fix(pipeline): skip RawPages with empty title in BuildPages instead of producing broken paths

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ingestion/internal/pipeline/build.go

@@ -10,13 +10,27 @@ import (
 
 // BuildPages converts RawPages from the LLM into wiki.Pages with computed slugs,
 // paths, and YAML frontmatter. sourceSlug is the slug of the source being ingested
-// (derived from the filename, not the LLM title).
-func BuildPages(rawPages []RawPage, sourceSlug, date string) []wiki.Page {
+// (derived from the filename, not the LLM title). Pages whose title resolves to an
+// empty slug are skipped and returned as warnings instead.
+func BuildPages(rawPages []RawPage, sourceSlug, date string) ([]wiki.Page, []string) {
 	out := make([]wiki.Page, 0, len(rawPages))
+	var warnings []string
 	for _, rp := range rawPages {
+		slug := computeSlug(rp, sourceSlug)
+		if slug == "" {
+			warnings = append(warnings, fmt.Sprintf("skipped page with empty title (type: %s)", rp.Type))
+			continue
+		}
 		out = append(out, buildPage(rp, sourceSlug, date))
 	}
-	return out
+	return out, warnings
+}
+
+func computeSlug(rp RawPage, sourceSlug string) string {
+	if rp.Type == "source" {
+		return sourceSlug
+	}
+	return wiki.Slug(rp.Title)
 }
 
 func buildPage(rp RawPage, sourceSlug, date string) wiki.Page {