Painters keep sketches.
Writers should keep foul papers.
Write here. Every keystroke-level change is logged with a time, chained with SHA-256, and kept on this device. Later, replay the whole draft or hand over a proof file anyone can check.
Saved automatically in this browser. Nothing is uploaded.
Replay
Verify a proof file
Drop a .foulpapers.json file. The chain is recomputed in your browser: if a single character of history was edited, it breaks.
What this does and doesn't prove: the chain shows the history is internally consistent and was not edited afterwards. Timestamps come from the writer's clock; to pin them, publish the final fingerprint somewhere dated (email it to yourself, post it, commit it).