anchor.diff:  
   <h3 class="h3-caps">BUILDKITE_CLEAN_CHECKOUT</h3>
   
  -Whether the build should perform a clean checkout. This variable is read by ??? during ???. It can only be set by exporting the environment variable in the `environment` or `pre-checkout` hooks.
  +Whether the build should perform a clean checkout. The variable is read during the default checkout phase of the bootstrap and can be overridden in `environment` or `pre-checkout` hooks.
   
   Values: `"true"` or `"false"`
   
  
positive.code: 
  <h3 class="h3-caps">BUILDKITE_AGENT_ENDPOINT</h3>
  
  The value of the `endpoint` [agent configuration option](/docs/agent/v3/configuration). The value cannot be modified as an environment variable. This variable is read by the `buildkite-agent artifact ???` commands.
  
  Example: `"https://agent.buildkite.com/v3"`
  
  <h3 class="h3-caps">BUILDKITE_AGENT_EXPERIMENT</h3>
  
  
negative.code: 
  <h3 class="h3-caps">BUILDKITE_PLUGIN_VALIDATION</h3>
  
  Whether to enable plugin validation (currently experimental). This variable is read by the bootstrap during the `checkout` phase. The value can be set as an environment variable in a `pipeline.yml` file, or in `environment` and `pre-checkout` hooks. It can also be enabled using the `plugin-validation` [agent configuration option](/docs/agent/v3/configuration). 
  
  Values: `"true"` and `"false"`
  
  