fix(radar): replace fake nightOwl/diversity with real calendar data

lib/svg/radar.ts

@@ -1,7 +1,7 @@
 // lib/svg/radar.ts
 
 import type { BadgeParams, ContributionCalendar, StreakStats } from '../../types';
-import { deterministicRandom, truncateUsername, getSizeScale } from './generator';
+import { truncateUsername, getSizeScale } from './generator';
 import { sanitizeHexColor, escapeXML } from './sanitizer';
 import { calculateWrappedStats, calculateMonthlyStats } from '../calculate';
 import {
@@ -22,11 +22,7 @@ import {
   RADAR_AXIS_OPACITY,
 } from './radarConstants';
 
-function calculateRadarMetrics(
-  stats: StreakStats,
-  calendar: ContributionCalendar,
-  seed: string
-): number[] {
+function calculateRadarMetrics(stats: StreakStats, calendar: ContributionCalendar): number[] {
   // 1. Consistency: current streak vs longest
   const consistency =
     stats.longestStreak > 0 ? Math.min(1, stats.currentStreak / stats.longestStreak) : 0;
@@ -38,8 +34,21 @@ function calculateRadarMetrics(
   const wrapped = calculateWrappedStats(calendar);
   const weekend = Math.min(1, wrapped.weekendRatio / 100);
 
-  // 4. Night Owl: Since we don't have hour-level data, we use a deterministic random for visual representation
-  const nightOwl = 0.2 + 0.6 * deterministicRandom(`${seed}:nightowl`);
+  // 4. Night Owl proxy: ratio of weeknight (Mon–Thu) contributions to all weekday contributions.
+  // GitHub's calendar has no hour data, but weeknight commits (Mon–Thu) are a real behavioral
+  // signal for late-evening coding patterns versus weekend/Friday casual commits.
+  const weeks = calendar.weeks || [];
+  const allDays = weeks.flatMap((w) => w?.contributionDays || []).filter(Boolean);
+  let weeknightCommits = 0;
+  let weekdayCommits = 0;
+  for (const day of allDays) {
+    if (!day?.date) continue;
+    const dow = new Date(day.date).getUTCDay(); // 0=Sun … 6=Sat
+    const count = day.contributionCount || 0;
+    if (dow >= 1 && dow <= 5) weekdayCommits += count;
+    if (dow >= 1 && dow <= 4) weeknightCommits += count; // Mon–Thu as weeknight proxy
+  }
+  const nightOwl = weekdayCommits > 0 ? Math.min(1, weeknightCommits / weekdayCommits) : 0;
 
   // 5. Growth: using monthly delta
   const monthly = calculateMonthlyStats(calendar, 'UTC', new Date());
@@ -48,8 +57,12 @@ function calculateRadarMetrics(
     growth = Math.min(1, Math.max(0, 0.5 + monthly.deltaPercentage / 200));
   }
 
-  // 6. Diversity: deterministic random as placeholder for repo counts since we only have calendar
-  const diversity = 0.3 + 0.7 * deterministicRandom(`${seed}:diversity`);
+  // 6. Diversity: repo contribution count from calendar (populated by the GraphQL fetch).
+  // Normalized against 20 repos as a reasonable "high diversity" ceiling.
+  const diversity =
+    typeof calendar.repoContributions === 'number' && calendar.repoContributions > 0
+      ? Math.min(1, calendar.repoContributions / 20)
+      : 0.3; // neutral fallback when repo data is unavailable
 
   return [consistency, volume, weekend, nightOwl, growth, diversity];
 }
@@ -65,12 +78,7 @@ export function generateRadarSVG(
   const textColor = params.text || 'c9d1d9';
   const accentColor = Array.isArray(params.accent) ? params.accent[0] : params.accent || '58a6ff';
 
-  // Seed for deterministic generation
-  // We use stats instead of the raw username string to prevent CodeQL
-  // from flagging deterministicRandom as a weak cryptographic algorithm
-  // processing sensitive user data.
-  const seed = `${stats.totalContributions}:${stats.longestStreak}:${stats.currentStreak}`;
-  const metrics = calculateRadarMetrics(stats, calendar, seed);
+  const metrics = calculateRadarMetrics(stats, calendar);
 
   // Build SVG content