diff --git a/application/api/user/tasks.py b/application/api/user/tasks.py
index d85e38f8..2229f804 100644
--- a/application/api/user/tasks.py
+++ b/application/api/user/tasks.py
@@ -219,7 +219,9 @@ def _emit_attachment_poison_event(task_name, bound):
 
     Mirrors ``_emit_ingest_poison_event``: the guard returns before the
     worker runs, so ``attachment_worker``'s own events never fire and the
-    upload toast would otherwise spin on "processing" forever.
+    upload toast would otherwise spin on "processing" forever. Also writes
+    the failure row the worker never got to write, so the poisoned upload
+    stays visible to a DB scan and not just to whoever saw the toast.
     """
     user = bound.get("user")
     file_info = bound.get("file_info") or {}
@@ -227,7 +229,11 @@ def _emit_attachment_poison_event(task_name, bound):
     if not user or not attachment_id:
         return
     from application.events.publisher import publish_user_event
+    from application.worker import record_attachment_failure
 
+    record_attachment_failure(
+        user, file_info, "Attachment processing stopped after repeated failures."
+    )
     publish_user_event(
         user,
         "attachment.failed",
diff --git a/application/llm/handlers/base.py b/application/llm/handlers/base.py
index 5983f796..ef379823 100644
--- a/application/llm/handlers/base.py
+++ b/application/llm/handlers/base.py
@@ -316,11 +316,39 @@ class LLMHandler(ABC):
         attachment_texts = []
 
         for attachment in attachments:
-            logger.info(f"Adding attachment {attachment.get('id')} to context")
-            if "content" in attachment:
-                attachment_texts.append(
-                    f"Attached file content:\n\n{attachment['content']}"
+            # ``metadata.extraction`` records what parsing actually did.
+            # Rows predating it have no ``extraction`` key and pass; rows
+            # whose extraction failed must not reach the prompt (a PG row
+            # always has a ``content`` key, so key membership is no gate).
+            extraction = (attachment.get("metadata") or {}).get("extraction") or {}
+            status = extraction.get("status")
+            if status is not None and status != "ok":
+                logger.info(
+                    f"Skipping attachment {attachment.get('id')}: extraction status {status}"
                 )
+                continue
+            content = attachment.get("content")
+            if content is None:
+                logger.info(
+                    f"Skipping attachment {attachment.get('id')}: no extracted content"
+                )
+                continue
+            logger.info(f"Adding attachment {attachment.get('id')} to context")
+            note = ""
+            if extraction.get("truncated"):
+                stored = extraction.get("stored_tokens")
+                original = extraction.get("original_tokens")
+                counts = (
+                    f"only the first {stored:,} of ~{original:,} tokens are included"
+                    if isinstance(stored, int) and isinstance(original, int)
+                    else "part of the document is missing"
+                )
+                name = attachment.get("filename") or "This file"
+                note = (
+                    f'[NOTE: "{name}" was truncated during extraction — {counts}. '
+                    "Scope any whole-document claims to this portion.]\n\n"
+                )
+            attachment_texts.append(f"Attached file content:\n\n{note}{content}")
         if attachment_texts:
             combined_text = "\n\n".join(attachment_texts)
 
diff --git a/application/parser/chunking.py b/application/parser/chunking.py
index 322c356b..32366b4f 100644
--- a/application/parser/chunking.py
+++ b/application/parser/chunking.py
@@ -44,8 +44,8 @@ class Chunker:
     def split_document(self, doc: Document) -> List[Document]:
         split_docs = []
         header, body = self.separate_header_and_body(doc.text)
-        header_tokens = self.encoding.encode(header) if header else []
-        body_tokens = self.encoding.encode(body)
+        header_tokens = self.encoding.encode_ordinary(header) if header else []
+        body_tokens = self.encoding.encode_ordinary(body)
 
         current_position = 0
         part_index = 0
@@ -71,7 +71,7 @@ class Chunker:
         i = 0
         while i < len(documents):
             doc = documents[i]
-            tokens = self.encoding.encode(doc.text)
+            tokens = self.encoding.encode_ordinary(doc.text)
             token_count = len(tokens)
 
             if self.min_tokens <= token_count <= self.max_tokens:
diff --git a/application/parser/chunking_strategies.py b/application/parser/chunking_strategies.py
index 6e4a0dcb..933ec7f0 100644
--- a/application/parser/chunking_strategies.py
+++ b/application/parser/chunking_strategies.py
@@ -44,11 +44,11 @@ class _BaseStrategyChunker:
         self.encoding = get_encoding()
 
     def _token_count(self, text: str) -> int:
-        return len(self.encoding.encode(text))
+        return len(self.encoding.encode_ordinary(text))
 
