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feat(vector): replace inline page-image payloads with chunk_bbox (Deck #76)

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Per-chunk PDF page renders (~150–700 KB base64 PNG each) were the dominant
disk consumer in production, repeatedly tripping `No space left on device:
WAL buffer size exceeds available disk space` on welcomed-malamute Qdrant.

Replace the inline highlighted_page_image / highlighted_page_number /
highlight_count fields with a small `chunk_bbox` field:
list[(x0, y0, x1, y1)] of normalized [0, 1] floats, ~32 bytes per chunk.
Astrolabe (the only known consumer) renders the highlight client-side as
a percentage-positioned overlay on top of the existing /api/v1/pdf-preview
render-on-demand path (cbcoutinho/astrolabe#76).

- pdf_highlighter: new compute_chunk_bboxes_batch() that reuses the
  existing _find_chunk_bbox text-search path, skipping all pixmap/PIL/PNG
  work.
- processor: store chunk_bbox + chunk_bbox_page in the Qdrant payload,
  drop highlighted_page_image + friends, drop the base64 import.
- visualization /api/v1/chunk-context and auth/viz_routes: read
  chunk_bbox instead of highlighted_page_image.
- vector/__init__: stop eagerly re-exporting `processor`/`scanner` —
  fixes a pre-existing circular import (search.algorithms ->
  vector.placeholder -> vector/__init__ -> processor -> scanner ->
  server.semantic -> search.bm25_hybrid -> search.algorithms partial).
  Test suite that was broken on master (test_bm25_hybrid.py et al.) now
  collects and passes.
- scripts/purge_page_images.py: ad-hoc, idempotent migration that
  delete_payload's the legacy keys from existing points. No reindex
  required; legacy chunks render the page with no overlay.

Pairs with cbcoutinho/astrolabe#76. Frontend handles missing chunk_bbox
gracefully, so this can land in either order.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
Chris Coutinho
2026-05-08 21:16:00 +02:00
co-authored by Claude Opus 4.7
parent 2e1ab99a88
commit ee402ea00e
8 changed files with 428 additions and 72 deletions
Download Patch File Download Diff File Expand all files Collapse all files
nextcloud_mcp_server/api/visualization.py
+9 -9
View File
@@ -553,9 +553,10 @@ async def get_chunk_context(request: Request) -> JSONResponse:
status_code=404,
)
# For PDF files, also fetch the highlighted page image from Qdrant if available
# This is useful for clients that want to show a pre-rendered image
highlighted_page_image = None
# For PDF files, also fetch the chunk's bounding box from Qdrant if
# available so the client can overlay a highlight on top of a
# render-on-demand page image (Deck #76).
chunk_bbox = None
page_number = chunk_context.page_number
if doc_type == "file":
@@ -563,7 +564,6 @@ async def get_chunk_context(request: Request) -> JSONResponse:
settings = get_settings()
qdrant_client = await get_qdrant_client()
# Query for this specific chunk's highlighted image
points_response = await qdrant_client.scroll(
collection_name=settings.get_collection_name(),
scroll_filter=Filter(
@@ -585,19 +585,19 @@ async def get_chunk_context(request: Request) -> JSONResponse:
),
limit=1,
with_vectors=False,
with_payload=["highlighted_page_image", "page_number"],
with_payload=["chunk_bbox", "page_number"],
)
if points_response[0]:
payload = points_response[0][0].payload
if payload:
highlighted_page_image = payload.get("highlighted_page_image")
chunk_bbox = payload.get("chunk_bbox")
# Trust Qdrant page number if available (might be more accurate than context expansion logic)
if payload.get("page_number") is not None:
page_number = payload.get("page_number")
except Exception as e:
logger.warning(f"Failed to fetch highlighted image: {e}")
logger.warning(f"Failed to fetch chunk bbox: {e}")
# Build response
response_data = {
@@ -612,8 +612,8 @@ async def get_chunk_context(request: Request) -> JSONResponse:
