diff --git a/.github/ISSUE_TEMPLATE/BASICFORMAT_BUG.yml b/.github/ISSUE_TEMPLATE/BASICFORMAT_BUG.yml
index a2c8f864f8e..79e609f887f 100644
--- a/.github/ISSUE_TEMPLATE/BASICFORMAT_BUG.yml
+++ b/.github/ISSUE_TEMPLATE/BASICFORMAT_BUG.yml
@@ -2,38 +2,38 @@ name: BasicFormat Bug
 description: A bug in the BasicFormat module
 labels: [bug, BasicFormat]
 body:
- - type: markdown
-   attributes:
-     value: Thanks for taking the time to fill out this bug report! We would really appreciate if you could take the time to reduce the issue as described in [Filing BasicFormat Bug Reports](https://swiftpackageindex.com/swiftlang/swift-syntax/main/documentation/swiftbasicformat/filingbugreports).
- - type: textarea
-   id: source
-   attributes:
-     label: Source Code
-     description: The source code that, when formatted, produces incorrectly formatted code.
-     value: |
-       ```swift
-       ```
- - type: textarea
-   id: source
-   attributes:
-     label: Actual Formatted Code
-     description: The way that `BasicFormat` formats the above code
-     value: |
-       ```swift
-       ```
+  - type: markdown
+    attributes:
+      value: Thanks for taking the time to fill out this bug report! We would really appreciate if you could take the time to reduce the issue as described in [Filing BasicFormat Bug Reports](https://swiftpackageindex.com/swiftlang/swift-syntax/main/documentation/swiftbasicformat/filingbugreports).
   - type: textarea
-   id: source
-   attributes:
-     label: Expected Formatted Code
-     description: The way that you think `BasicFormat` should format the code
-     value: |
-       ```swift
-       ```
- - type: textarea
-   id: description
-   attributes:
-     label: Description
-     description: |
-       Any additional information you can provide for this issue, like
-        - Has this issue started occurring recently?
-        - Is the issue only happening under certain circumstances?
+    id: source
+    attributes:
+      label: Source Code
+      description: The source code that, when formatted, produces incorrectly formatted code.
+      value: |
+        ```swift
+        ```
+  - type: textarea
+    id: source
+    attributes:
+      label: Actual Formatted Code
+      description: The way that `BasicFormat` formats the above code
+      value: |
+        ```swift
+        ```
+  - type: textarea
+    id: source
+    attributes:
+      label: Expected Formatted Code
+      description: The way that you think `BasicFormat` should format the code
+      value: |
+        ```swift
+        ```
+  - type: textarea
+    id: description
+    attributes:
+      label: Description
+      description: |
+        Any additional information you can provide for this issue, like
+         - Has this issue started occurring recently?
+         - Is the issue only happening under certain circumstances?
diff --git a/.github/ISSUE_TEMPLATE/BUG_REPORT.yml b/.github/ISSUE_TEMPLATE/BUG_REPORT.yml
index 8ed310e64fe..fc741ffe25e 100644
--- a/.github/ISSUE_TEMPLATE/BUG_REPORT.yml
+++ b/.github/ISSUE_TEMPLATE/BUG_REPORT.yml
@@ -2,17 +2,17 @@ name: Bug Report
 description: Something isn't working as expected
 labels: [bug]
 body:
- - type: textarea
-   id: description
-   attributes:
-     label: Description
-     description: |
-       A short description of the incorrect behavior.
-       If you think this issue has been recently introduced and did not occur in an
-       earlier version, please note that. If possible, include the last version that
-       the behavior was correct in addition to your current version.
- - type: textarea
-   id: steps-to-reproduce
-   attributes:
-     label: Steps to Reproduce
-     description: Replace this paragraph with an explanation of how to reproduce the incorrect behavior.
+  - type: textarea
+    id: description
+    attributes:
+      label: Description
+      description: |
+        A short description of the incorrect behavior.
+        If you think this issue has been recently introduced and did not occur in an
+        earlier version, please note that. If possible, include the last version that
+        the behavior was correct in addition to your current version.
+  - type: textarea
+    id: steps-to-reproduce
+    attributes:
+      label: Steps to Reproduce
+      description: Replace this paragraph with an explanation of how to reproduce the incorrect behavior.
diff --git a/.github/ISSUE_TEMPLATE/FEATURE_REQUEST.yml b/.github/ISSUE_TEMPLATE/FEATURE_REQUEST.yml
index 8ed16f4ea74..30f157e5593 100644
--- a/.github/ISSUE_TEMPLATE/FEATURE_REQUEST.yml
+++ b/.github/ISSUE_TEMPLATE/FEATURE_REQUEST.yml
@@ -2,12 +2,12 @@ name: Feature Request
 description: A suggestion for a new feature
 labels: [enhancement]
