docs(tools): align Code Mode docs with multi-language dispatch; py-types notes

Address ds-review-bot v5/v6 review round 3:
- Config.mode JSDoc and the regenerated config-catalog no longer claim Code
  Mode requires a TypeScript runtime; both now say a language with a
  registered SDK renderer.
- The active 2026-06-15-code-mode base note (both languages) follows shipped
  reality: the SDK renders the loaded runtime's language, dsh-tools accepts
  any language with a renderer and run_code flavor, and it cross-links the
  language-dispatch note.
- The language-dispatch note distinguishes the two Object.hasOwn guards'
  reachability and documents the peekRuntime no-runtime degrade vs the
  rejected silent fallback.
- SDK_RENDERERS comment: adding a language is two table entries, not one.
- py-types: document the deliberate PEP 586 deviation for float Literals;
  add oneOf-object-branch tests (named union classes and context-free
  degrade), keeping py-types.ts at 100% per-file coverage.

packages/core/tools/src/index.ts

@@ -31,7 +31,9 @@ import { renderToolsSdkPy } from './py-types.ts'
  * `ctx.codeRuntime.language` in this table when assembling the `tools:sdk`
  * section under a non-native mode; a runtime whose language is not a key
  * fails the assembly loudly (same idiom as `toolOrder` violations). Adding a
- * new backend language is a table entry plus its renderer, nothing else.
+ * new backend language is two table entries — a renderer here and a
+ * {@link RUN_CODE_FLAVORS} entry for its `run_code` schema strings — plus the
+ * renderer itself.
  */
 const SDK_RENDERERS: Record<string, (schemas: ToolSdkSchema[]) => string> = {
   typescript: renderToolsSdk,
@@ -604,8 +606,9 @@ export interface Config {
   /**
    * Model presentation. `native` (default) sends every visible schema; `code`
    * sends only `run_code` plus a generated SDK prompt; `both` sends both forms.
-   * Code modes require a TypeScript runtime and fail prompt assembly when it is
-   * absent or mismatched. Under `code`, native names in `toolOrder` are invalid.
+   * Code modes require a `ctx.codeRuntime` whose `language` has a registered
+   * SDK renderer (TypeScript or Python) and fail prompt assembly when it is
+   * absent or has no renderer. Under `code`, native names in `toolOrder` are invalid.
    */
   mode?: ToolPresentationMode
   /**

packages/core/tools/src/py-types.ts

@@ -154,7 +154,14 @@ function pyScalar(value: JsonSchemaScalar): string {
   return String(value)
 }
 
-/** Render a validated scalar `const`/`enum` as `Literal[...]`, falling back to the broad type. */
+/**
+ * Render a validated scalar `const`/`enum` as `Literal[...]`, falling back to
+ * the broad type. Deliberately deviates from PEP 586, which restricts `Literal`
+ * parameters to int/bool/str/bytes/enum/None: a number `const`/`enum` emits a
+ * float literal (`Literal[1.5]`) a strict checker would reject. Harmless here —
+ * the stub is advisory prompt text, only required to parse — and keeping the
+ * exact value communicates the constraint to the model.
+ */
 function renderConstrainedScalar(node: Record<string, unknown>, broad: string, state: RenderState): string {
   if (Object.hasOwn(node, 'const')) {
     state.typing.add('Literal')