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; TURN is optional extreme-network transport.
• Minimize server bandwidth. The accepted invisible ladder is direct/peer UDP, then SFU/UDP roots, then optional TURN for a selected exceptional edge, then bounded 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: production Host admission protects room creation/Host role, while a default private capability grants Viewer access to one room; public-watch is explicit. Keep raw grants out of localStorage/cookies/query/logs/SQLite; retain no account, ACL, user, or session table.
• 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 fixed-HIGH is no-go-unclassified after timing out before Viewer evidence; any revisit starts at its staged gate.
• 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 SFU roots as the primary central fallback after direct/peer UDP. The candidate has no TURN consumer or credential wire; any future exceptional-edge grant is a complete separate change. PR #12 is superseded.
• 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.
• Local reparenting is a later candidate: start with unassigned relay admission rescue; do not block current work.
• 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.
• Candidate UI has local Viewer volume/mute, copyable room codes, and a favicon. Names/roster, endpoint details, and RTP loss remain pending; no wire, media, or routing effects.
• Do not add scene detection, dynamic-FPS control, or forced AV1 without negotiation, encode, game, CPU/GPU, and sender evidence.
• ADR-0002 access is deployed: HOST_ADMISSION_PASSWORD, screener-v2, private grants/public-watch, rotate/revoke, and one nullable digest. No username/roster runtime.
• 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 89e6d7649169e43276a604c36fe681ebbed384dc deployed at 2026-08-20 09:40 +08 to https://share.bonfire.icu. It enables peer/SFU routing only for persistent room 1; unlisted rooms remain ordinary P2P. Initial-connect recovery and bounded SFU diagnostics are active, while bbe4654 is rollback-only.
• Ordinary ICE is process-wide STUN-only. Room 1 may use one LiveKit publication feeding at most two roots while retaining peer descendants; real 1/2-root media and game quality remain unverified.
• Production requires an independent HOST_ADMISSION_PASSWORD only for creation/Host role. Default private fragment grants and explicit public-watch authorize Viewers; signaling is role-bound and there are no accounts/JWT/session rows. SQLite v2 stores Host and nullable Viewer-grant digests; all four rooms, including room 1, survived the stopped migration.
• Production uses nginx, Node.js 24.19.0, coturn 4.17.2 for STUN/rollback, and pinned LiveKit 1.13.5 on UDP 7882 with TCP fallback disabled. Screener and LiveKit report NRestarts=0; local/public health and index-2HASsWrj.js return 200, while /rtc, /rtc/validate, and unauthenticated /rtc/v1 return 404 outside the SPA. Public TCP 7880/7881 is blocked; LiveKit has a 192/256 MiB cgroup boundary and no automatic restart.
• Old TURN parser/signer/refresh/UI/SNI artifacts are absent; coturn and the old release are rollback-only, not candidate media.
• 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.
• Production logs show two root participants and two short Host participants with no service restart or retained track. Their timing is consistent with, but does not directly prove, one fresh-grant retry and Peer failback. The Host exposes only the local current-revision failure stage (connect|source|video-publish|sender-config|audio-publish|transport) and uploads no raw error or endpoint data. Browser relays still re-encode; native sharing remains outside product code.
• The retained v1 backup is the only schema rollback path. A failed artifact attempt exposed unsafe hard-linked dependency reuse; the successful immutable release has zero shared regular-file inodes with rollback, and future releases preserve that boundary.
• 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.
• Native drafts remain experiments: one WebCodecs object is not hardware proof; stock GCC+RTX is no-go.
• 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. It is unverified; test zero-child leaves, then root evacuation before broad rollout.
• Local Host A+B aligns one capture/outbound/transport generation; authenticated Viewer C adds a sanitized, read-only P2P window and fails closed for stale, ambiguous, or SFU-fed evidence. It retains no raw fmtp/SDP/stats and performs no media action. Topology classification remains absent.

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 measured restrictive-network demand justifies a future selected-edge TURN grant at all, and which UDP transport/port it would use. The current candidate does not retain dormant TURN or media-TCP configuration.
• 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.
• Exact evidence thresholds/windows and the native hardware matrix for ADR-0007; #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/