 body:
- - type: textarea
-   id: description
-   attributes:
-     label: Description
-     description: |
-       A description of your proposed feature.
-       Examples that show what's missing, or what new capabilities will be possible, are very helpful!
-       If this feature unlocks new use-cases please describe them.
-       Provide links to existing issues or external references/discussions, if appropriate.
+  - type: textarea
+    id: description
+    attributes:
+      label: Description
+      description: |
+        A description of your proposed feature.
+        Examples that show what's missing, or what new capabilities will be possible, are very helpful!
+        If this feature unlocks new use-cases please describe them.
+        Provide links to existing issues or external references/discussions, if appropriate.
diff --git a/.github/ISSUE_TEMPLATE/PARSER_BUG.yml b/.github/ISSUE_TEMPLATE/PARSER_BUG.yml
index 7cf33b92d27..9f66a1d9975 100644
--- a/.github/ISSUE_TEMPLATE/PARSER_BUG.yml
+++ b/.github/ISSUE_TEMPLATE/PARSER_BUG.yml
@@ -2,36 +2,36 @@ name: SwiftParser Bug
 description: A bug in the new Swift parser
 labels: [bug, SwiftParser]
 body:
- - type: markdown
-   attributes:
-     value: Thanks for taking the time to fill out this bug report! We would really appreciate if you could take the time to reduce the issue as described in [Filing Parser Bug Reports](https://swiftpackageindex.com/swiftlang/swift-syntax/main/documentation/swiftparser/filingbugreports).
- - type: dropdown
-   id: issue-type
-   attributes:
-     label: Issue Kind
-     description: What kind of issue is this? See [Filing Parser Bug Reports](https://swiftpackageindex.com/swiftlang/swift-syntax/main/documentation/swiftparser/filingbugreports) for more details.
-     options:
-       - Round-Trip Failure
-       - Parser Crash
-       - Parse of Valid Source Failed
-       - Parse of Valid Source Produced Invalid Syntax Tree
-       - Bad Diagnostic Produced
-       - Other
-       - I Don’t Know
- - type: textarea
-   id: source
-   attributes:
-     label: Source Code
-     description: The source code that, when fed into the parser, produces the bug.
-     value: |
-       ```swift
-       ```
- - type: textarea
-   id: description
-   attributes:
-     label: Description
-     description: |
-       Any additional information you can provide for this issue, like
-        - What did you expect to happen?
-        - Has this issue started occurring recently?
-        - If it’s a crash, the stack trace.
+  - type: markdown
+    attributes:
+      value: Thanks for taking the time to fill out this bug report! We would really appreciate if you could take the time to reduce the issue as described in [Filing Parser Bug Reports](https://swiftpackageindex.com/swiftlang/swift-syntax/main/documentation/swiftparser/filingbugreports).
+  - type: dropdown
+    id: issue-type
+    attributes:
+      label: Issue Kind
+      description: What kind of issue is this? See [Filing Parser Bug Reports](https://swiftpackageindex.com/swiftlang/swift-syntax/main/documentation/swiftparser/filingbugreports) for more details.
+      options:
+        - Round-Trip Failure
+        - Parser Crash
+        - Parse of Valid Source Failed
+        - Parse of Valid Source Produced Invalid Syntax Tree
+        - Bad Diagnostic Produced
+        - Other
+        - I Don’t Know
+  - type: textarea
+    id: source
+    attributes:
+      label: Source Code
+      description: The source code that, when fed into the parser, produces the bug.
+      value: |
+        ```swift
+        ```
+  - type: textarea
+    id: description
+    attributes:
+      label: Description
+      description: |
+        Any additional information you can provide for this issue, like
+         - What did you expect to happen?
+         - Has this issue started occurring recently?
+         - If it’s a crash, the stack trace.
diff --git a/.github/ISSUE_TEMPLATE/config.yml b/.github/ISSUE_TEMPLATE/config.yml
index abe51dbfea7..5bb235ac349 100644
--- a/.github/ISSUE_TEMPLATE/config.yml
+++ b/.github/ISSUE_TEMPLATE/config.yml
@@ -1,15 +1,15 @@
 # This source file is part of the Swift.org open source project
- #
- # Copyright (c) 2022 Apple Inc. and the Swift project authors
- # Licensed under Apache License v2.0 with Runtime Library Exception
- #
- # See https://swift.org/LICENSE.txt for license information
- # See https://swift.org/CONTRIBUTORS.txt for Swift project authors
+#
+# Copyright (c) 2022 Apple Inc. and the Swift project authors
+# Licensed under Apache License v2.0 with Runtime Library Exception
+#
+# See https://swift.org/LICENSE.txt for license information
+# See https://swift.org/CONTRIBUTORS.txt for Swift project authors
 
