diff --git a/admin/handler/api/client_api.go b/admin/handler/api/client_api.go
index c4195ef..f3fba90 100644
--- a/admin/handler/api/client_api.go
+++ b/admin/handler/api/client_api.go
@@ -3,7 +3,7 @@
 // **权威契约在 Client 那边**：docs/client/04-admin-api-contract.md。
 // 本包只是实现，两边说法不一致时以 Client 契约为准，要改先走工单。
 //
-// 一共只有三个接口，**不得新增"让 Client 查询状态"类接口**，
+// 接口都是一次性命令，**不得新增"让 Client 查询状态"类接口**，
 // 也不得加回租约和心跳，理由见 docs/admin/04-client-api.md §1。
 package api
 
@@ -23,12 +23,14 @@ import (
 
 // Handler 持有接口共用的依赖。
 type Handler struct {
-	db *sql.DB
+	db        *sql.DB
+	aiSecrets service.AISecretStore
+	aiPolicy  service.AIEndpointPolicy
 }
 
-// Register 挂上三个接口。
-func Register(r *gin.Engine, db *sql.DB) {
-	h := &Handler{db: db}
+// Register 挂上 Client 命令接口。
+func Register(r *gin.Engine, db *sql.DB, aiSecrets service.AISecretStore, aiPolicy service.AIEndpointPolicy) {
+	h := &Handler{db: db, aiSecrets: aiSecrets, aiPolicy: aiPolicy}
 
 	g := r.Group("/api/v1/client")
 	{
@@ -38,6 +40,7 @@ func Register(r *gin.Engine, db *sql.DB) {
 		g.POST("/tasks/claim", h.Claim)
 		g.POST("/tasks/:task_id/result", h.SubmitResult)
 		g.POST("/tasks/:task_id/failure", h.SubmitFailure)
+		g.POST("/tasks/:task_id/spec-resolution", h.ResolvePurchaseSpec)
 	}
 }
 
@@ -203,6 +206,62 @@ func (h *Handler) SubmitFailure(c *gin.Context) {
 	h.handleSubmit(c, service.SubmitFailure, "task_failure_received")
 }
 
+// ResolvePurchaseSpec 接收 Client 当前 PDD 页面上的可购买尺码快照。
+// 这是一次性决策命令，不查询或修改任务状态，也不会绕过 Client 的下单复核门禁。
+func (h *Handler) ResolvePurchaseSpec(c *gin.Context) {
+	taskID := c.Param("task_id")
+	clientID := c.GetHeader("X-Client-Id")
+	if clientID == "" {
+		apiError(c, http.StatusBadRequest, "MISSING_CLIENT_ID", "缺少 X-Client-Id 请求头", false)
+		return
+	}
+	idempotencyKey := c.GetHeader("Idempotency-Key")
+	if idempotencyKey == "" {
+		apiError(c, http.StatusBadRequest, "MISSING_IDEMPOTENCY_KEY", "缺少 Idempotency-Key 请求头", false)
+		return
+	}
+
+	c.Request.Body = http.MaxBytesReader(c.Writer, c.Request.Body, service.MaxPurchaseSpecResolutionBodyBytes)
+	rawBody, err := io.ReadAll(c.Request.Body)
+	if err != nil {
+		apiError(c, http.StatusBadRequest, "INVALID_BODY", "请求体不是合法 JSON 或超过 64 KiB", false)
+		return
+	}
+	responseJSON, err := service.ResolvePurchaseSpec(c.Request.Context(), h.db, h.aiSecrets, h.aiPolicy,
+		taskID, clientID, idempotencyKey, rawBody)
+	switch {
+	case err == nil:
+		log.Printf("purchase_spec_resolved client_id=%s task_id=%s", clientID, taskID)
+		c.Data(http.StatusOK, "application/json; charset=utf-8", []byte(responseJSON))
+	case errors.Is(err, service.ErrInvalidSpecResolutionBody):
+		apiError(c, http.StatusBadRequest, "INVALID_BODY", "请求体不是合法 JSON 或超过 64 KiB", false)
+	case errors.Is(err, service.ErrInvalidSpecResolutionSchema):
+		apiError(c, http.StatusBadRequest, "INVALID_SPEC_RESOLUTION_SCHEMA", "不支持的规格解析 schema_version", false)
+	case errors.Is(err, service.ErrInvalidSpecResolutionRequest):
+		apiError(c, http.StatusUnprocessableEntity, "INVALID_SPEC_RESOLUTION_REQUEST", "规格解析字段或任务目标规格无效", false)
+	case errors.Is(err, service.ErrSpecResolutionHashMismatch):
+		apiError(c, http.StatusUnprocessableEntity, "SPEC_RESOLUTION_HASH_MISMATCH", "候选快照哈希或幂等键不一致", false)
+	case errors.Is(err, service.ErrTaskNotFound):
+		apiError(c, http.StatusNotFound, "TASK_NOT_FOUND", "任务不存在", false)
+	case errors.Is(err, service.ErrTaskNotPurchase):
+		apiError(c, http.StatusUnprocessableEntity, "TASK_NOT_PURCHASE", "任务不是采购任务", false)
+	case errors.Is(err, service.ErrTaskVersionConflict):
+		apiError(c, http.StatusConflict, "TASK_VERSION_CONFLICT", "任务版本已变化", false)
+	case errors.Is(err, service.ErrPDDGoodsMismatch):
+		apiError(c, http.StatusUnprocessableEntity, "PDD_GOODS_MISMATCH", "PDD 商品与任务不一致", false)
+	case errors.Is(err, service.ErrNeverClaimed):
+		apiError(c, http.StatusForbidden, "TASK_NOT_CLAIMED_BY_CLIENT", "该 Client 从未领取过此任务", false)
+	case errors.Is(err, service.ErrIdempotencyConflict):
+		apiError(c, http.StatusConflict, "IDEMPOTENCY_CONFLICT", "相同幂等身份提交了不同内容", false)
+	case errors.Is(err, service.ErrSpecResolutionUnavailable):
+		log.Printf("purchase_spec_unavailable client_id=%s task_id=%s err=%v", clientID, taskID, err)
+		apiError(c, http.StatusServiceUnavailable, "SPEC_RESOLUTION_UNAVAILABLE", "规格解析服务暂不可用，请有限重试原请求", true)
+	default:
+		log.Printf("purchase_spec_failed client_id=%s task_id=%s err=%v", clientID, taskID, err)
+		apiError(c, http.StatusInternalServerError, "SPEC_RESOLUTION_FAILED", "规格解析失败，请稍后重试", true)
+	}
+}
+
 // submitFunc 是两个提交接口共用的处理函数形状。
 type submitFunc func(db *sql.DB, taskID, clientID, idemKey string, rawBody []byte) (string, error)
 
diff --git a/admin/handler/api/client_api_test.go b/admin/handler/api/client_api_test.go
index b52781e..fffba37 100644
--- a/admin/handler/api/client_api_test.go
+++ b/admin/handler/api/client_api_test.go
@@ -1,9 +1,16 @@
 package api
 
 import (
+	"bytes"
+	"net/http"
+	"net/http/httptest"
+	"strings"
 	"testing"
 
+	"github.com/gin-gonic/gin"
+
 	"cmautobuy/admin/model"
+	"cmautobuy/admin/service"
 )
 
 func TestTaskPayload_包含不可变执行模式(t *testing.T) {
@@ -12,3 +19,20 @@ func TestTaskPayload_包含不可变执行模式(t *testing.T) {
 		t.Fatalf("execution_mode=%v", payload["execution_mode"])
 	}
 }
+
+func TestResolvePurchaseSpec_请求体上限在进入数据库前拒绝(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	router := gin.New()
+	Register(router, nil, nil, service.AIEndpointPolicy{})
+	body := bytes.Repeat([]byte("x"), service.MaxPurchaseSpecResolutionBodyBytes+1)
+	request := httptest.NewRequest(http.MethodPost,
+		"/api/v1/client/tasks/cg255/spec-resolution", bytes.NewReader(body))
+	request.Header.Set("X-Client-Id", "CLIENT-255")
+	request.Header.Set("Idempotency-Key", "spec-resolution-v1:"+strings.Repeat("0", 64))
+	recorder := httptest.NewRecorder()
+
+	router.ServeHTTP(recorder, request)
+	if recorder.Code != http.StatusBadRequest || !strings.Contains(recorder.Body.String(), `"code":"INVALID_BODY"`) {
+		t.Fatalf("status=%d body=%s", recorder.Code, recorder.Body.String())
+	}
+}
diff --git a/admin/main.go b/admin/main.go
index 04aac4c..81273b1 100644
--- a/admin/main.go
+++ b/admin/main.go
@@ -128,7 +128,7 @@ func newRouter(db *sql.DB) (*gin.Engine, error) {
 	aiSecrets := service.NewFileAISecretStore(aiConfig.SecretsPath)
 	aiPolicy := service.NewAIEndpointPolicy(aiConfig.AllowedHosts)
 	web.Register(r, db, config.OnlineThreshold, aiSecrets, aiPolicy) // 给浏览器的页面
-	api.Register(r, db)                                              // 给 Client 的接口
+	api.Register(r, db, aiSecrets, aiPolicy)                         // 给 Client 的接口
 	catalogConfig, err := config.LoadCatalogIntegration()
 	if err != nil {
 		return nil, fmt.Errorf("读取商品目录接口配置失败: %w", err)
diff --git a/admin/repository/task.go b/admin/repository/task.go
index d3de472..35ca24b 100644
--- a/admin/repository/task.go
+++ b/admin/repository/task.go
@@ -306,20 +306,25 @@ func HasEverClaimed(q Execer, taskID, clientID string) (bool, error) {
 // TaskInfo 是提交结果时需要知道的任务基本信息。
 type TaskInfo struct {
 	TaskType model.TaskType
+	// Version 是 Client 领取任务时拿到的乐观版本号。
+	Version int64
 	// GoodsID 是关联的**蝦皮**商品编号。
 	GoodsID string
 	// PddGoodsID 是要采集/购买的**拼多多**商品编号。
 	// 采集结果落到 pdd_products 时用的是它，不是 GoodsID —— 被采集的是 PDD 商品。
 	PddGoodsID string
+	// PddOptions 是任务创建时固定的目标规格 JSON。
+	// 运行时规格解析必须逐项核对，不能接受 Client 临时改写目标规格。
+	PddOptions string
 }
 
