feat(hosts): driver diagnostics channel on /hosts, S7 negotiated PDU size first (#640)

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
2026-10-08 16:57:38 -04:00
parent a8b07ae12d
commit c2bdb7d5de
23 changed files with 469 additions and 20 deletions
@@ -272,6 +272,24 @@ public sealed class HostsDriverViewTests
        row.SkippedTags!.SkippedCount.ShouldBe(20);
    }

+    /// <summary>#640: diagnostics ride the snapshot onto the row, ordered by key; none renders nothing.</summary>
+    [Fact]
+    public void Diagnostics_reach_the_row_ordered_and_absent_diagnostics_yield_no_items()
+    {
+        var with = Snap("MAIN", "s7-a") with
+        {
+            Diagnostics = new Dictionary<string, string> { ["Z"] = "2", ["S7.NegotiatedPduSize"] = "480" },
+        };
+        var without = Snap("MAIN", "s7-b");
+
+        var rows = HostsDriverView.Build([with, without], nodes: null, instances: null).Single().Drivers;
+
+        var a = rows.Single(r => r.DriverInstanceId == "s7-a");
+        a.DiagnosticItems.Select(k => k.Key).ShouldBe(["S7.NegotiatedPduSize", "Z"]);
+        a.DiagnosticItems[0].Value.ShouldBe("480");
+        rows.Single(r => r.DriverInstanceId == "s7-b").DiagnosticItems.ShouldBeEmpty();
+    }
+
    /// <summary>
    ///     A truncated sample must SAY it is truncated. Without the note a capped list reads as the whole
    ///     list, and an operator who fixes the twenty named tags believes the job is done.