fix flaky test

src/service.zig

@@ -5320,8 +5320,18 @@ test "recheck floor: once the interval has passed, the symbol is asked again" {
     var store = svc.store();
     const spec = DataService.dividendTtl(divs[0..]);
 
-    // One second inside the interval -> still served.
-    writeAged(Dividend, &store, "TEST", divs[0..], spec, DataService.smart_refresh_recheck_interval - 1);
+    // A MINUTE either side, not a second. `writeAged` stamps `expires` off
+    // the wall clock at write time and `askedRecently` recovers the age off
+    // the wall clock at read time, so the entry ages by however long the gap
+    // between the two takes. At one second that gap was the margin: under
+    // kcov the instrumented binary occasionally crossed a second boundary,
+    // the "inside" entry read as 12h old, the refetch went ahead, and the
+    // network assertion panicked the coverage run. A minute is far beyond
+    // any real gap and still nothing against a 12-hour interval.
+    const margin: i64 = 60;
+
+    // Inside the interval -> still served.
+    writeAged(Dividend, &store, "TEST", divs[0..], spec, DataService.smart_refresh_recheck_interval - margin);
     {
         svc.panic_on_network_attempt = true;
         const held = try svc.getDividends("TEST", .{});
@@ -5330,9 +5340,9 @@ test "recheck floor: once the interval has passed, the symbol is asked again" {
         svc.panic_on_network_attempt = false;
     }
 
-    // One second past it -> asked again (NoApiKey proves we got to the
-    // provider rather than being served the cache).
-    writeAged(Dividend, &store, "TEST", divs[0..], spec, DataService.smart_refresh_recheck_interval + 1);
+    // Past it -> asked again (NoApiKey proves we got to the provider rather
+    // than being served the cache).
+    writeAged(Dividend, &store, "TEST", divs[0..], spec, DataService.smart_refresh_recheck_interval + margin);
     try std.testing.expectError(DataError.NoApiKey, svc.getDividends("TEST", .{}));
 }