feat(tui): add drag-to-resize sidebar width by idling11 · Pull Request #2604 · Hmbown/CodeWhale

idling11 · 2026-06-03T03:38:20Z

What: Add interactive mouse-drag resize support between the chat area and sidebar.
Previously sidebar width could only be adjusted via /config sidebar_width <percent>, requiring a typed percentage and guesswork.
How:
- Render a 1-column draggable handle (│) on the left edge of the sidebar with three visual states:
  - default — dim slate background
  - hover — orange (warning) background
  - drag — blue (accent) background
- On MouseDown on the handle → record anchor position (sidebar_resize_anchor_x, sidebar_resize_anchor_width).
- On Drag → compute delta, convert to percentage (10–50% range), update sidebar_width_percent in real time.
- On MouseUp → persist the new width to ~/.deepseek/settings.toml via Settings::save().
- Store last_sidebar_area / last_sidebar_handle_area / sidebar_resize_total_width for mouse hit-testing and percentage calculation.

Files changed:

File	Change
`crates/tui/src/tui/app.rs`	Add 7 state fields for resize drag
`crates/tui/src/tui/ui.rs`	Render handle, store layout info, persist on drag-end
`crates/tui/src/tui/mouse_ui.rs`	`handle_sidebar_resize_mouse` — Down/Drag/Up logic
`crates/tui/src/settings.rs`	`update_sidebar_width()` helper
`crates/tui/src/tui/ui/tests.rs`	5 unit tests

Tests: 5 new tests covering handle click, drag percentage calculation, 10–50% clamp, mouse-up finalization, and non-handle click.
Verification: cargo fmt --all ✅ | cargo check ✅ | cargo test -p codewhale-tui -- ui::tests (337 tests) ✅

Closes #2602

Greptile Summary

This PR adds interactive mouse-drag resizing of the TUI sidebar via a 1-column │ handle rendered on the sidebar's left edge, replacing the previous keyboard-only /config sidebar_width workflow. The drag state is tracked in App, hit-tested in mouse_ui.rs, and persisted to disk on MouseUp using the established Settings::load() + save() pattern.

Handle rendering (ui.rs): the handle is painted after the sidebar render pass with three visual states (default/hover/drag); layout rects are stored on App each frame for hit-testing.
Mouse handling (mouse_ui.rs): handle_sidebar_resize_mouse manages Down/Drag/Up events; drag fires sidebar_resizing = true and updates sidebar_width_percent in real time, with clamp(10, 50) on the percentage.
Persistence (ui.rs + settings.rs): sidebar_width_dirty is set on MouseUp; the event loop checks the flag and calls Settings::load() → update_sidebar_width → save().

Confidence Score: 4/5

Safe to merge with one fix: the stuck-resize bug when a modal opens during a drag should be addressed before shipping.

The drag-resize logic, percentage calculation, and persistence path are all correct and well-tested. The one gap is that sidebar_resizing can be left permanently true when the view-stack intercepts MouseUp while a modal is open — any subsequent drag will then silently continue from a stale anchor. The scenario is narrow but reproducible whenever a keyboard shortcut opens a modal mid-drag.

crates/tui/src/tui/mouse_ui.rs — the handle_sidebar_resize_mouse function needs a recovery path for MouseUp when the view-stack is non-empty.

Important Files Changed

Filename	Overview
crates/tui/src/tui/mouse_ui.rs	Adds `handle_sidebar_resize_mouse` for Down/Drag/Up handling; the `sidebar_resizing` flag can get stuck `true` when a modal intercepts `MouseUp` while the view-stack is non-empty.
crates/tui/src/tui/ui.rs	Renders the drag handle and stores layout rects for hit-testing; persistence is correctly wired to the MouseUp path.
crates/tui/src/tui/app.rs	Adds 7 new state fields for drag-resize; initialisation is clean and consistent with existing field patterns.
crates/tui/src/settings.rs	Adds `update_sidebar_width` helper that clamps to [10, 50] in memory; straightforward and consistent with the codebase pattern.
crates/tui/src/tui/ui/tests.rs	Adds 5 focused unit tests covering handle-click, drag-percentage math, clamping, mouse-up finalisation, and non-handle click; all test the happy path correctly.

