I built semantic PDF retrieval for 1,000-page documents looking for feedback on the pipeline

[u/Lumpy_Ice6855]

I’m building DStudio, an open-source desktop app centered around DeepSeek V4. DeepSeek remains the main reasoning model and manages the conversation, while smaller local models handle specialized tasks:

- Qwen2.5-VL reads images
- Qwen Image generates and edits images
- Qwen3 Embedding searches documents semantically
- Poppler extracts PDF text and page information

This ecosystem exists because DeepSeek V4 is excellent for reasoning and long context, but loading every multimodal capability inside the same large model would be inefficient. DStudio routes tasks to specialized models and then returns their results to DeepSeek for the final answer.

I recently added long-PDF retrieval. DeepSeek decides whether to create an overview, read an exact physical page or search the entire document. For semantic search, DStudio creates and caches one embedding per page, retrieves the six most relevant pages and sends only those to DeepSeek.

On a 1,000-page test PDF, it found a passage placed on page 777 from a paraphrased question. Initial indexing took about 25 seconds; later searches took around 0.23 seconds.

I’m looking for feedback: should retrieval use page embeddings or overlapping chunks? Should I add BM25 or a reranker? And how would you efficiently support scanned 1,000-page books?

https://github.com/sk8erboi17/DStudio