"use client"; // The entry list, as wide cards. // // Card height is deliberately variable and nothing reserves space for prose: // only about one entry in five has a `statement` or an `aiRole`, so a fixed // card would render four-fifths of the list as mostly-empty rectangles. A lean // Erdős entry collapses to two compact lines; a marquee entry grows to carry its // statement. The fields that ARE always present (type, who posed it, year, age, // model, verification, notability) carry the visual weight instead. // // Cards have no column headers, so sorting moved into an explicit control. import { useEffect, useMemo, useRef, useState } from "react"; import { useBeforePaint } from "@/lib/before-paint"; import { inferLinkKind, topLinkKinds } from "@/lib/link-kinds"; import { DEFAULT_SETTINGS, NUMERIC_KEYS, PAGE_SIZES, PERIODS, PERIOD_DAYS, SETTINGS_COOKIE, SETTINGS_COOKIE_MAX_AGE, SETTINGS_KEY, SORTS, TIME_SENSITIVE, normalizeListSettings, parseSelection, selectionMatches, sortValue, toggleSelection, type ListSettings, type SortDir, type SortKey, } from "@/lib/list-settings"; import { SOURCE_HOSTS, sourceHostKey } from "@/lib/source-hosts"; import Link from "next/link"; import { ageAtSolve, AI_CONTRIBUTIONS, FIELD_GROUPS, PUBLICATION_STATUSES, RESOLUTION_METHODS, RESOLUTION_STATUSES, type CardEntry, type FieldGroup, type Period, type SolveType, type VerificationStatus, } from "@/lib/problems"; import { entrySourceIds, extractSourceId } from "@/lib/source-ids"; import { AI_CONTRIBUTION, DASH, MODEL_FAMILIES, PUBLICATION, RESOLUTION, RESOLUTION_METHOD, SIGNIFICANCE_HELP, SOLVE_TYPE, VERIFICATION, } from "@/lib/display"; import { FilterPanel, type FilterFacet } from "@/components/FilterPanel"; import { Icon, type IconName } from "@/components/Icons"; import { StatusIcon } from "@/components/StatusIcon"; import { InfoTip, StarNote } from "@/components/Tooltip"; import { VoteButtons } from "@/components/VoteButtons"; import { TeX, deTeX } from "@/components/TeX"; // The clock for period cutoffs, fixed at module load: render purity wants a // stable now, and a cutoff drifting by the age of the tab is nothing against // 7/30-day windows. const LOADED_AT = Date.now(); /// Compact page list: first, last, current and neighbours, with gaps elsewhere. function pageWindow(current: number, total: number): (number | "gap")[] { if (total <= 7) return Array.from({ length: total }, (_, i) => i + 1); const wanted = new Set([1, total, current, current - 1, current + 1]); const nums = [...wanted] .filter((p) => p >= 1 && p <= total) .sort((a, b) => a - b); const out: (number | "gap")[] = []; let prev = 0; for (const p of nums) { if (p - prev > 1) out.push("gap"); out.push(p); prev = p; } return out; } function Chevron({ dir }: { dir: "left" | "right" }) { return ( ); } /// One dot-separated fact in the card's fact line. Deliberately NOT /// whitespace-nowrap: values like a six-model credit line are wider than a /// phone-sized card, so a fact must be able to wrap internally rather than /// overflow the card. function Fact({ label, children, }: { label: string; children: React.ReactNode; }) { return ( {label} {children} ); } /// "8 Aug 2026" from an ISO timestamp. Deliberately not RelativeTime: this /// sits in a dense metadata row where "3 days ago" would need re-reading /// against the solve date next to it, and unlike the feed these dates are /// mostly weeks old, where the absolute form is the more useful one. function formatAddedDate(iso: string): string { const d = new Date(iso); return `${d.getUTCDate()} ${MONTHS_SHORT[d.getUTCMonth()]} ${d.getUTCFullYear()}`; } const MONTHS_SHORT = [ "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec", ]; function ProblemCard({ p, statementHtml, }: { p: CardEntry; statementHtml: string | null; }) { const st = SOLVE_TYPE[p.solveType]; // The primary source counts as a link. For 265 of the entries it IS the // paper, so leaving it out would have shown a paper icon only on the // minority that happen to carry a second copy as an extra link. It has no // stored kind of its own, so it is classified from its URL and name. const linkIcons = topLinkKinds([ { url: p.sourceUrl, label: p.sourceName, kind: inferLinkKind(p.sourceUrl, p.sourceName), }, ...p.links, ]); // The trust badge: verification when it says something; the publication // stage as the fallback when