diff --git a/docs/feature/self-update-recovery-fixes.md b/docs/feature/self-update-recovery-fixes.md
index 7d623df8..8a218a55 100644
--- a/docs/feature/self-update-recovery-fixes.md
+++ b/docs/feature/self-update-recovery-fixes.md
@@ -34,3 +34,11 @@ Compatibility: properly written current journals remain readable, legacy plain-t
 4. Run update/handler targeted suites and race checks, full Go tests, build, JS and shell checks; update changelog and verification record. Open a corrective PR and integrate the verified patch as part of the authorized merge-and-fix task, respecting repository checks.
 
 Docs: this phase record plus concise behavior notes in deployment/developer documentation if needed. No screenshots or production external services are required; tests use local Git and harmless command/HTTP markers. No version bump, tag or release publication.
+
+## Implementation (F4)
+
+Implemented strict recovery decoding in recovery_evidence.go, with exact field names, nested duplicate/type/null checks, commit/hash validation and State reconciliation. Build recovery verifies pre-move versus post-move binary evidence before content restore and rechecks files after compilation. Fresh rollback and legacy-marker recovery also read State strictly. Self-contained rollback journals validate absence/hash coherence even after State cleanup, and actual absence is checked before any cleanup.
+
+MCP edits distinguish omitted activation fields from explicit booleans. Omitted fields preserve the manager state; Start/Stop and persisted disabled are synchronized so restart retains the requested state. Existing environment snapshot expansion is preserved.
+
+Tests added for malformed build/rollback journals, all independent review counterexamples, valid partial binary rename and final cleanup retries, and MCP stop/edit/start plus config reload. Targeted reproductions pass; original full Go, build, five-package race, and 277 JS checks passed before final evidence guard refinements. Final exact-patch validation follows in F5. No production external service was contacted.
diff --git a/internal/handler/external_mcp.go b/internal/handler/external_mcp.go
index 0da18210..42cfb41b 100644
--- a/internal/handler/external_mcp.go
+++ b/internal/handler/external_mcp.go
@@ -179,13 +179,10 @@ func (h *ExternalMCPHandler) AddOrUpdateExternalMCP(c *gin.Context) {
 
 	cfg := req.Config
 
-	// 官方 disabled 字段 → ExternalMCPEnable 取反
-	if cfg.Disabled {
-		cfg.ExternalMCPEnable = false
-	} else if !cfg.ExternalMCPEnable {
-		// 用户未显式设置 external_mcp_enable，官方配置默认就是启用的
-		cfg.ExternalMCPEnable = true
-	}
+	// Editing metadata does not change activation unless the request says so.
+	previous, exists := h.manager.GetConfigs()[name]
+	cfg.ExternalMCPEnable = req.activation(previous.ExternalMCPEnable, exists)
+	cfg.Disabled = !cfg.ExternalMCPEnable
 
 	// 展开 ${VAR} 环境变量
 	config.ExpandConfigEnv(&cfg)
@@ -272,6 +269,7 @@ func (h *ExternalMCPHandler) StartExternalMCP(c *gin.Context) {
 	}
 	cfg := h.config.ExternalMCP.Servers[name]
 	cfg.ExternalMCPEnable = true
+	cfg.Disabled = false
 	h.config.ExternalMCP.Servers[name] = cfg
 
 	// 保存到配置文件
@@ -326,6 +324,7 @@ func (h *ExternalMCPHandler) StopExternalMCP(c *gin.Context) {
 	}
 	cfg := h.config.ExternalMCP.Servers[name]
 	cfg.ExternalMCPEnable = false
+	cfg.Disabled = true
 	h.config.ExternalMCP.Servers[name] = cfg
 
 	// 保存到配置文件
@@ -496,7 +495,9 @@ func setStringArrayInMap(mapNode *yaml.Node, key string, values []string) {
 
 // AddOrUpdateExternalMCPRequest 添加或更新外部MCP请求
 type AddOrUpdateExternalMCPRequest struct {
-	Config config.ExternalMCPServerConfig `json:"config"`
+	Config   config.ExternalMCPServerConfig `json:"config"`
+	enable   *bool
+	disabled *bool
 }
 
 // ExternalMCPResponse 外部MCP响应
diff --git a/internal/handler/external_mcp_activation_test.go b/internal/handler/external_mcp_activation_test.go
new file mode 100644
index 00000000..85bce887
--- /dev/null
+++ b/internal/handler/external_mcp_activation_test.go
@@ -0,0 +1,110 @@
+package handler
+
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"cyberstrike-ai/internal/config"
+)
+
+func TestMCPEditPreservesStoppedState(t *testing.T) {
+	router, h, path := setupTestRouter()
+	defer cleanupTestConfig(path)
+	defer h.manager.StopAll()
+	var calls atomic.Int64
+	called := make(chan struct{}, 16)
+	endpoint := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		calls.Add(1)
+		select {
+		case called <- struct{}{}:
+		default:
+		}
+		http.Error(w, "test endpoint", 503)
+	}))
+	defer endpoint.Close()
+	cfg := config.ExternalMCPServerConfig{Type: "http", URL: endpoint.URL, Description: "before"}
+	h.config.ExternalMCP.Servers["stopped"] = cfg
+	if err := h.manager.AddOrUpdateConfig("stopped", cfg); err != nil {
+		t.Fatal(err)
+	}
+	request := func(method, url string, body []byte) *httptest.ResponseRecorder {
+		t.Helper()
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest(method, url, bytes.NewReader(body))
+		r.Header.Set("Content-Type", "application/json")
+		router.ServeHTTP(w, r)
+		if w.Code != 200 {
+			t.Fatalf("%s %s: %d %s", method, url, w.Code, w.Body)
+		}
+		return w
+	}
+	request("POST", "/api/external-mcp/stopped/stop", nil)
+	// Shape emitted by the edit UI: enable omitted, descriptive metadata changed.
