fix(jobnet-search): degrade a null publicationDate to a null date instead of crashing the search (#418) (#419)

date: job.publicationDate.slice(0, 10) trusted a TypeScript interface
claim nothing validates at runtime: apiFetch casts the JSON body, so one
ad with a null publication date threw TypeError inside the jobAds map
and the whole search exited 1 as API_ERROR. The neighboring
applicationDeadline field was already null-guarded with a 1900-01-01
sentinel. publicationDate is now typed nullable so the compiler enforces
the guard, and the ad degrades per-item to date: null. New test verified
to fail on the unfixed code with the exact production TypeError.

.agents/skills/jobnet-search/cli/tests/search-normalization.test.ts

@@ -161,3 +161,23 @@ describe("Jobnet search normalization", () => {
     expect(output.results[1].deadline).toBe("2026-08-01");
   });
 });
+
+describe("Jobnet null publicationDate degradation", () => {
+  // publicationDate: string was a TypeScript claim, not runtime validation -
+  // apiFetch casts the JSON body, so one ad with a null publication date
+  // threw TypeError from .slice() inside the jobAds map and killed the whole
+  // search as API_ERROR (#418). The neighboring applicationDeadline field is
+  // already guarded (null check + 1900-01-01 sentinel); this pins the same
+  // per-item degradation for publicationDate: date null, no throw.
+  test("an ad with a null publicationDate yields date: null instead of crashing the search", () => {
+    const data = apiResponse();
+    data.jobAds[0].publicationDate = null;
+
+    // The shared fixture flags carry limit: 1, which would slice off the
+    // second ad; lift the limit so the survives-alongside assertion is real.
+    const output = createSearchOutput(data, { ...flags, limit: undefined });
+
+    expect(output.results[0].date).toBeNull();
+    expect(output.results[1].date).toBe("2026-07-02");
+  });
+});