Extension: per-machine default tablet, skip asking unless busy

- Options page gains a 'Default tablet for this machine' picker,
  populated from the device list once base URL + terminal key are
  configured, auto-saved on change (small enough setting not to warrant
  its own Save button).
- Popup pre-selects the default in its device dropdown but still shows
  the full picker — opening the popup is already a deliberate action, so
  staff can still override it there.
- Injected buttons (row + banner) skip the dropdown entirely when a
  default is configured — one click pushes straight to it. Only falls
  back to the full picker if that specific push comes back busy (409),
  with a note explaining why it's asking despite a default being set.
  background.js's pushBooking() now returns the HTTP status alongside
  ok/error so this can be detected reliably rather than string-matching
  the error message.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/extension-src/background.js

@@ -103,8 +103,11 @@ async function pushBooking(bookingId, deviceId) {
       body: JSON.stringify({ booking_id: bookingId, device_id: deviceId }),
     });
     const body = await res.json().catch(() => ({}));
-    if (!res.ok) return { ok: false, error: body.error || `HTTP ${res.status}` };
-    return { ok: true };
+    // status included so callers can reliably tell "device busy" (409) apart
+    // from other failures — used by content-script.js's default-tablet
+    // fast-path to decide whether to fall back to the device picker.
+    if (!res.ok) return { ok: false, status: res.status, error: body.error || `HTTP ${res.status}` };
+    return { ok: true, status: res.status };
   } catch (err) {
     return { ok: false, error: err.message };
   }

backend/extension-src/content-script.js

@@ -89,14 +89,68 @@ function makeSendButton(bookingId, guestName, variant = 'block') {
   btn.addEventListener('click', e => {
     e.preventDefault();
     e.stopPropagation();
-    togglePanel(btn, bookingId, guestName, variant);
+    handleSendClick(btn, bookingId, guestName, variant);
   });
   return btn;
 }
 
+// Injected buttons skip asking which tablet entirely when a default is
+// configured for this machine (see options.js) — push straight to it. Only
+// falls back to the full device-picker panel if that specific push comes
+// back busy (409), or if no default is configured at all — see
+// project_checkin memory's extension notes, this was an explicit UX request
+// ("injected buttons don't need to ask which tablet, just use/send to
+// default unless busy"). The popup is deliberately different — it always
+// shows the picker, just pre-selected to the default (see popup.js) — since
+// opening the popup is already a more deliberate action than a one-click
+// inline button.
+async function handleSendClick(anchorBtn, bookingId, guestName, variant) {
+  const { defaultDeviceId } = await chrome.storage.local.get('defaultDeviceId');
+
+  if (defaultDeviceId) {
+    const status = showInlineStatus(anchorBtn, variant, 'Sending…');
+    const result = await chrome.runtime.sendMessage({
+      action: 'tcpPush', bookingId, deviceId: defaultDeviceId,
+    });
+    if (result?.ok) {
+      status.textContent = 'Sent — the tablet should navigate now.';
+      status.style.color = '#166534';
+      return;
+    }
+    if (result?.status === 409) {
+      status.remove();
+      // fall through to the picker below, with a note explaining why it's
+      // asking despite a default being configured
+      await togglePanel(anchorBtn, bookingId, guestName, variant, 'Default tablet is busy — choose another:');
+      return;
+    }
+    status.textContent = `Failed: ${result?.error || 'unknown error'}`;
+    status.style.color = '#dc2626';
+    return;
+  }
+
+  await togglePanel(anchorBtn, bookingId, guestName, variant);
+}
+
+// Small text-only status line for the default-tablet fast path — no
+// dropdown, nothing to pick, just feedback on what happened.
+function showInlineStatus(anchorBtn, variant, text) {
+  if (openPanel) { openPanel.remove(); openPanel = null; }
+  const el = document.createElement('div');
+  const width = variant === 'block' ? 'width: 100%;' : '';
+  el.style.cssText = `
+    display: block; margin-top: 6px; ${width} font-size: 12px; color: #64748b;
+    font-family: -apple-system, BlinkMacSystemFont, sans-serif;
+  `;
+  el.textContent = text;
+  anchorBtn.insertAdjacentElement('afterend', el);
+  openPanel = el;
+  return el;
+}
+
 let openPanel = null;
 
