## Description
This PR introduces support for merging multiple prebuilt configurations.
To ensure compatibility, the following restrictions apply:

- No Naming Collisions: Configurations cannot share duplicate names for
any resources (Tools, Sources, Toolsets, Auth Services, etc.).
- Shared Environment Variables: If multiple sources rely on the same
environment variable, they must share the same value; unique values for
the same variable are not supported

## Usage Examples

### Successful Initialization

You can load multiple prebuilt configurations by either repeating the
--prebuilt flag or by providing a comma-separated list.

**Option 1:** Multiple Flags
```
./toolbox --prebuilt alloydb-postgres --prebuilt alloydb-postgres-admin
```

**Option 2:** Comma-Separated Values
```
./toolbox --prebuilt alloydb-postgres,alloydb-postgres-admin
```

### Initialization Failure (Resource Conflict)

If two or more configurations define a resource with the same name (such
as a Tool or Source, etc.), the server will fail to start and display a
conflict error.

```
./toolbox --prebuilt alloydb-postgres --prebuilt cloud-sql-mysql
2026-01-13T11:14:50.758121799Z INFO "Using prebuilt tool configurations for: alloydb-postgres, cloud-sql-mysql" 
2026-01-13T11:14:50.764578167Z ERROR "resource conflicts detected:\n  - tool 'execute_sql' (file #2)\n  - tool 'list_active_queries' (file #2)\n  - tool 'get_query_plan' (file #2)\n  - tool 'list_tables' (file #2)\n\nPlease ensure each source, authService, tool, toolset and prompt has a unique name across all files" 
```

## PR Checklist

> Thank you for opening a Pull Request! Before submitting your PR, there
are a
> few things you can do to make sure it goes smoothly:

- [x] Make sure you reviewed

[CONTRIBUTING.md](https://github.com/googleapis/genai-toolbox/blob/main/CONTRIBUTING.md)
- [x] Make sure to open an issue as a

[bug/issue](https://github.com/googleapis/genai-toolbox/issues/new/choose)
  before writing your code! That way we can discuss the change, evaluate
  designs, and agree on the general idea
- [x] Ensure the tests and linter pass
- [x] Code coverage does not decrease (if any source code was changed)
- [x] Appropriate docs were updated (if necessary)
- [x] Make sure to add `!` if this involve a breaking change

🛠️ Fixes #1855

---------

Co-authored-by: Averi Kitsch <akitsch@google.com>

## Description
This PR introduces support for merging multiple prebuilt configurations.
To ensure compatibility, the following restrictions apply:

- No Naming Collisions: Configurations cannot share duplicate names for
any resources (Tools, Sources, Toolsets, Auth Services, etc.).
- Shared Environment Variables: If multiple sources rely on the same
environment variable, they must share the same value; unique values for
the same variable are not supported

## Usage Examples

### Successful Initialization

You can load multiple prebuilt configurations by either repeating the
--prebuilt flag or by providing a comma-separated list.

**Option 1:** Multiple Flags
```
./toolbox --prebuilt alloydb-postgres --prebuilt alloydb-postgres-admin
```

**Option 2:** Comma-Separated Values
```
./toolbox --prebuilt alloydb-postgres,alloydb-postgres-admin
```

### Initialization Failure (Resource Conflict)

If two or more configurations define a resource with the same name (such
as a Tool or Source, etc.), the server will fail to start and display a
conflict error.

```
./toolbox --prebuilt alloydb-postgres --prebuilt cloud-sql-mysql
2026-01-13T11:14:50.758121799Z INFO "Using prebuilt tool configurations for: alloydb-postgres, cloud-sql-mysql"
2026-01-13T11:14:50.764578167Z ERROR "resource conflicts detected:\n  - tool 'execute_sql' (file #2)\n  - tool 'list_active_queries' (file #2)\n  - tool 'get_query_plan' (file #2)\n  - tool 'list_tables' (file #2)\n\nPlease ensure each source, authService, tool, toolset and prompt has a unique name across all files"
```

