Narrow browser and extension FFI messages / 收窄浏览器与扩展 FFI 消息

[tiye]

English

Problem

After #36 removes the false Store decoder boundary and local alerts uses precise nominal hook schemas, seven msg-buffer-owned current-compiler findings remain:

• Two event handlers dereference .-target from JsNullish values without narrowing.
• main! compares raw document.visibilityState with a String.
• listen-extension! compares four raw message.action values with Strings (menu-summary, fill-text, menu-translate, menu-custom).

These are all shallow host-boundary values and should not stay Dynamic inside application control flow.

Proposed migration

• Define typed browser-event/message adapters that validate target/action/visibility fields at ingress.
• Return Option<String> or a finite nominal action enum; pattern-match before dispatch.
• Keep arbitrary deep extension payload data Dynamic only behind the decoded action-specific boundary.

Acceptance

• No direct dereference of JsNullish event targets.
• Visibility and extension action comparisons are statically homogeneous or nominal matches.
• Existing send/reply/fill/translate behavior and startup output remain unchanged.
• Do not solve the migration with broad unsafe-coerce or raw equality primitives.

中文

问题

#36 删除错误的 Store decoder 边界，并让本地 alerts 使用精确 nominal hook schema 后，当前编译器仍报告 7 条由 msg-buffer 自身负责的问题：

• 两个事件 handler 未 narrow 就从 JsNullish 值读取 .-target。
• main! 把原始 document.visibilityState 与 String 比较。
• listen-extension! 把四个原始 message.action 与 String 比较（menu-summary、fill-text、menu-translate、menu-custom）。

这些都是浅层 host-boundary 值，不应以 Dynamic 继续进入应用控制流。

建议迁移

• 定义 typed browser-event/message adapter，在入口验证 target/action/visibility 字段。
• 返回 Option<String> 或有限 nominal action enum，并在 dispatch 前 pattern match。
• 只有 action-specific 边界之后的任意深层 extension payload 才保留 Dynamic。

验收

• 不再直接解引用 JsNullish event target。
• visibility 与 extension action 使用静态同类型比较或 nominal match。
• 现有发送、reply、fill、translate 行为与启动输出保持不变。
• 不用宽泛 unsafe-coerce 或底层 raw equality primitive 规避迁移。