-// GetTaskInfo 查任务的类型和关联商品。任务不存在时返回 (nil, nil)。
+// GetTaskInfo 查任务的类型、版本和关联商品。任务不存在时返回 (nil, nil)。
 func GetTaskInfo(q Execer, taskID string) (*TaskInfo, error) {
 	var info TaskInfo
-	var gid, pddGID sql.NullString
+	var gid, pddGID, pddOptions sql.NullString
 	err := q.QueryRow(
-		`SELECT task_type, goods_id, pdd_goods_id FROM tasks WHERE task_id = ?`,
-		taskID).Scan(&info.TaskType, &gid, &pddGID)
+		`SELECT task_type,version,goods_id,pdd_goods_id,pdd_options FROM tasks WHERE task_id = ?`,
+		taskID).Scan(&info.TaskType, &info.Version, &gid, &pddGID, &pddOptions)
 	if err == sql.ErrNoRows {
 		return nil, nil
 	}
@@ -328,6 +333,7 @@ func GetTaskInfo(q Execer, taskID string) (*TaskInfo, error) {
 	}
 	info.GoodsID = gid.String
 	info.PddGoodsID = pddGID.String
+	info.PddOptions = pddOptions.String
 	return &info, nil
 }
 
diff --git a/admin/service/ai_specmatch.go b/admin/service/ai_specmatch.go
index f9e0d01..d708b50 100644
--- a/admin/service/ai_specmatch.go
+++ b/admin/service/ai_specmatch.go
@@ -153,55 +153,39 @@ func MatchSybSpecWithAI(ctx context.Context, db *sql.DB, actor *model.User, snap
 	}
 	bindings := bindAICandidates(eligible)
 	baseDecision.CandidatesJSON = candidateAuditJSON(bindings)
-	if snapshot.Client == nil || snapshot.Secret == "" || snapshot.Provider.ProviderID == "" {
-		return recordAIMatchWithoutSave(db, baseDecision, "failed", "AI 服务商运行快照不可用")
-	}
 	request := AIModelMatchRequest{ProductTitle: truncateRunes(orderContext.Order.Title, 300), SourceSpec: truncateRunes(orderContext.Order.ProductSpec, 300)}
 	for _, binding := range bindings {
 		request.Candidates = append(request.Candidates, AIModelCandidate{ID: binding.ID,
 			Label: truncateRunes(binding.Choice.Label, 300), Options: boundedAIOptions(binding.Choice.Options)})
 	}
-	response, modelErr := snapshot.Client.Match(ctx, snapshot.Provider, snapshot.Secret, request)
-	if modelErr != nil {
-		result, auditErr := recordAIMatchWithoutSave(db, baseDecision, "failed", safeAIError(modelErr))
-		result.ModelCalled = true
-		return result, auditErr
-	}
-	if err := validateAIModelMatchResponse(response); err != nil {
-		result, auditErr := recordAIMatchWithoutSave(db, baseDecision, "failed", err.Error())
-		result.ModelCalled = true
-		return result, auditErr
-	}
+	selection := selectAIWhitelistedCandidate(ctx, snapshot, request)
+	response := selection.Response
 	baseDecision.ChosenCandidateID = response.CandidateID
 	baseDecision.ConfidenceBPS = response.ConfidenceBPS
-	baseDecision.ConfidenceSet = true
-	baseDecision.Reason = response.Reason
+	baseDecision.ConfidenceSet = selection.ConfidenceSet
+	baseDecision.Reason = selection.Reason
 	baseDecision.ConflictDimensionsJSON = stringArrayJSON(response.ConflictDimensions)
 	baseDecision.MissingDimensionsJSON = stringArrayJSON(response.MissingDimensions)
-	if response.Conclusion != "match" {
-		result, auditErr := recordAIMatchWithoutSave(db, baseDecision, "rejected", response.Reason)
-		result.ModelCalled = true
+	if selection.Status != aiSelectionMatched {
+		outcome := "rejected"
+		if selection.Status == aiSelectionFailed {
+			outcome = "failed"
+		}
+		result, auditErr := recordAIMatchWithoutSave(db, baseDecision, outcome, selection.Reason)
+		result.ModelCalled = selection.ModelCalled
 		return result, auditErr
 	}
 	selected, found := bindingByID(bindings, response.CandidateID)
 	if !found {
-		result, auditErr := recordAIMatchWithoutSave(db, baseDecision, "rejected", "模型返回了不在候选白名单中的编号")
-		result.ModelCalled = true
+		// selectAIWhitelistedCandidate 已核对过同一 request；此分支只防以后
+		// 绑定构造被改坏时把错误候选写进真实映射。
+		result, auditErr := recordAIMatchWithoutSave(db, baseDecision, "rejected", "候选绑定已变化，未保存映射")
+		result.ModelCalled = selection.ModelCalled
 		return result, auditErr
 	}
 	baseDecision.ChosenOptionKey = selected.Choice.Key
-	if len(response.ConflictDimensions) > 0 || len(response.MissingDimensions) > 0 {
-		result, auditErr := recordAIMatchWithoutSave(db, baseDecision, "rejected", "模型报告仍有冲突或缺失维度")
-		result.ModelCalled = true
-		return result, auditErr
-	}
-	if response.ConfidenceBPS < snapshot.Provider.ConfidenceThresholdBPS {
-		result, auditErr := recordAIMatchWithoutSave(db, baseDecision, "rejected", "模型置信度低于管理员设置的自动写入阈值")
-		result.ModelCalled = true
-		return result, auditErr
-	}
 	result, err := saveAutomaticMapping(db, *actor, *orderContext, selected.Choice, "ai", baseDecision)
-	result.ModelCalled = true
+	result.ModelCalled = selection.ModelCalled
 	return result, err
 }
 
diff --git a/admin/service/ai_specmatch_client.go b/admin/service/ai_specmatch_client.go
index 01adf03..9cb46e0 100644
--- a/admin/service/ai_specmatch_client.go
+++ b/admin/service/ai_specmatch_client.go
@@ -39,6 +39,78 @@ type AIModelClient interface {
 	Match(context.Context, model.AIProviderConfig, string, AIModelMatchRequest) (AIModelMatchResponse, error)
 }
 
+type aiWhitelistedSelectionStatus string
+
+const (
+	aiSelectionMatched              aiWhitelistedSelectionStatus = "matched"
+	aiSelectionUncertain            aiWhitelistedSelectionStatus = "uncertain"
+	aiSelectionConflict             aiWhitelistedSelectionStatus = "conflict"
+	aiSelectionFailed               aiWhitelistedSelectionStatus = "failed"
+	aiSelectionCandidateRejected    aiWhitelistedSelectionStatus = "candidate_rejected"
+	aiSelectionDimensionsUnresolved aiWhitelistedSelectionStatus = "dimensions_unresolved"
+	aiSelectionBelowThreshold       aiWhitelistedSelectionStatus = "below_threshold"
+)
+
+// aiWhitelistedSelection 是 SYB 批量匹配和 Client 真机匹配共用的模型安全结论。
+// 业务编排可以把“不确定”显示成不同文案，但不能绕过这里的候选、阈值和维度门禁。
+type aiWhitelistedSelection struct {
+	Status        aiWhitelistedSelectionStatus
+	Response      AIModelMatchResponse
+	Reason        string
+	ConfidenceSet bool
+	ModelCalled   bool
+}
+
+func selectAIWhitelistedCandidate(ctx context.Context, snapshot AIMatchSnapshot,
+	request AIModelMatchRequest) aiWhitelistedSelection {
+	if snapshot.Client == nil || snapshot.Secret == "" || snapshot.Provider.ProviderID == "" {
+		return aiWhitelistedSelection{Status: aiSelectionFailed, Reason: "AI 服务商运行快照不可用"}
+	}
+	response, err := snapshot.Client.Match(ctx, snapshot.Provider, snapshot.Secret, request)
+	if err != nil {
+		reason := safeAIError(err)
+		if snapshot.Secret != "" {
+			reason = strings.ReplaceAll(reason, snapshot.Secret, "[REDACTED]")
+		}
+		return aiWhitelistedSelection{Status: aiSelectionFailed, Reason: reason, ModelCalled: true}
+	}
+	result := aiWhitelistedSelection{Response: response, Reason: response.Reason,
+		ConfidenceSet: true, ModelCalled: true}
+	if err := validateAIModelMatchResponse(response); err != nil {
+		result.Status, result.Reason, result.ConfidenceSet = aiSelectionFailed, err.Error(), false
+		return result
+	}
+	if response.Conclusion == "uncertain" {
+		result.Status = aiSelectionUncertain
+		return result
+	}
+	if response.Conclusion == "conflict" {
+		result.Status = aiSelectionConflict
+		return result
+	}
+	allowed := false
+	for _, candidate := range request.Candidates {
+		if candidate.ID == response.CandidateID {
+			allowed = true
+			break
+		}
+	}
+	if !allowed {
+		result.Status, result.Reason = aiSelectionCandidateRejected, "模型返回了不在候选白名单中的编号"
+		return result
+	}
+	if len(response.ConflictDimensions) > 0 || len(response.MissingDimensions) > 0 {
+		result.Status, result.Reason = aiSelectionDimensionsUnresolved, "模型报告仍有冲突或缺失维度"
+		return result
+	}
+	if response.ConfidenceBPS < snapshot.Provider.ConfidenceThresholdBPS {
+		result.Status, result.Reason = aiSelectionBelowThreshold, "模型置信度低于管理员设置的自动选择阈值"
+		return result
+	}
+	result.Status = aiSelectionMatched
+	return result
+}
+
 type OpenAICompatibleModelClient struct{ doer AIHTTPDoer }
 