nobody independent has checked yet - // reproducing the old single-ladder look over honest two-axis data. const v = p.verification === "unreviewed" && p.publication ? PUBLICATION[p.publication] : VERIFICATION[p.verification]; const res = RESOLUTION[p.resolution]; const age = ageAtSolve(p); // Result dot + status pill + contribution pill. Rendered twice: beside the // title on desktop, but on a phone the header column stops ~90px short of // the card edge (the vote column reserves its width even below the // buttons), which wrapped the pills after two despite visible space - so // there they render below the header at the true full card width. const badges = ( <> {st.label} {/* A non-default resolution qualifies the headline claim, so it sits right beside it as a small pill. "Resolved" renders nothing - the default state should add no noise. */} {res.pill && ( {res.pill} )} {/* Same convention for the AI-contribution axis; unclassified entries show nothing. */} {p.aiContribution && AI_CONTRIBUTION[p.aiContribution]?.pill && ( {AI_CONTRIBUTION[p.aiContribution].pill} )} ); return ( // The whole card is clickable: the title link's ::after stretches over the // card (so semantics and keyboard focus stay on a real link), and every // interactive child sits above the overlay with `relative z-10`. // Hover/focus feedback lives in globals.css (.entry-card), gated to real // mouse pointers and keyboard focus: on touch devices an emulated :hover // or tap-focus repaint is exactly the "card flashes when I press it" // report under Chrome's auto-dark mode, and a finger on the card needs no // hover affordance anyway.
{/* Only the HEADER shares a row with the votes. Everything below runs the full width of the card - when the votes sat in a full-height flex column they reserved their width all the way down, wrapping statements at ~60% width on a phone for no reason. */}
{/* Title + result */}

{p.name}

{/* Desktop placement: beside the title, as one group. */} {badges}
{/* Votes, kept out of the flowing text so they line up down the list */}
{/* Everything below the header spans the whole card. */}
{/* Mobile placement of the badges: full card width, so all three fit one line on any normal phone. */} {badges} {/* The result qualifier can be a whole sentence, so it lives below the header row where it wraps at the FULL card width instead of squeezing beside the vote buttons. */} {p.resultNote && ( // Clamped: at the 200-character cap this is five lines on a phone, // which on a card buries the identity line under a caveat. The entry // page carries it in full.

({p.resultNote})

)} {/* Identity line */}

{p.problemNumber !== null && <>Erdős #{p.problemNumber} · } {p.field ?? DASH}

{/* Statement, rendered to HTML on the server so no KaTeX runs here. Beyond the first page it arrives via the lazy statements map. */} {statementHtml && (

)} {/* Facts that every entry has */} {/* items-baseline: the ageNote's StarNote is an align-super button, which grows its fact's line box upward - without a shared baseline the flex default let that whole fact sit visibly lower than its neighbours ("Open 11y*" hung below "Posed by" and "Model"). */}

{p.posedBy ?? DASH} {p.yearPosed !== null && `, ${p.yearPosed}`} · {age !== null ? `${age}y` : DASH} {p.ageNote && } · {p.model} {p.modelMaker && ` (${p.modelMaker})`} · {p.solveDate}
{/* Verification + notability + discussion */}
{/* Reserved width so Significance starts at the same x down the list instead of stepping in and out with the badge text. Measured rather than guessed: the widest badge in common use is "Site-confirmed" at 93px, so 6rem reserves 3px of slack. The first attempt used 7.75rem, which aligned correctly but left ~30px of dead gap that read as broken padding. Applied at every width. An earlier version scoped this to `sm` on the theory that the row wraps on a phone; it does not - measured at 360px, nothing wraps to a second line, so the only thing the breakpoint achieved was leaving every screen under 640px ragged. */} {v.label} {/* A documented problem with the claim itself - rare, loud. */} {p.claimIssueNote && ( Claim issue )} {/* AI-estimated problem weight; the Wikipedia count moved to the entry page as a supporting fact (it was almost always 0 here). */} {p.significance !== null && p.significance !