+	body, _ := json.Marshal(map[string]any{"config": map[string]any{"type": "http", "url": endpoint.URL, "description": "after"}})
+	request("PUT", "/api/external-mcp/stopped", body)
+	if h.manager.GetConfigs()["stopped"].ExternalMCPEnable {
+		t.Fatal("metadata edit enabled a stopped MCP")
+	}
+	persisted, err := config.Load(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if persisted.ExternalMCP.Servers["stopped"].ExternalMCPEnable {
+		t.Fatal("stop state lost on config reload")
+	}
+	select {
+	case <-called:
+		t.Fatal("metadata edit initiated a connection")
+	case <-time.After(100 * time.Millisecond):
+	}
+	if calls.Load() != 0 {
+		t.Fatal("stopped edit started external work")
+	}
+	request("POST", "/api/external-mcp/stopped/start", nil)
+	select {
+	case <-called:
+	case <-time.After(3 * time.Second):
+		t.Fatal("explicit Start did not connect")
+	}
+	if !h.manager.GetConfigs()["stopped"].ExternalMCPEnable {
+		t.Fatal("explicit Start stayed disabled")
+	}
+	persisted, err = config.Load(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !persisted.ExternalMCP.Servers["stopped"].ExternalMCPEnable {
+		t.Fatal("explicit Start not persisted")
+	}
+}
+
+func TestMCPRequestActivationPresence(t *testing.T) {
+	for _, tc := range []struct {
+		name, fields           string
+		previous, exists, want bool
+	}{
+		{"new default", "", false, false, true},
+		{"stopped edit", "", false, true, false},
+		{"running edit", "", true, true, true},
+		{"explicit enable", `,"external_mcp_enable":true`, false, true, true},
+		{"explicit stop", `,"external_mcp_enable":false`, true, true, false},
+		{"explicit disabled", `,"disabled":true`, true, true, false},
+		{"explicit enabled official", `,"disabled":false`, false, true, true},
+		{"disabled wins", `,"disabled":true,"external_mcp_enable":true`, true, true, false},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			var r AddOrUpdateExternalMCPRequest
+			if err := json.Unmarshal([]byte(`{"config":{"description":"edit"`+tc.fields+`}}`), &r); err != nil {
+				t.Fatal(err)
+			}
+			if got := r.activation(tc.previous, tc.exists); got != tc.want {
+				t.Fatalf("activation=%v want=%v", got, tc.want)
+			}
+		})
+	}
+}
diff --git a/internal/handler/external_mcp_request.go b/internal/handler/external_mcp_request.go
new file mode 100644
index 00000000..deebae8d
--- /dev/null
+++ b/internal/handler/external_mcp_request.go
@@ -0,0 +1,41 @@
+package handler
+
+import "encoding/json"
+
+// Keep omission distinct from false without changing the public request shape.
+func (r *AddOrUpdateExternalMCPRequest) UnmarshalJSON(data []byte) error {
+	type plain AddOrUpdateExternalMCPRequest
+	var decoded plain
+	if err := json.Unmarshal(data, &decoded); err != nil {
+		return err
+	}
+	var presence struct {
+		Config struct {
+			Enable   *bool `json:"external_mcp_enable"`
+			Disabled *bool `json:"disabled"`
+		} `json:"config"`
+	}
+	if err := json.Unmarshal(data, &presence); err != nil {
+		return err
+	}
+	*r = AddOrUpdateExternalMCPRequest(decoded)
+	r.enable = presence.Config.Enable
+	r.disabled = presence.Config.Disabled
+	return nil
+}
+
+func (r AddOrUpdateExternalMCPRequest) activation(previous, exists bool) bool {
+	if r.disabled != nil && *r.disabled {
+		return false
+	}
+	if r.enable != nil {
+		return *r.enable
+	}
+	if r.disabled != nil {
+		return !*r.disabled
+	}
+	if exists {
+		return previous
+	}
+	return true
+}
diff --git a/internal/update/apply.go b/internal/update/apply.go
index 8b7f2ddf..8d30f52e 100644
--- a/internal/update/apply.go
+++ b/internal/update/apply.go
@@ -73,12 +73,18 @@ func readBuildPending(root string) (buildPendingState, bool, error) {
 	if err != nil {
 		return st, true, err
 	}
-	if err := json.Unmarshal(data, &st); err != nil {
+	if err := decodeRecoveryJSON(data, &st); err != nil {
 		if strings.TrimSpace(string(data)) == "source is ahead of the binary" {
+			if _, _, stateErr := recoveryState(root); stateErr != nil {
+				return st, true, stateErr
+			}
 			return buildPendingState{Legacy: true}, true, nil
 		}
 		return buildPendingState{}, true, fmt.Errorf("待编译状态格式损坏: %w", err)
 	}
+	if err := validateBuildEvidence(root, st); err != nil {
+		return st, true, err
+	}
 	return st, true, nil
 }
 
@@ -476,6 +482,14 @@ func finishPendingBuild(ctx context.Context, snap *Snapshot, opts Options, res *
 	if err != nil {
 		return &Error{Reason: "bad_state", Message: "待编译状态里的提交不存在：" + pending.Commit}
 	}
+	fileEvidence := pending
+	if target != head {
+		// Before the source move only the original binary/absence is valid.