- contact_links:
-   - name: Discussion Forum
-     url: https://forums.swift.org/tags/c/development/tooling/39/swift-syntax
-     about: Ask and answer questions about SwiftSyntax
-   - name: SwiftSyntax Documentation
-     url: https://swiftpackageindex.com/swiftlang/swift-syntax/documentation/swiftsyntax
-     about: Learn about how to use the SwiftSyntax in your projects
+contact_links:
+  - name: Discussion Forum
+    url: https://forums.swift.org/tags/c/development/tooling/39/swift-syntax
+    about: Ask and answer questions about SwiftSyntax
+  - name: SwiftSyntax Documentation
+    url: https://swiftpackageindex.com/swiftlang/swift-syntax/documentation/swiftsyntax
+    about: Learn about how to use the SwiftSyntax in your projects
diff --git a/.github/workflows/pull_request.yml b/.github/workflows/pull_request.yml
index 8e482fff130..89c27f8f6a5 100644
--- a/.github/workflows/pull_request.yml
+++ b/.github/workflows/pull_request.yml
@@ -15,13 +15,8 @@ jobs:
     name: Soundness
     uses: swiftlang/github-workflows/.github/workflows/soundness.yml@main
     with:
-      # https://github.com/swiftlang/swift-syntax/issues/2986
-      api_breakage_check_enabled: false
+      api_breakage_check_allowlist_path: "Release Notes/api-breakages.txt"
       # https://github.com/swiftlang/swift-syntax/issues/2987
       docs_check_enabled: false
       # https://github.com/swiftlang/swift-syntax/issues/2988
       format_check_enabled: false
-      # https://github.com/swiftlang/swift-syntax/issues/2990
-      unacceptable_language_check_enabled: false
-      # https://github.com/swiftlang/swift-syntax/issues/2991
-      yamllint_check_enabled: false
diff --git a/.spi.yml b/.spi.yml
index 5ed74fe1c95..1118de8d5a6 100644
--- a/.spi.yml
+++ b/.spi.yml
@@ -1,4 +1,4 @@
-# This is manifest file for the Swift Package Index for it to 
+# This is manifest file for the Swift Package Index for it to
 # auto-generate and host DocC documentation.
 # For reference see https://swiftpackageindex.com/swiftpackageindex/spimanifest/documentation/spimanifest/commonusecases#Host-DocC-documentation-in-the-Swift-Package-Index.
 
