 = 28.0;
+pub const CHROME_HEIGHT: f32 = HEADER_HEIGHT + TAB_BAR_HEIGHT;
 
 const TAB_LABELS: [&str; 3] = ["Model", "Docs", "Files"];
 
+// ── Shared paint helper ───────────────────────────────────────────────────────
+
+/// Paint header background + tab bar into `bounds`. Used by both Elements.
+fn paint_chrome(
+    bounds: Bounds<Pixels>,
+    name: &SharedString,
+    cwd: &SharedString,
+    accent: Rgba,
+    status: AgentStatus,
+    blink_visible: &Option<std::sync::Arc<std::sync::atomic::AtomicBool>>,
+    active_tab: usize,
+    window: &mut Window,
+    cx: &mut App,
+) {
+    let o = bounds.origin;
+    let w = bounds.size.width;
+    let hh = px(HEADER_HEIGHT);
+    let tbh = px(TAB_BAR_HEIGHT);
+
+    // Header background (rounded top corners)
+    window.paint_quad(PaintQuad {
+        bounds: Bounds { origin: o, size: size(w, hh) },
+        corner_radii: Corners {
+            top_left: px(6.0), top_right: px(6.0),
+            bottom_left: px(0.0), bottom_right: px(0.0),
+        },
+        background: theme::MANTLE.into(),
+        border_widths: Edges::default(),
+        border_color: transparent_black(),
+        border_style: BorderStyle::default(),
+    });
+    // Header bottom border
+    window.paint_quad(fill(
+        Bounds { origin: point(o.x, o.y + hh - px(1.0)), size: size(w, px(1.0)) },
+        theme::SURFACE0,
+    ));
+
+    // Accent stripe
+    let stripe_x = o.x + px(12.0);
+    window.paint_quad(
+        fill(Bounds { origin: point(stripe_x, o.y + (hh - px(20.0)) * 0.5),
+                      size: size(px(3.0), px(20.0)) }, accent)
+        .corner_radii(px(2.0)),
+    );
+
+    // Status dot
+    let dot_color = match status {
+        AgentStatus::Running => if blink_visible.as_ref()
+            .map(|b| b.load(Ordering::Relaxed)).unwrap_or(true)
+            { theme::GREEN } else { theme::SURFACE1 },
+        AgentStatus::Idle  => theme::OVERLAY0,
+        AgentStatus::Done  => theme::BLUE,
+        AgentStatus::Error => theme::RED,
+    };
+    let dot_x = stripe_x + px(11.0);
+    window.paint_quad(
+        fill(Bounds { origin: point(dot_x, o.y + (hh - px(8.0)) * 0.5),
+                      size: size(px(8.0), px(8.0)) }, dot_color)
+        .corner_radii(px(4.0)),
+    );
+
+    // Name + CWD text
+    let ts = window.text_system().clone();
+    if !name.contains('\n') {
+        let run = TextRun { len: name.len(), font: font(".SystemUIFont"),
+                            color: theme::TEXT.into(), background_color: None,
+                            underline: None, strikethrough: None };
+        let shaped = ts.shape_line(name.clone(), px(13.0), &[run], None);
+        let _ = shaped.paint(point(dot_x + px(12.0), o.y + (hh - px(13.0)) * 0.5), hh, window, cx);
+    }
+    if !cwd.contains('\n') {
+        let run = TextRun { len: cwd.len(), font: font(".SystemUIFont"),
+                            color: theme::OVERLAY0.into(), background_color: None,
+                            underline: None, strikethrough: None };
+        let shaped = ts.shape_line(cwd.clone(), px(10.0), &[run], None);
+        let cwd_x = o.x + w - shaped.width - px(12.0);
+        let _ = shaped.paint(point(cwd_x, o.y + (hh - px(10.0)) * 0.5), hh, window, cx);
+    }
+
+    // Tab bar
+    let tab_y = o.y + hh;
+    window.paint_quad(fill(
+        Bounds { origin: point(o.x, tab_y), size: size(w, tbh) },
+        theme::MANTLE,
+    ));
+    window.paint_quad(fill(
+        Bounds { origin: point(o.x, tab_y + tbh - px(1.0)), size: size(w, px(1.0)) },
+        theme::SURFACE0,
+    ));
+    let mut tab_x = o.x + px(8.0);
+    for (i, label) in TAB_LABELS.iter().enumerate() {
+        let active = i == active_tab;
+        let color: Hsla = if active { accent.into() } else { theme::SUBTEXT0.into() };
+        let run = TextRun { len: label.len(), font: font(".SystemUIFont"),
+                            color, background_color: None,
+                            underline: None, strikethrough: None };
+        let shaped = ts.shape_line(SharedString::from(*label), px(11.0), &[run], None);
+        let label_y = tab_y + (tbh - px(11.0)) * 0.5;
+        let _ = shaped.paint(point(tab_x, label_y), tbh, window, cx);
+        if active {
+            window.paint_quad(fill(
+                Bounds { origin: point(tab_x, tab_y + tbh - px(3.0)),
+                         size: size(shaped.width, px(2.0)) },
+                accent,
+            ));
+        }
+        tab_x = tab_x + shaped.width + px(12.0);
+    }
+}
+
+// ── ProjectBoxHeaderElement ───────────────────────────────────────────────────
+
+/// Standalone header + tab bar element. Used when the outer container is still a div.
+/// Kept for compatibility; ProjectBoxFullElement supersedes it.
 pub struct ProjectBoxHeaderElement {
     pub id: ElementId,
     pub name: SharedString,
@@ -19,7 +136,7 @@ pub struct ProjectBoxHeaderElement {
     pub accent: Rgba,
     pub status: AgentStatus,
     pub blink_visible: Option<std::sync::Arc<std::sync::atomic::AtomicBool>>,
-    pub active_tab: usize, // 0=Model, 1=Docs, 2=Files
+    pub active_tab: usize,
 }
 
