Chris CoutinhoandClaude Opus 4.8
bc957b5bc7
Address PR #858 review round 3: - document_tier1_engine / document_ocr_provider now validate + normalize via Settings.__post_init__ _enum_fields (the repo's canonical opt-in-enum pattern; case-insensitive) instead of dynaconf Validators. A typo now raises ValueError at load and "Gateway" normalizes to "gateway". - classify_from_text gates no_text_layer/bad_text_layer on ocr_frac >= OCR_PAGE_FRACTION, matching classify_pdf -- a "fast"-routed doc with a few junk pages no longer emits a misleading flag (keeps the shadow vs hot-path classification metrics consistent). - build_ocr_backend warns when an EXPLICIT provider is misconfigured (gateway without EMBEDDING_GATEWAY_URL, mistral without MISTRAL_API_KEY) instead of silently returning None. - Pypdfium2FastProcessor.health_check probes the import; documented why OcrProcessor.health_check is unconditionally True (lazy per-tenant backends). - Removed the leftover per-boundary / per-chunk debug logging loops. Tests: enum normalization + rejection for the two new settings. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
278 lines
10 KiB
Python
278 lines
10 KiB
Python
"""Tier-3 OCR processor.
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Routes scanned / no-text-layer PDFs (the tier-0 classifier's ``ocr`` verdict) to
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an OCR backend that returns per-page markdown. Two interchangeable backends,
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selected by ``document_ocr_provider``:
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* ``gateway`` -- POST the document to the Astrolabe Cloud model gateway's
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``POST /v1/ocr`` (the same M2M-authenticated gateway as embeddings; NO
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provider keys in the pod). The platform default.
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* ``mistral`` -- call the Mistral OCR API directly from the pod
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(``MISTRAL_API_KEY``), for self-hosters / deployments without the gateway.
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``auto`` prefers the gateway (if ``EMBEDDING_GATEWAY_URL`` is set) then direct
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Mistral (if ``MISTRAL_API_KEY``). Both return GitHub-flavoured markdown + exact
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``page_boundaries``; bbox is re-derived from the PDF bytes + boundaries by
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``search/pdf_highlighter``, as for the other tiers.
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"""
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import base64
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import logging
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from abc import ABC, abstractmethod
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from collections.abc import Awaitable, Callable
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from typing import Any
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import anyio
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import httpx
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from nextcloud_mcp_server.config import Settings, get_settings
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from .base import DocumentProcessor, ProcessingResult
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logger = logging.getLogger(__name__)
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_OCR_TIMEOUT_SECONDS = 180.0
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def _pages_to_text(
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pages: list[tuple[int, str]],
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) -> tuple[str, list[dict[str, Any]]]:
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"""Join per-page markdown (ordered by index) into one string + boundaries.
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Pages are joined with a blank line. Boundaries are kept CONTIGUOUS (each
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page owns its leading ``\\n\\n`` separator) so they index exactly into the
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returned text and ``boundaries[-1]["end_offset"] == len(text)`` -- the
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``search/pdf_highlighter`` contract. Consequence: a page's range starts at
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its separator, not its first glyph (the fast pypdfium2 path joins with no
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separator, so its ranges are glyph-tight). The 2-char offset is immaterial
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to page-level chunk attribution.
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"""
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sep = "\n\n"
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parts: list[str] = []
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boundaries: list[dict[str, Any]] = []
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offset = 0
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for i, (index, markdown) in enumerate(sorted(pages, key=lambda p: p[0])):
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chunk = markdown if i == 0 else sep + markdown
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start = offset
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offset += len(chunk)
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parts.append(chunk)
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boundaries.append(
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{"page": index + 1, "start_offset": start, "end_offset": offset}
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)
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return "".join(parts), boundaries
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class _OcrBackend(ABC):
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@abstractmethod
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async def ocr(
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self, content: bytes, mime_type: str
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) -> tuple[str, list[dict[str, Any]]]: ...
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class _GatewayOcrBackend(_OcrBackend):
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"""Calls the model gateway's ``POST /v1/ocr`` (key-isolated, M2M-authed)."""
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def __init__(self, base_url: str, model: str, token_provider: Any = None):
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base = base_url.rstrip("/")
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if not base.endswith("/v1"):
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base = f"{base}/v1"
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self._url = f"{base}/ocr"
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self._model = model
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self._token_provider = token_provider
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async def ocr(
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self, content: bytes, mime_type: str
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) -> tuple[str, list[dict[str, Any]]]:
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headers: dict[str, str] = {}
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if self._token_provider is not None:
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headers["Authorization"] = (
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f"Bearer {await self._token_provider.get_token()}"
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)
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payload = {
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"model": self._model,
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"document_b64": base64.b64encode(content).decode("ascii"),
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"mime_type": mime_type,
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}
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async with httpx.AsyncClient(
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timeout=httpx.Timeout(_OCR_TIMEOUT_SECONDS, connect=10.0)
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) as client:
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resp = await client.post(self._url, json=payload, headers=headers)
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resp.raise_for_status()
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body = resp.json()
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pages = [(p["index"], p.get("markdown", "")) for p in body.get("pages", [])]
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return _pages_to_text(pages)
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class _MistralOcrBackend(_OcrBackend):
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"""Calls the Mistral OCR API directly (provider key lives in the pod)."""
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def __init__(self, api_key: str, model: str, base_url: str | None = None):
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from mistralai.client import Mistral # noqa: PLC0415 -- lazy SDK import
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self._client = Mistral(api_key=api_key, server_url=base_url)
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# The gateway-namespaced "mistral/<model>" id strips down to the bare
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# upstream model the SDK expects.