     def _split_by_tokens(self, text: str) -> List[str]:
         """Split ``text`` into pieces no larger than ``max_tokens`` tokens."""
-        tokens = self.encoding.encode(text)
+        tokens = self.encoding.encode_ordinary(text)
         pieces = []
         for start in range(0, len(tokens), self.max_tokens):
             chunk_tokens = tokens[start:start + self.max_tokens]
@@ -188,7 +188,7 @@ class ParentChildChunker(_BaseStrategyChunker):
         processed: List[Document] = []
         child_size = self._child_size()
         for doc in documents:
-            tokens = self.encoding.encode(doc.text)
+            tokens = self.encoding.encode_ordinary(doc.text)
             part_index = 0
             for p_start in range(0, len(tokens), self.max_tokens):
                 parent_tokens = tokens[p_start:p_start + self.max_tokens]
diff --git a/application/parser/document_reader.py b/application/parser/document_reader.py
index 978e29bd..57bb2a98 100644
--- a/application/parser/document_reader.py
+++ b/application/parser/document_reader.py
@@ -263,8 +263,15 @@ def _docling_structured(path: Path, *, ocr_enabled: bool, include_tables: bool,
     if include_tables:
         for tbl in getattr(doc, "tables", []) or []:
             try:
+                from application.parser.file.tabular_parser import cell_to_text
+
+                # ``astype(str)`` leaks pandas-3 NaNs and mangles gapped int
+                # columns ("1001.0") — same contract as the tabular parser.
                 df = tbl.export_to_dataframe()
-                tables.append({"columns": [str(c) for c in df.columns], "rows": df.astype(str).values.tolist()})
+                tables.append({
+                    "columns": [cell_to_text(c) for c in df.columns],
+                    "rows": [[cell_to_text(v) for v in row] for row in df.values.tolist()],
+                })
             except Exception:
                 try:
                     tables.append({"markdown": tbl.export_to_markdown()})
diff --git a/application/utils.py b/application/utils.py
index 16dad7b8..80f21b07 100644
--- a/application/utils.py
+++ b/application/utils.py
@@ -105,7 +105,10 @@ def truncate_to_line_boundary(data: bytes) -> bytes:
 def num_tokens_from_string(string: str) -> int:
     encoding = get_encoding()
     if isinstance(string, str):
-        num_tokens = len(encoding.encode(string))
+        # encode_ordinary: plain ``encode()`` raises ValueError on literal
+        # special-token text like <|endoftext|>, which user documents
+        # legitimately contain.
+        num_tokens = len(encoding.encode_ordinary(string))
         return num_tokens
     else:
         return 0
diff --git a/application/vectorstore/base.py b/application/vectorstore/base.py
index e58fb4d9..1a999f26 100644
--- a/application/vectorstore/base.py
+++ b/application/vectorstore/base.py
@@ -51,7 +51,7 @@ class RemoteEmbeddings:
         def clip(text):
             if not isinstance(text, str):
                 return text
-            tokens = encoding.encode(text)
+            tokens = encoding.encode_ordinary(text)
             if len(tokens) <= limit:
                 return text
             logging.warning(
diff --git a/application/worker.py b/application/worker.py
index c152c25b..4f00da42 100755
--- a/application/worker.py
+++ b/application/worker.py
@@ -57,6 +57,7 @@ from application.storage.db.source_config import SourceConfig
 from application.storage.storage_creator import StorageCreator
 from application.utils import (
     count_tokens_docs,
+    get_encoding,
     num_tokens_from_string,
     safe_filename,
     truncate_to_line_boundary,
@@ -67,6 +68,9 @@ from application.utils import (
 
 MIN_TOKENS = 150
 MAX_TOKENS = 1250
+# Attachment content stored for prompting is capped in tokens — the same
+# unit the gate is expressed in — so a stored row can never exceed the cap.
+ATTACHMENT_MAX_TOKENS = 100_000
 RECURSION_DEPTH = 2
 INGEST_HEARTBEAT_INTERVAL_SECONDS = 30
 
@@ -1539,6 +1543,93 @@ def _bounded_attachment_copy(local_path: str) -> tuple[str, bool]:
     return tmp.name, True
 
