refactor(bridge): migrate gravity bridge to pure websocket gateway architecture, deleting legacy local file scanners and dependencies

extension/src/brain-watcher.ts

@@ -0,0 +1,96 @@
+import * as fs from 'fs';
+import * as path from 'path';
+import * as os from 'os';
+import { WSBridgeClient } from './ws-client';
+
+export interface BrainWatcherContext {
+    logToFile: (msg: string) => void;
+    wsBridge: WSBridgeClient;
+    projectName: string;
+}
+
+export class BrainWatcher {
+    private brainDir: string;
+    private ctx: BrainWatcherContext;
+    private currentSessionId: string = '';
+    private watcher: fs.FSWatcher | null = null;
+    private lastEventTimes: Map<string, number> = new Map();
+
+    constructor(ctx: BrainWatcherContext) {
+        this.ctx = ctx;
+        // The bridgePath is ~/.gemini/antigravity/bridge, so brain is sibling
+        this.brainDir = path.join(os.homedir(), '.gemini', 'antigravity', 'brain');
+    }
+
+    public updateSession(sessionId: string) {
+        if (!sessionId || this.currentSessionId === sessionId) {
+            return;
+        }
+        this.currentSessionId = sessionId;
+        this.startWatching(sessionId);
+    }
+
+    private startWatching(sessionId: string) {
+        this.stop();
+
+        const sessionDir = path.join(this.brainDir, sessionId);
+        if (!fs.existsSync(sessionDir)) {
+            // It might not be created yet, poll gently
+            setTimeout(() => this.startWatching(sessionId), 2000);
+            return;
+        }
+
+        try {
+            this.watcher = fs.watch(sessionDir, { persistent: false }, (eventType, filename) => {
+                if (!filename || !filename.endsWith('.md')) return;
+
+                // Dedup rapid events
+                const now = Date.now();
+                const last = this.lastEventTimes.get(filename) || 0;
+                if (now - last < 500) return; // 500ms debounce
+                this.lastEventTimes.set(filename, now);
+
+                this.handleFileChange(sessionDir, filename, eventType);
+            });
+            this.ctx.logToFile(`[BRAIN-WATCHER] Started watching session: ${sessionId.substring(0, 8)}`);
+        } catch (e: any) {
+            this.ctx.logToFile(`[BRAIN-WATCHER] Failed to watch ${sessionId}: ${e.message}`);
+        }
+    }
+
+    private handleFileChange(dir: string, filename: string, rawEventType: string) {
+        const filePath = path.join(dir, filename);
+        let content = '';
+        let eventType = 'file_changed';
+
+        try {
+            if (fs.existsSync(filePath)) {
+                content = fs.readFileSync(filePath, 'utf-8');
+            } else {
+                eventType = 'file_deleted';
+            }
+        } catch (e) {
+            // File might be locked or deleted during read
+            return;
+        }
+
+        if (this.ctx.wsBridge && this.ctx.wsBridge.isConnected()) {
+            this.ctx.wsBridge.sendBrainEvent({
+                event_type: eventType,
+                conversation_id: this.currentSessionId,
+                file_name: filename,
+                content: content,
+                timestamp: Date.now() / 1000,
+                project_name: this.ctx.projectName,
+            });
+            this.ctx.logToFile(`[BRAIN-WATCHER] Sent ${eventType} for ${filename}`);
+        }
+    }
+
+    public stop() {
+        if (this.watcher) {
+            this.watcher.close();
+            this.watcher = null;
+        }
+    }
+}