feat(tui): reasoning cells get dashed rail, italic body, warm tint

Sub-area #2 of the v0.6.6 UI redesign (issue #121). Reasoning is the only deliberately-warm element in the redesigned transcript. The treatment makes that visible: - Header opener becomes `…` (slow exhale) instead of the spinner glyph - Body left rail switches from solid `▏` to dashed `╎` so it visibly differs from message body and tool output rails - Body text carries an italic modifier - Body lines tint with `palette::reasoning_surface_tint(depth)` — 12% blend of SURFACE_REASONING (#362C1A) over DEEPSEEK_INK. ANSI-16 terminals get no bg (the named-color mapping would distort the warm) - A trailing `▎` cursor in ACCENT_REASONING_LIVE follows the most recent body line during streaming, suppressed under low_motion Wires up palette helpers from the prior commit: `ColorDepth::detect`, `reasoning_surface_tint`, `blend`. SURFACE_REASONING is no longer dead-coded. The unused `thinking_symbol` helper is removed since the new header doesn't spin. Tests: dashed rail and italic body land on every body line; streaming cursor appears only when motion is allowed; collapsed-summary affordance keeps working. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-04-27 20:52:59 -05:00
parent 5b7ff8cb69
commit 2b0e73a4cf
2 changed files with 137 additions and 27 deletions
@@ -71,7 +71,6 @@ pub const STATUS_NEUTRAL: Color = Color::Rgb(160, 160, 160); // #A0A0A0
 pub const SURFACE_PANEL: Color = Color::Rgb(21, 33, 52); // #152134
 #[allow(dead_code)]
 pub const SURFACE_ELEVATED: Color = Color::Rgb(28, 42, 64); // #1C2A40
-#[allow(dead_code)]
 pub const SURFACE_REASONING: Color = Color::Rgb(54, 44, 26); // #362C1A
 #[allow(dead_code)]
 pub const SURFACE_REASONING_ACTIVE: Color = Color::Rgb(68, 53, 28); // #44351C
@@ -136,7 +135,6 @@ pub enum ColorDepth {

 impl ColorDepth {
    /// Detect the active terminal's color depth. Honors `COLORTERM`
-    #[allow(dead_code)]
    /// (truecolor / 24bit) first, then falls back to `TERM`. Defaults to
    /// `TrueColor` because most modern terminals support it; the conservative
    /// fallback is `Ansi16` so background tints disappear safely.
@@ -191,7 +189,6 @@ pub fn adapt_bg(color: Color, depth: ColorDepth) -> Color {
 }

 /// Mix two RGB colors at `alpha` (0.0 = `bg`, 1.0 = `fg`). Anything that's not
-#[allow(dead_code)]
 /// RGB falls back to `fg` — there's no meaningful alpha blend on a named
 /// palette entry.
 #[must_use]
@@ -211,7 +208,6 @@ pub fn blend(fg: Color, bg: Color, alpha: f32) -> Color {
 }