+		fileEvidence.BinarySHA256 = ""
+	}
+	if err := validateBuildFiles(bin, fileEvidence); err != nil {
+		return &Error{Reason: "bad_state", Message: "恢复证据不足，已保留二进制和记录：" + err.Error()}
+	}
 	if target != head {
 		if pending.PreviousCommit != "" {
 			previous, previousErr := gitCmd(ctx, snap.Root, "rev-parse", pending.PreviousCommit)
@@ -585,6 +599,9 @@ func buildAndSwap(ctx context.Context, root string, opts Options, res *Result, s
 		return &Error{Reason: "build_failed", Message: "无法校验新二进制：" + err.Error()}
 	}
 	bin := filepath.Join(root, opts.binaryName())
+	if err := validateBuildFiles(bin, pending); err != nil {
+		return &Error{Reason: "binary_changed", Message: "编译后恢复证据不再匹配，已保留现场：" + err.Error()}
+	}
 	if pending.Legacy && fileExists(bin) && fileExists(bin+".prev") {
 		currentHash, currentErr := fileSHA256(bin)
 		previousHash, previousErr := fileSHA256(bin + ".prev")
@@ -917,7 +934,10 @@ func Rollback(ctx context.Context, opts Options) (*Result, error) {
 			return nil, &Error{Reason: "moved_since_update", Message: "回滚中断后 HEAD 已经变了，拒绝覆盖后续提交"}
 		}
 	}
-	st, ok := readState(root)
+	st, ok, stateErr := recoveryState(root)
+	if stateErr != nil {
+		return nil, &Error{Reason: "state_unreadable", Message: "无法读取回滚状态：" + stateErr.Error()}
+	}
 	if !ok {
 		return nil, &Error{Reason: "no_state", Message: "没有可回滚的更新记录"}
 	}
diff --git a/internal/update/recovery_evidence.go b/internal/update/recovery_evidence.go
new file mode 100644
index 00000000..58b0368a
--- /dev/null
+++ b/internal/update/recovery_evidence.go
@@ -0,0 +1,260 @@
+package update
+
+import (
+	"bytes"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"io"
+	"os"
+	"reflect"
+	"strings"
+)
+
+// Recovery JSON authorizes filesystem mutations. Unlike encoding/json's default
+// behavior, repeated keys, case aliases, unknown fields and null scalars must not
+// silently replace or erase evidence. Slice nulls are emitted by our own writer.
+func decodeRecoveryJSON(data []byte, dst any) error {
+	dec := json.NewDecoder(bytes.NewReader(data))
+	if err := checkRecoveryValue(dec, reflect.TypeOf(dst).Elem()); err != nil {
+		return err
+	}
+	if _, err := dec.Token(); err != io.EOF {
+		return fmt.Errorf("trailing recovery data: %v", err)
+	}
+	return json.Unmarshal(data, dst)
+}
+
+func checkRecoveryValue(dec *json.Decoder, typ reflect.Type) error {
+	token, err := dec.Token()
+	if err != nil {
+		return err
+	}
+	if token == nil {
+		if typ.Kind() == reflect.Slice {
+			return nil
+		}
+		return fmt.Errorf("null recovery %s", typ)
+	}
+	switch typ.Kind() {
+	case reflect.Struct:
+		if token != json.Delim('{') {
+			return fmt.Errorf("expected recovery object")
+		}
+		fields := map[string]reflect.Type{}
+		for i := 0; i < typ.NumField(); i++ {
+			f := typ.Field(i)
+			name := strings.Split(f.Tag.Get("json"), ",")[0]
+			if name != "" && name != "-" {
+				fields[name] = f.Type
+			}
+		}
+		seen := map[string]bool{}
+		for dec.More() {
+			key, err := dec.Token()
+			if err != nil {
+				return err
+			}
+			name, ok := key.(string)
+			if !ok {
+				return fmt.Errorf("invalid recovery key")
+			}
+			ft, known := fields[name]
+			if !known || seen[name] {
+				return fmt.Errorf("unknown or duplicate recovery field %q", name)
+			}
+			seen[name] = true
+			if err := checkRecoveryValue(dec, ft); err != nil {
+				return fmt.Errorf("%s: %w", name, err)
+			}
+		}
+		_, err = dec.Token()
+		return err
+	case reflect.Slice:
+		if token != json.Delim('[') {
+			return fmt.Errorf("expected recovery array")
+		}
+		for dec.More() {
+			if err := checkRecoveryValue(dec, typ.Elem()); err != nil {
+				return err
+			}
+		}
+		_, err = dec.Token()
+		return err
+	case reflect.String:
+		if _, ok := token.(string); !ok {
+			return fmt.Errorf("expected recovery string")
+		}
+	case reflect.Bool:
+		if _, ok := token.(bool); !ok {
+			return fmt.Errorf("expected recovery boolean")
+		}
+	default:
+		return fmt.Errorf("unsupported recovery type %s", typ)
+	}
+	return nil
+}
+
+func validDigest(value string, sizes ...int) bool {
+	for _, size := range sizes {
+		if len(value) == size {
+			_, err := hex.DecodeString(value)
+			return err == nil && value == strings.ToLower(value)
+		}
+	}
+	return false
+}
+
+// A State from the previous update may coexist with a newly written build
+// marker. Read it strictly, and distinguish absent from damaged evidence.
