Piik/docs/project-memory.md

Project Memory

Last updated: 2026-08-20

Confirmed Intent

• Build low-latency game sharing for one broadcaster and trusted friends; public or large broadcasts belong on OBS/Twitch-class services.
• Viewers join from normal desktop/mobile browsers. A later native sender may share encoding and improve capture/audio without changing the Web viewer requirement.
• Use a small central service for access, rooms, signaling, deterministic topology, STUN, observability, and bounded SFU-root capacity.
• Minimize server bandwidth. Ordinary peer ICE is STUN-only. Failure tries restart, rebuild, alternate peer and bounded SFU/UDP roots; only then may the controller authorize short-lived TURN for one selected exceptional edge before clear failure. TURN is transport, not topology.
• Non-server nodes have at most two downstream edges; browser relays stay at one until resource gates pass. SFU normally feeds one or two roots that retain peer descendants; separately capped server edges may serve exceptional viewers that cannot attach behind a healthy root.
• Two-tree packet/layer striping may reduce endpoint upload toward one stream bitrate, but needs a bounded multi-parent, loss, sync, churn, and latency experiment; it is not in the current full-stream chains.
• Direct/peer keeps per-PC stock GCC. SFU paths start at a HIGH ceiling and share at most one LOW; next test LiveKit exactly-two built-in BWE on zero-descendant leaves. If it passes, no app media selector is built. Explicit quality, manual activation, then custom/native are later fallbacks; always-on LOW needs resource gates.
• A later explicit quality fallback evacuates children under a generation guard first. Autonomous BWE enters suspect; confirmation evacuates children, and no confirmed FALLBACK parent remains. Root-with-children impact is a default-on gate; capacity returns after longer recovery plus cooldown. Self-report alone never triggers it.
• Separate abuse control from watching: Host admission protects creation/Host; private Viewer entry uses a room grant or optional room password, while public-watch accepts the code. Persist neither raw credential; keep accounts, ACLs, users, and session tables out.
• Keep decisions, snapshots, research, code, AGENTS.md, and .codex/ in Git; rewrite memory/status in place. Research current primary sources before material work and reject speculative machinery.
• Migrate client, server, and deployment atomically. After a canary, delete superseded config/wire/parsers/tests; do not retain compatibility layers, dual writes, or a second architecture without a current consumer. Git history owns the old implementation.
• Autonomously deploy each coherent low-risk milestone after narrow tests, independent review, one full gate, CI and rollback preflight. Keep protocol/database migrations atomic rather than folding them into routine UI/media updates.

Current Recommendation

• Keep desktop Chrome/Edge and the responsive Web viewer as the baseline. Validate Android Chrome and iOS Safari as leaves.
• Use direct host P2P for one or two viewers. Keep ADR-0004 off broadly; use an isolated exact-room candidate until resource, quality, recovery, SFU/UDP, bounded-failure, and browser/mobile gates pass.
• Browser relays resend remote MediaStreamTrack values and re-encode at each hop; WebRTC does not guarantee a shared encoder across peer connections, so measure the cost.
• Keep experiments bounded: the standard representation sequence is below; native RTP relay, encoded-object striping, and FEC remain separate.
• ADR-0006 remains no-go for expansion. A Chrome 151 loopback proves fixed VP8 WebCodecs -> Go RTP -> one 1280x720 Viewer: 30 sender frames/85 source RTP packets, 877 inbound packets, 299 decoded and rendered, no fatal. Pion outbound delta was not retained because its 2-second diagnostics snapshot did not refresh. Hardware, multi-viewer/FIFO, endurance, public-network, and packaged-native proof remain open. Source fixes timestamp overlap from nullable duration; the separate MF RTX fixture still misses Pion fmtp. Native v2 remains memory-only and leaves SQLite/Web unchanged.
• Mobile Web Host is unsupported; feature-detect and fail clearly. Mobile Viewer stays leaf-only. After Windows native, gate Android 14+; iOS waits for stable iOS 27 ScreenCaptureKit.
• ADR-0005 accepts direct/peer UDP, bounded SFU roots, then optional selected-edge TURN. Source has a default-off, undeployed one-shot rebuild after SFU; participant-wide TURN remains rejected and production stays STUN-only.
• Keep the controller exact-room only: room 1 is the STUN/SFU smoke. Preserve sticky progressing P2P, mobile leaves and break-before-make. Recovery spends one attempt per layer (ICE restart, same-parent rebuild, alternate peer, then SFU), never three identical retries; active SFU gets one fresh grant before Peer failback.
• C+B quality reparenting is edge-local and cooldown-bound; no score, timer, or global parent penalty.
• Flagship media is UDP; HTTPS/WSS stays TLS/TCP; the old release remains rollback-only.
• Treat settings as ceilings and degradation as unclassified. Use correlated Host A+B/Viewer C and one-variable evidence; never force AV1, infer by UA, or create a composite score.
• Production reports poor film audio and self-echo when system capture includes voice software. Diagnose audio A/B/C and sync; Web cannot isolate arbitrary processes and maxBitrate is not quality-up. A Windows 11 native candidate defaults to game-process-tree audio and never widens silently; Windows 10 remains unresolved/unsupported. See docs/research/browser-screen-audio-quality.md.
• Viewer-local names and the opt-in Web participant roster remain control-plane-only. The Web Host name change is source-only after its failed activation; names stay socket/localStorage-only, and Native remains outside the capability boundary.
• Do not add scene detection, dynamic-FPS control, or forced AV1 without negotiation, encode, game, CPU/GPU, and sender evidence.
• ADR-0002 grant/public access and the v3 room-password migration are deployed; Host display-name remains source-only. Names/presence remain session-only without account or roster tables.
• Deferred architecture audit: docs/maintenance.md.