 /// Return the reasoning surface color tinted at 12% over the app background.
-#[allow(dead_code)]
 /// This is the headline reasoning treatment in v0.6.6; a 12% blend keeps the
 /// warm bias subtle without competing with body text. Returns `None` when the
 /// terminal can't render the bg faithfully.
@@ -33,6 +33,15 @@ const USER_GLYPH: &str = "\u{258E}"; // ▎
 /// Visual marker for the assistant role. Solid bullet that pulses at 2s
 /// cycle while the response is streaming, holds full brightness when idle.
 const ASSISTANT_GLYPH: &str = "\u{25CF}"; // ●
+/// Reasoning header opener. Replaces the spinner glyph on thinking cells —
+/// reasoning is a slow exhale, not a tool spin.
+const REASONING_OPENER: &str = "\u{2026}"; // …
+/// Reasoning body left rail. Dashed (`╎`) instead of the solid `▏` block to
+/// visually separate reasoning from message body and tool output.
+const REASONING_RAIL: &str = "\u{254E} "; // ╎ + space
+/// Trailing-line cursor on streaming reasoning. Anchored to the live colour
+/// so the user sees where new tokens land.
+const REASONING_CURSOR: &str = "\u{258E}"; // ▎
 const TOOL_CARD_SUMMARY_LINES: usize = 4;
 const THINKING_SUMMARY_LINE_LIMIT: usize = 4;
 const TOOL_DONE_SYMBOL: &str = "•";
@@ -1316,10 +1325,22 @@ fn render_thinking(
 ) -> Vec<Line<'static>> {
    let state = thinking_visual_state(streaming, duration_secs);
    let style = thinking_style();
+    // 12% reasoning surface tint over the app ink — the only deliberately
+    // warm element in the transcript. Dropped on Ansi-16 terminals where the
+    // tint would distort the named palette.
+    let depth = palette::ColorDepth::detect();
+    let body_bg = palette::reasoning_surface_tint(depth);
+    let body_style = match body_bg {
+        Some(bg) => style.italic().bg(bg),
+        None => style.italic(),
+    };
    let mut lines = Vec::new();
+
+    // Header: `…` opener (replaces the spinner; reasoning isn't a tool, it's
+    // a slow exhale) followed by the `thinking` label and live status.
    let mut header_spans = vec![
        Span::styled(
-            format!("{} ", thinking_symbol(state, low_motion)),
+            format!("{REASONING_OPENER} "),
            Style::default().fg(thinking_state_accent(state)),
        ),
        Span::styled("thinking", thinking_title_style()),
@@ -1341,32 +1362,49 @@ fn render_thinking(
    } else {
        content.to_string()
    };
-    let mut rendered = markdown_render::render_markdown(&body_text, content_width, style);
+    let mut rendered = markdown_render::render_markdown(&body_text, content_width, body_style);
    let mut truncated = false;
    if collapsed && rendered.len() > THINKING_SUMMARY_LINE_LIMIT {
        rendered.truncate(THINKING_SUMMARY_LINE_LIMIT);
        truncated = true;
    }

+    let rail_style = Style::default().fg(thinking_state_accent(state));
+    let cursor_style = Style::default().fg(palette::ACCENT_REASONING_LIVE);
+
    if rendered.is_empty() && streaming {
-        lines.push(Line::from(vec![
-            Span::styled("▏ ", Style::default().fg(thinking_state_accent(state))),
-            Span::styled("reasoning in progress...", style.italic()),
-        ]));
+        let mut spans = vec![Span::styled(REASONING_RAIL.to_string(), rail_style)];
+        spans.push(Span::styled(
+            "reasoning in progress...",
+            body_style.italic(),
+        ));
+        if !low_motion {
+            spans.push(Span::styled(
+                format!(" {REASONING_CURSOR}"),
+                cursor_style,
+            ));
+        }
+        lines.push(Line::from(spans));
    }

-    for line in rendered {
-        let mut spans = vec![Span::styled(
-            "▏ ",
-            Style::default().fg(thinking_state_accent(state)),
-        )];
+    let last_idx = rendered.len().saturating_sub(1);
+    for (idx, line) in rendered.into_iter().enumerate() {
+        let mut spans = vec![Span::styled(REASONING_RAIL.to_string(), rail_style)];
        spans.extend(line.spans);
+        // Trailing cursor on the very last body line while streaming —
+        // signals "still generating" without churning every line.
+        if streaming && !low_motion && idx == last_idx {
+            spans.push(Span::styled(
+                format!(" {REASONING_CURSOR}"),
+                cursor_style,
+            ));
+        }
        lines.push(Line::from(spans));
    }

    if collapsed && (!streaming && (truncated || body_text.trim() != content.trim())) {
        lines.push(Line::from(vec![
-            Span::styled("▏ ", Style::default().fg(thinking_state_accent(state))),
+            Span::styled(REASONING_RAIL.to_string(), rail_style),
            Span::styled(
                "thinking collapsed; press Ctrl+O for full text",
                Style::default().fg(palette::TEXT_MUTED).italic(),
@@ -1835,14 +1873,6 @@ fn thinking_status_label(state: ThinkingVisualState) -> &'static str {
    }
 }

