diff --git a/internal/agent/core/process.go b/internal/agent/core/process.go
index 529a036..1649d16 100644
--- a/internal/agent/core/process.go
+++ b/internal/agent/core/process.go
@@ -308,7 +308,11 @@ func (a *Agent) process(input string, stageCtx *sdk.StageContext) (response stri
 			// ContextPolicy: prune 工具调用后执行上下文裁剪（§13.8）
 			if def := a.stageHost.ToolDef(tc.Name); def != nil && def.ContextPolicy == "prune" {
 				if a.context != nil {
-					a.context.Prune(result, 20, a.docStore)
+					topK := a.maxContextSize - 1
+					if topK < 1 {
+						topK = 1
+					}
+					a.context.Prune(result, topK, a.docStore)
 				}
 			}
 
diff --git a/internal/plugin/proc/corehandler.go b/internal/plugin/proc/corehandler.go
index 49b6e28..a222020 100644
--- a/internal/plugin/proc/corehandler.go
+++ b/internal/plugin/proc/corehandler.go
@@ -154,28 +154,28 @@ func (h *coreHandler) Handle(method string, params json.RawMessage) (interface{}
 		if err := unmarshal(params, &p); err != nil {
 			return nil, err
 		}
-		h.sdk.InjectText(p.Source, p.Channel, p.Text)
+		h.sdk.InjectText(p.Source, p.Channel, h.resolveText(p))
 		return nil, nil
 	case MethodIOInjectInterrupt:
 		var p injectParams
 		if err := unmarshal(params, &p); err != nil {
 			return nil, err
 		}
-		h.sdk.InjectInterruptText(p.Source, p.Channel, p.Text)
+		h.sdk.InjectInterruptText(p.Source, p.Channel, h.resolveText(p))
 		return nil, nil
 	case MethodIOInjectTextNoMem:
 		var p injectParams
 		if err := unmarshal(params, &p); err != nil {
 			return nil, err
 		}
-		h.sdk.InjectTextNoMemory(p.Source, p.Channel, p.Text)
+		h.sdk.InjectTextNoMemory(p.Source, p.Channel, h.resolveText(p))
 		return nil, nil
 	case MethodIOInjectSync:
 		var p injectParams
 		if err := unmarshal(params, &p); err != nil {
 			return nil, err
 		}
-		return map[string]interface{}{"reply": h.sdk.InjectInputSync(p.Source, p.Channel, p.Text)}, nil
+		return map[string]interface{}{"reply": h.sdk.InjectInputSync(p.Source, p.Channel, h.resolveText(p))}, nil
 
 	case MethodIOInjectMedia:
 		var p injectMediaParams
@@ -563,7 +563,7 @@ func (h *coreHandler) Handle(method string, params json.RawMessage) (interface{}
 // 否则使用内联 Text。兼容新旧两种协议。
 func (h *coreHandler) resolveText(p injectParams) string {
 	if !p.TextRef.IsZero() {
-		return string(p.TextRef.Slice(h.host.data))
+		return string(h.host.unified.arenaRead(p.TextRef))
 	}
 	return p.Text
 }
@@ -610,6 +610,12 @@ func (h *coreHandler) cleanerProxy(scope, name string, enabled bool) (func(strin
 		return nil, fmt.Errorf("%s %s 声明 Cleaner，但清洗回调通道未就绪", scope, name)
 	}
 	return func(text string) string {
+		// Cleaner 输入和输出共享同一 arena。串行覆盖完整往返，保证结果读完前
+		// 不被其他调用重置；返回 string 会复制结果，随后即可回收整个临时区。
+		h.host.arenaMu.Lock()
+		defer h.host.arenaMu.Unlock()
+		defer h.host.unified.arenaReset()
+
 		ref, err := h.host.unified.arenaWrite([]byte(text))
 		if err != nil {
 			return text
@@ -619,6 +625,9 @@ func (h *coreHandler) cleanerProxy(scope, name string, enabled bool) (func(strin
 			return text
 		}
 		result := h.host.unified.arenaRead(resultRef)
+		if result == nil && !resultRef.IsZero() {
+			return text
+		}
 		return string(result)
 	}, nil
 }
@@ -636,6 +645,11 @@ func (h *coreHandler) toolRegister(params json.RawMessage) (interface{}, error)
 	if p.Name == "" {
 		return nil, fmt.Errorf("tool.register: 缺少 name")
 	}
+	switch p.Def.ContextPolicy {
+	case "", "none", "prune":
+	default:
+		return nil, fmt.Errorf("tool.register: context_policy 只允许 none/prune，实际 %q", p.Def.ContextPolicy)
+	}
 	p.Def.Plugin = h.name
 	// 函数本身不进 JSON；has_cleaner 只声明其存在，实际执行回到插件进程。
 	cleaner, err := h.cleanerProxy(CleanerScopeTool, p.Name, p.HasCleaner)
diff --git a/internal/plugin/proc/host.go b/internal/plugin/proc/host.go
index 4620aaf..78c7037 100644
--- a/internal/plugin/proc/host.go
+++ b/internal/plugin/proc/host.go
@@ -36,6 +36,7 @@ type Host struct {
 
