feat(claudbg-6gx6): TUI c key toggles color globally

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.beans/claudbg-6gx6--tui-color-toggle-with-c-key.md

@@ -0,0 +1,21 @@
+---
+# claudbg-6gx6
+title: 'TUI: color toggle with ''c'' key'
+status: completed
+type: task
+priority: normal
+created_at: 2026-03-31T00:33:01Z
+updated_at: 2026-03-31T04:32:25Z
+parent: claudbg-qpfe
+---
+
+In the TUI, pressing `c` toggles color coding on/off globally (affects all transcript views). Color is on by default unless NO_COLOR is set. The toggle state persists for the duration of the TUI session.
+
+## Summary of Changes
+
+Added a global color toggle to the TUI, activated with the `c` key:
+
+- **`src/tui/state.rs`**: Added `color_enabled: bool` field to `AppState`. Initialised in `AppState::new()` by checking the `NO_COLOR` env var (false if set and non-empty, true otherwise). Added tests for both cases.
+- **`src/tui/run.rs`**: Added `KeyCode::Char('c')` to the global event fallback handler to toggle `state.color_enabled`. Added a test for the toggle.
+- **`src/tui/screens/transcript.rs`**: Updated `build_chat_lines` to accept a `color_enabled: bool` parameter and conditionally apply ratatui `Style` colours to role labels (orange for assistant, grey for user), tool-use lines (cyan), tool-result lines (green/red), and image lines (yellow). When `color_enabled` is false, all spans use `Style::default()`. Updated the call site in `render_transcript` to pass `state.color_enabled`. Updated all test calls to pass `false`.
+- **`src/tui/modals/help_modal.rs`**: Added `c  toggle color` line to `HELP_TEXT` and bumped `DIALOG_HEIGHT` from 14 to 15 to accommodate it.

src/tui/modals/help_modal.rs

@@ -16,7 +16,7 @@ use crate::tui::state::AppState;
 
 /// Dialog dimensions.
 const DIALOG_WIDTH: u16 = 32;
-const DIALOG_HEIGHT: u16 = 14;
+const DIALOG_HEIGHT: u16 = 15;
 
 /// Compute a centered [`Rect`] of the given size within `area`.
 fn centered_rect(width: u16, height: u16, area: Rect) -> Rect {
@@ -44,7 +44,8 @@ const HELP_TEXT: &str = "\
 \n\
  Global\n\
   q/Q       quit\n\
-  ?         this help";
+  ?         this help\n\
+  c         toggle color";
 
 // ---------------------------------------------------------------------------
 // Rendering

src/tui/run.rs

@@ -146,6 +146,7 @@ fn handle_event(event: Event, state: &mut AppState) {
         }
         match key.code {
             KeyCode::Char('q') => state.should_quit = true,
+            KeyCode::Char('c') => state.color_enabled = !state.color_enabled,
             KeyCode::Esc => state.go_back(),
             _ => {}
         }
@@ -301,4 +302,17 @@ mod tests {
         handle_event(release_event, &mut state);
         assert!(!state.should_quit);
     }
+
+    /// Pressing `c` toggles `color_enabled` off then back on.
+    #[test]
+    fn c_toggles_color_enabled() {
+        // SAFETY: single-threaded test; no other threads reading the env.
+        unsafe { std::env::remove_var("NO_COLOR") };
+        let mut state = AppState::new();
+        assert!(state.color_enabled, "color starts enabled");
+        handle_event(key_press(KeyCode::Char('c')), &mut state);
+        assert!(!state.color_enabled, "color toggled off");
+        handle_event(key_press(KeyCode::Char('c')), &mut state);
+        assert!(state.color_enabled, "color toggled back on");
+    }
 }

src/tui/screens/transcript.rs

@@ -92,7 +92,9 @@ const TOOL_INPUT_TRUNCATE: usize = 120;
 ///
 /// Thinking blocks are skipped.  Tool results are truncated to [`TOOL_RESULT_TRUNCATE`]
 /// chars.  Tool inputs are truncated to [`TOOL_INPUT_TRUNCATE`] chars.
-pub fn build_chat_lines(entries: &[RawEntry]) -> Vec<Line<'static>> {
+///
+/// When `color_enabled` is `false` all spans are rendered without colour styling.
+pub fn build_chat_lines(entries: &[RawEntry], color_enabled: bool) -> Vec<Line<'static>> {
     let mut lines: Vec<Line<'static>> = Vec::new();
 
     for entry in entries {
@@ -101,26 +103,42 @@ pub fn build_chat_lines(entries: &[RawEntry]) -> Vec<Line<'static>> {
         };
         let role = msg.role.as_deref().unwrap_or("?").to_string();
 