 func NewOpenAICompatibleModelClient(doer AIHTTPDoer) *OpenAICompatibleModelClient {
diff --git a/admin/service/purchase_spec_resolution.go b/admin/service/purchase_spec_resolution.go
new file mode 100644
index 0000000..1543046
--- /dev/null
+++ b/admin/service/purchase_spec_resolution.go
@@ -0,0 +1,677 @@
+package service
+
+import (
+	"context"
+	"crypto/sha256"
+	"database/sql"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"reflect"
+	"regexp"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+	"unicode"
+	"unicode/utf8"
+
+	"cmautobuy/admin/model"
+	"cmautobuy/admin/repository"
+)
+
+const (
+	// MaxPurchaseSpecResolutionBodyBytes 是 Client 运行时规格解析请求的硬上限。
+	MaxPurchaseSpecResolutionBodyBytes = 64 << 10
+	PurchaseSpecRulesVersion           = "purchase_rules_v1"
+	purchaseSpecSchemaVersion          = 1
+)
+
+var (
+	ErrInvalidSpecResolutionBody    = errors.New("采购运行时规格解析请求体无效")
+	ErrInvalidSpecResolutionSchema  = errors.New("采购运行时规格解析 schema 不支持")
+	ErrInvalidSpecResolutionRequest = errors.New("采购运行时规格解析字段无效")
+	ErrSpecResolutionHashMismatch   = errors.New("采购运行时规格解析哈希不一致")
+	ErrTaskNotPurchase              = errors.New("任务不是采购任务")
+	ErrTaskVersionConflict          = errors.New("任务版本不一致")
+	ErrPDDGoodsMismatch             = errors.New("PDD 商品不一致")
+	ErrSpecResolutionUnavailable    = errors.New("采购运行时规格解析服务暂不可用")
+)
+
+// PurchaseSpecCandidate 是 Client 当前页面上一个可购买尺码的逐字快照。
+// candidate_id 只在本次请求内有效，AI 只能从这些短编号中选择。
+type PurchaseSpecCandidate struct {
+	CandidateID string            `json:"candidate_id"`
+	RawText     string            `json:"raw_text"`
+	Options     map[string]string `json:"options"`
+}
+
+// PurchaseSpecResolutionRequest 是 docs/client/04-admin-api-contract.md §7.1 的请求体。
+type PurchaseSpecResolutionRequest struct {
+	SchemaVersion         int                     `json:"schema_version"`
+	TaskVersion           int64                   `json:"task_version"`
+	AttemptID             string                  `json:"attempt_id"`
+	PddGoodsID            string                  `json:"pdd_goods_id"`
+	OriginalOptions       map[string]string       `json:"original_options"`
+	SelectedColor         string                  `json:"selected_color"`
+	TargetSize            string                  `json:"target_size"`
+	Candidates            []PurchaseSpecCandidate `json:"candidates"`
+	CandidateSnapshotHash string                  `json:"candidate_snapshot_hash"`
+	ObservedAt            string                  `json:"observed_at"`
+}
+
+type PurchaseSpecResolutionMatch struct {
+	CandidateID string            `json:"candidate_id"`
+	RawText     string            `json:"raw_text"`
+	Options     map[string]string `json:"options"`
+}
+
+// PurchaseSpecResolutionResponse 只返回请求候选的逐字副本，不返回模型生成的新规格。
+type PurchaseSpecResolutionResponse struct {
+	SchemaVersion         int                                 `json:"schema_version"`
+	ResolutionID          string                              `json:"resolution_id"`
+	Outcome               model.PurchaseSpecResolutionOutcome `json:"outcome"`
+	Source                *model.PurchaseSpecResolutionSource `json:"source"`
+	CandidateSnapshotHash string                              `json:"candidate_snapshot_hash"`
+	Match                 *PurchaseSpecResolutionMatch        `json:"match"`
+	ConfidenceBPS         *int                                `json:"confidence_bps"`
+	Reason                string                              `json:"reason"`
+	ResolvedAt            string                              `json:"resolved_at"`
+}
+
+type purchaseSpecDecision struct {
+	Outcome       model.PurchaseSpecResolutionOutcome
+	Source        model.PurchaseSpecResolutionSource
+	Candidate     *PurchaseSpecCandidate
+	ConfidenceBPS int
+	ConfidenceSet bool
+	Reason        string
+	ProviderID    string
+	SourceModel   string
+	Fingerprint   string
+	PromptVersion string
+}
+
+type purchaseSpecGate struct {
+	token chan struct{}
+	refs  int
+}
+
+var purchaseSpecGates = struct {
+	sync.Mutex
+	items map[string]*purchaseSpecGate
+}{items: map[string]*purchaseSpecGate{}}
+
+// ResolvePurchaseSpec 保存一次真机候选观察，先跑确定性规则，确实不能唯一判断时才调用 AI。
+// 它只写解析审计和幂等响应，不修改任务、PDD 主数据或任何下单安全字段。
+func ResolvePurchaseSpec(ctx context.Context, db *sql.DB, secrets AISecretStore, policy AIEndpointPolicy,
+	taskID, clientID, idempotencyKey string, rawBody []byte) (string, error) {
+	return resolvePurchaseSpecWithSnapshotLoader(ctx, db, secrets, policy, taskID, clientID,
+		idempotencyKey, rawBody, LoadActiveAIMatchSnapshot)
+}
+
+type aiSnapshotLoader func(context.Context, *sql.DB, AISecretStore, AIEndpointPolicy) (AIMatchSnapshot, error)
+
+func resolvePurchaseSpecWithSnapshotLoader(ctx context.Context, db *sql.DB, secrets AISecretStore,
+	policy AIEndpointPolicy, taskID, clientID, idempotencyKey string, rawBody []byte,
+	loadSnapshot aiSnapshotLoader) (string, error) {
+	req, err := parsePurchaseSpecResolutionRequest(taskID, idempotencyKey, rawBody)
+	if err != nil {
+		return "", err
+	}
+	requestHash := repository.HashRequest(rawBody)
+
+	// 同一 Admin 进程内，同一个业务身份只允许一个协程进入模型调用。
+	// 锁不包含数据库事务；不同任务仍可以并行解析。
+	release, err := acquirePurchaseSpecGate(ctx, idempotencyKey)
+	if err != nil {
+		return "", fmt.Errorf("%w: %v", ErrSpecResolutionUnavailable, err)
+	}
+	defer release()
+
+	resolution, leader, replay, err := beginPurchaseSpecResolution(
+		db, taskID, clientID, idempotencyKey, requestHash, req)
+	if err != nil || replay != "" {
+		return replay, err
+	}
+	if !leader && resolution.Outcome != model.PurchaseSpecResolutionPending {
+		return saveReconstructedPurchaseSpecResponse(db, idempotencyKey, requestHash, resolution, req.Candidates)
+	}
+
+	// pending 可能来自进程中断后的原请求。因为本进程已取得该业务身份的唯一门禁，
+	// 可以安全接管；最终 UPDATE 仍只允许 pending 完成一次。
+	decision, terminal := matchPurchaseSpecByRule(req.TargetSize, req.Candidates)
+	if !terminal {
+		decision = matchPurchaseSpecWithAI(ctx, db, secrets, policy, req, loadSnapshot)
+	}
+	if purchaseSpecDiagnosticSource(db, req.PddGoodsID) == "shopee_backfill" {
+		decision.Reason = truncateRunes(decision.Reason+"；诊断来源：shopee_backfill", 500)
+	}
+	return completePurchaseSpecResolution(db, idempotencyKey, requestHash, resolution, req.Candidates, decision)
+}
+
+func parsePurchaseSpecResolutionRequest(taskID, idempotencyKey string, rawBody []byte) (PurchaseSpecResolutionRequest, error) {
+	var req PurchaseSpecResolutionRequest
+	if len(rawBody) == 0 || len(rawBody) > MaxPurchaseSpecResolutionBodyBytes || !utf8.Valid(rawBody) {
+		return req, ErrInvalidSpecResolutionBody
+	}
+	if err := json.Unmarshal(rawBody, &req); err != nil {
+		return req, ErrInvalidSpecResolutionBody
+	}
+	if req.SchemaVersion != purchaseSpecSchemaVersion {
+		return req, ErrInvalidSpecResolutionSchema
+	}
+	if req.TaskVersion <= 0 || !validSpecText(req.AttemptID) || !validSpecText(req.PddGoodsID) ||
+		!validSpecText(req.SelectedColor) || !validSpecText(req.TargetSize) ||
+		len(req.OriginalOptions) < 1 || len(req.OriginalOptions) > 16 ||
+		len(req.Candidates) < 1 || len(req.Candidates) > 100 {
+		return req, ErrInvalidSpecResolutionRequest
+	}
+	for key, value := range req.OriginalOptions {
+		if !validSpecText(key) || !validSpecText(value) {
+			return req, ErrInvalidSpecResolutionRequest
+		}
+	}
+	for index, candidate := range req.Candidates {
+		if candidate.CandidateID != "c"+strconv.Itoa(index+1) || !validSpecText(candidate.RawText) ||
+			len(candidate.Options) != 2 || candidate.Options["color"] != req.SelectedColor ||
+			candidate.Options["size"] != candidate.RawText {
+			return req, ErrInvalidSpecResolutionRequest
+		}
+		if _, ok := candidate.Options["color"]; !ok {
+			return req, ErrInvalidSpecResolutionRequest
+		}
+		if _, ok := candidate.Options["size"]; !ok {
+			return req, ErrInvalidSpecResolutionRequest
+		}
+	}
+	if _, err := time.Parse(time.RFC3339Nano, req.ObservedAt); err != nil {
+		return req, ErrInvalidSpecResolutionRequest
+	}
+	expectedSnapshot := purchaseSpecCandidateSnapshotHash(req)
+	if req.CandidateSnapshotHash != expectedSnapshot || idempotencyKey != purchaseSpecIdempotencyKey(taskID, req) {
+		return req, ErrSpecResolutionHashMismatch
+	}
+	return req, nil
+}
+
+func validSpecText(value string) bool {
+	if value == "" || utf8.RuneCountInString(value) > 191 {
+		return false
+	}
+	for _, r := range value {
+		if unicode.IsControl(r) {
+			return false
+		}
+	}
+	return true
+}
+
+func purchaseSpecCandidateSnapshotHash(req PurchaseSpecResolutionRequest) string {
+	var material strings.Builder
+	material.WriteString(specFrame("spec-resolution-v1"))
+	material.WriteString(specFrame(req.PddGoodsID))
+	material.WriteString(specFrame(req.SelectedColor))
+	material.WriteString(specFrame(strconv.Itoa(len(req.Candidates))))
+	for _, candidate := range req.Candidates {
+		material.WriteString(specFrame(candidate.CandidateID))
+		material.WriteString(specFrame(candidate.RawText))
+		material.WriteString(specFrame(candidate.Options["color"]))
+		material.WriteString(specFrame(candidate.Options["size"]))
+	}
+	return sha256Hex(material.String())
+}
+
+func purchaseSpecIdempotencyKey(taskID string, req PurchaseSpecResolutionRequest) string {
+	material := specFrame(taskID) + specFrame(req.AttemptID) +
+		specFrame(req.CandidateSnapshotHash) + specFrame("spec-resolution-v1")
+	return "spec-resolution-v1:" + sha256Hex(material)
+}
+
+func specFrame(value string) string { return strconv.Itoa(len([]byte(value))) + ":" + value }
+
+func sha256Hex(value string) string {
+	sum := sha256.Sum256([]byte(value))
+	return hex.EncodeToString(sum[:])
+}
+
+func acquirePurchaseSpecGate(ctx context.Context, key string) (func(), error) {
+	purchaseSpecGates.Lock()
+	gate := purchaseSpecGates.items[key]
+	if gate == nil {
+		gate = &purchaseSpecGate{token: make(chan struct{}, 1)}
+		purchaseSpecGates.items[key] = gate
+	}
+	gate.refs++
+	purchaseSpecGates.Unlock()
+
+	select {
+	case gate.token <- struct{}{}:
+		return func() {
+			<-gate.token
+			purchaseSpecGates.Lock()
+			gate.refs--
+			if gate.refs == 0 {
+				delete(purchaseSpecGates.items, key)
+			}
+			purchaseSpecGates.Unlock()
+		}, nil
+	case <-ctx.Done():
+		purchaseSpecGates.Lock()
+		gate.refs--
+		if gate.refs == 0 {
+			delete(purchaseSpecGates.items, key)
+		}
+		purchaseSpecGates.Unlock()
+		return nil, ctx.Err()
+	}
+}
+
+func beginPurchaseSpecResolution(db *sql.DB, taskID, clientID, idempotencyKey, requestHash string,
+	req PurchaseSpecResolutionRequest) (*model.PurchaseSpecResolution, bool, string, error) {
+	tx, err := db.Begin()
+	if err != nil {
+		return nil, false, "", fmt.Errorf("%w: 开始候选观察事务失败", ErrSpecResolutionUnavailable)
+	}
+	defer tx.Rollback()
+	if body, done, lookupErr := repository.LookupIdempotent(tx, idempotencyKey, requestHash); lookupErr != nil {
+		if errors.Is(lookupErr, repository.ErrIdempotencyConflict) {
+			return nil, false, "", ErrIdempotencyConflict
+		}
+		return nil, false, "", fmt.Errorf("%w: 查询幂等结果失败", ErrSpecResolutionUnavailable)
+	} else if done {
+		return nil, false, body, nil
+	}
+	info, err := repository.GetTaskInfo(tx, taskID)
+	if err != nil {
+		return nil, false, "", fmt.Errorf("%w: 查询任务失败", ErrSpecResolutionUnavailable)
+	}
+	if info == nil {
+		return nil, false, "", ErrTaskNotFound
+	}
+	if info.TaskType != model.TaskPurchase {
+		return nil, false, "", ErrTaskNotPurchase
+	}
+	if info.Version != req.TaskVersion {
+		return nil, false, "", ErrTaskVersionConflict
+	}
+	if info.PddGoodsID != req.PddGoodsID {
+		return nil, false, "", ErrPDDGoodsMismatch
+	}
+	if !taskOptionsEqual(info.PddOptions, req.OriginalOptions) ||
+		!targetOptionWasClaimed(req.OriginalOptions, "color", req.SelectedColor) ||
+		!targetOptionWasClaimed(req.OriginalOptions, "size", req.TargetSize) {
+		return nil, false, "", ErrInvalidSpecResolutionRequest
+	}
+	claimed, err := repository.HasEverClaimed(tx, taskID, clientID)
+	if err != nil {
+		return nil, false, "", fmt.Errorf("%w: 查询任务领取历史失败", ErrSpecResolutionUnavailable)
+	}
+	if !claimed {
+		return nil, false, "", ErrNeverClaimed
+	}
+
+	originalJSON, _ := json.Marshal(req.OriginalOptions)
+	candidatesJSON, _ := json.Marshal(req.Candidates)
+	resolution := &model.PurchaseSpecResolution{
+		ResolutionID: "psr-" + newID(), TaskID: taskID, AttemptID: req.AttemptID, ClientID: clientID,
+		TaskVersion: req.TaskVersion, PddGoodsID: req.PddGoodsID,
+		OriginalOptionsJSON: string(originalJSON), SelectedColor: req.SelectedColor, TargetSize: req.TargetSize,
+		CandidatesJSON: string(candidatesJSON), CandidateSnapshotHash: req.CandidateSnapshotHash,
+		RequestHash: requestHash, ObservedAt: req.ObservedAt, Outcome: model.PurchaseSpecResolutionPending,
+		CreatedAt: model.NowISO(),
+	}
+	if err := repository.InsertPurchaseSpecResolution(tx, *resolution); err != nil {
+		if !errors.Is(err, repository.ErrPurchaseSpecResolutionExists) {
+			return nil, false, "", fmt.Errorf("%w: 保存候选观察失败", ErrSpecResolutionUnavailable)
+		}
+		// MySQL 默认 REPEATABLE READ：本事务前面已经做过一致性读，唯一键等待
+		// 另一事务提交后，继续在原事务查询仍可能看不到赢家。先回滚再用新快照复查。
+		if rollbackErr := tx.Rollback(); rollbackErr != nil && !errors.Is(rollbackErr, sql.ErrTxDone) {
+			return nil, false, "", fmt.Errorf("%w: 回滚重复候选观察失败", ErrSpecResolutionUnavailable)
+		}
+		existing, replayErr := repository.GetPurchaseSpecResolutionForReplay(
+			db, taskID, req.AttemptID, req.CandidateSnapshotHash, requestHash)
+		if errors.Is(replayErr, repository.ErrPurchaseSpecResolutionConflict) {
+			return nil, false, "", ErrIdempotencyConflict
+		}
+		if replayErr != nil || existing == nil {
+			return nil, false, "", fmt.Errorf("%w: 读取已有候选观察失败", ErrSpecResolutionUnavailable)
+		}
+		return existing, false, "", nil
+	}
+	if err := tx.Commit(); err != nil {
+		return nil, false, "", fmt.Errorf("%w: 提交候选观察失败", ErrSpecResolutionUnavailable)
+	}
+	return resolution, true, "", nil
+}
+
+func taskOptionsEqual(raw string, submitted map[string]string) bool {
+	var expected map[string]string
+	return json.Unmarshal([]byte(raw), &expected) == nil && reflect.DeepEqual(expected, submitted)
+}
+
+func targetOptionWasClaimed(options map[string]string, preferredKey, target string) bool {
+	if value, ok := options[preferredKey]; ok {
+		return value == target
+	}
+	for _, value := range options {
+		if value == target {
+			return true
+		}
+	}
+	return false
+}
+
+func purchaseSpecDiagnosticSource(db *sql.DB, goodsID string) string {
+	product, err := repository.GetPddProductByGoodsID(db, goodsID)
+	if err != nil || product == nil || strings.TrimSpace(product.SkusJSON) == "" {
+		return ""
+	}
+	var metadata struct {
+		SpecSource string `json:"spec_source"`
+	}
+	if json.Unmarshal([]byte(product.SkusJSON), &metadata) != nil {
+		return ""
+	}
+	return strings.TrimSpace(metadata.SpecSource)
+}
+
+var runtimeWeightPattern = regexp.MustCompile(`(?i)^\s*(\d+(?:\.\d+)?)\s*(?:[-~～—–至到]\s*(\d+(?:\.\d+)?))?\s*(公斤|kg|kgs|千克|斤)\s*$`)
+
+type runtimeWeightRange struct{ fromJin, toJin float64 }
+
+func matchPurchaseSpecByRule(target string, candidates []PurchaseSpecCandidate) (purchaseSpecDecision, bool) {
+	matches := make([]PurchaseSpecCandidate, 0, 1)
+	for _, candidate := range candidates {
+		if runtimeSpecsEquivalent(target, candidate.RawText) {
+			matches = append(matches, candidate)
+		}
+	}
+	if len(matches) == 1 {
+		return purchaseSpecDecision{Outcome: model.PurchaseSpecResolutionMatched,
+			Source: model.PurchaseSpecResolutionRule, Candidate: &matches[0],
+			ConfidenceBPS: 10000, ConfidenceSet: true,