 	evtSubscriber EvtRingSubscriber
 	locks         *lockRegistry
+	arenaMu       sync.Mutex // 动态 arena 跨进程调用的生命周期锁
 	stageMu       sync.Mutex
 	coordMu       sync.Mutex
 	coord         *stageCoordinator
diff --git a/internal/plugin/proc/toollane.go b/internal/plugin/proc/toollane.go
index b365962..ca3428e 100644
--- a/internal/plugin/proc/toollane.go
+++ b/internal/plugin/proc/toollane.go
@@ -47,10 +47,11 @@ const (
 	toolFrameSize      = 112 // 单帧总大小
 
 	// 帧状态
-	toolFrameFree    uint32 = 0
-	toolFrameCalling uint32 = 1 // 内核写 input，插件待读
-	toolFrameReading uint32 = 2 // 插件正在执行
-	toolFrameReady   uint32 = 3 // 插件写 output，内核待读
+	toolFrameFree     uint32 = 0
+	toolFrameReserved uint32 = 1 // 内核已占帧，正在写入元数据
+	toolFrameCalling  uint32 = 2 // 内核写完 input，插件待读
+	toolFrameReading  uint32 = 3 // 插件正在执行
+	toolFrameReady    uint32 = 4 // 插件写完 output，内核待读
 )
 
 // ToolRing 头偏移（相对区域起始）
@@ -116,10 +117,19 @@ func AttachToolRing(data []byte) (*ToolCallRing, error) {
 	if magic != toolRingMagic {
 		return nil, fmt.Errorf("tool ring: 魔数不匹配（0x%x）", magic)
 	}
+	cap := getU32(data[trlOffCap:])
+	frameSize := getU32(data[trlOffFrameSize:])
+	version := getU32(data[trlOffVersion:])
+	if version != toolRingVersion {
+		return nil, fmt.Errorf("tool ring: 版本不匹配（%d，期望 %d）", version, toolRingVersion)
+	}
+	if cap == 0 || frameSize != toolFrameSize || uint64(trlOffFrameBase)+uint64(cap)*uint64(frameSize) > uint64(len(data)) {
+		return nil, fmt.Errorf("tool ring: 布局非法（cap=%d frameSize=%d total=%d）", cap, frameSize, len(data))
+	}
 	return &ToolCallRing{
 		data:       data,
-		cap:        getU32(data[trlOffCap:]),
-		frameSize:  getU32(data[trlOffFrameSize:]),
+		cap:        cap,
+		frameSize:  frameSize,
 		framesBase: trlOffFrameBase,
 	}, nil
 }
@@ -128,13 +138,11 @@ func AttachToolRing(data []byte) (*ToolCallRing, error) {
 //
 // 环形扫描：从 writeIdx 开始，绕环一圈找 FREE 帧。全部忙时背压。
 func (r *ToolCallRing) Reserve() (frameIdx uint32, err error) {
-	start := r.writeIdx.Load()
+	start := r.writeIdx.Add(1) - 1
 	for i := uint64(0); i < uint64(r.cap); i++ {
 		idx := start + i
 		fi := uint32(idx % uint64(r.cap))
-		state := atomic.LoadUint32(r.statePtr(fi))
-		if state == toolFrameFree {
-			r.writeIdx.Store(idx + 1)
+		if atomic.CompareAndSwapUint32(r.statePtr(fi), toolFrameFree, toolFrameReserved) {
 			return fi, nil
 		}
 	}
@@ -191,16 +199,20 @@ func (r *ToolCallRing) GetCallingFrame(frameIdx uint32) (name string, inputRef S
 	return
 }
 
