zhtx2024/dsh-pdf

PDF parsing toolkit for DeepSeek Harness — three agent-facing tools (pdf_info / pdf_extract_text / pdf_render_page) with hybrid engines, including system-font rendering for PDFs with non-embedded CJK fonts (e.g. EasyEDA / JLC EDA schematic exports).

English | 中文

Tags: dsh-plugin · pdf · pdfjs · canvas · schematic · tools

Install

dsh plugin --profile web add @zhtx2026/dsh-pdf

Or from a local checkout during development:

dsh plugin --profile web add link:<path-to-repo>

Then restart DSH (or open a new session) — the three tools and an agent guidance block become available.

Tools

Tool	What it does
pdf_info	Page count, page sizes (pt), document metadata, and the font list with per-font embedded flags.
pdf_extract_text	Extracts text per page; optional page and withPosition (per-line x/y coordinates + font size).
pdf_render_page	Renders one page to a PNG (local file) with configurable scale/outDir; engine auto-selection.

Why a custom renderer?

pdfjs-dist cannot render text in PDFs whose fonts are not embedded and lack a ToUnicode map — the classic case is JLC EDA / EasyEDA schematic exports (SimSun/SimHei Type0 fonts with UniGB-UCS2-H encoding): pdfjs emits translateFont failed and drops the glyphs.

dsh-pdf solves this with a two-engine design:

• pdfjs engine — used when all fonts are embedded (standard PDFs).
• sysfont engine — a built-in content-stream renderer that decodes the PDF text operators (BT/ET, Tf, Tm, Td, Tj, TJ) itself, maps UniGB-UCS2-H/UTF-16BE strings to Unicode, and draws them with system fonts (SimSun, SimHei, Microsoft YaHei, …) via @napi-rs/canvas.

Text extraction uses the same auto-selection: embedded fonts → pdfjs text layer; non-embedded fonts → the built-in decoder (which correctly recovers CJK text pdfjs loses).

Example

pdf_info("D:/Downloads/SCH_SA-V11A.pdf")
→ 3 pages, A3 landscape, jsPDF producer, 6 fonts (all non-embedded)

pdf_extract_text("D:/Downloads/SCH_SA-V11A.pdf", { page: 1 })
→ net names, pin numbers, and Chinese labels ("主控板", "嘉立创", …)

pdf_render_page("D:/Downloads/SCH_SA-V11A.pdf", { page: 1, scale: 2 })
→ D:/Downloads/SCH_SA-V11A-pages/page-1.png  (2396×1698, engine: sysfont)

Architecture

• lib/index.js — cordis plugin entry (name, inject, apply); registers the three tools as native tool objects (plain JSON-Schema parameters and output — no @deepseek-ai/dsh-tools dependency needed) and injects the agent guidance block (systemPrompt.section, order 160).
• lib/pdf-core.js — self-contained engine: PDF object parser, font scanner, pdfjs loading with fs-based CMapReaderFactory/StandardFontDataFactory (Node 24's global fetch doesn't speak file://), the built-in text extractor, and the sysfont renderer.
• cordis.patch.yml — the dsh.bundle.patch insert row.

Limitations

• Scanned/image-only PDFs have no text layer — extraction returns nothing (rendering still works, as a plain image).
• The sysfont renderer assumes Type0 CID codes equal Unicode code points (true for UniGB-UCS2-H exports); exotic CID fonts fall back to pdfjs.
• Large PDFs are parsed fully into memory.

License

MIT