feat(loop): Top5#4 工具循环增强（对齐 OpenClaw agent-loop）——重复检测/并行串行/钩子/errorKind/repair

- 重复调用安全网（critical-tool-loop）：指纹=name+canonical JSON(args)；批内重复第二次跳过回喂
  「duplicate call」；跨轮关键重复(同指纹重现)→首次 block+criticalSeen，再次连续重复→终止整轮
  StopReasonToolLoopTerminated（替代裸 8 轮针对同调用的硬截止）。
- 并行/串行混合：invokeParallel 默认并行，信号量(ToolParallelism 默认4)限并发，结果按调用索引
  写回按原序渲染；串行触发=Options.ToolExecution:sequential 或 SetToolExecutionMode(name,sequential)
  （对齐 OpenClaw「一个 sequential 标记→整组串行」）；goroutine 不泄漏、ctx 取消快速返回。
- 工具钩子：ToolLoopHooks(BatchAdmit/CallAdmit/AfterCall/AfterOutcome) 经 Options.Hooks 注入，
  均 nil-tolerant；供后续敏感操作代审复用（design/11）。terminate 用 every 语义。
- status 分类：ToolError.Kind() 区分 argument-validation(JSON-Schema 失败)/execution；
  失败消息渲染 {kind,message} 让模型区分重发参数 vs 执行失败。
- tool-call-repair：LenientJSONUnmarshal 修 fence 包裹/尾逗号畸形；agent.extractToolCalls 与
  loop.decodeToolCalls 走它；不可修复退化为文本不崩整轮。意图调用未区分回喂提示(后置)。
- tool_execution_update：流式路径 emitToolExecution 发 StreamKindToolExecution(start/end/end:error)。

go build/vet/test 全绿(46包)。TestRun_MaxRounds 改每轮不同参(原同 echo 被安全网拦，预期新行为)。
-race 受宿主 TSan VMA 限制无法运行(与代码无关)。

internal/runtime/agent/step.go

@@ -2,11 +2,11 @@ package agent
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 	"time"
 
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/model"
+	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/tool"
 )
 
 // Stop reasons carried by StepResult.StopReason, consumed by the loop (M2) to
@@ -119,7 +119,11 @@ func extractToolCalls(resp model.Response) ([]ToolCall, bool) {
 	var payload struct {
 		ToolCalls []ToolCall `json:"tool_calls"`
 	}
-	if err := json.Unmarshal([]byte(resp.Content), &payload); err != nil {
+	// Lenient decode repairs common model-emitted malformations (code fences,
+	// trailing commas) so a slightly broken tool-call envelope does not silently
+	// turn into a text answer; an unrecoverable payload still yields ok=false and
+	// the round proceeds as text (the loop never crashes on a bad call).
+	if err := tool.LenientJSONUnmarshal([]byte(resp.Content), &payload); err != nil {
 		return nil, false
 	}
 	if len(payload.ToolCalls) == 0 {

internal/runtime/loop/loop.go

@@ -36,6 +36,15 @@ const (
 	// StopReasonMaxRounds reports that the loop exhausted its round budget
 	// before reaching a final answer.
 	StopReasonMaxRounds = "max_rounds"
+
+	// StopReasonToolLoopTerminated reports that the critical-tool-loop safety net
+	// stopped the run after the same tool call was repeated identically across
+	// consecutive rounds.
+	StopReasonToolLoopTerminated = "tool_loop_terminated"
+
+	// DefaultToolParallelism caps how many tool calls run concurrently when the
+	// loop runs a batch in parallel mode and no explicit cap is configured.
+	DefaultToolParallelism = 4
 )
 
 // Sentinel errors returned by the Loop. Use errors.Is to test for them; they are
@@ -69,19 +78,22 @@ type Result struct {
 // dispatcher, stores, recorder, tracer) are themselves concurrency-safe, which
 // they are by contract. Run keeps all loop state on the stack.
 type Loop struct {
-	agent      *agent.Agent
-	tools      *tool.Dispatcher
-	memory     *memory.Store
-	retriever  *memory.Retriever
-	working    *memory.WorkingMemory
-	extractor  memory.Extractor
-	checkpoint *persist.Store
-	tracer     *trace.Tracer
-	guards     *guardrail.Pipeline
-	personaID  string
-	maxRounds  int
-	onStream   func(model.StreamEvent)
-	log        *slog.Logger
+	agent           *agent.Agent
+	tools           *tool.Dispatcher
+	memory          *memory.Store
+	retriever       *memory.Retriever
+	working         *memory.WorkingMemory
+	extractor       memory.Extractor
+	checkpoint      *persist.Store
+	tracer          *trace.Tracer
+	guards          *guardrail.Pipeline
+	personaID       string
+	maxRounds       int
+	toolExec        string
+	toolParallelism int
+	hooks           ToolLoopHooks
+	onStream        func(model.StreamEvent)
+	log             *slog.Logger
 }
 
 // New builds a Loop from opts, applying defaults. A non-positive MaxRounds
@@ -94,20 +106,31 @@ func New(opts Options) *Loop {
 	if maxRounds <= 0 {
 		maxRounds = DefaultMaxRounds
 	}
+	toolExec := opts.ToolExecution
+	if toolExec == "" {
+		toolExec = toolExecParallel
+	}
+	toolParallelism := opts.ToolParallelism
+	if toolParallelism <= 0 {
+		toolParallelism = DefaultToolParallelism
+	}
 	return &Loop{
-		agent:      opts.Agent,
-		tools:      opts.Tools,
-		memory:     opts.Memory,
-		retriever:  opts.Retriever,
-		working:    opts.WorkingMemory,
-		extractor:  opts.Extractor,
-		checkpoint: opts.Checkpoint,
-		tracer:     opts.Tracer,
-		guards:     opts.Guards,
-		personaID:  opts.PersonaID,
-		maxRounds:  maxRounds,
-		onStream:   opts.OnStream,
-		log:        sourcedLog(opts.Log),
+		agent:           opts.Agent,
+		tools:           opts.Tools,
+		memory:          opts.Memory,
+		retriever:       opts.Retriever,
+		working:         opts.WorkingMemory,
+		extractor:       opts.Extractor,
+		checkpoint:      opts.Checkpoint,
+		tracer:          opts.Tracer,
+		guards:          opts.Guards,
+		personaID:       opts.PersonaID,
+		maxRounds:       maxRounds,
+		toolExec:        toolExec,
+		toolParallelism: toolParallelism,
+		hooks:           opts.Hooks,
+		onStream:        opts.OnStream,
+		log:             sourcedLog(opts.Log),
 	}
 }
 