"total_chunks": chunk_context.total_chunks,
}
if highlighted_page_image:
response_data["highlighted_page_image"] = highlighted_page_image
if chunk_bbox:
response_data["chunk_bbox"] = chunk_bbox
return JSONResponse(response_data)
nextcloud_mcp_server/app.py
+2 -1
View File
@@ -125,12 +125,13 @@ from nextcloud_mcp_server.server import (
)
from nextcloud_mcp_server.server.auth_tools import register_auth_tools
from nextcloud_mcp_server.server.oauth_tools import register_oauth_tools
from nextcloud_mcp_server.vector import processor_task, scanner_task
from nextcloud_mcp_server.vector.oauth_sync import (
oauth_processor_task,
user_manager_task,
)
from nextcloud_mcp_server.vector.processor import processor_task
from nextcloud_mcp_server.vector.qdrant_client import get_qdrant_client
from nextcloud_mcp_server.vector.scanner import scanner_task
from nextcloud_mcp_server.vector.webhook_receiver import handle_nextcloud_webhook
logger = logging.getLogger(__name__)
nextcloud_mcp_server/auth/viz_routes.py
+12 -14
View File
@@ -604,8 +604,10 @@ async def chunk_context_endpoint(request: Request) -> JSONResponse:
f"after_len={len(chunk_context.after_context)}"
)
# For PDF files, also fetch the highlighted page image from Qdrant
highlighted_page_image = None
# For PDF files, also fetch the chunk bbox from Qdrant so the client
# can overlay a highlight on top of a render-on-demand page image
# (Deck #76).
chunk_bbox = None
page_number = None
if doc_type == "file":
try:
@@ -613,7 +615,6 @@ async def chunk_context_endpoint(request: Request) -> JSONResponse:
qdrant_client = await get_qdrant_client()
username = request.user.display_name
# Query for this specific chunk's highlighted image
points_response = await qdrant_client.scroll(
collection_name=settings.get_collection_name(),
scroll_filter=Filter(
@@ -635,22 +636,20 @@ async def chunk_context_endpoint(request: Request) -> JSONResponse:
),
limit=1,
with_vectors=False,
with_payload=["highlighted_page_image", "page_number"],
with_payload=["chunk_bbox", "page_number"],
)
points = points_response[0]
if points and points[0].payload:
highlighted_page_image = points[0].payload.get(
"highlighted_page_image"
)
chunk_bbox = points[0].payload.get("chunk_bbox")
page_number = points[0].payload.get("page_number")
if highlighted_page_image:
if chunk_bbox:
logger.info(
f"Found highlighted image for chunk: "
f"page={page_number}, image_size={len(highlighted_page_image)}"
f"Found chunk bbox: page={page_number}, "
f"rects={len(chunk_bbox)}"
)
except Exception as e:
logger.warning(f"Failed to fetch highlighted image: {e}")
logger.warning(f"Failed to fetch chunk bbox: {e}")
# Return response compatible with frontend expectations
response_data: dict = {
@@ -662,9 +661,8 @@ async def chunk_context_endpoint(request: Request) -> JSONResponse:
"has_more_after": chunk_context.has_after_truncation,
}
# Add image data if available
if highlighted_page_image:
response_data["highlighted_page_image"] = highlighted_page_image
if chunk_bbox:
response_data["chunk_bbox"] = chunk_bbox
response_data["page_number"] = page_number
return JSONResponse(response_data)
nextcloud_mcp_server/search/pdf_highlighter.py
+105
View File
@@ -691,6 +691,111 @@ class PDFHighlighter:
f"Failed to delete temp directory {temp_pdf_path.parent}: {e}"
)
@staticmethod
def compute_chunk_bboxes_batch(
pdf_bytes: bytes,
chunks: list[tuple[int, int, int, int | None, str]],
page_boundaries: list[dict],
full_text: str,
) -> dict[int, tuple[list[tuple[float, float, float, float]], int]]:
"""Compute normalized bounding boxes for chunks without rendering.
Lightweight alternative to highlight_chunks_batch — opens the PDF,
locates each chunk on its assigned page using the same text-search
path as the highlighter (`_find_chunk_bbox`), and returns
page-normalized rectangles. Skips the get_pixmap + PIL pipeline
entirely, so no PNG bytes are produced.
