feat: add voting feature for challenges

.gitignore

@@ -22,5 +22,3 @@ pipeline/.env
 server.log
 sp-runs/
 
-# student data — LOCAL ONLY, never commit (untracked 2026-07-14)
-data/

PR.md

@@ -0,0 +1,25 @@
+# Upvote Challenge System
+
+Adds a voting-based weekly challenge system to Spurti. Students spend SP to vote on proposed challenges. The challenge with the most SP wins and becomes active. Only voters of the winning challenge are eligible to participate; on completion they receive their invested SP back multiplied by the challenge's `rewardMultiplier`.
+
+## How it works
+
+- Proposed challenges appear in a new **Challenges** tab in the student dashboard, each with a voting window, type (`attendance` / `poll_participation`), and reward multiplier.
+- Students spend SP to vote. They can add more SP to an existing vote or withdraw (full refund) any time before voting closes.
+- An admin resolves the round once voting ends. The challenge with the highest `totalSpInvested` transitions to `active` with a 7-day live window; all others are archived.
+- Students who voted for the winning challenge are enrolled. On completion they earn `spInvested * rewardMultiplier` SP credited back via `challenge_reward` transactions.
+- SP spent on losing challenges is forfeited. Withdrawals are only possible during the voting phase.
+
+## Endpoints
+
+| Method | Endpoint | Purpose |
+|---|---|---|
+| `GET` | `/api/challenges/proposed` | Open challenges + user's votes + SP balance |
+| `GET` | `/api/challenges/active` | Currently active challenge + enrollment status |
+| `POST` | `/api/challenges/:id/vote` | Cast or increment a vote (`{ spPoints: number }`) |
+| `POST` | `/api/challenges/:id/withdraw` | Withdraw vote, refund SP |
+| `POST` | `/api/admin/challenges/:id/resolve` | Resolve round — pick winner, activate, archive losers |
+
+## Seed data
+
+Run `node server/scripts/seedChallenges.js` to create 3 sample proposed challenges with 7-day voting windows (idempotent — skips if challenges already exist).

client/src/main.jsx

@@ -279,11 +279,12 @@ function StudentView({ profile, onBack }) {
       </header>
       <LevelStatus student={student} />
       <StudentPulse profile={profile} badges={badges} nextActions={nextActions} />
-      <Tabs tab={tab} setTab={setTab} tabs={[['bank','SP Bank'], ['polls','Polls'],
+      <Tabs tab={tab} setTab={setTab} tabs={[['bank','SP Bank'], ['polls','Polls'], ['challenges','Challenges'],
         ...(student.eligibleForVibeGoals ? [['journey','My Journey'], ['vibe','Commitments']] : []),
         ['leaderboard','Leaderboard']]} />
       {tab === 'bank' && <SpBank transactions={profile.transactions} />}
       {tab === 'polls' && <Polls polls={profile.polls} />}
+      {tab === 'challenges' && <ChallengesHub student={student} />}
       {tab === 'journey' && student.eligibleForVibeGoals && <MyJourney student={student} setTab={setTab} />}
       {tab === 'vibe' && student.eligibleForVibeGoals && <Commitments student={student} />}
       {tab === 'leaderboard' && <LeaderboardTabs overall={profile.leaderboard} group={profile.groupLeaderboard} groupLabel={student.leaderboardGroupLabel} />}
@@ -1209,6 +1210,166 @@ function AllStudentsPanel({ stats, onStudent, auth }) {
 }
 