internal/runtime/loop/loop_extra_test.go

@@ -0,0 +1,330 @@
+package loop
+
+import (
+	"context"
+	"strings"
+	"sync"
+	"testing"
+
+	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/agent"
+	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/model"
+)
+
+func TestRun_DuplicateCallInBatch_Skipped(t *testing.T) {
+	t.Parallel()
+	// Two identical calls in one batch: the second must be skipped, not executed,
+	// and fed back as a duplicate hint.
+	call := `{"tool_calls":[{"name":"echo","args":{"q":"x"}},{"name":"echo","args":{"q":"x"}}]}`
+	ad := &mockAdapter{chat: []mgResp{
+		{resp: model.Response{Content: call}},
+		{resp: model.Response{Content: "done"}},
+	}}
+	td := dispatcherWith(t, &mockTool{name: "echo", result: "hi"})
+	a := newTestAgent(t, ad, td)
+	l := New(Options{Agent: a, MaxRounds: 8})
+
+	res, err := l.Run(context.Background(), "sess", []model.Message{model.TextMessage(model.RoleUser, "go")})
+	if err != nil {
+		t.Fatalf("Run: %v", err)
+	}
+	if res.Text != "done" {
+		t.Fatalf("Text = %q, want done", res.Text)
+	}
+	if res.ToolCallsExecuted != 1 {
+		t.Fatalf("ToolCallsExecuted = %d, want 1 (duplicate skipped)", res.ToolCallsExecuted)
+	}
+	if res.StopReason != agent.StopReasonStop {
+		t.Fatalf("StopReason = %q, want stop", res.StopReason)
+	}
+	last := ad.reqs[len(ad.reqs)-1].Messages
+	// Round 1 appended two tool messages: the executed call result, then the
+	// duplicate skip. The last two messages before the final turn are those.
+	result := last[len(last)-2]
+	skip := last[len(last)-1]
+	if !strings.Contains(result.Content[0].Text, "hi") {
+		t.Fatalf("expected echo result, got %q", result.Content[0].Text)
+	}
+	if !strings.Contains(skip.Content[0].Text, "skipped") || !strings.Contains(skip.Content[0].Text, "duplicate") {
+		t.Fatalf("expected duplicate-skip message, got %q", skip.Content[0].Text)
+	}
+}
+
+func TestRun_CriticalToolLoop_Terminates(t *testing.T) {
+	t.Parallel()
+	// The identical call repeats across rounds: round 2 is blocked (critical
+	// loop flagged), round 3 terminates the run.
+	call := `{"tool_calls":[{"name":"echo","args":{"q":"x"}}]}`
+	ad := &mockAdapter{chat: []mgResp{
+		{resp: model.Response{Content: call}},
+		{resp: model.Response{Content: call}},
+		{resp: model.Response{Content: call}},
+	}}
+	td := dispatcherWith(t, &mockTool{name: "echo", result: "hi"})
+	a := newTestAgent(t, ad, td)
+	l := New(Options{Agent: a, MaxRounds: 8})
+
+	res, err := l.Run(context.Background(), "sess", []model.Message{model.TextMessage(model.RoleUser, "go")})
+	if err != nil {
+		t.Fatalf("Run: %v", err)
+	}
+	if res.StopReason != StopReasonToolLoopTerminated {
+		t.Fatalf("StopReason = %q, want %q", res.StopReason, StopReasonToolLoopTerminated)
+	}
+	if res.ToolCallsExecuted != 1 {
+		t.Fatalf("ToolCallsExecuted = %d, want 1 (only round 1 executed)", res.ToolCallsExecuted)
+	}
+	if res.Steps != 3 {
+		t.Fatalf("Steps = %d, want 3", res.Steps)
+	}
+	if !strings.Contains(res.Text, "critical tool-loop") {
+		t.Fatalf("Text = %q, want critical tool-loop message", res.Text)
+	}
+}
+
+func TestRun_Parallel_ResultsInCallOrder(t *testing.T) {
+	t.Parallel()
+	call := `{"tool_calls":[{"name":"aa","args":{}},{"name":"bb","args":{}},{"name":"cc","args":{}}]}`
+	ad := &mockAdapter{chat: []mgResp{
+		{resp: model.Response{Content: call}},
+		{resp: model.Response{Content: "final"}},
+	}}
+	td := dispatcherWith(t,
+		&mockTool{name: "aa", result: "va"},
+		&mockTool{name: "bb", result: "vb"},
+		&mockTool{name: "cc", result: "vc"},
+	)
+	a := newTestAgent(t, ad, td)
+	l := New(Options{Agent: a, MaxRounds: 8, ToolExecution: "parallel"})
+
+	res, err := l.Run(context.Background(), "sess", []model.Message{model.TextMessage(model.RoleUser, "go")})
+	if err != nil {
+		t.Fatalf("Run: %v", err)
+	}
+	if res.Text != "final" {
+		t.Fatalf("Text = %q, want final", res.Text)
+	}
+	if res.ToolCallsExecuted != 3 {
+		t.Fatalf("ToolCallsExecuted = %d, want 3", res.ToolCallsExecuted)
+	}
+	last := ad.reqs[len(ad.reqs)-1].Messages
+	if len(last) < 4 {
+		t.Fatalf("messages = %d, want at least 4 (user + 3 results)", len(last))
+	}
+	got := make([]string, 3)
+	for i := range got {
+		got[i] = last[len(last)-3+i].Content[0].Text
+	}
+	want := []string{
+		"tool aa result: va",
+		"tool bb result: vb",
+		"tool cc result: vc",
+	}
+	for i := range want {
+		if got[i] != want[i] {
+			t.Fatalf("result %d = %q, want %q (call order must be preserved)", i, got[i], want[i])
+		}
+	}
+}
+
+func TestRun_Sequential_ExecutesAll(t *testing.T) {
+	t.Parallel()
+	call := `{"tool_calls":[{"name":"aa","args":{}},{"name":"bb","args":{}}]}`
+	ad := &mockAdapter{chat: []mgResp{
+		{resp: model.Response{Content: call}},
+		{resp: model.Response{Content: "final"}},
+	}}
+	td := dispatcherWith(t,
+		&mockTool{name: "aa", result: "va"},
+		&mockTool{name: "bb", result: "vb"},
+	)
+	a := newTestAgent(t, ad, td)
+	l := New(Options{Agent: a, MaxRounds: 8, ToolExecution: "sequential"})
+
+	res, err := l.Run(context.Background(), "sess", []model.Message{model.TextMessage(model.RoleUser, "go")})
+	if err != nil {
+		t.Fatalf("Run: %v", err)
+	}
+	if res.ToolCallsExecuted != 2 {
+		t.Fatalf("ToolCallsExecuted = %d, want 2", res.ToolCallsExecuted)
+	}
+}
+
+func TestRun_ArgumentValidation_ErrorKind(t *testing.T) {
+	t.Parallel()
+	// Missing required field -> the fed-back failure carries errorKind
+	// argument-validation so the model can re-issue a corrected call.
+	call := `{"tool_calls":[{"name":"req","args":{}}]}`
+	ad := &mockAdapter{chat: []mgResp{
+		{resp: model.Response{Content: call}},
+		{resp: model.Response{Content: "recovered"}},
+	}}
+	td := dispatcherWith(t, &mockTool{name: "req", params: map[string]any{"required": []any{"must"}}})