 
+def _upsert_attachment_row(
+    user, filename, relative_path, *, mime_type, content, token_count, metadata, attachment_id
+):
+    """Create or update the attachment row for one upload handle.
+
+    The upload route mints a UUID-shaped ``attachment_id`` (stored in the
+    storage path); the PG ``attachments.id`` is DB-generated, so the handle
+    lives in ``legacy_mongo_id``. Task retries share the handle — an earlier
+    attempt's failure row is updated in place, never duplicated.
+    """
+    with db_session() as conn:
+        repo = AttachmentsRepository(conn)
+        existing = repo.get_by_legacy_id(str(attachment_id), user)
+        if existing:
+            repo.update(
+                existing["id"],
+                user,
+                {
+                    "filename": filename,
+                    "upload_path": relative_path,
+                    "mime_type": mime_type,
+                    "content": content,
+                    "token_count": token_count,
+                    "metadata": metadata,
+                },
+            )
+        else:
+            repo.create(
+                user,
+                filename,
+                relative_path,
+                mime_type=mime_type,
+                content=content,
+                token_count=token_count,
+                metadata=metadata,
+                legacy_mongo_id=str(attachment_id),
+            )
+
+
+def record_attachment_failure(user, file_info, error, parser=None):
+    """Persist a failure row so a broken parse is visible to a DB scan.
+
+    Called on the worker's error path and by the poison guard; never raises —
+    the original exception must keep propagating, and the parser's error text
+    goes into ``metadata.extraction``, never into ``content``.
+    """
+    attachment_id = file_info.get("attachment_id")
+    filename = file_info.get("filename") or ""
+    if not attachment_id:
+        return
+    try:
+        # An exception after the success write (event publishing, state
+        # updates) must not replace durable extracted content with a
+        # NULL-content failed row.
+        with db_readonly() as conn:
+            existing = AttachmentsRepository(conn).get_by_legacy_id(
+                str(attachment_id), user
+            )
+        if existing is not None and existing.get("content") is not None:
+            return
+        metadata = {
+            **(file_info.get("metadata") or {}),
+            "extraction": {
+                "status": "failed",
+                "parser": parser,
+                "truncated": False,
+                "error": str(error)[:1024],
+            },
+        }
+        _upsert_attachment_row(
+            user,
+            filename,
+            file_info.get("path") or "",
+            mime_type=mimetypes.guess_type(filename)[0] or "application/octet-stream",
+            content=None,
+            token_count=None,
+            metadata=metadata,
+            attachment_id=attachment_id,
+        )
+    except Exception:
+        logging.error(
+            f"Failed to record failure row for attachment {attachment_id}",
+            extra={"user": user},
+            exc_info=True,
+        )
+
+
 def attachment_worker(self, file_info, user):
     """
     Process and store a single attachment without vectorization.
@@ -1548,6 +1639,7 @@ def attachment_worker(self, file_info, user):
     attachment_id = file_info["attachment_id"]
     relative_path = file_info["path"]
     metadata = file_info.get("metadata", {})
+    parser_name = None
 
     publish_user_event(
         user,
@@ -1578,6 +1670,9 @@ def attachment_worker(self, file_info, user):
         file_extractor = get_default_file_extractor(
             ocr_enabled=settings.DOCLING_OCR_ATTACHMENTS_ENABLED
         )
+        _parser = file_extractor.get(os.path.splitext(filename)[1].lower())
+        parser_name = type(_parser).__name__ if _parser is not None else "SimpleDirectoryReader"
+
         def _parse_local_file(local_path: str, **kwargs) -> Document:
             _reject_attachment_zip_bomb(local_path)
             parse_path, is_temp_copy = _bounded_attachment_copy(local_path)
@@ -1606,10 +1701,29 @@ def attachment_worker(self, file_info, user):
         if parser_metadata:
             metadata = {**metadata, **parser_metadata}
 
-        token_count = num_tokens_from_string(content)
-        if token_count > 100000:
-            content = content[:250000]
-            token_count = num_tokens_from_string(content)
+        # Gate and cut in the same unit. The old form gated on tokens but cut
+        # at 250k *chars*, which for dense scripts (CJK ~1.4 tokens/char)
+        # stored 300k+ tokens while looking like a clean extraction.
+        encoding = get_encoding()
+        tokens = encoding.encode_ordinary(content)
+        original_tokens = len(tokens)
+        truncated = original_tokens > ATTACHMENT_MAX_TOKENS
+        if truncated:
+            content = encoding.decode(tokens[:ATTACHMENT_MAX_TOKENS])
+            token_count = ATTACHMENT_MAX_TOKENS
+        else:
+            token_count = original_tokens
+
+        metadata = {
+            **metadata,
+            "extraction": {
+                "status": "ok",
+                "parser": parser_name,
+                "truncated": truncated,
+                "original_tokens": original_tokens,
+                "stored_tokens": token_count,
+            },
+        }
 
         self.update_state(
             state="PROGRESS", meta={"current": 80, "status": "Storing in database"}
@@ -1628,20 +1742,16 @@ def attachment_worker(self, file_info, user):
 
         mime_type = mimetypes.guess_type(filename)[0] or "application/octet-stream"
 