== undefined && ( // inline-flex, not a plain span. Its neighbours in this row - // the verification badge and the comment link - are inline-flex // boxes because they carry icons, and a plain inline span sits // 1.83px lower than they do under `items-center`, which centres // boxes rather than text. Measured: matching the box type takes // the skew to exactly 0. It is not a font-metric problem; // forcing both spans to the same font family changes nothing. {/* The metric explanation belongs to the label+value only; the star carries the per-entry justification. Nesting the star under the same title showed BOTH bubbles when hovering it. */} Significance{" "} {p.significance} {p.significanceNote && } )} {/* Straight to the artifact. The question a reader most often has about an entry on this page is "is there a paper" or "is there a Lean proof", and answering it used to mean opening the entry and reading a list of free-text labels. These are the entry's own links, typed, so the icon is a promise about what is on the other end. z-10 lifts them above the card's click overlay. */} {linkIcons.length > 0 && ( {linkIcons.map(({ spec, link }) => ( ))} )} {/* Credit where an entry came from a reader - contributors should see their name on the front page, not only on the entry page. Links to their profile; z-10 lifts it above the card overlay. */} {p.submittedBy && ( // The space is a non-breaking one inside the text, not a `{" "}` // between the label and the link. Flexbox drops a whitespace-only // text node sitting between two flex items, so the words ran // together the moment this span became inline-flex; a trailing // ordinary space would be trimmed at the end of its own flex item // too. `gap-1` would work but at 4px reads tighter than the // natural space in `Fact` label/value pairs on the row above. // The Significance span is unaffected only because its space // lives inside a nested inline span. Submitted by  {p.submittedBy} {/* Only alongside a submitter, never on its own. `addedAt` is row creation, and the curated baseline was seeded within the same few seconds, so on those entries it records when the database was filled rather than anything about the entry. Beside a pseudonym it means what it looks like. */}  on {formatAddedDate(p.addedAt)} )} {p.commentCount > 0 && ( {p.commentCount} {p.commentCount === 1 ? "comment" : "comments"} )}
); } export function ProblemCards({ problems, initial = DEFAULT_SETTINGS, }: { problems: CardEntry[]; /// The view the SERVER already rendered, read from the settings cookie. /// Seeding state from it is the whole point of the cookie: the markup and /// the first client render agree, so there is no reshuffle to watch. initial?: ListSettings; }) { const [query, setQuery] = useState(""); const [fieldFilter, setFieldFilter] = useState(initial.fieldFilter); const [resultFilter, setResultFilter] = useState(initial.resultFilter); const [statusFilter, setStatusFilter] = useState(initial.statusFilter); const [contributionFilter, setContributionFilter] = useState( initial.contributionFilter, ); const [modelFilter, setModelFilter] = useState(initial.modelFilter); const [verificationFilter, setVerificationFilter] = useState( initial.verificationFilter, ); const [publicationFilter, setPublicationFilter] = useState( initial.publicationFilter, ); const [methodFilter, setMethodFilter] = useState(initial.methodFilter); const [sourceFilter, setSourceFilter] = useState(initial.sourceFilter); const [sortKey, setSortKey] = useState(initial.sortKey); const [sortDir, setSortDir] = useState(initial.sortDir); const [period, setPeriod] = useState(initial.period); const [page, setPage] = useState(1); const [perPage, setPerPage] = useState(initial.perPage); // Field chips: every group that actually occurs, with its count, BIGGEST // FIRST. Fixed taxonomy order put one-entry groups ahead of hundred-entry // ones, so the chips a reader is most likely to want were the ones they had // to hunt for. Ties fall back to taxonomy order to keep the row stable // rather than reshuffling on every entry added. const groups = useMemo(() => { const counts = new Map(); for (const p of problems) { if (p.fieldGroup) counts.set(p.fieldGroup, (counts.get(p.fieldGroup) ?? 