+        // Choose a ratatui role label style based on the role name.
+        let role_style = if color_enabled {
+            match role.as_str() {
+                "assistant" => Style::default().fg(Color::Rgb(255, 140, 0)), // orange
+                "user" => Style::default().fg(Color::Rgb(170, 170, 170)),    // grey
+                _ => Style::default(),
+            }
+        } else {
+            Style::default()
+        };
+
         match &msg.content {
             None => {}
             Some(MessageContent::Text(t)) => {
-                let prefix = format!("[{role}]: ");
+                let prefix_label = format!("[{role}]: ");
                 let text = t.clone();
                 // Split on newlines so each source line becomes its own ratatui Line.
                 let mut first = true;
                 for src_line in text.lines() {
-                    let line_text = if first {
+                    if first {
                         first = false;
-                        format!("{prefix}{src_line}")
+                        lines.push(Line::from(vec![
+                            Span::styled(prefix_label.clone(), role_style),
+                            Span::raw(src_line.to_string()),
+                        ]));
                     } else {
                         // Indent continuation lines by the prefix width.
-                        format!("{}{src_line}", " ".repeat(prefix.len()))
-                    };
-                    lines.push(Line::from(line_text));
+                        lines.push(Line::from(format!(
+                            "{}{src_line}",
+                            " ".repeat(prefix_label.len())
+                        )));
+                    }
                 }
                 if first {
                     // Empty text — still emit the prefix.
-                    lines.push(Line::from(prefix));
+                    lines.push(Line::from(Span::styled(prefix_label, role_style)));
                 }
             }
             Some(MessageContent::Blocks(blocks)) => {
@@ -130,19 +148,24 @@ pub fn build_chat_lines(entries: &[RawEntry]) -> Vec<Line<'static>> {
                             // Hidden by default.
                         }
                         ContentBlock::Text { text } => {
-                            let prefix = format!("[{role}]: ");
+                            let prefix_label = format!("[{role}]: ");
                             let mut first = true;
                             for src_line in text.lines() {
-                                let line_text = if first {
+                                if first {
                                     first = false;
-                                    format!("{prefix}{src_line}")
+                                    lines.push(Line::from(vec![
+                                        Span::styled(prefix_label.clone(), role_style),
+                                        Span::raw(src_line.to_string()),
+                                    ]));
                                 } else {
-                                    format!("{}{src_line}", " ".repeat(prefix.len()))
-                                };
-                                lines.push(Line::from(line_text));
+                                    lines.push(Line::from(format!(
+                                        "{}{src_line}",
+                                        " ".repeat(prefix_label.len())
+                                    )));
+                                }
                             }
                             if first {
-                                lines.push(Line::from(prefix));
+                                lines.push(Line::from(Span::styled(prefix_label, role_style)));
                             }
                         }
                         ContentBlock::ToolUse { name, input, .. } => {
@@ -151,9 +174,14 @@ pub fn build_chat_lines(entries: &[RawEntry]) -> Vec<Line<'static>> {
                             let truncated = truncate_str(&input_str, TOOL_INPUT_TRUNCATE);
                             let ellipsis =
                                 if input_str.len() > TOOL_INPUT_TRUNCATE { "…" } else { "" };
+                            let tool_style = if color_enabled {
+                                Style::default().fg(Color::Cyan)
+                            } else {
+                                Style::default()
+                            };
                             lines.push(Line::from(Span::styled(
                                 format!("[tool: {name}] {truncated}{ellipsis}"),
-                                Style::default().fg(Color::Cyan),
+                                tool_style,
                             )));
                         }
                         ContentBlock::ToolResult {
@@ -173,10 +201,14 @@ pub fn build_chat_lines(entries: &[RawEntry]) -> Vec<Line<'static>> {
                             let truncated = truncate_str(&preview, TOOL_RESULT_TRUNCATE);
                             let ellipsis =
                                 if preview.len() > TOOL_RESULT_TRUNCATE { "…" } else { "" };
-                            let style = if is_error.unwrap_or(false) {
+                            let style = if color_enabled {
+                                if is_error.unwrap_or(false) {
                                     Style::default().fg(Color::Red)
                                 } else {
                                     Style::default().fg(Color::Green)
+                                }
+                            } else {
+                                Style::default()
                             };
                             lines.push(Line::from(Span::styled(
                                 format!("[tool_result{err_flag}]: {truncated}{ellipsis}"),
@@ -184,9 +216,14 @@ pub fn build_chat_lines(entries: &[RawEntry]) -> Vec<Line<'static>> {
                             )));
                         }
                         ContentBlock::Image { .. } => {
+                            let img_style = if color_enabled {
+                                Style::default().fg(Color::Yellow)
+                            } else {
+                                Style::default()
+                            };
                             lines.push(Line::from(Span::styled(
                                 "[image]".to_string(),
-                                Style::default().fg(Color::Yellow),
+                                img_style,
                             )));
                         }
                         ContentBlock::Unknown => {
@@ -255,7 +292,7 @@ pub fn render_transcript(f: &mut Frame, area: Rect, state: &AppState) {
         .split(chunks[1]);
 
