feat: Implement hierarchical sidebar with projects and tags

Add complete sidebar implementation with:
- ProjectTree model using arena allocator for hierarchical projects
- FilterState model for global filter state management
- Sidebar view with independent scrollable sections
- Project tree with expand/collapse functionality
- Tag selection with toggle support
- Observable filter state shared across components

src/app.rs

@@ -1,14 +1,13 @@
 use gpui::prelude::*;
-use std::sync::Arc;
 
-use crate::components::{
-    self,
-    input::{Input, Suggestion},
-};
+use crate::models::{FilterState, ProjectTree};
+use crate::theme::ActiveTheme;
+use crate::view::sidebar::{Sidebar, TagItem};
+use gpui::div;
 
 pub(crate) struct App {
-    input: gpui::Entity<Input>,
-    current_text: gpui::SharedString,
+    sidebar: gpui::Entity<Sidebar>,
+    filter_state: gpui::Entity<FilterState>,
 }
 
 impl gpui::Render for App {
@@ -17,12 +16,26 @@ impl gpui::Render for App {
         _window: &mut gpui::Window,
         _cx: &mut gpui::Context<Self>,
     ) -> impl gpui::IntoElement {
-        components::panel::Panel::new()
-            .child(self.input.clone())
-            .child(components::label::Label::new(format!(
-                "Text: {}",
-                &self.current_text
-            )))
+        let theme = _cx.theme();
+
+        div()
+            .flex()
+            .size_full()
+            .bg(theme.background)
+            .child(div().w(gpui::px(250.)).h_full().child(self.sidebar.clone()))
+            .child(
+                div()
+                    .flex_1()
+                    .h_full()
+                    .flex()
+                    .items_center()
+                    .justify_center()
+                    .child(
+                        div()
+                            .text_color(theme.muted)
+                            .child("Main panel - TaskTable will go here"),
+                    ),
+            )
     }
 }
 
@@ -36,42 +49,62 @@ impl App {
                 gpui::WindowOptions::default(),
                 |_window: &mut gpui::Window, app: &mut gpui::App| {
                     app.new(|cx: &mut gpui::Context<'_, App>| {
-                        let input = cx.new(|cx| {
-                            Input::new("input", cx, "Type here...").with_suggest(Arc::new(|text| {
-                                let suggestions = vec![
-                                    ("project:", "Filter by project"),
-                                    ("+work", "Tag: work"),
-                                    ("+personal", "Tag: personal"),
-                                    ("due:today", "Tasks for today"),
-                                    ("due:tomorrow", "Tasks for tomorrow"),
-                                    ("priority:H", "Priority high"),
-                                    ("priority:M", "Priority medium"),
-                                    ("priority:L", "Priority low"),
-                                ];
+                        let filter_state = cx.new(|_cx| FilterState::new());
 
-                                suggestions
-                                    .into_iter()
-                                    .filter(|(insert, _)| {
-                                        text.is_empty()
-                                            || insert.to_lowercase().contains(&text.to_lowercase())
-                                    })
-                                    .map(|(insert, label)| {
-                                        Suggestion::new(format!("{} - {}", insert, label), insert)
-                                    })
-                                    .collect()
-                            }))
+                        let mut project_tree = ProjectTree::new();
+                        project_tree.build_from_projects(&[
+                            ("Work.Backend.API".to_string(), 5),
+                            ("Work.Backend.DB".to_string(), 7),
+                            ("Work.Frontend.React".to_string(), 3),
+                            ("Work.Frontend.Styling".to_string(), 2),
+                            ("Home.Kitchen".to_string(), 4),
+                            ("Home.Garden".to_string(), 2),
+                            ("ignis.v0.1.phase0".to_string(), 15),
+                            ("free-ai".to_string(), 2),
+                        ]);
+
+                        project_tree.expand_path("Work");
+                        project_tree.expand_path("Work.Backend");
+
+                        let tags = vec![
+                            TagItem {
+                                name: "parser".to_string(),
+                                task_count: 8,
+                            },
+                            TagItem {
+                                name: "cli".to_string(),
+                                task_count: 5,
+                            },
+                            TagItem {
+                                name: "testing".to_string(),
+                                task_count: 6,
+                            },
+                            TagItem {
+                                name: "diagnostics".to_string(),
+                                task_count: 7,
+                            },
+                            TagItem {
+                                name: "analyzer".to_string(),
+                                task_count: 3,
+                            },
+                        ];
+
+                        let sidebar = cx.new(|cx| {
+                            Sidebar::new(project_tree, tags, filter_state.clone(), cx)
+                                .on_filter_change(|filter, _window, _cx| {
+                                    println!("Filter changed:");
+                                    if let Some(ref project) = filter.selected_project {
+                                        println!("  Project: {}", project);
+                                    } else {
+                                        println!("  Project: All");
+                                    }
+                                    println!("  Active tags: {:?}", filter.active_tags);
+                                })
                         });
 