0) + 1); } return FIELD_GROUPS.filter((g) => counts.has(g)) .map((g) => ({ group: g, count: counts.get(g)! })) .sort((a, b) => b.count - a.count); }, [problems]); // Same present-values trick for resolution statuses. While every entry is // "resolved" (the state of the dataset today) the whole control stays // hidden; it appears by itself the day a candidate or retraction lands. const resolutions = useMemo(() => { const present = new Set(problems.map((p) => p.resolution)); return RESOLUTION_STATUSES.filter((r) => present.has(r)); }, [problems]); // AI-contribution tiers that occur. Unlike the status control, this one // appears as soon as a SINGLE classified entry exists: with most of the // catalog unclassified (null), filtering on one tier is not a no-op. const contributions = useMemo(() => { const present = new Set( problems.map((p) => p.aiContribution).filter(Boolean), ); return AI_CONTRIBUTIONS.filter((c) => present.has(c)); }, [problems]); // Restore the persisted settings once, after hydration - localStorage is // client-only, so reading it during the first render would make server and // client HTML disagree (the setState-in-effect lint rule is disabled for // exactly that reason: this IS the sanctioned use, syncing state in from an // external system that only exists on the client). Every value is validated // against what the UI can actually offer today, so a stale or tampered // entry falls back silently. // // Before paint, not after. As an ordinary effect the list rendered in the // default order and then visibly reshuffled into the remembered one, which // on a 400-entry list is the most conspicuous flicker on the site. const [restored, setRestored] = useState(false); // URL mirroring happens only after an explicit interaction with a control. // A "first persist run" heuristic breaks under StrictMode's double effects // (the second run wrote remembered settings into a freshly loaded URL); // this flag is set in the handlers themselves, so it cannot misfire. const touched = useRef(false); const touch = () => { touched.current = true; }; useBeforePaint(() => { // Two sources on top of what the server already used, in order of // authority: the cookie the page rendered from, then this browser's // localStorage, then the URL. A shared link beats a remembered view; a // remembered view beats a cookie that may lag behind another tab. // // With the cookie in place this usually resolves to exactly the state // already rendered, React bails out of the update, and nothing moves. let stored: unknown = {}; try { stored = JSON.parse(localStorage.getItem(SETTINGS_KEY) ?? "null") ?? {}; } catch { // Malformed storage reads as "nothing stored". } const url = new URLSearchParams(window.location.search); const fromUrl: Record = {}; const PARAMS: [string, keyof ListSettings][] = [ ["field", "fieldFilter"], ["result", "resultFilter"], ["status", "statusFilter"], ["contribution", "contributionFilter"], ["model", "modelFilter"], ["verification", "verificationFilter"], ["publication", "publicationFilter"], ["method", "methodFilter"], ["source", "sourceFilter"], ["sort", "sortKey"], ["dir", "sortDir"], ["period", "period"], ]; for (const [param, key] of PARAMS) { const v = url.get(param); if (v !== null) fromUrl[key] = v; } const per = url.get("per"); if (per !== null) fromUrl.perPage = Number(per); const next = normalizeListSettings({ ...initial, ...(typeof stored === "object" && stored !== null ? stored : {}), ...fromUrl, }); setFieldFilter(next.fieldFilter); setResultFilter(next.resultFilter); setStatusFilter(next.statusFilter); setContributionFilter(next.contributionFilter); setModelFilter(next.modelFilter); setVerificationFilter(next.verificationFilter); setPublicationFilter(next.publicationFilter); setMethodFilter(next.methodFilter); setSourceFilter(next.sourceFilter); setSortKey(next.sortKey); setSortDir(next.sortDir); setPeriod(next.period); setPerPage(next.perPage); setRestored(true); // Once per mount on purpose so it cannot undo choices made since. }, []); // Persist on every change - but only after restore has run, otherwise the // first render would overwrite the stored settings with the defaults. useEffect(() => { if (!restored) return; const s: ListSettings = { fieldFilter, resultFilter, statusFilter, contributionFilter, modelFilter, verificationFilter, publicationFilter, methodFilter, sourceFilter, sortKey, sortDir, period, perPage, }; const json = JSON.stringify(s); try { localStorage.setItem(SETTINGS_KEY, json); } catch { // Storage