Math tracker (/trackers/math): Evan Chen's Napkin, chapter by chapter

Schema math (parts, chapters, sections, activity), seeded with all 100 chapters
(Ch 0-94, appendix A-E), 647 sections, PDF pages, exercise counts and approximate
prereqs. Triggers stamp started_at/completed_at and log status/exercise/note/section
changes; math.apply_progress(jsonb) applies the JSON format bots send. Private by
default via MATH_PRIVATE in #lib/math (owner-only prefix + lock in every tracker list).
Overall + per-part progress, current chapter, prereq hints, quick status buttons,
exercises stepper, notes, optional section ticks, activity log, dependency chart.
Deploy preflight checks the math schema (4 tables, 100 chapters).

src/lib/math.ts

@@ -0,0 +1,39 @@
+// Math tracker (/trackers/math): Evan Chen's "An Infinitely Large Napkin". Shared by the
+// server (owner gate, loads) and the page.
+
+/**
+ * The privacy switch. true: owner-only (404 for everyone else, lock icon in every tracker
+ * list). false: a public, read-only page for everyone else (notes stay owner-only, edits
+ * are always owner-only). Flip this one constant; owner.ts and projects.ts read it.
+ */
+export const MATH_PRIVATE = true;
+
+export const MATH_STATUSES = ['not_started', 'reading', 'exercises', 'done', 'skipped'] as const;
+export type MathStatus = (typeof MATH_STATUSES)[number];
+
+export const STATUS_LABEL: Record<MathStatus, string> = {
+	not_started: 'not started',
+	reading: 'reading',
+	exercises: 'exercises',
+	done: 'done',
+	skipped: 'skipped'
+};
+
+/** The free PDF of the book; chapters link to it with #page=N (PDF page numbers). */
+export const NAPKIN_PDF = 'https://venhance.github.io/napkin/Napkin.pdf';
+export const pdfPage = (page: number) => `${NAPKIN_PDF}#page=${page}`;
+
+/** "9,10,11,12,18" → "9–12, 18" (numeric keys only; letters are listed as-is). */
+export function compactKeys(keys: readonly string[]): string {
+	const nums = keys.filter((k) => /^\d+$/.test(k)).map(Number);
+	const other = keys.filter((k) => !/^\d+$/.test(k));
+	nums.sort((a, b) => a - b);
+	const out: string[] = [];
+	for (let i = 0; i < nums.length;) {
+		let j = i;
+		while (j + 1 < nums.length && nums[j + 1] === nums[j] + 1) j++;
+		out.push(j - i >= 2 ? `${nums[i]}–${nums[j]}` : nums.slice(i, j + 1).join(', '));
+		i = j + 1;
+	}
+	return [...out, ...other].join(', ');
+}