-        # The upload route produces a UUID-shaped ``attachment_id`` (stored
-        # in the storage path) but the PG ``attachments.id`` is generated
-        # by the DB. Keep ``attachment_id`` as the caller-visible handle
-        # used for the storage path, and stash it in ``legacy_mongo_id``
-        # so the attachment row is resolvable via that handle too.
-        with db_session() as conn:
-            AttachmentsRepository(conn).create(
-                user, filename, relative_path,
-                mime_type=mime_type,
-                content=content,
-                token_count=token_count,
-                metadata=metadata,
-                legacy_mongo_id=str(attachment_id),
-            )
+        _upsert_attachment_row(
+            user,
+            filename,
+            relative_path,
+            mime_type=mime_type,
+            content=content,
+            token_count=token_count,
+            metadata=metadata,
+            attachment_id=attachment_id,
+        )
 
         logging.info(
             f"Stored attachment with ID: {attachment_id}", extra={"user": user}
@@ -1675,6 +1785,7 @@ def attachment_worker(self, file_info, user):
             extra={"user": user},
             exc_info=True,
         )
+        record_attachment_failure(user, file_info, e, parser=parser_name)
         publish_user_event(
             user,
             "attachment.failed",
diff --git a/tests/llm/handlers/test_llm_handlers.py b/tests/llm/handlers/test_llm_handlers.py
index a480b27e..1b068eba 100644
--- a/tests/llm/handlers/test_llm_handlers.py
+++ b/tests/llm/handlers/test_llm_handlers.py
@@ -2105,3 +2105,90 @@ class TestHandleToolCallsCompressionSuccess:
             if isinstance(e, dict) and e.get("data", {}).get("status") == "skipped"
         ]
         assert len(skip_events) == 1  # Only second call skipped
+
+
+# ---------------------------------------------------------------------------
+# _append_unsupported_attachments — extraction-provenance gate
+# ---------------------------------------------------------------------------
+
+
+class TestAttachmentExtractionGate:
+    """Rows now carry ``metadata.extraction`` provenance; the append gate
+    must honor it. Legacy rows (no ``extraction`` key) keep working."""
+
+    def test_failed_extraction_row_is_skipped(self):
+        handler = ConcreteHandler()
+        messages = [{"role": "system", "content": "sys"}]
+        attachments = [{
+            "id": "a1",
+            "mime_type": "application/vnd.ms-excel",
+            "content": None,
+            "metadata": {"extraction": {"status": "failed", "error": "docling boom"}},
+        }]
+
+        result = handler._append_unsupported_attachments(messages, attachments)
+
+        assert result[0]["content"] == "sys"
+        assert "None" not in result[0]["content"]
+        assert "docling boom" not in result[0]["content"]
+
+    def test_null_content_row_is_skipped_even_without_extraction(self):
+        # A PG row always has the ``content`` key; key membership is not a
+        # signal. ``content=None`` must never append the string "None".
+        handler = ConcreteHandler()
+        messages = [{"role": "system", "content": "sys"}]
+        attachments = [{"id": "a1", "mime_type": "text/plain", "content": None}]
+
+        result = handler._append_unsupported_attachments(messages, attachments)
+
+        assert result[0]["content"] == "sys"
+
+    def test_legacy_row_without_extraction_still_appended(self):
+        handler = ConcreteHandler()
+        messages = [{"role": "system", "content": "sys"}]
+        attachments = [{
+            "id": "a1",
+            "content": "legacy file text",
+            "metadata": {"storage_type": "local"},
+        }]
+
+        result = handler._append_unsupported_attachments(messages, attachments)
+
+        assert "legacy file text" in result[0]["content"]
+
+    def test_ok_row_appended_without_truncation_notice(self):
+        handler = ConcreteHandler()
+        messages = [{"role": "system", "content": "sys"}]
+        attachments = [{
+            "id": "a1",
+            "content": "full file text",
+            "metadata": {"extraction": {"status": "ok", "truncated": False}},
+        }]
+
+        result = handler._append_unsupported_attachments(messages, attachments)
+
+        assert "full file text" in result[0]["content"]
+        assert "truncated" not in result[0]["content"]
+
+    def test_truncated_row_appended_with_partial_document_notice(self):
+        handler = ConcreteHandler()
+        messages = [{"role": "system", "content": "sys"}]
+        attachments = [{
+            "id": "a1",
+            "filename": "big.pdf",
+            "content": "partial file text",
+            "metadata": {"extraction": {
+                "status": "ok",
+                "truncated": True,
+                "original_tokens": 250000,
+                "stored_tokens": 100000,
+            }},
+        }]
+
+        result = handler._append_unsupported_attachments(messages, attachments)
+
+        prompt = result[0]["content"]
+        assert "partial file text" in prompt
+        assert "truncated" in prompt
+        assert "100,000" in prompt
+        assert "250,000" in prompt
diff --git a/tests/parser/file/test_markdown_parser.py b/tests/parser/file/test_markdown_parser.py
index c3cb61ea..bed76ce1 100644
--- a/tests/parser/file/test_markdown_parser.py
+++ b/tests/parser/file/test_markdown_parser.py
@@ -11,6 +11,9 @@ class _Enc:
     def encode(self, s: str):
         return list(s)
 