+	a := newTestAgent(t, ad, td)
+	l := New(Options{Agent: a, MaxRounds: 8})
+
+	res, err := l.Run(context.Background(), "sess", []model.Message{model.TextMessage(model.RoleUser, "go")})
+	if err != nil {
+		t.Fatalf("Run: %v", err)
+	}
+	if res.Text != "recovered" {
+		t.Fatalf("Text = %q, want recovered", res.Text)
+	}
+	last := ad.reqs[len(ad.reqs)-1].Messages
+	lastMsg := last[len(last)-1]
+	if !strings.Contains(lastMsg.Content[0].Text, `"kind":"argument-validation"`) {
+		t.Fatalf("result should carry argument-validation kind, got %q", lastMsg.Content[0].Text)
+	}
+}
+
+func TestRun_BatchAdmit_BlocksBatch(t *testing.T) {
+	t.Parallel()
+	call := `{"tool_calls":[{"name":"echo","args":{"q":"x"}}]}`
+	ad := &mockAdapter{chat: []mgResp{
+		{resp: model.Response{Content: call}},
+		{resp: model.Response{Content: "after block"}},
+	}}
+	td := dispatcherWith(t, &mockTool{name: "echo", result: "hi"})
+	a := newTestAgent(t, ad, td)
+	l := New(Options{Agent: a, MaxRounds: 8, Hooks: ToolLoopHooks{
+		BatchAdmit: func(ctx context.Context, calls []agent.ToolCall) (bool, string) {
+			return false, "policy denied"
+		},
+	}})
+
+	res, err := l.Run(context.Background(), "sess", []model.Message{model.TextMessage(model.RoleUser, "go")})
+	if err != nil {
+		t.Fatalf("Run: %v", err)
+	}
+	if res.ToolCallsExecuted != 0 {
+		t.Fatalf("ToolCallsExecuted = %d, want 0 (batch blocked)", res.ToolCallsExecuted)
+	}
+	last := ad.reqs[len(ad.reqs)-1].Messages
+	lastMsg := last[len(last)-1]
+	if !strings.Contains(lastMsg.Content[0].Text, "policy denied") {
+		t.Fatalf("expected blocked batch message, got %q", lastMsg.Content[0].Text)
+	}
+}
+
+func TestRun_CallAdmit_VetoesSingleCall(t *testing.T) {
+	t.Parallel()
+	call := `{"tool_calls":[{"name":"echo","args":{"q":"x"}}]}`
+	ad := &mockAdapter{chat: []mgResp{
+		{resp: model.Response{Content: call}},
+		{resp: model.Response{Content: "after veto"}},
+	}}
+	td := dispatcherWith(t, &mockTool{name: "echo", result: "hi"})
+	a := newTestAgent(t, ad, td)
+	l := New(Options{Agent: a, MaxRounds: 8, Hooks: ToolLoopHooks{
+		CallAdmit: func(ctx context.Context, call agent.ToolCall) *ToolCallVeto {
+			if call.Name == "echo" {
+				return &ToolCallVeto{Block: true, Reason: "sensitive action requires approval"}
+			}
+			return nil
+		},
+	}})
+
+	res, err := l.Run(context.Background(), "sess", []model.Message{model.TextMessage(model.RoleUser, "go")})
+	if err != nil {
+		t.Fatalf("Run: %v", err)
+	}
+	if res.ToolCallsExecuted != 0 {
+		t.Fatalf("ToolCallsExecuted = %d, want 0 (call vetoed)", res.ToolCallsExecuted)
+	}
+	last := ad.reqs[len(ad.reqs)-1].Messages
+	lastMsg := last[len(last)-1]
+	if !strings.Contains(lastMsg.Content[0].Text, "sensitive action requires approval") {
+		t.Fatalf("expected veto message, got %q", lastMsg.Content[0].Text)
+	}
+}
+
+func TestRun_AfterCall_RewritesResult(t *testing.T) {
+	t.Parallel()
+	call := `{"tool_calls":[{"name":"echo","args":{"q":"x"}}]}`
+	ad := &mockAdapter{chat: []mgResp{
+		{resp: model.Response{Content: call}},
+		{resp: model.Response{Content: "final"}},
+	}}
+	td := dispatcherWith(t, &mockTool{name: "echo", result: "raw"})
+	a := newTestAgent(t, ad, td)
+	l := New(Options{Agent: a, MaxRounds: 8, Hooks: ToolLoopHooks{
+		AfterCall: func(ctx context.Context, call agent.ToolCall, outcome ToolOutcome) *ToolOutcome {
+			if call.Name == "echo" {
+				outcome.Result = "rewritten"
+				return &outcome
+			}
+			return nil
+		},
+	}})
+
+	if _, err := l.Run(context.Background(), "sess", []model.Message{model.TextMessage(model.RoleUser, "go")}); err != nil {
+		t.Fatalf("Run: %v", err)
+	}
+	last := ad.reqs[len(ad.reqs)-1].Messages
+	lastMsg := last[len(last)-1]
+	if !strings.Contains(lastMsg.Content[0].Text, "rewritten") {
+		t.Fatalf("expected rewritten result, got %q", lastMsg.Content[0].Text)
+	}
+}
+
+func TestRun_ToolCallRepair_FencedJSON(t *testing.T) {
+	t.Parallel()
+	// A code-fenced tool-call envelope is repaired and executed rather than
+	// silently becoming a text answer.
+	call := "```json\n{\"tool_calls\":[{\"name\":\"echo\",\"args\":{\"q\":\"hi\"}}]}\n```"
+	ad := &mockAdapter{chat: []mgResp{
+		{resp: model.Response{Content: call}},
+		{resp: model.Response{Content: "done"}},
+	}}
+	td := dispatcherWith(t, &mockTool{name: "echo", result: "hi"})
+	a := newTestAgent(t, ad, td)
+	l := New(Options{Agent: a, MaxRounds: 8})
+
+	res, err := l.Run(context.Background(), "sess", []model.Message{model.TextMessage(model.RoleUser, "go")})
+	if err != nil {
+		t.Fatalf("Run: %v", err)
+	}
+	if res.ToolCallsExecuted != 1 || res.Text != "done" {
+		t.Fatalf("ToolCallsExecuted = %d, Text = %q; want 1 + done (fenced JSON repaired)", res.ToolCallsExecuted, res.Text)
+	}
+}
+
+func TestRun_StreamToolExecution_EmitsProgress(t *testing.T) {
+	t.Parallel()
+	call := `{"tool_calls":[{"name":"echo","args":{"q":"x"}}]}`
+	ad := &mockAdapter{
+		stream: []mgResp{
+			{resp: model.Response{Content: call}},
+			{resp: model.Response{Content: "done"}},
+		},
+		chunks: [][]string{{"x"}},
+	}
+	td := dispatcherWith(t, &mockTool{name: "echo", result: "hi"})
+	a := newTestAgent(t, ad, td)
+	var mu sync.Mutex
+	var evs []model.StreamEvent
+	l := New(Options{
+		Agent: a,
+		OnStream: func(ev model.StreamEvent) {
+			mu.Lock()
+			evs = append(evs, ev)
+			mu.Unlock()
+		},
+		MaxRounds: 8,
+	})
+
+	if _, err := l.Run(context.Background(), "sess", []model.Message{model.TextMessage(model.RoleUser, "go")}); err != nil {
+		t.Fatalf("Run: %v", err)
+	}
+	mu.Lock()
+	defer mu.Unlock()
+	saw := false
+	for _, ev := range evs {
+		if ev.Kind == model.StreamKindToolExecution {
+			saw = true
+			break
+		}
+	}
+	if !saw {
+		t.Fatalf("expected a tool_execution_update event on the streaming path, got %+v", evs)
+	}
+}