full or blocked - the list still works, it just won't persist. } // The same thing again where the SERVER can see it. This copy is what // lets the next page load render in this order rather than the default // one, and it is the only reason a cookie is involved at all. Lax so it // rides ordinary navigation without being sent on cross-site requests; // no sensitive content, so nothing here needs more than that. // // Only when it says something. A reader on the defaults gets no cookie at // all rather than one asserting the defaults, and going back to them // removes it again - so the common visitor keeps a bare request and the // server keeps serving them the same default order it always did. const isDefault = ( Object.keys(DEFAULT_SETTINGS) as (keyof ListSettings)[] ).every((k) => s[k] === DEFAULT_SETTINGS[k]); try { document.cookie = isDefault ? `${SETTINGS_COOKIE}=; path=/; max-age=0; samesite=lax` : `${SETTINGS_COOKIE}=${encodeURIComponent(json)}; path=/; max-age=${SETTINGS_COOKIE_MAX_AGE}; samesite=lax`; } catch { // Cookies disabled: the list still works, the server just keeps // rendering the default order and the client corrects it as before. } // Mirror non-default settings into the URL so a filtered view is // shareable - but only once the VISITOR changes something. Loading or // navigating to the page must leave the address bare (and a shared // link's params untouched). if (!touched.current) return; const q = new URLSearchParams(); if (fieldFilter !== "all") q.set("field", fieldFilter); if (resultFilter !== "all") q.set("result", resultFilter); if (statusFilter !== "all") q.set("status", statusFilter); if (contributionFilter !== "all") q.set("contribution", contributionFilter); if (modelFilter !== "all") q.set("model", modelFilter); if (verificationFilter !== "all") q.set("verification", verificationFilter); if (publicationFilter !== "all") q.set("publication", publicationFilter); if (methodFilter !== "all") q.set("method", methodFilter); if (sourceFilter !== "all") q.set("source", sourceFilter); if (sortKey !== "solveDate") q.set("sort", sortKey); if (sortDir !== "desc") q.set("dir", sortDir); if (period !== "all") q.set("period", period); if (perPage !== 25) q.set("per", String(perPage)); // URLSearchParams percent-encodes the comma that separates a facet's // options, turning a shared link into ?contribution=a%2Cb. A comma is a // legal sub-delimiter in a query string and `url.get` reads it back // identically, so it is put back purely so the address bar stays legible. // Safe to do blindly: no option value contains a comma of its own. const qs = q.toString().replace(/%2C/g, ","); window.history.replaceState( null, "", qs ? `?${qs}` : window.location.pathname, ); }, [ restored, fieldFilter, resultFilter, statusFilter, contributionFilter, modelFilter, verificationFilter, publicationFilter, methodFilter, sourceFilter, sortKey, sortDir, period, perPage, ]); // Statements beyond the first default-sort page ship without their rendered // HTML; one background fetch fills the map after hydration (see CardEntry). const [lateStatements, setLateStatements] = useState | null>(null); useEffect(() => { if (!problems.some((p) => p.hasStatement && p.statementHtml === null)) return; let alive = true; fetch("/api/statements") .then((r) => r.ok ? (r.json() as Promise>) : null, ) .then((map) => { if (alive && map) setLateStatements(map); }) .catch(() => { // First-page statements are inline regardless; deeper cards just // render without prose until a retry on next navigation. }); return () => { alive = false; }; }, [problems]); // Only offer verification statuses that actually occur, in ladder order, so // the panel never lists an empty category. const verifications = useMemo(() => { const present = new Set(problems.map((p) => p.verification)); return (Object.keys(VERIFICATION) as VerificationStatus[]).filter((v) => present.has(v), ); }, [problems]); // The facet groups the Filters panel offers. Same visibility rules the old // dropdown row used: status hides while the dataset is uniform, // contribution appears with the first classified entry. const facets: FilterFacet[] = [ { key: "result", label: "Result", options: (Object.keys(SOLVE_TYPE) as SolveType[]).map((t) => ({ value: t, label: SOLVE_TYPE[t].label, })), }, ...