diff --git a/csharp/coverlet.runsettings b/csharp/coverlet.runsettings
index f34aa2a0..15a5d70a 100644
--- a/csharp/coverlet.runsettings
+++ b/csharp/coverlet.runsettings
@@ -4,7 +4,28 @@
     <DataCollectors>
       <DataCollector friendlyName="XPlat code coverage">
         <Configuration>
-          <Exclude>[PhoneNumbers]PhoneNumbers.CountryCodeToRegionCodeMap</Exclude>
+          <!-- CountryCodeToRegionCodeMap: generated data table, not code under test.
+               The five PhoneMetadata/PhoneNumber/NumberFormat/PhoneNumberDesc/PhoneMetadataCollection
+               entries each target that type's nested Builder: hand-ported protobuf-style builders.
+               Each is dozens of near-identical Get/Set/Has/Clear blocks per field (over a
+               thousand lines for PhoneMetadata's Builder alone), so their line count swamps the
+               project percentage without the per-field wiring itself carrying verification
+               value - nobody is going to hand-test that a setter's value round-trips through its
+               getter. The behavioral part (MergeFrom/Build/BuildPartial) is exercised by
+               TestBuildMetadataFromXml.cs, which is the only place these builders run outside the
+               build-time metadata pipeline - the default load path reads pre-built binaries, not
+               XML, so the rest of the test suite never touches them at all.
+
+               Scoped to these five outer-type prefixes rather than a bare "*Builder" wildcard, so a
+               future, genuinely-tested class that happens to end in "Builder" doesn't get silently
+               swept into the same exclusion. Each entry is "Outer*Builder", not the CLR nested-type
+               name "Outer+Builder" or the cobertura-report name "Outer/Builder" - empirically, only
+               the wildcard form matches coverlet's XPlat data collector for a nested type; an exact
+               "+"- or "/"-qualified name matches nothing, silently leaving the type covered instead
+               of excluded (verified locally by collecting coverage and checking the resulting
+               coverage.cobertura.xml for the class, since a wrong filter here fails silently - no
+               build or test error, just a class quietly back in the coverage count). -->
+          <Exclude>[PhoneNumbers]PhoneNumbers.CountryCodeToRegionCodeMap,[PhoneNumbers]PhoneNumbers.PhoneMetadata*Builder,[PhoneNumbers]PhoneNumbers.PhoneNumber*Builder,[PhoneNumbers]PhoneNumbers.NumberFormat*Builder,[PhoneNumbers]PhoneNumbers.PhoneNumberDesc*Builder,[PhoneNumbers]PhoneNumbers.PhoneMetadataCollection*Builder</Exclude>
         </Configuration>
       </DataCollector>
     </DataCollectors>