update readme

Responsive single-column layout (max 480px) with styles for:
- Option items with label/vote-button rows
- Voted state highlighting (green tint)
- Active/closed timer color states
- Disabled button opacity
- Full-width copy URL button

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitignore

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+node_modules/

README.md

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 # P2P Poll App
+
+A peer-to-peer polling app built with [Automerge](https://automerge.org/) and Vanilla JS. No backend required — polls sync in real time across browsers using CRDTs and a WebSocket relay.
+
+## Features
+
+- **Add options** — type an option and press Enter or click "Add Option". Duplicate options (case-insensitive) are rejected with an inline error message.
+- **Vote on options** — click the vote button next to any option. You can vote on multiple options, but only once per option.
+- **Toggle votes** — click your vote again to remove it (the button turns green with a checkmark when you've voted).
+- **Live vote counts** — options are sorted by vote count in descending order and update in real time as votes come in from other users.
+- **2-minute countdown timer** — click "Start 2-min Vote" to begin a shared countdown. Voting is open before and during the countdown. Once the timer expires, all vote buttons are disabled.
+- **Shared timer** — the deadline is stored in the Automerge document, so all peers see the same countdown and voting closes simultaneously for everyone.
+- **Copy URL** — click "Copy URL" to copy the poll link to your clipboard. Share it with others to join the same poll.
+- **P2P sync** — all state (options, votes, timer) syncs across browsers in real time with no central server handling your data.
+
+## How it works
+
+### Tech stack
+
+- **[Automerge](https://automerge.org/)** via `@automerge/vanillajs` — a CRDT library that lets multiple clients concurrently edit shared documents and merge changes without conflicts.
+- **BroadcastChannelNetworkAdapter** — syncs between tabs in the same browser instantly via the browser's BroadcastChannel API.
+- **WebSocketClientAdapter** — syncs across different browsers/devices via a WebSocket relay (`wss://sync.automerge.org`). The relay only forwards CRDT messages; it does not store or interpret your data.
+- **IndexedDBStorageAdapter** — persists the document locally so it survives page refreshes.
+- **Vite** — bundles the app with WebAssembly support (required by Automerge).
+
+### Data model
+
+The poll is a single Automerge document with three fields:
+
+```js
+{
+  options: string[],       // list of poll options in insertion order
+  votes: { [option]: number }, // vote count per option
+  deadline: number | null  // Unix timestamp (ms) when voting closes, or null
+}
+```
+
+### URL-based sharing
+
+Each document gets a unique Automerge URL (e.g. `automerge:abc123...`) stored in the page's URL hash. Opening the same URL in any browser loads and syncs the same document. Creating a new poll generates a new document and updates the hash automatically.
+
+### Voting rules
+
+- Voted options are tracked in `localStorage` (keyed by document URL), so they persist across page refreshes but are isolated per browser.
+- One vote per option per user. Votes can be toggled off and back on until the timer expires.
+- The timer (`doc.deadline`) is set once by whoever clicks "Start 2-min Vote" and is shared via the Automerge document, so all peers use the same deadline.
+
+## Running locally
+
+```bash
+pnpm install
+pnpm dev
+```
+
+Open the printed localhost URL. To test cross-browser sync, copy the URL (including the `#automerge:...` hash) and open it in a different browser.