 impl IntoElement for ProjectBoxHeaderElement {
@@ -38,11 +155,11 @@ impl Element for ProjectBoxHeaderElement {
         &mut self, _id: Option<&GlobalElementId>, _iid: Option<&InspectorElementId>,
         window: &mut Window, cx: &mut App,
     ) -> (LayoutId, ()) {
-        let total_h = HEADER_HEIGHT + TAB_BAR_HEIGHT;
         let style = Style {
             size: Size {
                 width: Length::Definite(relative(1.0)),
-                height: Length::Definite(DefiniteLength::Absolute(AbsoluteLength::Pixels(px(total_h)))),
+                height: Length::Definite(DefiniteLength::Absolute(AbsoluteLength::Pixels(
+                    px(CHROME_HEIGHT)))),
             },
             flex_shrink: 0.0,
             ..Style::default()
@@ -60,106 +177,92 @@ impl Element for ProjectBoxHeaderElement {
         bounds: Bounds<Pixels>, _rl: &mut (), _pp: &mut (),
         window: &mut Window, cx: &mut App,
     ) {
-        let o = bounds.origin;
+        paint_chrome(bounds, &self.name, &self.cwd, self.accent, self.status,
-        let w = bounds.size.width;
+                     &self.blink_visible, self.active_tab, window, cx);
-        let hh = px(HEADER_HEIGHT);
+    }
-        let tbh = px(TAB_BAR_HEIGHT);
+}
 
-        // ── Header Background ──
+// ── ProjectBoxFullElement ─────────────────────────────────────────────────────
-        window.paint_quad(PaintQuad {
-            bounds: Bounds { origin: o, size: size(w, hh) },
-            corner_radii: Corners { top_left: px(6.0), top_right: px(6.0),
-                                    bottom_left: px(0.0), bottom_right: px(0.0) },
-            background: theme::MANTLE.into(),
-            border_widths: Edges::default(),
-            border_color: transparent_black(),
-            border_style: BorderStyle::default(),
-        });
 
-        // Header bottom border
+/// Single custom Element for the entire ProjectBox card (header + tabs + content).
-        window.paint_quad(fill(
+/// ProjectBox::render() returns this — no outer root div needed.
-            Bounds { origin: point(o.x, o.y + hh - px(1.0)), size: size(w, px(1.0)) },
+pub struct ProjectBoxFullElement {
-            theme::SURFACE0,
+    pub id: ElementId,
-        ));
+    pub name: SharedString,
+    pub cwd: SharedString,
+    pub accent: Rgba,
+    pub status: AgentStatus,
+    pub blink_visible: Option<std::sync::Arc<std::sync::atomic::AtomicBool>>,
+    pub active_tab: usize,
+    /// Content area div (AgentPane + TerminalView or placeholder). Moved out in
+    /// request_layout and carried as RequestLayoutState through to paint.
+    pub content: AnyElement,
+}
 
-        // Accent stripe
+impl IntoElement for ProjectBoxFullElement {
-        let stripe_x = o.x + px(12.0);
+    type Element = Self;
-        window.paint_quad(
+    fn into_element(self) -> Self { self }
-            fill(Bounds { origin: point(stripe_x, o.y + (hh - px(20.0)) * 0.5),
+}
-                          size: size(px(3.0), px(20.0)) }, self.accent)
-            .corner_radii(px(2.0)),
-        );
 
