diff --git a/wire-runtime-swift/src/main/swift/ProtoCodable/ProtoIntCodable.swift b/wire-runtime-swift/src/main/swift/ProtoCodable/ProtoIntCodable.swift
index afe853c442..62ef82aee8 100644
--- a/wire-runtime-swift/src/main/swift/ProtoCodable/ProtoIntCodable.swift
+++ b/wire-runtime-swift/src/main/swift/ProtoCodable/ProtoIntCodable.swift
@@ -52,3 +52,6 @@ public enum ProtoIntEncoding {
     case signed
     case variable
 }
+
+extension ProtoIntEncoding : Sendable {
+}
diff --git a/wire-runtime-swift/src/test/swift/ExtensibleTests.swift b/wire-runtime-swift/src/test/swift/ExtensibleTests.swift
index a6f22140fe..a84f5c12f5 100644
--- a/wire-runtime-swift/src/test/swift/ExtensibleTests.swift
+++ b/wire-runtime-swift/src/test/swift/ExtensibleTests.swift
@@ -133,4 +133,35 @@ final class ExtensibleTests: XCTestCase {
         XCTAssertEqual(LargeExtensible.default_ext_value17, "my extension default value")
         XCTAssertEqual(LargeExtensible.default_ext_value18, "")
     }
+
+    func testExtensionFieldNumberAndEncodingConstants() {
+        XCTAssertEqual(Extensible.fieldNumber_ext_int32, 1001)
+        XCTAssertEqual(Extensible.fieldEncoding_ext_int32, .variable)
+        XCTAssertEqual(Extensible.fieldNumber_ext_sint32, 1003)
+        XCTAssertEqual(Extensible.fieldEncoding_ext_sint32, .signed)
+        XCTAssertEqual(Extensible.fieldNumber_ext_fixed32, 1004)
+        XCTAssertEqual(Extensible.fieldEncoding_ext_fixed32, .fixed)
+        XCTAssertEqual(Extensible.fieldNumber_ext_string, 1014)
+        XCTAssertEqual(LargeExtensible.fieldNumber_ext_value17, 17)
+        XCTAssertEqual(LargeExtensible.fieldNumber_rep_ext_sint32, 21)
+        XCTAssertEqual(LargeExtensible.fieldEncoding_rep_ext_sint32, .signed)
+
+        // Round-trip a value through the raw APIs using only generated constants.
+        var message = Extensible()
+        message.setUnknownField(
+            fieldNumber: Extensible.fieldNumber_ext_sint32,
+            newValue: Int32(-42),
+            encoding: Extensible.fieldEncoding_ext_sint32
+        )
+        XCTAssertEqual(
+            message.parseUnknownField(
+                fieldNumber: Extensible.fieldNumber_ext_sint32,
+                type: Int32.self,
+                encoding: Extensible.fieldEncoding_ext_sint32
+            ),
+            -42
+        )
+        // The generated accessor reads the same field the raw APIs just wrote.
+        XCTAssertEqual(message.ext_sint32, -42)
+    }
 }
diff --git a/wire-swift-generator/src/main/java/com/squareup/wire/swift/SwiftGenerator.kt b/wire-swift-generator/src/main/java/com/squareup/wire/swift/SwiftGenerator.kt
index 45a6cb6cdf..a22d5c3401 100644
--- a/wire-swift-generator/src/main/java/com/squareup/wire/swift/SwiftGenerator.kt
+++ b/wire-swift-generator/src/main/java/com/squareup/wire/swift/SwiftGenerator.kt
@@ -93,6 +93,7 @@ class SwiftGenerator private constructor(
   private val unknownFields = DeclaredTypeName.typeName("Wire.UnknownFields")
   private val extensibleUnknownFields = DeclaredTypeName.typeName("Wire.ExtensibleUnknownFields")
   private val protoExtensible = DeclaredTypeName.typeName("Wire.ProtoExtensible")
+  private val protoIntEncoding = DeclaredTypeName.typeName("Wire.ProtoIntEncoding")
 
   private val stringLiteralCodingKeys = DeclaredTypeName.typeName("Wire.StringLiteralCodingKeys")
 
@@ -1328,6 +1329,9 @@ class SwiftGenerator private constructor(
 
               addProperty(defaultProperty)
             }
+
+            addProperty(extensionFieldNumberProperty(field))
+            extensionFieldEncodingProperty(field)?.let { addProperty(it) }
           }
         }
         .build()
@@ -1337,6 +1341,23 @@ class SwiftGenerator private constructor(
     }
   }
 
+  private fun extensionFieldNumberProperty(field: Field): PropertySpec = PropertySpec.varBuilder("fieldNumber_${field.safeName}", UINT32, PUBLIC, STATIC)
+    .addDoc("Field number for the %L extension field.\n", field.safeName)
+    .mutable(false)
+    .initializer("%L", field.tag)
+    .build()
+
+  // Emitted whenever the accessor passes `encoding:` to parseUnknownField/setUnknownField, so
+  // callers of those APIs can source the (fieldNumber, encoding) pair entirely from codegen.