app.js

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+import {
+  Repo,
+  BroadcastChannelNetworkAdapter,
+  WebSocketClientAdapter,
+  IndexedDBStorageAdapter,
+  isValidAutomergeUrl,
+} from "@automerge/vanillajs";
+
+const REPO = new Repo({
+  network: [
+    new BroadcastChannelNetworkAdapter(),
+    new WebSocketClientAdapter("wss://sync.automerge.org"),
+  ],
+  storage: new IndexedDBStorageAdapter(),
+});
+
+let HANDLE;
+
+function getVotedKey(docUrl) {
+  return `p2p-poll-voted:${docUrl}`;
+}
+
+function getVotedOptions() {
+  const key = getVotedKey(document.location.hash);
+  return new Set(JSON.parse(localStorage.getItem(key) || "[]"));
+}
+
+function markVoted(opt) {
+  const key = getVotedKey(document.location.hash);
+  const voted = getVotedOptions();
+  voted.add(opt);
+  localStorage.setItem(key, JSON.stringify([...voted]));
+}
+
+function unmarkVoted(opt) {
+  const key = getVotedKey(document.location.hash);
+  const voted = getVotedOptions();
+  voted.delete(opt);
+  localStorage.setItem(key, JSON.stringify([...voted]));
+}
+
+const locationHash = document.location.hash.substring(1);
+const statusEl = document.getElementById("status");
+const optionsList = document.getElementById("options-list");
+const optionInput = document.getElementById("option-input");
+const addBtn = document.getElementById("add-btn");
+const duplicateMsg = document.getElementById("duplicate-msg");
+const copyBtn = document.getElementById("copy-btn");
+const timerEl = document.getElementById("timer");
+const startVotingBtn = document.getElementById("start-voting-btn");
+
+if (isValidAutomergeUrl(locationHash)) {
+  statusEl.textContent = "Loading document…";
+  try {
+    HANDLE = await REPO.find(locationHash);
+    statusEl.textContent = "";
+  } catch (err) {
+    statusEl.textContent = "Could not load document. Starting a new one.";
+    HANDLE = REPO.create({ options: [], votes: {}, deadline: null });
+    document.location.hash = HANDLE.url;
+  }
+} else {
+  HANDLE = REPO.create({ options: [], votes: {}, deadline: null });
+  document.location.hash = HANDLE.url;
+}
+
+HANDLE.on("change", ({ doc }) => render(doc));
+
+const initialDoc = HANDLE.doc();
+if (initialDoc) render(initialDoc);
+
+let timerInterval = null;
+
+function render(doc) {
+  renderOptions(doc);
+  renderTimer(doc);
+}
+
+function renderOptions(doc) {
+  const votes = doc.votes || {};
+  const deadline = doc.deadline ?? null;
+  const now = Date.now();
+  const votingClosed = deadline !== null && now >= deadline;
+  const votedOptions = getVotedOptions();
+
+  const sorted = [...(doc.options || [])].sort(
+    (a, b) => (votes[b] || 0) - (votes[a] || 0),
+  );
+
+  optionsList.innerHTML = "";
+  sorted.forEach((opt) => {
+    const count = votes[opt] || 0;
+    const alreadyVoted = votedOptions.has(opt);
+
+    const item = document.createElement("div");
+    item.className = "option-item";
+
+    const label = document.createElement("span");
+    label.className = "option-label";
+    label.textContent = opt;
+
+    const voteBtn = document.createElement("button");
+    voteBtn.className = alreadyVoted ? "vote-btn voted" : "vote-btn";
+    voteBtn.textContent = alreadyVoted ? `✓ ${count}` : `▲ ${count}`;
+    voteBtn.disabled = votingClosed;
+    if (votingClosed) voteBtn.title = "Voting is closed";
+    else if (alreadyVoted) voteBtn.title = "Click to remove your vote";
+
+    voteBtn.addEventListener("click", () => {
+      if (alreadyVoted) {
+        unmarkVoted(opt);
+        HANDLE.change((d) => {
+          if (!d.votes) d.votes = {};
+          d.votes[opt] = Math.max(0, (d.votes[opt] || 0) - 1);
+        });
+      } else {
+        markVoted(opt);
+        HANDLE.change((d) => {
+          if (!d.votes) d.votes = {};
+          d.votes[opt] = (d.votes[opt] || 0) + 1;
+        });
+      }
+    });
+
+    item.appendChild(label);
+    item.appendChild(voteBtn);
+    optionsList.appendChild(item);
+  });
+}
+
+function renderTimer(doc) {
+  const deadline = doc?.deadline ?? null;
+  const now = Date.now();
+
+  if (deadline === null) {
+    timerEl.textContent = "";
+    startVotingBtn.hidden = false;
+    return;
+  }
+
+  startVotingBtn.hidden = true;
+
+  if (now >= deadline) {
+    timerEl.textContent = "Voting closed.";
+    timerEl.className = "timer closed";
+    clearInterval(timerInterval);
+    timerInterval = null;
+    return;
+  }
+
+  const remaining = Math.ceil((deadline - now) / 1000);
+  const mins = Math.floor(remaining / 60);
+  const secs = remaining % 60;
+  timerEl.textContent = `Voting closes in ${mins}:${secs.toString().padStart(2, "0")}`;
+  timerEl.className = "timer active";
+
+  if (!timerInterval) {
+    timerInterval = setInterval(() => {
+      const d = HANDLE.doc();
+      if (!d) return;
+      renderTimer(d);
+      renderOptions(d);
+      if (Date.now() >= d.deadline) {
+        clearInterval(timerInterval);
+        timerInterval = null;
+      }
+    }, 1000);
+  }
+}
+
+startVotingBtn.addEventListener("click", () => {
+  HANDLE.change((d) => {
+    d.deadline = Date.now() + 2 * 60 * 1000;
+  });
+});
+
+addBtn.addEventListener("click", () => {
+  const value = optionInput.value.trim();
+  if (!value) return;
+
+  const doc = HANDLE.doc();
+  const valueLower = value.toLowerCase();
+  const isDuplicate = (doc?.options || []).some(
+    (opt) => opt.toLowerCase() === valueLower,
+  );
+
+  if (isDuplicate) {
+    duplicateMsg.textContent = `"${value}" is already in the list.`;
+    duplicateMsg.hidden = false;
+    return;
+  }
+
+  duplicateMsg.hidden = true;
+  HANDLE.change((d) => {
+    if (!d.options) d.options = [];
+    d.options.push(value);
+  });
+  optionInput.value = "";
+});
+
+optionInput.addEventListener("keydown", (e) => {
+  if (e.key === "Enter") addBtn.click();
+});
+
+optionInput.addEventListener("input", () => {
+  duplicateMsg.hidden = true;
+});
+
+copyBtn.addEventListener("click", () => {
+  navigator.clipboard.writeText(window.location.href).then(() => {
+    copyBtn.textContent = "Copied!";
+    setTimeout(() => (copyBtn.textContent = "Copy URL"), 1500);
+  });
+});