+			Reason: "目标尺码与唯一真机候选按确定性规则等价"}, true
+	}
+	if len(matches) > 1 {
+		return purchaseSpecDecision{Outcome: model.PurchaseSpecResolutionUncertain,
+			Source: model.PurchaseSpecResolutionRule,
+			Reason: "存在多个与目标尺码等价的真机候选，不能安全自动选择"}, true
+	}
+	// 两个重量区间同时覆盖目标时，模型也没有可靠信号判断页面上的业务边界，
+	// 直接返回不确定，避免让语言模型替代真实尺码规则猜一个。
+	if targetWeight, ok := parseRuntimeWeightRange(target); ok {
+		overlaps := 0
+		for _, candidate := range candidates {
+			if candidateWeight, candidateOK := parseRuntimeWeightRange(candidate.RawText); candidateOK &&
+				weightRangesOverlap(targetWeight, candidateWeight) {
+				overlaps++
+			}
+		}
+		if overlaps > 1 {
+			return purchaseSpecDecision{Outcome: model.PurchaseSpecResolutionUncertain,
+				Source: model.PurchaseSpecResolutionRule,
+				Reason: "目标重量区间同时落入多个真机候选，不能安全自动选择"}, true
+		}
+	}
+	return purchaseSpecDecision{}, false
+}
+
+func runtimeSpecsEquivalent(left, right string) bool {
+	a, okA := parseRuntimeWeightRange(left)
+	b, okB := parseRuntimeWeightRange(right)
+	if okA || okB {
+		return okA && okB && almostEqual(a.fromJin, b.fromJin) && almostEqual(a.toJin, b.toJin)
+	}
+	return normalizeRuntimeSpec(left) == normalizeRuntimeSpec(right)
+}
+
+func normalizeRuntimeSpec(raw string) string {
+	raw = simplifyExplicit(raw)
+	for _, pair := range []struct{ from, to string }{
+		{"體", "体"}, {"號", "号"}, {"圍", "围"}, {"寬", "宽"}, {"適", "适"},
+		{"齡", "龄"}, {"歲", "岁"}, {"單", "单"}, {"雙", "双"}, {"釐", "厘"},
+		{"臺", "台"}, {"兒", "儿"}, {"婦", "妇"}, {"標", "标"}, {"準", "准"},
+		{"顏", "颜"}, {"議", "议"}, {"鬆", "松"}, {"褲", "裤"}, {"絨", "绒"},
+		{"寶", "宝"}, {"嬰", "婴"},
+	} {
+		raw = strings.ReplaceAll(raw, pair.from, pair.to)
+	}
+	var result strings.Builder
+	for _, r := range strings.ToLower(raw) {
+		// 加减号和范围符号可能是尺码语义（例如 M+、50-60kg），不能为了
+		// “忽略符号”把两个不同规格折叠成同一个。斜杠、括号、冒号等展示
+		// 分隔符才可以安全忽略。
+		if strings.ContainsRune("+-~～—–至到", r) {
+			result.WriteRune(r)
+			continue
+		}
+		if unicode.IsSpace(r) || unicode.IsPunct(r) || unicode.IsSymbol(r) {
+			continue
+		}
+		result.WriteRune(r)
+	}
+	return result.String()
+}
+
+func parseRuntimeWeightRange(raw string) (runtimeWeightRange, bool) {
+	raw = strings.TrimFunc(raw, func(r rune) bool {
+		return (unicode.IsPunct(r) || unicode.IsSymbol(r)) && !strings.ContainsRune("+-~～—–", r)
+	})
+	match := runtimeWeightPattern.FindStringSubmatch(simplifyExplicit(raw))
+	if len(match) == 0 {
+		return runtimeWeightRange{}, false
+	}
+	from, err := strconv.ParseFloat(match[1], 64)
+	if err != nil || from <= 0 {
+		return runtimeWeightRange{}, false
+	}
+	to := from
+	if match[2] != "" {
+		to, err = strconv.ParseFloat(match[2], 64)
+		if err != nil || to <= 0 || from > to {
+			return runtimeWeightRange{}, false
+		}
+	}
+	if unit := strings.ToLower(match[3]); unit == "公斤" || unit == "kg" || unit == "kgs" || unit == "千克" {
+		from *= 2
+		to *= 2
+	}
+	return runtimeWeightRange{fromJin: from, toJin: to}, true
+}
+
+func weightRangesOverlap(left, right runtimeWeightRange) bool {
+	return left.fromJin <= right.toJin && right.fromJin <= left.toJin
+}
+
+func almostEqual(left, right float64) bool {
+	delta := left - right
+	if delta < 0 {
+		delta = -delta
+	}
+	return delta < 0.000001
+}
+
+func matchPurchaseSpecWithAI(ctx context.Context, db *sql.DB, secrets AISecretStore,
+	policy AIEndpointPolicy, req PurchaseSpecResolutionRequest, loadSnapshot aiSnapshotLoader) purchaseSpecDecision {
+	snapshot, err := loadSnapshot(ctx, db, secrets, policy)
+	if err != nil {
+		return purchaseSpecDecision{Outcome: model.PurchaseSpecResolutionFailed,
+			Reason: truncateRunes("AI 运行配置不可用："+safeAIError(err), 500)}
+	}
+	base := purchaseSpecDecision{Source: model.PurchaseSpecResolutionAI,
+		ProviderID: snapshot.Provider.ProviderID, SourceModel: snapshot.Provider.Model,
+		Fingerprint: snapshot.ConfigFingerprint, PromptVersion: AISpecMatchPromptVersion}
+	request := AIModelMatchRequest{
+		SourceSpec: "已选择颜色：" + truncateRunes(req.SelectedColor, 191) + "；任务目标尺码：" + truncateRunes(req.TargetSize, 191),
+	}
+	for _, candidate := range req.Candidates {
+		request.Candidates = append(request.Candidates, AIModelCandidate{
+			ID: candidate.CandidateID, Label: candidate.RawText, Options: boundedAIOptions(candidate.Options),
+		})
+	}
+	selection := selectAIWhitelistedCandidate(ctx, snapshot, request)
+	response := selection.Response
+	base.ConfidenceBPS, base.ConfidenceSet, base.Reason = response.ConfidenceBPS, selection.ConfidenceSet, selection.Reason
+	switch selection.Status {
+	case aiSelectionFailed:
+		base.Outcome = model.PurchaseSpecResolutionFailed
+		return base
+	case aiSelectionUncertain, aiSelectionDimensionsUnresolved, aiSelectionBelowThreshold:
+		base.Outcome = model.PurchaseSpecResolutionUncertain
+		return base
+	case aiSelectionConflict, aiSelectionCandidateRejected:
+		base.Outcome = model.PurchaseSpecResolutionRejected
+		return base
+	}
+	var selected *PurchaseSpecCandidate
+	for index := range req.Candidates {
+		if req.Candidates[index].CandidateID == response.CandidateID {
+			selected = &req.Candidates[index]
+			break
+		}
+	}
+	if selected == nil {
+		base.Outcome, base.Reason = model.PurchaseSpecResolutionRejected, "候选绑定已变化，未返回匹配"
+		return base
+	}
+	base.Outcome, base.Candidate = model.PurchaseSpecResolutionMatched, selected
+	return base
+}
+
+func completePurchaseSpecResolution(db *sql.DB, idempotencyKey, requestHash string,
+	resolution *model.PurchaseSpecResolution, candidates []PurchaseSpecCandidate,
+	result purchaseSpecDecision) (string, error) {
+	tx, err := db.Begin()
+	if err != nil {
+		return "", fmt.Errorf("%w: 开始保存解析结论事务失败", ErrSpecResolutionUnavailable)
+	}
+	defer tx.Rollback()
+	if body, done, lookupErr := repository.LookupIdempotent(tx, idempotencyKey, requestHash); lookupErr != nil {
+		if errors.Is(lookupErr, repository.ErrIdempotencyConflict) {
+			return "", ErrIdempotencyConflict
+		}
+		return "", fmt.Errorf("%w: 查询幂等结果失败", ErrSpecResolutionUnavailable)
+	} else if done {
+		return body, nil
+	}
+
+	decidedAt := model.NowISO()
+	decision := model.PurchaseSpecResolutionDecision{
+		ResolutionID: resolution.ResolutionID, Outcome: result.Outcome, DecisionSource: result.Source,
+		ConfidenceBPS: result.ConfidenceBPS, ConfidenceSet: result.ConfidenceSet,
+		Reason: truncateRunes(result.Reason, 500), ProviderID: result.ProviderID,
+		SourceModel: result.SourceModel, ConfigFingerprint: result.Fingerprint,
+		RulesVersion: PurchaseSpecRulesVersion, PromptVersion: result.PromptVersion, DecidedAt: decidedAt,
+	}
+	if result.Candidate != nil {
+		decision.ChosenCandidateID = result.Candidate.CandidateID
+		resolvedJSON, _ := json.Marshal(result.Candidate.Options)
+		decision.ResolvedOptionsJSON = string(resolvedJSON)
+	}
+	if err := repository.CompletePurchaseSpecResolution(tx, decision); err != nil {
+		if errors.Is(err, repository.ErrPurchaseSpecResolutionCompleted) {
+			if rollbackErr := tx.Rollback(); rollbackErr != nil && !errors.Is(rollbackErr, sql.ErrTxDone) {
+				return "", fmt.Errorf("回滚并发规格解析失败: %w", rollbackErr)
+			}
+			existing, readErr := repository.GetPurchaseSpecResolutionForReplay(
+				db, resolution.TaskID, resolution.AttemptID, resolution.CandidateSnapshotHash, requestHash)
+			if readErr != nil || existing == nil || existing.Outcome == model.PurchaseSpecResolutionPending {
+				return "", fmt.Errorf("%w: 读取并发解析结论失败", ErrSpecResolutionUnavailable)
+			}
+			return saveReconstructedPurchaseSpecResponse(db, idempotencyKey, requestHash, existing, candidates)
+		}
+		return "", fmt.Errorf("%w: 保存解析结论失败", ErrSpecResolutionUnavailable)
+	}
+	response := purchaseSpecResponse(resolution.ResolutionID, resolution.CandidateSnapshotHash,
+		decidedAt, result.Outcome, result.Source, result.Candidate, result.ConfidenceBPS,
+		result.ConfidenceSet, decision.Reason)
+	body, err := json.Marshal(response)
+	if err != nil {
+		return "", fmt.Errorf("序列化规格解析响应失败: %w", err)
+	}
+	if err := repository.SaveIdempotent(tx, idempotencyKey, requestHash, string(body)); err != nil {
+		if errors.Is(err, repository.ErrIdempotencyAlreadySaved) {
+			if rollbackErr := tx.Rollback(); rollbackErr != nil && !errors.Is(rollbackErr, sql.ErrTxDone) {
+				return "", fmt.Errorf("回滚重复规格解析失败: %w", rollbackErr)
+			}
+			replayed, done, lookupErr := repository.LookupIdempotent(db, idempotencyKey, requestHash)
+			if lookupErr != nil || !done {
+				return "", fmt.Errorf("%w: 读取并发幂等响应失败", ErrSpecResolutionUnavailable)
+			}
+			return replayed, nil
+		}
+		return "", fmt.Errorf("%w: 保存规格解析幂等响应失败", ErrSpecResolutionUnavailable)
+	}
+	if err := repository.TouchClient(tx, resolution.ClientID); err != nil {
+		return "", fmt.Errorf("%w: 刷新客户端活动时间失败", ErrSpecResolutionUnavailable)
+	}
+	if err := tx.Commit(); err != nil {
+		return "", fmt.Errorf("%w: 提交规格解析结论失败", ErrSpecResolutionUnavailable)
+	}
+	return string(body), nil
+}
+
+func saveReconstructedPurchaseSpecResponse(db *sql.DB, idempotencyKey, requestHash string,
+	resolution *model.PurchaseSpecResolution, candidates []PurchaseSpecCandidate) (string, error) {
+	var candidate *PurchaseSpecCandidate
+	for index := range candidates {
+		if candidates[index].CandidateID == resolution.ChosenCandidateID {
+			candidate = &candidates[index]
+			break
+		}
+	}
+	if resolution.Outcome == model.PurchaseSpecResolutionMatched && candidate == nil {
+		return "", fmt.Errorf("%w: 已保存结论的候选编号不在请求快照中", ErrSpecResolutionUnavailable)
+	}
+	response := purchaseSpecResponse(resolution.ResolutionID, resolution.CandidateSnapshotHash,
+		resolution.DecidedAt, resolution.Outcome, resolution.DecisionSource, candidate,
+		resolution.ConfidenceBPS, resolution.ConfidenceSet, resolution.Reason)
+	body, err := json.Marshal(response)
+	if err != nil {
+		return "", err
+	}
+	tx, err := db.Begin()
+	if err != nil {
+		return "", fmt.Errorf("%w: 开始恢复幂等响应事务失败", ErrSpecResolutionUnavailable)
+	}
+	defer tx.Rollback()
+	if replayed, done, lookupErr := repository.LookupIdempotent(tx, idempotencyKey, requestHash); lookupErr != nil {
+		if errors.Is(lookupErr, repository.ErrIdempotencyConflict) {
+			return "", ErrIdempotencyConflict
+		}
+		return "", lookupErr
+	} else if done {
+		return replayed, nil
+	}
+	if err := repository.SaveIdempotent(tx, idempotencyKey, requestHash, string(body)); err != nil {
+		return "", err
+	}
+	if err := tx.Commit(); err != nil {
+		return "", err
+	}
+	return string(body), nil
+}
+
+func purchaseSpecResponse(resolutionID, snapshotHash, resolvedAt string,
+	outcome model.PurchaseSpecResolutionOutcome, source model.PurchaseSpecResolutionSource,
+	candidate *PurchaseSpecCandidate, confidence int, confidenceSet bool, reason string) PurchaseSpecResolutionResponse {
+	response := PurchaseSpecResolutionResponse{SchemaVersion: purchaseSpecSchemaVersion,
+		ResolutionID: resolutionID, Outcome: outcome, CandidateSnapshotHash: snapshotHash,
+		Reason: reason, ResolvedAt: resolvedAt}
+	if source != "" {
+		value := source
+		response.Source = &value
+	}
+	if confidenceSet {
+		value := confidence
+		response.ConfidenceBPS = &value
+	}
+	if candidate != nil {
+		response.Match = &PurchaseSpecResolutionMatch{CandidateID: candidate.CandidateID,
+			RawText: candidate.RawText, Options: candidate.Options}
+	}
+	return response
+}
diff --git a/admin/service/purchase_spec_resolution_test.go b/admin/service/purchase_spec_resolution_test.go
new file mode 100644
index 0000000..6399bba
--- /dev/null
+++ b/admin/service/purchase_spec_resolution_test.go
@@ -0,0 +1,440 @@
+package service
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"cmautobuy/admin/model"
+	"cmautobuy/admin/repository"
+)
+
+func TestMatchPurchaseSpecByRule_只接受唯一等价候选(t *testing.T) {
+	tests := []struct {
+		name      string
+		target    string
+		values    []string
+		terminal  bool
+		outcome   model.PurchaseSpecResolutionOutcome
+		candidate string
+	}{
+		{name: "逐字相同", target: "M码", values: []string{"S码", "M码"}, terminal: true,
+			outcome: model.PurchaseSpecResolutionMatched, candidate: "c2"},
+		{name: "繁简大小写和展示符号", target: "藍 色 / XL 碼", values: []string{"蓝色／xl码"}, terminal: true,
+			outcome: model.PurchaseSpecResolutionMatched, candidate: "c1"},
+		{name: "公斤和斤单值", target: "60公斤", values: []string{"100斤", "120斤"}, terminal: true,
+			outcome: model.PurchaseSpecResolutionMatched, candidate: "c2"},
+		{name: "公斤和斤正区间", target: "50-60 kg", values: []string{"80~100斤", "100至120斤"}, terminal: true,
+			outcome: model.PurchaseSpecResolutionMatched, candidate: "c2"},
+		{name: "多个重叠区间直接不确定", target: "50-60公斤", values: []string{"90-110斤", "110-130斤"}, terminal: true,
+			outcome: model.PurchaseSpecResolutionUncertain},
+		{name: "倒序区间不自动修正", target: "60-50公斤", values: []string{"100-120斤"}, terminal: false},
+		{name: "加减尺码不能被符号归一化合并", target: "M+", values: []string{"M-"}, terminal: false},
+		{name: "多个等价候选不选一个", target: "60公斤", values: []string{"120斤", "60kg"}, terminal: true,
+			outcome: model.PurchaseSpecResolutionUncertain},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			candidates := runtimeCandidates("黑色", test.values...)
+			decision, terminal := matchPurchaseSpecByRule(test.target, candidates)
+			if terminal != test.terminal || decision.Outcome != test.outcome {
+				t.Fatalf("terminal=%v outcome=%s", terminal, decision.Outcome)
+			}
+			if test.candidate != "" && (decision.Candidate == nil || decision.Candidate.CandidateID != test.candidate) {
+				t.Fatalf("candidate=%+v", decision.Candidate)
+			}
+			if test.outcome != model.PurchaseSpecResolutionMatched && decision.Candidate != nil {
+				t.Fatalf("非 matched 不应返回候选: %+v", decision.Candidate)
+			}
+		})
+	}
+}
+
+func TestParsePurchaseSpecResolutionRequest_校验候选快照和确定性幂等键(t *testing.T) {
+	req, body, key := validRuntimeSpecRequest(t, "cg255", "M码", "S码", "M码")
+	parsed, err := parsePurchaseSpecResolutionRequest("cg255", key, body)
+	if err != nil || parsed.CandidateSnapshotHash != req.CandidateSnapshotHash {
+		t.Fatalf("合法请求解析失败: parsed=%+v err=%v", parsed, err)
+	}
+
+	badHash := append([]byte(nil), body...)
+	var changed map[string]any
+	if err := json.Unmarshal(badHash, &changed); err != nil {
+		t.Fatal(err)
+	}
+	changed["candidate_snapshot_hash"] = "0000000000000000000000000000000000000000000000000000000000000000"
+	badHash, _ = json.Marshal(changed)
+	if _, err := parsePurchaseSpecResolutionRequest("cg255", key, badHash); !errors.Is(err, ErrSpecResolutionHashMismatch) {
+		t.Fatalf("错误快照哈希 err=%v", err)
+	}
+
+	req.Candidates[0].CandidateID = "c2"
+	req.CandidateSnapshotHash = purchaseSpecCandidateSnapshotHash(req)
+	invalidBody, _ := json.Marshal(req)
+	invalidKey := purchaseSpecIdempotencyKey("cg255", req)
+	if _, err := parsePurchaseSpecResolutionRequest("cg255", invalidKey, invalidBody); !errors.Is(err, ErrInvalidSpecResolutionRequest) {
+		t.Fatalf("跳号候选 err=%v", err)
+	}
+
+	tooLarge := make([]byte, MaxPurchaseSpecResolutionBodyBytes+1)
+	if _, err := parsePurchaseSpecResolutionRequest("cg255", key, tooLarge); !errors.Is(err, ErrInvalidSpecResolutionBody) {
+		t.Fatalf("超大请求 err=%v", err)
+	}
+}
+
+type stubAIModelClient struct {
+	response AIModelMatchResponse
+	err      error
+	delay    time.Duration
+	calls    atomic.Int32
+	last     AIModelMatchRequest
+	mu       sync.Mutex
+}
+
+func (client *stubAIModelClient) Match(ctx context.Context, _ model.AIProviderConfig, _ string,
+	request AIModelMatchRequest) (AIModelMatchResponse, error) {
+	client.calls.Add(1)
+	client.mu.Lock()
+	client.last = request
