# Improvements to Pipelines Change Detection

We're excited to introduce significant improvements to how Gruntwork Pipelines detects and processes changes in your infrastructure code. These enhancements make Pipelines more predictable and responsive to the full range of modifications in your codebase.

We've added several opt-in feature flags that you can enable by setting environment variables in your Pipelines configuration. You can enable these independently, or set `PIPELINES_FEATURE_EXPERIMENT_ALL` to `true` to enable the full set of functionality described below.

_We expect to enable these behaviors by default in a future major version of Pipelines._ Check out our [**feature flags documentation**](https://docs.gruntwork.io/2.0/reference/pipelines/feature-flags) for more details on how to implement these improvements in your workflow in the meantime.

## Improved Unit File Change Detection

**Feature Flag:**`PIPELINES_FEATURE_EXPERIMENT_COLOCATED_FILE_UNIT_CHANGE_DETECTION`

This flag enhances how Pipelines detects changes within Terragrunt Units (any non-root directory of the repo that contains a `terragrunt.hcl` file) to better align with our semantic notion of a unit.

When enabled, any file modified within a Terragrunt Unit will trigger a **ModuleChanged** event for that unit, causing Pipelines to run a Terragrunt Plan/Apply operation for the affected directory. This includes files like `terragrunt.lock.hcl` and other support files within the unit. Previously, these would trigger a **FileChanged** event, which disregarded the semantic connection to the unit being affected.

For example, consider a unit containing these files:

- tags.yml
- dir1/terragrunt.hcl
- dir1/myvars.json

With this new flag enabled:

- A change to `dir1/myvars.json` is detected as a **ModuleChanged** event for `dir1`, triggering a Terragrunt Plan/Apply for this directory.
- A change to `tags.yml` is still detected as a **FileChanged** event, causing Pipelines to run Terragrunt with `queue-include-units-reading` for this file.

## Smarter Change Consolidation

**Feature Flag:** **`PIPELINES_FEATURE_EXPERIMENT_AGGRESSIVE_CONSOLIDATION`**

This flag improves how Pipelines consolidates and executes Terragrunt operations to improve dependency handling and minimize redundant change execution. When enabled, Pipelines will consolidate as many Terragrunt plan/apply changes as possible into a single `run --all` job. This reduces duplicated work when, for example, both FileChanged and EnvCommon events would trigger plans for the same unit.

## Minimizing Blast Radius

**Feature Flag:**`PIPELINES_FEATURE_EXPERIMENT_MINIMIZE_BLAST_RADIUS`

Safety is a core principle of Gruntwork Pipelines. In that spirit, we’re making improvements to ensure that the blast radius of your changes remains as localized as possible by default. With this flag enabled, Pipelines will execute Terragrunt `run --all` with the `--queue-strict-include` option, which helps reduce the blast radius of per-unit changes as dependencies will no longer run automatically when dependents are modified. This ensures that `run --all` behaviors are consistent with runs for individual units.