docling separation

docs/content/Deploying/Development-Environment.mdx

@@ -96,6 +96,13 @@ To run the DocsGPT backend locally, you'll need to set up a Python environment a
     pip install -r application/requirements.txt
     ```
 
+    Optionally add the docling parser engine (OCR, `structured` output for
+    `read_document`; the default anydoc engine does not need it):
+
+    ```bash
+    pip install -r application/requirements-docling.txt
+    ```
+
 5.  **Run the Backend:**
 
     For local development, run the ASGI composition under uvicorn. It serves the **whole** application, hot-reloads on source changes, and matches the production runtime:

docs/content/Deploying/DocsGPT-Settings.mdx

@@ -206,7 +206,7 @@ for the engines and flows.
 
 | Setting | Default | Description |
 | --- | --- | --- |
-| `DOC_PARSER_ENGINE` | `anydoc` | Parser engine: `anydoc` (fast Rust converter, no ML models) or `docling` (layout/table models, OCR, structured output; heavy optional install). Files anydoc cannot read fall back to Docling when installed. |
+| `DOC_PARSER_ENGINE` | `anydoc` | Parser engine: `anydoc` (fast Rust converter, no ML models) or `docling` (layout/table models, OCR, structured output). Files anydoc cannot read fall back to Docling when installed. Docling is an optional extra: `pip install -r application/requirements-docling.txt`, or Docker builds with `--build-arg INSTALL_DOCLING=true`. |
 | `DOCLING_OCR_ENABLED` | `false` | OCR for source ingestion (Docling only). |
 | `DOCLING_OCR_ATTACHMENTS_ENABLED` | `false` | OCR for chat attachments (Docling only). |
 | `ATTACHMENT_PDF_TEXT_FAST_PATH` | `true` | Under the `docling` engine, read PDF attachments through their text layer (pypdfium2) and only hand scans to Docling. Not needed under `anydoc`. |

docs/content/Guides/ocr.mdx

@@ -41,6 +41,29 @@ sources, and the fallback for files anydoc rejects. Without Docling those
 formats use the standard parsers, and images are only read when
 `PARSE_IMAGE_REMOTE=true`.
 
+## Installing the docling engine
+
+docling is not part of the base install. Add it when you need OCR,
+`.adoc`/`.vtt`/`.xml` source parsing, or `read_document`'s `structured`
+output:
+
+```bash
+pip install -r application/requirements-docling.txt
+```
+
+Docker images build without it by default; opt in with the build argument:
+
+```bash
+docker build --build-arg INSTALL_DOCLING=true ./application
+```
+
+`deployment/docker-compose.yaml` forwards the same switch, so setting
+`INSTALL_DOCLING=true` in `.env` (or the shell) bakes docling into locally
+built backend and worker images. `setup.sh` writes it automatically when you
+answer yes to the OCR question. Either way no code changes are needed —
+docling is picked up as the fallback engine as soon as it is importable, and
+`DOC_PARSER_ENGINE=docling` makes it the primary one.
+
 ## Docling OCR
 
 OCR is optional, Docling-only, and controlled by two settings: