# Component Config Files in modifications/base/ Get Overwritten during Seed Project build

**URL:** <https://community.interop.io/t/component-config-files-in-modifications-base-get-overwritten-during-seed-project-build/578>\
**Category:** io.Connect Desktop\
**Tags:** FAQs\
**Created:** [May 13, 2026, 6:59am UTC](https://community.interop.io/t/component-config-files-in-modifications-base-get-overwritten-during-seed-project-build/578 "2026-05-13T06:59:19Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![toni.petrov](https://yyz2.discourse-cdn.com/flex028/user_avatar/community.interop.io/toni.petrov/32/17_2.png) [@toni.petrov](https://community.interop.io/u/toni.petrov)\
**Post date:** [May 13, 2026, 6:59am UTC](https://community.interop.io/t/component-config-files-in-modifications-base-get-overwritten-during-seed-project-build/578/1 "2026-05-13T06:59:19Z")

</div>

## Problem

When you place a custom app definition for some components in `modifications/base/iocd/config/apps/`, for example:

```auto
modifications/base/iocd/config/apps/bbg-mdf.json

```

Every time you run `iocd build` (or `npm run build`), the file is replaced with the default one shipped, and your customizations are lost.

This only happens for **some** files in `modifications/base/iocd/config/apps/`. Other files placed in the same folder (e.g. `bbg.json` placed alongside `bbg-mdf.json`) are untouched by the build.

* * *

## Why This Happens

A component installed via the seed project can ship its own `component.json` with a `postInstall.modifications` entry that seeds default config files directly into `modifications/base/`. The `bbg-mdf` component is one example where every install copies the component’s default `mdf-app-def.json` over your `bbg-mdf.json`.

During `iocd build`, components are reinstalled first, which triggers this overwrite, and only then are modifications applied. So by the time `applyModifications` runs, you already have the default content in base.

### Why Some Files Survive and Others Don’t

Whether a file in `modifications/base/iocd/config/apps/` gets overwritten on each build depends on the source component. A file is **not** overwritten when the component’s `postInstall.modifications` entry sets `"overwrite": false`.

The `bbg` component, for example, ships with `overwrite: false`:

```auto
{
    "postInstall": {
        "modifications": [
            {
                ...
                "overwrite": false
            }
        ]
    }
}

```

With `overwrite: false`, the seeded default is written only when the destination file doesn’t already exist. Any subsequent install leaves your customized `bbg.json` alone. You may think of setting `overwrite: false`manually in each component, but this will be temporary. `iocd build`, will reinstall components (fresh package files), which restores the original `component.json` without `"overwrite": false`.

* * *

## Solution: Put the Override in a Mode-Specific Folder

Place the authoritative custom config in `modifications/build/` (for builds) and/or `modifications/dev/` (for dev mode):

```auto
modifications/build/iocd/config/apps/bbg-mdf.json # for builds
modifications/dev/iocd/config/apps/bbg-mdf.json # for dev mode

```

When `applyModifications` runs, it applies `modifications/base/` first (seeded default), then applies `modifications/build/` or `modifications/dev/` second, and your custom file overrides the default.

You can leave or delete the file from `modifications/base/` - it will be overwritten by the component install regardless.

## See Also

- [Seed Project — Modifications](https://docs.interop.io/desktop/developers/seed-project/index.html#customization-modifications) - the order in which `modifiations`are applied.

- [Multi-Environment Builds in io.Connect Seed Project](https://community.interop.io/t/multi-environment-builds-in-io-connect-seed-project/577) - patterns for using `modifications/build/` to produce per-environment configurations.