diff --git a/backend/app/routers/letters.py b/backend/app/routers/letters.py
index 4812bbb..80e8e21 100644
--- a/backend/app/routers/letters.py
+++ b/backend/app/routers/letters.py
@@ -1,5 +1,6 @@
 """Letter upload + retrieval endpoints (auth-required, /api/letters/*)."""
 
+import logging
 from uuid import UUID
 
 from fastapi import APIRouter, Depends, File, Query, UploadFile
@@ -27,6 +28,8 @@
 from app.services.persistence import persist_extraction
 from app.services.storage import detect_magic_mime, save_letter_file
 
+logger = logging.getLogger("klar.letters")
+
 router = APIRouter(prefix="/api/letters", tags=["letters"])
 
 ACCEPTED_MIMES = {
@@ -221,6 +224,7 @@ async def extract_letter(
             letter.original_file, mime, lang=letter.language
         )
     except PdfRenderError as exc:
+        logger.info("PDF render failed for letter %s: %s", letter.id, exc)
         letter.status = LetterStatus.ERROR
         db.add(letter)
         db.commit()
@@ -228,17 +232,26 @@ async def extract_letter(
         # actionable message ("try uploading it as an image instead").
         raise KlarHTTPException(502, ErrorCode.PDF_RENDER_FAILED, message=str(exc))
     except ExtractionError as exc:
+        logger.info("Extraction produced no text for letter %s: %s", letter.id, exc)
         letter.status = LetterStatus.ERROR
         db.add(letter)
         db.commit()
         # Scanned image-only PDF (no text layer) or malformed model output —
         # surface the typed, user-friendly message instead of a raw 500.
         raise KlarHTTPException(502, ErrorCode.EXTRACTION_FAILED, message=str(exc))
-    except Exception:
+    except Exception as exc:
+        # Log the real error so we can diagnose in production. The 502
+        # response stays generic to avoid leaking provider details.
+        # NOTE: KlarHTTPException is caught by klar_exception_handler (not
+        # unhandled_exception_handler), so without this logger.exception()
+        # the original traceback would be silently lost.
+        logger.exception(
+            "Qwen extraction failed for letter %s: %s",
+            letter.id, exc,
+        )
         letter.status = LetterStatus.ERROR
         db.add(letter)
         db.commit()
-        # Don't leak the raw exception. Logged by unhandled_exception_handler.
         raise KlarHTTPException(502, ErrorCode.EXTRACTION_FAILED)
 
     actions = persist_extraction(db, letter, extracted)
diff --git a/backend/tests/test_scanned_pdf_graceful.py b/backend/tests/test_scanned_pdf_graceful.py
index 4a07122..cc7d2bb 100644
--- a/backend/tests/test_scanned_pdf_graceful.py
+++ b/backend/tests/test_scanned_pdf_graceful.py
@@ -354,3 +354,85 @@ async def _render_fail(path):
 
     assert "event: error" in blob
     assert ErrorCode.PDF_RENDER_FAILED.value in blob
+
+
+# --------------------------------------------------------------------------
+# 7. /api/letters/{id}/extract — the sync extract endpoint in letters.py must
+#    log errors and return typed 502s, NOT silently swallow tracebacks.
+# --------------------------------------------------------------------------
+
+
+async def _call_extract_letter(monkeypatch, *, raise_exc):
+    """Drive letters.extract_letter with extraction stubbed to raise `raise_exc`.
+
+    Returns the KlarHTTPException the handler raises (or None if it didn't).
+    """
+    from app.routers import letters
+
+    async def _boom(*a, **k):
+        raise raise_exc
+
+    monkeypatch.setattr(letters, "extract_from_letter_file", _boom)
+
+    with Session(engine) as db:
+        from app.models import User
+
+        user = User(email=f"extract-{uuid4()}@example.com", language="en")
+        db.add(user)
+        db.commit()
+        db.refresh(user)
+
+        letter = Letter(
+            user_id=user.id,
+            language="en",
+            status=LetterStatus.UPLOADED,
+            original_file="/tmp/scanned.pdf",
+        )
+        db.add(letter)
+        db.commit()
+        db.refresh(letter)
+
+        try:
+            await letters.extract_letter(letter_id=letter.id, db=db, user=user)
+        except Exception as exc:  # noqa: BLE001 — we assert on the typed error
+            return exc
+    return None
+
+
+async def test_extract_letter_scanned_pdf_returns_extraction_failed(monkeypatch):
+    from app.errors import KlarHTTPException
+
+    exc = await _call_extract_letter(
+        monkeypatch,
+        raise_exc=ExtractionError("scanned image without readable content"),
+    )
+    assert isinstance(exc, KlarHTTPException)
+    assert exc.status_code == 502
+    assert exc.code == ErrorCode.EXTRACTION_FAILED
+    assert "readable content" in exc.message
+
+
+async def test_extract_letter_corrupt_pdf_returns_pdf_render_failed(monkeypatch):
+    from app.errors import KlarHTTPException
+
+    exc = await _call_extract_letter(
+        monkeypatch,
+        raise_exc=PdfRenderError("Could not render this PDF. It may be corrupt."),
+    )
+    assert isinstance(exc, KlarHTTPException)
+    assert exc.status_code == 502
+    assert exc.code == ErrorCode.PDF_RENDER_FAILED
+    assert "corrupt" in exc.message
+
+
+async def test_extract_letter_unexpected_error_stays_generic(monkeypatch):
+    from app.errors import KlarHTTPException
+
+    exc = await _call_extract_letter(
+        monkeypatch, raise_exc=RuntimeError("some provider 500 with secrets")
+    )
+    assert isinstance(exc, KlarHTTPException)
+    assert exc.status_code == 502
+    assert exc.code == ErrorCode.EXTRACTION_FAILED
+    # Raw provider error must NOT leak into the user-facing message.
+    assert "secrets" not in exc.message