+  private fun extensionFieldEncodingProperty(field: Field): PropertySpec? {
+    val encoding = field.type!!.encoding ?: return null
+    return PropertySpec.varBuilder("fieldEncoding_${field.safeName}", protoIntEncoding, PUBLIC, STATIC)
+      .addDoc("Integer encoding for the %L extension field.\n", field.safeName)
+      .mutable(false)
+      .initializer(".%N", encoding)
+      .build()
+  }
+
   private fun generateMessageExtensions(
     type: MessageType,
     structType: DeclaredTypeName,
@@ -1416,6 +1437,12 @@ class SwiftGenerator private constructor(
 
               addProperty(defaultProperty)
             }
+
+            // The constants belong on the extended type; the storage pass must skip them or they'd be declared twice.
+            if (!forStorageType) {
+              addProperty(extensionFieldNumberProperty(field))
+              extensionFieldEncodingProperty(field)?.let { addProperty(it) }
+            }
           }
         }
         .build()
diff --git a/wire-swift-generator/src/test/java/com/squareup/wire/swift/SwiftGeneratorTest.kt b/wire-swift-generator/src/test/java/com/squareup/wire/swift/SwiftGeneratorTest.kt
index ffbda72d89..56c0006834 100644
--- a/wire-swift-generator/src/test/java/com/squareup/wire/swift/SwiftGeneratorTest.kt
+++ b/wire-swift-generator/src/test/java/com/squareup/wire/swift/SwiftGeneratorTest.kt
@@ -18,6 +18,7 @@ package com.squareup.wire.swift
 import assertk.assertThat
 import assertk.assertions.contains
 import assertk.assertions.doesNotContain
+import assertk.assertions.isEqualTo
 import com.squareup.wire.buildSchema
 import com.squareup.wire.schema.Schema
 import io.outfoxx.swiftpoet.FileSpec
@@ -64,6 +65,119 @@ class SwiftGeneratorTest {
     assertThat(code).contains("self.parseUnknownField(fieldNumber: 50003)")
   }
 
+  @Test fun extensionFieldNumbersAreExposedAsConstants() {
+    val schema = buildSchema {
+      add(
+        "custom_options.proto".toPath(),
+        """
+        |syntax = "proto3";
+        |
+        |package squareup.protos3.kotlin.custom_options;
+        |
+        |import "google/protobuf/descriptor.proto";
+        |
+        |extend google.protobuf.MessageOptions {
+        |  string implicit_scalar = 50001;
+        |  repeated string repeated_scalar = 50003;
+        |}
+        """.trimMargin(),
+      )
+    }
+
+    val code = schema.generateSwift("google.protobuf.MessageOptions")
+
+    assertThat(code).contains("public static let fieldNumber_implicit_scalar: UInt32 = 50001")
+    assertThat(code).contains("public static let fieldNumber_repeated_scalar: UInt32 = 50003")
+  }
+
+  @Test fun extensionFieldEncodingsAreExposedAsConstants() {
+    val schema = buildSchema {
+      add(
+        "extensible_message.proto".toPath(),
+        """
+        |syntax = "proto2";
+        |
+        |package squareup.protos2.kotlin;
+        |
+        |message ExtensibleMessage {
+        |  extensions 100 to 200;
+        |}
+        |
+        |extend ExtensibleMessage {
+        |  optional int32 ext_int32 = 100;
+        |  optional sint32 ext_sint32 = 101;
+        |  optional fixed32 ext_fixed32 = 102;
+        |  repeated sint64 rep_ext_sint64 = 103;
+        |  optional string ext_string = 104;
+        |}
+        """.trimMargin(),
+      )
+    }
+
+    val code = schema.generateSwift("squareup.protos2.kotlin.ExtensibleMessage")
+
+    assertThat(code).contains("public static let fieldEncoding_ext_int32: ProtoIntEncoding = .variable")
+    assertThat(code).contains("public static let fieldEncoding_ext_sint32: ProtoIntEncoding = .signed")
+    assertThat(code).contains("public static let fieldEncoding_ext_fixed32: ProtoIntEncoding = .fixed")
+    assertThat(code).contains("public static let fieldEncoding_rep_ext_sint64: ProtoIntEncoding = .signed")
+    // Only integer fields take an explicit encoding in parseUnknownField/setUnknownField.
