refactor(javascript): own coverage facts and reuse block prefixes

Separate syntax, semantic uncertainty, examination limits and observed Electron applicability at the static producer, then preserve them through worker, graph and retained/inline summary views. Derive the established parse_status from the same facts and leave historical measurements unknown. Give semantic resource-limit classifications one schema owner.

Replace repeated block-prefix searches and copies with collector-scoped syntax indexes. Keep invocation environments separate, charge indexing/replay to the existing work budget and yield during prefix work. Remove the superseded synchronous collector entrypoint.

Validated producer, worker, CLI/MCP, historical and partial-coverage regressions, plus actual cancellation during indexing. Bounded authored 128/256-call controls preserved all prior facts while replacing repeated search/copy work with one index pass; this is not a throughput or agent-token benchmark.

src/application/javascript/JavaScriptArtifactGraphStructure.test.ts

@@ -130,6 +130,11 @@ describe("skipped JavaScript parse reporting", () => {
     const context = contextFor(file, analysisFor([skippedEntry(file)]));
     addJavaScriptArtifactFiles(context);
     expect(fileObservation(context).parse_status).toBe("skipped");
+    expect(fileObservation(context).analysis_coverage).toMatchObject({
+      syntax: { status: "not-examined", error_count: null },
+      semantics: { unknown_findings: null },
+      examination: { status: "not-examined" },
+    });
   });
 
   it("keeps parse_status null for a JavaScript file never attempted", () => {
@@ -157,6 +162,21 @@ describe("skipped JavaScript parse reporting", () => {
     const context = contextFor(file, analysisFor([entry]));
     addJavaScriptArtifactFiles(context);
     expect(fileObservation(context).parse_status).toBe(javascript.parse_status);
+    expect(fileObservation(context).analysis_coverage).toEqual(
+      javascript.analysis_coverage,
+    );
+  });
+
+  it("does not reconstruct coverage from a historical overall summary", () => {
+    const file = skippedFile();
+    const { analysis_coverage: _coverage, ...javascript } =
+      analyzeJavaScriptStaticSource(file.text.included ? file.text.value : "");
+    const context = contextFor(
+      file,
+      analysisFor([{ file, javascript, semantic: null }]),
+    );
+    addJavaScriptArtifactFiles(context);
+    expect(fileObservation(context)).not.toHaveProperty("analysis_coverage");
   });
 });