feat: 增加共享 Agent Browser 调试能力

需求：在 AI 编程会话中让用户与 Agent 共享同一浏览器页面，并查看控制台与网络信息。

实现：新增沙箱浏览器内核、Host API/渲染器面板、OpenCode 工具接入及安全边界测试。

electron/agent-browser/payload-store.ts

@@ -0,0 +1,167 @@
+import { randomUUID } from 'node:crypto';
+import type {
+  AgentBrowserPayloadChunk,
+  AgentBrowserPayloadRef,
+} from '../../shared/agent-browser';
+import { AgentBrowserFault } from './fault';
+
+type PayloadContentType = AgentBrowserPayloadRef['contentType'];
+
+interface PayloadEntry {
+  data: Buffer;
+  contentType: PayloadContentType;
+  expiresAt: number;
+}
+
+export interface PayloadStoreOptions {
+  maxBytes?: number;
+  maxEntryBytes?: number;
+  ttlMs?: number;
+  now?: () => number;
+}
+
+const DEFAULT_MAX_BYTES = 64 * 1024 * 1024;
+const DEFAULT_MAX_ENTRY_BYTES = 32 * 1024 * 1024;
+const DEFAULT_TTL_MS = 60_000;
+const DEFAULT_CHUNK_BYTES = 256 * 1024;
+const MAX_CHUNK_BYTES = 1024 * 1024;
+
+export class AgentBrowserPayloadStore {
+  private readonly entries = new Map<string, PayloadEntry>();
+  private readonly maxBytes: number;
+  private readonly maxEntryBytes: number;
+  private readonly ttlMs: number;
+  private readonly now: () => number;
+  private totalBytes = 0;
+
+  constructor(options: PayloadStoreOptions = {}) {
+    this.maxBytes = options.maxBytes ?? DEFAULT_MAX_BYTES;
+    this.maxEntryBytes = options.maxEntryBytes ?? DEFAULT_MAX_ENTRY_BYTES;
+    this.ttlMs = options.ttlMs ?? DEFAULT_TTL_MS;
+    this.now = options.now ?? Date.now;
+  }
+
+  putJson(value: unknown): AgentBrowserPayloadRef {
+    let encoded: Buffer;
+    try {
+      encoded = Buffer.from(JSON.stringify(value) ?? 'null');
+    } catch {
+      throw new AgentBrowserFault(
+        'CDP_PROTOCOL_ERROR',
+        'CDP 返回了无法序列化的数据。',
+        false,
+      );
+    }
+    return this.put(encoded, 'application/json');
+  }
+
+  put(data: Buffer, contentType: PayloadContentType): AgentBrowserPayloadRef {
+    this.purgeExpired();
+    if (data.byteLength > this.maxEntryBytes || data.byteLength > this.maxBytes) {
+      throw new AgentBrowserFault(
+        'PAYLOAD_TOO_LARGE',
+        `CDP 数据超过 ${this.maxEntryBytes} 字节的单项上限。`,
+        false,
+      );
+    }
+
+    while (this.totalBytes + data.byteLength > this.maxBytes) {
+      const oldest = this.entries.keys().next().value as string | undefined;
+      if (!oldest) break;
+      this.delete(oldest);
+    }
+
+    const handle = randomUUID();
+    const expiresAt = this.now() + this.ttlMs;
+    this.entries.set(handle, {
+      data: Buffer.from(data),
+      contentType,
+      expiresAt,
+    });
+    this.totalBytes += data.byteLength;
+    return {
+      kind: 'payload',
+      handle,
+      byteLength: data.byteLength,
+      contentType,
+      expiresAt: new Date(expiresAt).toISOString(),
+    };
+  }
+
+  read(handle: string, offset = 0, maxBytes = DEFAULT_CHUNK_BYTES): AgentBrowserPayloadChunk {
+    this.purgeExpired();
+    const entry = this.entries.get(handle);
+    if (!entry) {
+      throw new AgentBrowserFault(
+        'PAYLOAD_NOT_FOUND',
+        'CDP 数据已过期或不存在。',
+        false,
+      );
+    }
+    if (!Number.isInteger(offset) || offset < 0 || offset > entry.data.byteLength) {
+      throw new AgentBrowserFault('INVALID_REQUEST', 'Payload offset 无效。', false);
+    }
+    if (!Number.isInteger(maxBytes) || maxBytes < 1) {
+      throw new AgentBrowserFault('INVALID_REQUEST', 'Payload maxBytes 无效。', false);
+    }
+
+    const requestedBytes = Math.min(
+      maxBytes,
+      MAX_CHUNK_BYTES,
+    );
+    let nextOffset = Math.min(offset + requestedBytes, entry.data.byteLength);
+    const isText = entry.contentType !== 'application/octet-stream';
+    if (isText && offset > 0 && (entry.data[offset] & 0xc0) === 0x80) {
+      throw new AgentBrowserFault(
+        'INVALID_REQUEST',
+        '文本 Payload offset 必须位于 UTF-8 字符边界。',
+        false,
+      );
+    }
+    if (isText && nextOffset < entry.data.byteLength) {
+      while (nextOffset > offset && (entry.data[nextOffset] & 0xc0) === 0x80) {
+        nextOffset -= 1;
+      }
+      if (nextOffset === offset) {
+        nextOffset = Math.min(offset + requestedBytes, entry.data.byteLength);
+        while (
+          nextOffset < entry.data.byteLength
+          && (entry.data[nextOffset] & 0xc0) === 0x80
+        ) {
+          nextOffset += 1;
+        }
+      }
+    }
+
+    const chunk = entry.data.subarray(offset, nextOffset);
+    return {
+      handle,
+      offset,
+      nextOffset,
+      byteLength: entry.data.byteLength,
+      contentType: entry.contentType,
+      data: isText ? chunk.toString('utf8') : chunk.toString('base64'),
+      encoding: isText ? 'utf8' : 'base64',
+      done: nextOffset >= entry.data.byteLength,
+    };
+  }
+
+  delete(handle: string): void {
+    const entry = this.entries.get(handle);
+    if (!entry) return;
+    this.entries.delete(handle);
+    this.totalBytes -= entry.data.byteLength;
+  }
+
+  clear(): void {
+    this.entries.clear();
+    this.totalBytes = 0;
+  }
+
+  private purgeExpired(): void {
+    const now = this.now();
+    for (const [handle, entry] of this.entries) {
+      if (entry.expiresAt <= now) this.delete(handle);
+    }
+  }
+}