+	client.mu.Unlock()
+	if client.delay > 0 {
+		select {
+		case <-time.After(client.delay):
+		case <-ctx.Done():
+			return AIModelMatchResponse{}, ctx.Err()
+		}
+	}
+	return client.response, client.err
+}
+
+func TestMatchPurchaseSpecWithAI_只接受请求候选并执行安全门禁(t *testing.T) {
+	tests := []struct {
+		name      string
+		response  AIModelMatchResponse
+		modelErr  error
+		threshold int
+		outcome   model.PurchaseSpecResolutionOutcome
+		candidate string
+	}{
+		{name: "白名单内高置信命中", threshold: 8000, outcome: model.PurchaseSpecResolutionMatched, candidate: "c2",
+			response: AIModelMatchResponse{Conclusion: "match", CandidateID: "c2", ConfidenceBPS: 9200, Reason: "唯一对应"}},
+		{name: "越权候选拒绝", threshold: 8000, outcome: model.PurchaseSpecResolutionRejected,
+			response: AIModelMatchResponse{Conclusion: "match", CandidateID: "invented", ConfidenceBPS: 9200, Reason: "错误编号"}},
+		{name: "低于阈值不自动选择", threshold: 9500, outcome: model.PurchaseSpecResolutionUncertain,
+			response: AIModelMatchResponse{Conclusion: "match", CandidateID: "c2", ConfidenceBPS: 9200, Reason: "置信不足"}},
+		{name: "冲突维度不自动选择", threshold: 8000, outcome: model.PurchaseSpecResolutionUncertain,
+			response: AIModelMatchResponse{Conclusion: "match", CandidateID: "c2", ConfidenceBPS: 9200, Reason: "仍缺信息", MissingDimensions: []string{"尺码"}}},
+		{name: "模型格式错误记失败", threshold: 8000, outcome: model.PurchaseSpecResolutionFailed,
+			response: AIModelMatchResponse{Conclusion: "other", ConfidenceBPS: 9200, Reason: "非法"}},
+		{name: "模型超时和密钥不进入原因", threshold: 8000, outcome: model.PurchaseSpecResolutionFailed,
+			modelErr: errors.New("upstream timeout for secret")},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			client := &stubAIModelClient{response: test.response, err: test.modelErr}
+			loader := func(context.Context, *sql.DB, AISecretStore, AIEndpointPolicy) (AIMatchSnapshot, error) {
+				return AIMatchSnapshot{Provider: model.AIProviderConfig{ProviderID: "provider-1", Model: "model-1",
+					ConfidenceThresholdBPS: test.threshold}, ConfigFingerprint: "fingerprint", Secret: "secret", Client: client}, nil
+			}
+			req, _, _ := validRuntimeSpecRequest(t, "cg255", "L码", "M码", "XL码")
+			decision := matchPurchaseSpecWithAI(context.Background(), nil, nil, AIEndpointPolicy{}, req, loader)
+			if decision.Outcome != test.outcome {
+				t.Fatalf("outcome=%s reason=%s", decision.Outcome, decision.Reason)
+			}
+			if test.modelErr != nil && strings.Contains(decision.Reason, "secret") {
+				t.Fatalf("模型错误泄露密钥: %s", decision.Reason)
+			}
+			if test.candidate != "" && (decision.Candidate == nil || decision.Candidate.CandidateID != test.candidate) {
+				t.Fatalf("candidate=%+v", decision.Candidate)
+			}
+			if test.outcome != model.PurchaseSpecResolutionMatched && decision.Candidate != nil {
+				t.Fatalf("非 matched 不得带候选: %+v", decision.Candidate)
+			}
+			if client.calls.Load() != 1 {
+				t.Fatalf("model calls=%d", client.calls.Load())
+			}
+			for index, candidate := range client.last.Candidates {
+				if candidate.ID != fmt.Sprintf("c%d", index+1) {
+					t.Fatalf("AI 候选编号被改写: %+v", client.last.Candidates)
+				}
+			}
+		})
+	}
+}
+
+func TestResolvePurchaseSpec_规则命中幂等且不改任务主数据(t *testing.T) {
+	db := newRuntimeSpecTestDB(t)
+	prepareRuntimeSpecTask(t, db, "cg255-rule", model.TaskPurchase, true, `{"color":"黑色","size":"60公斤"}`)
+	now := model.NowISO()
+	originalSKUs := `{"spec_source":"client","skus":[{"options":{"color":"黑色","size":"60公斤"},"available":true}]}`
+	if _, err := db.Exec(`INSERT INTO pdd_products
+		(goods_id,url,title,skus_json,collect_status,created_at,updated_at)
+		VALUES(?,?,?,?,'collected',?,?)`, "PDD-255", "https://mobile.yangkeduo.com/goods.html?goods_id=PDD-255",
+		"测试商品", originalSKUs, now, now); err != nil {
+		t.Fatal(err)
+	}
+	_, body, key := validRuntimeSpecRequest(t, "cg255-rule", "60公斤", "100斤", "120斤")
+	var loaderCalls atomic.Int32
+	loader := func(context.Context, *sql.DB, AISecretStore, AIEndpointPolicy) (AIMatchSnapshot, error) {
+		loaderCalls.Add(1)
+		return AIMatchSnapshot{}, errors.New("规则命中不应加载 AI")
+	}
+	first, err := resolvePurchaseSpecWithSnapshotLoader(context.Background(), db, nil, AIEndpointPolicy{},
+		"cg255-rule", "CLIENT-255", key, body, loader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	second, err := resolvePurchaseSpecWithSnapshotLoader(context.Background(), db, nil, AIEndpointPolicy{},
+		"cg255-rule", "CLIENT-255", key, body, loader)
+	if err != nil || second != first {
+		t.Fatalf("幂等重放不同: first=%s second=%s err=%v", first, second, err)
+	}
+	if loaderCalls.Load() != 0 {
+		t.Fatalf("规则命中却调用 AI %d 次", loaderCalls.Load())
+	}
+	var response PurchaseSpecResolutionResponse
+	if err := json.Unmarshal([]byte(first), &response); err != nil {
+		t.Fatal(err)
+	}
+	if response.Outcome != model.PurchaseSpecResolutionMatched || response.Source == nil ||
+		*response.Source != model.PurchaseSpecResolutionRule || response.Match == nil || response.Match.CandidateID != "c2" {
+		t.Fatalf("响应错误: %+v", response)
+	}
+	var status, options string
+	var version, maxPrice int64
+	var resultData sql.NullString
+	if err := db.QueryRow(`SELECT status,version,pdd_options,max_price_cent,result_data FROM tasks WHERE task_id=?`, "cg255-rule").
+		Scan(&status, &version, &options, &maxPrice, &resultData); err != nil {
+		t.Fatal(err)
+	}
+	if status != string(model.TaskClaimed) || version != 1 || options != `{"color":"黑色","size":"60公斤"}` ||
+		maxPrice != 2000 || resultData.Valid {
+		t.Fatalf("任务被规格解析改写: status=%s version=%d options=%s max=%d result=%q",
+			status, version, options, maxPrice, resultData.String)
+	}
+	var actualSKUs string
+	if err := db.QueryRow(`SELECT skus_json FROM pdd_products WHERE goods_id='PDD-255'`).Scan(&actualSKUs); err != nil || actualSKUs != originalSKUs {
+		t.Fatalf("PDD 主规格被改写: skus=%s err=%v", actualSKUs, err)
+	}
+	var count int
+	if err := db.QueryRow(`SELECT COUNT(*) FROM purchase_spec_resolutions WHERE task_id=?`, "cg255-rule").Scan(&count); err != nil || count != 1 {
+		t.Fatalf("审计记录 count=%d err=%v", count, err)
+	}
+}
+
+func TestResolvePurchaseSpec_业务权限错误不写解析记录(t *testing.T) {
+	tests := []struct {
+		name     string
+		taskType model.TaskType
+		claimed  bool
+		mutate   func(*PurchaseSpecResolutionRequest)
+		expected error
+	}{
+		{name: "非采购任务", taskType: model.TaskCollect, claimed: true, expected: ErrTaskNotPurchase},
+		{name: "从未领取", taskType: model.TaskPurchase, claimed: false, expected: ErrNeverClaimed},
+		{name: "任务版本冲突", taskType: model.TaskPurchase, claimed: true,
+			mutate: func(req *PurchaseSpecResolutionRequest) { req.TaskVersion = 2 }, expected: ErrTaskVersionConflict},
+		{name: "PDD 商品不一致", taskType: model.TaskPurchase, claimed: true,
+			mutate: func(req *PurchaseSpecResolutionRequest) { req.PddGoodsID = "OTHER" }, expected: ErrPDDGoodsMismatch},
+		{name: "任务原始规格被改写", taskType: model.TaskPurchase, claimed: true,
+			mutate: func(req *PurchaseSpecResolutionRequest) { req.OriginalOptions["size"] = "XL码" }, expected: ErrInvalidSpecResolutionRequest},
+	}
+	for index, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			db := newRuntimeSpecTestDB(t)
+			taskID := fmt.Sprintf("cg255-reject-%d", index)
+			prepareRuntimeSpecTask(t, db, taskID, test.taskType, test.claimed, `{"color":"黑色","size":"M码"}`)
+			req, _, _ := validRuntimeSpecRequest(t, taskID, "M码", "M码", "L码")
+			if test.mutate != nil {
+				test.mutate(&req)
+			}
+			req.CandidateSnapshotHash = purchaseSpecCandidateSnapshotHash(req)
+			body, _ := json.Marshal(req)
+			key := purchaseSpecIdempotencyKey(taskID, req)
+			_, err := resolvePurchaseSpecWithSnapshotLoader(context.Background(), db, nil, AIEndpointPolicy{},
+				taskID, "CLIENT-255", key, body, func(context.Context, *sql.DB, AISecretStore, AIEndpointPolicy) (AIMatchSnapshot, error) {
+					t.Fatal("权限错误前不应调用 AI")
+					return AIMatchSnapshot{}, nil
+				})
+			if !errors.Is(err, test.expected) {
+				t.Fatalf("err=%v expected=%v", err, test.expected)
+			}
+			var count int
+			if queryErr := db.QueryRow(`SELECT COUNT(*) FROM purchase_spec_resolutions`).Scan(&count); queryErr != nil || count != 0 {
+				t.Fatalf("拒绝请求产生审计记录 count=%d err=%v", count, queryErr)
+			}
+		})
+	}
+}
+
+func TestResolvePurchaseSpec_AI并发重放只产生一个模型调用和一个结论(t *testing.T) {
+	db := newRuntimeSpecTestDB(t)
+	prepareRuntimeSpecTask(t, db, "cg255-ai", model.TaskPurchase, true, `{"color":"黑色","size":"L码"}`)
+	_, body, key := validRuntimeSpecRequest(t, "cg255-ai", "L码", "M码", "XL码")
+	client := &stubAIModelClient{delay: 50 * time.Millisecond,
+		response: AIModelMatchResponse{Conclusion: "match", CandidateID: "c2", ConfidenceBPS: 9300, Reason: "模型唯一匹配"}}
+	loader := func(context.Context, *sql.DB, AISecretStore, AIEndpointPolicy) (AIMatchSnapshot, error) {
+		return AIMatchSnapshot{Provider: model.AIProviderConfig{ProviderID: "provider-1", Model: "model-1",
+			ConfidenceThresholdBPS: 9000}, ConfigFingerprint: "fingerprint", Secret: "secret", Client: client}, nil
+	}
+
+	const workers = 6
+	responses := make(chan string, workers)
+	errorsFound := make(chan error, workers)
+	var wait sync.WaitGroup
+	for range workers {
+		wait.Add(1)
+		go func() {
+			defer wait.Done()
+			response, err := resolvePurchaseSpecWithSnapshotLoader(context.Background(), db, nil, AIEndpointPolicy{},
+				"cg255-ai", "CLIENT-255", key, body, loader)
+			responses <- response
+			errorsFound <- err
+		}()
+	}
+	wait.Wait()
+	close(responses)
+	close(errorsFound)
+	for err := range errorsFound {
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+	first := ""
+	for response := range responses {
+		if first == "" {
+			first = response
+		} else if response != first {
+			t.Fatalf("并发响应不一致: first=%s other=%s", first, response)
+		}
+	}
+	if client.calls.Load() != 1 {
+		t.Fatalf("模型调用次数=%d", client.calls.Load())
+	}
+	var records, finalRecords, idempotency int
+	if err := db.QueryRow(`SELECT COUNT(*),SUM(outcome<>'pending') FROM purchase_spec_resolutions WHERE task_id=?`, "cg255-ai").Scan(&records, &finalRecords); err != nil {
+		t.Fatal(err)
+	}
+	if err := db.QueryRow(`SELECT COUNT(*) FROM idempotency_keys WHERE `+"`key`"+`=?`, key).Scan(&idempotency); err != nil {
+		t.Fatal(err)
+	}
+	if records != 1 || finalRecords != 1 || idempotency != 1 {
+		t.Fatalf("records=%d final=%d idempotency=%d", records, finalRecords, idempotency)
+	}
+}
+
+func TestResolvePurchaseSpec_ShopeeBackfill只作诊断不阻断规则(t *testing.T) {
+	db := newRuntimeSpecTestDB(t)
+	prepareRuntimeSpecTask(t, db, "cg255-backfill", model.TaskPurchase, true, `{"color":"黑色","size":"60公斤"}`)
+	now := model.NowISO()
+	_, err := db.Exec(`INSERT INTO pdd_products
+		(goods_id,url,title,skus_json,collect_status,created_at,updated_at)
+		VALUES(?,?,?,?,'collected',?,?)`, "PDD-255", "https://mobile.yangkeduo.com/goods.html?goods_id=PDD-255",
+		"测试商品", `{"spec_source":"shopee_backfill","skus":[]}`, now, now)
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, body, key := validRuntimeSpecRequest(t, "cg255-backfill", "60公斤", "120斤")
+	response, err := resolvePurchaseSpecWithSnapshotLoader(context.Background(), db, nil, AIEndpointPolicy{},
+		"cg255-backfill", "CLIENT-255", key, body, func(context.Context, *sql.DB, AISecretStore, AIEndpointPolicy) (AIMatchSnapshot, error) {
+			t.Fatal("规则唯一命中不应调用 AI")
+			return AIMatchSnapshot{}, nil
+		})
+	if err != nil {
+		t.Fatal(err)
+	}
+	var parsed PurchaseSpecResolutionResponse
+	if err := json.Unmarshal([]byte(response), &parsed); err != nil || parsed.Outcome != model.PurchaseSpecResolutionMatched {
+		t.Fatalf("response=%s err=%v", response, err)
+	}
+	if !strings.Contains(parsed.Reason, "诊断来源：shopee_backfill") {
+		t.Fatalf("未保存回填规格诊断来源: %+v", parsed)
+	}
+}
+
+func runtimeCandidates(color string, values ...string) []PurchaseSpecCandidate {
+	result := make([]PurchaseSpecCandidate, 0, len(values))
+	for index, value := range values {
+		result = append(result, PurchaseSpecCandidate{CandidateID: fmt.Sprintf("c%d", index+1), RawText: value,
+			Options: map[string]string{"color": color, "size": value}})
+	}
+	return result
+}
+
+func validRuntimeSpecRequest(t *testing.T, taskID, target string, candidates ...string) (PurchaseSpecResolutionRequest, []byte, string) {
+	t.Helper()
+	req := PurchaseSpecResolutionRequest{SchemaVersion: 1, TaskVersion: 1, AttemptID: "attempt-255",
+		PddGoodsID: "PDD-255", OriginalOptions: map[string]string{"color": "黑色", "size": target},
+		SelectedColor: "黑色", TargetSize: target, Candidates: runtimeCandidates("黑色", candidates...),
+		ObservedAt: "2026-08-17T08:00:00Z"}
+	req.CandidateSnapshotHash = purchaseSpecCandidateSnapshotHash(req)
+	body, err := json.Marshal(req)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return req, body, purchaseSpecIdempotencyKey(taskID, req)
+}
+
+func prepareRuntimeSpecTask(t *testing.T, db *sql.DB, taskID string, taskType model.TaskType, claimed bool, options string) {
+	t.Helper()
+	now := model.NowISO()
+	_, err := db.Exec(`INSERT INTO clients
+		(client_id,name,device_address,platform,pdd_package,capabilities,last_seen_at,created_at,updated_at)
+		VALUES('CLIENT-255','测试客户端','','android','','{}',?,?,?)`, now, now, now)
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = db.Exec(`INSERT INTO tasks
+		(task_id,task_type,status,version,assigned_client,goods_id,pdd_goods_url,pdd_goods_id,pdd_options,
+		 quantity,max_price_cent,created_at,updated_at)
+		VALUES(?,?,?,1,'CLIENT-255','SHOPEE-255',?,?,?,1,2000,?,?)`, taskID, taskType, model.TaskClaimed,
+		"https://mobile.yangkeduo.com/goods.html?goods_id=PDD-255", "PDD-255", options, now, now)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if claimed {
+		if _, err := db.Exec(`INSERT INTO task_claims(task_id,client_id,claimed_at) VALUES(?,?,?)`,
+			taskID, "CLIENT-255", now); err != nil {
+			t.Fatal(err)
+		}
+	}
+}
+
+// newRuntimeSpecTestDB 默认使用历史 SQLite 测试库跑服务编排；显式打开 MySQL 测试时
+// 自动切到隔离的 MySQL 8 数据库。生产代码仍只运行在 MySQL。
+func newRuntimeSpecTestDB(t *testing.T) *sql.DB {
+	t.Helper()
+	if os.Getenv("CMAUTOBUY_MYSQL_TEST") == "1" {
+		return newTestDB(t)
+	}
+	db, err := repository.Open(t.TempDir())
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() { db.Close() })
+	if err := repository.Migrate(db); err != nil {
+		t.Fatal(err)
+	}
+	_, err = db.Exec(`CREATE TABLE purchase_spec_resolutions (
+		resolution_id TEXT PRIMARY KEY,task_id TEXT NOT NULL,attempt_id TEXT NOT NULL,client_id TEXT NOT NULL,
+		task_version INTEGER NOT NULL,pdd_goods_id TEXT NOT NULL,original_options_json TEXT NOT NULL,
+		selected_color TEXT NOT NULL,target_size TEXT NOT NULL,candidates_json TEXT NOT NULL,
+		candidate_snapshot_hash TEXT NOT NULL,request_hash TEXT NOT NULL,observed_at TEXT NOT NULL,
+		outcome TEXT NOT NULL DEFAULT 'pending',decision_source TEXT,chosen_candidate_id TEXT,
+		resolved_options_json TEXT,confidence_bps INTEGER,reason TEXT,provider_id TEXT,source_model TEXT,
+		config_fingerprint TEXT,rules_version TEXT,prompt_version TEXT,created_at TEXT NOT NULL,decided_at TEXT,
+		UNIQUE(task_id,attempt_id,candidate_snapshot_hash)
+	)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return db
+}
diff --git a/docs/admin/01-requirements.md b/docs/admin/01-requirements.md
index 98623b3..d2e8d7c 100644
--- a/docs/admin/01-requirements.md
+++ b/docs/admin/01-requirements.md
@@ -415,6 +415,32 @@ Admin 本地时区，付款状态只是 Client 核单上报时的快照，Admin
 - “AI规格匹配”是当前有效映射的来源筛选，不替代“可创建采购任务”等业务阶段。人工修改后
   当前来源立即变为人工，但历史 AI 决策和批次记录继续保留。
 
