feat(workers): extract.pdf with Tesseract fallback

pdftotext first; falls back to per-page pdftoppm rasterization +
Tesseract OCR when the extracted text is < 200 chars. Updates
refs.body_text + metadata.extract.{method,chars} via the repo shim;
audit entry emitted with actor_kind='worker'.

born_digital.pdf fixture padded so pdftotext yields > 200 chars and
the test exercises the pdftotext path, not the OCR fallback.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

workers/void_workers/handlers/__init__.py

@@ -1,5 +1,6 @@
-from . import echo
+from . import echo, pdf
 
 REGISTRY = {
     echo.NAME: echo.handle,
+    pdf.NAME: pdf.handle,
 }

workers/void_workers/handlers/pdf.py

@@ -0,0 +1,47 @@
+import subprocess
+import tempfile
+from pathlib import Path
+from PIL import Image
+import pytesseract
+from .. import repo
+
+NAME = "extract.pdf"
+FALLBACK_THRESHOLD = 200  # chars below which we OCR
+
+
+def _pdftotext(blob_path):
+    return subprocess.check_output(
+        ["pdftotext", "-layout", blob_path, "-"], timeout=120
+    ).decode("utf-8", errors="replace")
+
+
+def _ocr_pdf(blob_path):
+    """Rasterize each page with pdftoppm, OCR each with Tesseract."""
+    with tempfile.TemporaryDirectory() as tmp:
+        subprocess.run(
+            ["pdftoppm", "-r", "200", "-png", blob_path, f"{tmp}/p"],
+            check=True, timeout=300
+        )
+        pages = sorted(Path(tmp).glob("p-*.png"))
+        parts = []
+        for p in pages:
+            img = Image.open(p)
+            parts.append(pytesseract.image_to_string(img, lang="eng"))
+        return "\n".join(parts)
+
+
+def handle(job_data: dict) -> dict:
+    ref_id = job_data["ref_id"]
+    blob_path = job_data["blob_path"]
+    method = "pdftotext"
+    text = _pdftotext(blob_path).strip()
+    if len(text) < FALLBACK_THRESHOLD:
+        method = "tesseract"
+        text = _ocr_pdf(blob_path).strip()
+    body_text = text[:200_000]
+    repo.update_ref(
+        ref_id,
+        body_text=body_text,
+        metadata_patch={"extract": {"method": method, "chars": len(body_text)}}
+    )
+    return {"ref_id": ref_id, "chars": len(body_text), "method": method}

workers/void_workers/repo.py

@@ -0,0 +1,99 @@
+import json
+import psycopg
+from psycopg.rows import dict_row
+from .config import DATABASE_URL
+
+
+def _conn():
+    return psycopg.connect(
+        DATABASE_URL, autocommit=True, row_factory=dict_row, client_encoding='UTF8'
+    )
+
+
+def _maybe_json(v):
+    return json.dumps(v) if isinstance(v, (dict, list)) else v
+
+
+def update_ref(ref_id, *, body_text=None, metadata_patch=None):
+    """UPDATE refs ... and emit an audit_log row with actor_kind='worker'."""
+    with _conn() as conn:
+        before = conn.execute("SELECT * FROM refs WHERE id=%s", (ref_id,)).fetchone()
+        sets, args = [], []
+        if body_text is not None:
+            sets.append("body_text=%s"); args.append(body_text)
+        if metadata_patch is not None:
+            sets.append("metadata = coalesce(metadata, '{}'::jsonb) || %s::jsonb")
+            args.append(json.dumps(metadata_patch))
+        if not sets:
+            return before
+        sets.append("updated_at=now()")
+        args.append(ref_id)
+        after = conn.execute(
+            f"UPDATE refs SET {', '.join(sets)} WHERE id=%s RETURNING *",
+            args
+        ).fetchone()
+        diff = {}
+        if body_text is not None and (before or {}).get("body_text") != body_text:
+            diff["body_text"] = {"before_len": len((before or {}).get("body_text") or ""),
+                                 "after_len": len(body_text)}
+        conn.execute("""
+          INSERT INTO audit_log(actor_kind, actor_id, entity_type, entity_id, action, diff)
+          VALUES('worker', NULL, 'ref', %s, 'update', %s)
+        """, (ref_id, json.dumps({"kind": "update", "changes": diff})))
+        return after
+
+
+def create_ref(input_):
+    """INSERT INTO refs(...) RETURNING id; emit an audit_log row."""
+    fields = ["space_id", "kind", "source_url", "title", "summary", "body_text",
+              "blob_path", "metadata", "source_kind", "external_id", "captured_at"]
+    cols, vals = [], []
+    for f in fields:
+        if f in input_:
+            cols.append(f)
+            vals.append(_maybe_json(input_[f]))
+    placeholders = ",".join("%s" for _ in cols)
+    sql = f"INSERT INTO refs({','.join(cols)}) VALUES({placeholders}) RETURNING id"
+    with _conn() as conn:
+        ref_id = conn.execute(sql, vals).fetchone()["id"]
+        conn.execute("""
+          INSERT INTO audit_log(actor_kind, actor_id, entity_type, entity_id, action, diff)
+          VALUES('worker', NULL, 'ref', %s, 'create', %s)
+        """, (ref_id, json.dumps({"kind": "create"})))
+        return str(ref_id)
+
+
+def get_source_doc(source_doc_id):
+    with _conn() as conn:
+        return conn.execute(
+            "SELECT * FROM source_docs WHERE id=%s", (source_doc_id,)
+        ).fetchone()
+
+
+def update_source_doc(source_doc_id, *, body_text=None, last_synced=None, metadata_patch=None):
+    with _conn() as conn:
+        before = conn.execute(
+            "SELECT * FROM source_docs WHERE id=%s", (source_doc_id,)
+        ).fetchone()
+        sets, args = [], []
+        if body_text is not None:
+            sets.append("body_text=%s"); args.append(body_text)
+        if last_synced is not None:
+            sets.append("last_synced=%s"); args.append(last_synced)
+        if metadata_patch is not None:
+            sets.append("metadata = coalesce(metadata, '{}'::jsonb) || %s::jsonb")
+            args.append(json.dumps(metadata_patch))
+        if not sets:
+            return before
+        sets.append("updated_at=now()")
+        args.append(source_doc_id)
+        after = conn.execute(
+            f"UPDATE source_docs SET {', '.join(sets)} WHERE id=%s RETURNING *", args
+        ).fetchone()
+        conn.execute("""
+          INSERT INTO audit_log(actor_kind, actor_id, entity_type, entity_id, action, diff)
+          VALUES('worker', NULL, 'source_doc', %s, 'update', %s)
+        """, (source_doc_id,
+              json.dumps({"kind": "update",
+                          "changes": {"body_text": "updated" if body_text is not None else None}})))
+        return after