@@ -6,21 +6,21 @@ version: 1
 builder:
   configs:
     - documentation_targets:
-      # First item in the list is the "landing" (default) target
-      - SwiftSyntax
-      - SwiftBasicFormat
-      - SwiftCompilerPlugin
-      - SwiftDiagnostics
-      - SwiftIDEUtils
-      - SwiftIfConfig
-      - SwiftLexicalLookup
-      - SwiftOperators
-      - SwiftParser
-      - SwiftParserDiagnostics
-      - SwiftRefactor
-      - SwiftSyntaxBuilder
-      - SwiftSyntaxMacros
-      - SwiftSyntaxMacroExpansion
-      - SwiftSyntaxMacrosGenericTestSupport
-      - SwiftSyntaxMacrosTestSupport
+        # First item in the list is the "landing" (default) target
+        - SwiftSyntax
+        - SwiftBasicFormat
+        - SwiftCompilerPlugin
+        - SwiftDiagnostics
+        - SwiftIDEUtils
+        - SwiftIfConfig
+        - SwiftLexicalLookup
+        - SwiftOperators
+        - SwiftParser
+        - SwiftParserDiagnostics
+        - SwiftRefactor
+        - SwiftSyntaxBuilder
+        - SwiftSyntaxMacros
+        - SwiftSyntaxMacroExpansion
+        - SwiftSyntaxMacrosGenericTestSupport
+        - SwiftSyntaxMacrosTestSupport
       custom_documentation_parameters: [--experimental-skip-synthesized-symbols]
diff --git a/CodeGeneration/Sources/generate-swift-syntax/templates/swiftsyntax/SyntaxBaseNodesFile.swift b/CodeGeneration/Sources/generate-swift-syntax/templates/swiftsyntax/SyntaxBaseNodesFile.swift
index e308b4364e6..b78e59e9337 100644
--- a/CodeGeneration/Sources/generate-swift-syntax/templates/swiftsyntax/SyntaxBaseNodesFile.swift
+++ b/CodeGeneration/Sources/generate-swift-syntax/templates/swiftsyntax/SyntaxBaseNodesFile.swift
@@ -42,7 +42,7 @@ let syntaxBaseNodesFile = SourceFileSyntax(leadingTrivia: copyrightHeader) {
       /// These methods enable casting between syntax node types within the same
       /// base node protocol hierarchy (e.g., ``DeclSyntaxProtocol``).
       ///
-      /// While ``SyntaxProtocol`` offers general casting methods (``SyntaxProtocol.as(_:)``, 
+      /// While ``SyntaxProtocol`` offers general casting methods (``SyntaxProtocol.as(_:)``,
       /// ``SyntaxProtocol.is(_:)``, and ``SyntaxProtocol.cast(_:)``), these often aren't
       /// appropriate for use on types conforming to a specific base node protocol
       /// like ``\#(node.kind.protocolType)``. That's because at this level,
@@ -51,7 +51,7 @@ let syntaxBaseNodesFile = SourceFileSyntax(leadingTrivia: copyrightHeader) {
       ///
       /// To guide developers toward correct usage, this extension provides overloads
       /// of these casting methods that are restricted to the same base node type.
-      /// Furthermore, it marks the inherited casting methods from ``SyntaxProtocol`` as 
+      /// Furthermore, it marks the inherited casting methods from ``SyntaxProtocol`` as
       /// deprecated, indicating that they will always fail when used in this context.
       extension \#(node.kind.protocolType) {
         /// Checks if the current syntax node can be cast to a given specialized syntax type.
@@ -184,9 +184,8 @@ let syntaxBaseNodesFile = SourceFileSyntax(leadingTrivia: copyrightHeader) {
         """
         /// Create a \(raw: node.kind.doccLink) node from a specialized syntax node.
         public init(_ syntax: __shared some \(node.kind.protocolType)) {
-          // We know this cast is going to succeed. Go through init(_: SyntaxData)
-          // to do a sanity check and verify the kind matches in debug builds and get
-          // maximum performance in release builds.
+          // We know this cast is going to succeed. Go through `init(_: SyntaxData)` just to double-check and
+          // verify the kind matches in debug builds and get maximum performance in release builds.
           self = Syntax(syntax).cast(Self.self)
         }
         """
@@ -205,9 +204,8 @@ let syntaxBaseNodesFile = SourceFileSyntax(leadingTrivia: copyrightHeader) {
       DeclSyntax(
         """
         public init(fromProtocol syntax: __shared \(node.kind.protocolType)) {
-          // We know this cast is going to succeed. Go through init(_: SyntaxData)
-          // to do a sanity check and verify the kind matches in debug builds and get
-          // maximum performance in release builds.
+          // We know this cast is going to succeed. Go through `init(_: SyntaxData)` just to double-check and
+          // verify the kind matches in debug builds and get maximum performance in release builds.
           self = Syntax(syntax).cast(Self.self)
         }
         """
diff --git a/Contributor Documentation/API Breakage Checks.md b/Contributor Documentation/API Breakage Checks.md
new file mode 100644
index 00000000000..968b9353ad3
--- /dev/null
+++ b/Contributor Documentation/API Breakage Checks.md	
@@ -0,0 +1,5 @@
+# API Breakage Checks
+
+We have a CI jobs that checks for API breakages. Since swift-syntax releases increase the major version number, it is possible to make API-breaking changes – but we should avoid them whenever possible to avoid churn on clients when they update to a new swift-syntax version.
+
+If your change contains an API breaking change, add the change to `api-breakages.txt`. All API breaking changes should be accompanied by an [RFC](RFC%20Process.md).
diff --git a/Contributor Documentation/README.md b/Contributor Documentation/README.md
index 37c106886ee..72cff47f7e8 100644
--- a/Contributor Documentation/README.md	
+++ b/Contributor Documentation/README.md	
@@ -2,6 +2,7 @@
 