Sequence Diagram

sequenceDiagram
    participant User
    participant EventLoop
    participant handle_sidebar_resize_mouse
    participant App
    participant Settings

    User->>EventLoop: MouseDown on handle col
    EventLoop->>handle_sidebar_resize_mouse: mouse event
    handle_sidebar_resize_mouse->>App: "sidebar_resizing=true, anchor_x/width set"
    App-->>EventLoop: "needs_redraw=true"

    User->>EventLoop: MouseDrag (left/right)
    EventLoop->>handle_sidebar_resize_mouse: mouse event
    handle_sidebar_resize_mouse->>App: compute delta → update sidebar_width_percent (clamped 10-50%)
    App-->>EventLoop: "needs_redraw=true"

    User->>EventLoop: MouseUp
    EventLoop->>handle_sidebar_resize_mouse: mouse event
    handle_sidebar_resize_mouse->>App: "sidebar_resizing=false, sidebar_width_dirty=true"
    EventLoop->>Settings: load() from disk
    Settings-->>EventLoop: settings struct
    EventLoop->>Settings: update_sidebar_width(app.sidebar_width_percent)
    EventLoop->>Settings: save() to ~/.deepseek/settings.toml

_{Reviews (2): Last reviewed commit: "## `feat(tui): add drag-to-resize sideba..." | Re-trigger Greptile}

github-actions · 2026-06-03T03:38:29Z

Thanks @idling11 for taking the time to contribute.

This repository is currently observing a maintainer-managed contribution gate in dry-run mode, so this pull request is staying open. When enforcement is enabled, pull requests from contributors who are not listed in .github/APPROVED_CONTRIBUTORS will be closed automatically.

Please read CONTRIBUTING.md for the expected contribution shape. A maintainer can grant PR access by commenting /lgtm on a pull request.

gemini-code-assist

Code Review

This pull request implements a draggable resize handle for the TUI sidebar, allowing users to dynamically adjust and persist the sidebar width percentage. The review feedback highlights a potential panic from direct buffer indexing, a layout logic issue where a hardcoded minimum width constraint conflicts with the percentage limits, and performance concerns regarding synchronous file I/O blocking the main async event loop.

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gemini-code-assist · 2026-06-03T03:40:08Z

+            let buf = f.buffer_mut();
+            for row in handle_rect.y..handle_rect.y.saturating_add(handle_rect.height) {
+                if row < buf.area().height {
+                    buf[(handle_rect.x, row)]
+                        .set_char('│')
+                        .set_style(handle_style);
+                }
+            }


Using direct indexing buf[(handle_rect.x, row)] can panic if handle_rect.x is out of bounds (e.g., during rapid terminal resizing or layout miscalculations). Using buf.get_mut(handle_rect.x, row) is safer and more idiomatic, as it returns an Option<&mut Cell> and avoids any potential panics.

let buf = f.buffer_mut(); for row in handle_rect.y..handle_rect.y.saturating_add(handle_rect.height) { if let Some(cell) = buf.get_mut(handle_rect.x, row) { cell.set_char('│') .set_style(handle_style); } }

gemini-code-assist · 2026-06-03T03:40:08Z

+        }
+        MouseEventKind::Drag(MouseButton::Left) if app.sidebar_resizing => {
+            let delta = app.sidebar_resize_anchor_x as i32 - mouse.column as i32;
+            let new_width = (app.sidebar_resize_anchor_width as i32 + delta).max(24) as u16;


The hardcoded .max(24) constraint on new_width prevents the sidebar from being resized down to the minimum 10% on standard terminal widths (e.g., on a 120-column screen, 24 columns is 20%, so the user can never reach 10%). Additionally, if the sidebar was previously smaller than 24 columns, starting a drag will cause a sudden jump to 24 columns. Consider using .max(0) or .max(1) and letting the percentage clamp (10% to 50%) handle the minimum width constraint naturally.

Suggested change

let new_width = (app.sidebar_resize_anchor_width as i32 + delta).max(24) as u16;

let new_width = (app.sidebar_resize_anchor_width as i32 + delta).max(0) as u16;

gemini-code-assist · 2026-06-03T03:40:08Z

+                // Persist sidebar width when the user finishes a drag-to-resize.
+                if app.sidebar_width_dirty {
+                    app.sidebar_width_dirty = false;
+                    if let Ok(mut settings) = Settings::load() {
+                        settings.update_sidebar_width(app.sidebar_width_percent);
+                        let _ = settings.save();
+                    }
+                }


Performing synchronous file I/O (Settings::load() and settings.save()) directly on the main async event loop thread can block the executor and cause noticeable UI stuttering or lag when the user finishes dragging. Consider offloading this blocking operation to a background thread using tokio::task::spawn_blocking.

