feat(llm): add profile failover and pool health

server/engine_llm_calls_test.go

@@ -0,0 +1,43 @@
+package server
+
+import (
+	"sync"
+	"testing"
+)
+
+func TestEngineActiveLLMCallsConcurrent(t *testing.T) {
+	e := NewEngine(nil)
+	const taskID = "42"
+	const calls = 64
+
+	var started sync.WaitGroup
+	var release sync.WaitGroup
+	var finished sync.WaitGroup
+	started.Add(calls)
+	finished.Add(calls)
+	release.Add(1)
+	for range calls {
+		go func() {
+			defer finished.Done()
+			e.BeginLLMCall(taskID)
+			started.Done()
+			release.Wait()
+			e.EndLLMCall(taskID)
+		}()
+	}
+	started.Wait()
+	if got := e.ActiveLLMCalls(taskID); got != calls {
+		t.Fatalf("active calls = %d, want %d", got, calls)
+	}
+	release.Done()
+	finished.Wait()
+	if got := e.ActiveLLMCalls(taskID); got != 0 {
+		t.Fatalf("active calls after completion = %d, want 0", got)
+	}
+
+	// A defensive extra end must never expose a negative UI count.
+	e.EndLLMCall(taskID)
+	if got := e.ActiveLLMCalls(taskID); got != 0 {
+		t.Fatalf("active calls after extra end = %d, want 0", got)
+	}
+}