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self._model = model.split("/", 1)[-1]
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async def ocr(
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self, content: bytes, mime_type: str
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) -> tuple[str, list[dict[str, Any]]]:
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data_url = (
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f"data:{mime_type};base64,{base64.b64encode(content).decode('ascii')}"
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)
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resp = await self._client.ocr.process_async(
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model=self._model,
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document={"type": "document_url", "document_url": data_url},
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)
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pages = [(p.index, p.markdown or "") for p in (resp.pages or [])]
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return _pages_to_text(pages)
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def build_ocr_backend(settings: Settings) -> _OcrBackend | None:
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"""Select an OCR backend from settings, or None when none is available."""
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provider = settings.document_ocr_provider
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if provider == "none":
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return None
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if provider in ("gateway", "auto") and settings.embedding_gateway_url:
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token_provider = None
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if settings.embedding_gateway_client_id:
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# Lazy import avoids a document_processors -> embedding cycle at load.
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from ..embedding.gateway_client import ( # noqa: PLC0415
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GatewayTokenProvider,
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)
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# Explicit (not assert -- assert is stripped under `python -O`): the
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# M2M triple is all-or-nothing.
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if not settings.embedding_gateway_token_url:
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raise ValueError(
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"EMBEDDING_GATEWAY_TOKEN_URL is required when "
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"EMBEDDING_GATEWAY_CLIENT_ID is set"
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)
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if not settings.embedding_gateway_client_secret:
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raise ValueError(
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"EMBEDDING_GATEWAY_CLIENT_SECRET is required when "
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"EMBEDDING_GATEWAY_CLIENT_ID is set"
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)
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token_provider = GatewayTokenProvider(
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token_url=settings.embedding_gateway_token_url,
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client_id=settings.embedding_gateway_client_id,
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client_secret=settings.embedding_gateway_client_secret,
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scope=settings.embedding_gateway_scope,
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)
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return _GatewayOcrBackend(
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settings.embedding_gateway_url, settings.document_ocr_model, token_provider
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)
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if provider in ("mistral", "auto") and settings.mistral_api_key:
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return _MistralOcrBackend(
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settings.mistral_api_key,
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settings.document_ocr_model,
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settings.mistral_base_url,
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)
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# An EXPLICIT provider that's missing its config is an operator error -- warn
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# loudly (once, since the backend is resolved+cached) rather than silently
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# disabling OCR. "auto"/"none" fall through to None quietly by design.
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if provider == "gateway":
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logger.warning(
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"DOCUMENT_OCR_PROVIDER=gateway but EMBEDDING_GATEWAY_URL is unset; "
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"OCR is disabled"
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)
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elif provider == "mistral":
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logger.warning(
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"DOCUMENT_OCR_PROVIDER=mistral but MISTRAL_API_KEY is unset; "
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"OCR is disabled"
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)
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return None
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class OcrProcessor(DocumentProcessor):
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"""Tier-3 OCR processor (gateway or direct Mistral backend)."""
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def __init__(self) -> None:
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# Resolve the backend once and reuse it: rebuilding per call would create
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# a fresh GatewayTokenProvider each time (discarding its M2M-token cache
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# -> a token fetch per document) and a new Mistral SDK client per call.
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# A config change needs a pod restart anyway, so caching for the pod's
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# lifetime is safe.
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self._backend_resolved = False
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self._backend: _OcrBackend | None = None
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# Serialise first-call resolution so a burst of concurrent OCR requests
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# doesn't each build a backend (and fetch its own M2M token). Lazy-init:
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# anyio primitives must not be created at import time.
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self._backend_lock: anyio.Lock | None = None
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@property
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def name(self) -> str:
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return "ocr"
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@property
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def tier(self) -> str:
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return "ocr"
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@property
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def supported_mime_types(self) -> set[str]:
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return {"application/pdf"}
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async def process(
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self,
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content: bytes,
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content_type: str,
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filename: str | None = None,
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options: dict[str, Any] | None = None,
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progress_callback: (
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Callable[[float, float | None, str | None], Awaitable[None]] | None
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) = None,
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) -> ProcessingResult:
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settings = get_settings()
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if not self._backend_resolved:
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if self._backend_lock is None:
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self._backend_lock = anyio.Lock()
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async with self._backend_lock:
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if not self._backend_resolved: # double-checked
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self._backend = build_ocr_backend(settings)
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self._backend_resolved = True
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backend = self._backend
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if backend is None:
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logger.warning(
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"OCR requested for %s but no backend is configured (provider=%s)",
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filename or "<bytes>",
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settings.document_ocr_provider,
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)
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return ProcessingResult(
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text="",
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metadata={"parse_failed_reason": "unsupported"},
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processor=self.name,
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success=False,
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error="no OCR backend configured",
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)
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try:
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text, boundaries = await backend.ocr(
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content, content_type.split(";")[0].strip().lower()
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)
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except Exception as e:
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logger.warning("OCR failed for %s: %s", filename or "<bytes>", e)
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return ProcessingResult(
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text="",
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metadata={"parse_failed_reason": "error"},
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processor=self.name,
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success=False,
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error=f"{type(e).__name__}: {e}",
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)
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return ProcessingResult(
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text=text,
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metadata={
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"page_count": len(boundaries),
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"page_boundaries": boundaries,
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"file_size": len(content),
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},
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processor=self.name,
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)
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async def health_check(self) -> bool:
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# Backends are resolved lazily (and configured per tenant), so there is
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# nothing to probe here without making a billable upstream call -- the
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# processor reports healthy and surfaces a real failure per-document.
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return True
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