Args:
pdf_bytes: PDF file bytes.
chunks: List of (chunk_index, start_offset, end_offset,
stored_page_number, chunk_text). chunk_index is the dict key.
page_boundaries: Pre-computed page boundaries from the document
processor; each entry is {"page", "start_offset", "end_offset"}.
full_text: Full document text (for cross-page chunk handling).
Returns:
dict mapping chunk_index to (normalized_bboxes, page_number).
Each bbox is (x0, y0, x1, y1) in [0, 1] relative to page width
and height, top-left origin. Chunks whose bbox cannot be located
are omitted from the result.
"""
results: dict[int, tuple[list[tuple[float, float, float, float]], int]] = {}
if not chunks:
return results
temp_pdf_path = None
try:
temp_dir = Path(tempfile.mkdtemp(prefix="pdf_bbox_batch_"))
temp_pdf_path = temp_dir / "pdf.pdf"
temp_pdf_path.write_bytes(pdf_bytes)
doc = pymupdf.open(temp_pdf_path)
for (
chunk_index,
start_offset,
end_offset,
stored_page_num,
chunk_text,
) in chunks:
chunk_page_info = PDFHighlighter.find_chunk_page(
start_offset, end_offset, page_boundaries
)
if not chunk_page_info:
logger.debug(f"Chunk {chunk_index}: not found on any page")
continue
page_num = chunk_page_info["page_num"]
page_boundary = page_boundaries[page_num - 1]
page_text_length = (
page_boundary["end_offset"] - page_boundary["start_offset"]
)
# Page-relative slice (handles chunks that span page boundaries)
chunk_start_on_page = max(start_offset, page_boundary["start_offset"])
chunk_end_on_page = min(end_offset, page_boundary["end_offset"])
page_relative_text = full_text[chunk_start_on_page:chunk_end_on_page]
page = doc[page_num - 1]
bbox = PDFHighlighter._find_chunk_bbox(
page,
page_relative_text,
chunk_page_info["page_relative_start"],
chunk_page_info["page_relative_end"],
page_text_length,
)
if bbox is None:
continue
page_rect = page.rect
w = page_rect.width or 1.0
h = page_rect.height or 1.0
normalized = (
bbox[0] / w,
bbox[1] / h,
bbox[2] / w,
bbox[3] / h,
)
results[chunk_index] = ([normalized], page_num)
doc.close()
logger.info(f"Computed bboxes for {len(results)}/{len(chunks)} chunks")
return results
except Exception as e:
logger.error(f"Error computing chunk bboxes: {e}", exc_info=True)
return results
finally:
if temp_pdf_path and temp_pdf_path.parent.exists():
try:
shutil.rmtree(temp_pdf_path.parent)
except Exception as e:
logger.warning(f"Failed to clean up temp dir: {e}")
@staticmethod
def highlight_chunks_batch(
pdf_bytes: bytes,
nextcloud_mcp_server/vector/__init__.py
+9 -8
View File
@@ -1,16 +1,17 @@
"""Vector database and background sync package."""
"""Vector database and background sync package.
`processor` and `scanner` are intentionally NOT re-exported from this
package init: they transitively import `server.semantic` ->
`search.bm25_hybrid`, which forms an import cycle with
`search.algorithms` -> `vector.placeholder` -> `vector/__init__`.
Consumers that need those symbols import them from their submodules
directly (e.g. `from nextcloud_mcp_server.vector.processor import ...`).
"""
from .document_chunker import DocumentChunker
from .processor import process_document, processor_task
from .qdrant_client import get_qdrant_client
from .scanner import DocumentTask, scan_user_documents, scanner_task
__all__ = [
"get_qdrant_client",
"DocumentChunker",
"scanner_task",
"scan_user_documents",
"DocumentTask",
"processor_task",
"process_document",
]
nextcloud_mcp_server/vector/processor.py
+23 -40
View File
@@ -3,7 +3,6 @@
Processes documents from stream: fetches content, generates embeddings, stores in Qdrant.
