MultiRoombaRover/perf/spectate-issues/005-shared-log-session-stream-pressure.md

Issue 005: Shared Log And Session Stream Pressure

Summary

/spectate receives a large volume of shared live socket traffic, especially log:entry, session:sync, sensorFrame, and commandAck. Some of this will likely be fixed by the / backlog, but it remains important for /spectate because the route keeps logs/chat visible in the sidebar while also rendering multiple live media feeds.

Severity

Medium.

This is not as spectate-specific as the HUD map or WebRTC fan-out issues, but it adds steady parsing, state, and render pressure.

Upstream Likelihood

High for logs and shared session pressure.

If the / work implements log batching, log virtualization, selector-based session updates, and chat/nickname churn reduction, a lot of this issue should improve without special /spectate changes.

Related upstream issues:

perf/issues/003-high-volume-log-stream.md
perf/issues/006-chat-and-nickname-churn.md
perf/issues/007-timers-and-polling.md
perf/issues/004-sensor-telemetry-render-frequency.md

Affected Files

• webui/src/context/SessionContext.jsx
• webui/src/spectate/SpectatorApp/SpectatorContent.jsx
• webui/src/spectate/SpectatorApp/components/LogsRow.jsx
• webui/src/components/ChatPanel/index.jsx
• webui/src/components/RawUserPilePanel/index.jsx
• webui/src/components/RoverQueuesPanel/index.jsx
• server log/session emitters

Evidence

Artifact:

perf/results/2026-06-12T04-55-16-888Z-root-runtime/root-runtime-report.json

30s sample:

log:entry events:      634
log:entry bytes:       150,179
session:sync events:    54
session:sync bytes:     914,000
commandAck events:      68
chat:init bytes:        77,415
log:init bytes:         44,530

Text and input mutations also appeared:

Text characterData mutations:                164
input.field-input.flex-1 name mutations:     102
input.chat-composer-input name mutations:    102

The input-name churn matches the same type of sidebar/chat behavior observed on /.

Current Code Path

SpectatorContent keeps these mounted:

webui/src/spectate/SpectatorApp/SpectatorContent.jsx:88
<ChatPanel allowSpectatorInput ... />

webui/src/spectate/SpectatorApp/SpectatorContent.jsx:91
<LogsRow ... />

webui/src/spectate/SpectatorApp/SpectatorContent.jsx:79
<RoverQueuesPanel title="Rovers" />

webui/src/spectate/SpectatorApp/SpectatorContent.jsx:68
<RawUserPilePanel ... />

That is useful spectator UI, but it means /spectate pays for general page state while also paying for media and telemetry.

Why This Matters

Logs and session syncs are deceptively expensive:

• socket payloads must be parsed
• state must be updated
• arrays/lists may be copied
• list components may rerender
• text/input attributes may mutate

This becomes worse on /spectate because the route is not just a dashboard. It is also a multi-feed media surface.

Fix Strategies

Option A: Reuse The / Log Fix

The / log issue should probably introduce:

• batching log updates
• capping retained logs
• virtualizing or windowing visible rows
• pausing log rendering when collapsed/offscreen
• separating log ingestion from log rendering

Apply the same path to LogsRow.

Option B: Make Spectator Sidebar Panels Independently Subscribed

The rover media grid should not rerender because logs/chat/users changed. This overlaps with issue 004.

Option C: Lower Or Gate Command/Log Visibility For Mobile

On mobile spectator layout, logs are less important than video health. Options:

• collapse logs by default
• batch logs while collapsed
• show only warning/error logs by default
• update visible logs at 1-2Hz

Option D: Reduce session:sync Payload Churn

If the server sends full session snapshots frequently, consider:

• event-specific deltas for high-frequency branches
• preserving client-side branch references for unchanged data
• moving logs/chat out of the broad session path if they are currently coupled

Recommended Path

Do not start here if you are working the / list first. Fix the / log/session/chat items, then rerun /spectate and reassess.

If still hot on /spectate:

1. Make LogsRow batch/virtualize/collapse.
2. Keep the media grid isolated from sidebar state.
3. Add a mobile spectator mode that reduces log rendering frequency.

Validation

Run:

CPU_THROTTLE=6 VIEWPORT=390x844 MOBILE=1 SAMPLE_MS=30000 \
  node perf/live-root-runtime-audit.mjs https://rover.otter.land/spectate perf/results

Expected improvements:

• Lower Text:characterData mutations.
• Fewer added/removed DOM mutation bursts.
• Lower ScriptDuration.
• log:entry socket count may remain high if only rendering is batched.

Risks

• Logs are operationally useful; do not hide critical warnings.
• If batching is too aggressive, the UI can feel stale.
• Be careful not to mix log ingestion throttling with log display throttling. Usually, display throttling is safer.