-                        cx.observe(&input, |this, input, cx| {
-                            let value = input.read(cx).value().to_string();
-                            this.current_text = value.into();
-                            cx.notify();
-                        })
-                        .detach();
-
                         App {
-                            input,
-                            current_text: "".into(),
+                            sidebar,
+                            filter_state,
                         }
                     })
                 },

src/components/panel.rs

@@ -70,7 +70,15 @@ impl gpui::RenderOnce for Panel {
             .content
             .drain(..)
             .enumerate()
-            .map(|(ix, c)| gpui::div().id(ix).child(c).into_any_element())
+            .map(|(ix, c)| {
+                gpui::div()
+                    .id(ix)
+                    .flex()
+                    .flex_col()
+                    .flex_1()
+                    .child(c)
+                    .into_any_element()
+            })
             .collect();
 
         gpui::div()
@@ -82,6 +90,7 @@ impl gpui::RenderOnce for Panel {
             .p(gpui::px(self.padding))
             .flex()
             .flex_col()
+            .h_full()
             .children(header)
             .children(children)
     }

src/main.rs

@@ -2,7 +2,9 @@ use crate::app::App;
 
 mod app;
 mod components;
+mod models;
 mod theme;
+mod view;
 
 fn main() {
     App::run();

src/models/filter_state.rs

@@ -0,0 +1,152 @@
+use std::collections::HashSet;
+
+#[derive(Debug, Clone, Default)]
+pub struct FilterState {
+    pub selected_project: Option<String>,
+    pub active_tags: HashSet<String>,
+    pub search_text: String,
+    pub status_filter: StatusFilter,
+    pub priority_filter: PriorityFilter,
+    pub due_filter: DueFilter,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum StatusFilter {
+    All,
+    Pending,
+    Completed,
+    Waiting,
+    Deleted,
+}
+
+impl Default for StatusFilter {
+    fn default() -> Self {
+        Self::Pending
+    }
+}
+
+impl StatusFilter {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            Self::All => "All",
+            Self::Pending => "Pending",
+            Self::Completed => "Completed",
+            Self::Waiting => "Waiting",
+            Self::Deleted => "Deleted",
+        }
+    }
+
+    pub fn all_variants() -> &'static [Self] {
+        &[
+            Self::All,
+            Self::Pending,
+            Self::Completed,
+            Self::Waiting,
+            Self::Deleted,
+        ]
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum PriorityFilter {
+    All,
+    High,
+    Medium,
+    Low,
+    None,
+}
+
+impl Default for PriorityFilter {
+    fn default() -> Self {
+        Self::All
+    }
+}
+
+impl PriorityFilter {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            Self::All => "All",
+            Self::High => "High (H)",
+            Self::Medium => "Medium (M)",
+            Self::Low => "Low (L)",
+            Self::None => "None",
+        }
+    }
+
+    pub fn all_variants() -> &'static [Self] {
+        &[Self::All, Self::High, Self::Medium, Self::Low, Self::None]
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum DueFilter {
+    All,
+    Overdue,
+    Today,
+    ThisWeek,
+    NoDate,
+}
+
+impl Default for DueFilter {
+    fn default() -> Self {
+        Self::All
+    }
+}
+
+impl DueFilter {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            Self::All => "All",
+            Self::Overdue => "Overdue",
+            Self::Today => "Today",
+            Self::ThisWeek => "This Week",
+            Self::NoDate => "No Date",
+        }
+    }
+
+    pub fn all_variants() -> &'static [Self] {
+        &[
+            Self::All,
+            Self::Overdue,
+            Self::Today,
+            Self::ThisWeek,
+            Self::NoDate,
+        ]
+    }
+}
+
+impl FilterState {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    pub fn select_project(&mut self, project: Option<String>) {
+        self.selected_project = project;
+    }
+
+    pub fn toggle_tag(&mut self, tag: String) {
+        if self.active_tags.contains(&tag) {
+            self.active_tags.remove(&tag);
+        } else {
+            self.active_tags.insert(tag);
+        }
+    }
+
+    pub fn clear(&mut self) {
+        self.selected_project = None;
+        self.active_tags.clear();
+        self.search_text.clear();
+        self.status_filter = StatusFilter::default();
+        self.priority_filter = PriorityFilter::default();
+        self.due_filter = DueFilter::default();
+    }
+
+    pub fn has_active_filters(&self) -> bool {
+        self.selected_project.is_some()
+            || !self.active_tags.is_empty()
+            || !self.search_text.is_empty()
+            || self.status_filter != StatusFilter::default()
+            || self.priority_filter != PriorityFilter::default()
+            || self.due_filter != DueFilter::default()
+    }
+}