(resolutions.length > 1 ? [ { key: "status", label: "Status", options: resolutions.map((r) => ({ value: r, label: RESOLUTION[r].label, })), }, ] : []), ...(contributions.length > 0 ? [ { key: "contribution", label: "AI contribution", options: contributions.map((c) => ({ value: c, label: AI_CONTRIBUTION[c].label, })), }, ] : []), { // Same family buckets as the stats chart; a multi-system entry matches // every family named on it. key: "model", label: "AI system", options: MODEL_FAMILIES.filter((f) => problems.some((p) => f.test.test(p.model)), ).map((f) => ({ value: f.key, label: f.label })), }, { key: "verification", label: "Verification", options: verifications.map((v) => ({ value: v, label: VERIFICATION[v].label, })), }, { key: "publication", label: "Publication", options: PUBLICATION_STATUSES.filter((v) => problems.some((p) => p.publication === v), ).map((v) => ({ value: v, label: PUBLICATION[v].label })), }, { // WHERE the source lives, as distinct from what kind of thing it is // (the publication facet above). Only the buckets present today. key: "source", label: "Source", options: SOURCE_HOSTS.filter((h) => problems.some((p) => sourceHostKey(p.sourceUrl) === h.key), ).map((h) => ({ value: h.key, label: h.label })), }, ...(problems.some((p) => p.resolutionMethod) ? [ { key: "method", label: "Method", options: RESOLUTION_METHODS.filter((v) => problems.some((p) => p.resolutionMethod === v), ).map((v) => ({ value: v, label: RESOLUTION_METHOD[v].label })), }, ] : []), ]; const filterValues: Record = { result: resultFilter, status: statusFilter, contribution: contributionFilter, model: modelFilter, verification: verificationFilter, publication: publicationFilter, method: methodFilter, source: sourceFilter, }; // Takes the whole new value rather than one option: the panel and the chip // row both compute it with toggleSelection, and Clear passes "all". function setFilter(key: string, value: string) { touch(); if (key === "result") setResultFilter(value); else if (key === "status") setStatusFilter(value); else if (key === "contribution") setContributionFilter(value); else if (key === "model") setModelFilter(value); else if (key === "verification") setVerificationFilter(value); else if (key === "publication") setPublicationFilter(value); else if (key === "method") setMethodFilter(value); else if (key === "source") setSourceFilter(value); } const filtered = useMemo(() => { const q = query.trim().toLowerCase(); // Computed once for the whole pass rather than per entry: parsing a URL // 600 times per keystroke is the kind of thing that makes a search box // feel slow. const queryId = extractSourceId(query); // Rolling cutoff, matching the engagement metrics' windows. Only // non-engagement sorts date-filter; score/discussion window their metric // in sortValue instead, ranking the WHOLE list by that period's activity. const dateFiltering = period !== "all" && !TIME_SENSITIVE.includes(sortKey); const cutoff = dateFiltering ? new Date( LOADED_AT - PERIOD_DAYS[period as Exclude] * 86400000, ) .toISOString() .slice(0, 10) : ""; // Resolved to regexes once, for the same reason as queryId: the model // facet is the one filter that cannot compare values directly, and // scanning MODEL_FAMILIES per entry per keystroke is work with no payoff. const chosenModels = parseSelection(modelFilter); const modelTests = MODEL_FAMILIES.filter((f) => chosenModels.includes(f.key), ).map((f) => f.test); return problems.filter((p) => { if (dateFiltering) { // "Added" scopes by when the entry entered the catalog; every other // sort scopes by when the problem was solved. Imprecise solve dates // ("2026-07") compare lexically and sit out of week-sized windows, // which is the honest reading of a date that vague. const stamp = sortKey === "added" ? p.addedAt.slice(0, 10) : sortKey === "changed" ? p.changedAt.slice(0, 10) : p.solveDate; if (stamp < cutoff) return false; } // Options within a facet are alternatives, facets AND with each other - // see selectionMatches. An empty facet passes everything, so this reads // the same as the single-value version it replaced. if (!selectionMatches(fieldFilter, p.fieldGroup)) return false; if (!selectionMatches(resultFilter, p.solveType)) return false; if (!selectionMatches(statusFilter, p.resolution)) return false; if (!selectionMatches(contributionFilter, p.aiContribution)) return false; // The one facet matched by pattern