Bug fixes 4 6 2026#4
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…n on map Root Cause fetchLatest() had 5 early-return paths that didn't refresh the Redis TTL for existing scans: 1. S3 listing returns HTTP error 2. S3 listing has no contents (happens at UTC date rollover) 3. No V06/V08 volume files found 4. File timestamp parse fails 5. Station data >30 min old (stale) ← the most common trigger Since SCAN_TTL and MAX_AGE_MS are both 30 minutes, once a station's S3 data ages past 30 minutes the TTL stops being refreshed, and the scan expires from Redis within the remaining TTL window. At z8+ there's no MRMS fallback (tilers produce z2-7 only), so expired scans = transparent tiles. The previous fix (commit 4e01caf) increased TTL from 10 to 30 minutes — this delayed the symptom from ~10 min to ~30 min but didn't address the root cause. Changes src/nexrad/main.ts — Unconditionally refresh TTL for previously-ingested stations at the top of fetchLatest(), before any S3 work. This single line covers all failure paths (stale data, S3 errors, network issues, date rollover). The .catch(() => {}) prevents Redis connection errors from blocking the fetch attempt. src/server/nexrad-scan-provider.ts — Wrap readScanFromRedis in try/catch so Redis connection blips don't crash tile requests (defense-in-depth).
Two changes across both public/index.html (the app) and landing/index.html (the homepage): 1. Replaced 375K Leaflet calls per frame with inline math The old code called map.latLngToContainerPoint() for every trail point of every particle — 15,000 particles × 25 trail points = 375,000 calls per frame. Each call created 3 Leaflet objects and did full Mercator projection math, generating ~1.1M garbage objects per frame for the GC. The fix stores trails in normalized Mercator coordinates (nx = lon/360 + 0.5, ny via a single log/tan), extracts the map transform once per frame with a single Leaflet call, then converts all trail points with just x = nx * scale + ox (multiply + add). Same visual result, ~100x less work. 2. Batched canvas draw calls by color The old code did a separate beginPath() / stroke() for each particle — 15,000 stroke() calls per frame. Each stroke() triggers rasterization. The fix bins particles by their color index, then draws each color group with a single beginPath() / stroke(). Reduces draw calls from ~15K to ~20. 3. Removed the pause/resume mechanism The old code froze the animation on movestart/zoomstart and resumed on moveend/zoomend. This caused the visible "freeze then recalculate" behavior. With the inline math being fast enough (~2-4ms per frame vs the old ~50ms), the animation now runs continuously during pan/zoom with no pause needed.
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Summary
Closes #1
Closes #2
Changes
latLngToContainerPointcalls with inlineMercator math (1 Leaflet call + multiply/add per trail point), batch canvas
stroke()calls by color (15K → ~20), removepause/resume mechanism so wind flows continuously during interaction
work — prevents scans from expiring through stale data, S3 errors, date rollover, or network failures
getScanso connection blips don'tcrash tile requests
Testing
npx tsc --noEmitpassesdocker compose upScreenshots
N/A — no visual design changes, only performance and reliability fixes.