+func recoveryState(root string) (State, bool, error) {
+	var st State
+	data, err := os.ReadFile(statePath(root))
+	if os.IsNotExist(err) {
+		return st, false, nil
+	}
+	if err != nil {
+		return st, false, err
+	}
+	if err := decodeRecoveryJSON(data, &st); err != nil {
+		return st, true, err
+	}
+	return st, true, validateRecoveryState(st)
+}
+
+func validateRecoveryState(st State) error {
+	if !validDigest(st.PreviousCommit, 40, 64) || !validDigest(st.UpdatedCommit, 40, 64) {
+		return fmt.Errorf("invalid state commits")
+	}
+	for _, hash := range []string{st.BinarySHA256, st.PreviousBinarySHA256} {
+		if hash != "" && !validDigest(hash, 64) {
+			return fmt.Errorf("invalid state binary hash")
+		}
+	}
+	if st.PreviousBinaryAbsent && st.BinaryCommit == st.PreviousCommit && st.BinarySHA256 != "" {
+		return fmt.Errorf("absent previous binary has a live hash")
+	}
+	if st.PreviousBinaryAbsent && st.PreviousBinarySHA256 != "" {
+		return fmt.Errorf("state contradicts binary absence")
+	}
+	return nil
+}
+
+func validateBuildEvidence(root string, p buildPendingState) error {
+	if !validDigest(p.Commit, 40, 64) || (p.PreviousCommit != "" && (!validDigest(p.PreviousCommit, 40, 64) || p.PreviousCommit == p.Commit)) {
+		return fmt.Errorf("invalid build commits")
+	}
+	if p.PreviousBinaryAbsent == (p.PreviousBinarySHA256 != "") {
+		return fmt.Errorf("build record must prove previous binary hash or absence")
+	}
+	if p.PreviousBinarySHA256 != "" && !validDigest(p.PreviousBinarySHA256, 64) {
+		return fmt.Errorf("invalid previous binary hash")
+	}
+	if p.BinarySHA256 != "" && !validDigest(p.BinarySHA256, 64) {
+		return fmt.Errorf("invalid built binary hash")
+	}
+	st, present, err := recoveryState(root)
+	if err != nil || !present {
+		return err
+	}
+	if st.BinaryCommit != "" && st.BinaryCommit != st.PreviousCommit && st.BinaryCommit != st.UpdatedCommit {
+		return fmt.Errorf("state binary commit is unrelated")
+	}
+	switch {
+	case st.UpdatedCommit == p.Commit:
+		if st.PreviousCommit != p.PreviousCommit || st.PreviousBinarySHA256 != p.PreviousBinarySHA256 || st.PreviousBinaryAbsent != p.PreviousBinaryAbsent {
+			return fmt.Errorf("build record contradicts rollback state")
+		}
+		if st.BinaryCommit == p.PreviousCommit && st.BinarySHA256 != p.PreviousBinarySHA256 {
+			return fmt.Errorf("pre-build state contradicts previous binary hash")
+		}
+		if st.BinaryCommit == p.Commit && (p.BinarySHA256 == "" || st.BinarySHA256 != p.BinarySHA256) {
+			return fmt.Errorf("completed build lacks matching recovery hash")
+		}
+	case st.UpdatedCommit == p.PreviousCommit:
+		if st.BinaryCommit != st.UpdatedCommit || st.BinarySHA256 == "" || st.BinarySHA256 != p.PreviousBinarySHA256 || p.PreviousBinaryAbsent {
+			return fmt.Errorf("previous update does not prove the current binary")
+		}
+	default:
+		return fmt.Errorf("build record belongs to a different update")
+	}
+	return nil
+}
+
+func validateBuildFiles(bin string, p buildPendingState) error {
+	if p.Legacy {
+		return nil
+	} // The legacy path separately proves identity from State/VCS.
+	live, err := fileSHA256(bin)
+	if err == nil && p.BinarySHA256 != "" && live == p.BinarySHA256 {
+		if !p.PreviousBinaryAbsent {
+			previous, e := fileSHA256(bin + ".prev")
+			if e != nil || previous != p.PreviousBinarySHA256 {
+				return fmt.Errorf("completed swap has no matching rollback binary")
+			}
+		}
+		return nil
+	}
+	if p.PreviousBinaryAbsent {
+		if !os.IsNotExist(err) {
+			return fmt.Errorf("binary exists despite recorded absence")
+		}
+		return nil
+	}
+	if err == nil && live == p.PreviousBinarySHA256 {
+		return nil
+	}
+	// installBinary can crash between moving live to .prev and installing staged.
+	if os.IsNotExist(err) && p.BinarySHA256 != "" {
+		previous, e := fileSHA256(bin + ".prev")
+		if e == nil && previous == p.PreviousBinarySHA256 {
+			return nil
+		}
+	}
+	return fmt.Errorf("live binary does not match build recovery evidence")
+}
+
+func validateRollbackEvidence(root string, p rollbackPendingState) error {
+	st := p.State
+	if err := validateRecoveryState(st); err != nil {
+		return err
+	}
+	if !validDigest(st.PreviousCommit, 40, 64) || !validDigest(st.UpdatedCommit, 40, 64) || st.PreviousCommit == st.UpdatedCommit {
+		return fmt.Errorf("invalid rollback commits")
+	}
+	if p.LiveSHA256 != "" && !validDigest(p.LiveSHA256, 64) {
+		return fmt.Errorf("invalid live hash")
+	}
+	if p.RestoreBinary {
+		if !validDigest(p.LiveSHA256, 64) || !validDigest(p.PreviousSHA256, 64) || st.PreviousBinaryAbsent {
+			return fmt.Errorf("rollback lacks binary evidence")
+		}
+		if st.BinaryCommit != "" && st.BinaryCommit != st.UpdatedCommit {
+			return fmt.Errorf("rollback binary decision contradicts state")
+		}
+		if st.PreviousBinarySHA256 != "" && p.PreviousSHA256 != st.PreviousBinarySHA256 {
+			return fmt.Errorf("rollback previous hash contradicts state")
+		}
+	} else {
+		if st.PreviousBinaryAbsent && p.LiveSHA256 != "" {
+			return fmt.Errorf("rollback absence contradicts live hash")
+		}
+		if p.LiveSHA256 == "" && !st.PreviousBinaryAbsent {
+			return fmt.Errorf("rollback lacks unchanged binary evidence")
+		}
+		if p.PreviousSHA256 != "" || st.BinaryCommit != st.PreviousCommit {
+			return fmt.Errorf("rollback cannot skip binary restoration")
+		}
+	}
+	if st.BinarySHA256 != "" && p.LiveSHA256 != st.BinarySHA256 {
+		return fmt.Errorf("rollback live hash contradicts state")
+	}
+	disk, present, err := recoveryState(root)
+	if err != nil {
+		return err
+	}
+	if present && disk != st {
+		return fmt.Errorf("rollback journal contradicts persisted state")
+	}
+	return nil
+}
diff --git a/internal/update/recovery_json_test.go b/internal/update/recovery_json_test.go
new file mode 100644
index 00000000..152fbd4c
--- /dev/null
+++ b/internal/update/recovery_json_test.go
@@ -0,0 +1,74 @@
+package update
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+)
+
+func TestRecoveryJSONRefusesAmbiguousFields(t *testing.T) {
+	for _, data := range []string{
+		`null`, `[]`, `{} {}`, `{"commit":null}`, `{"commit":123}`,
+		`{"commit":"a","commit":"a"}`, `{"commit":"a","commit":"b"}`,
+		`{"Commit":"a"}`, `{"unknown":true}`, `{"previous_binary_absent":"true"}`,
+		`{"previous_binary_absent":null}`, `{"kept_content":[null]}`,
+	} {
+		t.Run(data, func(t *testing.T) {
+			var p buildPendingState
+			if err := decodeRecoveryJSON([]byte(data), &p); err == nil {
+				t.Fatal("ambiguous JSON accepted")
+			}
+		})
+	}
+	// Duplicate nested state fields must not overwrite the evidence either.