// Persist sidebar width when the user finishes a drag-to-resize. if app.sidebar_width_dirty { app.sidebar_width_dirty = false; let percent = app.sidebar_width_percent; tokio::task::spawn_blocking(move || { if let Ok(mut settings) = Settings::load() { settings.update_sidebar_width(percent); let _ = settings.save(); } }); }

gemini-code-assist · 2026-06-03T03:40:08Z

+                if app.sidebar_width_dirty {
+                    app.sidebar_width_dirty = false;
+                    if let Ok(mut settings) = Settings::load() {
+                        settings.update_sidebar_width(app.sidebar_width_percent);
+                        let _ = settings.save();
+                    }
+                }
                continue;


Performing synchronous file I/O (Settings::load() and settings.save()) directly on the main async event loop thread can block the executor and cause noticeable UI stuttering or lag when the user finishes dragging. Consider offloading this blocking operation to a background thread using tokio::task::spawn_blocking.

// Persist sidebar width when the user finishes a drag-to-resize. if app.sidebar_width_dirty { app.sidebar_width_dirty = false; let percent = app.sidebar_width_percent; tokio::task::spawn_blocking(move || { if let Ok(mut settings) = Settings::load() { settings.update_sidebar_width(percent); let _ = settings.save(); } }); }

- **What:** Add interactive mouse-drag resize support between the chat area and sidebar. Previously sidebar width could only be adjusted via `/config sidebar_width <percent>`, requiring a typed percentage and guesswork. - **How:** - Render a **1-column draggable handle** (`│`) on the left edge of the sidebar with three visual states: - **default** — dim slate background - **hover** — orange (warning) background - **drag** — blue (accent) background - On `MouseDown` on the handle → record anchor position (`sidebar_resize_anchor_x`, `sidebar_resize_anchor_width`). - On `Drag` → compute delta, convert to percentage (10–50% range), update `sidebar_width_percent` in real time. - On `MouseUp` → persist the new width to `~/.deepseek/settings.toml` via `Settings::save()`. - Store `last_sidebar_area` / `last_sidebar_handle_area` / `sidebar_resize_total_width` for mouse hit-testing and percentage calculation. - **Files changed:** | File | Change | |------|--------| | `crates/tui/src/tui/app.rs` | Add 7 state fields for resize drag | | `crates/tui/src/tui/ui.rs` | Render handle, store layout info, persist on drag-end | | `crates/tui/src/tui/mouse_ui.rs` | `handle_sidebar_resize_mouse` — Down/Drag/Up logic | | `crates/tui/src/settings.rs` | `update_sidebar_width()` helper | | `crates/tui/src/tui/ui/tests.rs` | 5 unit tests | - **Tests:** 5 new tests covering handle click, drag percentage calculation, 10–50% clamp, mouse-up finalization, and non-handle click. - **Verification:** `cargo fmt --all` ✅ | `cargo check` ✅ | `cargo test -p codewhale-tui -- ui::tests` (337 tests) ✅ Closes Hmbown#2602

greptile-apps · 2026-06-03T03:46:57Z

+fn handle_sidebar_resize_mouse(app: &mut App, mouse: MouseEvent) -> bool {
+    let Some(handle) = app.last_sidebar_handle_area else {
+        return false;
+    };
+
+    let hit = mouse.column == handle.x
+        && mouse.row >= handle.y
+        && mouse.row < handle.y.saturating_add(handle.height);
+
+    match mouse.kind {
+        MouseEventKind::Down(MouseButton::Left) if hit => {
+            app.sidebar_resizing = true;
+            app.sidebar_resize_anchor_x = mouse.column;
+            app.sidebar_resize_anchor_width = app.last_sidebar_area.map(|a| a.width).unwrap_or(28);
+            app.needs_redraw = true;
+            true
+        }
+        MouseEventKind::Drag(MouseButton::Left) if app.sidebar_resizing => {
+            let delta = app.sidebar_resize_anchor_x as i32 - mouse.column as i32;
+            let new_width = (app.sidebar_resize_anchor_width as i32 + delta).max(24) as u16;
+            let total = app.sidebar_resize_total_width.max(1);
+            let new_pct = ((new_width as u32 * 100) / total as u32).clamp(10, 50) as u16;
+            if new_pct != app.sidebar_width_percent {
+                app.sidebar_width_percent = new_pct;
+                app.needs_redraw = true;
+            }
+            true
+        }
+        MouseEventKind::Up(MouseButton::Left) if app.sidebar_resizing => {
+            app.sidebar_resizing = false;
+            app.sidebar_width_dirty = true;
+            app.needs_redraw = true;
+            true
+        }
+        _ => false,
+    }
+}