+### 4.7 采购运行时真机规格解析（#255）
+
+采购任务已经在 Client 上选定颜色，但任务目标尺码和当前 PDD 页面文字无法精确对应时，
+Client 可以把这一刻页面显示的可购买尺码提交给 Admin 做一次解析。该能力只用于解决
+“任务规格与真机候选文字不一致”，不会改变正常精确匹配流程。
+
+- Admin 必须先核对采购任务、任务版本、PDD 商品、任务原始规格和该 Client 的领取历史；
+  任一身份不一致都拒绝，并且不产生解析决策。
+- 候选编号、原文、颜色和尺码由 Client 按页面顺序固定。Admin 重新计算候选快照哈希，
+  AI 只能选择本次请求内的候选短编号，不能生成或改写 PDD 规格。
+- 先执行确定性规则：忽略大小写、空白和分隔符，处理已明确的繁简差异，并支持唯一的
+  `kg / 公斤 / 千克 / 斤` 单值或正向区间等价。只有唯一候选等价时才自动返回；多个等价、
+  倒序或多个候选同时重叠时直接返回 `uncertain`，不交给 AI 猜一个。
+- 规则没有唯一结论时才使用当前已启用且通过连接测试的 AI 配置；模型结论仍须通过候选
+  白名单、冲突/缺失维度和管理员置信度阈值门禁。模型超时、格式错误或越权候选都形成
+  可审计结论，不把模型输出直接写进任务。
+- `pdd_products.skus_json.spec_source=shopee_backfill` 只用于诊断规格来源，既不自动触发 AI，
+  也不拒绝本次解析；是否需要解析只由真机候选和任务目标能否唯一对应决定。
+- 相同任务、执行尝试和候选快照幂等重放时返回第一次的完整响应；并发相同请求只完成一条
+  最终决策。候选观察与最终决策分两个短事务，调用模型期间不持有数据库事务。
+- 解析记录是只追加的运行审计。它不得修改 `tasks` 状态、版本、目标规格、价格、
+  `task_runs.irreversible_action_at` 或 `pdd_products.skus_json`，也不得保存控件树、截图、订单、
+  收货信息、Cookie、Token 或 API Key。
+- Admin 返回候选后，Client 仍须重新读取页面并继续执行商品、规格、数量、总价、地址、
+  不可逆标记和单次提交门禁；运行时解析不能绕过任何真实下单安全检查。
+
 ## 5. 创建采购任务的校验
 