src/models/mod.rs

@@ -0,0 +1,5 @@
+pub mod filter_state;
+pub mod project_tree;
+
+pub use filter_state::*;
+pub use project_tree::*;

src/models/project_tree.rs

@@ -0,0 +1,266 @@
+use std::collections::HashMap;
+
+#[derive(Debug, Clone)]
+pub struct ProjectNode {
+    pub name: String,
+    pub full_path: String,
+    pub task_count: usize,
+    pub direct_task_count: usize,
+    pub level: usize,
+    pub children_indices: Vec<usize>,
+    pub is_expanded: bool,
+}
+
+impl ProjectNode {
+    pub fn new(name: String, full_path: String, level: usize) -> Self {
+        Self {
+            name,
+            full_path,
+            task_count: 0,
+            direct_task_count: 0,
+            level,
+            children_indices: Vec::new(),
+            is_expanded: false,
+        }
+    }
+
+    #[inline]
+    pub fn has_children(&self) -> bool {
+        !self.children_indices.is_empty()
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct ProjectTree {
+    nodes: Vec<ProjectNode>,
+    root_indices: Vec<usize>,
+    path_to_index: HashMap<String, usize>,
+    expanded_paths: HashMap<String, bool>,
+}
+
+impl ProjectTree {
+    pub fn new() -> Self {
+        Self {
+            nodes: Vec::new(),
+            root_indices: Vec::new(),
+            path_to_index: HashMap::new(),
+            expanded_paths: HashMap::new(),
+        }
+    }
+
+    pub fn build_from_projects(&mut self, projects: &[(String, usize)]) {
+        self.nodes.clear();
+        self.root_indices.clear();
+        self.path_to_index.clear();
+
+        for (project_path, task_count) in projects {
+            if project_path.is_empty() {
+                continue;
+            }
+
+            let segments: Vec<&str> = project_path.split('.').collect();
+            self.insert_project(&segments, task_count);
+        }
+
+        self.root_indices.sort_by(|a, b| {
+            self.nodes[*a]
+                .name
+                .to_lowercase()
+                .cmp(&self.nodes[*b].name.to_lowercase())
+        });
+
+        let nodes_len = self.nodes.len();
+        for i in 0..nodes_len {
+            let mut indices_with_names: Vec<_> = self.nodes[i]
+                .children_indices
+                .iter()
+                .map(|&idx| (idx, self.nodes[idx].name.to_lowercase()))
+                .collect();
+            indices_with_names.sort_by(|a, b| a.1.cmp(&b.1));
+            self.nodes[i].children_indices =
+                indices_with_names.into_iter().map(|(idx, _)| idx).collect();
+        }
+
+        for (path, is_expanded) in &self.expanded_paths {
+            if let Some(&idx) = self.path_to_index.get(path) {
+                self.nodes[idx].is_expanded = *is_expanded;
+            }
+        }
+    }
+
+    fn insert_project(&mut self, segments: &[&str], task_count: &usize) {
+        if segments.is_empty() {
+            return;
+        }
+
+        let mut current_path = String::new();
+        let mut parent_idx: Option<usize> = None;
+
+        for (level, &segment) in segments.iter().enumerate() {
+            if !current_path.is_empty() {
+                current_path.push('.');
+            }
+            current_path.push_str(segment);
+
+            let node_idx = if let Some(&idx) = self.path_to_index.get(&current_path) {
+                idx
+            } else {
+                let new_idx = self.nodes.len();
+                let is_expanded = self
+                    .expanded_paths
+                    .get(&current_path)
+                    .copied()
+                    .unwrap_or(false);
+
+                let node = ProjectNode {
+                    name: segment.to_string(),
+                    full_path: current_path.clone(),
+                    task_count: 0,
+                    direct_task_count: 0,
+                    level,
+                    children_indices: Vec::new(),
+                    is_expanded,
+                };
+
+                self.nodes.push(node);
+                self.path_to_index.insert(current_path.clone(), new_idx);
+