+	var rollback rollbackPendingState
+	if err := decodeRecoveryJSON([]byte(`{"state":{"binary_sha256":"a","binary_sha256":"b"}}`), &rollback); err == nil {
+		t.Fatal("duplicate nested evidence accepted")
+	}
+}
+
+func TestBuildEvidenceRequiresOldBinaryProof(t *testing.T) {
+	for _, p := range []buildPendingState{
+		{Commit: strings.Repeat("a", 40)},
+		{Commit: strings.Repeat("a", 40), PreviousBinarySHA256: ""},
+		{Commit: strings.Repeat("a", 40), PreviousBinarySHA256: "bad"},
+		{Commit: strings.Repeat("a", 40), PreviousBinarySHA256: strings.Repeat("b", 64), PreviousBinaryAbsent: true},
+		{Commit: strings.Repeat("a", 40), PreviousBinaryAbsent: true, BinarySHA256: "bad"},
+	} {
+		if err := validateBuildEvidence(t.TempDir(), p); err == nil {
+			t.Fatalf("incomplete evidence accepted: %+v", p)
+		}
+	}
+	for _, p := range []buildPendingState{
+		{Commit: strings.Repeat("a", 40), PreviousBinaryAbsent: true},
+		{Commit: strings.Repeat("a", 40), PreviousBinarySHA256: strings.Repeat("b", 64)},
+	} {
+		data, _ := json.Marshal(p)
+		var decoded buildPendingState
+		if err := decodeRecoveryJSON(data, &decoded); err != nil {
+			t.Fatal(err)
+		}
+		if err := validateBuildEvidence(t.TempDir(), decoded); err != nil {
+			t.Fatal(err)
+		}
+	}
+}
+
+func TestRollbackEvidenceWithoutDiskState(t *testing.T) {
+	st := State{PreviousCommit: strings.Repeat("a", 40), UpdatedCommit: strings.Repeat("b", 40), BinaryCommit: strings.Repeat("a", 40), PreviousBinaryAbsent: true}
+	p := rollbackPendingState{State: st}
+	if err := validateRollbackEvidence(t.TempDir(), p); err != nil {
+		t.Fatal(err)
+	}
+	for _, hash := range []string{"bad", strings.Repeat("c", 64)} {
+		p.State.PreviousBinarySHA256 = hash
+		if err := validateRollbackEvidence(t.TempDir(), p); err == nil {
+			t.Fatal("missing disk state bypassed embedded state validation")
+		}
+	}
+	p.State = st
+	p.State.PreviousBinaryAbsent = false
+	if err := validateRollbackEvidence(t.TempDir(), p); err == nil {
+		t.Fatal("missing live evidence accepted without binary absence")
+	}
+}
diff --git a/internal/update/recovery_phase_test.go b/internal/update/recovery_phase_test.go
new file mode 100644
index 00000000..899ccb2c
--- /dev/null
+++ b/internal/update/recovery_phase_test.go
@@ -0,0 +1,143 @@
+package update
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestRollbackRecoveryRequiresActualBinaryAbsence(t *testing.T) {
+	requireGit(t)
+	tr := newTree(t)
+	before := mustGit(t, tr.install, "rev-parse", "HEAD")
+	tr.upstreamCommit(t, "next", map[string]string{"review.go": "package review\n"})
+	mustGit(t, tr.install, "fetch", "origin")
+	target := mustGit(t, tr.install, "rev-parse", "origin/main")
+	bin := filepath.Join(tr.install, Binary)
+	writeFile(t, bin, "unrelated live binary")
+	p := rollbackPendingState{State: State{PreviousCommit: before, UpdatedCommit: target, BinaryCommit: before, PreviousBinaryAbsent: true}, RestoreBinary: false}
+	if err := writeRollbackPending(tr.install, p); err != nil {
+		t.Fatal(err)
+	}
+	_, err := Rollback(context.Background(), buildOpts(tr))
+	t.Logf("error=%v live=%q marker_exists=%v", err, readFile(t, bin), fileExists(filepath.Join(tr.install, rollbackPendingFile)))
+	if err == nil || !fileExists(filepath.Join(tr.install, rollbackPendingFile)) {
+		t.Fatal("contradictory absence evidence authorized cleanup")
+	}
+}
+func TestBuildRecoveryBeforeMergeRequiresFileProof(t *testing.T) {
+	requireGit(t)
+	tr := newTree(t)
+	before := mustGit(t, tr.install, "rev-parse", "HEAD")
+	bin := filepath.Join(tr.install, Binary)
+	writeFile(t, bin, "old binary")
+	oldHash, _ := fileSHA256(bin)
+	tr.upstreamCommit(t, "next", map[string]string{"review.go": "package review\n"})
+	mustGit(t, tr.install, "fetch", "origin")
+	target := mustGit(t, tr.install, "rev-parse", "origin/main")
+	p := buildPendingState{Commit: target, PreviousCommit: before, PreviousBinarySHA256: oldHash}
+	if err := writeBuildPending(tr.install, p); err != nil {
+		t.Fatal(err)
+	}
+	writeFile(t, bin, "unrelated live binary")
+	err := finishPendingBuild(context.Background(), &Snapshot{Root: tr.install}, buildOpts(tr), &Result{}, func(string, string) {})
+	_, statErr := os.Stat(buildPendingPath(tr.install))
+	t.Logf("error=%v marker_stat=%v", err, statErr)
+	if err == nil || os.IsNotExist(statErr) {
+		t.Fatal("mismatching binary evidence authorized marker deletion")
+	}
+}
+
+func TestLegacyRecoveryRejectsMalformedState(t *testing.T) {
+	requireGit(t)
+	tr := newTree(t)
+	scriptFakeGo(t)
+	bin := filepath.Join(tr.install, Binary)
+	writeFile(t, bin, "old binary")
+	tr.upstreamCommit(t, "next", map[string]string{"review.go": "package review\n"})
+	if _, err := Apply(context.Background(), buildOpts(tr), nil); err != nil {
+		t.Fatal(err)
+	}
+	state := readFile(t, statePath(tr.install))
+	state = state[:len(state)-2] + ",\"binary_sha256\":null}"
+	writeFile(t, statePath(tr.install), state)