+    def encode_ordinary(self, s: str):
+        return list(s)
+
 
 @pytest.fixture(autouse=True)
 def _patch_tokenizer(monkeypatch):
diff --git a/tests/parser/test_chunking.py b/tests/parser/test_chunking.py
index 97126f58..55e2e587 100644
--- a/tests/parser/test_chunking.py
+++ b/tests/parser/test_chunking.py
@@ -281,3 +281,24 @@ class TestChunkerIntegration:
             assert doc.extra_info is not None
             assert "token_count" in doc.extra_info
             assert doc.extra_info["token_count"] > 0
+
+
+# =====================================================================
+# Special-token text must chunk as ordinary text, not raise
+# =====================================================================
+
+
+@pytest.mark.unit
+class TestSpecialTokenText:
+
+    def test_chunking_document_containing_special_token_markers(self):
+        # A document ABOUT LLMs contains literal <|endoftext|>; plain
+        # ``encode()`` raises ValueError on it and destroyed the ingest.
+        chunker = Chunker(chunking_strategy="classic_chunk", max_tokens=50, min_tokens=0)
+        doc = Document(
+            text="The <|endoftext|> marker separates documents. " * 30,
+            doc_id="d1",
+        )
+        chunks = chunker.chunk([doc])
+        assert chunks
+        assert all("<|endoftext|>" in c.text for c in chunks[:1])
diff --git a/tests/parser/test_document_reader.py b/tests/parser/test_document_reader.py
index 83d2e435..e73ef3a3 100644
--- a/tests/parser/test_document_reader.py
+++ b/tests/parser/test_document_reader.py
@@ -564,3 +564,61 @@ def test_vanilla_converter_applies_inference_settings(monkeypatch, tmp_path):
 
     assert out["markdown"] == "# md"
     assert called == [True]
+
+
+# ---------------------------------------------------------------------------
+# _docling_structured tables: blank cells must not leak NaN or mangle ints
+# ---------------------------------------------------------------------------
+@pytest.mark.unit
+def test_structured_tables_render_blank_cells_as_strings(monkeypatch, tmp_path):
+    """pandas 3 preserves missing values through ``astype(str)``, so a blank
+    spreadsheet cell leaked a float NaN into the tables payload and a blank
+    in an integer column mangled every id to ``1001.0``. Cells must come out
+    as join-safe strings (same contract as the tabular parser's
+    ``cell_to_text``)."""
+    import sys
+    import types
+
+    import pandas as pd
+
+    df = pd.DataFrame({"id": [1001, None, 1003], "name": ["a", "b", None]})
+
+    class _Table:
+        def export_to_dataframe(self):
+            return df
+
+    class _Doc:
+        tables = [_Table()]
+        pages = {"1": {}}
+
+        def export_to_markdown(self):
+            return "# md"
+
+        def export_to_dict(self):
+            return {"texts": [], "tables": [{}], "pages": {"1": {}}}
+
+    class _Converter:
+        def convert(self, *a, **k):
+            return types.SimpleNamespace(document=_Doc())
+
+    monkeypatch.setattr(
+        "application.parser.file.docling_parser._apply_inference_settings",
+        lambda: None,
+    )
+    fake_docling = types.ModuleType("docling")
+    fake_dc_module = types.ModuleType("docling.document_converter")
+    fake_dc_module.DocumentConverter = _Converter
+    fake_docling.document_converter = fake_dc_module
+    monkeypatch.setitem(sys.modules, "docling", fake_docling)
+    monkeypatch.setitem(sys.modules, "docling.document_converter", fake_dc_module)
+
+    path = tmp_path / "doc.xlsx"
+    path.write_bytes(b"stub")
+
+    out = dr._docling_structured(path, ocr_enabled=False, include_tables=True, parser=None)
+
+    [table] = out["tables"]
+    cells = [c for row in table["rows"] for c in row]
+    assert all(isinstance(c, str) for c in cells), f"non-string cells: {cells!r}"
+    assert "1001" in cells and "1001.0" not in cells
+    assert "" in cells  # blank cell renders as empty string, not "nan"/"None"
diff --git a/tests/test_utils.py b/tests/test_utils.py
index 16ec3852..c789ab00 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -102,6 +102,31 @@ class TestNumTokens:
     def test_empty_string(self):
         assert num_tokens_from_string("") == 0
 