Stale handle rect when sidebar is hidden

last_sidebar_handle_area and last_sidebar_area are only written inside if let Some(sidebar_area) = sidebar_area { … } in the render function, so they are never cleared when sidebar_focus == SidebarFocus::Hidden or when the terminal shrinks below SIDEBAR_VISIBLE_MIN_WIDTH. A click at the coordinates that the handle occupied before it disappeared will still pass the hit-test here and begin a resize drag against an invisible sidebar, silently mutating sidebar_width_percent with no visual feedback.

Fix: clear both fields (and abort any active drag) when the sidebar is not rendered:

// in the render fn, in the else branch where sidebar is absent app.last_sidebar_handle_area = None; app.last_sidebar_area = None; app.sidebar_resizing = false;

Then the early-return let Some(handle) = app.last_sidebar_handle_area else { return false; } will correctly bail out.

greptile-apps · 2026-06-03T03:46:58Z

+                // Persist sidebar width when the user finishes a drag-to-resize.
+                if app.sidebar_width_dirty {
+                    app.sidebar_width_dirty = false;
+                    if let Ok(mut settings) = Settings::load() {
+                        settings.update_sidebar_width(app.sidebar_width_percent);
+                        let _ = settings.save();
+                    }
+                }


Dead persistence check in the key-event branch

sidebar_width_dirty is only ever set to true inside handle_sidebar_resize_mouse on a MouseUp event. When a mouse-up fires, the first copy of this block (around line 2602) clears the flag and saves before continue-ing to the next iteration. By the time a key event is processed (this branch), the flag is always false. This block is unreachable in practice and just adds noise; it can be removed.

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

The sidebar Work panel reads checklist data from `app.todos` (`tokio::sync::Mutex`) via non-blocking `try_lock()`. When the engine holds the lock (executing `checklist_write` in a tokio task), the panel silently resets to "Work state updating..." and discards all prior data. The Tasks panel does not suffer from this because it reads plain App fields (no lock needed). Fix: cache the last successful `SidebarWorkSummary` in `App` and return it when `try_lock()` fails. Live hunt/goal fields (quarry, verdict, cycle count, token usage) are still refreshed from the current App state on every frame, even during cache fallback. - Make `SidebarWorkSummary`, `SidebarWorkChecklistItem`, `SidebarWorkStrategyStep` pub(crate) so App can store them. - Add `cached_work_summary: Option<SidebarWorkSummary>` to App. - Rewrite `sidebar_work_summary(&mut App)` to use a fallback chain: fresh locks → cache → state_updating empty state. - Add 4 unit tests covering cache populate, lock-busy fallback, no-cache+lock fallback, and live-field refresh during fallback. Closes Hmbown#2604

idling11 changed the title ~~## feat(tui): add drag-to-resize sidebar width~~ feat(tui): add drag-to-resize sidebar width Jun 3, 2026

gemini-code-assist Bot reviewed Jun 3, 2026

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greptile-apps Bot reviewed Jun 3, 2026

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idling11 force-pushed the feature/sidebar-resize-drag branch from 564a0ae to adf3fe2 Compare June 3, 2026 03:47

Hmbown merged commit 1781312 into Hmbown:main Jun 3, 2026
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feat(tui): add drag-to-resize sidebar width#2604

feat(tui): add drag-to-resize sidebar width#2604
Hmbown merged 1 commit into
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idling11:feature/sidebar-resize-drag

idling11 commented Jun 3, 2026 •

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	let new_width = (app.sidebar_resize_anchor_width as i32 + delta).max(24) as u16;
	let new_width = (app.sidebar_resize_anchor_width as i32 + delta).max(0) as u16;

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Greptile Summary

Confidence Score: 4/5

Important Files Changed

Sequence Diagram

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idling11 commented Jun 3, 2026 •

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