feat(tenant): guard numeric knowledge facts against silent contradiction

Ensure numeric facts present in retrieved knowledge (especially company
founding dates) cannot be silently contradicted in generated articles.

- Add a typed fact guard that extracts constraints (dates, experience
  years, etc.) from precise facts, detects source conflicts, and
  validates generated content before persistence with a bounded repair
  retry.
- Surface fact constraints through KnowledgeContext and render them as
  a canonical, non-derivable fact block in the knowledge prompt section.
- Tighten prompt intro lines to forbid rewriting, mixing old values,
  or deriving service years from founding dates.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server/internal/tenant/app/knowledge_service.go

@@ -131,10 +131,12 @@ type KnowledgeURLItemRequest struct {
 }
 
 type KnowledgeContext struct {
-	GroupIDs     []int64
-	GroupNames   []string
-	Snippets     []KnowledgeSnippet
-	PreciseFacts []string
+	GroupIDs        []int64
+	GroupNames      []string
+	Snippets        []KnowledgeSnippet
+	PreciseFacts    []string
+	FactConstraints []KnowledgeFactConstraint
+	FactConflicts   []KnowledgeFactConflict
 }
 
 type KnowledgeSnippet struct {
@@ -936,6 +938,7 @@ func (s *KnowledgeService) ResolveContext(
 		Snippets:     []KnowledgeSnippet{},
 		PreciseFacts: s.collectKnowledgeContextPreciseFacts(ctx, tenantID, brandID, searchGroupIDs, nil),
 	}
+	s.applyKnowledgeFactConstraints(baseContext)
 
 	vectors, err := s.provider.Embed(ctx, queries)
 	if err != nil {
@@ -994,6 +997,7 @@ func (s *KnowledgeService) ResolveContext(
 		selected = s.enrichKnowledgePromptSnippets(ctx, tenantID, brandID, selected)
 		baseContext.Snippets = selected
 		baseContext.PreciseFacts = s.collectKnowledgeContextPreciseFacts(ctx, tenantID, brandID, searchGroupIDs, selected)
+		s.applyKnowledgeFactConstraints(baseContext)
 		s.logKnowledgeResolve(baseContext, tenantID, rerankQuery, "rerank_failed_fallback", queryRewriteStage, queryRewriteModel, candidates, selected)
 		return baseContext, nil
 	}
@@ -1002,6 +1006,7 @@ func (s *KnowledgeService) ResolveContext(
 	selected = s.enrichKnowledgePromptSnippets(ctx, tenantID, brandID, selected)
 	baseContext.Snippets = selected
 	baseContext.PreciseFacts = s.collectKnowledgeContextPreciseFacts(ctx, tenantID, brandID, searchGroupIDs, selected)
+	s.applyKnowledgeFactConstraints(baseContext)
 	s.logKnowledgeResolve(baseContext, tenantID, rerankQuery, "resolved", queryRewriteStage, queryRewriteModel, candidates, selected)
 	return baseContext, nil
 }
@@ -1348,7 +1353,7 @@ func normalizeKnowledgeSnippetTextKey(text string) string {
 }
 
 func (s *KnowledgeService) RenderPromptSection(ctx *KnowledgeContext) string {
-	if ctx == nil || (len(ctx.Snippets) == 0 && len(ctx.PreciseFacts) == 0) {
+	if ctx == nil || (len(ctx.Snippets) == 0 && len(ctx.PreciseFacts) == 0 && len(ctx.FactConstraints) == 0) {
 		return ""
 	}
 
@@ -1357,6 +1362,21 @@ func (s *KnowledgeService) RenderPromptSection(ctx *KnowledgeContext) string {
 	if len(preciseFacts) == 0 {
 		preciseFacts = collectKnowledgePromptPreciseFacts(ctx.Snippets)
 	}
+	factConstraints := ctx.FactConstraints
+	if len(factConstraints) == 0 {
+		var conflicts []KnowledgeFactConflict
+		factConstraints, conflicts = buildKnowledgeFactConstraints(preciseFacts)
+		preciseFacts = removeConflictingKnowledgeFacts(preciseFacts, conflicts)
+	}
+	if len(factConstraints) > 0 {
+		lines = append(lines,
+			"以下为系统落库前会自动校验的规范事实；涉及对应主体时只能使用这些值，不得引用旧版本、推算年限或自行补充数字：",
+		)
+		for _, constraint := range factConstraints {
+			lines = append(lines, "- "+renderKnowledgeFactConstraint(constraint))
+		}
+		lines = append(lines, "")
+	}
 	if len(preciseFacts) > 0 {
 		lines = append(lines,
 			"以下为必须严格按原文保留的高精度事实；如果正文需要引用，必须逐字一致，不得改写、翻译、推测或补全：",
@@ -1379,6 +1399,27 @@ func (s *KnowledgeService) RenderPromptSection(ctx *KnowledgeContext) string {
 	return strings.Join(lines, "\n")
 }
 
