diff --git a/.claude/settings.json b/.claude/settings.json
new file mode 100644
index 00000000000..1ca8b047bc6
--- /dev/null
+++ b/.claude/settings.json
@@ -0,0 +1,22 @@
+{
+  "enabledPlugins": {
+    "rust-analyzer-lsp@claude-plugins-official": true
+  }
+  "permissions": {
+    "allow": [
+      "WebFetch(domain:checkerframework.org)",
+      "Bash(mkdir:*)",
+      "Bash(./gradlew:*)",
+      "Bash(git -C /home/mernst/research/types/checker-framework-fork-mernst-branch-override-order diff master..override-order --stat)"
+      "Bash(git -C /home/mernst/research/types/checker-framework-fork-mernst-branch-override-order log master..override-order --oneline)",
+      "Bash(java:*)",
+      "Bash(javac:*)",
+      "Bash(ls)",
+      "Bash(timeout 300 ./gradlew:*)",
+      "Bash(./x.py check:*)",
+      "Read(//scratch/mernst/**)"
+    ],
+    "deny": [],
+    "ask": []
+  }
+}
diff --git a/.coderabbit.yaml b/.coderabbit.yaml
new file mode 100644
index 00000000000..bcd9365ae43
--- /dev/null
+++ b/.coderabbit.yaml
@@ -0,0 +1,46 @@
+# yaml-language-server: $schema=https://coderabbit.ai/integrations/schema.v2.json
+
+language: "en-US"
+
+reviews:
+  profile: "assertive"
+  high_level_summary: false
+  review_status: false
+  collapse_walkthrough: true
+  changed_files_summary: false
+  sequence_diagrams: false
+  estimate_code_review_effort: false
+  in_progress_fortune: false
+  poem: false
+  path_filters:
+    - "!**/build/**"
+    - "!**/out/**"
+    - "!**/.gradle/**"
+    - "!**/.idea/**"
+    - "!**/node_modules/**"
+  auto_review:
+    auto_pause_after_reviewed_commits: 0
+    ignore_title_keywords:
+      - "wip"
+      - "draft"
+    ignore_usernames:
+      - "dependabot"
+      - "dependabot[bot]"
+      - "mend"
+      - "renovate"
+      - "renovate[bot]"
+  pre_merge_checks:
+    title:
+      mode: "off"
+    description:
+      mode: "off"
+
+chat:
+  art: false
+
+knowledge_base:
+  code_guidelines:
+    enabled: true
+    filePatterns:
+      - "**/.cursorrules"
+      - "**/CODING_STANDARDS.md"
diff --git a/src/java.base/share/classes/java/lang/System.java b/src/java.base/share/classes/java/lang/System.java
index fd8cf225401..9a6a386a39b 100644
--- a/src/java.base/share/classes/java/lang/System.java
+++ b/src/java.base/share/classes/java/lang/System.java
@@ -31,6 +31,7 @@
 import org.checkerframework.checker.mustcall.qual.MustCall;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.regex.qual.Regex;
 import org.checkerframework.checker.signedness.qual.PolySigned;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -122,7 +123,7 @@
  *
  * @since   1.0
  */
-@AnnotatedFor({"index", "interning", "lock", "mustcall", "nullness", "signedness"})
+@AnnotatedFor({"index", "interning", "lock", "mustcall", "nullness", "regex", "signedness"})
 public final @UsesObjectEquals class System {
     /* Register the natives via the static initializer.
      *
@@ -905,7 +906,7 @@ public static Properties getProperties() {
      * @since 1.7
      */
     @Pure
-    public static String lineSeparator() {
+    public static @Regex String lineSeparator() {
         return lineSeparator;
     }
 
diff --git a/src/java.base/share/classes/java/lang/ThreadGroup.java b/src/java.base/share/classes/java/lang/ThreadGroup.java
index f994598eee3..8ec6a4fb649 100644
--- a/src/java.base/share/classes/java/lang/ThreadGroup.java
+++ b/src/java.base/share/classes/java/lang/ThreadGroup.java
@@ -550,7 +550,8 @@ public int activeGroupCount() {
      *          the current thread cannot access this thread group
      */
     public @NonNegative int enumerate(ThreadGroup[] list, boolean recurse) {
-        Objects.requireNonNull(list);        checkAccess();
+        Objects.requireNonNull(list);
+        checkAccess();
         return enumerate(list, 0, recurse);
     }
 
diff --git a/src/java.base/share/classes/java/net/HttpURLConnection.java b/src/java.base/share/classes/java/net/HttpURLConnection.java
index b501fa25e45..8fc5fcc8284 100644
--- a/src/java.base/share/classes/java/net/HttpURLConnection.java
+++ b/src/java.base/share/classes/java/net/HttpURLConnection.java
@@ -25,6 +25,9 @@
 
 package java.net;
 
+import org.checkerframework.checker.mustcall.qual.InheritableMustCall;
+import org.checkerframework.framework.qual.AnnotatedFor;
+
 import java.io.InputStream;
 import java.io.IOException;
 import java.security.Permission;
@@ -66,6 +69,8 @@
  * @see     java.net.HttpURLConnection#disconnect()
  * @since 1.1
  */
+@AnnotatedFor("mustcall")
+@InheritableMustCall("disconnect")
 public abstract class HttpURLConnection extends URLConnection {
     /* instance variables */
 
diff --git a/src/java.base/share/classes/sun/net/www/protocol/http/HttpURLConnection.java b/src/java.base/share/classes/sun/net/www/protocol/http/HttpURLConnection.java
index cbd24ee2f0b..da3ab40ec6a 100644
--- a/src/java.base/share/classes/sun/net/www/protocol/http/HttpURLConnection.java
+++ b/src/java.base/share/classes/sun/net/www/protocol/http/HttpURLConnection.java
@@ -25,6 +25,9 @@
 
 package sun.net.www.protocol.http;
 
+import org.checkerframework.checker.mustcall.qual.InheritableMustCall;
+import org.checkerframework.framework.qual.AnnotatedFor;
+
 import java.security.PrivilegedAction;
 import java.util.Arrays;
 import java.net.URL;
@@ -98,6 +101,8 @@
  */
 
 
+@AnnotatedFor("mustcall")
+@InheritableMustCall("disconnect")
 public class HttpURLConnection extends java.net.HttpURLConnection {
 
     static final String HTTP_CONNECT = "CONNECT";
diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/api/ClientCodeWrapper.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/api/ClientCodeWrapper.java
index e737f56b362..89b78a63d5b 100644
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/api/ClientCodeWrapper.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/api/ClientCodeWrapper.java
@@ -340,7 +340,8 @@ public FileObject getFileForOutputForOriginatingFiles(Location location, String
             }
         }
 
-        @Override @DefinedBy(Api.COMPILER)        public boolean contains(Location location, FileObject file) throws IOException {
+        @Override @DefinedBy(Api.COMPILER)
+        public boolean contains(Location location, FileObject file) throws IOException {
             try {
                 return clientJavaFileManager.contains(location, unwrap(file));
             } catch (ClientCodeException e) {