+    @pytest.mark.unit
+    def test_special_token_text_counts_instead_of_raising(self):
+        # User documents legitimately contain literal marker text like
+        # <|endoftext|> (any paper about LLMs). Plain ``encode()`` raises
+        # ValueError on it; counting must treat it as ordinary text.
+        count = num_tokens_from_string(
+            "This paper discusses the <|endoftext|> token in GPT models."
+        )
+        assert count > 0
+
+    @pytest.mark.unit
+    def test_unbroken_cjk_run_counts_in_bounded_time(self):
+        # An unbroken letter run is a single BPE piece; tiktoken < 0.13.0
+        # merged it quadratically (~26s for this input, minutes for real
+        # uploads). tiktoken 0.13.0 does it in milliseconds. Guards
+        # against a dependency downgrade re-introducing the hang.
+        import time
+
+        dense = "統計資料表格內容分析報告書類文書處理系統設計開發" * 4000  # 96k chars, one piece
+        start = time.monotonic()
+        count = num_tokens_from_string(dense)
+        elapsed = time.monotonic() - start
+        assert count > 100000
+        assert elapsed < 10, f"pathological encode took {elapsed:.1f}s — tiktoken downgraded?"
+
 
 class TestNumTokensFromObjectOrList:
 
diff --git a/tests/worker/test_attachment_worker.py b/tests/worker/test_attachment_worker.py
index 1f1e8624..4172a944 100644
--- a/tests/worker/test_attachment_worker.py
+++ b/tests/worker/test_attachment_worker.py
@@ -67,7 +67,7 @@ class TestAttachmentWorker:
         assert row["content"] == "hello world"
         assert row["user_id"] == "user1"
 
-    def test_parse_failure_stores_nothing_and_tells_the_user(
+    def test_parse_failure_stores_failure_row_and_tells_the_user(
         self, pg_conn, patch_worker_db, task_self, monkeypatch
     ):
         """A parse failure must fail loudly, not store the error as content.
@@ -76,6 +76,9 @@ class TestAttachmentWorker:
         parser returned its own traceback as the "document", and the worker
         stored it and published ``attachment.completed`` — so the upload
         looked fine and the model was handed an error message as the PDF.
+        The failure now leaves a queryable row whose ``metadata.extraction``
+        records the error; ``content`` stays NULL so the model can never
+        read a traceback as the document.
         """
         from application import worker
         from application.parser.file.base_parser import DocumentParseError
@@ -109,12 +112,17 @@ class TestAttachmentWorker:
         with pytest.raises(DocumentParseError):
             worker.attachment_worker(task_self, file_info, "user1")
 
-        # Nothing may be persisted — an attachment whose text is a traceback
-        # is worse than no attachment, because the model will read it.
+        # The error lives in metadata, never in content — an attachment whose
+        # text is a traceback is worse than no attachment, because the model
+        # will read it.
         row = AttachmentsRepository(pg_conn).get_by_legacy_id(
             file_info["attachment_id"], "user1"
         )
-        assert row is None, "a failed parse must not insert an attachment row"
+        assert row is not None, "a failed parse must leave a queryable row"
+        assert row["content"] is None
+        extraction = row["metadata"]["extraction"]
+        assert extraction["status"] == "failed"
+        assert "InvalidCxxCompiler" in extraction["error"]
 
