refactor(javascript): group domain semantics and contracts (#907)

src/domain/javascript/javascriptSemanticCoverage.ts

@@ -0,0 +1,36 @@
+/** Exact retention state for one callable's direct returns. */
+export type JavaScriptSemanticReturnCoverage = {
+  readonly retainedCount: number;
+} & {
+  readonly status: "complete" | "partial";
+  readonly omittedCount: 0 | null;
+};
+
+/** Coverage state for one semantic recovery pass. */
+export type JavaScriptSemanticCoverage =
+  | {
+      readonly status: "complete" | "partial";
+      readonly omittedCount: 0;
+    }
+  | {
+      readonly status: "failed";
+      readonly omittedCount: null;
+    };
+
+/** Classify whole-file semantic coverage from parser recovery. */
+export const semanticCoverage = (
+  parserPartial: boolean,
+): JavaScriptSemanticCoverage => ({
+  status: parserPartial ? "partial" : "complete",
+  omittedCount: 0,
+});
+
+/** Classify one callable's direct-return coverage. */
+export const semanticReturnCoverage = (
+  retainedCount: number,
+  parserPartial: boolean,
+): JavaScriptSemanticReturnCoverage => ({
+  status: parserPartial ? "partial" : "complete",
+  retainedCount,
+  omittedCount: 0,
+});