"""
import base64
import logging
import time
import uuid
@@ -538,7 +537,9 @@ async def _index_document(
# Initialize results containers
dense_embeddings: list = []
sparse_embeddings: list = []
chunk_images: dict[int, dict] = {}
# chunk_index -> {"bbox": list[(x0,y0,x1,y1)], "page": int}
# Bboxes are normalized to [0, 1] relative to page width/height.
chunk_bboxes: dict[int, dict] = {}
# Determine if we need PDF highlighting
is_pdf = doc_task.doc_type == "file" and content_type == "application/pdf"
@@ -570,8 +571,8 @@ async def _index_document(
sparse_embeddings = await bm25_service.encode_batch(chunk_texts)
async def generate_highlights():
"""Generate highlighted page images for PDF chunks (CPU-bound)."""
nonlocal chunk_images
"""Compute chunk bounding boxes for PDF chunks (CPU-bound, no rendering)."""
nonlocal chunk_bboxes
if not is_pdf:
return
@@ -585,58 +586,39 @@ async def _index_document(
"vector_sync.pdf_size": len(content_bytes),
},
):
# Build chunk data for batch processing
# Format: (chunk_index, start_offset, end_offset, page_number, chunk_text)
chunk_data: list[tuple[int, int, int, int | None, str]] = [
(i, chunk.start_offset, chunk.end_offset, chunk.page_number, chunk.text)
for i, chunk in enumerate(chunks)
if chunk.page_number is not None
]
# Get pre-computed page boundaries from document processor
page_boundaries = file_metadata.get("page_boundaries")
if not page_boundaries:
logger.warning("No page boundaries available, skipping highlighting")
logger.warning(
"No page boundaries available, skipping bbox computation"
)
return
# Type narrowing: page_boundaries is guaranteed to be list[dict] here
page_boundaries_list = cast(list[dict[str, Any]], page_boundaries)
logger.info(
f"Batch generating highlighted page images for {len(chunk_data)} PDF chunks"
)
logger.info(f"Computing chunk bboxes for {len(chunk_data)} PDF chunks")
# Run CPU-bound highlighting in thread pool
# Pass pre-computed page boundaries and full text to avoid re-processing the PDF
batch_results = await anyio.to_thread.run_sync( # type: ignore[attr-defined]
lambda: PDFHighlighter.highlight_chunks_batch(
lambda: PDFHighlighter.compute_chunk_bboxes_batch(
pdf_bytes=content_bytes,
chunks=chunk_data,
page_boundaries=page_boundaries_list,
full_text=content,
color="yellow",
zoom=2.0,
)
)
# Convert results to storage format
for chunk_index, (
png_bytes,
actual_page_num,
highlight_count,
) in batch_results.items():
image_base64 = base64.b64encode(png_bytes).decode("utf-8")
chunk_images[chunk_index] = {
"image": image_base64,
for chunk_index, (bboxes, actual_page_num) in batch_results.items():
chunk_bboxes[chunk_index] = {
"bbox": bboxes,
"page": actual_page_num,
"highlights": highlight_count,
"size": len(png_bytes),
}
logger.info(
f"Generated {len(chunk_images)}/{len(chunks)} highlighted page images "
f"(avg {sum(img['size'] for img in chunk_images.values()) // max(len(chunk_images), 1):,} bytes)"
)
logger.info(f"Computed bboxes for {len(chunk_bboxes)}/{len(chunks)} chunks")
# Run all embedding/highlighting operations in parallel
# - Dense embeddings: I/O bound (API call)
@@ -752,14 +734,15 @@ async def _index_document(
if doc_task.doc_type == "deck_card"