+	writeFile(t, buildPendingPath(tr.install), "source is ahead of the binary")
+	builds := 0
+	_, err := Apply(context.Background(), buildOpts(tr), func(s Step) {
+		if s.Phase == "build" {
+			builds++
+		}
+	})
+	t.Logf("error=%v builds=%d marker_exists=%v", err, builds, fileExists(buildPendingPath(tr.install)))
+	if err == nil || builds != 0 || !fileExists(buildPendingPath(tr.install)) {
+		t.Fatal("legacy marker authorized mutation with malformed state")
+	}
+}
+
+func TestFreshRollbackRejectsMalformedState(t *testing.T) {
+	requireGit(t)
+	tr := newTree(t)
+	scriptFakeGo(t)
+	bin := filepath.Join(tr.install, Binary)
+	writeFile(t, bin, "old binary")
+	tr.upstreamCommit(t, "next", map[string]string{"review.go": "package review\n"})
+	if _, err := Apply(context.Background(), buildOpts(tr), nil); err != nil {
+		t.Fatal(err)
+	}
+	writeFile(t, bin+".prev", "unrelated backup")
+	wrong, _ := fileSHA256(bin + ".prev")
+	state := readFile(t, statePath(tr.install))
+	state = state[:len(state)-2] + fmt.Sprintf(",\"previous_binary_sha256\":%q}", wrong)
+	writeFile(t, statePath(tr.install), state)
+	_, err := Rollback(context.Background(), buildOpts(tr))
+	t.Logf("error=%v binary=%q state_exists=%v", err, readFile(t, bin), fileExists(statePath(tr.install)))
+	if err == nil || !fileExists(statePath(tr.install)) {
+		t.Fatal("malformed state authorized wrong rollback")
+	}
+}
+
+func TestRollbackAbsenceCannotHaveLiveHash(t *testing.T) {
+	requireGit(t)
+	tr := newTree(t)
+	before := mustGit(t, tr.install, "rev-parse", "HEAD")
+	tr.upstreamCommit(t, "next", map[string]string{"review.go": "package review\n"})
+	mustGit(t, tr.install, "fetch", "origin")
+	target := mustGit(t, tr.install, "rev-parse", "origin/main")
+	bin := filepath.Join(tr.install, Binary)
+	writeFile(t, bin, "unrelated live binary")
+	hash, _ := fileSHA256(bin)
+	p := rollbackPendingState{State: State{PreviousCommit: before, UpdatedCommit: target, BinaryCommit: before, PreviousBinaryAbsent: true, BinarySHA256: hash}, LiveSHA256: hash, RestoreBinary: false}
+	if err := writeRollbackPending(tr.install, p); err != nil {
+		t.Fatal(err)
+	}
+	_, err := Rollback(context.Background(), buildOpts(tr))
+	t.Logf("error=%v marker_exists=%v", err, fileExists(filepath.Join(tr.install, rollbackPendingFile)))
+	if err == nil || !fileExists(filepath.Join(tr.install, rollbackPendingFile)) {
+		t.Fatal("absent binary with a hash authorized cleanup")
+	}
+}
+
+func TestBuildBeforeMergeRejectsPostSwap(t *testing.T) {
+	requireGit(t)
+	tr := newTree(t)
+	scriptFakeGo(t)
+	bin := filepath.Join(tr.install, Binary)
+	writeFile(t, bin, "old binary")
+	tr.upstreamCommit(t, "next", map[string]string{"review.go": "package review\n"})
+	if _, err := Apply(context.Background(), buildOpts(tr), nil); err != nil {
+		t.Fatal(err)
+	}
+	st, _ := readState(tr.install)
+	p := buildPendingState{Commit: st.UpdatedCommit, PreviousCommit: st.PreviousCommit, BinarySHA256: st.BinarySHA256, PreviousBinarySHA256: st.PreviousBinarySHA256}
+	if err := writeBuildPending(tr.install, p); err != nil {
+		t.Fatal(err)
+	}
+	mustGit(t, tr.install, "reset", "--hard", st.PreviousCommit)
+	err := finishPendingBuild(context.Background(), &Snapshot{Root: tr.install}, buildOpts(tr), &Result{}, func(string, string) {})
+	t.Logf("error=%v marker_exists=%v", err, fileExists(buildPendingPath(tr.install)))
+	if err == nil || !fileExists(buildPendingPath(tr.install)) {
+		t.Fatal("post-swap files with pre-merge HEAD authorized cleanup")
+	}
+}
diff --git a/internal/update/recovery_regression_test.go b/internal/update/recovery_regression_test.go
new file mode 100644
index 00000000..cb7a783b
--- /dev/null
+++ b/internal/update/recovery_regression_test.go
@@ -0,0 +1,109 @@
+package update
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestBuildRecoveryRejectsAmbiguousEvidence(t *testing.T) {
+	for _, kind := range []string{"valid_residual", "missing_hashes", "null_hashes", "conflicting_duplicate", "contradictory_prior_hash"} {
+		t.Run(kind, func(t *testing.T) {
+			requireGit(t)
+			tr := newTree(t)
+			scriptFakeGo(t)
+			bin := filepath.Join(tr.install, Binary)
+			writeFile(t, bin, "original binary")
+			before := mustGit(t, tr.install, "rev-parse", "HEAD")
+			tr.upstreamCommit(t, "release", map[string]string{"internal_service.go": "package service\nconst Version = \"2\"\n"})
+			if _, err := Apply(context.Background(), buildOpts(tr), nil); err != nil {
+				t.Fatal(err)
+			}
+			target := mustGit(t, tr.install, "rev-parse", "HEAD")
+			st, _ := readState(tr.install)
+			var marker string
+			switch kind {
+			case "valid_residual":
+				marker = fmt.Sprintf(`{"commit":%q,"previous_commit":%q,"binary_sha256":%q,"previous_binary_sha256":%q}`, target, before, st.BinarySHA256, st.PreviousBinarySHA256)
+			case "missing_hashes":
+				marker = fmt.Sprintf(`{"commit":%q}`, target)
+			case "null_hashes":
+				marker = fmt.Sprintf(`{"commit":%q,"binary_sha256":null,"previous_binary_sha256":null}`, target)