+                if let Some(parent) = parent_idx {
+                    self.nodes[parent].children_indices.push(new_idx);
+                } else {
+                    self.root_indices.push(new_idx);
+                }
+
+                new_idx
+            };
+
+            self.nodes[node_idx].task_count += task_count;
+
+            if level == segments.len() - 1 {
+                self.nodes[node_idx].direct_task_count += task_count;
+            }
+
+            parent_idx = Some(node_idx);
+        }
+    }
+
+    pub fn toggle_expansion(&mut self, full_path: &str) {
+        if let Some(&idx) = self.path_to_index.get(full_path) {
+            let new_state = !self.nodes[idx].is_expanded;
+            self.nodes[idx].is_expanded = new_state;
+            self.expanded_paths.insert(full_path.to_string(), new_state);
+        }
+    }
+
+    pub fn expand_path(&mut self, full_path: &str) {
+        let segments: Vec<&str> = full_path.split('.').collect();
+        let mut current_path = String::new();
+
+        for segment in segments {
+            if !current_path.is_empty() {
+                current_path.push('.');
+            }
+            current_path.push_str(segment);
+
+            if let Some(&idx) = self.path_to_index.get(&current_path) {
+                self.nodes[idx].is_expanded = true;
+                self.expanded_paths.insert(current_path.clone(), true);
+            }
+        }
+    }
+
+    pub fn collapse_all(&mut self) {
+        for node in &mut self.nodes {
+            node.is_expanded = false;
+        }
+        self.expanded_paths.clear();
+    }
+
+    pub fn root_indices(&self) -> &[usize] {
+        &self.root_indices
+    }
+
+    pub fn get_node(&self, idx: usize) -> Option<&ProjectNode> {
+        self.nodes.get(idx)
+    }
+
+    pub fn get_node_mut(&mut self, idx: usize) -> Option<&mut ProjectNode> {
+        self.nodes.get_mut(idx)
+    }
+
+    pub fn find_by_path(&self, path: &str) -> Option<&ProjectNode> {
+        self.path_to_index
+            .get(path)
+            .and_then(|&idx| self.nodes.get(idx))
+    }
+
+    pub fn iter_visible(&self) -> Vec<(usize, &ProjectNode)> {
+        let mut result = Vec::new();
+        for &root_idx in &self.root_indices {
+            self.collect_visible(root_idx, &mut result);
+        }
+        result
+    }
+
+    fn collect_visible<'a>(&'a self, idx: usize, result: &mut Vec<(usize, &'a ProjectNode)>) {
+        if let Some(node) = self.nodes.get(idx) {
+            result.push((idx, node));
+
+            if node.is_expanded {
+                for &child_idx in &node.children_indices {
+                    self.collect_visible(child_idx, result);
+                }
+            }
+        }
+    }
+}
+
+impl Default for ProjectTree {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_build_simple_tree() {
+        let mut tree = ProjectTree::new();
+        tree.build_from_projects(&[("Work".to_string(), 5), ("Home".to_string(), 3)]);
+
+        assert_eq!(tree.root_indices().len(), 2);
+    }
+
+    #[test]
+    fn test_build_nested_tree() {
+        let mut tree = ProjectTree::new();
+        tree.build_from_projects(&[
+            ("Work.Backend.API".to_string(), 2),
+            ("Work.Backend.DB".to_string(), 3),
+            ("Work.Frontend".to_string(), 5),
+        ]);
+
+        let work_node = tree.find_by_path("Work").unwrap();
+        assert_eq!(work_node.task_count, 10);
+        assert_eq!(work_node.direct_task_count, 0);
+
+        let backend_node = tree.find_by_path("Work.Backend").unwrap();
+        assert_eq!(backend_node.task_count, 5);
+    }
+
+    #[test]
+    fn test_toggle_expansion() {
+        let mut tree = ProjectTree::new();
+        tree.build_from_projects(&[("Work.Backend".to_string(), 5)]);
+
+        assert!(!tree.find_by_path("Work").unwrap().is_expanded);
+
+        tree.toggle_expansion("Work");
+        assert!(tree.find_by_path("Work").unwrap().is_expanded);
+
+        tree.toggle_expansion("Work");
+        assert!(!tree.find_by_path("Work").unwrap().is_expanded);
+    }
+}