 The following documentation documents are primarily intended for developers of swift-syntax.
 
+- [API Breakage Checks](API%20Breakage%20Checks.md)
 - [Changing Swift Syntax](Changing%20Swift%20Syntax.md)
 - [Filing Parser Bug Reports](Filing%20Parser%20Bug%20Reports.md)
 - [Fixing Bugs](Fixing%20Bugs.md)
diff --git a/Sources/SwiftParser/Expressions.swift b/Sources/SwiftParser/Expressions.swift
index 43ffba08257..c7cd30757b8 100644
--- a/Sources/SwiftParser/Expressions.swift
+++ b/Sources/SwiftParser/Expressions.swift
@@ -583,7 +583,7 @@ extension Parser {
   ) -> RawExprSyntax {
     // Try parse a single value statement as an expression (e.g do/if/switch).
     // Note we do this here in parseUnaryExpression as we don't allow postfix
-    // syntax to hang off such expressions to avoid ambiguities such as postfix
+    // syntax to be attached to such expressions to avoid ambiguities such as postfix
     // '.member', which can currently be parsed as a static dot member for a
     // result builder.
     switch self.at(anyIn: SingleValueStatementExpression.self) {
diff --git a/Sources/SwiftSyntax/generated/SyntaxBaseNodes.swift b/Sources/SwiftSyntax/generated/SyntaxBaseNodes.swift
index c48884aa317..255f7fc5214 100644
--- a/Sources/SwiftSyntax/generated/SyntaxBaseNodes.swift
+++ b/Sources/SwiftSyntax/generated/SyntaxBaseNodes.swift
@@ -26,7 +26,7 @@ public protocol DeclSyntaxProtocol: SyntaxProtocol {}
 /// These methods enable casting between syntax node types within the same
 /// base node protocol hierarchy (e.g., ``DeclSyntaxProtocol``).
 ///
-/// While ``SyntaxProtocol`` offers general casting methods (``SyntaxProtocol.as(_:)``, 
+/// While ``SyntaxProtocol`` offers general casting methods (``SyntaxProtocol.as(_:)``,
 /// ``SyntaxProtocol.is(_:)``, and ``SyntaxProtocol.cast(_:)``), these often aren't
 /// appropriate for use on types conforming to a specific base node protocol
 /// like ``DeclSyntaxProtocol``. That's because at this level,
@@ -35,7 +35,7 @@ public protocol DeclSyntaxProtocol: SyntaxProtocol {}
 ///
 /// To guide developers toward correct usage, this extension provides overloads
 /// of these casting methods that are restricted to the same base node type.
-/// Furthermore, it marks the inherited casting methods from ``SyntaxProtocol`` as 
+/// Furthermore, it marks the inherited casting methods from ``SyntaxProtocol`` as
 /// deprecated, indicating that they will always fail when used in this context.
 extension DeclSyntaxProtocol {
   /// Checks if the current syntax node can be cast to a given specialized syntax type.
@@ -184,9 +184,8 @@ public struct DeclSyntax: DeclSyntaxProtocol, SyntaxHashable {
 
   /// Create a ``DeclSyntax`` node from a specialized syntax node.
   public init(_ syntax: __shared some DeclSyntaxProtocol) {
-    // We know this cast is going to succeed. Go through init(_: SyntaxData)
-    // to do a sanity check and verify the kind matches in debug builds and get
-    // maximum performance in release builds.
+    // We know this cast is going to succeed. Go through `init(_: SyntaxData)` just to double-check and
+    // verify the kind matches in debug builds and get maximum performance in release builds.
     self = Syntax(syntax).cast(Self.self)
   }
 
