feat(javascript): report observed export property presence (#1160)

* feat(javascript): report observed export property presence

Extend compare_javascript_export_shapes so each retained return variant
lists observed property names and each change reports presence independently
of value resolution. Complete parent coverage classifies one-sided names as
added or removed even when static values stay unknown.

Fixes #725

* test(javascript): match unknown export-shape values by availability

Nested availability objects include a reason when values stay unresolved.
Assert availability through objectContaining so presence-only added and
removed rows still verify unknown values.

* fix(javascript): preserve uncertain export property presence and locations

* fix(javascript): normalize presence and preserve local property coverage

* fix(javascript): require present discriminants for return pairing

* fix(javascript): normalize retained shapes before comparison

* refactor(javascript): share return projection with executable examples

* fix(javascript): localize uncertainty for missing mutated slots

* fix(javascript): bind advertised export examples to exact artifacts

* fix(javascript): keep uncertain property flow as candidates

---------

Co-authored-by: morluto <76467478+morluto@users.noreply.github.com>

src/domain/javascript/javascriptExportShapeComparisonSchemas.test.ts

@@ -1,6 +1,9 @@
 import { expect, it } from "vitest";
 
-import { projectedExportReturnShapesSchema } from "./javascriptExportShapeComparisonSchemas.js";
+import {
+  javaScriptExportShapeComparisonChangeSchema,
+  projectedExportReturnShapesSchema,
+} from "./javascriptExportShapeComparisonSchemas.js";
 
 const projectionWithField = (field: unknown) => ({
   semantic_role: "export-return-shapes",
@@ -29,6 +32,40 @@ const projectionWithField = (field: unknown) => ({
   },
 });
 
+it("rejects a comparison change object missing presence", () => {
+  const digest = "a".repeat(64);
+  const change = {
+    change_id: `jesc_change_${digest}`,
+    status: "added",
+    path: "/total",
+    discriminant: { path: "/kind", value: "results" },
+    left: { availability: "absent" },
+    right: {
+      availability: "unknown",
+      reason: "Static field value is unknown.",
+    },
+    left_source_range: {
+      start: { line: 4, column: 9 },
+      end: { line: 4, column: 48 },
+    },
+    right_source_range: {
+      start: { line: 4, column: 9 },
+      end: { line: 4, column: 62 },
+    },
+    evidence_links: [`ev_${digest}`, `ev_${"b".repeat(64)}`],
+    limitations: [],
+  };
+  expect(
+    javaScriptExportShapeComparisonChangeSchema.safeParse(change).success,
+  ).toBe(false);
+  expect(
+    javaScriptExportShapeComparisonChangeSchema.safeParse({
+      ...change,
+      presence: { left: "absent", right: "present" },
+    }).success,
+  ).toBe(true);
+});
+
 it("parses projected fields into literal, union, or unknown values", () => {
   expect(
     projectedExportReturnShapesSchema.safeParse(