src/view/mod.rs

@@ -0,0 +1 @@
+pub mod sidebar;

src/view/sidebar.rs

@@ -0,0 +1,345 @@
+use crate::components::{divider::Divider, panel::Panel};
+use crate::models::{FilterState, ProjectTree};
+use crate::theme::ActiveTheme;
+use gpui::{Context, Div, Entity, IntoElement, Window, div, prelude::*, px};
+use std::sync::Arc;
+
+#[derive(Debug, Clone)]
+pub struct TagItem {
+    pub name: String,
+    pub task_count: usize,
+}
+
+pub struct Sidebar {
+    project_tree: ProjectTree,
+    tags: Vec<TagItem>,
+    filter_state: Entity<FilterState>,
+    on_filter_change: Option<Arc<dyn Fn(FilterState, &mut Window, &mut Context<Self>) + 'static>>,
+}
+
+impl Sidebar {
+    pub fn new(
+        project_tree: ProjectTree,
+        tags: Vec<TagItem>,
+        filter_state: Entity<FilterState>,
+        cx: &mut Context<Self>,
+    ) -> Self {
+        cx.observe(&filter_state, |_sidebar, _filter, cx| {
+            cx.notify();
+        })
+        .detach();
+
+        Self {
+            project_tree,
+            tags,
+            filter_state,
+            on_filter_change: None,
+        }
+    }
+
+    pub fn on_filter_change<F>(mut self, callback: F) -> Self
+    where
+        F: Fn(FilterState, &mut Window, &mut Context<Self>) + 'static,
+    {
+        self.on_filter_change = Some(Arc::new(callback));
+        self
+    }
+
+    pub fn update_projects(&mut self, project_tree: ProjectTree, cx: &mut Context<Self>) {
+        self.project_tree = project_tree;
+        cx.notify();
+    }
+
+    pub fn update_tags(&mut self, tags: Vec<TagItem>, cx: &mut Context<Self>) {
+        self.tags = tags;
+        cx.notify();
+    }
+
+    fn handle_project_click(
+        &mut self,
+        full_path: Option<String>,
+        window: &mut Window,
+        cx: &mut Context<Self>,
+    ) {
+        self.filter_state.update(cx, |filter, _cx| {
+            filter.select_project(full_path);
+        });
+
+        if let Some(callback) = &self.on_filter_change {
+            let filter = self.filter_state.read(cx).clone();
+            callback(filter, window, cx);
+        }
+
+        cx.notify();
+    }
+
+    fn handle_expand_toggle(&mut self, full_path: String, cx: &mut Context<Self>) {
+        self.project_tree.toggle_expansion(&full_path);
+        cx.notify();
+    }
+
+    fn handle_tag_click(&mut self, tag_name: String, window: &mut Window, cx: &mut Context<Self>) {
+        self.filter_state.update(cx, |filter, _cx| {
+            filter.toggle_tag(tag_name);
+        });
+
+        if let Some(callback) = &self.on_filter_change {
+            let filter = self.filter_state.read(cx).clone();
+            callback(filter, window, cx);
+        }
+
+        cx.notify();
+    }
+
+    fn render_projects(&self, cx: &mut Context<Self>) -> Vec<Div> {
+        let theme = cx.theme();
+        let filter = self.filter_state.read(cx);
+        let mut elements = Vec::new();
+
+        let is_all_selected = filter.selected_project.is_none();
+        elements.push(
+            div()
+                .flex()
+                .items_center()
+                .gap_2()
+                .px_3()
+                .py_1()
+                .cursor_pointer()
+                .when(is_all_selected, |this| this.bg(theme.selection))
+                .hover(|style| style.bg(theme.panel))
+                .on_mouse_down(
+                    gpui::MouseButton::Left,
+                    cx.listener(|view, _event, window, cx| {
+                        view.handle_project_click(None, window, cx);
+                    }),
+                )
+                .child(
+                    div()
+                        .w_3()
+                        .h_3()
+                        .rounded_full()
+                        .border_1()
+                        .border_color(theme.accent)
+                        .when(is_all_selected, |this| this.bg(theme.accent)),
+                )
+                .child(
+                    div()
+                        .text_color(if is_all_selected {
+                            theme.foreground
+                        } else {
+                            theme.muted
+                        })
+                        .child("All"),
