fix(tools): widen the Unicode-skew obligation past isBareIdentifier

The predicate is not the only reader of the engine's XID tables. camelCase
reads them through its split set and its head test, and the class name it
derives is emitted for EVERY tool -- including one the predicate rejected,
whose TypedDict is still declared and named. A tool named `zz-` + U+1E4D0
never reaches the skew in the predicate, since the `-` rejects it outright,
yet still emits `class Zz<U+1E4D0>xArgs`, which CPython 3.9.6 refuses the
same way. A backend PR executing "pin the predicate against tables for the
floor" literally would leave that path open, so the note and the docstring
now name all three read points.

Two corrections in the same paragraph. The failing direction is a character
added to XID_Start OR XID_Continue -- one added only to the latter passes
the trailing `\p{XID_Continue}*` in a tail position and fails identically.
And the safe direction routes a name to the subscript/`dict[str, Any]`
path: a rejected FIELD name degrades its whole enclosing object rather than
just itself, which the predicate's opening paragraph already said.

Also qualify the module header's "ONLY source" claim, which holds under
`mode: 'code'` but not `both`, where wireSchemas ships every native schema
alongside the SDK section; record the measured str.isidentifier()
equivalence (21 samples, zero divergence, Node 22.23.1 vs CPython 3.9.6)
where the versions it is relative to already live; and attribute the
`FInd` spelling in the ligature test to full case mapping rather than to
the NFKC step, which is the identity there.

Two tests. The fold-collision half of the childClassName fix: sibling joins
that are byte-distinct before NFKC and equal after, so `usedClassNames`
dedupes by raw bytes and the counter only sees the collision because the
join is normalized. And the argument-side oneOf-of-objects branch naming,
which reaches the same childClassName path the output side already pins.

.agents/notes/implemented/feature/2026-07-31-code-mode-language-dispatch.zh.md

@@ -43,4 +43,4 @@ Code Mode 只生成一种 SDK 形态：TypeScript。`ToolRegistry` 为 `tools:sd
 
 Python SDK 文本断言的两条运行时契约同样归属那个 backend PR。其一，说明文字告诉模型运行时恰好绑定 `tools` 与 `ToolCallError` 两个名字、所声明的 `TypedDict` 类不绑定，因此后端必须注入这两个名字（并按 seam 的 `errorClass` 契约填充 `ToolCallError.toolName`），且**不得**把所声明的类名绑进程序全局——「好心」注入会使这段 SDK 文本变成假话。其二，语言必须绑定到请求上：`requireCodeRuntime` 在组装时与 `run_code` 执行时分别解析 `ctx.codeRuntime`，若在这两点之间发生重载并换掉运行时，就会把针对一种形态写成的程序交给另一种形态执行。分裂比这两点更细——`run_code` 的 `description` 与 `parameters` 两个 getter 各自调用 `resolveFlavor(peekRuntime())`，而 `schemaOf` 会解构这两个字段，因此一次投影读两次运行时；两次都属于 `run_code` 自己的 schema，因为这两个 getter 只装在那一个 definition 上，其余 definition 携带的都是普通数据属性。在这两次读取之间重载会产出单个 schema 的两半分属不同语言。两者在此处都不可达——只有一个已发布后端意味着两次读取返回同一形态，且没有任何程序会针对本渲染器的输出运行——而跨语言拒绝在第二门语言存在之前也无法测试。
 
-其三，那个 PR 拥有 CPython 版本下限，连带拥有 `isBareIdentifier` 里的 Unicode 表偏斜。本渲染器用所运行引擎的 `\p{XID_Start}`/`\p{XID_Continue}` 表（Node 22.23.1：Unicode 17.0）决定某个字段名或工具名能否裸发，而解释器用它自己的表（CPython 3.9.6：13.0.0）。解释器旧于引擎是会失败的那个方向：在两者之间被加进 `XID_Start` 的字符会被裸发，其 tokenizer 拒收，整个块随之不可解析。暴露窗口恰是两个版本之间新增的那些字符，所以宣布支持某个 CPython 范围的那个 PR 必须在「接受该暴露」与「按该下限的固定表收紧判据」之间显式作出决定。此处无法决定：下限尚不存在，而按猜测钉死一张表会成为一个随部署而变、却没有可配置性支撑的常量。
+其三，那个 PR 拥有 CPython 版本下限，连带拥有本渲染器的 Unicode 表偏斜。有三个正则读所运行引擎的表（Node 22.23.1：Unicode 17.0），而解释器用它自己的表（CPython 3.9.6：13.0.0）：`isBareIdentifier` 的 `IDENTIFIER`，以及 `camelCase` 的切分集与头部测试。解释器旧于引擎是会失败的那个方向——在两者之间被加进 `XID_Start` 或 `XID_Continue` 的字符会被发出，其 tokenizer 拒收，整个块随之不可解析——而它经两条独立路径抵达。经判据抵达的是裸发的方法名或字段名。经 `camelCase` 抵达的是类名，而类名对每个工具都发出，包括被判据拒绝的那些：工具名 `zz-` 加 U+1E4D0 因 `-` 被判据直接拒绝、从不触及那里的偏斜，却照样声明 `class Zz𞓐xArgs`。暴露窗口恰是两个版本之间新增的那些字符，所以宣布支持某个 CPython 范围的那个 PR 必须在「接受该暴露」与「按该下限的表钉住全部三个读取点」之间显式作出决定——只钉判据会留下类名那条路径。此处无法决定：下限尚不存在，而按猜测钉死一张表会成为一个随部署而变、却没有可配置性支撑的常量。