         # The user is told it failed, and never told it completed.
         events = [event for event, _ in published]
diff --git a/tests/worker/test_attachment_worker_provenance.py b/tests/worker/test_attachment_worker_provenance.py
new file mode 100644
index 00000000..95b49ec8
--- /dev/null
+++ b/tests/worker/test_attachment_worker_provenance.py
@@ -0,0 +1,266 @@
+"""Extraction-provenance tests for ``attachment_worker``.
+
+Every parse attempt must leave a queryable trace in ``attachments``:
+``metadata.extraction`` records what happened (status, parser, truncation,
+token counts, error) on success, truncation, and terminal failure alike.
+Runs against a real ephemeral Postgres so the rows the worker writes are
+asserted as stored, not as mocked calls.
+"""
+
+from __future__ import annotations
+
+import uuid
+from unittest.mock import patch
+
+import pytest
+
+import application.storage.db.engine as engine_module
+from application.parser.file.base_parser import DocumentParseError
+from application.storage.db.repositories.attachments import AttachmentsRepository
+from application.storage.db.session import db_readonly
+from application.utils import get_encoding
+
+
+class _StubTask:
+    def update_state(self, *args, **kwargs):
+        pass
+
+
+class _Doc:
+    def __init__(self, text):
+        self.text = text
+        self.extra_info = {}
+
+
+@pytest.fixture()
+def wired_engine(pg_engine, monkeypatch):
+    """Point the app's module-level engine cache at the ephemeral DB."""
+    monkeypatch.setattr(engine_module, "_engine", None)
+    eng = engine_module.get_engine()
+    yield eng
+    eng.dispose()
+    monkeypatch.setattr(engine_module, "_engine", None)
+
+
+@pytest.fixture()
+def storage_dir(tmp_path, monkeypatch):
+    """LocalStorage rooted at tmp_path, patched into the worker."""
+    from application.storage.local import LocalStorage
+
+    storage = LocalStorage(base_dir=str(tmp_path))
+    monkeypatch.setattr(
+        "application.storage.storage_creator.StorageCreator.get_storage",
+        classmethod(lambda cls: storage),
+    )
+    return tmp_path
+
+
+def _run_worker(file_info, user="prov-user"):
+    from application.worker import attachment_worker
+
+    return attachment_worker(_StubTask(), file_info, user)
+
+
+def _file_info(storage_dir, filename="doc.txt", content=b"hello attachment"):
+    attachment_id = str(uuid.uuid4())
+    rel_path = f"inputs/prov-user/attachments/{attachment_id}/{filename}"
+    full = storage_dir / rel_path
+    full.parent.mkdir(parents=True, exist_ok=True)
+    full.write_bytes(content)
+    return {
+        "filename": filename,
+        "attachment_id": attachment_id,
+        "path": rel_path,
+        "metadata": {"storage_type": "local"},
+    }
+
+
+def _fetch(attachment_id, user="prov-user"):
+    with db_readonly() as conn:
+        return AttachmentsRepository(conn).get_by_legacy_id(str(attachment_id), user)
+
+
+def _count(user="prov-user"):
+    with db_readonly() as conn:
+        return len(AttachmentsRepository(conn).list_for_user(user))
+
+
+@pytest.mark.usefixtures("wired_engine")
+class TestSuccessProvenance:
+    def test_ok_row_records_extraction_metadata(self, storage_dir):
+        info = _file_info(storage_dir)
+
+        result = _run_worker(info)
+
+        row = _fetch(info["attachment_id"])
+        assert row is not None
+        extraction = (row["metadata"] or {}).get("extraction")
+        assert extraction is not None
+        assert extraction["status"] == "ok"
+        assert extraction["truncated"] is False
+        assert extraction["original_tokens"] == extraction["stored_tokens"]
+        assert extraction["stored_tokens"] == row["token_count"]
+        assert extraction.get("parser")
+        assert "hello attachment" in row["content"]
+        assert result["token_count"] == row["token_count"]
+
+    def test_upload_metadata_keys_preserved(self, storage_dir):
+        info = _file_info(storage_dir)
+
+        _run_worker(info)
+
+        row = _fetch(info["attachment_id"])
+        # The storage-level metadata written at upload time must survive
+        # the extraction merge.
+        assert row["metadata"]["storage_type"] == "local"
+
+
+@pytest.mark.usefixtures("wired_engine")
+class TestTruncationProvenance:
+    def test_over_gate_content_truncated_in_token_units(self, storage_dir, monkeypatch):
+        # Dense CJK: ~1.4 tokens/char, so a char-unit cut (the old
+        # behavior) would store far more than 100k tokens.
+        dense = "統計資料表格內容分析、報告書類文書處理系統。設計開發運用管理。\n" * 10000
+        info = _file_info(storage_dir)
+        monkeypatch.setattr(
+            "application.worker.SimpleDirectoryReader",
+            lambda **kwargs: type("R", (), {"load_data": lambda self: [_Doc(dense)]})(),
+        )
+
+        _run_worker(info)
+
+        row = _fetch(info["attachment_id"])
+        extraction = row["metadata"]["extraction"]
+        assert extraction["status"] == "ok"
+        assert extraction["truncated"] is True
+        assert extraction["stored_tokens"] == 100000
