优化: 子代理截断信号与缓存失效

- max_tokens 截断标记穿透到完成卡
- 缓存写后失效补测试锁定
- 派发参数卡头信息补全

src/i18n/en/aiTool.ts

@@ -117,6 +117,8 @@ export default {
     // fetch_url header display name (useToolCardHeader): host-shortened prefix + fallback when no url
     fetchUrlPrefix: 'Fetch',
     fetchUrlFallback: 'Fetch URL',
+    // spawn_agent header display name (P3-3: task truncated to 25 chars, consumes backend "dispatch sub-agent" goal metadata)
+    spawnAgentPrefix: 'Spawn agent: {task}',
     installObscura: 'Install obscura via AI',
     obscuraInstallPrompt: 'Please install obscura (a Rust headless browser, used by fetch_url render=true for JS rendering). Try `cargo install obscura` first; if cargo is unavailable, download the prebuilt binary for this platform from the GitHub releases (github.com/h4ckf0r0day/obscura) and place it on PATH. After installing, verify with `obscura --version` and tell me I can retry the web fetch.',
     // grep cross-file content search results per output_mode phrasing