-// SetReading 将帧状态设为 READING（插件开始执行）。
-func (r *ToolCallRing) SetReading(frameIdx uint32) {
-	atomic.StoreUint32(r.statePtr(frameIdx), toolFrameReading)
+// SetReading 将 CALLING 帧原子转为 READING（插件开始执行）。
+func (r *ToolCallRing) SetReading(frameIdx uint32) bool {
+	return atomic.CompareAndSwapUint32(r.statePtr(frameIdx), toolFrameCalling, toolFrameReading)
 }
 
-// SetReady 将帧状态设为 READY 并写入 output 描述符（插件执行完毕）。
-func (r *ToolCallRing) SetReady(frameIdx uint32, outputRef SharedRef) {
+// SetReady 将 READING 帧设为 READY 并写入 output 描述符（插件执行完毕）。
+func (r *ToolCallRing) SetReady(frameIdx uint32, outputRef SharedRef) bool {
+	if atomic.LoadUint32(r.statePtr(frameIdx)) != toolFrameReading {
+		return false
+	}
 	off := r.frameOff(frameIdx)
 	packSharedRef(r.data[off+toolFrameOffOutput:], outputRef)
 	atomic.StoreUint32(r.statePtr(frameIdx), toolFrameReady)
+	return true
 }
 
 // GetReadyFrame 读取帧的 requestID 和 output 描述符（内核消费 READY 帧）。
@@ -214,8 +226,8 @@ func (r *ToolCallRing) GetReadyFrame(frameIdx uint32) (reqID uint64, outputRef S
 // ReleaseFrame 回收帧为 FREE（内核消费完毕后调用）。
 func (r *ToolCallRing) ReleaseFrame(frameIdx uint32) {
 	off := r.frameOff(frameIdx)
-	// 清零帧内容
-	for i := uint32(0); i < r.frameSize; i++ {
+	// state 必须最后发布 FREE；否则并发 Reserve 可能在其余字段尚未清零时复用帧。
+	for i := uint32(4); i < r.frameSize; i++ {
 		r.data[off+i] = 0
 	}
 	atomic.StoreUint32(r.statePtr(frameIdx), toolFrameFree)
diff --git a/internal/plugin/proc/toollane_test.go b/internal/plugin/proc/toollane_test.go
index be8074a..c722513 100644
--- a/internal/plugin/proc/toollane_test.go
+++ b/internal/plugin/proc/toollane_test.go
@@ -1,6 +1,7 @@
 package proc
 
 import (
+	"sync"
 	"testing"
 	"unsafe"
 )
@@ -154,6 +155,56 @@ func TestSharedRef_PackUnpack(t *testing.T) {
 	}
 }
 
+func TestToolCallRing_ConcurrentReserveUnique(t *testing.T) {
+	data := make([]byte, int(trlOffFrameBase+toolRingCap*toolFrameSize))
+	if err := InitToolRing(data); err != nil {
+		t.Fatal(err)
+	}
+	ring, err := AttachToolRing(data)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	indices := make(chan uint32, toolRingCap)
+	var wg sync.WaitGroup
+	for i := uint32(0); i < toolRingCap; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			idx, reserveErr := ring.Reserve()
+			if reserveErr != nil {
+				t.Errorf("Reserve: %v", reserveErr)
+				return
+			}
+			indices <- idx
+		}()
+	}
+	wg.Wait()
+	close(indices)
+
+	seen := make(map[uint32]bool, toolRingCap)
+	for idx := range indices {
+		if seen[idx] {
+			t.Fatalf("并发 Reserve 重复分配帧 %d", idx)
+		}
+		seen[idx] = true
+	}
+	if len(seen) != int(toolRingCap) {
+		t.Fatalf("唯一帧数=%d，期望 %d", len(seen), toolRingCap)
+	}
+}
+
+func TestAttachToolRingRejectsInvalidLayout(t *testing.T) {
+	data := make([]byte, trlOffFrameBase)
+	putU32(data[trlOffMagic:], toolRingMagic)
+	putU32(data[trlOffVersion:], toolRingVersion)
+	putU32(data[trlOffCap:], toolRingCap)
+	putU32(data[trlOffFrameSize:], toolFrameSize)
+	if _, err := AttachToolRing(data); err == nil {
+		t.Fatal("越界布局应被拒绝")
+	}
+}
+
 func TestToolFrameLayoutAligned(t *testing.T) {
 	// 确保帧布局字段偏移与内存布局一致（安全断言）
 	var frame toolFrame
diff --git a/internal/plugin/proc/unified.go b/internal/plugin/proc/unified.go
index 3c1969c..0f3bf63 100644
--- a/internal/plugin/proc/unified.go
+++ b/internal/plugin/proc/unified.go
@@ -94,10 +94,11 @@ func (r SharedRef) IsZero() bool {
 