+        assert extraction["original_tokens"] > 100000
+        assert row["token_count"] == 100000
+        # The stored content really is ~100k tokens, not a 250k-char cut
+        # still worth 300k+ tokens.
+        enc = get_encoding()
+        assert len(enc.encode_ordinary(row["content"])) <= 100100
+
+    def test_under_gate_content_not_truncated(self, storage_dir, monkeypatch):
+        text = "plain short attachment content"
+        info = _file_info(storage_dir)
+        monkeypatch.setattr(
+            "application.worker.SimpleDirectoryReader",
+            lambda **kwargs: type("R", (), {"load_data": lambda self: [_Doc(text)]})(),
+        )
+
+        _run_worker(info)
+
+        row = _fetch(info["attachment_id"])
+        extraction = row["metadata"]["extraction"]
+        assert extraction["truncated"] is False
+        assert row["content"] == text
+
+
+@pytest.mark.usefixtures("wired_engine")
+class TestFailureProvenance:
+    def test_terminal_parse_failure_writes_failed_row(self, storage_dir, monkeypatch):
+        info = _file_info(storage_dir, filename="broken.xlsx")
+
+        def _raise(**kwargs):
+            raise DocumentParseError("Failed to parse broken.xlsx with docling: boom")
+
+        monkeypatch.setattr("application.worker.SimpleDirectoryReader", _raise)
+
+        with pytest.raises(DocumentParseError):
+            _run_worker(info)
+
+        row = _fetch(info["attachment_id"])
+        assert row is not None, "terminal failure must leave a queryable row"
+        assert row["content"] is None
+        extraction = row["metadata"]["extraction"]
+        assert extraction["status"] == "failed"
+        assert "boom" in extraction["error"]
+        # The parser's exception text must never masquerade as document
+        # content.
+        assert row["token_count"] is None
+
+    def test_retry_then_success_upserts_single_row(self, storage_dir, monkeypatch):
+        info = _file_info(storage_dir)
+        calls = {"n": 0}
+
+        def _flaky(**kwargs):
+            calls["n"] += 1
+            if calls["n"] == 1:
+                raise RuntimeError("transient blip")
+            return type("R", (), {"load_data": lambda self: [_Doc("recovered fine")]})()
+
+        monkeypatch.setattr("application.worker.SimpleDirectoryReader", _flaky)
+
+        with pytest.raises(RuntimeError):
+            _run_worker(info)
+        failed_row = _fetch(info["attachment_id"])
+        assert failed_row["metadata"]["extraction"]["status"] == "failed"
+
+        _run_worker(info)
+
+        assert _count() == 1, "retry success must update the failure row, not add one"
+        row = _fetch(info["attachment_id"])
+        assert row["metadata"]["extraction"]["status"] == "ok"
+        assert row["content"] == "recovered fine"
+
+    def test_post_store_failure_does_not_clobber_ok_row(self, storage_dir):
+        # An exception after the success write (e.g. event publishing) must
+        # not replace stored content with a NULL-content failed row; the
+        # extraction result is already durable.
+        from application.worker import record_attachment_failure
+
+        info = _file_info(storage_dir)
+        _run_worker(info)
+
+        record_attachment_failure("prov-user", info, RuntimeError("post-store blip"))
+
+        row = _fetch(info["attachment_id"])
+        assert row["metadata"]["extraction"]["status"] == "ok"
+        assert "hello attachment" in row["content"]
+
+    def test_failure_row_write_failure_does_not_mask_original_error(
+        self, storage_dir, monkeypatch
+    ):
+        info = _file_info(storage_dir)
+
+        def _raise(**kwargs):
+            raise DocumentParseError("original parse error")
+
+        monkeypatch.setattr("application.worker.SimpleDirectoryReader", _raise)
+        monkeypatch.setattr(
+            "application.worker.db_session",
+            _raising_db_session,
+        )
+
+        with pytest.raises(DocumentParseError, match="original parse error"):
+            _run_worker(info)
+
+
+def _raising_db_session():
+    raise ConnectionError("db down")
+
+
+@pytest.mark.usefixtures("wired_engine")
+class TestPoisonProvenance:
+    def test_poison_guard_writes_failed_row(self):
+        from application.api.user.tasks import _emit_attachment_poison_event
+
+        attachment_id = str(uuid.uuid4())
+        bound = {
+            "user": "prov-user",
+            "file_info": {
+                "filename": "poison.pdf",
+                "attachment_id": attachment_id,
+                "path": "inputs/prov-user/attachments/x/poison.pdf",
+            },
+        }
+
+        with patch("application.events.publisher.publish_user_event"):
+            _emit_attachment_poison_event("store_attachment", bound)
+
+        row = _fetch(attachment_id)
+        assert row is not None, "poison-guard trip must leave a queryable row"
+        extraction = row["metadata"]["extraction"]
+        assert extraction["status"] == "failed"
+        assert "repeated failures" in extraction["error"]