     // ── Chat log ─────────────────────────────────────────────────────────────
-    let chat_lines = build_chat_lines(&state.transcript_entries);
+    let chat_lines = build_chat_lines(&state.transcript_entries, state.color_enabled);
 
     let chat_border_style = if state.focus == Focus::ChatLog {
         Style::default().fg(Color::Yellow)
@@ -342,7 +379,7 @@ pub fn handle_transcript_event(event: Event, state: &mut AppState) -> bool {
         KeyCode::Tab => {
             state.focus = match state.focus {
                 Focus::ChatLog => Focus::SubagentsPanel,
-                Focus::SubagentsPanel => Focus::ChatLog,
+                Focus::SubagentsPanel | Focus::FilterInput => Focus::ChatLog,
             };
             true
         }
@@ -367,7 +404,7 @@ pub fn handle_transcript_event(event: Event, state: &mut AppState) -> bool {
                 state.subagent_selected = state.subagent_selected.saturating_sub(1);
                 true
             }
-            Focus::ChatLog => {
+            Focus::ChatLog | Focus::FilterInput => {
                 state.transcript_scroll = state.transcript_scroll.saturating_sub(1);
                 true
             }
@@ -381,7 +418,7 @@ pub fn handle_transcript_event(event: Event, state: &mut AppState) -> bool {
                 }
                 true
             }
-            Focus::ChatLog => {
+            Focus::ChatLog | Focus::FilterInput => {
                 state.transcript_scroll = state.transcript_scroll.saturating_add(1);
                 true
             }
@@ -642,14 +679,14 @@ mod tests {
 
     #[test]
     fn chat_lines_empty_entries() {
-        let lines = build_chat_lines(&[]);
+        let lines = build_chat_lines(&[], false);
         assert!(lines.is_empty());
     }
 
     #[test]
     fn chat_lines_user_text() {
         let entry = user_text_entry("Hello, Claude!");
-        let lines = build_chat_lines(&[entry]);
+        let lines = build_chat_lines(&[entry], false);
         assert_eq!(lines.len(), 1);
         let text: String = lines[0].spans.iter().map(|s| s.content.as_ref()).collect();
         assert!(text.contains("[user]: Hello, Claude!"));
@@ -658,7 +695,7 @@ mod tests {
     #[test]
     fn chat_lines_assistant_text() {
         let entry = assistant_text_entry("Here is my answer.");
-        let lines = build_chat_lines(&[entry]);
+        let lines = build_chat_lines(&[entry], false);
         assert_eq!(lines.len(), 1);
         let text: String = lines[0].spans.iter().map(|s| s.content.as_ref()).collect();
         assert!(text.contains("[assistant]: Here is my answer."));
@@ -667,7 +704,7 @@ mod tests {
     #[test]
     fn chat_lines_multiline_text() {
         let entry = user_text_entry("line1\nline2\nline3");
-        let lines = build_chat_lines(&[entry]);
+        let lines = build_chat_lines(&[entry], false);
         assert_eq!(lines.len(), 3);
     }
 