-fn thinking_symbol(state: ThinkingVisualState, low_motion: bool) -> String {
-    match state {
-        ThinkingVisualState::Live => status_symbol(None, ToolStatus::Running, low_motion),
-        ThinkingVisualState::Done => "◦".to_string(),
-        ThinkingVisualState::Idle => "·".to_string(),
-    }
-}
-
 fn thinking_title_style() -> Style {
    Style::default()
        .fg(palette::TEXT_SOFT)
@@ -1873,9 +1903,10 @@ fn thinking_state_accent(state: ThinkingVisualState) -> Color {
 mod tests {
    use super::{
        ASSISTANT_GLYPH, ExecCell, ExecSource, GenericToolCell, HistoryCell, PlanStep,
-        PlanUpdateCell, TOOL_RUNNING_SYMBOLS, TOOL_STATUS_SYMBOL_MS, ToolCell, ToolStatus,
-        TranscriptRenderOptions, USER_GLYPH, assistant_label_style_for, extract_reasoning_summary,
-        render_thinking, running_status_label_with_elapsed,
+        PlanUpdateCell, REASONING_CURSOR, REASONING_OPENER, REASONING_RAIL, TOOL_RUNNING_SYMBOLS,
+        TOOL_STATUS_SYMBOL_MS, ToolCell, ToolStatus, TranscriptRenderOptions, USER_GLYPH,
+        assistant_label_style_for, extract_reasoning_summary, render_thinking,
+        running_status_label_with_elapsed,
    };
    use crate::palette;
    use crate::deepseek_theme::Theme;
@@ -2054,6 +2085,89 @@ mod tests {
        );
    }

+    // === Reasoning treatment tests (v0.6.6 UI redesign) ===
+
+    #[test]
+    fn render_thinking_uses_dotted_opener_in_header() {
+        let lines = render_thinking("Step one\nStep two", 80, false, Some(2.0), false, true);
+        let header = &lines[0];
+        // First span carries `…` followed by a space.
+        assert!(
+            header.spans[0].content.starts_with(REASONING_OPENER),
+            "header opener: {:?}",
+            header.spans[0].content
+        );
+    }
+
+    #[test]
+    fn render_thinking_body_lines_use_dashed_rail_and_italic() {
+        let lines = render_thinking(
+            "concrete reasoning content",
+            80,
+            /*streaming*/ false,
+            Some(1.0),
+            /*collapsed*/ false,
+            /*low_motion*/ true,
+        );
+        // Header is index 0; first body line is index 1.
+        assert!(lines.len() >= 2, "expected at least one body line");
+        let body = &lines[1];
+        assert_eq!(
+            body.spans[0].content.as_ref(),
+            REASONING_RAIL,
+            "body rail must be the dashed `╎ ` glyph"
+        );
+        // The body span should carry italic.
+        let italic_seen = body
+            .spans
+            .iter()
+            .skip(1)
+            .any(|span| span.style.add_modifier.contains(Modifier::ITALIC));
+        assert!(italic_seen, "body content should carry italic modifier");
+    }
+
+    #[test]
+    fn render_thinking_streaming_appends_cursor_when_motion_allowed() {
+        let lines = render_thinking(
+            "ongoing reasoning...",
+            80,
+            /*streaming*/ true,
+            None,
+            /*collapsed*/ false,
+            /*low_motion*/ false,
+        );
+        // Last line is the most recent body line — cursor lives there.
+        let last = lines.last().expect("body line present");
+        let last_span = last.spans.last().expect("trailing span present");
+        assert!(
+            last_span.content.contains(REASONING_CURSOR),
+            "expected trailing cursor `▎` on last streaming body line, got {:?}",
+            last_span.content
+        );
+    }
+
+    #[test]
+    fn render_thinking_streaming_omits_cursor_when_low_motion() {
+        let lines = render_thinking(
+            "ongoing reasoning...",
+            80,
+            /*streaming*/ true,
+            None,
+            /*collapsed*/ false,
+            /*low_motion*/ true,
+        );
+        let last = lines.last().expect("body line present");
+        let visible: String = last
+            .spans
+            .iter()
+            .map(|s| s.content.as_ref())
+            .collect::<String>();
+        assert!(
+            !visible.contains(REASONING_CURSOR),
+            "low_motion must suppress the streaming cursor: {visible:?}"
+        );
+    }
+
    // === Theme parity tests ===
    //
    // These lock the visible color/style choices for one plan cell and one