@@ -199,9 +198,8 @@ public struct DeclSyntax: DeclSyntaxProtocol, SyntaxHashable {
   }
 
   public init(fromProtocol syntax: __shared DeclSyntaxProtocol) {
-    // We know this cast is going to succeed. Go through init(_: SyntaxData)
-    // to do a sanity check and verify the kind matches in debug builds and get
-    // maximum performance in release builds.
+    // We know this cast is going to succeed. Go through `init(_: SyntaxData)` just to double-check and
+    // verify the kind matches in debug builds and get maximum performance in release builds.
     self = Syntax(syntax).cast(Self.self)
   }
 
@@ -327,7 +325,7 @@ public protocol ExprSyntaxProtocol: SyntaxProtocol {}
 /// These methods enable casting between syntax node types within the same
 /// base node protocol hierarchy (e.g., ``DeclSyntaxProtocol``).
 ///
-/// While ``SyntaxProtocol`` offers general casting methods (``SyntaxProtocol.as(_:)``, 
+/// While ``SyntaxProtocol`` offers general casting methods (``SyntaxProtocol.as(_:)``,
 /// ``SyntaxProtocol.is(_:)``, and ``SyntaxProtocol.cast(_:)``), these often aren't
 /// appropriate for use on types conforming to a specific base node protocol
 /// like ``ExprSyntaxProtocol``. That's because at this level,
@@ -336,7 +334,7 @@ public protocol ExprSyntaxProtocol: SyntaxProtocol {}
 ///
 /// To guide developers toward correct usage, this extension provides overloads
 /// of these casting methods that are restricted to the same base node type.
-/// Furthermore, it marks the inherited casting methods from ``SyntaxProtocol`` as 
+/// Furthermore, it marks the inherited casting methods from ``SyntaxProtocol`` as
 /// deprecated, indicating that they will always fail when used in this context.
 extension ExprSyntaxProtocol {
   /// Checks if the current syntax node can be cast to a given specialized syntax type.
@@ -512,9 +510,8 @@ public struct ExprSyntax: ExprSyntaxProtocol, SyntaxHashable {
 
   /// Create a ``ExprSyntax`` node from a specialized syntax node.
   public init(_ syntax: __shared some ExprSyntaxProtocol) {
-    // We know this cast is going to succeed. Go through init(_: SyntaxData)
-    // to do a sanity check and verify the kind matches in debug builds and get
-    // maximum performance in release builds.
+    // We know this cast is going to succeed. Go through `init(_: SyntaxData)` just to double-check and
+    // verify the kind matches in debug builds and get maximum performance in release builds.
     self = Syntax(syntax).cast(Self.self)
   }
 
@@ -527,9 +524,8 @@ public struct ExprSyntax: ExprSyntaxProtocol, SyntaxHashable {
   }
 
   public init(fromProtocol syntax: __shared ExprSyntaxProtocol) {
-    // We know this cast is going to succeed. Go through init(_: SyntaxData)
-    // to do a sanity check and verify the kind matches in debug builds and get
-    // maximum performance in release builds.
+    // We know this cast is going to succeed. Go through `init(_: SyntaxData)` just to double-check and
+    // verify the kind matches in debug builds and get maximum performance in release builds.
     self = Syntax(syntax).cast(Self.self)
   }
 
@@ -685,7 +681,7 @@ public protocol PatternSyntaxProtocol: SyntaxProtocol {}
 /// These methods enable casting between syntax node types within the same
 /// base node protocol hierarchy (e.g., ``DeclSyntaxProtocol``).
 ///
-/// While ``SyntaxProtocol`` offers general casting methods (``SyntaxProtocol.as(_:)``, 
+/// While ``SyntaxProtocol`` offers general casting methods (``SyntaxProtocol.as(_:)``,
 /// ``SyntaxProtocol.is(_:)``, and ``SyntaxProtocol.cast(_:)``), these often aren't
 /// appropriate for use on types conforming to a specific base node protocol
 /// like ``PatternSyntaxProtocol``. That's because at this level,
@@ -694,7 +690,7 @@ public protocol PatternSyntaxProtocol: SyntaxProtocol {}
 ///
 /// To guide developers toward correct usage, this extension provides overloads
 /// of these casting methods that are restricted to the same base node type.
-/// Furthermore, it marks the inherited casting methods from ``SyntaxProtocol`` as 
+/// Furthermore, it marks the inherited casting methods from ``SyntaxProtocol`` as
 /// deprecated, indicating that they will always fail when used in this context.
 extension PatternSyntaxProtocol {
   /// Checks if the current syntax node can be cast to a given specialized syntax type.
@@ -826,9 +822,8 @@ public struct PatternSyntax: PatternSyntaxProtocol, SyntaxHashable {
 