@@ -688,7 +725,7 @@ mod tests {
             model: None,
             stop_reason: None,
         });
-        let lines = build_chat_lines(&[entry]);
+        let lines = build_chat_lines(&[entry], false);
         // Only the Text block should produce a line; Thinking is skipped.
         assert_eq!(lines.len(), 1);
         let text: String = lines[0].spans.iter().map(|s| s.content.as_ref()).collect();
@@ -710,7 +747,7 @@ mod tests {
             model: None,
             stop_reason: None,
         });
-        let lines = build_chat_lines(&[entry]);
+        let lines = build_chat_lines(&[entry], false);
         assert_eq!(lines.len(), 1);
         let text: String = lines[0].spans.iter().map(|s| s.content.as_ref()).collect();
         assert!(text.contains("[tool: Read]"));
@@ -732,7 +769,7 @@ mod tests {
             model: None,
             stop_reason: None,
         });
-        let lines = build_chat_lines(&[entry]);
+        let lines = build_chat_lines(&[entry], false);
         assert_eq!(lines.len(), 1);
         let text: String = lines[0].spans.iter().map(|s| s.content.as_ref()).collect();
         // Should contain the ellipsis marker.
@@ -743,7 +780,7 @@ mod tests {
     fn chat_lines_entries_without_message_skipped() {
         // A "system" entry with no message field should produce no chat lines.
         let entry = make_entry("system");
-        let lines = build_chat_lines(&[entry]);
+        let lines = build_chat_lines(&[entry], false);
         assert!(lines.is_empty());
     }
 

src/tui/state.rs

@@ -74,6 +74,8 @@ pub enum Focus {
     ChatLog,
     /// The sub-agents side panel (shown when sub-agents are present).
     SubagentsPanel,
+    /// The filter input bar at the bottom of the session-list screen.
+    FilterInput,
 }
 
 // ---------------------------------------------------------------------------
@@ -120,6 +122,14 @@ pub struct AppState {
     /// Whether the keyboard-shortcut help overlay is visible.
     pub show_help: bool,
 
+    // ── Display ─────────────────────────────────────────────────────────────
+    /// Whether color coding is enabled in transcript views.
+    ///
+    /// Initialised from the `NO_COLOR` environment variable: `false` when
+    /// `NO_COLOR` is set and non-empty, `true` otherwise.  Can be toggled at
+    /// runtime with the `c` key.
+    pub color_enabled: bool,
+
     // ── Lifecycle ───────────────────────────────────────────────────────────
     /// Set to `true` to signal the event loop to exit.
     pub should_quit: bool,
@@ -132,6 +142,10 @@ impl AppState {
     /// immediately; the caller is responsible for populating [`AppState::sessions`]
     /// before the first frame is drawn.
     pub fn new() -> Self {
+        // Color is on by default; disabled when NO_COLOR is set and non-empty.
+        let color_enabled = std::env::var("NO_COLOR")
+            .map(|v| v.is_empty())
+            .unwrap_or(true);
         Self {
             screen: Screen::SessionList,
             sessions: Vec::new(),
@@ -144,6 +158,7 @@ impl AppState {
             focus: Focus::default(),
             show_quit_dialog: false,
             show_help: false,
+            color_enabled,
             should_quit: false,
         }
     }
@@ -333,4 +348,25 @@ mod tests {
         assert_eq!(cloned.short_id, item.short_id);
         let _ = format!("{item:?}");
     }
+
+    /// `AppState::new()` enables color when `NO_COLOR` is unset.
+    #[test]
+    fn new_color_enabled_when_no_color_unset() {
+        // Remove NO_COLOR from the environment for this test.
+        // SAFETY: single-threaded test; no other threads reading the env.
+        unsafe { std::env::remove_var("NO_COLOR") };
+        let state = AppState::new();
+        assert!(state.color_enabled);
+    }
+
+    /// `AppState::new()` disables color when `NO_COLOR` is set to a non-empty value.
+    #[test]
+    fn new_color_disabled_when_no_color_set() {
+        // SAFETY: single-threaded test; no other threads reading the env.
+        unsafe { std::env::set_var("NO_COLOR", "1") };
+        let state = AppState::new();
+        // Restore the environment before asserting so other tests are unaffected.
+        unsafe { std::env::remove_var("NO_COLOR") };
+        assert!(!state.color_enabled);
+    }
 }