Subchapter 7.109

Impact Label

Gate Investigations

Merge Signals

85 more in the appendix

Impact Label

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126

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Source

lib/impact-label.mjs

JavaScript126 lines5 KB

1import { impactMagnitude } from './impact-magnitude.mjs';
2
3const SLOW_ROUTE_P95_THRESHOLD_MS = 500;
4const CACHE_HIT_THRESHOLD_PCT = 50;
5const COLD_START_THRESHOLD_PCT = 40;
6const RELIABILITY_TARGET_PCT = 0.1;
7
8export function computeImpactLabel(rec,

impact-label.mjs on GitHub

signals

=

{}) {

const il = rec?.impactLabel ?? {};

if (il.performance) return il.performance;

if (il.costPhrase) return il.costPhrase;

if (typeof rec?.estimatedSavingsUsd === 'number' && rec.impactTier) {

const magnitude = impactMagnitude({

currentCost: rec.estimatedSavingsUsd,

impactTier: rec.impactTier,

});

return magnitude.phrase;

}

return synthesizeImpactFromSignal(rec, signals);

}

export function synthesizeImpactFromSignal(rec, signals = {}) {

const tier = rec?.impactTier;

const sig = [

rec?.o11ySignal,

rec?.evidence?.o11ySignal,

rec?.why,

rec?.what,

].filter((v) => typeof v === 'string' && v.trim()).join('\n') || null;

if (!sig || !tier) return null;

const m = String(sig);

const inv = parseSigNumber(m, /inv=([\d,]+)/);

const p95 = parseSigNumber(m, /p95=([\d,]+)ms/);

const cachePct = parseSigNumber(m, /cache=([\d.]+)%/);

const coldPct = parseSigNumber(m, /cold=([\d.]+)%/);

const buildSharePct = parseSigNumber(m, /build_minutes_share=([\d.]+)%/i) ??

parseSigNumber(m, /build(?: CPU)? minutes share:?\s*([\d.]+)%/i);

const errors = parseSigNumber(m, /errs=([\d,]+)/);

const errorRatePct = parseSigNumber(m, /rate=([\d.]+)%/);

const writes = parseSigNumber(m, /writes=([\d,]+)/);

const reads = parseSigNumber(m, /reads=([\d,]+)/);

const cwvIssues = [

cwvIssue('LCP', parseSigNumber(m, /LCP=([\d.]+)ms/i), 2500, 'ms'),

cwvIssue('INP', parseSigNumber(m, /INP=([\d.]+)ms/i), 200, 'ms'),

cwvIssue('CLS', parseSigNumber(m, /CLS=([\d.]+)/i), 0.1, ''),

].filter(Boolean);

if (cwvIssues.length > 0) {

return `${tier} impact — bring ${joinEnglish(cwvIssues.map(formatCwvIssue))}.`;

}

if (errors != null && errorRatePct != null) {

const reductionPct = Math.ceil(Math.max(0, (1 - (RELIABILITY_TARGET_PCT / errorRatePct)) * 100));

return `${tier} impact — cut 5xx rate by ~${reductionPct}% to get below ${RELIABILITY_TARGET_PCT}% (current ${errorRatePct}%, ${formatInteger(errors)} errors in this window).`;

}

if (errors != null) {

return `${tier} impact — resolve ${formatInteger(errors)} billed 5xx errors in this window.`;

}

if (cachePct != null && inv != null) {

if (cachePct < CACHE_HIT_THRESHOLD_PCT) {

return `${tier} impact — current cache hit rate is ${cachePct}% across ${formatInteger(inv)} requests in this window; the gate fires below ${CACHE_HIT_THRESHOLD_PCT}%.`;

}

if (p95 == null) {

return `${tier} impact — current cache hit rate is ${cachePct}% across ${formatInteger(inv)} requests in this window; this recommendation targets the remaining uncached traffic.`;

}

if (writes != null && reads != null) {

const ratio = reads > 0 ? writes / reads : null;

return ratio == null

? `${tier} impact — ${formatInteger(writes)} ISR write units with no recorded read units in this window.`

: `${tier} impact — ${formatInteger(writes)} ISR write units vs ${formatInteger(reads)} read units in this window (${round2(ratio)} writes per read).`;

}

if (p95 != null && inv != null) {

const multiple = p95 / SLOW_ROUTE_P95_THRESHOLD_MS;

return `${tier} impact — current 95th percentile duration is ${formatInteger(p95)}ms across ${formatInteger(inv)} function invocations in this window (${round1(multiple)}x the ${formatInteger(SLOW_ROUTE_P95_THRESHOLD_MS)}ms slow-route threshold).`;

}

if (coldPct != null) {

return `${tier} impact — current cold-start share is ${coldPct}%; the gate fires above ${COLD_START_THRESHOLD_PCT}%.`;

}

if (rec?.candidateRef?.startsWith('build_minutes_fanout:') || rec?.kind === 'build_minutes_fanout') {

return buildSharePct != null

? `${tier} impact — Build CPU Minutes account for ${buildSharePct}% of observed billed cost in this window.`

: `${tier} impact — Build CPU Minutes exceeded the gate threshold in this window.`;

}

return `${tier} impact — see follow-up metrics for magnitude.`;

}

function cwvIssue(metric, value, threshold, unit) {

if (value == null || value <= threshold) return null;

return { metric, value, threshold, unit };

}

function formatCwvIssue(i) {

const current = i.metric === 'CLS' ? round2(i.value) : Math.round(i.value);

if (i.unit === 'ms') {

return `${i.metric} below ${formatInteger(i.threshold)}ms (current ${formatInteger(current)}ms)`;

}

return `${i.metric} below ${i.threshold}${i.unit} (current ${current}${i.unit})`;

}

function joinEnglish(parts) {

if (parts.length <= 1) return parts[0] ?? '';

if (parts.length === 2) return `${parts[0]} and ${parts[1]}`;

return `${parts.slice(0, -1).join(', ')}, and ${parts.at(-1)}`;

}

function parseSigNumber(s, re) {

const m = re.exec(s);

if (!m) return null;

const n = Number(String(m[1]).replace(/,/g, ''));

return Number.isFinite(n) ? n : null;

}

function round1(n) {

return Math.round(n * 10) / 10;

}

function round2(n) {

return Math.round(n * 100) / 100;

}

function formatInteger(n) {

if (!Number.isFinite(n)) return String(n);

return Math.round(n).toLocaleString('en-US');

}