Serialize tool deltas through runtime events

Why: wrapper-side tool deltas raced with serialized run events and could disappear under load.

Evidence: TestToolCallDeltaBeforeExecution race reproduced on the old path, then passed ten race runs with Agent-Native e86e74b; full Backend vet and tests pass.

Impact: one owner emits conversation events; Backend pins the Agent-Native event identity contract.

Refs: Agent-Native PR #46; internal/runtime/llm_direct.go

internal/runtime/llm_direct.go

@@ -233,9 +233,6 @@ func (l *LLMRunner) runDirect(rc RunCtx, stream agentllm.StreamFunc, model strin
 		go func() {
 			defer close(out)
 			for ev := range in {
-				if ev.Kind == agentllm.KindToolCallDelta {
-					st.noteToolDelta(ev)
-				}
 				if ev.Kind == agentllm.KindMessageEnd {
 					if ev.Message.Role == "" {
 						ev.Message.Role = agentllm.RoleAssistant
@@ -488,13 +485,13 @@ func (st *directRun) noteModelSwitch(from, to string) {
 	st.switches = append(st.switches, fmt.Sprintf("模型 %s 在输出前失败，已改用 %s", from, to))
 }
 
-func (st *directRun) noteToolDelta(ev agentllm.Event) {
+func (st *directRun) noteToolDelta(ev nruntime.Event) {
 	if !st.acting {
 		_ = st.rc.Emit(core.EvRunPhase, core.RunPhasePayload{Phase: core.PhaseActing})
 		st.acting = true
 	}
 	_ = st.rc.Emit(core.EvToolCallDelta, core.ToolCallDeltaPayload{
-		Index: ev.ToolIndex, CallID: ev.ToolID, Name: ev.ToolName, Delta: ev.ArgumentsDelta,
+		Index: ev.ToolIndex, CallID: ev.CallID, Name: ev.Tool, Delta: ev.Detail,
 	})
 }
 
@@ -511,6 +508,8 @@ func (st *directRun) onEvent(ev nruntime.Event) {
 		st.thinkStart, st.thinkEnd = time.Time{}, time.Time{}
 		st.textStart, st.textEnd = time.Time{}, time.Time{}
 		st.turnBody = ""
+	case "tool_call_delta":
+		st.noteToolDelta(ev)
 	case "text_delta":
 		if !st.responding {
 			_ = st.rc.Emit(core.EvRunPhase, core.RunPhasePayload{Phase: core.PhaseResponding})