CMMS fork: pcb AI bridge — robustness for the first-message race

The chat's get-buffer request can arrive before studio.js init() has
built the DB / selected a board (or while an existing project ZIP is
still streaming in), which read back as "the editor is still loading".

- buildProjectView() waits up to 4.5s for db + a board, then still
  returns a valid (possibly empty) project view with a "no board open"
  note rather than null - only a missing db is "still loading".
- init() with no loadUrl (a "+ New board RE") now ensures a starter
  board exists (studio.js only auto-creates one when the whole DB is
  empty, not when the selected device just has no boards).
- reply prefers evt.source, falls back to a DOM query for the chat
  iframe (cad-editor hit an unusable cross-realm Window).
- [cmms-pcb-bridge] console tracing on every step.

docs/cmms-bridge.js

@@ -113,19 +113,41 @@
 
 	// ---- AI Assistant editor-buffer bridge -------------------------------
 	// The chat embed (an iframe) postMessages here; this top-level page is the
-	// "editor" side of the cmms-ai-editor-* protocol (like cad-editor's Rust
+	// "editor" side of the cmms-ai-editor-* protocol (like cad-editor, whose
-	// listener). read: serialise the open board; apply: merge a JSON patch of
+	// WASM app is also the top-level page). read: serialise the open board;
-	// proposed components + nets. Nothing is saved.
+	// apply: merge a JSON patch of proposed components + nets. Nothing is saved.
+	const trace = (...a) => { try { console.log('[cmms-pcb-bridge]', ...a); } catch (e) {} };
+
+	// The chat's get-buffer request can land before studio.js's init() has
+	// finished creating the DB and selecting a board (or while an existing
+	// project ZIP is still downloading). Wait briefly rather than replying
+	// "not ready" - the widget times out at 2.5s, so stay under that.
+	const ready = () => !!(db && currentBomId);
+	async function waitReady(ms) {
+		const t0 = Date.now();
+		while (!ready() && Date.now() - t0 < ms) {
+			await new Promise(r => setTimeout(r, 100));
+		}
+		return ready();
+	}
 
 	async function buildProjectView() {
-		if (!currentDeviceId || !currentBomId) return null;
+		// The widget waits 6s for a pcb reply (ai-assistant-widget.js); stay
+		// under that so a "still initialising" answer still gets through.
+		if (!(await waitReady(4500))) {
+			trace('buildProjectView: db/board not ready after 4.5s (db:', !!db, 'board:', !!currentBomId, ')');
+			// db exists but no board -> a real (empty) project the model can
+			// still work from; only a missing db means "still loading".
+			if (!db) return null;
+		}
 		const dev = deviceList.find(d => d.id === currentDeviceId);
 		const board = bomList.find(b => b.id === currentBomId);
-		const allNets = await db.getNets();
+		const allNets = currentBomId ? await db.getNets() : [];
 		const nets = allNets.filter(n => n.projectId === currentBomId);
-		return JSON.stringify({
+		const view = {
 			device: dev ? dev.name : null,
 			board: board ? board.name : null,
+			note: currentBomId ? undefined : 'No board is open yet - the user needs to create or select one before components/nets can be added.',
 			image_count: bomImages.length,
 			images: bomImages.map(i => ({ id: i.id, name: i.name || '' })),
 			components: bomData.map(c => ({
@@ -133,7 +155,9 @@
 				x: Math.round(c.x), y: Math.round(c.y),
 			})),
 			nets: nets.map(n => ({ name: n.name, pins: (n.nodes || []).map(nd => nd.label) })),
-		});
+		};
+		trace('buildProjectView:', view.components.length, 'components,', view.nets.length, 'nets,', view.image_count, 'photos');
+		return JSON.stringify(view);
 	}
 
 	async function applyProjectPatch(patchJson) {
@@ -184,22 +208,57 @@
 		status(`AI proposal applied (${nc} component${nc === 1 ? '' : 's'}, ${nn} net${nn === 1 ? '' : 's'}) — check each against the photo, then Save`);
 	}
 
+	// Reply to the chat iframe. Prefer evt.source; fall back to a DOM query
+	// (cad-editor hit a case where event.source was an unusable cross-realm
+	// Window - belt and braces here too).
+	function replyToChat(evtSource, msg) {
+		let posted = false;
+		try { if (evtSource && evtSource.postMessage) { evtSource.postMessage(msg, window.location.origin); posted = true; } } catch (e) {}
+		if (!posted) {
+			const f = document.querySelector('#ai-assistant-editor-embed iframe');
+			try { if (f && f.contentWindow) { f.contentWindow.postMessage(msg, window.location.origin); posted = true; } } catch (e) {}
+		}
+		trace('reply', msg.type, posted ? 'sent' : 'DROPPED');
+	}
+
 	window.addEventListener('message', async (evt) => {
 		if (evt.origin !== window.location.origin || !evt.data || typeof evt.data !== 'object') return;
 		const d = evt.data;
 		if (d.type === 'cmms-ai-editor-get-buffer') {
+			trace('get-buffer received');
 			let buffer = null;
-			try { buffer = await buildProjectView(); } catch (e) { /* reply null */ }
+			try { buffer = await buildProjectView(); } catch (e) { trace('buildProjectView threw:', e && e.message); }
-			try { evt.source.postMessage({ type: 'cmms-ai-editor-buffer', buffer: buffer }, window.location.origin); } catch (e) {}
+			replyToChat(evt.source, { type: 'cmms-ai-editor-buffer', buffer: buffer });
 		} else if (d.type === 'cmms-ai-editor-apply' && d.editor === 'pcb' && typeof d.new_source === 'string') {
+			trace('apply received');
 			try {
 				await applyProjectPatch(d.new_source);
 			} catch (e) {
+				trace('applyProjectPatch threw:', e && e.message);
 				status('Could not apply the AI proposal: ' + (e.message || e), true);
 			}
 		}
 	});
 
+	// A "+ New board RE" launch with no board on the selected device (studio.js
+	// only auto-creates one when the whole DB is empty) - make one so the user
+	// lands on a working board, not an empty "No Boards" shell.
+	async function ensureBoard() {
+		if (currentBomId) return;
+		let devId = currentDeviceId;
+		if (!devId || !deviceList.find(d => d.id === devId)) {
+			devId = uuid();
+			await db.addDevice({ id: devId, name: 'Board' });
+			currentDeviceId = devId;
+			try { localStorage.setItem('pcb_device_id', devId); } catch (e) {}
+		}
+		await db.addProject({ id: uuid(), deviceId: devId, name: 'Board 1', sortMode: 'none' });
+		deviceList = await db.getDevices();
+		updateDeviceDropdown();
+		await loadDeviceBoms();
+		trace('ensureBoard: created a starter board');
+	}
+
 	async function init() {
 		if (CFG.dark) document.documentElement.setAttribute('data-theme', 'dark');
 		injectControls();
@@ -215,6 +274,8 @@
 			} catch (e) {
 				status('Could not load the saved board: ' + (e.message || e), true);
 			}
+		} else {
+			try { await ensureBoard(); } catch (e) { trace('ensureBoard threw:', e && e.message); }
 		}
 	}