+			case "conflicting_duplicate":
+				marker = fmt.Sprintf(`{"commit":%q,"previous_commit":%q,"previous_binary_sha256":%q,"previous_binary_sha256":%q}`, target, before, st.PreviousBinarySHA256, st.BinarySHA256)
+			case "contradictory_prior_hash":
+				marker = fmt.Sprintf(`{"commit":%q,"previous_commit":%q,"previous_binary_sha256":%q}`, target, before, st.BinarySHA256)
+			}
+			if err := os.WriteFile(buildPendingPath(tr.install), []byte(marker), 0644); err != nil {
+				t.Fatal(err)
+			}
+			liveBefore := readFile(t, bin)
+			stateBefore := readFile(t, statePath(tr.install))
+			builds := 0
+			res, err := Apply(context.Background(), buildOpts(tr), func(s Step) {
+				if s.Phase == "build" {
+					builds++
+				}
+			})
+			t.Logf("recovery builds=%d error=%v result=%+v", builds, err, res)
+			gotPrev := readFile(t, bin+".prev")
+			if kind == "valid_residual" {
+				if builds != 0 || gotPrev != "original binary" || err != nil {
+					t.Fatalf("valid residual replay: builds=%d prev=%q err=%v", builds, gotPrev, err)
+				}
+				return
+			}
+			if err != nil && gotPrev == "original binary" && builds == 0 {
+				if readFile(t, bin) != liveBefore || readFile(t, statePath(tr.install)) != stateBefore || readFile(t, buildPendingPath(tr.install)) != marker {
+					t.Fatal("refusal changed live binary or recovery evidence")
+				}
+				return
+			}
+			if _, rbErr := Rollback(context.Background(), buildOpts(tr)); rbErr != nil {
+				t.Logf("rollback error=%v", rbErr)
+			} else {
+				t.Logf("rollback HEAD=%s binary=%q", mustGit(t, tr.install, "rev-parse", "HEAD"), readFile(t, bin))
+			}
+			t.Fatalf("unsafe malformed recovery: builds=%d error=%v previous binary=%q (wanted refusal before build/swap; original binary preserved)", builds, err, gotPrev)
+		})
+	}
+}
+
+func TestBuildRecoveryBetweenBinaryRenames(t *testing.T) {
+	requireGit(t)
+	tr := newTree(t)
+	scriptFakeGo(t)
+	bin := filepath.Join(tr.install, Binary)
+	writeFile(t, bin, "original binary")
+	tr.upstreamCommit(t, "second", map[string]string{"run.sh": "new script\n"})
+	if _, err := Apply(context.Background(), buildOpts(tr), nil); err != nil {
+		t.Fatal(err)
+	}
+	st, _ := readState(tr.install)
+	pending := buildPendingState{Commit: st.UpdatedCommit, PreviousCommit: st.PreviousCommit, BinarySHA256: st.BinarySHA256, PreviousBinarySHA256: st.PreviousBinarySHA256}
+	st.BinaryCommit = st.PreviousCommit
+	st.BinarySHA256 = st.PreviousBinarySHA256
+	if err := writeState(tr.install, st); err != nil {
+		t.Fatal(err)
+	}
+	if err := writeBuildPending(tr.install, pending); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Remove(bin); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := Apply(context.Background(), buildOpts(tr), nil); err != nil {
+		t.Fatal(err)
+	}
+	if readFile(t, bin+".prev") != "original binary" {
+		t.Fatal("interrupted swap lost previous binary")
+	}
+	if _, err := Rollback(context.Background(), buildOpts(tr)); err != nil {
+		t.Fatal(err)
+	}
+	if readFile(t, bin) != "original binary" {
+		t.Fatal("rollback no longer restores original binary")
+	}
+}
diff --git a/internal/update/rollback_evidence_test.go b/internal/update/rollback_evidence_test.go
new file mode 100644
index 00000000..9f8df2ef
--- /dev/null
+++ b/internal/update/rollback_evidence_test.go
@@ -0,0 +1,103 @@
+package update
+
+import (
+	"context"
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestRollbackRecoveryRejectsAmbiguousEvidence(t *testing.T) {
+	for _, variant := range []string{"valid", "missing_restore_binary", "missing_live_hash", "contradictory_previous_hash", "duplicate_restore_binary"} {
+		t.Run(variant, func(t *testing.T) {
+			requireGit(t)
+			tr := newTree(t)
+			scriptFakeGo(t)
+			bin := filepath.Join(tr.install, Binary)
+			writeFile(t, bin, "original binary")
+			tr.upstreamCommit(t, "second", map[string]string{"run.sh": "new script\n"})
+			if _, err := Apply(context.Background(), buildOpts(tr), nil); err != nil {
+				t.Fatal(err)
+			}
+			st, _ := readState(tr.install)
+			live := readFile(t, bin)
+			liveHash, _ := fileSHA256(bin)
+			previousHash, _ := fileSHA256(bin + ".prev")
+			pending := rollbackPendingState{State: st, RestoreBinary: true, LiveSHA256: liveHash, PreviousSHA256: previousHash}
+			encoded, _ := json.Marshal(pending)
+			var fields map[string]interface{}
+			_ = json.Unmarshal(encoded, &fields)
+			switch variant {
+			case "missing_restore_binary":
+				delete(fields, "restore_binary")
+			case "missing_live_hash":
+				delete(fields, "live_sha256")
+			case "contradictory_previous_hash":
+				writeFile(t, bin+".prev", "unrelated binary")
+				wrongHash, _ := fileSHA256(bin + ".prev")
+				fields["previous_sha256"] = wrongHash
+			}
+			encoded, _ = json.Marshal(fields)
+			if variant == "duplicate_restore_binary" {
+				encoded = append(encoded[:len(encoded)-1], []byte(",\"restore_binary\":false}")...)
