Real-time systems · 2026 · Solo — trend research, real-time architecture, protocol design, interaction design, build, verification
Sideband
A no-account peer handoff that makes direct encrypted browser transfer understandable, testable, and honest about its network boundary.
The problem
Two people in the same room or on a call sometimes need to pass a sensitive note or file without assuming a shared account, cloud drive, or approved chat workspace. Sideband turns the WebRTC offer/answer exchange into a deliberate two-pass handoff: one browser creates an invitation, the second answers it, and the resulting ordered data channel completes the transfer without a Sideband rendezvous or payload-storage service.
Architecture
Key decisions
Keep signaling visible and infrastructure honest
Sideband does not hide a coordination backend behind a peer-to-peer claim. People carry the invitation and answer through a channel they already trust; the product discloses its public STUN dependency, lack of TURN fallback, and in-transit rather than identity-authenticated encryption boundary.
Apply backpressure at the browser boundary
File frames do not flood the SCTP send queue. The sender pauses above a bounded bufferedAmount threshold, resumes on bufferedamountlow, aborts on a closed link, and surfaces a stalled transfer instead of silently dropping the user's file.
Treat the peer as untrusted input
The receiver caps declared size at 25 MB, rejects accumulated bytes beyond that declaration, resets after malformed endings, strips path and control characters from filenames, and downgrades unknown MIME types to application/octet-stream.
Make release evidence behavioral
The checked-in local two-browser scenario negotiates two peers and delivers both a message and a file. A separate no-JavaScript fallback scenario preserves the product boundary when WebRTC cannot run. GitHub records Vercel success for main SHA 214769b7eec257cb7478470e1222a2ac8e510ca3.
Translate popularity without cloning
Secure radar run 20260725-214620-github-star-radar-22034 ranked block/buzz first at 2,491 stars today, mattpocock/skills second at 1,740, and permissionlesstech/bitchat third at 1,720 (28,831 total) on 2026-07-25. Higher-ranked adjacencies failed the recent-duplicate or meaningful-outcome gates. Sideband translates bitchat's infrastructure-light peer communication demand into manual WebRTC browser handoff without copying its Bluetooth mesh, IRC surface, name, assets, or code.