+    assertThat(code).doesNotContain("fieldEncoding_ext_string")
+  }
+
+  @Test fun extensionFieldNumberConstantsAreGeneratedOnceForHeapAllocatedMessages() {
+    val schema = buildSchema {
+      add(
+        "big_message.proto".toPath(),
+        """
+        |syntax = "proto2";
+        |
+        |package squareup.protos2.kotlin;
+        |
+        |message BigMessage {
+        |  optional int32 f1 = 1;
+        |  optional int32 f2 = 2;
+        |  optional int32 f3 = 3;
+        |  optional int32 f4 = 4;
+        |  optional int32 f5 = 5;
+        |  optional int32 f6 = 6;
+        |  optional int32 f7 = 7;
+        |  optional int32 f8 = 8;
+        |  optional int32 f9 = 9;
+        |  optional int32 f10 = 10;
+        |  optional int32 f11 = 11;
+        |  optional int32 f12 = 12;
+        |  optional int32 f13 = 13;
+        |  optional int32 f14 = 14;
+        |  optional int32 f15 = 15;
+        |  optional int32 f16 = 16;
+        |
+        |  extensions 1000 to 1999;
+        |}
+        |
+        |extend BigMessage {
+        |  optional string extra = 1000;
+        |  optional sint32 extra_signed = 1001;
+        |}
+        """.trimMargin(),
+      )
+    }
+
+    val code = schema.generateSwift("squareup.protos2.kotlin.BigMessage")
+
+    // Precondition: the message must actually be heap-allocated, or the single-emission
+    // assertion below passes trivially because only one extension block is generated at all.
+    assertThat(code).contains("public struct Storage")
+
+    val constant = "public static let fieldNumber_extra: UInt32 = 1000"
+    assertThat(code).contains(constant)
+    // The constant belongs on the extended type only, not on its CopyOnWrite storage type.
+    assertThat(code.indexOf(constant)).isEqualTo(code.lastIndexOf(constant))
+
+    val encodingConstant = "public static let fieldEncoding_extra_signed: ProtoIntEncoding = .signed"
+    assertThat(code).contains(encodingConstant)
+    assertThat(code.indexOf(encodingConstant)).isEqualTo(code.lastIndexOf(encodingConstant))
+  }
+
   @Test fun usesFieldMask() {
     val schema = buildSchema {
       add(
diff --git a/wire-tests-swift/manifest/module_one/SwiftModuleOneMessage.swift b/wire-tests-swift/manifest/module_one/SwiftModuleOneMessage.swift
index 37cecfe690..72c0afe4c6 100644
--- a/wire-tests-swift/manifest/module_one/SwiftModuleOneMessage.swift
+++ b/wire-tests-swift/manifest/module_one/SwiftModuleOneMessage.swift
@@ -38,6 +38,10 @@ extension SwiftModuleOneMessage {
      * Default value for extension_message extension field.
      */
     public static let default_extension_message: ExtensionMessage = .defaultedValue
+    /**
+     * Field number for the extension_message extension field.
+     */
+    public static let fieldNumber_extension_message: UInt32 = 1000
 }
 
 #if !WIRE_REMOVE_EQUATABLE
diff --git a/wire-tests-swift/no-manifest/src/main/swift/AllTypes.swift b/wire-tests-swift/no-manifest/src/main/swift/AllTypes.swift
index f9fb25df59..a5cefed926 100644
--- a/wire-tests-swift/no-manifest/src/main/swift/AllTypes.swift
+++ b/wire-tests-swift/no-manifest/src/main/swift/AllTypes.swift
@@ -1284,6 +1284,14 @@ extension AllTypes : ProtoExtensible {
      * Default value for ext_opt_int32 extension field.
      */
     public static let default_ext_opt_int32: Int32 = .defaultedValue
+    /**
+     * Field number for the ext_opt_int32 extension field.
+     */
+    public static let fieldNumber_ext_opt_int32: UInt32 = 1001
+    /**
+     * Integer encoding for the ext_opt_int32 extension field.
+     */
+    public static let fieldEncoding_ext_opt_int32: ProtoIntEncoding = .variable
     /**
      *
      * Source: all_types.proto
@@ -1300,6 +1308,14 @@ extension AllTypes : ProtoExtensible {
      * Default value for ext_opt_uint32 extension field.
      */
     public static let default_ext_opt_uint32: UInt32 = .defaultedValue
+    /**
+     * Field number for the ext_opt_uint32 extension field.