+			}
+			if err := os.WriteFile(filepath.Join(tr.install, rollbackPendingFile), encoded, 0600); err != nil {
+				t.Fatal(err)
+			}
+			mustGit(t, tr.install, "reset", "--hard", st.PreviousCommit)
+			_, err := Rollback(context.Background(), buildOpts(tr))
+			if variant == "valid" {
+				if err != nil {
+					t.Fatal(err)
+				}
+				if got := readFile(t, bin); got != "original binary" {
+					t.Fatalf("valid rollback did not restore binary: %q", got)
+				}
+				return
+			}
+			if err == nil {
+				t.Errorf("malformed/contradictory marker authorized recovery, live before=%q after=%q; state exists=%v marker exists=%v", live, readFile(t, bin), fileExists(statePath(tr.install)), fileExists(filepath.Join(tr.install, rollbackPendingFile)))
+			}
+			if got := readFile(t, bin); got != live {
+				t.Errorf("invalid evidence mutated binary: %q => %q", live, got)
+			}
+			if !fileExists(statePath(tr.install)) || !fileExists(filepath.Join(tr.install, rollbackPendingFile)) {
+				t.Error("invalid evidence deleted recovery records")
+			}
+		})
+	}
+}
+
+func TestRollbackRecoveryAfterStateCleanup(t *testing.T) {
+	requireGit(t)
+	tr := newTree(t)
+	scriptFakeGo(t)
+	bin := filepath.Join(tr.install, Binary)
+	writeFile(t, bin, "original binary")
+	tr.upstreamCommit(t, "second", map[string]string{"run.sh": "new script\n"})
+	if _, err := Apply(context.Background(), buildOpts(tr), nil); err != nil {
+		t.Fatal(err)
+	}
+	st, _ := readState(tr.install)
+	pending := rollbackPendingState{State: st, RestoreBinary: true, LiveSHA256: st.BinarySHA256, PreviousSHA256: st.PreviousBinarySHA256}
+	if err := writeRollbackPending(tr.install, pending); err != nil {
+		t.Fatal(err)
+	}
+	mustGit(t, tr.install, "reset", "--hard", st.PreviousCommit)
+	if err := restorePrevBinary(bin); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Remove(statePath(tr.install)); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := Rollback(context.Background(), buildOpts(tr)); err != nil {
+		t.Fatal(err)
+	}
+	if readFile(t, bin) != "original binary" {
+		t.Fatal("cleanup retry changed restored binary")
+	}
+	if fileExists(filepath.Join(tr.install, rollbackPendingFile)) {
+		t.Fatal("cleanup retry left journal")
+	}
+}
diff --git a/internal/update/rollback_pending.go b/internal/update/rollback_pending.go
index 228d89c8..656893e2 100644
--- a/internal/update/rollback_pending.go
+++ b/internal/update/rollback_pending.go
@@ -29,11 +29,16 @@ func readRollbackPending(root string) (*rollbackPendingState, error) {
 		return nil, err
 	}
 	var pending rollbackPendingState
-	if err := json.Unmarshal(data, &pending); err != nil {
+	if err := decodeRecoveryJSON(data, &pending); err != nil {
 		return nil, err
 	}
-	if pending.State.PreviousCommit == "" || pending.State.UpdatedCommit == "" {
-		return nil, fmt.Errorf("回滚恢复记录缺少提交")
+	var fields map[string]json.RawMessage
+	_ = json.Unmarshal(data, &fields)
+	if _, ok := fields["restore_binary"]; !ok {
+		return nil, fmt.Errorf("回滚恢复记录缺少二进制恢复决策")
+	}
+	if err := validateRollbackEvidence(root, pending); err != nil {
+		return nil, err
 	}
 	return &pending, nil
 }
@@ -58,6 +63,11 @@ func finishRollback(ctx context.Context, opts Options, pending rollbackPendingSt
 		return nil, err
 	}
 	bin := filepath.Join(root, opts.binaryName())
+	if !pending.RestoreBinary && pending.LiveSHA256 == "" {
+		if _, err := os.Lstat(bin); !os.IsNotExist(err) {
+			return nil, &Error{Reason: "binary_changed", Message: "恢复记录要求二进制不存在，但现场不匹配；已保留记录"}
+		}
+	}
 	if pending.RestoreBinary {
 		current, currentErr := fileSHA256(bin)
 		if currentErr != nil || current != pending.PreviousSHA256 {