-async function togglePanel(anchorBtn, bookingId, guestName, variant = 'block') {
+async function togglePanel(anchorBtn, bookingId, guestName, variant = 'block', note = '') {
   if (openPanel) { openPanel.remove(); openPanel = null; }
 
   const panel = document.createElement('div');
@@ -111,7 +165,7 @@ async function togglePanel(anchorBtn, bookingId, guestName, variant = 'block') {
     font-family: -apple-system, BlinkMacSystemFont, sans-serif;
     font-size: 12px; color: #1e293b;
   `;
-  panel.textContent = 'Loading tablets…';
+  panel.textContent = note ? `${note} loading…` : 'Loading tablets…';
   anchorBtn.insertAdjacentElement('afterend', panel);
   openPanel = panel;
 
@@ -151,6 +205,12 @@ async function togglePanel(anchorBtn, bookingId, guestName, variant = 'block') {
   });
 
   panel.innerHTML = '';
+  if (note) {
+    const noteEl = document.createElement('div');
+    noteEl.textContent = note;
+    noteEl.style.cssText = 'margin-bottom: 6px; color: #b45309; font-weight: 600;';
+    panel.appendChild(noteEl);
+  }
   panel.appendChild(select);
   panel.appendChild(sendBtn);
 }

backend/extension-src/options/options.html

@@ -28,6 +28,16 @@
   <button id="test">Test connection</button>
   <p id="status"></p>
 
+  <div id="defaultTabletSection" style="display: none;">
+    <label for="defaultDevice">Default tablet for this machine</label>
+    <select id="defaultDevice"></select>
+    <p class="hint">
+      The popup pre-selects this tablet but still lets you pick a different one. The "Send to Tablet"
+      buttons injected into NewBook itself skip asking entirely and push straight to this tablet —
+      unless it's busy, in which case they fall back to asking which one to use.
+    </p>
+  </div>
+
   <script type="module" src="options.js"></script>
 </body>
 </html>

backend/extension-src/options/options.js

@@ -1,12 +1,62 @@
 const baseUrlInput = document.getElementById('baseUrl');
 const apiKeyInput = document.getElementById('apiKey');
 const statusEl = document.getElementById('status');
+const defaultSection = document.getElementById('defaultTabletSection');
+const defaultDeviceSelect = document.getElementById('defaultDevice');
 
 async function load() {
-  const { baseUrl, apiKey } = await chrome.storage.local.get(['baseUrl', 'apiKey']);
+  const { baseUrl, apiKey, defaultDeviceId } = await chrome.storage.local.get(['baseUrl', 'apiKey', 'defaultDeviceId']);
   if (baseUrl) baseUrlInput.value = baseUrl;
   if (apiKey) apiKeyInput.value = apiKey; // deliberately shown back here (options page,
   // not the popup) so the value can be corrected without regenerating the key.
+  if (baseUrl && apiKey) refreshDeviceList(defaultDeviceId);
+}
+
+// Shared by Test Connection and the default-tablet picker — one fetch, two
+// uses, rather than hitting the API twice for what's the same data.
+async function fetchDevices() {
+  const { baseUrl, apiKey } = await chrome.storage.local.get(['baseUrl', 'apiKey']);
+  if (!baseUrl || !apiKey) throw new Error('Set both fields and save first.');
+  const res = await fetch(`${baseUrl}/api/staff/devices`, {
+    headers: { Authorization: `Bearer ${apiKey}` },
+  });
+  const body = await res.json().catch(() => ([]));
+  if (!res.ok) throw new Error(body.error || `HTTP ${res.status}`);
+  return body;
+}
+
+// Populates the "default tablet for this machine" picker — see project_checkin
+// memory's extension notes: the popup pre-selects this but still lets staff
+// override it; the injected buttons skip asking entirely and push straight
+// to it unless it's busy. Selection auto-saves on change, no separate button
+// — it's a small enough setting not to warrant one.
+async function refreshDeviceList(preselectId) {
+  try {
+    const devices = await fetchDevices();
+    if (!devices.length) {
+      defaultSection.style.display = 'none';
+      return;
+    }
+    defaultDeviceSelect.innerHTML = devices.map(d =>
+      `<option value="${d.device_id}">${escapeHtml(d.name)}</option>`
+    ).join('');
+    if (preselectId) defaultDeviceSelect.value = preselectId;
+    defaultSection.style.display = '';
+  } catch {
+    // Not configured/reachable yet — leave the section hidden rather than
+    // showing an empty/broken picker; Test Connection surfaces the real error.
+    defaultSection.style.display = 'none';
+  }
+}
+
+defaultDeviceSelect.addEventListener('change', () => {
+  chrome.storage.local.set({ defaultDeviceId: defaultDeviceSelect.value });
+});
+
+function escapeHtml(s) {
+  const div = document.createElement('div');
+  div.textContent = s;
+  return div.innerHTML;
 }
 