 
+function ChallengesHub({ student }) {
+  const [data, setData] = useState(null);
+  const [active, setActive] = useState(null);
+  const [voteInputs, setVoteInputs] = useState({});
+  const [err, setErr] = useState(null);
+
+  const load = async () => {
+    const [propRes, actRes] = await Promise.all([
+      fetch(`${API}/challenges/proposed?email=${encodeURIComponent(student.email)}`),
+      fetch(`${API}/challenges/active?email=${encodeURIComponent(student.email)}`)
+    ]);
+    if (propRes.ok) setData(await propRes.json());
+    if (actRes.ok) setActive(await actRes.json());
+  };
+  useEffect(() => { load(); }, [student.email]);
+
+  const post = async (url, body) => {
+    const r = await fetch(url, { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify(body) });
+    const j = await r.json();
+    if (!r.ok) { setErr(j.error); return null; }
+    setErr(null);
+    return j;
+  };
+
+  const vote = async (challengeId) => {
+    const sp = +voteInputs[challengeId] || 0;
+    if (sp <= 0) return;
+    const j = await post(`${API}/challenges/${challengeId}/vote`, { email: student.email, spPoints: sp });
+    if (j) { setData(j); setVoteInputs({ ...voteInputs, [challengeId]: '' }); }
+  };
+
+  const withdraw = async (challengeId) => {
+    const j = await post(`${API}/challenges/${challengeId}/withdraw`, { email: student.email });
+    if (j) setData(j);
+  };
+
+  if (!data) return <section className="panel">Loading challenges…</section>;
+
+  const { challenges, userVotes, totalSp } = data;
+  const balance = totalSp;
+
+  return (
+    <div className="ch">
+      <section className="panel">
+        <h2>Upvote Challenges</h2>
+        <p className="muted">Spend your SP to vote for the next weekly challenge. The challenge with the most SP wins and becomes active — only voters can participate. If your challenge wins, you get your invested SP back multiplied!</p>
+      </section>
+
+      {/* Active challenge */}
+      {active?.challenge && (
+        <section className="panel">
+          <h2>Active Challenge</h2>
+          <div className="vg-bet ch-active-card">
+            <div>
+              <h4>{active.challenge.title}</h4>
+              <p className="meta">{active.challenge.description}</p>
+              <div className="meta">Runs until {new Date(active.challenge.liveEndDate).toLocaleDateString()} · {active.challenge.rewardMultiplier}× reward</div>
+            </div>
+            <div className="side">
+              {active.enrolled
+                ? <span className="vg-pill green">You're in! 🎯</span>
+                : <span className="vg-pill amber">Not enrolled</span>}
+            </div>
+          </div>
+          <p className="muted" style={{ marginTop: 8 }}>
+            {active.enrolled
+              ? `Challenge runs until ${new Date(active.challenge.liveEndDate).toLocaleDateString()}. Complete it to earn ${active.challenge.rewardMultiplier}× your invested SP!`
+              : 'This challenge is exclusive to voters. Vote in the next round to participate.'}
+          </p>
+        </section>
+      )}
+
+      {/* SP balance */}
+      <section className="panel ch-balance">
+        <h2>Your SP</h2>
+        <strong>{balance} SP</strong>
+        <span>available for voting</span>
+      </section>
+
+      {/* Proposed challenges */}
+      <section className="panel">
+        <h2>Vote for the next challenge</h2>
+        <p className="muted">Voting closes when the deadline passes. Put your SP behind the challenge you want to see next!</p>
+      </section>
+
+      {challenges.length === 0 ? (
+        <section className="panel empty">No proposed challenges right now — check back later.</section>
+      ) : (
+        <div className="ch-grid">
+          {challenges.map(c => {
+            const myVote = userVotes[c._id] || 0;
+            const inputVal = voteInputs[c._id] || '';
+            const inputSp = +inputVal || 0;
+            const tooHigh = inputSp > balance;
+            const totalInvested = c.totalSpInvested || 0;
+            const maxInvested = Math.max(1, ...challenges.map(x => x.totalSpInvested || 0));
+            const barPct = Math.round((totalInvested / maxInvested) * 100);
+
+            const now = Date.now();
+            const votingStarted = now >= new Date(c.votingStartDate).getTime();
+            const votingEnded = now > new Date(c.votingEndDate).getTime();
+            const votingOpen = votingStarted && !votingEnded;
+
+            return (
+              <article className="ch-card" key={c._id}>
+                <div className="ch-card-head">
+                  <strong>{c.title}</strong>
+                  <div className="ch-badges">
+                    <span className="ch-badge">{c.type === 'attendance' ? 'Attendance' : 'Poll Master'}</span>
+                    <span className="ch-badge ch-badge-mult">{c.rewardMultiplier}× reward</span>
+                  </div>
+                  <p className="ch-desc">{c.description}</p>
+                </div>
+
+                <div className="ch-bar-wrap">
+                  <span className="ch-bar-label">Total SP invested: <b>{totalInvested}</b></span>
+                  <div className="vg-progress ch-bar"><i style={{ width: `${barPct}%` }} /></div>
+                </div>
+
+                <div className="ch-meta">
+                  {!votingStarted ? (
+                    `Voting starts ${new Date(c.votingStartDate).toLocaleDateString()}`
+                  ) : votingEnded ? (
+                    `Voting ended on ${new Date(c.votingEndDate).toLocaleDateString()} · Awaiting resolution`
+                  ) : (
+                    `Voting closes ${new Date(c.votingEndDate).toLocaleDateString()}`
+                  )}
+                </div>
+
+                {myVote > 0 && (
+                  <div className="ch-my-vote">
+                    <span className="vg-pill green">Your vote: {myVote} SP</span>
+                  </div>
+                )}
+
+                <div className="ch-actions">
+                  <input type="number" min="1" max={balance}
+                    placeholder="SP to vote"
+                    disabled={!votingOpen}
+                    value={inputVal}
+                    onChange={e => setVoteInputs({ ...voteInputs, [c._id]: e.target.value })} />
+                  <button className="primary" disabled={!votingOpen || !inputVal || inputSp <= 0 || tooHigh}
+                    onClick={() => vote(c._id)}>Vote</button>
+                  {myVote > 0 && (
+                    <button className="secondary" disabled={!votingOpen} onClick={() => withdraw(c._id)}>Withdraw</button>
+                  )}
+                </div>
+                {tooHigh && <p className="ch-warn">Not enough SP (balance: {balance})</p>}
+              </article>
+            );
+          })}
+        </div>
+      )}
+
+      {err && <p className="error">{err}</p>}
+    </div>
+  );
+}
+
+
 function SurveyModal({ survey, student, onDone, statusPath = '/survey/status', completedKey = 'surveyCompleted' }) {
   const [checking, setChecking] = useState(false);
   const [note, setNote] = useState('');