internal/runtime/loop/loop_test.go

@@ -84,10 +84,13 @@ func TestRun_ToolCallThenFinal_FeedsBack(t *testing.T) {
 
 func TestRun_MaxRounds(t *testing.T) {
 	t.Parallel()
-	call := `{"tool_calls":[{"name":"echo","args":{"q":"x"}}]}`
+	// Distinct calls per round so the critical-tool-loop safety net does not
+	// intervene; the goal here is to exercise the round budget.
+	call1 := `{"tool_calls":[{"name":"echo","args":{"q":"x"}}]}`
+	call2 := `{"tool_calls":[{"name":"echo","args":{"q":"y"}}]}`
 	ad := &mockAdapter{chat: []mgResp{
-		{resp: model.Response{Content: call}},
-		{resp: model.Response{Content: call}},
+		{resp: model.Response{Content: call1}},
+		{resp: model.Response{Content: call2}},
 	}}
 	td := dispatcherWith(t, &mockTool{name: "echo", result: "x"})
 	a := newTestAgent(t, ad, td)

internal/runtime/loop/options.go

@@ -52,6 +52,16 @@ type Options struct {
 	// forwarded to this callback (model.StreamEvent), so the frontend can render
 	// body text, tool calls and (eventually) reasoning segments independently.
 	OnStream func(model.StreamEvent)
+	// ToolExecution selects how a batch of tool calls is run: "parallel" (the
+	// default) or "sequential". Empty means parallel.
+	ToolExecution string
+	// ToolParallelism caps how many tool calls run concurrently when ToolExecution
+	// is "parallel". Non-positive selects DefaultToolParallelism (4).
+	ToolParallelism int
+	// Hooks installs optional per-batch/per-call tool-loop hooks. Every field is
+	// nil-tolerant; these are reserved for "敏感操作代审" (design/11) and the
+	// future asynchronous-tool path. A zero Hooks value is a no-op.
+	Hooks ToolLoopHooks
 	// Log is the base logger. Nil is replaced with a discard logger tagged with
 	// source "runtime/loop".
 	Log *slog.Logger

internal/runtime/loop/request.go

@@ -1,10 +1,9 @@
 package loop
 
 import (
-	"encoding/json"
-
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/agent"
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/model"
+	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/tool"
 )
 
 // buildRequest assembles a model.Request from the agent's public surface,
@@ -71,7 +70,11 @@ func decodeToolCalls(resp model.Response) ([]agent.ToolCall, bool) {
 	var payload struct {
 		ToolCalls []agent.ToolCall `json:"tool_calls"`
 	}
-	if err := json.Unmarshal([]byte(resp.Content), &payload); err != nil {
+	// Lenient decode repairs common model-emitted malformations (code fences,
+	// trailing commas) so a slightly broken tool-call envelope does not turn into
+	// a text answer; an unrecoverable payload still yields ok=false and the round
+	// proceeds as text.
+	if err := tool.LenientJSONUnmarshal([]byte(resp.Content), &payload); err != nil {
 		return nil, false
 	}
 	if len(payload.ToolCalls) == 0 {

internal/runtime/loop/run.go

@@ -30,6 +30,7 @@ func (l *Loop) Run(ctx context.Context, sessionID string, messages []model.Messa
 	}
 
 	msgs := l.injectMemory(ctx, messages)
+	toolState := &toolLoopState{prevFP: make(map[string]bool)}
 	res := &Result{}
 	for step := 1; step <= l.maxRounds; step++ {
 		if err := ctx.Err(); err != nil {
@@ -56,14 +57,24 @@ func (l *Loop) Run(ctx context.Context, sessionID string, messages []model.Messa
 			return res, nil
 		}
 
-		newMsgs, executed, err := l.runToolCalls(rc, msgs, outcome.toolCalls)
+		batch, err := l.runToolCalls(rc, msgs, outcome.toolCalls, toolState)
 		if err != nil {
 			return nil, fmt.Errorf("loop: run: step %d: tools: %w", step, err)
 		}
-		msgs = newMsgs
-		res.ToolCallsExecuted += executed
+		msgs = batch.messages
+		res.ToolCallsExecuted += batch.executed
 		l.saveCheckpoint(ctx, sessionID, step, msgs, agent.StopReasonToolCalls)
 		l.extractMemory(ctx, msgs, step)
+
+		// The critical-tool-loop safety net (or a terminating hook) stops the
+		// round without waiting for a real final answer.
+		if batch.terminate {
+			res.Text = criticalToolLoopTerminalReason
+			res.StopReason = StopReasonToolLoopTerminated
+			l.saveCheckpoint(ctx, sessionID, step, msgs, StopReasonToolLoopTerminated)
+			l.extractMemory(ctx, msgs, step)
+			return res, nil
+		}
 	}
 
 	// Budget exhausted without a final answer.

internal/runtime/loop/tools.go

@@ -3,7 +3,9 @@ package loop
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
+	"sync"
 
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/agent"
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/model"
@@ -11,38 +13,378 @@ import (
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/trace"
 )
 
