go-synctex — a pure-Go parser for TeX's SyncTeX (source ↔ PDF), no cgo

go-synctex is a pure-Go (no cgo) parser for SyncTeX, the .synctex.gz file TeX engines (pdflatex / xelatex / lualatex) emit to link a .tex source line to the exact spot on the PDF page — in both directions. It answers forward queries ((file, line) → (page, x, y): jump the viewer to where a line was typeset) and backward queries ((page, x, y) → (file, line): click a glyph and jump back to the source). It depends on nothing but the standard library, guards against hostile input with a decompression-size cap, and can scope Input: paths to a project root so absolute host paths never leak to a client — 100% coverage, CI green across 6 arches.

SyncTeX file parsing ready

Reads .synctex.gz (and plain .synctex): the Version / Input:tag:path map, the Content: block, {page blocks and the node records ([, h, v, k, g, x) with their N,L:X,Y anchor prefix, up to Postamble:.

Forward search ready

(source file, line) → (page, x, y). Records are indexed per source file and binary-searched for the nearest line ≥ the query, so an editor can jump the PDF viewer to where a line was typeset.

Backward search ready

(page, x, y) → (source file, line). Picks the record closest to a clicked PDF coordinate, so a viewer can jump back to the source that produced a glyph — the full round-trip.

Hardening & path scoping ready

A 32 MB decompression cap defeats zip-bomb .synctex.gz inputs; WithProjectRoot drops Input: paths outside the project root and rewrites in-root paths relative-to-root so absolute host paths never leak to a client.

Coordinates & coverage ready

Anchors are exposed as raw SyncTeX scaled points (sp; PDF points = sp / 65536) so callers apply their own point/DPI scaling. 100% coverage including every error branch, gofmt + go vet clean, green across all six 64-bit Go arches.

Typed sp/point helpers & box dimensions planned

Possible future surface: a typed scaled-point/PDF-point helper, parsing the trailing W,H,D box dimensions (only the anchor is read today), and a streaming parse API for very large jobs.

ready capability complete (exit criteria met, nothing material left)
active in progress (substantial work shipped, not yet finished)
planned not started yet (or downstream by design)

A pure-Go, cgo-free parser for TeX's SyncTeX output, so it cross-compiles and embeds anywhere — inside an editor, a PDF viewer, or a build server — with nothing to install alongside it. It reads .synctex.gz and plain .synctex, indexes the records, and answers forward (source → PDF) and backward (PDF → source) queries, exposing anchors as raw SyncTeX scaled points so callers apply their own point/DPI scaling. Hardened against zip-bomb inputs and untrusted Input: paths, at 100% coverage across the six 64-bit Go targets. Part of github.com/go-synctex.