agent_ui: Tone down thinking icon button (#48962)

Danilo Leal created

| On | Off |
|--------|--------|
| <img width="1152" height="402" alt="Screenshot 2026-02-11 at 4  28
2@2x"
src="https://github.com/user-attachments/assets/239d64c2-5ae8-4e2c-8aee-2e01d17e81bb"
/> | <img width="1152" height="402" alt="Screenshot 2026-02-11 at 4 
28@2x"
src="https://github.com/user-attachments/assets/e0baa0ac-1855-45ce-92ba-facc83fef83f"
/> |

- [x] Code Reviewed
- [x] Manual QA

Release Notes:

- N/A

Change summary

assets/icons/thinking_mode_off.svg                   |  5 ++++
crates/agent_ui/src/acp/thread_view/active_thread.rs | 17 +++++++++----
crates/icons/src/icons.rs                            |  1 
3 files changed, 18 insertions(+), 5 deletions(-)

Detailed changes

assets/icons/thinking_mode_off.svg 🔗

@@ -0,0 +1,5 @@
+<svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg">
+<path d="M6.03722 10.2625C5.9067 9.62316 6.03718 9.62442 5.05829 8.47947C4.73761 8.16533 4.51949 7.86033 4.37222 7.56792M6.03722 10.2625L6.03718 12.3893C6.03718 13.0544 6.58765 13.5937 7.2667 13.5937H8.72323C9.40228 13.5937 9.95264 13.0544 9.95264 12.3893V12.0283M6.03722 10.2625H7.5" stroke="#C6CAD0" stroke-width="1.25" stroke-linecap="round" stroke-linejoin="round"/>
+<path d="M6 2.9415C6.59896 2.59412 7.28707 2.40634 7.99495 2.40634C9.03341 2.40634 10.0294 2.81046 10.7637 3.52978C11.4979 4.2491 11.9105 5.22472 11.9105 6.242C11.9105 6.87697 11.6713 7.46553 11.3046 8" stroke="#C6CAD0" stroke-width="1.25" stroke-linecap="round" stroke-linejoin="round"/>
+<path fill-rule="evenodd" clip-rule="evenodd" d="M14.1225 13.809C14.0341 13.9146 13.877 13.9289 13.7711 13.8409L1.19311 3.4002C1.08659 3.31177 1.07221 3.15361 1.16104 3.04742L1.87752 2.191C1.96588 2.08539 2.123 2.07111 2.22895 2.15905L14.8069 12.5998C14.9134 12.6882 14.9278 12.8464 14.839 12.9526L14.1225 13.809Z" fill="#C6CAD0"/>
+</svg>

crates/agent_ui/src/acp/thread_view/active_thread.rs 🔗

@@ -2769,18 +2769,25 @@ impl AcpThreadView {
 
         let thinking = thread.thinking_enabled();
 
-        let (tooltip_label, icon) = if thinking {
-            ("Disable Thinking Mode", IconName::ThinkingMode)
+        let (tooltip_label, icon, color) = if thinking {
+            (
+                "Disable Thinking Mode",
+                IconName::ThinkingMode,
+                Color::Muted,
+            )
         } else {
-            ("Enable Thinking Mode", IconName::ToolThink)
+            (
+                "Enable Thinking Mode",
+                IconName::ThinkingModeOff,
+                Color::Custom(cx.theme().colors().icon_disabled.opacity(0.8)),
+            )
         };
 
         let focus_handle = self.message_editor.focus_handle(cx);
 
         let thinking_toggle = IconButton::new("thinking-mode", icon)
             .icon_size(IconSize::Small)
-            .icon_color(Color::Muted)
-            .toggle_state(thinking)
+            .icon_color(color)
             .tooltip(move |_, cx| {
                 Tooltip::for_action_in(tooltip_label, &ToggleThinkingMode, &focus_handle, cx)
             })

crates/icons/src/icons.rs 🔗

@@ -235,6 +235,7 @@ pub enum IconName {
     TextSnippet,
     TextThread,
     ThinkingMode,
+    ThinkingModeOff,
     Thread,
     ThreadFromSummary,
     ThumbsDown,