-// runToolCalls executes each requested tool call, appending a RoleTool result
-// message (success or failure) so the model can continue. It returns the updated
-// message slice and the number of tool calls invoked. Invocation is delegated to
-// the dispatched tool, which applies the per-tool deadline; a missing dispatcher
-// is fed back as an error so the loop never panics or crashes on an unhandled
-// call.
-func (l *Loop) runToolCalls(ctx context.Context, messages []model.Message, calls []agent.ToolCall) ([]model.Message, int, error) {
+// ToolExecutionMode tokens accepted by Options.ToolExecution. Empty selects
+// toolExecParallel.
+const (
+	toolExecParallel   = "parallel"
+	toolExecSequential = "sequential"
+)
+
+// criticalToolLoopTerminalReason is surfaced as Result.Text and on every blocked
+// call when the critical-tool-loop safety net stops the run.
+const criticalToolLoopTerminalReason = "critical tool-loop detected: an identical tool call was repeated across rounds; the run is stopping"
+
+// ToolCallVeto is returned by a CallAdmit hook to block a single call.
+type ToolCallVeto struct {
+	Block  bool
+	Reason string
+}
+
+// ToolOutcome is the normalized result of executing one tool call. It is what an
+// after-call / after-outcome hook observes and may rewrite before the loop
+// renders it back to the model.
+type ToolOutcome struct {
+	// Result is the value the tool returned (nil on failure or skip).
+	Result any
+	// Err is non-nil when the call failed to execute; it is nil on success.
+	Err error
+	// ErrKind classifies a failure as tool.KindArgumentValidation or
+	// tool.KindExecution (the task's errorKind status classification). Empty on
+	// success.
+	ErrKind string
+	// Skipped is true when the call never executed (duplicate / blocked / vetoed).
+	Skipped bool
+	// Reason is a human-readable explanation for a skipped call.
+	Reason string
+	// Terminate, when set by a hook, signals that the whole round should stop
+	// once every call in the batch is also marked terminate.
+	Terminate bool
+}
+
+// ToolLoopHooks groups the optional per-batch / per-call tool-loop hooks. Every
+// field is nil-tolerant. These are the extension points the loop keeps open for
+// "敏感操作代审" (design/11 batch admission) and the future async-tool path, so
+// the audit layer and the loop are decoupled.
+type ToolLoopHooks struct {
+	// BatchAdmit is called once per batch before any call executes. Returning
+	// (false, reason) blocks the whole batch: every call becomes a skipped result
+	// carrying reason. nil = always admit.
+	BatchAdmit func(ctx context.Context, calls []agent.ToolCall) (bool, string)
+	// CallAdmit is called per call before it executes. A non-nil veto with
+	// Block=true blocks that single call. nil = always admit.
+	CallAdmit func(ctx context.Context, call agent.ToolCall) *ToolCallVeto
+	// AfterCall rewrites a call's outcome after the tool executes. A nil return
+	// keeps the original. It runs before AfterOutcome.
+	AfterCall func(ctx context.Context, call agent.ToolCall, outcome ToolOutcome) *ToolOutcome
+	// AfterOutcome observes/rewrites the finalized outcome (after AfterCall and
+	// after any skip/block decision) immediately before the result is rendered
+	// back to the model. nil = keep the outcome.
+	AfterOutcome func(ctx context.Context, call agent.ToolCall, outcome ToolOutcome) *ToolOutcome
+}
+
+// toolRunResult is the outcome of running one tool batch.
+type toolRunResult struct {
+	messages  []model.Message
+	executed  int
+	terminate bool
+}
+
+// toolLoopState carries the per-run state of the critical-tool-loop safety net.
+// It is scoped to a single Run call, so concurrent runs never share it.
+type toolLoopState struct {
+	criticalSeen bool            // a critical loop was already reported this run
+	prevFP       map[string]bool // fingerprints seen in the immediately previous batch
+}
+
+// toolCallAction is the execution decision for one call after classification.
+type toolCallAction struct {
+	run    bool   // execute the call
+	reason string // when run==false, the human reason fed back to the model
+}
+
+// runToolCalls executes a batch of model-requested tool calls. It classifies
+// duplicate invocations (the critical-tool-loop safety net), applies the optional
+// batch/per-call hooks, runs the surviving calls in parallel (bounded) or
+// serially, and feeds every outcome back as a RoleTool message in the original
+// call order. It returns the number of calls actually invoked (executed), the
+// updated message slice, and whether the round should terminate.
+//
+// Invocation is delegated to the dispatched tool, which applies the per-tool
+// deadline; a missing dispatcher is fed back as an error so the loop never
+// panics or crashes on an unhandled call.
+func (l *Loop) runToolCalls(ctx context.Context, messages []model.Message, calls []agent.ToolCall, st *toolLoopState) (toolRunResult, error) {
 	d := l.dispatcher()
-	out := messages
-	executed := 0
-	for _, tc := range calls {
-		var (
-			result    any
-			invokeErr error
-		)
-		if d == nil {
-			invokeErr = fmt.Errorf("no tool dispatcher configured for %q", tc.Name)
-		} else {
-			_, toolSpan := l.span(ctx, "tool."+tc.Name, trace.SpanKindTool)
-			result, invokeErr = d.Invoke(ctx, tc.Name, tc.Args)
-			if invokeErr != nil {
-				l.spanProp(toolSpan, "error", invokeErr.Error())
-				l.finishSpan(toolSpan, trace.SpanStatusError)
-			} else {
-				l.spanProp(toolSpan, "result", result)
-				l.finishSpan(toolSpan, trace.SpanStatusOK)
+	res := toolRunResult{messages: messages}
+	if len(calls) == 0 {
+		return res, nil
+	}
+
+	actions, terminate := classifyToolBatch(st, calls)
+	if terminate {
+		res.terminate = true
+	}
+
+	// BatchAdmit hook (audit / political review): block the whole batch.
+	if l.hooks.BatchAdmit != nil {
+		if ok, reason := l.hooks.BatchAdmit(ctx, calls); !ok {
+			if reason == "" {
+				reason = "tool batch blocked by policy"
+			}
+			for i := range calls {
+				actions[i] = toolCallAction{run: false, reason: reason}
 			}
 		}
-		executed++
-		out = append(out, toolResultMessage(tc, result, invokeErr))
 	}
-	return out, executed, nil
+
+	// CallAdmit hook: per-call veto over the calls we intend to run.
+	if l.hooks.CallAdmit != nil {
+		for i := range calls {
+			if !actions[i].run {
+				continue
+			}
+			if veto := l.hooks.CallAdmit(ctx, calls[i]); veto != nil && veto.Block {
+				reason := veto.Reason
+				if reason == "" {
+					reason = "tool call blocked by policy"
+				}
+				actions[i] = toolCallAction{run: false, reason: reason}
+			}
+		}
+	}
+
+	// Decide serial vs parallel: explicit sequential mode, or any call whose tool
+	// is declared sequential (a single sequential marker makes the whole group
+	// serial, matching OpenClaw's launchParallelToolCalls).
+	sequential := l.toolExec == toolExecSequential
+	if !sequential && d != nil {
+		for i := range calls {
+			if actions[i].run && d.IsSequential(calls[i].Name) {
+				sequential = true
+				break
+			}
+		}
+	}
+
+	outcomes := make([]ToolOutcome, len(calls))
+	if sequential {
+		for i := range calls {
+			if actions[i].run {
+				outcomes[i] = l.invokeOne(ctx, d, calls[i])
+				res.executed++
+			} else {
+				outcomes[i] = skippedOutcome(actions[i].reason)