index.html

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+<!doctype html>
+<html lang="en">
+    <head>
+        <meta charset="UTF-8" />
+        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+        <title>P2P Polling App</title>
+        <link rel="stylesheet" href="./styles.css" />
+    </head>
+    <body>
+        <div id="app">
+            <h1>P2P Polling App</h1>
+            <div id="status"></div>
+            <div id="add-option">
+                <input
+                    type="text"
+                    id="option-input"
+                    placeholder="Enter an option..."
+                />
+                <button id="add-btn">Add Option</button>
+            </div>
+            <div id="duplicate-msg" hidden></div>
+            <div id="timer-section">
+                <div id="timer"></div>
+                <button id="start-voting-btn">Start 2-min Vote</button>
+            </div>
+            <div id="options-list"></div>
+            <button id="copy-btn">Copy URL</button>
+        </div>
+        <script type="module" src="./app.js"></script>
+    </body>
+</html>

package.json

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+{
+  "name": "p2p-poll-app",
+  "type": "module",
+  "engines": {
+    "node": ">=24"
+  },
+  "scripts": {
+    "dev": "vite",
+    "build": "vite build",
+    "preview": "vite preview"
+  },
+  "dependencies": {
+    "@automerge/automerge-repo": "^2.0.0",
+    "@automerge/automerge-repo-network-websocket": "^2.0.0",
+    "@automerge/automerge-repo-storage-indexeddb": "^2.0.0",
+    "@automerge/vanillajs": "^2.5.3"
+  },
+  "devDependencies": {
+    "vite": "^6.0.0",
+    "vite-plugin-top-level-await": "^1.4.0",
+    "vite-plugin-wasm": "^3.3.0"
+  }
+}

styles.css

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+body {
+    font-family: sans-serif;
+    max-width: 480px;
+    margin: 40px auto;
+    padding: 0 16px;
+}
+
+#add-option {
+    display: flex;
+    gap: 8px;
+    margin-bottom: 8px;
+}
+
+#option-input {
+    flex: 1;
+    padding: 8px;
+    font-size: 1rem;
+    border: 1px solid #ccc;
+    border-radius: 4px;
+}
+
+#duplicate-msg {
+    color: #c00;
+    font-size: 0.9rem;
+    margin-bottom: 12px;
+}
+
+button {
+    padding: 8px 16px;
+    font-size: 1rem;
+    cursor: pointer;
+    border: 1px solid #ccc;
+    border-radius: 4px;
+    background: #fff;
+}
+
+button:hover:not(:disabled) {
+    background: #f0f0f0;
+}
+
+button:disabled {
+    opacity: 0.5;
+    cursor: default;
+}
+
+#timer-section {
+    display: flex;
+    align-items: center;
+    gap: 12px;
+    margin-bottom: 16px;
+}
+
+.timer.active {
+    font-weight: bold;
+    color: #1a6e1a;
+}
+
+.timer.closed {
+    font-weight: bold;
+    color: #c00;
+}
+
+.option-item {
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    padding: 10px 12px;
+    border: 1px solid #ddd;
+    border-radius: 4px;
+    margin-bottom: 8px;
+}
+
+.option-label {
+    flex: 1;
+}
+
+.vote-btn {
+    padding: 4px 12px;
+    font-size: 0.9rem;
+    white-space: nowrap;
+}
+
+.vote-btn.voted {
+    background: #e6f4e6;
+    border-color: #4a9e4a;
+    color: #2a6e2a;
+}
+
+
+#copy-btn {
+    margin-top: 16px;
+    width: 100%;
+}

vite.config.js

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+import { defineConfig } from 'vite'
+import wasm from 'vite-plugin-wasm'
+import topLevelAwait from 'vite-plugin-top-level-await'
+
+export default defineConfig({
+  plugins: [wasm(), topLevelAwait()]
+})