else {}
),
# Highlighted page image (PDF only)
# Chunk bbox (PDF only) — normalized rectangles in [0,1]
# relative to page width/height. Replaces the legacy
# `highlighted_page_image` (Deck #76).
**(
{
"highlighted_page_image": chunk_images[i]["image"],
"highlighted_page_number": chunk_images[i]["page"],
"highlight_count": chunk_images[i]["highlights"],
"chunk_bbox": chunk_bboxes[i]["bbox"],
"chunk_bbox_page": chunk_bboxes[i]["page"],
}
if i in chunk_images
if i in chunk_bboxes
else {}
),
},
@@ -781,14 +764,14 @@ async def _index_document(
)
# Upsert to Qdrant in batches to avoid timeout with large payloads
# Each batch is limited to avoid WriteTimeout when sending large image payloads
BATCH_SIZE = 10 # ~2MB per batch with images
# Batch size kept small for safety; payloads are now small (no inline images).
BATCH_SIZE = 10
with trace_operation(
"vector_sync.qdrant_upsert",
attributes={
"vector_sync.point_count": len(points),
"vector_sync.collection": settings.get_collection_name(),
"vector_sync.images_count": len(chunk_images),
"vector_sync.bboxes_count": len(chunk_bboxes),
"vector_sync.batch_size": BATCH_SIZE,
},
):
scripts/purge_page_images.py
Executable
+136
View File
@@ -0,0 +1,136 @@
#!/usr/bin/env python3
"""Purge legacy `highlighted_page_image` payloads from Qdrant (Deck #76).
Iterates all points in the configured Qdrant collection and deletes the
legacy payload keys `highlighted_page_image`, `highlighted_page_number`,
and `highlight_count`. This relieves disk pressure caused by inline
base64 PNGs that the new code path no longer writes.
Idempotent: deleting non-existent keys is a no-op, so re-runs are safe.
Usage:
uv run python scripts/purge_page_images.py [--dry-run] [--batch-size 256]
Connection settings (Qdrant URL/API key, collection name) are read from
the same `Settings` object the server uses.
"""
from __future__ import annotations
import argparse
import asyncio
import logging
import sys
from qdrant_client import AsyncQdrantClient
from nextcloud_mcp_server.config import get_settings
logger = logging.getLogger("purge_page_images")
LEGACY_FIELDS = [
"highlighted_page_image",
"highlighted_page_number",
"highlight_count",
]
def make_client() -> AsyncQdrantClient:
settings = get_settings()
if not settings.qdrant_url:
raise SystemExit(
"qdrant_url is not configured. Set QDRANT_URL (and QDRANT_API_KEY "
"if required) before running this script."
)
return AsyncQdrantClient(
url=settings.qdrant_url,
api_key=settings.qdrant_api_key,
timeout=60,
)
async def purge(dry_run: bool, batch_size: int) -> None:
settings = get_settings()
collection = settings.get_collection_name()
client = make_client()
next_offset = None
total_seen = 0
total_updated = 0
logger.info(
"Scanning collection %s; will delete keys %s%s",
collection,
LEGACY_FIELDS,
" (dry run)" if dry_run else "",
)
while True:
points, next_offset = await client.scroll(
collection_name=collection,
limit=batch_size,
offset=next_offset,
with_payload=False,
with_vectors=False,
)
if not points:
break
ids = [p.id for p in points]
total_seen += len(ids)
if not dry_run:
await client.delete_payload(
collection_name=collection,
keys=LEGACY_FIELDS,
points=ids,
)
total_updated += len(ids)
logger.info(
"Batch: ids=%d total_seen=%d total_updated=%d",
len(ids),
total_seen,
total_updated,
)
if next_offset is None:
break
logger.info(
"Done. total_seen=%d total_updated=%d%s",
total_seen,
total_updated,
" (dry run, no writes)" if dry_run else "",
)
def main() -> int:
parser = argparse.ArgumentParser(description=__doc__)
parser.add_argument(
"--dry-run",
action="store_true",
help="Scan only; do not write any changes.",
)
parser.add_argument(
"--batch-size",
type=int,
default=256,
help="Points per scroll/update batch (default: 256).",
)
parser.add_argument(
"-v", "--verbose", action="store_true", help="Enable debug logging."
)
args = parser.parse_args()
logging.basicConfig(
level=logging.DEBUG if args.verbose else logging.INFO,
format="%(asctime)s %(levelname)s %(name)s: %(message)s",
)
asyncio.run(purge(dry_run=args.dry_run, batch_size=args.batch_size))
return 0
if __name__ == "__main__":
sys.exit(main())
tests/unit/search/test_pdf_highlighter_bbox.py
+132
View File
@@ -0,0 +1,132 @@
"""Unit tests for PDFHighlighter.compute_chunk_bboxes_batch (Deck #76).
