diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index b67f6f2..43f7c10 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -25,10 +25,10 @@ jobs:
         run: make docs-site
 
   build:
-    runs-on: macos-15
+    runs-on: macos-26
     timeout-minutes: 20
     env:
-      DEVELOPER_DIR: /Applications/Xcode_26.0.1.app/Contents/Developer
+      DEVELOPER_DIR: /Applications/Xcode_26.6.app/Contents/Developer
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       - name: Swift version
diff --git a/.github/workflows/codeql.yml b/.github/workflows/codeql.yml
index 6081a2d..0aea8c8 100644
--- a/.github/workflows/codeql.yml
+++ b/.github/workflows/codeql.yml
@@ -33,14 +33,14 @@ jobs:
             runner: ubuntu-latest
             build-mode: none
           - language: swift
-            runner: macos-15
+            runner: macos-26
             build-mode: manual
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       - name: Prepare Swift dependencies
         if: matrix.language == 'swift'
         env:
-          DEVELOPER_DIR: /Applications/Xcode_26.0.1.app/Contents/Developer
+          DEVELOPER_DIR: /Applications/Xcode_26.6.app/Contents/Developer
         run: |
           echo "DEVELOPER_DIR=$DEVELOPER_DIR" >> "$GITHUB_ENV"
           swift --version
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1cd69fb..947ca27 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## Unreleased
 
+- Update CI and Swift CodeQL builds to Xcode 26.6 on macOS 26 while retaining the macOS 14 deployment target.
 - Reject conflicting list mutations and missing targets before accessing Reminders, preventing combinations such as `--delete --rename` from silently deleting a list.
 - Respect `--` when interpreting help/version flags and allow the CLI executable to be renamed without breaking command resolution.
 - Reject infinite geofence radii before geocoding or saving a reminder.
diff --git a/README.md b/README.md
index 91f4da2..48c321f 100644
--- a/README.md
+++ b/README.md
@@ -303,7 +303,7 @@ Supporting those would require Apple to expose new public APIs or a separate non
 ## Development
 
 The package manager is pinned in `package.json`, and `.node-version` selects the docs runtime.
-CI uses Xcode 26.0.1 (Swift 6.2), builds both release architectures, and runs the universal CLI natively.
+CI uses Xcode 26.6 on macOS 26, builds both release architectures, and runs the universal CLI natively.
 `make check` runs the Swift tests once with coverage and retains the 90% RemindCore gate.
 CodeQL scans Swift with an explicit package build after dependency resolution, plus JavaScript/TypeScript and Actions.