agent stats: track tool calls by type with EWMA, add Stats pane

- RunStats now includes tool_calls_by_type HashMap
- AutoAgent tracks runs, last_stats, and EWMA for tool calls/failures
- Removed duplicate stats fields from individual agent structs
- Fixed provenance to use bare agent name (no "agent:" prefix)
- Subconscious screen now displays both agent types consistently
- Added Stats pane showing tool call breakdown sorted by count

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

src/agent/oneshot.rs

@@ -22,10 +22,11 @@ use super::Agent;
 // Agent logging — shared by Mind and CLI paths
 // ---------------------------------------------------------------------------
 
-#[derive(Clone, serde::Serialize)]
+#[derive(Clone, Default, serde::Serialize)]
 pub struct RunStats {
     pub messages: usize,
     pub tool_calls: usize,
+    pub tool_failures: usize,
     pub tool_calls_by_type: HashMap<String, usize>,
 }
 
@@ -57,6 +58,7 @@ fn compute_run_stats(conversation: &[super::context::AstNode]) -> RunStats {
 
     let mut messages = 0usize;
     let mut tool_calls = 0usize;
+    let mut tool_failures = 0usize;
     let mut by_type: HashMap<String, usize> = HashMap::new();
 
     for node in conversation {
@@ -64,16 +66,27 @@ fn compute_run_stats(conversation: &[super::context::AstNode]) -> RunStats {
             messages += 1;
             for child in children {
                 if let AstNode::Leaf(leaf) = child {
-                    if let NodeBody::ToolCall { name, .. } = leaf.body() {
-                        tool_calls += 1;
-                        *by_type.entry(name.to_string()).or_default() += 1;
+                    match leaf.body() {
+                        NodeBody::ToolCall { name, .. } => {
+                            tool_calls += 1;
+                            *by_type.entry(name.to_string()).or_default() += 1;
+                        }
+                        NodeBody::ToolResult(text) => {
+                            // Detect failures from error patterns in result
+                            let t = text.trim_start();
+                            if t.starts_with("Error") || t.starts_with("error:") ||
+                               t.starts_with("Failed") || t.contains("not found") {
+                                tool_failures += 1;
+                            }
+                        }
+                        _ => {}
                     }
                 }
             }
         }
     }
 
-    RunStats { messages, tool_calls, tool_calls_by_type: by_type }
+    RunStats { messages, tool_calls, tool_failures, tool_calls_by_type: by_type }
 }
 
 // ---------------------------------------------------------------------------
@@ -96,6 +109,11 @@ pub struct AutoAgent {
     pub current_phase: String,
     pub turn: usize,
     pub enabled: bool,
+    // Stats tracking
+    pub runs: usize,
+    pub last_stats: Option<RunStats>,
+    pub tool_calls_ewma: f64,
+    pub tool_failures_ewma: f64,
 }
 
 /// Per-run conversation backend — wraps a forked agent.
@@ -168,6 +186,10 @@ impl AutoAgent {
             current_phase: String::new(),
             turn: 0,
             enabled: true,
+            runs: 0,
+            last_stats: None,
+            tool_calls_ewma: 0.0,
+            tool_failures_ewma: 0.0,
         }
     }
 
@@ -242,6 +264,17 @@ impl AutoAgent {
         result
     }
 
+    /// Update stats after a run completes. Called with the stats from save_agent_log.
+    pub fn update_stats(&mut self, stats: RunStats) {
+        const ALPHA: f64 = 0.3;
+        self.runs += 1;
+        self.tool_calls_ewma = ALPHA * (stats.tool_calls as f64)
+            + (1.0 - ALPHA) * self.tool_calls_ewma;
+        self.tool_failures_ewma = ALPHA * (stats.tool_failures as f64)
+            + (1.0 - ALPHA) * self.tool_failures_ewma;
+        self.last_stats = Some(stats);
+    }
+
     async fn run_with_backend(
         &mut self,
         backend: &mut Backend,