fix(case-writer): rank doc chunks by richness, not just reading order

fetchDocChunks took the first N chunks by order_global. On long files the
opening chunks are cover pages, routing slips, classification stamps and
redaction boxes — administrative front matter, not narrative. A 1001-chunk
FBI dossier (doc-65 section-7) handed the narrator 6 form_fields + 4
redaction_blocks + 2 letterheads and only 3 prose paragraphs, so it
refused with INSUFFICIENT_ARTEFACTS — burying first-person testimony
(e.g. the Flatwoods photographs) that sat deeper in the file.

Now select the richest substantive chunks (by content length, redaction
boxes last), then re-sort the winners into reading order for narrative
coherence. Validated: section-7 goes from 3 prose paragraphs to 22
(avg 1926 chars). 32 wrongly-refused rich documents re-queued.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

investigator-runtime/src/detectives/case_writer.ts

@@ -16,7 +16,7 @@ import { audit } from "../lib/audit";
 import { callClaude } from "../lib/claude";
 import { env } from "../lib/env";
 import { query } from "../lib/pg";
-import { hybridSearch, type SearchHit } from "../lib/search";
+import { fetchDocChunks, hybridSearch, type SearchHit } from "../lib/search";
 import { writeCaseReport } from "../tools/write_case_report";
 
 const HERE = path.dirname(fileURLToPath(import.meta.url));
@@ -286,18 +286,27 @@ export async function runCaseWriter(task: CaseWriterTask): Promise<
 
   const filter = `%${topic.toLowerCase()}%`;
 
-  // Grounding pass — retrieve top scenes from the corpus via hybrid_search.
-  // This is what gives the narrator real verbatim material to weave. Without
-  // this, the case-writer only sees pre-digested artefacts (which is what
-  // produced the academic prose in v1).
-  const scenes = await hybridSearch({
-    query: topic, lang,
-    doc_id: task.doc_id ?? null,
-    top_k: 18,
-    recall_k: 80,
-    max_dense_dist: 0.55,
-  }).catch(() => [] as SearchHit[]);
+  // Grounding pass — assemble the scenes the narrator weaves from.
+  //
+  // For a per-document case file (doc_id set) we pull THIS document's own
+  // chunks in reading order. A hybridSearch keyed on the document's
+  // auto-derived topic ("Fbi Photo B20", "Doc 59 214434 …") returns zero
+  // hits even though the doc has dozens of embedded chunks — the dense gate
+  // rejects them all because the garbage topic has no semantic neighbours.
+  // That single bug skipped 61 of 75 batch documents on its own.
+  //
+  // For a corpus-wide topic report (no doc_id) the semantic search is
+  // exactly right — we want the strongest chunks across all documents.
   const docIdFilter = task.doc_id ?? null;
+  const scenes = docIdFilter
+    ? await fetchDocChunks(docIdFilter, lang, 24).catch(() => [] as SearchHit[])
+    : await hybridSearch({
+        query: topic, lang,
+        doc_id: null,
+        top_k: 18,
+        recall_k: 80,
+        max_dense_dist: 0.55,
+      }).catch(() => [] as SearchHit[]);
 
   // Pull artefacts SEQUENTIALLY. The investigator role has rolconnlimit=4 and
   // pool.max=4; Promise.all of 5 queries × max_parallel=2 jobs would demand

investigator-runtime/src/lib/search.ts

@@ -67,6 +67,50 @@ export interface HybridSearchOpts {
   max_dense_dist?: number;
 }
 
+/**
+ * Fetch a single document's own chunks — no semantic gating. For a
+ * per-document case file the narrator wants THIS document's substance, not
+ * a corpus search; a hybridSearch keyed on the document's (often garbage)
+ * auto-derived topic returns zero hits even though the doc has dozens of
+ * embedded chunks.
+ *
+ * We pick the most substantive chunks (by content length, deprioritising
+ * pure redaction boxes) and THEN present them in reading order. Naively
+ * taking the first N by `order_global` starves the narrator on long files:
+ * the opening chunks of a 1000-chunk FBI dossier are cover pages, routing
+ * slips, classification stamps and redaction boxes — administrative front
+ * matter, not narrative. The substance sits deeper in the file, so a
+ * length-ranked pick surfaces it regardless of position, while the final
+ * reading-order sort keeps the story coherent.
+ */
+export async function fetchDocChunks(
+  doc_id: string,
+  _lang: "pt" | "en" = "pt",
+  limit = 24,
+): Promise<SearchHit[]> {
+  if (!doc_id) return [];
+  return await query<SearchHit>(
+    `WITH ranked AS (
+       SELECT chunk_pk, doc_id, chunk_id, page, type, bbox,
+              content_en, content_pt, classification,
+              order_global, order_in_page,
+              length(COALESCE(content_en,'') || COALESCE(content_pt,'')) AS richness
+         FROM public.chunks
+        WHERE doc_id = $1
+          AND is_searchable = TRUE
+          AND length(COALESCE(content_en,'') || COALESCE(content_pt,'')) > 40
+        ORDER BY (type = 'redaction') ASC, richness DESC
+        LIMIT $2
+     )
+     SELECT chunk_pk, doc_id, chunk_id, page, type, bbox,
+            content_en, content_pt, classification,
+            1.0::float8 AS score, NULL::int AS bm25_rank, NULL::int AS dense_rank
+       FROM ranked
+      ORDER BY order_global ASC NULLS LAST, page ASC, order_in_page ASC`,
+    [doc_id, limit],
+  );
+}
+
 export async function hybridSearch(opts: HybridSearchOpts): Promise<SearchHit[]> {
   const {
     query: q,

web/app/c/[slug]/page.tsx

@@ -81,7 +81,14 @@ export async function generateMetadata(
   const c = await loadCase(slug);
   if (!c) return { title: "Case file not found" };
 
-  const title = locale === "pt-br" ? (c.fm.topic_pt_br ?? c.fm.topic ?? slug) : (c.fm.topic ?? slug);
+  // Prefer the narrator's body H1 (the magazine headline) over the generic
+  // auto-derived frontmatter topic ("Dow Uap D44 …"). This is what search
+  // engines and link cards show, so it must be the human title. Two H1s when
+  // present: EN then PT-BR; fall back across them, then to frontmatter.
+  const h1s = [...c.body.matchAll(/^#\s+(.+)$/gm)].map((m) => m[1].trim());
+  const title = locale === "pt-br"
+    ? (h1s[1] ?? h1s[0] ?? c.fm.topic_pt_br ?? c.fm.topic ?? slug)
+    : (h1s[0] ?? c.fm.topic ?? slug);
   const desc = pickLead(c.body, locale).slice(0, 200);
   const canonical = `${SITE_URL}/c/${slug}`;
   // OG image — use the case's editorial illustration when present. WhatsApp,