feat: implement background processing for binary attachments in Obsidian plugin

- Added a new Celery task for indexing non-markdown attachments.
- Enhanced the Obsidian plugin schema to support binary attachments.
- Updated routes to enqueue binary attachments for background processing.
- Improved metadata handling for binary attachments during indexing.
- Added tests for binary attachment processing and validation.

surfsense_backend/tests/unit/test_obsidian_plugin_indexer.py

@@ -1,9 +1,18 @@
 from __future__ import annotations
 
+import base64
 from datetime import UTC, datetime
 
+import pytest
+
+from app.etl_pipeline.etl_document import EtlResult
 from app.schemas.obsidian_plugin import HeadingRef, NotePayload
-from app.services.obsidian_plugin_indexer import _build_metadata
+from app.services.obsidian_plugin_indexer import (
+    _build_metadata,
+    _extract_binary_attachment_markdown,
+    _is_image_attachment,
+    _require_extracted_attachment_content,
+)
 
 
 def test_build_metadata_serializes_headings_to_plain_json() -> None:
@@ -23,3 +32,130 @@ def test_build_metadata_serializes_headings_to_plain_json() -> None:
     metadata = _build_metadata(payload, vault_name="My Vault", connector_id=42)
 
     assert metadata["headings"] == [{"heading": "Notes", "level": 1}]
+
+
+def test_build_metadata_marks_binary_attachment_fields() -> None:
+    now = datetime.now(UTC)
+    payload = NotePayload(
+        vault_id="vault-1",
+        path="assets/diagram.png",
+        name="diagram",
+        extension="png",
+        content="",
+        content_hash="abc123",
+        mtime=now,
+        ctime=now,
+        is_binary=True,
+        mime_type="image/png",
+    )
+
+    metadata = _build_metadata(payload, vault_name="My Vault", connector_id=42)
+
+    assert metadata["is_binary"] is True
+    assert metadata["mime_type"] == "image/png"
+
+
+@pytest.mark.asyncio
+async def test_extract_binary_attachment_markdown_handles_invalid_base64() -> None:
+    now = datetime.now(UTC)
+    payload = NotePayload(
+        vault_id="vault-1",
+        path="assets/diagram.png",
+        name="diagram",
+        extension="png",
+        content="",
+        content_hash="abc123",
+        mtime=now,
+        ctime=now,
+        is_binary=True,
+        binary_base64="not-valid-base64!!",
+    )
+
+    content, metadata = await _extract_binary_attachment_markdown(
+        payload, vision_llm=None
+    )
+
+    assert content == ""
+    assert metadata["attachment_extraction_status"] == "invalid_binary_payload"
+
+
+@pytest.mark.asyncio
+async def test_extract_binary_attachment_markdown_uses_etl(monkeypatch) -> None:
+    now = datetime.now(UTC)
+    payload = NotePayload(
+        vault_id="vault-1",
+        path="assets/spec.pdf",
+        name="spec",
+        extension="pdf",
+        content="",
+        content_hash="abc123",
+        mtime=now,
+        ctime=now,
+        is_binary=True,
+        binary_base64=base64.b64encode(b"%PDF-1.7 fake bytes").decode("ascii"),
+    )
+
+    async def _fake_run_etl_extract(  # noqa: ANN001
+        *, file_path, filename, vision_llm
+    ):
+        assert filename == "spec.pdf"
+        assert file_path
+        assert vision_llm is None
+        return EtlResult(
+            markdown_content="Extracted content",
+            etl_service="TEST_ETL",
+            content_type="document",
+        )
+
+    monkeypatch.setattr(
+        "app.services.obsidian_plugin_indexer._run_etl_extract",
+        _fake_run_etl_extract,
+    )
+
+    content, metadata = await _extract_binary_attachment_markdown(
+        payload, vision_llm=None
+    )
+
+    assert content == "Extracted content"
+    assert metadata["attachment_extraction_status"] == "ok"
+    assert metadata["attachment_etl_service"] == "TEST_ETL"
+
+
+def test_is_image_attachment_detects_image_extensions() -> None:
+    now = datetime.now(UTC)
+    image_payload = NotePayload(
+        vault_id="vault-1",
+        path="assets/screenshot.PNG",
+        name="screenshot",
+        extension="PNG",
+        content="",
+        content_hash="abc123",
+        mtime=now,
+        ctime=now,
+        is_binary=True,
+    )
+    pdf_payload = NotePayload(
+        vault_id="vault-1",
+        path="assets/spec.pdf",
+        name="spec",
+        extension="pdf",
+        content="",
+        content_hash="abc123",
+        mtime=now,
+        ctime=now,
+        is_binary=True,
+    )
+
+    assert _is_image_attachment(image_payload) is True
+    assert _is_image_attachment(pdf_payload) is False
+
+
+def test_require_extracted_attachment_content_rejects_empty_content() -> None:
+    with pytest.raises(
+        RuntimeError, match="Attachment extraction failed for assets/img.png"
+    ):
+        _require_extracted_attachment_content(
+            content="   ",
+            etl_meta={"attachment_extraction_status": "etl_failed"},
+            path="assets/img.png",
+        )