Use yarn 4

.gitignore

@@ -94,3 +94,13 @@ db/data/nhs-gp-practices.csv
 # Python
 __pycache__/
 *.pyc
+
+# Yarn without zero-installs
+# See https://yarnpkg.com/getting-started/qa#which-files-should-be-gitignored
+.pnp.*
+.yarn/*
+!.yarn/patches
+!.yarn/plugins
+!.yarn/releases
+!.yarn/sdks
+!.yarn/versions

.tool-versions

@@ -7,5 +7,5 @@ python     3.14.4
 ruby       4.0.3
 shellcheck 0.11.0
 yamllint   1.38.0
-yarn       4.9.4
+yarn       4.14.1
 uv         0.11.7

.yarnrc.yml

@@ -0,0 +1,6 @@
+approvedGitRepositories:
+  - "**"
+
+enableScripts: true
+
+nodeLinker: node-modules

Dockerfile

@@ -37,7 +37,7 @@ RUN apt-get update -qq && \
 
 # Install JavaScript dependencies
 ARG NODE_VERSION=22.15.0
-ARG YARN_VERSION=1.22.19
+ARG YARN_VERSION=4.14.1
 ENV PATH=/usr/local/node/bin:$PATH
 RUN curl -sL --ssl https://github.com/nodenv/node-build/archive/master.tar.gz | tar xz -C /tmp/ && \
     /tmp/node-build-master/bin/node-build "${NODE_VERSION}" /usr/local/node && \

package.json

@@ -1,6 +1,5 @@
 {
   "name": "app",
-  "private": "true",
   "dependencies": {
     "@hotwired/turbo-rails": "^8.0.23",
     "accessible-autocomplete": "^3.0.1",
@@ -44,5 +43,6 @@
         }
       ]
     }
-  }
+  },
+  "packageManager": "yarn@4.14.1"
 }