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/template_service.go

@@ -287,6 +287,10 @@ func (s *TemplateService) Generate(ctx context.Context, templateID int64, req Ge
 	if err := s.llm.Validate(); err != nil {
 		return nil, response.ErrServiceUnavailable(50311, "llm_unavailable", err.Error())
 	}
+	brandPromptContext, err := loadBrandPromptContext(ctx, s.pool, actor.TenantID, brandID)
+	if err != nil {
+		return nil, err
+	}
 
 	initialTitle := resolveArticleTitle(req.InputParams, "")
 	wizardStateJSON, err := json.Marshal(normalizeWizardState(req.WizardState, wizardStateCurrentStep(req.WizardState)))
@@ -300,11 +304,13 @@ func (s *TemplateService) Generate(ctx context.Context, templateID int64, req Ge
 	}
 
 	taskInputParams := cloneInputParams(req.InputParams)
+	taskInputParams["brand_id"] = brandID
 	taskInputParams["enable_web_search"] = req.EnableWebSearch
 	if req.WebSearchLimit != nil {
 		taskInputParams["web_search_limit"] = *req.WebSearchLimit
 	}
 	taskInputParams = attachTemplateSnapshot(taskInputParams, templateRecord)
+	taskInputParams = attachBrandPromptContext(taskInputParams, brandPromptContext)
 	inputJSON, _ := json.Marshal(taskInputParams)
 
 	tx, err := s.pool.Begin(ctx)
@@ -480,8 +486,16 @@ func (s *TemplateService) executeGeneration(ctx context.Context, job generationJ
 	}
 	RecordGenerationTaskEvent(GenerationTaskEventTransition, generationJobLogContext(job, "task_status_running", "", GenerationTaskStatusRunning, GenerationTaskResultSuccess))
 	LogGenerationTaskInfo(s.logger, "article generation task marked running", generationJobLogContext(job, "task_status_running", "", GenerationTaskStatusRunning, GenerationTaskResultSuccess))
+	brandID, brandPromptContext, err := ResolveGenerationBrandPromptContext(ctx, s.pool, job.TenantID, job.ArticleID, job.Params)
+	if err != nil {
+		s.failGeneration(ctx, job, title, "brand_context_load", err)
+		return
+	}
+	job.Params["brand_id"] = brandID
+	job.Params = attachBrandPromptContext(job.Params, brandPromptContext)
 
 	knowledgePrompt := ""
+	var knowledgeFactConstraints []KnowledgeFactConstraint
 	if knowledgeGroupIDs := extractKnowledgeGroupIDs(job.Params["knowledge_group_ids"]); len(knowledgeGroupIDs) > 0 {
 		if s.knowledge == nil {
 			s.failGeneration(ctx, job, title, "knowledge_resolve", fmt.Errorf("knowledge service is not configured"))
@@ -490,7 +504,7 @@ func (s *TemplateService) executeGeneration(ctx context.Context, job generationJ
 		knowledgeContext, resolveErr := s.knowledge.ResolveContext(
 			ctx,
 			job.TenantID,
-			int64(extractInt(job.Params, "brand_id")),
+			brandID,
 			knowledgeGroupIDs,
 			buildGenerationKnowledgeQuery(job.TemplateKey, job.TemplateName, job.Params),
 		)
@@ -499,6 +513,7 @@ func (s *TemplateService) executeGeneration(ctx context.Context, job generationJ
 			return
 		}
 		knowledgePrompt = s.knowledge.RenderPromptSection(knowledgeContext)
+		knowledgeFactConstraints = knowledgeContext.FactConstraints
 	}
 
 	prompt := buildGenerationPrompt(job.TemplateKey, job.TemplateName, job.PromptTemplate, job.Params, knowledgePrompt)
@@ -511,7 +526,8 @@ func (s *TemplateService) executeGeneration(ctx context.Context, job generationJ
 	if job.WebSearch.Enabled {
 		generateReq.WebSearch = &job.WebSearch
 	}
-	result, err := s.llm.Generate(ctx, generateReq, func(delta string) {
+	knowledgeFactConstraints = MergeKnowledgeFactConstraints(brandPromptContext.FactConstraints, knowledgeFactConstraints)
+	result, err := GenerateArticleWithKnowledgeFactGuard(ctx, s.llm, generateReq, knowledgeFactConstraints, func(delta string) {
 		if runtimeCfg.StreamEnabled && delta != "" {
 			s.streams.AppendDelta(job.ArticleID, job.TaskID, title, delta)
 		}