-        // Status dot
+impl Element for ProjectBoxFullElement {
-        let dot_color = match self.status {
+    /// Content AnyElement carried from request_layout → prepaint → paint.
-            AgentStatus::Running => if self.blink_visible.as_ref()
+    type RequestLayoutState = AnyElement;
-                .map(|b| b.load(Ordering::Relaxed)).unwrap_or(true)
+    type PrepaintState = ();
-                { theme::GREEN } else { theme::SURFACE1 },
+
-            AgentStatus::Idle  => theme::OVERLAY0,
+    fn id(&self) -> Option<ElementId> { Some(self.id.clone()) }
-            AgentStatus::Done  => theme::BLUE,
+    fn source_location(&self) -> Option<&'static std::panic::Location<'static>> { None }
-            AgentStatus::Error => theme::RED,
+
+    fn request_layout(
+        &mut self,
+        _id: Option<&GlobalElementId>,
+        _iid: Option<&InspectorElementId>,
+        window: &mut Window,
+        cx: &mut App,
+    ) -> (LayoutId, AnyElement) {
+        // Move content out of self so we can call request_layout on it (needs &mut self).
+        let mut content = Empty.into_any_element();
+        std::mem::swap(&mut content, &mut self.content);
+        let child_id = content.request_layout(window, cx);
+
+        // Root style: fill parent, flex-col (chrome occupies fixed top portion via paint).
+        let style = Style {
+            size: size(relative(1.0).into(), relative(1.0).into()),
+            flex_shrink: 0.0,
+            display: Display::Flex,
+            flex_direction: FlexDirection::Column,
+            ..Style::default()
         };
-        let dot_x = stripe_x + px(11.0);
+        (window.request_layout(style, [child_id], cx), content)
-        window.paint_quad(
-            fill(Bounds { origin: point(dot_x, o.y + (hh - px(8.0)) * 0.5),
-                          size: size(px(8.0), px(8.0)) }, dot_color)
-            .corner_radii(px(4.0)),
-        );
-
-        // Name text
-        let ts = window.text_system().clone();
-        if !self.name.contains('\n') {
-            let run = TextRun { len: self.name.len(), font: font(".SystemUIFont"),
-                                color: theme::TEXT.into(), background_color: None,
-                                underline: None, strikethrough: None };
-            let shaped = ts.shape_line(self.name.clone(), px(13.0), &[run], None);
-            let _ = shaped.paint(point(dot_x + px(12.0), o.y + (hh - px(13.0)) * 0.5), hh, window, cx);
     }
 
-        // CWD text (right-aligned)
+    fn prepaint(
-        if !self.cwd.contains('\n') {
+        &mut self,
-            let run = TextRun { len: self.cwd.len(), font: font(".SystemUIFont"),
+        _id: Option<&GlobalElementId>,
-                                color: theme::OVERLAY0.into(), background_color: None,
+        _iid: Option<&InspectorElementId>,
-                                underline: None, strikethrough: None };
+        bounds: Bounds<Pixels>,
-            let shaped = ts.shape_line(self.cwd.clone(), px(10.0), &[run], None);
+        content: &mut AnyElement,
-            let cwd_x = o.x + w - shaped.width - px(12.0);
+        window: &mut Window,
-            let _ = shaped.paint(point(cwd_x, o.y + (hh - px(10.0)) * 0.5), hh, window, cx);
+        cx: &mut App,
+    ) -> () {
+        // Place content below the painted chrome (header + tab bar).
+        let content_origin = point(bounds.origin.x, bounds.origin.y + px(CHROME_HEIGHT));
+        content.prepaint_at(content_origin, window, cx);
     }
 
-        // ── Tab Bar ──
+    fn paint(
-        let tab_y = o.y + hh;
+        &mut self,
-        // Tab bar background
+        _id: Option<&GlobalElementId>,
-        window.paint_quad(fill(
+        _iid: Option<&InspectorElementId>,
-            Bounds { origin: point(o.x, tab_y), size: size(w, tbh) },
+        bounds: Bounds<Pixels>,
-            theme::MANTLE,
+        content: &mut AnyElement,
-        ));
+        _pp: &mut (),
-        // Tab bar bottom border
+        window: &mut Window,
-        window.paint_quad(fill(
+        cx: &mut App,
-            Bounds { origin: point(o.x, tab_y + tbh - px(1.0)), size: size(w, px(1.0)) },
+    ) {
-            theme::SURFACE0,
+        // 1. Paint header + tabs directly.
-        ));
+        paint_chrome(bounds, &self.name, &self.cwd, self.accent, self.status,
-
+                     &self.blink_visible, self.active_tab, window, cx);
-        // Tab labels
+        // 2. Paint the content child (already prepainted at correct origin).
-        let mut tab_x = o.x + px(8.0);
+        content.paint(window, cx);
-        for (i, label) in TAB_LABELS.iter().enumerate() {
-            let active = i == self.active_tab;
-            let color: Hsla = if active { self.accent.into() } else { theme::SUBTEXT0.into() };
-            let run = TextRun { len: label.len(), font: font(".SystemUIFont"),
-                                color, background_color: None,
-                                underline: None, strikethrough: None };
-            let shaped = ts.shape_line(SharedString::from(*label), px(11.0), &[run], None);
-            let label_y = tab_y + (tbh - px(11.0)) * 0.5;
-            let _ = shaped.paint(point(tab_x, label_y), tbh, window, cx);
-
-            // Active indicator (2px underline)
-            if active {
-                window.paint_quad(fill(
-                    Bounds { origin: point(tab_x, tab_y + tbh - px(3.0)),
-                             size: size(shaped.width, px(2.0)) },
-                    self.accent,
-                ));
-            }
-            tab_x = tab_x + shaped.width + px(12.0);
-        }
     }
 }