Store one prompt definition per ID

prepared_observation_contract_test.go

@@ -137,11 +137,12 @@ func TestPreparedObservationFinishesAfterCredentialAndCapacityFailures(t *testin
 			"profiles": map[string]any{"profile": map[string]any{
 				"endpoint": "https://example.invalid/v1", "model": "model", "api_key_required": true,
 			}},
-			"prompts": map[string]any{"prepared": map[string]any{"1": map[string]any{
+			"prompts": map[string]any{"prepared": map[string]any{
+				"version":         "1",
 				"default_profile": "profile",
 				"messages":        []any{map[string]any{"role": "user", "content": "hello"}},
 				"output":          map[string]any{"format": "text", "validation_mode": "none"},
-			}}},
+			}},
 		}),
 	}}}, promptkit.WithLLMClient(&fakeLLMClient{response: &promptkit.GenerateResponse{Content: "ok"}}))
 	if err != nil {