feat(agent): add FreeRide provenance marker 🦞 to responses

pkg/agent/loop.go

@@ -1776,10 +1776,14 @@ func (al *AgentLoop) runAgentLoop(
 	}
 
 	if opts.SendResponse && result.finalContent != "" {
+		finalContent := result.finalContent
+		if usedFallback, fallbackModel := ts.GetFallbackInfo(); usedFallback {
+			finalContent += fmt.Sprintf("\n\n🦞 _(FreeRide: %s)_", fallbackModel)
+		}
 		al.bus.PublishOutbound(ctx, bus.OutboundMessage{
 			Channel: opts.Channel,
 			ChatID:  opts.ChatID,
-			Content: result.finalContent,
+			Content: finalContent,
 		})
 	}
 
@@ -2221,6 +2225,7 @@ turnLoop:
 							fbResult.Provider, fbResult.Model, len(fbResult.Attempts)+1),
 						map[string]any{"agent_id": ts.agent.ID, "iteration": iteration},
 					)
+					ts.SetFallbackInfo(true, fbResult.Model)
 				}
 				return fbResult.Response, nil
 			}

pkg/agent/turn.go

@@ -103,6 +103,8 @@ type turnState struct {
 	tokenBudget      *atomic.Int64        // Shared token budget counter
 	lastFinishReason string               // Last LLM finish_reason
 	lastUsage        *providers.UsageInfo // Last LLM usage info
+	usedFallback     bool                 // Whether a fallback/FreeRide model was used
+	fallbackModel    string               // The name of the fallback model used
 
 	// Back-reference to the owning AgentLoop (set for SubTurns only, used for hard abort cascade)
 	al *AgentLoop
@@ -478,6 +480,21 @@ func (ts *turnState) SetLastUsage(usage *providers.UsageInfo) {
 	ts.lastUsage = usage
 }
 
+// SetFallbackInfo sets fallback model info
+func (ts *turnState) SetFallbackInfo(used bool, model string) {
+	ts.mu.Lock()
+	defer ts.mu.Unlock()
+	ts.usedFallback = used
+	ts.fallbackModel = model
+}
+
+// GetFallbackInfo returns fallback model info
+func (ts *turnState) GetFallbackInfo() (bool, string) {
+	ts.mu.RLock()
+	defer ts.mu.RUnlock()
+	return ts.usedFallback, ts.fallbackModel
+}
+
 // Context helper functions for SubTurn
 
 type turnStateKeyType struct{}