 // tablet-checkin's own base URL isn't known in advance (dev today, a
@@ -33,28 +83,17 @@ async function save() {
   await chrome.storage.local.set({ baseUrl, apiKey });
   statusEl.textContent = 'Saved.';
   statusEl.style.color = '#16a34a';
+  refreshDeviceList();
 }
 
 async function test() {
-  const { baseUrl, apiKey } = await chrome.storage.local.get(['baseUrl', 'apiKey']);
-  if (!baseUrl || !apiKey) {
-    statusEl.textContent = 'Set both fields and save first.';
-    statusEl.style.color = '#dc2626';
-    return;
-  }
   statusEl.textContent = 'Testing…';
   statusEl.style.color = '#64748b';
   try {
-    const res = await fetch(`${baseUrl}/api/staff/devices`, {
-      headers: { Authorization: `Bearer ${apiKey}` },
-    });
-    if (!res.ok) {
-      const body = await res.json().catch(() => ({}));
-      throw new Error(body.error || `HTTP ${res.status}`);
-    }
-    const devices = await res.json();
+    const devices = await fetchDevices();
     statusEl.textContent = `Connected — found ${devices.length} tablet(s).`;
     statusEl.style.color = '#16a34a';
+    refreshDeviceList();
   } catch (err) {
     statusEl.textContent = `Failed: ${err.message}`;
     statusEl.style.color = '#dc2626';

backend/extension-src/popup/popup.js

@@ -20,7 +20,7 @@ async function main() {
     nbStatusEl.className = `nb-status ${ok ? 'ok' : 'no'}`;
   });
 
-  const { baseUrl, apiKey } = await chrome.storage.local.get(['baseUrl', 'apiKey']);
+  const { baseUrl, apiKey, defaultDeviceId } = await chrome.storage.local.get(['baseUrl', 'apiKey', 'defaultDeviceId']);
   if (!baseUrl || !apiKey) {
     contentEl.innerHTML = `
       <p class="muted">Not set up yet — add the tablet-checkin URL and a terminal API key first.</p>
@@ -72,6 +72,12 @@ async function main() {
       ${escapeHtml(d.name)}${d.status === 'busy' ? ' (busy)' : ''}
     </option>`
   ).join('');
+  // Pre-select this machine's configured default tablet — still just a
+  // starting point, staff can pick a different one from the dropdown.
+  // Setting .value to a disabled (busy) option is a no-op in every browser
+  // that matters here, so a busy default just falls through to whatever the
+  // browser's own first-enabled-option default would have been anyway.
+  if (defaultDeviceId) deviceSelect.value = defaultDeviceId;
   sendBtn.disabled = false;
 
   sendBtn.addEventListener('click', async () => {