 // Slice 从共享内存中按 SharedRef 切片。data 必须是完整的 mmap 区域。
 func (r SharedRef) Slice(data []byte) []byte {
-	if r.IsZero() || int(r.Offset)+int(r.Length) > len(data) {
+	end := uint64(r.Offset) + uint64(r.Length)
+	if r.IsZero() || end > uint64(len(data)) {
 		return nil
 	}
-	return data[r.Offset : r.Offset+r.Length]
+	return data[r.Offset:uint32(end)]
 }
 
 // unifiedRegion 统一共享内存区域的内核侧视图。
@@ -171,12 +172,22 @@ func attachUnifiedRegion(data []byte) (*unifiedRegion, error) {
 	evtOff := getU32(data[sbOffEvtOff:])
 	evtSize := getU32(data[sbOffEvtSize:])
 
+	capacity := getU32(data[sbOffCapacity:])
 	arenaOff := getU32(data[sbOffArenaOff:])
 	arenaCap := getU32(data[sbOffArenaCap:])
 
-	if int(evtOff)+int(evtSize) > len(data) {
+	if capacity != uint32(len(data)) {
+		return nil, fmt.Errorf("unified: capacity 不匹配（header=%d mapped=%d）", capacity, len(data))
+	}
+	if uint64(ctxOff)+uint64(ctxSize) > uint64(len(data)) {
+		return nil, fmt.Errorf("unified: StageContext 越界（off=%d size=%d total=%d）", ctxOff, ctxSize, len(data))
+	}
+	if uint64(evtOff)+uint64(evtSize) > uint64(len(data)) {
 		return nil, fmt.Errorf("unified: EvtRing 越界（off=%d size=%d total=%d）", evtOff, evtSize, len(data))
 	}
+	if uint64(arenaOff)+uint64(arenaCap) > uint64(len(data)) {
+		return nil, fmt.Errorf("unified: arena 越界（off=%d cap=%d total=%d）", arenaOff, arenaCap, len(data))
+	}
 
 	return &unifiedRegion{
 		data:     data,
@@ -248,16 +259,19 @@ func (r *unifiedRegion) arenaAlloc(n int) (uint32, error) {
 	if n <= 0 {
 		return 0, fmt.Errorf("arena: 非法分配长度 %d", n)
 	}
-	used := atomic.LoadUint32(r.arenaUsed)
-	if used == 0 {
-		used = 1
+	for {
+		used := atomic.LoadUint32(r.arenaUsed)
+		if used == 0 {
+			used = 1
+		}
+		end := uint64(used) + uint64(n)
+		if end > uint64(r.arenaCap) {
+			return 0, fmt.Errorf("arena: 空间不足（需 %d，剩 %d）", n, uint64(r.arenaCap)-uint64(used))
+		}
+		if atomic.CompareAndSwapUint32(r.arenaUsed, used, uint32(end)) {
+			return used, nil
+		}
 	}
-	end := uint64(used) + uint64(n)
-	if end > uint64(r.arenaCap) {
-		return 0, fmt.Errorf("arena: 空间不足（需 %d，剩 %d）", n, uint64(r.arenaCap)-uint64(used))
-	}
-	atomic.StoreUint32(r.arenaUsed, uint32(end))
-	return used, nil
 }
 
 // arenaWrite 把 b 写入动态 arena 并返回 SharedRef。
@@ -275,8 +289,16 @@ func (r *unifiedRegion) arenaWrite(b []byte) (SharedRef, error) {
 	return SharedRef{Offset: base, Length: uint32(len(b)), Generation: gen}, nil
 }
 
-// arenaRead 按 SharedRef 读取数据。
+// arenaRead 按 SharedRef 读取数据。generation 不匹配或引用越出 arena 时拒绝。
 func (r *unifiedRegion) arenaRead(ref SharedRef) []byte {
+	if ref.IsZero() || ref.Generation != uint32(r.generation()) {
+		return nil
+	}
+	end := uint64(ref.Offset) + uint64(ref.Length)
+	arenaEnd := uint64(r.arenaOff) + uint64(r.arenaCap)
+	if uint64(ref.Offset) < uint64(r.arenaOff)+1 || end > arenaEnd {
+		return nil
+	}
 	return ref.Slice(r.data)
 }