+     */
+    public static let fieldNumber_ext_opt_uint32: UInt32 = 1002
+    /**
+     * Integer encoding for the ext_opt_uint32 extension field.
+     */
+    public static let fieldEncoding_ext_opt_uint32: ProtoIntEncoding = .variable
     /**
      *
      * Source: all_types.proto
@@ -1316,6 +1332,14 @@ extension AllTypes : ProtoExtensible {
      * Default value for ext_opt_sint32 extension field.
      */
     public static let default_ext_opt_sint32: Int32 = .defaultedValue
+    /**
+     * Field number for the ext_opt_sint32 extension field.
+     */
+    public static let fieldNumber_ext_opt_sint32: UInt32 = 1003
+    /**
+     * Integer encoding for the ext_opt_sint32 extension field.
+     */
+    public static let fieldEncoding_ext_opt_sint32: ProtoIntEncoding = .signed
     /**
      *
      * Source: all_types.proto
@@ -1332,6 +1356,14 @@ extension AllTypes : ProtoExtensible {
      * Default value for ext_opt_fixed32 extension field.
      */
     public static let default_ext_opt_fixed32: UInt32 = .defaultedValue
+    /**
+     * Field number for the ext_opt_fixed32 extension field.
+     */
+    public static let fieldNumber_ext_opt_fixed32: UInt32 = 1004
+    /**
+     * Integer encoding for the ext_opt_fixed32 extension field.
+     */
+    public static let fieldEncoding_ext_opt_fixed32: ProtoIntEncoding = .fixed
     /**
      *
      * Source: all_types.proto
@@ -1348,6 +1380,14 @@ extension AllTypes : ProtoExtensible {
      * Default value for ext_opt_sfixed32 extension field.
      */
     public static let default_ext_opt_sfixed32: Int32 = .defaultedValue
+    /**
+     * Field number for the ext_opt_sfixed32 extension field.
+     */
+    public static let fieldNumber_ext_opt_sfixed32: UInt32 = 1005
+    /**
+     * Integer encoding for the ext_opt_sfixed32 extension field.
+     */
+    public static let fieldEncoding_ext_opt_sfixed32: ProtoIntEncoding = .fixed
     /**
      *
      * Source: all_types.proto
@@ -1364,6 +1404,14 @@ extension AllTypes : ProtoExtensible {
      * Default value for ext_opt_int64 extension field.
      */
     public static let default_ext_opt_int64: Int64 = .defaultedValue
+    /**
+     * Field number for the ext_opt_int64 extension field.
+     */
+    public static let fieldNumber_ext_opt_int64: UInt32 = 1006
+    /**
+     * Integer encoding for the ext_opt_int64 extension field.
+     */
+    public static let fieldEncoding_ext_opt_int64: ProtoIntEncoding = .variable
     /**
      *
      * Source: all_types.proto
@@ -1380,6 +1428,14 @@ extension AllTypes : ProtoExtensible {
      * Default value for ext_opt_uint64 extension field.
      */
     public static let default_ext_opt_uint64: UInt64 = .defaultedValue
+    /**
+     * Field number for the ext_opt_uint64 extension field.
+     */
+    public static let fieldNumber_ext_opt_uint64: UInt32 = 1007
+    /**
+     * Integer encoding for the ext_opt_uint64 extension field.
+     */
+    public static let fieldEncoding_ext_opt_uint64: ProtoIntEncoding = .variable
     /**
      *
      * Source: all_types.proto
@@ -1396,6 +1452,14 @@ extension AllTypes : ProtoExtensible {
      * Default value for ext_opt_sint64 extension field.
      */
     public static let default_ext_opt_sint64: Int64 = .defaultedValue
+    /**
+     * Field number for the ext_opt_sint64 extension field.
+     */
+    public static let fieldNumber_ext_opt_sint64: UInt32 = 1008
+    /**
+     * Integer encoding for the ext_opt_sint64 extension field.
+     */
+    public static let fieldEncoding_ext_opt_sint64: ProtoIntEncoding = .signed
     /**
      *
      * Source: all_types.proto
@@ -1412,6 +1476,14 @@ extension AllTypes : ProtoExtensible {
      * Default value for ext_opt_fixed64 extension field.
      */
     public static let default_ext_opt_fixed64: UInt64 = .defaultedValue
+    /**
+     * Field number for the ext_opt_fixed64 extension field.
+     */
+    public static let fieldNumber_ext_opt_fixed64: UInt32 = 1009
+    /**
+     * Integer encoding for the ext_opt_fixed64 extension field.
+     */
+    public static let fieldEncoding_ext_opt_fixed64: ProtoIntEncoding = .fixed
     /**
      *
      * Source: all_types.proto
@@ -1428,6 +1500,14 @@ extension AllTypes : ProtoExtensible {
      * Default value for ext_opt_sfixed64 extension field.