+func (s *KnowledgeService) applyKnowledgeFactConstraints(ctx *KnowledgeContext) {
+	if ctx == nil {
+		return
+	}
+	constraints, conflicts := buildKnowledgeFactConstraints(ctx.PreciseFacts)
+	ctx.PreciseFacts = removeConflictingKnowledgeFacts(ctx.PreciseFacts, conflicts)
+	ctx.FactConstraints = constraints
+	ctx.FactConflicts = conflicts
+	if s == nil || s.logger == nil {
+		return
+	}
+	for _, conflict := range conflicts {
+		s.logger.Warn("knowledge fact source conflict",
+			zap.String("fact_kind", string(conflict.Kind)),
+			zap.String("fact_subject", conflict.Subject),
+			zap.String("canonical_value", conflict.CanonicalValue),
+			zap.String("conflicting_value", conflict.ConflictingValue),
+		)
+	}
+}
+
 type knowledgePromptItemRecord struct {
 	ID              int64
 	GroupID         int64
@@ -1601,11 +1642,11 @@ func (s *KnowledgeService) loadKnowledgePromptItemsByGroupIDs(
 		  AND ki.deleted_at IS NULL
 		  AND ki.group_id IN (SELECT id FROM selected_groups)
 		ORDER BY
+		  ki.updated_at DESC,
 		  CASE
 		    WHEN ki.id = ANY($4::bigint[]) THEN 0
 		    ELSE 1
 		  END,
-		  ki.updated_at DESC,
 		  ki.id DESC
 		LIMIT $5
 	`, tenantID, brandID, groupIDs, prioritizedItemIDs, limit)
@@ -1783,7 +1824,9 @@ func knowledgePreciseFactLabelOnly(line string) bool {
 		"主营业务", "主要业务", "核心业务", "业务范围", "经营范围", "服务范围",
 		"主营产品", "主要产品", "核心产品", "产品范围",
 		"main business", "core business", "business scope", "service scope",
-		"main products", "core products", "product scope":
+		"main products", "core products", "product scope",
+		"成立时间", "创立时间", "创办时间", "创建时间", "注册时间", "注册成立时间",
+		"服务年限", "行业经验", "从业经验", "经营年限", "company founded", "founded", "established":
 		return true
 	default:
 		return false
@@ -1808,6 +1851,9 @@ func knowledgeLineContainsPreciseFact(line string) bool {
 		"opening hours", "business hours", "postcode", "zip code",
 		"main business", "core business", "business scope", "service scope",
 		"main products", "core products", "product scope",
+		"成立于", "成立时间", "创立于", "创立时间", "创办于", "创办时间", "创建于", "创建时间", "注册成立", "注册时间",
+		"服务经验", "行业经验", "从业经验", "经营经验", "经营年限", "深耕",
+		"founded", "established", "years of experience",
 	}
 	for _, keyword := range keywords {
 		if strings.Contains(lower, keyword) {
@@ -1853,6 +1899,9 @@ func knowledgeLineStartsAnotherPreciseFact(line string) bool {
 		"opening hours:", "business hours:",
 		"main business:", "core business:", "business scope:", "service scope:",
 		"main products:", "core products:", "product scope:",
+		"成立时间：", "创立时间：", "创办时间：", "创建时间：", "注册时间：", "注册成立时间：",
+		"服务年限：", "行业经验：", "从业经验：", "经营年限：",
+		"company founded:", "founded:", "established:",
 	}
 	for _, label := range labels {
 		if strings.HasPrefix(lower, label) {