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+<!--
+  Licensed to the Apache Software Foundation (ASF) under one
+  or more contributor license agreements.  See the NOTICE file
+  distributed with this work for additional information
+  regarding copyright ownership.  The ASF licenses this file
+  to you under the Apache License, Version 2.0 (the
+  "License"); you may not use this file except in compliance
+  with the License.  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing,
+  software distributed under the License is distributed on an
+  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+  KIND, either express or implied.  See the License for the
+  specific language governing permissions and limitations
+  under the License.
+-->
+
+# AGENTS.md
+
+This file provides guidance for AI coding agents that work in this repository.
+
+## Build and verification
+
+- Format the code before you commit:
+  - `mvn spotless:apply`
+- Verify that the pull request is ready:
+  - `mvn spotless:check`
+  - `mvn checkstyle:check`
+  - `mvn apache-rat:check`
+  - `mvn verify` (runs the unit tests and the RAT license check)
+- Make sure all of the commands above pass before you open or update a pull
+  request.
+
+## Test-first programming
+
+Write a failing test before you implement a fix or a feature:
+
+1. Write a test that reproduces the bug, or that specifies the new behavior.
+2. Run the test and confirm that it fails. The failure must match the bug that
+   you are fixing.
+3. Implement the change.
+4. Run the test again and confirm that it passes.
+5. Run `mvn verify` to confirm that nothing else is broken.
+
+## Documentation style
+
+Use ASD-STE100 Simplified Technical English for documentation. This includes
+the README, the site documentation, javadoc, and code comments:
+
+- Write short sentences.
+- Write one idea per sentence.
+- Use only the approved vocabulary and the approved meanings for words.
+- Use the active voice.
+- Write precisely and without ambiguity.