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fix: cache /data metrics for instant reload #901

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fix: cache /data metrics for instant reload #901

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c68b5bb
fix: cache /data metrics and point copy at global_stats
riderx Jul 16, 2026
9505b1a
fix: restore public /data copy
riderx Jul 16, 2026
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Binary file added .github/pr-assets/data-page-cache-global-stats.webp
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48 changes: 43 additions & 5 deletions apps/web/src/pages/data.astro
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Original file line number Diff line number Diff line change
Expand Up @@ -304,19 +304,57 @@ const content = {
}
}

async function loadMetrics() {
const METRICS_CACHE_KEY = 'capgo-live-update-metrics-v1'
const METRICS_CACHE_TTL_MS = 5 * 60 * 1000

function readCachedMetrics(): Metrics | null {
try {
const raw = sessionStorage.getItem(METRICS_CACHE_KEY)
if (!raw) return null
const parsed = JSON.parse(raw) as { savedAt?: unknown; payload?: unknown }
if (typeof parsed.savedAt !== 'number' || Date.now() - parsed.savedAt > METRICS_CACHE_TTL_MS) return null
return normalizeMetrics(parsed.payload)
Comment on lines +315 to +316

@coderabbitai coderabbitai Bot Jul 16, 2026

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🎯 Functional Correctness | 🟡 Minor | ⚡ Quick win

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
set -euo pipefail

# Map the relevant file and inspect the metrics cache logic.
printf '\n== file list ==\n'
git ls-files 'apps/web/src/pages/data.astro' 'apps/web/src/**/config*' 'apps/web/src/**/*metrics*' | sed 's#^`#-` #'

printf '\n== relevant lines in apps/web/src/pages/data.astro ==\n'
nl -ba apps/web/src/pages/data.astro | sed -n '260,340p'

printf '\n== search for METRICS_CACHE_TTL_MS and savedAt usage ==\n'
rg -n "METRICS_CACHE_TTL_MS|savedAt|normalizeMetrics|cache" apps/web/src/pages/data.astro apps/web/src -g '!**/dist/**' -g '!**/build/**' || true

Repository: Cap-go/website

Length of output: 565

🏁 Script executed:

#!/bin/bash
set -euo pipefail

printf '\n== data.astro excerpt ==\n'
sed -n '280,340p' apps/web/src/pages/data.astro

printf '\n== savedAt / metrics cache references ==\n'
rg -n "savedAt|METRICS_CACHE_TTL_MS|normalizeMetrics|metrics cache|cache" apps/web/src/pages/data.astro apps/web/src -g '!**/dist/**' -g '!**/build/**' || true

Repository: Cap-go/website

Length of output: 50370

🏁 Script executed:

#!/bin/bash
set -euo pipefail

sed -n '300,335p' apps/web/src/pages/data.astro

printf '\n--\n'

rg -n "savedAt|METRICS_CACHE_TTL_MS|normalizeMetrics" apps/web/src/pages/data.astro

Repository: Cap-go/website

Length of output: 2069

Reject future-dated cache entries. savedAt values ahead of Date.now() bypass this TTL check, so stale metrics can be treated as fresh when revalidation fails. Add a savedAt <= now guard before accepting the cache.

🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@apps/web/src/pages/data.astro` around lines 315 - 316, Update the cache
validation around parsed.savedAt in the metrics cache parsing flow to capture
the current time and reject entries whose savedAt is later than that time, in
addition to the existing type and TTL checks. Only call normalizeMetrics for
non-future, non-expired entries.

} catch {
return null
}
}

function writeCachedMetrics(payload: unknown) {
try {
sessionStorage.setItem(METRICS_CACHE_KEY, JSON.stringify({ savedAt: Date.now(), payload }))
} catch {
// Ignore quota / private-mode failures.
}
}

async function fetchMetrics() {
if (!endpoint) throw new Error('Missing metrics endpoint')
const controller = new AbortController()
const timeoutId = window.setTimeout(() => controller.abort(), 10_000)
try {
if (!endpoint) throw new Error('Missing metrics endpoint')
const response = await fetch(endpoint, { headers: { Accept: 'application/json' }, signal: controller.signal })
const metrics = response.ok ? normalizeMetrics(await response.json()) : null
const payload = response.ok ? await response.json() : null
const metrics = normalizeMetrics(payload)
if (!metrics) throw new Error('Invalid metrics response')
writeCachedMetrics(payload)
return metrics
} finally {
window.clearTimeout(timeoutId)
}
}

async function loadMetrics() {
const cached = readCachedMetrics()
if (cached) {
renderMetrics(cached)
page?.setAttribute('aria-busy', 'false')
}
try {
const metrics = await fetchMetrics()
renderMetrics(metrics)
} catch {
renderUnavailable()
if (!cached) renderUnavailable()
} finally {
window.clearTimeout(timeoutId)
page?.setAttribute('aria-busy', 'false')
}
}
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