+			}
+		}
+	} else {
+		idxs := make([]int, 0, len(calls))
+		for i := range calls {
+			if actions[i].run {
+				idxs = append(idxs, i)
+			} else {
+				outcomes[i] = skippedOutcome(actions[i].reason)
+			}
+		}
+		l.invokeParallel(ctx, d, calls, idxs, outcomes)
+		res.executed += len(idxs)
+	}
+
+	// AfterCall hook (only for calls that actually executed).
+	if l.hooks.AfterCall != nil {
+		for i := range calls {
+			if outcomes[i].Skipped {
+				continue
+			}
+			if after := l.hooks.AfterCall(ctx, calls[i], outcomes[i]); after != nil {
+				outcomes[i] = *after
+			}
+		}
+	}
+
+	// AfterOutcome hook (runs on every finalized outcome, skipped or not).
+	if l.hooks.AfterOutcome != nil {
+		for i := range calls {
+			if after := l.hooks.AfterOutcome(ctx, calls[i], outcomes[i]); after != nil {
+				outcomes[i] = *after
+			}
+		}
+	}
+
+	// A hook may ask to terminate the round by marking every call terminate
+	// (OpenClaw's shouldTerminateToolBatch).
+	if !res.terminate && shouldTerminateBatch(outcomes) {
+		res.terminate = true
+	}
+
+	// Render results in the original call order so the model sees a stable feed.
+	for i := range calls {
+		res.messages = append(res.messages, toolResultMessage(calls[i], outcomes[i]))
+	}
+	return res, nil
+}
+
+// classifyToolBatch partitions a batch into run/skip decisions, enforcing the
+// critical-tool-loop safety net:
+//
+//   - A call identical (same name + arguments) to one earlier in the same batch
+//     is skipped with a duplicate hint (never executes).
+//   - A call identical to one from a previous round is a critical-loop repeat:
+//     the first occurrence blocks the repeated call and sets criticalSeen, so the
+//     model gets a turn to reassess; a second consecutive occurrence terminates
+//     the whole run.
+//
+// It returns (actions, terminate). When terminate is true every call is blocked
+// with criticalToolLoopTerminalReason and the round must end.
+func classifyToolBatch(st *toolLoopState, calls []agent.ToolCall) ([]toolCallAction, bool) {
+	seen := make(map[string]bool, len(calls))
+	actions := make([]toolCallAction, len(calls))
+	repeat := false
+	for i, call := range calls {
+		fp := toolFingerprint(call)
+		if seen[fp] {
+			// Duplicate of a call already in this batch.
+			if st.prevFP[fp] {
+				actions[i] = toolCallAction{run: false, reason: repeatedCallReason()}
+				repeat = true
+			} else {
+				actions[i] = toolCallAction{run: false, reason: duplicateCallReason()}
+			}
+			continue
+		}
+		seen[fp] = true
+		if st.prevFP[fp] {
+			// Repeated from the previous round — a critical loop.
+			actions[i] = toolCallAction{run: false, reason: repeatedCallReason()}
+			repeat = true
+		} else {
+			actions[i] = toolCallAction{run: true}
+		}
+	}
+
+	// Remember which fingerprints were live this round for the next round's
+	// cross-round repeat detection.
+	st.prevFP = seen
+
+	terminate := false
+	if repeat {
+		if st.criticalSeen {
+			terminate = true
+			for i := range actions {
+				actions[i] = toolCallAction{run: false, reason: criticalToolLoopTerminalReason}
+			}
+		} else {
+			st.criticalSeen = true
+		}
+	}
+	return actions, terminate
+}
+
+// invokeOne executes a single tool call under its per-tool deadline, emitting a
+// tool span, streaming tool_execution_update progress and normalizing the
+// outcome.
+func (l *Loop) invokeOne(ctx context.Context, d *tool.Dispatcher, tc agent.ToolCall) ToolOutcome {
+	if d == nil {
+		return ToolOutcome{Err: fmt.Errorf("no tool dispatcher configured for %q", tc.Name), ErrKind: tool.KindExecution}
+	}
+	l.emitToolExecution(tc.Name, "start")
+	_, toolSpan := l.span(ctx, "tool."+tc.Name, trace.SpanKindTool)
+	result, err := d.Invoke(ctx, tc.Name, tc.Args)
+	phase := "end"
+	if err != nil {
+		phase = "end:error"
+	}
+	l.emitToolExecution(tc.Name, phase)
+	out := ToolOutcome{Result: result, Err: err, ErrKind: errorKind(err)}
+	if err != nil {
+		l.spanProp(toolSpan, "error", err.Error())
+		l.spanProp(toolSpan, "error_kind", out.ErrKind)
+		l.finishSpan(toolSpan, trace.SpanStatusError)
+	} else {
+		l.spanProp(toolSpan, "result", result)
+		l.finishSpan(toolSpan, trace.SpanStatusOK)
+	}
+	return out
+}
+
+// emitToolExecution forwards a tool_execution_update progress event to the
+// frontend when the loop is on the streaming path (OnStream configured); it is a
+// no-op otherwise. phase is a short label like "start" or "end:error".
+func (l *Loop) emitToolExecution(name, phase string) {
+	if l.onStream == nil {
+		return
+	}
+	l.onStream(model.StreamEvent{Kind: model.StreamKindToolExecution, Delta: phase + ":" + name})
+}
+
+// invokeParallel runs calls at idxs concurrently, capped at the loop's
+// parallelism, writing each outcome back into out at its call index so callers
+// can render results in the original order. The semaphore bounds concurrency and
+// in-flight goroutines release their slot on completion, so a canceled context
+// (which makes every Invoke return promptly) cannot leak goroutines.
+func (l *Loop) invokeParallel(ctx context.Context, d *tool.Dispatcher, calls []agent.ToolCall, idxs []int, out []ToolOutcome) {
+	if len(idxs) == 0 {
+		return
+	}
+	sem := make(chan struct{}, l.toolParallelism)
+	var wg sync.WaitGroup
+	for _, i := range idxs {
+		wg.Add(1)
+		sem <- struct{}{}
+		go func(i int) {
+			defer wg.Done()
+			defer func() { <-sem }()
+			out[i] = l.invokeOne(ctx, d, calls[i])
+		}(i)
+	}
+	wg.Wait()
+}
+
+// returned by classifyToolBatch for the two skip reasons.
+func duplicateCallReason() string {
+	return "duplicate call with identical arguments already issued in this batch"
+}
+
+func repeatedCallReason() string {
+	return "already used with identical arguments in a previous round; do not repeat it"
+}
+
+// skippedOutcome builds a Skipped outcome carrying the human reason.
+func skippedOutcome(reason string) ToolOutcome {
+	if reason == "" {
+		reason = "tool call skipped"
+	}
+	return ToolOutcome{Skipped: true, Reason: reason}
+}
+
+// shouldTerminateBatch reports whether every call in the batch asked to terminate
+// (OpenClaw's shouldTerminateToolBatch), so a hook can stop the round.
+func shouldTerminateBatch(outcomes []ToolOutcome) bool {
+	if len(outcomes) == 0 {
+		return false
+	}
+	for _, o := range outcomes {
+		if !o.Terminate {
+			return false
+		}
+	}
+	return true
+}
+
+// toolFingerprint canonicalizes a tool call (name + args) so identical calls can
+// be detected. Args are JSON-marshaled, so equivalent objects with different key
+// orders collapse to the same fingerprint; a marshal failure falls back to %v.
+func toolFingerprint(call agent.ToolCall) string {
+	b, err := json.Marshal(call.Args)
+	if err != nil {
+		b = []byte(fmt.Sprintf("%v", call.Args))
+	}
+	return call.Name + "\x00" + string(b)
+}
+
+// errorKind classifies an invocation error into a tool.Kind* label so the model
+// can distinguish an argument-validation failure (re-issue a corrected call) from
+// an execution failure. A nil error yields "" (success).
+func errorKind(err error) string {
+	if err == nil {
+		return ""
+	}
+	var te *tool.ToolError
+	if errors.As(err, &te) {
+		return te.Kind()
+	}
+	if errors.Is(err, tool.ErrInvalidArgs) {
+		return tool.KindArgumentValidation
+	}
+	return tool.KindExecution
 }
 