+                ),
+        );
+
+        for (_idx, node) in self.project_tree.iter_visible() {
+            let is_selected = filter
+                .selected_project
+                .as_ref()
+                .map(|p| p == &node.full_path)
+                .unwrap_or(false);
+
+            let indent = node.level * 16;
+            let full_path = node.full_path.clone();
+            let full_path_for_expand = node.full_path.clone();
+            let has_children = node.has_children();
+            let is_expanded = node.is_expanded;
+
+            elements.push(
+                div()
+                    .flex()
+                    .items_center()
+                    .gap_1()
+                    .px_3()
+                    .py_1()
+                    .cursor_pointer()
+                    .when(is_selected, |this| this.bg(theme.selection))
+                    .hover(|style| style.bg(theme.panel))
+                    .child(div().w(px(indent as f32)))
+                    .child(
+                        div()
+                            .w_4()
+                            .h_4()
+                            .flex()
+                            .items_center()
+                            .justify_center()
+                            .when(has_children, |this| {
+                                this.on_mouse_down(
+                                    gpui::MouseButton::Left,
+                                    cx.listener(move |view, _event, _window, cx| {
+                                        view.handle_expand_toggle(full_path_for_expand.clone(), cx);
+                                    }),
+                                )
+                            })
+                            .child(if has_children {
+                                div()
+                                    .text_color(theme.muted)
+                                    .text_xs()
+                                    .child(if is_expanded { "▼" } else { "▶" })
+                            } else {
+                                div()
+                            }),
+                    )
+                    .child(
+                        div()
+                            .flex()
+                            .flex_1()
+                            .items_center()
+                            .gap_2()
+                            .on_mouse_down(
+                                gpui::MouseButton::Left,
+                                cx.listener(move |view, _event, window, cx| {
+                                    view.handle_project_click(Some(full_path.clone()), window, cx);
+                                }),
+                            )
+                            .child(
+                                div()
+                                    .w_3()
+                                    .h_3()
+                                    .rounded_full()
+                                    .border_1()
+                                    .border_color(theme.accent)
+                                    .when(is_selected, |this| this.bg(theme.accent)),
+                            )
+                            .child(
+                                div()
+                                    .text_color(if is_selected {
+                                        theme.foreground
+                                    } else {
+                                        theme.muted
+                                    })
+                                    .child(format!("{} ({})", node.name, node.task_count)),
+                            ),
+                    ),
+            );
+        }
+
+        elements
+    }
+
+    fn render_tags(&self, cx: &mut Context<Self>) -> Vec<Div> {
+        let theme = cx.theme();
+        let filter = self.filter_state.read(cx);
+        let mut elements = Vec::new();
+
+        for tag in &self.tags {
+            let is_active = filter.active_tags.contains(&tag.name);
+            let tag_name = tag.name.clone();
+
+            elements.push(
+                div()
+                    .flex()
+                    .items_center()
+                    .gap_2()
+                    .px_3()