      */
     public static let default_ext_opt_sfixed64: Int64 = .defaultedValue
+    /**
+     * Field number for the ext_opt_sfixed64 extension field.
+     */
+    public static let fieldNumber_ext_opt_sfixed64: UInt32 = 1010
+    /**
+     * Integer encoding for the ext_opt_sfixed64 extension field.
+     */
+    public static let fieldEncoding_ext_opt_sfixed64: ProtoIntEncoding = .fixed
     /**
      *
      * Source: all_types.proto
@@ -1444,6 +1524,10 @@ extension AllTypes : ProtoExtensible {
      * Default value for ext_opt_bool extension field.
      */
     public static let default_ext_opt_bool: Bool = .defaultedValue
+    /**
+     * Field number for the ext_opt_bool extension field.
+     */
+    public static let fieldNumber_ext_opt_bool: UInt32 = 1011
     /**
      *
      * Source: all_types.proto
@@ -1460,6 +1544,10 @@ extension AllTypes : ProtoExtensible {
      * Default value for ext_opt_float extension field.
      */
     public static let default_ext_opt_float: Float = .defaultedValue
+    /**
+     * Field number for the ext_opt_float extension field.
+     */
+    public static let fieldNumber_ext_opt_float: UInt32 = 1012
     /**
      *
      * Source: all_types.proto
@@ -1476,6 +1564,10 @@ extension AllTypes : ProtoExtensible {
      * Default value for ext_opt_double extension field.
      */
     public static let default_ext_opt_double: Double = .defaultedValue
+    /**
+     * Field number for the ext_opt_double extension field.
+     */
+    public static let fieldNumber_ext_opt_double: UInt32 = 1013
     /**
      *
      * Source: all_types.proto
@@ -1492,6 +1584,10 @@ extension AllTypes : ProtoExtensible {
      * Default value for ext_opt_string extension field.
      */
     public static let default_ext_opt_string: String = .defaultedValue
+    /**
+     * Field number for the ext_opt_string extension field.
+     */
+    public static let fieldNumber_ext_opt_string: UInt32 = 1014
     /**
      *
      * Source: all_types.proto
@@ -1508,6 +1604,10 @@ extension AllTypes : ProtoExtensible {
      * Default value for ext_opt_bytes extension field.
      */
     public static let default_ext_opt_bytes: Foundation.Data = .defaultedValue
+    /**
+     * Field number for the ext_opt_bytes extension field.
+     */
+    public static let fieldNumber_ext_opt_bytes: UInt32 = 1015
     /**
      *
      * Source: all_types.proto
@@ -1520,6 +1620,10 @@ extension AllTypes : ProtoExtensible {
             storage.ext_opt_nested_enum = newValue
         }
     }
+    /**
+     * Field number for the ext_opt_nested_enum extension field.
+     */
+    public static let fieldNumber_ext_opt_nested_enum: UInt32 = 1016
     /**
      *
      * Source: all_types.proto
@@ -1536,6 +1640,10 @@ extension AllTypes : ProtoExtensible {
      * Default value for ext_opt_nested_message extension field.
      */
     public static let default_ext_opt_nested_message: AllTypes.NestedMessage = .defaultedValue
+    /**
+     * Field number for the ext_opt_nested_message extension field.
+     */
+    public static let fieldNumber_ext_opt_nested_message: UInt32 = 1017
     /**
      *
      * Source: all_types.proto
@@ -1548,6 +1656,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_rep_int32 = newValue
         }
     }
+    /**
+     * Field number for the ext_rep_int32 extension field.
+     */
+    public static let fieldNumber_ext_rep_int32: UInt32 = 1101
+    /**
+     * Integer encoding for the ext_rep_int32 extension field.
+     */
+    public static let fieldEncoding_ext_rep_int32: ProtoIntEncoding = .variable
     /**
      *
      * Source: all_types.proto
@@ -1560,6 +1676,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_rep_uint32 = newValue
         }
     }
+    /**
+     * Field number for the ext_rep_uint32 extension field.
+     */
+    public static let fieldNumber_ext_rep_uint32: UInt32 = 1102
+    /**
+     * Integer encoding for the ext_rep_uint32 extension field.
+     */
+    public static let fieldEncoding_ext_rep_uint32: ProtoIntEncoding = .variable
     /**
      *
      * Source: all_types.proto
@@ -1572,6 +1696,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_rep_sint32 = newValue
         }
     }
+    /**
+     * Field number for the ext_rep_sint32 extension field.