 // dispatcher returns the loop's tool dispatcher, falling back to the agent's own
@@ -58,15 +400,32 @@ func (l *Loop) dispatcher() *tool.Dispatcher {
 }
 
 // toolResultMessage renders a tool call's outcome as a RoleTool message ready to
-// be fed back to the model. Errors are included in the text so the LLM can
-// react to a failed or timed-out call.
-func toolResultMessage(tc agent.ToolCall, result any, invokeErr error) model.Message {
-	text := fmt.Sprintf("tool %s result: %s", tc.Name, formatToolResult(result))
-	if invokeErr != nil {
-		text = fmt.Sprintf("tool %s failed: %v", tc.Name, invokeErr)
-	}
+// be fed back to the model. Skipped calls carry their reason; failures carry a
+// structured {kind,message} so the LLM can react appropriately; success carries
+// the value.
+func toolResultMessage(tc agent.ToolCall, out ToolOutcome) model.Message {
 	return model.Message{Role: model.RoleTool, ToolCallName: tc.Name,
-		Content: []model.Content{{Type: model.ContentTypeText, Text: text}}}
+		Content: []model.Content{{Type: model.ContentTypeText, Text: toolResultText(tc, out)}}}
+}
+
+// toolResultText renders the text payload of a tool result message.
+func toolResultText(tc agent.ToolCall, out ToolOutcome) string {
+	switch {
+	case out.Skipped:
+		if out.Reason == "" {
+			return fmt.Sprintf("tool %s skipped", tc.Name)
+		}
+		return fmt.Sprintf("tool %s skipped: %s", tc.Name, out.Reason)
+	case out.Err != nil:
+		if kind := out.ErrKind; kind != "" {
+			if payload, err := json.Marshal(map[string]string{"kind": kind, "message": out.Err.Error()}); err == nil {
+				return fmt.Sprintf("tool %s failed: %s", tc.Name, payload)
+			}
+		}
+		return fmt.Sprintf("tool %s failed: %v", tc.Name, out.Err)
+	default:
+		return fmt.Sprintf("tool %s result: %s", tc.Name, formatToolResult(out.Result))
+	}
 }
 
 // formatToolResult renders a tool return value as text for the model. Strings are

internal/runtime/tool/repair.go

@@ -0,0 +1,113 @@
+package tool
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"regexp"
+)
+
+// fencedJSONRe matches a code-fence wrapper some models emit around tool-call
+// JSON, e.g. ```json {...} ```. The captured group is the inner JSON.
+var fencedJSONRe = regexp.MustCompile("(?s)^[\\s`]*```(?:json)?[\\r\\n]*(.*?)[\\r\\n]*```\\s*$")
+
+// LenientJSONUnmarshal unmarshals raw into dest, applying a few tolerant repairs
+// for the malformed tool-call JSON models sometimes emit, before falling back to
+// strict encoding/json. Repairs are applied in order:
+//
+//  1. strip a wrapping ```json code fence (and stray backticks);
+//  2. trim surrounding whitespace;
+//  3. strip trailing commas before `}` and `]`;
+//  4. attempt the strict decode.
+//
+// The function reports the raw json.Unmarshal error (wrapped) when every repair
+// fails, so a caller can fall back to treating the payload as plain text without
+// crashing — the malformed call never aborts the round. Full repair (unquoted
+// keys, single-quoted strings, smart quotes) is deliberately left for a later
+// milestone; the load-bearing guarantee here is that a malformed envelope is
+// recoverable or degrades to text rather than throwing.
+func LenientJSONUnmarshal(raw []byte, dest any) error {
+	candidates := repairCandidates(raw)
+	var lastErr error
+	for _, c := range candidates {
+		if err := json.Unmarshal(c, dest); err == nil {
+			return nil
+		} else {
+			lastErr = err
+		}
+	}
+	return fmt.Errorf("tool: lenient json: %w", lastErr)
+}
+
+// repairCandidates returns the ordered list of byte slices to try, deduplicated:
+// the raw input, the fenced-stripped input, and trailing-comma-stripped variants.
+func repairCandidates(raw []byte) [][]byte {
+	out := [][]byte{nil}
+	seen := map[string]bool{}
+	push := func(b []byte) {
+		s := string(b)
+		if seen[s] {
+			return
+		}
+		seen[s] = true
+		out = append(out, b)
+	}
+
+	push(bytes.TrimSpace(raw))
+
+	clean := raw
+	if m := fencedJSONRe.FindSubmatch(raw); len(m) == 2 {
+		clean = bytes.TrimSpace(m[1])
+		push(clean)
+	}
+	clean = bytes.TrimSpace(clean)
+	push(bytes.TrimSpace(clean))
+	push(bytes.TrimSpace(stripTrailingCommas(clean)))
+	push(bytes.TrimSpace(stripTrailingCommas(bytes.TrimSpace(raw))))
+
+	return out
+}
+
+// stripTrailingCommas removes commas that sit immediately before a closing `}`
+// or `]` (ignoring whitespace), the most common single-token repair for truncated
+// model output such as `{"a":1,}`.
+func stripTrailingCommas(b []byte) []byte {
+	if !bytes.ContainsAny(b, "}]") {
+		return b
+	}
+	// Scan for a comma run whose next non-whitespace byte is a closing bracket; a
+	// copy is built so the original bytes are never mutated.
+	out := make([]byte, 0, len(b))
+	skipComma := false
+	for i := 0; i < len(b); i++ {
+		if b[i] == ',' {
+			// Peek ahead past whitespace for a closing bracket.
+			j := i + 1
+			for j < len(b) && isJSONSpace(b[j]) {
+				j++
+			}
+			if j < len(b) && (b[j] == '}' || b[j] == ']') {
+				skipComma = true
+			}
+		}
+		if skipComma && isJSONSpace(b[i]) {
+			continue
+		}
+		if skipComma && b[i] == ',' {
+			skipComma = false
+			continue
+		}
+		out = append(out, b[i])
+	}
+	return out
+}
+
+// isJSONSpace reports whether b is JSON insignificant whitespace.
+func isJSONSpace(b byte) bool {
+	switch b {
+	case ' ', '\t', '\r', '\n':
+		return true
+	default:
+		return false
+	}
+}

internal/runtime/tool/tool.go

@@ -25,6 +25,28 @@ import (
 // override and the Dispatcher was built without WithDefaultTimeout.
 const DefaultTimeout = 30 * time.Second
 
+// Execution modes a tool may declare to the loop. A tool that mutates shared
+// state (file writes, device control) should be marked sequential so the loop
+// does not run it concurrently with other calls.
+const (
+	// ExecutionModeParallel is the default: the loop may run such a tool
+	// concurrently with other calls in a batch.
+	ExecutionModeParallel = "parallel"
+	// ExecutionModeSequential forces the loop to run the whole batch serially so
+	// this tool is never invoked concurrently.
+	ExecutionModeSequential = "sequential"
+)
+
+// Error-kind labels distinguishing why a tool call failed, fed back to the model
+// as a structured {kind,message} so it can react differently to a bad argument
+// (re-issue a corrected call) versus an execution failure.
+const (
+	// KindArgumentValidation marks a JSON-Schema argument-validation failure.
+	KindArgumentValidation = "argument-validation"
+	// KindExecution marks a runtime execution failure (timeout, panic, tool error).
+	KindExecution = "execution"
+)
+
 // Sentinel errors returned by the Dispatcher. Use errors.Is to test for them;
 // they are wrapped with %w so the underlying cause stays available.
 var (
@@ -64,6 +86,17 @@ func (e *ToolError) Error() string {
 // Unwrap exposes the wrapped cause so errors.Is/errors.As traverse the chain.
 func (e *ToolError) Unwrap() error { return e.cause }
 