Replaces the legacy `highlight_chunks_batch`-+-base64 pipeline that inflated
Qdrant payloads with per-chunk PNG screenshots. The new path returns
normalized bounding boxes only.
"""
from __future__ import annotations
import pymupdf
import pytest
from nextcloud_mcp_server.search.pdf_highlighter import PDFHighlighter
def _make_pdf(pages: list[str]) -> bytes:
"""Build an in-memory PDF whose pages contain the given text."""
doc = pymupdf.open()
for body in pages:
page = doc.new_page(width=595, height=842) # A4
page.insert_text((50, 50), body)
pdf_bytes = doc.tobytes()
doc.close()
return pdf_bytes
def _page_boundaries(pages: list[str]) -> tuple[list[dict], str]:
"""Build (page_boundaries, full_text) compatible with the highlighter API."""
boundaries: list[dict] = []
cursor = 0
parts: list[str] = []
for i, body in enumerate(pages, start=1):
end = cursor + len(body)
boundaries.append({"page": i, "start_offset": cursor, "end_offset": end})
parts.append(body)
cursor = end
return boundaries, "".join(parts)
def test_compute_chunk_bboxes_returns_normalized_rects():
"""Each returned bbox should be 4 floats in [0, 1] tagged with the page."""
pages = [
"Chapter 1: Introduction. Nextcloud is a self-hosted collaboration platform "
"covering installation, configuration and maintenance topics.",
"Chapter 2: Installation. Download the package, extract it to the web "
"server directory, and configure the database connection.",
]
pdf_bytes = _make_pdf(pages)
boundaries, full_text = _page_boundaries(pages)
chunks = [
(
0,
0,
len(pages[0]),
1,
"Chapter 1: Introduction. Nextcloud is a self-hosted collaboration platform.",
),
(
1,
len(pages[0]),
len(pages[0]) + len(pages[1]),
2,
"Chapter 2: Installation. Download the package.",
),
]
results = PDFHighlighter.compute_chunk_bboxes_batch(
pdf_bytes=pdf_bytes,
chunks=chunks,
page_boundaries=boundaries,
full_text=full_text,
)
assert set(results) == {0, 1}
bboxes_p1, page_p1 = results[0]
bboxes_p2, page_p2 = results[1]
assert page_p1 == 1
assert page_p2 == 2
for rects in (bboxes_p1, bboxes_p2):
assert len(rects) >= 1
for rect in rects:
assert len(rect) == 4
x0, y0, x1, y1 = rect
assert 0.0 <= x0 < x1 <= 1.0
assert 0.0 <= y0 < y1 <= 1.0
def test_compute_chunk_bboxes_empty_input():
assert (
PDFHighlighter.compute_chunk_bboxes_batch(
pdf_bytes=b"",
chunks=[],
page_boundaries=[],
full_text="",
)
== {}
)
@pytest.mark.parametrize("page_index", [0, 1])
def test_compute_chunk_bboxes_assigns_correct_page(page_index: int):
"""Verify the page number returned matches the page the chunk lives on."""
pages = [
"Page one talks about apples and oranges in detail.",
"Page two discusses bananas and grapes thoroughly.",
]
pdf_bytes = _make_pdf(pages)
boundaries, full_text = _page_boundaries(pages)
if page_index == 0:
chunk_text = "apples and oranges"
offsets = (0, len(pages[0]))
else:
chunk_text = "bananas and grapes"
offsets = (len(pages[0]), len(pages[0]) + len(pages[1]))
chunks = [(0, offsets[0], offsets[1], page_index + 1, chunk_text)]
results = PDFHighlighter.compute_chunk_bboxes_batch(
pdf_bytes=pdf_bytes,
chunks=chunks,
page_boundaries=boundaries,
full_text=full_text,
)
assert results, "expected a bbox for the chunk"
_, page_num = results[0]
assert page_num == page_index + 1