+     */
+    public static let fieldNumber_ext_rep_sint32: UInt32 = 1103
+    /**
+     * Integer encoding for the ext_rep_sint32 extension field.
+     */
+    public static let fieldEncoding_ext_rep_sint32: ProtoIntEncoding = .signed
     /**
      *
      * Source: all_types.proto
@@ -1584,6 +1716,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_rep_fixed32 = newValue
         }
     }
+    /**
+     * Field number for the ext_rep_fixed32 extension field.
+     */
+    public static let fieldNumber_ext_rep_fixed32: UInt32 = 1104
+    /**
+     * Integer encoding for the ext_rep_fixed32 extension field.
+     */
+    public static let fieldEncoding_ext_rep_fixed32: ProtoIntEncoding = .fixed
     /**
      *
      * Source: all_types.proto
@@ -1596,6 +1736,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_rep_sfixed32 = newValue
         }
     }
+    /**
+     * Field number for the ext_rep_sfixed32 extension field.
+     */
+    public static let fieldNumber_ext_rep_sfixed32: UInt32 = 1105
+    /**
+     * Integer encoding for the ext_rep_sfixed32 extension field.
+     */
+    public static let fieldEncoding_ext_rep_sfixed32: ProtoIntEncoding = .fixed
     /**
      *
      * Source: all_types.proto
@@ -1608,6 +1756,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_rep_int64 = newValue
         }
     }
+    /**
+     * Field number for the ext_rep_int64 extension field.
+     */
+    public static let fieldNumber_ext_rep_int64: UInt32 = 1106
+    /**
+     * Integer encoding for the ext_rep_int64 extension field.
+     */
+    public static let fieldEncoding_ext_rep_int64: ProtoIntEncoding = .variable
     /**
      *
      * Source: all_types.proto
@@ -1620,6 +1776,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_rep_uint64 = newValue
         }
     }
+    /**
+     * Field number for the ext_rep_uint64 extension field.
+     */
+    public static let fieldNumber_ext_rep_uint64: UInt32 = 1107
+    /**
+     * Integer encoding for the ext_rep_uint64 extension field.
+     */
+    public static let fieldEncoding_ext_rep_uint64: ProtoIntEncoding = .variable
     /**
      *
      * Source: all_types.proto
@@ -1632,6 +1796,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_rep_sint64 = newValue
         }
     }
+    /**
+     * Field number for the ext_rep_sint64 extension field.
+     */
+    public static let fieldNumber_ext_rep_sint64: UInt32 = 1108
+    /**
+     * Integer encoding for the ext_rep_sint64 extension field.
+     */
+    public static let fieldEncoding_ext_rep_sint64: ProtoIntEncoding = .signed
     /**
      *
      * Source: all_types.proto
@@ -1644,6 +1816,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_rep_fixed64 = newValue
         }
     }
+    /**
+     * Field number for the ext_rep_fixed64 extension field.
+     */
+    public static let fieldNumber_ext_rep_fixed64: UInt32 = 1109
+    /**
+     * Integer encoding for the ext_rep_fixed64 extension field.
+     */
+    public static let fieldEncoding_ext_rep_fixed64: ProtoIntEncoding = .fixed
     /**
      *
      * Source: all_types.proto
@@ -1656,6 +1836,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_rep_sfixed64 = newValue
         }
     }
+    /**
+     * Field number for the ext_rep_sfixed64 extension field.
+     */
+    public static let fieldNumber_ext_rep_sfixed64: UInt32 = 1110
+    /**
+     * Integer encoding for the ext_rep_sfixed64 extension field.
+     */
+    public static let fieldEncoding_ext_rep_sfixed64: ProtoIntEncoding = .fixed
     /**
      *
      * Source: all_types.proto
@@ -1668,6 +1856,10 @@ extension AllTypes : ProtoExtensible {
             storage.ext_rep_bool = newValue
         }
     }
+    /**
+     * Field number for the ext_rep_bool extension field.
+     */
+    public static let fieldNumber_ext_rep_bool: UInt32 = 1111
     /**
      *
      * Source: all_types.proto
@@ -1680,6 +1872,10 @@ extension AllTypes : ProtoExtensible {
             storage.ext_rep_float = newValue
         }
     }
+    /**
+     * Field number for the ext_rep_float extension field.
+     */
+    public static let fieldNumber_ext_rep_float: UInt32 = 1112
     /**
      *
      * Source: all_types.proto
@@ -1692,6 +1888,10 @@ extension AllTypes : ProtoExtensible {
             storage.ext_rep_double = newValue
         }
     }
+    /**
+     * Field number for the ext_rep_double extension field.
