feat(tenant): inject brand description context into every generation path

Include the current brand description in template, custom, imitation,
and KOL article-generation prompts while bounding prompt growth.

- Add a shared brand-context builder that resolves the current brand,
  compacts long descriptions, and caps rendered output at 2000 runes.
- Snapshot a structured brand prompt context on queued tasks so old
  jobs stay reproducible and retries stay stable.
- Route brand-profile facts through the existing typed fact guard so
  founding dates and year counts get the same pre-persistence validation
  as RAG facts, with brand facts outranking conflicting RAG facts.
- Fix the KOL creator to attach the brand scope its worker consumes.

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

server/internal/tenant/app/prompt_generate_service.go

@@ -39,15 +39,16 @@ type PromptRuleGenerationService struct {
 }
 
 type promptRuleGenerationJob struct {
-	OperatorID    int64
-	TenantID      int64
-	ArticleID     int64
-	TaskID        int64
-	ReservationID int64
-	Prompt        string
-	InputParams   map[string]interface{}
-	InitialTitle  string
-	WebSearch     llm.WebSearchOptions
+	OperatorID               int64
+	TenantID                 int64
+	ArticleID                int64
+	TaskID                   int64
+	ReservationID            int64
+	Prompt                   string
+	InputParams              map[string]interface{}
+	InitialTitle             string
+	WebSearch                llm.WebSearchOptions
+	KnowledgeFactConstraints []KnowledgeFactConstraint
 }
 
 type GenerateFromRuleRequest struct {
@@ -282,6 +283,10 @@ func (s *PromptRuleGenerationService) enqueuePromptRuleGeneration(ctx context.Co
 	if rule.Status != "enabled" {
 		return nil, response.ErrBadRequest(40017, "prompt_rule_disabled", "prompt rule is disabled")
 	}
+	brandPromptContext, err := loadBrandPromptContext(ctx, s.pool, input.TenantID, *input.BrandID)
+	if err != nil {
+		return nil, err
+	}
 
 	extra := input.ExtraParams
 	generationMode := strings.TrimSpace(extractString(extra, "generation_mode"))
@@ -346,6 +351,7 @@ func (s *PromptRuleGenerationService) enqueuePromptRuleGeneration(ctx context.Co
 		inputParams["knowledge_group_ids"] = rule.KnowledgeGroupIDs
 	}
 	inputParams = attachPromptRuleSnapshot(inputParams, rule)
+	inputParams = attachBrandPromptContext(inputParams, brandPromptContext)
 
 	knowledgePrompt := ""
 	if len(rule.KnowledgeGroupIDs) > 0 {
@@ -363,6 +369,7 @@ func (s *PromptRuleGenerationService) enqueuePromptRuleGeneration(ctx context.Co
 			return nil, resolveErr
 		}
 		knowledgePrompt = s.knowledge.RenderPromptSection(knowledgeContext)
+		inputParams = attachKnowledgeFactConstraints(inputParams, knowledgeContext.FactConstraints)
 		if knowledgePrompt != "" {
 			inputParams[generationPayloadKnowledgePrompt] = knowledgePrompt
 		}
@@ -559,7 +566,7 @@ func (s *PromptRuleGenerationService) executeGeneration(ctx context.Context, job
 		req.WebSearch = &job.WebSearch
 	}
 
-	result, err := s.llm.Generate(ctx, req, func(delta string) {
+	result, err := GenerateArticleWithKnowledgeFactGuard(ctx, s.llm, req, job.KnowledgeFactConstraints, func(delta string) {
 		if runtimeCfg.StreamEnabled && s.streams != nil && delta != "" {
 			s.streams.AppendDelta(job.ArticleID, job.TaskID, title, delta)
 		}
@@ -838,6 +845,9 @@ func buildPromptRuleGenerationPrompt(rule *promptRuleGenerationRecord, params ma
 	if len(supplements) > 0 {
 		sections = append(sections, prompts.PromptRuleSupplementSection(supplements))
 	}
+	if brandPrompt := RenderBrandPromptContext(extractBrandPromptContext(params)); brandPrompt != "" {
+		sections = append(sections, brandPrompt)
+	}
 
 	if strings.TrimSpace(knowledgePrompt) != "" {
 		sections = append(sections, knowledgePrompt)