+// Kind classifies the failure as "argument-validation" (the caller-supplied
+// arguments failed the JSON Schema) or "execution" (anything after validation:
+// unknown tool, timeout, panic or an Execute error). The loop uses it to feed a
+// structured {kind,message} tool result back to the model.
+func (e *ToolError) Kind() string {
+	if e.cause != nil && errors.Is(e.cause, ErrInvalidArgs) {
+		return KindArgumentValidation
+	}
+	return KindExecution
+}
+
 // Option configures a Dispatcher at construction time.
 type Option func(*Dispatcher)
 
@@ -72,8 +105,9 @@ type Option func(*Dispatcher)
 type Dispatcher struct {
 	reg      *registry.Registry
 	dft      time.Duration
-	mu       sync.RWMutex // guards timeouts
+	mu       sync.RWMutex // guards timeouts and modes
 	timeouts map[string]time.Duration
+	modes    map[string]string // tool name -> ExecutionMode* (default parallel)
 }
 
 // New builds a Dispatcher backed by reg, applying opts in order. It returns an
@@ -87,6 +121,7 @@ func New(reg *registry.Registry, opts ...Option) (*Dispatcher, error) {
 		reg:      reg,
 		dft:      DefaultTimeout,
 		timeouts: make(map[string]time.Duration),
+		modes:    make(map[string]string),
 	}
 	for _, opt := range opts {
 		if opt != nil {
@@ -125,6 +160,33 @@ func (d *Dispatcher) SetToolTimeout(name string, timeout time.Duration) error {
 	return nil
 }
 
+// SetToolExecutionMode marks a tool as running "sequential" or "parallel" (the
+// default). A sequential tool is never invoked concurrently by the loop, so
+// shared-state tools (file writes, device control) can declare it. An empty mode
+// clears the override back to the default. Only ExecutionModeSequential is
+// treated as sequential.
+func (d *Dispatcher) SetToolExecutionMode(name, mode string) error {
+	if name == "" {
+		return fmt.Errorf("tool: set execution mode: %w", ErrUnknownTool)
+	}
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	if mode == "" || mode == ExecutionModeParallel {
+		delete(d.modes, name)
+		return nil
+	}
+	d.modes[name] = mode
+	return nil
+}
+
+// IsSequential reports whether the named tool has been declared sequential. An
+// unknown name or one never marked sequential reports false (the default).
+func (d *Dispatcher) IsSequential(name string) bool {
+	d.mu.RLock()
+	defer d.mu.RUnlock()
+	return d.modes[name] == ExecutionModeSequential
+}
+
 // Invoke executes the tool registered as name with the given args. It resolves
 // the tool from the registry, validates args against the tool's Parameters JSON
 // Schema, and runs Execute under the tool's deadline (per-tool override, else

internal/runtime/tool/tool_extra_test.go

@@ -0,0 +1,87 @@
+package tool
+
+import (
+	"errors"
+	"fmt"
+	"testing"
+)
+
+func TestLenientJSONUnmarshal_TrailingComma(t *testing.T) {
+	t.Parallel()
+	var v map[string]any
+	if err := LenientJSONUnmarshal([]byte(`{"a":1,}`), &v); err != nil {
+		t.Fatalf("LenientJSONUnmarshal: %v", err)
+	}
+	if v["a"] != float64(1) {
+		t.Fatalf("a = %#v, want 1", v["a"])
+	}
+}
+
+func TestLenientJSONUnmarshal_Fenced(t *testing.T) {
+	t.Parallel()
+	raw := "```json\n{\"tool_calls\":[{\"name\":\"echo\",\"args\":{\"q\":\"hi\"}}]}\n```"
+	var v struct {
+		ToolCalls []map[string]any `json:"tool_calls"`
+	}
+	if err := LenientJSONUnmarshal([]byte(raw), &v); err != nil {
+		t.Fatalf("LenientJSONUnmarshal: %v", err)
+	}
+	if len(v.ToolCalls) != 1 {
+		t.Fatalf("tool_calls = %d, want 1", len(v.ToolCalls))
+	}
+}
+
+func TestLenientJSONUnmarshal_Unrecoverable(t *testing.T) {
+	t.Parallel()
+	// Malformed beyond repair must return an error, never panic or silently
+	// succeed.
+	var v map[string]any
+	if err := LenientJSONUnmarshal([]byte(`{"a":"unterminated`), &v); err == nil {
+		t.Fatal("expected error for unrecoverable JSON")
+	}
+}
+
+func TestSetToolExecutionMode_Sequential(t *testing.T) {
+	t.Parallel()
+	d, _ := newDispatcher(t)
+	if d.IsSequential("x") {
+		t.Fatal("x should default to parallel")
+	}
+	if err := d.SetToolExecutionMode("x", ExecutionModeSequential); err != nil {
+		t.Fatalf("SetToolExecutionMode: %v", err)
+	}
+	if !d.IsSequential("x") {
+		t.Fatal("x should be sequential after marking")
+	}
+	// Clearing back to parallel.
+	if err := d.SetToolExecutionMode("x", ExecutionModeParallel); err != nil {
+		t.Fatalf("SetToolExecutionMode(parallel): %v", err)
+	}
+	if d.IsSequential("x") {
+		t.Fatal("x should be parallel after clearing")
+	}
+}
+
+func TestSetToolExecutionMode_EmptyName(t *testing.T) {
+	t.Parallel()
+	d, _ := newDispatcher(t)
+	if err := d.SetToolExecutionMode("", ExecutionModeSequential); !errors.Is(err, ErrUnknownTool) {
+		t.Fatalf("SetToolExecutionMode(\"\") error = %v, want ErrUnknownTool", err)
+	}
+}
+
+func TestToolError_Kind(t *testing.T) {
+	t.Parallel()
+	val := &ToolError{Name: "x", Message: "bad args", cause: fmt.Errorf("validate: %w", ErrInvalidArgs)}
+	if val.Kind() != KindArgumentValidation {
+		t.Fatalf("validation Kind = %q, want %q", val.Kind(), KindArgumentValidation)
+	}
+	exec := &ToolError{Name: "x", Message: "boom", cause: errors.New("boom")}
+	if exec.Kind() != KindExecution {
+		t.Fatalf("execution Kind = %q, want %q", exec.Kind(), KindExecution)
+	}
+	none := &ToolError{Name: "x", Message: "m"}
+	if none.Kind() != KindExecution {
+		t.Fatalf("nil-cause Kind = %q, want %q", none.Kind(), KindExecution)
+	}
+}