   /// Create a ``PatternSyntax`` node from a specialized syntax node.
   public init(_ syntax: __shared some PatternSyntaxProtocol) {
-    // We know this cast is going to succeed. Go through init(_: SyntaxData)
-    // to do a sanity check and verify the kind matches in debug builds and get
-    // maximum performance in release builds.
+    // We know this cast is going to succeed. Go through `init(_: SyntaxData)` just to double-check and
+    // verify the kind matches in debug builds and get maximum performance in release builds.
     self = Syntax(syntax).cast(Self.self)
   }
 
@@ -841,9 +836,8 @@ public struct PatternSyntax: PatternSyntaxProtocol, SyntaxHashable {
   }
 
   public init(fromProtocol syntax: __shared PatternSyntaxProtocol) {
-    // We know this cast is going to succeed. Go through init(_: SyntaxData)
-    // to do a sanity check and verify the kind matches in debug builds and get
-    // maximum performance in release builds.
+    // We know this cast is going to succeed. Go through `init(_: SyntaxData)` just to double-check and
+    // verify the kind matches in debug builds and get maximum performance in release builds.
     self = Syntax(syntax).cast(Self.self)
   }
 
@@ -952,7 +946,7 @@ public protocol StmtSyntaxProtocol: SyntaxProtocol {}
 /// These methods enable casting between syntax node types within the same
 /// base node protocol hierarchy (e.g., ``DeclSyntaxProtocol``).
 ///
-/// While ``SyntaxProtocol`` offers general casting methods (``SyntaxProtocol.as(_:)``, 
+/// While ``SyntaxProtocol`` offers general casting methods (``SyntaxProtocol.as(_:)``,
 /// ``SyntaxProtocol.is(_:)``, and ``SyntaxProtocol.cast(_:)``), these often aren't
 /// appropriate for use on types conforming to a specific base node protocol
 /// like ``StmtSyntaxProtocol``. That's because at this level,
@@ -961,7 +955,7 @@ public protocol StmtSyntaxProtocol: SyntaxProtocol {}
 ///
 /// To guide developers toward correct usage, this extension provides overloads
 /// of these casting methods that are restricted to the same base node type.
-/// Furthermore, it marks the inherited casting methods from ``SyntaxProtocol`` as 
+/// Furthermore, it marks the inherited casting methods from ``SyntaxProtocol`` as
 /// deprecated, indicating that they will always fail when used in this context.
 extension StmtSyntaxProtocol {
   /// Checks if the current syntax node can be cast to a given specialized syntax type.
@@ -1102,9 +1096,8 @@ public struct StmtSyntax: StmtSyntaxProtocol, SyntaxHashable {
 
   /// Create a ``StmtSyntax`` node from a specialized syntax node.
   public init(_ syntax: __shared some StmtSyntaxProtocol) {
-    // We know this cast is going to succeed. Go through init(_: SyntaxData)
-    // to do a sanity check and verify the kind matches in debug builds and get
-    // maximum performance in release builds.
+    // We know this cast is going to succeed. Go through `init(_: SyntaxData)` just to double-check and
+    // verify the kind matches in debug builds and get maximum performance in release builds.
     self = Syntax(syntax).cast(Self.self)
   }
 
@@ -1117,9 +1110,8 @@ public struct StmtSyntax: StmtSyntaxProtocol, SyntaxHashable {
   }
 
   public init(fromProtocol syntax: __shared StmtSyntaxProtocol) {
-    // We know this cast is going to succeed. Go through init(_: SyntaxData)
-    // to do a sanity check and verify the kind matches in debug builds and get
-    // maximum performance in release builds.
+    // We know this cast is going to succeed. Go through `init(_: SyntaxData)` just to double-check and
+    // verify the kind matches in debug builds and get maximum performance in release builds.
     self = Syntax(syntax).cast(Self.self)
   }
 