+                    .py_1()
+                    .cursor_pointer()
+                    .when(is_active, |this| this.bg(theme.selection))
+                    .hover(|style| style.bg(theme.panel))
+                    .on_mouse_down(
+                        gpui::MouseButton::Left,
+                        cx.listener(move |view, _event, window, cx| {
+                            view.handle_tag_click(tag_name.clone(), window, cx);
+                        }),
+                    )
+                    .child(
+                        div()
+                            .w_3()
+                            .h_3()
+                            .rounded_sm()
+                            .border_1()
+                            .border_color(theme.accent)
+                            .when(is_active, |this| {
+                                this.bg(theme.accent)
+                                    .flex()
+                                    .items_center()
+                                    .justify_center()
+                                    .child(div().text_color(theme.background).text_xs().child("✓"))
+                            }),
+                    )
+                    .child(
+                        div()
+                            .text_color(if is_active {
+                                theme.foreground
+                            } else {
+                                theme.muted
+                            })
+                            .child(format!("{} ({})", tag.name, tag.task_count)),
+                    ),
+            );
+        }
+
+        elements
+    }
+}
+
+impl Render for Sidebar {
+    fn render(&mut self, _window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
+        let theme = cx.theme().clone();
+        let projects = self.render_projects(cx);
+        let tags = self.render_tags(cx);
+
+        Panel::new().border(1.0).padding(0.0).child(
+            div()
+                .flex()
+                .flex_col()
+                .h_full()
+                .bg(theme.background)
+                .child(
+                    div()
+                        .px_3()
+                        .py_2()
+                        .border_b_1()
+                        .border_color(theme.border)
+                        .child(
+                            div()
+                                .text_sm()
+                                .font_weight(gpui::FontWeight::BOLD)
+                                .text_color(theme.foreground)
+                                .child("PROJECTS"),
+                        ),
+                )
+                .child(
+                    div()
+                        .id("sidebar-projects")
+                        .flex()
+                        .flex_col()
+                        .flex_1()
+                        .py_2()
+                        .overflow_y_scroll()
+                        .scrollbar_width(gpui::px(6.0))
+                        .children(projects),
+                )
+                .child(div().px_3().py_2().child(Divider::new(
+                    theme.border,
+                    crate::components::divider::DividerDirection::Horizontal,
+                )))
+                .child(
+                    div()
+                        .px_3()
+                        .py_2()
+                        .border_b_1()
+                        .border_color(theme.border)
+                        .child(
+                            div()
+                                .text_sm()
+                                .font_weight(gpui::FontWeight::BOLD)
+                                .text_color(theme.foreground)
+                                .child("TAGS"),
+                        ),
+                )
+                .child(
+                    div()
+                        .id("sidebar-tags")
+                        .flex()
+                        .flex_col()
+                        .flex_1()
+                        .py_2()
+                        .overflow_y_scroll()
+                        .scrollbar_width(gpui::px(6.0))
+                        .children(tags),
+                ),
+        )
+    }
+}