+     */
+    public static let fieldNumber_ext_rep_double: UInt32 = 1113
     /**
      *
      * Source: all_types.proto
@@ -1704,6 +1904,10 @@ extension AllTypes : ProtoExtensible {
             storage.ext_rep_string = newValue
         }
     }
+    /**
+     * Field number for the ext_rep_string extension field.
+     */
+    public static let fieldNumber_ext_rep_string: UInt32 = 1114
     /**
      *
      * Source: all_types.proto
@@ -1716,6 +1920,10 @@ extension AllTypes : ProtoExtensible {
             storage.ext_rep_bytes = newValue
         }
     }
+    /**
+     * Field number for the ext_rep_bytes extension field.
+     */
+    public static let fieldNumber_ext_rep_bytes: UInt32 = 1115
     /**
      *
      * Source: all_types.proto
@@ -1728,6 +1936,10 @@ extension AllTypes : ProtoExtensible {
             storage.ext_rep_nested_enum = newValue
         }
     }
+    /**
+     * Field number for the ext_rep_nested_enum extension field.
+     */
+    public static let fieldNumber_ext_rep_nested_enum: UInt32 = 1116
     /**
      *
      * Source: all_types.proto
@@ -1740,6 +1952,10 @@ extension AllTypes : ProtoExtensible {
             storage.ext_rep_nested_message = newValue
         }
     }
+    /**
+     * Field number for the ext_rep_nested_message extension field.
+     */
+    public static let fieldNumber_ext_rep_nested_message: UInt32 = 1117
     /**
      *
      * Source: all_types.proto
@@ -1752,6 +1968,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_pack_int32 = newValue
         }
     }
+    /**
+     * Field number for the ext_pack_int32 extension field.
+     */
+    public static let fieldNumber_ext_pack_int32: UInt32 = 1201
+    /**
+     * Integer encoding for the ext_pack_int32 extension field.
+     */
+    public static let fieldEncoding_ext_pack_int32: ProtoIntEncoding = .variable
     /**
      *
      * Source: all_types.proto
@@ -1764,6 +1988,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_pack_uint32 = newValue
         }
     }
+    /**
+     * Field number for the ext_pack_uint32 extension field.
+     */
+    public static let fieldNumber_ext_pack_uint32: UInt32 = 1202
+    /**
+     * Integer encoding for the ext_pack_uint32 extension field.
+     */
+    public static let fieldEncoding_ext_pack_uint32: ProtoIntEncoding = .variable
     /**
      *
      * Source: all_types.proto
@@ -1776,6 +2008,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_pack_sint32 = newValue
         }
     }
+    /**
+     * Field number for the ext_pack_sint32 extension field.
+     */
+    public static let fieldNumber_ext_pack_sint32: UInt32 = 1203
+    /**
+     * Integer encoding for the ext_pack_sint32 extension field.
+     */
+    public static let fieldEncoding_ext_pack_sint32: ProtoIntEncoding = .signed
     /**
      *
      * Source: all_types.proto
@@ -1788,6 +2028,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_pack_fixed32 = newValue
         }
     }
+    /**
+     * Field number for the ext_pack_fixed32 extension field.
+     */
+    public static let fieldNumber_ext_pack_fixed32: UInt32 = 1204
+    /**
+     * Integer encoding for the ext_pack_fixed32 extension field.
+     */
+    public static let fieldEncoding_ext_pack_fixed32: ProtoIntEncoding = .fixed
     /**
      *
      * Source: all_types.proto
@@ -1800,6 +2048,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_pack_sfixed32 = newValue
         }
     }
+    /**
+     * Field number for the ext_pack_sfixed32 extension field.
+     */
+    public static let fieldNumber_ext_pack_sfixed32: UInt32 = 1205
+    /**
+     * Integer encoding for the ext_pack_sfixed32 extension field.
+     */
+    public static let fieldEncoding_ext_pack_sfixed32: ProtoIntEncoding = .fixed
     /**
      *
      * Source: all_types.proto
@@ -1812,6 +2068,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_pack_int64 = newValue
         }
     }
+    /**
+     * Field number for the ext_pack_int64 extension field.
+     */
+    public static let fieldNumber_ext_pack_int64: UInt32 = 1206
+    /**
+     * Integer encoding for the ext_pack_int64 extension field.
+     */
+    public static let fieldEncoding_ext_pack_int64: ProtoIntEncoding = .variable
     /**
      *
      * Source: all_types.proto
@@ -1824,6 +2088,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_pack_uint64 = newValue
         }
     }
+    /**
+     * Field number for the ext_pack_uint64 extension field.
