The Yjs sync WebSocket had MAX_MESSAGE_BYTES = 256 KB (per frame) but
MAX_DOC_BYTES = 5 MB (per session doc). A full-state sync frame carries
the entire doc, so any session doc between 256 KB and 5 MB was allowed to
exist yet could never sync: the client's sync frame tripped the 256 KB
per-frame cap, the server closed it (1008), the client reconnected, resent
the same oversized frame, and looped forever — the UI froze, the connection
flapped Verbunden/Verbinde, and the network tab filled with 101 reconnects.
Real routes hit this fast because the BRouter geometry is stored in the doc:
a 4-waypoint, 77 km cycling route was already 305 KB.
Fix: the per-frame cap must be >= the doc cap (a full-doc sync must fit in
one frame). Set MAX_MESSAGE_BYTES = MAX_DOC_BYTES + 256 KB overhead; the
5 MB doc cap stays the real size/abuse guard. Updated the test that had
codified the inverted ordering.
Verified: planner typecheck + lint clean, yjs-server 9/9, planner suite
183/183.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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