@@ -1238,7 +1230,7 @@ public protocol TypeSyntaxProtocol: SyntaxProtocol {}
 /// These methods enable casting between syntax node types within the same
 /// base node protocol hierarchy (e.g., ``DeclSyntaxProtocol``).
 ///
-/// While ``SyntaxProtocol`` offers general casting methods (``SyntaxProtocol.as(_:)``, 
+/// While ``SyntaxProtocol`` offers general casting methods (``SyntaxProtocol.as(_:)``,
 /// ``SyntaxProtocol.is(_:)``, and ``SyntaxProtocol.cast(_:)``), these often aren't
 /// appropriate for use on types conforming to a specific base node protocol
 /// like ``TypeSyntaxProtocol``. That's because at this level,
@@ -1247,7 +1239,7 @@ public protocol TypeSyntaxProtocol: SyntaxProtocol {}
 ///
 /// To guide developers toward correct usage, this extension provides overloads
 /// of these casting methods that are restricted to the same base node type.
-/// Furthermore, it marks the inherited casting methods from ``SyntaxProtocol`` as 
+/// Furthermore, it marks the inherited casting methods from ``SyntaxProtocol`` as
 /// deprecated, indicating that they will always fail when used in this context.
 extension TypeSyntaxProtocol {
   /// Checks if the current syntax node can be cast to a given specialized syntax type.
@@ -1390,9 +1382,8 @@ public struct TypeSyntax: TypeSyntaxProtocol, SyntaxHashable {
 
   /// Create a ``TypeSyntax`` node from a specialized syntax node.
   public init(_ syntax: __shared some TypeSyntaxProtocol) {
-    // We know this cast is going to succeed. Go through init(_: SyntaxData)
-    // to do a sanity check and verify the kind matches in debug builds and get
-    // maximum performance in release builds.
+    // We know this cast is going to succeed. Go through `init(_: SyntaxData)` just to double-check and
+    // verify the kind matches in debug builds and get maximum performance in release builds.
     self = Syntax(syntax).cast(Self.self)
   }
 
@@ -1405,9 +1396,8 @@ public struct TypeSyntax: TypeSyntaxProtocol, SyntaxHashable {
   }
 
   public init(fromProtocol syntax: __shared TypeSyntaxProtocol) {
-    // We know this cast is going to succeed. Go through init(_: SyntaxData)
-    // to do a sanity check and verify the kind matches in debug builds and get
-    // maximum performance in release builds.
+    // We know this cast is going to succeed. Go through `init(_: SyntaxData)` just to double-check and
+    // verify the kind matches in debug builds and get maximum performance in release builds.
     self = Syntax(syntax).cast(Self.self)
   }
 
diff --git a/SwiftParserCLI/Sources/swift-parser-cli/Commands/Reduce.swift b/SwiftParserCLI/Sources/swift-parser-cli/Commands/Reduce.swift
index 393df87845d..aeb7301a546 100644
--- a/SwiftParserCLI/Sources/swift-parser-cli/Commands/Reduce.swift
+++ b/SwiftParserCLI/Sources/swift-parser-cli/Commands/Reduce.swift
@@ -97,7 +97,7 @@ struct Reduce: ParsableCommand {
         #if os(Windows)
         _ = TerminateProcess(process.processHandle, 0)
         #else
-        kill(pid_t(process.processIdentifier), SIGKILL)
+        kill(pid_t(process.processIdentifier), SIGKILL)  // ignore-unacceptable-language
         #endif
         return .timeout
       }
diff --git a/SwiftSyntaxDevUtils/Sources/swift-syntax-dev-utils/commands/VerifySourceCode.swift b/SwiftSyntaxDevUtils/Sources/swift-syntax-dev-utils/commands/VerifySourceCode.swift
index 5f339341ae0..02c66d15e2f 100644
--- a/SwiftSyntaxDevUtils/Sources/swift-syntax-dev-utils/commands/VerifySourceCode.swift
+++ b/SwiftSyntaxDevUtils/Sources/swift-syntax-dev-utils/commands/VerifySourceCode.swift
@@ -138,7 +138,7 @@ struct VerifySpiYmlExecutor {
   /// a dependency from this script on a YAML parser and that just doesn’t seem worth it.
   private func targetsInSwiftPackageIndexManifest() throws -> [String] {
     let extractTargetRegex = Regex {
-      #/^      - /#
+      #/^        - /#
       Capture(ZeroOrMore(.word))
       #/$/#
     }
diff --git a/api-breakages.txt b/api-breakages.txt
new file mode 100644
index 00000000000..4f5611e7187
--- /dev/null
+++ b/api-breakages.txt
@@ -0,0 +1,2 @@
+6.2
+---