Current Implementation

• The repository is one npm package using Node.js 24, React, TypeScript, Vite, native WebRTC, ws, Zod, Vitest, and separate coturn.
• Production currently serves fdd14ba0d9b5ea4c43aa0f6a3a29e0eacf182612 at https://share.bonfire.icu after the single Host display-name cutover attempt at 2026-08-20T16:09Z was automatically rolled back. The prepare-to-release switch and health gate passed; a post-cutover assertion used stale NRestarts=31 data and triggered the rollback. Health is 200 and SQLite v3 retains four rooms including room 1. Room 1 alone enables peer/SFU routing, C+B local reparenting, and admission rescue; unlisted rooms remain ordinary P2P. The preceding 31bee238 release remains historical rollback evidence.
• The current Screener, LiveKit, coturn, and nginx services each report NRestarts=0. The Host display-name artifact was not retained as an active release, so Host names remain source-only/not deployed; selected-edge TURN remains disabled.
• Production ICE is STUN-only; stale PEER_ICE_TURN_* keys fail startup even blank. Source has a default-off coturn REST rebuild for the original failed Host/ViewerRelay edge after Viewer-root SFU exhaustion; it is undeployed/unverified and production advertises no TURN credential.
• Production requires an independent HOST_ADMISSION_PASSWORD only for creation/Host role. Default private fragment grants, room passwords, and explicit public-watch authorize Viewers; four anonymous Chrome routes stayed neutral until authorization. There are no accounts/JWT/session rows; SQLite v3 still contains all four rooms, including room 1.
• Production uses nginx, Node.js 24.19.0, coturn 4.17.2, and pinned LiveKit 1.13.5 on UDP 7882 with TCP fallback disabled. The application TURN tuple is absent; coturn retains the old authenticated-relay config and TCP/UDP 3478 plus UDP 49152-49251 rules but receives no advertised credential. Current service state is health 200 with all four service restart counts at 0.
• ADR-0005 is configured with exact PEER_ASSISTED_ROOM_IDS=1; unlisted rooms use ordinary P2P. screener-v2 is the only deployed signaling literal; there is no v1 parser or translator.
• Chrome 151/LiveKit localhost A/B cut failure-to-active/render from 1.481/2.257 seconds to 0.200/0.320; 31 new frames and 25 ms sampling kept host edges at two. It is headless synthetic 720p30 and includes SDK/network prewarm, not public-network evidence.
• Chrome 151 synthetic topology/quality-control runs kept fanout 2/1 and all viewers decoding; one relay close recovered in 5.32 seconds. This is control evidence only.
• Room 1 publishes HIGH+LOW with Dynacast off and subscriber HIGH ceilings, and now has bounded local quality reparenting. Both remain unverified on real media; test zero-child leaves and calibrated C+B loss before broad rollout.
• C+B uses three hard-bad pairs, one-use samples and guarded intent/cooldown. Deployed admission rescue moves the oldest childless zero-capacity Host leaf below an unassigned one-slot relay in one revision; no score/timer/global rebalance. Deployment passed, but no real room triggered it.
• Source-only Web Host name/presence leaves Native wire/media unchanged and separates Viewer roster from Host diagnostics; the Host-name artifact was not activated.

Provisional Quality Targets

• Controlled direct path at RTT no more than 40 ms and loss no more than 1%: glass-to-glass p50 no more than 150 ms and p95 no more than 250 ms.
• Regional SFU/UDP roots under the same endpoint conditions: glass-to-glass p95 no more than 350 ms; optional TURN is measured separately.
• First picture within 3 seconds after a watch request, excluding explicit permission time.
• A 60 fps profile must not remain below 50 decoded fps for more than 5 seconds without a visible downgrade or limiting reason.

These are measurement gates, not performance claims.

Open Decisions

• Sustainable count by hardware, quality, network, and route: finish instrumented 1/3/5/8, then pass a 20-viewer matrix before changing the accepted target default to 20.
• Whether ADR-0004 passes fanout, re-encoding, depth-four latency, reparenting, silent-partition, and mobile-leaf gates.
• Whether source-complete selected-edge passes forced relay, expiry/failure, mobile, 1-GiB resource and relay-bandwidth gates. Coturn's bearer is non-revocable until expiry; application guards and TTL only bound reuse. Performance comparison and the retained matrix follow functional landing; Media TCP is out of scope.
• Exact mobile lifecycle behavior and whether Windows per-application audio is required for the first release.
• Project license and distribution model, which determines whether GPL/AGPL sources can move beyond study-only use.
• Initial deployment regions and expected mainland China, Hong Kong, and overseas network mix.
• Whether voice chat ever enters scope or Screener stays complementary to an existing voice application.
• Production calibration of local-reparent thresholds and the ADR-0007 native matrix; #28's minimum-of-two rule is not a candidate.

Source Of Truth

• Documentation index and current phase: docs/README.md and docs/status.md
• Requirements and design: docs/需求理解.md and docs/方案设计.md
• Media research: docs/research/, indexed by docs/README.md
• Architecture: ADR-0001/0002, proposed ADR-0004, accepted-but-unverified ADR-0005, no-go proposed ADR-0006, accepted ADR-0007, and rejected/superseded ADR-0003
• Deployment and maintenance: docs/deployment.md, docs/maintenance.md, AGENTS.md, and .codex/