rather than by value: an entry names // its systems in free text, and a multi-system entry belongs to every // family named on it. if (modelTests.length > 0 && !modelTests.some((t) => t.test(p.model))) return false; if (!selectionMatches(verificationFilter, p.verification)) return false; if (!selectionMatches(publicationFilter, p.publication)) return false; if (!selectionMatches(methodFilter, p.resolutionMethod)) return false; // Derived from the URL rather than stored, so it cannot drift from // the source it describes. Cheap: one URL parse per entry per pass. if (!selectionMatches(sourceFilter, sourceHostKey(p.sourceUrl))) return false; if (!q) return true; // A pasted link or a bare arXiv id is an identity, not a word: compare // it against what the entry's links actually point at, so // arxiv.org/pdf/2608.13637v2 finds an entry filed under /abs/ and a // Zenodo DOI finds one filed under the record URL. Returns early // because a match here is exact and needs no text scoring. if (queryId && entrySourceIds(p.sourceUrl, p.links).includes(queryId)) return true; const haystack = [ // Both forms: a name carrying math is displayed rendered, so someone // searching types what they see ("Lp(L1)"), not the source ("$L_p(L_1)$"). p.name, deTeX(p.name), p.field, p.fieldGroup, p.posedBy, p.model, p.submittedBy, ...p.humanCollaborators, ] .filter(Boolean) .join(" ") .toLowerCase(); return haystack.includes(q); }); }, [ problems, query, period, sortKey, fieldFilter, resultFilter, statusFilter, contributionFilter, modelFilter, verificationFilter, publicationFilter, methodFilter, sourceFilter, ]); const sorted = useMemo(() => { const arr = [...filtered]; arr.sort((a, b) => { const va = sortValue(a, sortKey, period); const vb = sortValue(b, sortKey, period); const cmp = typeof va === "number" && typeof vb === "number" ? va - vb : String(va).localeCompare(String(vb)); // Ties on an engagement sort fall back to most recently solved, so an // all-zero week does not render in arbitrary order. if (cmp === 0 && TIME_SENSITIVE.includes(sortKey)) { return b.solveDate.localeCompare(a.solveDate); } return sortDir === "asc" ? cmp : -cmp; }); return arr; }, [filtered, sortKey, sortDir, period]); // Reset to the first page whenever the result set, ordering or page size // changes. Adjusted during render rather than in an effect (which would cause // a cascading render, and which the react-hooks lint rule rejects). Keeping it // centralised on a signature also means a new filter cannot forget to do it. const signature = [ query, fieldFilter, resultFilter, statusFilter, contributionFilter, modelFilter, verificationFilter, publicationFilter, methodFilter, sourceFilter, perPage, sortKey, sortDir, period, ].join("|"); const [lastSignature, setLastSignature] = useState(signature); if (signature !== lastSignature) { setLastSignature(signature); setPage(1); } const totalPages = Math.max(1, Math.ceil(sorted.length / perPage)); const current = Math.min(page, totalPages); const start = (current - 1) * perPage; const paged = sorted.slice(start, start + perPage); // Controls sit directly on the page surface, so they use the raised surface // to read as controls rather than melting into the paper. Every control in // both rows is h-9 so the search box, the filters and the sort controls line // up as one system - their differing font sizes used to give them differing // heights. // Rounding is NOT in the base, so the one select that bonds to a neighbour // can square that edge by choosing its own corners. Overriding `rounded` // with `rounded-r-none` would work only as long as Tailwind keeps emitting // the corner utilities after the shorthand, which is not a guarantee worth // depending on for a visible seam. const selectBase = "h-9 min-w-0 max-w-[45vw] sm:max-w-[12rem] border border-[var(--hairline)] bg-[var(--paper-raised)] px-2 text-xs text-[var(--ink-secondary)] transition-colors hover:border-[var(--ink-muted)] focus:outline-none focus:ring-1 focus:ring-[var(--accent-blue)]"; const selectClass = `${selectBase} rounded`; const pageBtn = "inline-flex h-9 min-w-9 items-center justify-center rounded-md border border-[var(--hairline)] bg-[var(--paper-raised)] px-2.5 text-sm text-[var(--ink-secondary)] transition-colors hover:border-[var(--ink-muted)] hover:text-[var(--ink)] disabled:pointer-events-none disabled:opacity-40"; const chosenFields = parseSelection(fieldFilter); const filtersActive = query || fieldFilter !