Hi HN! I built DCP after struggling with PDF corruption in a document workflow.

Instead of editing PDF internals (which breaks things), DCP treats the PDF as an immutable substrate and applies JSON-defined visual deltas on top.

Think of it as "Git for document surfaces" – you get: - Deterministic rendering (same input = same pixels) - Full audit trail (delta.json is human-readable) - Zero risk of corrupting the original

Would love feedback on the protocol design (SPEC.md).

I built this as an experiment after realizing that “editing PDFs” is fundamentally broken. Instead of modifying PDF internals, DCP treats PDFs as immutable surfaces and applies deterministic visual deltas (whiteout + overlay) on top. The original PDF is never modified. All edits live in a JSON delta ledger. Think: Git for 2D surfaces.

Editing PDFs is not broken.

Just because you don't understand something complex, does not mean it is broken.