 `[必须]` 下面任何一条不满足就不允许创建，并明确告诉操作员缺什么：
diff --git a/docs/admin/02-architecture.md b/docs/admin/02-architecture.md
index 8892de8..19dc713 100644
--- a/docs/admin/02-architecture.md
+++ b/docs/admin/02-architecture.md
@@ -248,6 +248,8 @@ handler 返回批次 JSON；管理员在统一导入记录页查看摘要
 - Admin 是任务的创建者和分配者，Client 是执行者。
 - Admin **不知道** Client 执行到哪一步（没有心跳，是有意的）。
 - Client 提交结果时，Admin **无条件接受**，哪怕任务已取消或已重派。
+- Client 的运行时规格解析是 `POST /api/v1/client/tasks/{task_id}/spec-resolution` 一次性命令，
+  不是任务状态查询或轮询；权威字段、哈希和错误码仍以 Client 侧契约 §7.1 为准。
 - Admin 用户登录与 Client 身份是两套边界。Web Session 不传给 Client，
   Web 登录中间件也不覆盖 `/api/v1/client/*`。
 - 详见 [04 Client 接口实现](04-client-api.md)。
@@ -269,6 +271,21 @@ URL 内凭据、环回、链路本地、云元数据和未显式允许的私网
 唯一确定的规则结果不调用模型；有效人工映射始终优先。保存前重新计算上下文版本并检查
 当前可购买候选，防止 PDD 重采集或人工并发修改后写入过期结果。
 