+     */
+    public static let fieldNumber_ext_pack_uint64: UInt32 = 1207
+    /**
+     * Integer encoding for the ext_pack_uint64 extension field.
+     */
+    public static let fieldEncoding_ext_pack_uint64: ProtoIntEncoding = .variable
     /**
      *
      * Source: all_types.proto
@@ -1836,6 +2108,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_pack_sint64 = newValue
         }
     }
+    /**
+     * Field number for the ext_pack_sint64 extension field.
+     */
+    public static let fieldNumber_ext_pack_sint64: UInt32 = 1208
+    /**
+     * Integer encoding for the ext_pack_sint64 extension field.
+     */
+    public static let fieldEncoding_ext_pack_sint64: ProtoIntEncoding = .signed
     /**
      *
      * Source: all_types.proto
@@ -1848,6 +2128,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_pack_fixed64 = newValue
         }
     }
+    /**
+     * Field number for the ext_pack_fixed64 extension field.
+     */
+    public static let fieldNumber_ext_pack_fixed64: UInt32 = 1209
+    /**
+     * Integer encoding for the ext_pack_fixed64 extension field.
+     */
+    public static let fieldEncoding_ext_pack_fixed64: ProtoIntEncoding = .fixed
     /**
      *
      * Source: all_types.proto
@@ -1860,6 +2148,14 @@ extension AllTypes : ProtoExtensible {
             storage.ext_pack_sfixed64 = newValue
         }
     }
+    /**
+     * Field number for the ext_pack_sfixed64 extension field.
+     */
+    public static let fieldNumber_ext_pack_sfixed64: UInt32 = 1210
+    /**
+     * Integer encoding for the ext_pack_sfixed64 extension field.
+     */
+    public static let fieldEncoding_ext_pack_sfixed64: ProtoIntEncoding = .fixed
     /**
      *
      * Source: all_types.proto
@@ -1872,6 +2168,10 @@ extension AllTypes : ProtoExtensible {
             storage.ext_pack_bool = newValue
         }
     }
+    /**
+     * Field number for the ext_pack_bool extension field.
+     */
+    public static let fieldNumber_ext_pack_bool: UInt32 = 1211
     /**
      *
      * Source: all_types.proto
@@ -1884,6 +2184,10 @@ extension AllTypes : ProtoExtensible {
             storage.ext_pack_float = newValue
         }
     }
+    /**
+     * Field number for the ext_pack_float extension field.
+     */
+    public static let fieldNumber_ext_pack_float: UInt32 = 1212
     /**
      *
      * Source: all_types.proto
@@ -1896,6 +2200,10 @@ extension AllTypes : ProtoExtensible {
             storage.ext_pack_double = newValue
         }
     }
+    /**
+     * Field number for the ext_pack_double extension field.
+     */
+    public static let fieldNumber_ext_pack_double: UInt32 = 1213
     /**
      *
      * Source: all_types.proto
@@ -1908,6 +2216,10 @@ extension AllTypes : ProtoExtensible {
             storage.ext_pack_nested_enum = newValue
         }
     }
+    /**
+     * Field number for the ext_pack_nested_enum extension field.
+     */
+    public static let fieldNumber_ext_pack_nested_enum: UInt32 = 1216
 }
 
 #if !WIRE_REMOVE_EQUATABLE
diff --git a/wire-tests-swift/no-manifest/src/main/swift/FooBar.swift b/wire-tests-swift/no-manifest/src/main/swift/FooBar.swift
index 61b1ee177e..95efa418f6 100644
--- a/wire-tests-swift/no-manifest/src/main/swift/FooBar.swift
+++ b/wire-tests-swift/no-manifest/src/main/swift/FooBar.swift
@@ -45,6 +45,10 @@ extension FooBar {
             self.setUnknownField(fieldNumber: 101, newValue: newValue)
         }
     }
+    /**
+     * Field number for the ext extension field.
+     */
+    public static let fieldNumber_ext: UInt32 = 101
     /**
      *
      * Source: custom_options.proto
@@ -57,6 +61,10 @@ extension FooBar {
             self.setUnknownField(fieldNumber: 102, newValue: newValue)
         }
     }
+    /**
+     * Field number for the rep extension field.
+     */
+    public static let fieldNumber_rep: UInt32 = 102
     /**
      *
      * Source: custom_options.proto
@@ -73,6 +81,10 @@ extension FooBar {
      * Default value for more_string extension field.
      */
     public static let default_more_string: String = .defaultedValue
+    /**
+     * Field number for the more_string extension field.
+     */
+    public static let fieldNumber_more_string: UInt32 = 150
 }
 
 #if !WIRE_REMOVE_EQUATABLE