Sending null does not clear a quality cap, contrary to the host contract
#11
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opened 2026-09-12 02:13:02 -04:00 by jared
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area: audio-pipeline
area: build-publish
area: deafen
area: decorations
area: denoise
area: livekit
area: mobile-ui
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Fork area: audio-pipeline
Fork area: build-publish
Fork area: deafen
Fork area: decorations
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Fork area: soundboard-inject
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EC fork audit 2026-09 · Medium & Low
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Reference: LotusGuild/element-call#11
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Severity: medium · Type: bug · Confidence: high
Location:
src/lotus/lotusQuality.ts:147-155,57-78; host doc/root/code/cinny/src/app/plugins/call/CallControl.ts:479-486Problem
if (v === null) settings[key] = undefined;only removes the key from the fork's sticky settings —applyToRoomthen skips patching that sender. ThemaxBitrate/maxFrameratepreviously written viasender.setParameters()is still live on the RTCRtpSender and stays there for the life of the publication. The cinny-side JSDoc explicitly documents "A field set tonullclears that cap", so the host and fork disagree: once a user lowers screenshare quality, raising it back to "auto" leaves them capped until they republish.How to trigger
setQuality({screenshareMaxBitrate: 500000}), thensetQuality({screenshareMaxBitrate: null}). Screenshare stays at 500 kbps.Suggested fix
On clear, actively write
maxBitrate: undefined/maxFramerate: undefinedinto every encoding and callsetParameters(track which keys were ever set so you only clear your own), instead of skipping the patch.Filed from the September 2026 audit (branch
lotus).Fixed in
cbd42bf9, shipped in0.25.0-lotus.1(published by CI from tag v0.25.0-lotus.1) and consumed by cinny at 9a85a487.