+采购运行时规格解析复用同一个 `AISecretStore`、端点策略、HTTP 客户端、超时、响应结构
+校验和置信度阈值，但不复用 SYB 映射写入路径。Handler 只限制 64 KiB 请求体并翻译稳定
+错误码；`service/purchase_spec_resolution.go` 负责请求/哈希/任务身份校验、规则优先和 AI
+候选白名单；`repository/purchase_spec_resolution.go` 只保存观察和最终决策。
+
+一次解析分成以下三个边界：
+
+1. 短事务核对任务和领取历史，写入 `purchase_spec_resolutions.outcome=pending` 候选观察；
+2. 事务外执行确定性规则或调用模型，同一进程内相同幂等身份串行，避免并发重复调用；
+3. 短事务把 `pending` 完成一次，并与 `idempotency_keys` 的完整响应一起提交。
+
+服务中断后留下的 `pending` 可以由原幂等请求接管；最终 SQL 仍只允许第一次从 `pending`
+完成。响应中的 `match` 必须从保存的请求候选逐字重建。此链路不更新任务、PDD 商品和
+下单执行状态；`shopee_backfill` 只保留为来源诊断信号，不参与启用或拒绝判断。
+
 批量入口先在事务中创建 `ai_match_batches` 和逐条 `ai_match_batch_items`，再由 Admin 进程内
 的有界工作池执行。工作池按业务上下文哈希归并相同明细，运行中持续写入逐条状态和汇总计数；
 浏览器只轮询批次状态接口，不持有 API Key，也不承担匹配判断。Admin 启动时把遗留的