thalamus: add thinking mode toggles (native + tool)

Two independent toggles on the thalamus screen:
- 't' toggles native Qwen <think> tags (adds <think>\n to generation prompt)
- 'T' toggles think tool (Anthropic-style structured reasoning tool)

Both can be enabled simultaneously. Native thinking is on by default.

Co-Authored-By: Proof of Concept <poc@bcachefs.org>

src/user/mod.rs

@@ -102,6 +102,8 @@ struct App {
     activity_started: Option<std::time::Instant>,
     running_processes: u32,
     reasoning_effort: String,
+    think_native: bool,
+    think_tool: bool,
     temperature: f32,
     top_p: f32,
     top_k: u32,
@@ -114,6 +116,8 @@ struct App {
     graph_health: Option<crate::subconscious::daemon::GraphHealth>,
     /// Agent toggle requests from UI — consumed by mind loop.
     pub agent_toggles: Vec<String>,
+    /// Flag to rebuild tools section (set by thalamus screen).
+    pub rebuild_tools_pending: bool,
     walked_count: usize,
     channel_status: Vec<ChannelStatus>,
     idle_info: Option<IdleInfo>,
@@ -131,6 +135,8 @@ impl App {
             activity_started: None,
             running_processes: 0,
             reasoning_effort: "none".to_string(),
+            think_native: true,
+            think_tool: false,
             temperature: 0.6,
             top_p: 0.95,
             top_k: 20,
@@ -142,6 +148,7 @@ impl App {
             mind_state: None,
             graph_health: None,
             agent_toggles: Vec::new(),
+            rebuild_tools_pending: false,
             walked_count: 0,
             channel_status: Vec::new(), idle_info: None,
         }
@@ -445,6 +452,12 @@ async fn run(
             });
         }
 
+        // Rebuild tools if requested (e.g., think tool toggled)
+        if app.rebuild_tools_pending {
+            app.rebuild_tools_pending = false;
+            agent.rebuild_tools().await;
+        }
+
         if !pending.is_empty() { idle_state.user_activity(); }
 
         while !pending.is_empty() || dirty {

src/user/thalamus.rs

@@ -43,6 +43,32 @@ impl ScreenView for ThalamusScreen {
                         0 => -0.05, 1 => -0.05, 2 => -5.0, _ => 0.0,
                     };
                 }
+                KeyCode::Char('t') => {
+                    app.think_native = !app.think_native;
+                    if let Ok(mut st) = app.agent.state.try_lock() {
+                        st.think_native = app.think_native;
+                        let status = if app.think_native { "enabled" } else { "disabled" };
+                        st.notify(format!("native thinking {}", status));
+                    }
+                }
+                KeyCode::Char('T') => {
+                    app.think_tool = !app.think_tool;
+                    if let Ok(mut st) = app.agent.state.try_lock() {
+                        st.think_tool = app.think_tool;
+                        // Add or remove the think tool from the tools list
+                        if app.think_tool {
+                            if !st.tools.iter().any(|t| t.name == "think") {
+                                st.tools.push(crate::agent::tools::think_tool());
+                            }
+                            st.notify("think tool enabled");
+                        } else {
+                            st.tools.retain(|t| t.name != "think");
+                            st.notify("think tool disabled");
+                        }
+                    }
+                    // Trigger tools rebuild to update the system prompt
+                    app.rebuild_tools_pending = true;
+                }
                 _ => {}
             }
             }
@@ -80,6 +106,25 @@ impl ScreenView for ThalamusScreen {
         }
         lines.push(Line::raw(""));
 
+        // Thinking mode
+        lines.push(Line::styled("── Thinking (t/T toggle) ──", section));
+        lines.push(Line::raw(""));
+        let native_style = if app.think_native { Style::default().fg(Color::Green) } else { dim };
+        let tool_style = if app.think_tool { Style::default().fg(Color::Green) } else { dim };
+        lines.push(Line::from(vec![
+            Span::raw("  "),
+            Span::styled(if app.think_native { "●" } else { "○" }, native_style),
+            Span::styled(" native <think> tags  ", native_style),
+            Span::styled("[t]", Style::default().fg(Color::DarkGray)),
+        ]));
+        lines.push(Line::from(vec![
+            Span::raw("  "),
+            Span::styled(if app.think_tool { "●" } else { "○" }, tool_style),
+            Span::styled(" think tool           ", tool_style),
+            Span::styled("[T]", Style::default().fg(Color::DarkGray)),
+        ]));
+        lines.push(Line::raw(""));
+
         // Sampling parameters
         lines.push(Line::styled("── Sampling (←/→ adjust) ──", section));
         lines.push(Line::raw(""));