== "all" || resultFilter !== "all" || statusFilter !== "all" || contributionFilter !== "all" || modelFilter !== "all" || verificationFilter !== "all" || publicationFilter !== "all" || methodFilter !== "all" || sourceFilter !== "all"; // `grow justify-center sm:grow-0`: on a phone the wrapped chip rows // stretch to fill the full width instead of leaving a ragged right edge; // on wider screens they keep their natural size. const chip = (active: boolean) => `inline-flex grow items-center justify-center gap-1.5 whitespace-nowrap rounded-full border px-2.5 py-1 text-xs transition-colors sm:grow-0 ${ active ? "border-[var(--accent-blue)] bg-[color-mix(in_srgb,var(--accent-blue)_10%,transparent)] font-medium text-[var(--accent-blue)]" : "border-[var(--hairline)] bg-[var(--paper-raised)] text-[var(--ink-secondary)] hover:border-[var(--ink-muted)] hover:text-[var(--ink)]" }`; return (
{/* Field taxonomy chips, with counts. One row that wraps; groups with no entries never render. Chips accumulate like every other facet - Algebra plus Analysis shows both - and "All fields" is how you get back to none. */}
{groups.map(({ group, count }) => ( ))}
{/* Search + filters */}
setQuery(e.target.value)} placeholder="Search name, field, model, people…" className="h-9 w-full rounded border border-[var(--hairline)] bg-[var(--paper-raised)] pl-8 pr-3 text-sm text-[var(--ink)] transition-colors placeholder:text-[var(--ink-muted)] hover:border-[var(--ink-muted)] focus:outline-none focus:ring-1 focus:ring-[var(--accent-blue)]" />
{/* Active facets stay visible as removable chips while the panel is closed, on their own row under the search box, with Clear at the end. The row only exists while something is filtered. */} {filtersActive && (
{/* One chip per CONDITION, not per facet: two options chosen in the same facet are two independent things to see and to remove, and a single chip could only offer to drop both. */} {facets.flatMap((f) => parseSelection(filterValues[f.key]).map((v) => { const label = f.options.find((o) => o.value === v)?.label ?? v; return ( ); }), )} {/* A pill, like the chips it sits beside, but deliberately not a blue one: the chips are blue because each is an active filter, and a blue "Clear all" would read as one more of them rather than the thing that removes them. Neutral until hovered, then orange, which is the site's colour for an undoing action. */}
)} {/* Sort - explicit, because cards have no column headers to click. Each label plus its control is ONE flex item, so a wrap can never land between them. The flat row this replaced put six siblings in a wrapping flex, which on a phone broke after "Period" and left that label stranded at the end of the line above its own dropdown. */}
{/* Sort key and direction are one decision, so they are one bonded control: the select and the toggle share an edge (-ml-px collapses the doubled border) and read as a unit rather than as two unrelated dropdowns. */}
{/* Belongs to the SORT control, not to Period: it explains what the significance scale means. It used to render after the period dropdown, where it looked like Period's footnote. */} {sortKey === "significance" && ( )}
{/* Period applies to every sort: it windows the metric on the engagement sorts and date-filters the list on the rest (see TIME_SENSITIVE). All time is the default. A select rather than a segmented control: five rolling windows in pills would wrap onto its own row on phones, and the dropdown leaves room to add windows later without spending width. */}
{/* The live result count: reads "all N entries" untouched, and "showing X of N entries" the moment a filter or search bites. Full width on phones so it takes its own line instead of competing with the controls. Left to wrap on its own rather than forced to a full-width line: on a phone it fits beside Period, and forcing the break would spend a whole row to say one short sentence. */} {sorted.length === problems.length ? ( <>all {problems.length} entries ) : ( <> showing{" "} {sorted.length} {" "} of {problems.length} entries )}
{/* Cards */} {paged.length === 0 ? (

No entries match those filters.

) : (
{paged.map((p) => ( ))}
)} {/* Pagination */}
{pageWindow(current, totalPages).map((p, i) => p === "gap" ? ( … ) : ( ), )}
); }