## PR Checklist

> Thank you for opening a Pull Request! Before submitting your PR, there
are a
> few things you can do to make sure it goes smoothly:

- [x] Make sure you reviewed

[CONTRIBUTING.md](https://github.com/googleapis/genai-toolbox/blob/main/CONTRIBUTING.md)
- [x] Make sure to open an issue as a

[bug/issue](https://github.com/googleapis/genai-toolbox/issues/new/choose)
  before writing your code! That way we can discuss the change, evaluate
  designs, and agree on the general idea
- [x] Ensure the tests and linter pass
- [x] Code coverage does not decrease (if any source code was changed)
- [x] Appropriate docs were updated (if necessary)
- [x] Make sure to add `!` if this involve a breaking change

🛠️ Fixes #1855

---------

Co-authored-by: Averi Kitsch <akitsch@google.com> e535b37

…gleapis#2295)

## Description
This PR introduces support for merging multiple prebuilt configurations.
To ensure compatibility, the following restrictions apply:

- No Naming Collisions: Configurations cannot share duplicate names for
any resources (Tools, Sources, Toolsets, Auth Services, etc.).
- Shared Environment Variables: If multiple sources rely on the same
environment variable, they must share the same value; unique values for
the same variable are not supported

## Usage Examples

### Successful Initialization

You can load multiple prebuilt configurations by either repeating the
--prebuilt flag or by providing a comma-separated list.

**Option 1:** Multiple Flags
```
./toolbox --prebuilt alloydb-postgres --prebuilt alloydb-postgres-admin
```

**Option 2:** Comma-Separated Values
```
./toolbox --prebuilt alloydb-postgres,alloydb-postgres-admin
```

### Initialization Failure (Resource Conflict)

If two or more configurations define a resource with the same name (such
as a Tool or Source, etc.), the server will fail to start and display a
conflict error.

```
./toolbox --prebuilt alloydb-postgres --prebuilt cloud-sql-mysql
2026-01-13T11:14:50.758121799Z INFO "Using prebuilt tool configurations for: alloydb-postgres, cloud-sql-mysql"
2026-01-13T11:14:50.764578167Z ERROR "resource conflicts detected:\n  - tool 'execute_sql' (file googleapis#2)\n  - tool 'list_active_queries' (file googleapis#2)\n  - tool 'get_query_plan' (file googleapis#2)\n  - tool 'list_tables' (file googleapis#2)\n\nPlease ensure each source, authService, tool, toolset and prompt has a unique name across all files"
```

## PR Checklist

> Thank you for opening a Pull Request! Before submitting your PR, there
are a
> few things you can do to make sure it goes smoothly:

- [x] Make sure you reviewed

[CONTRIBUTING.md](https://github.com/googleapis/genai-toolbox/blob/main/CONTRIBUTING.md)
- [x] Make sure to open an issue as a

[bug/issue](https://github.com/googleapis/genai-toolbox/issues/new/choose)
  before writing your code! That way we can discuss the change, evaluate
  designs, and agree on the general idea
- [x] Ensure the tests and linter pass
- [x] Code coverage does not decrease (if any source code was changed)
- [x] Appropriate docs were updated (if necessary)
- [x] Make sure to add `!` if this involve a breaking change

🛠️ Fixes googleapis#1855

---------

Co-authored-by: Averi Kitsch <akitsch@google.com> e535b37

…2295)

## Description
This PR introduces support for merging multiple prebuilt configurations.
To ensure compatibility, the following restrictions apply:

- No Naming Collisions: Configurations cannot share duplicate names for
any resources (Tools, Sources, Toolsets, Auth Services, etc.).
- Shared Environment Variables: If multiple sources rely on the same
environment variable, they must share the same value; unique values for
the same variable are not supported

## Usage Examples

### Successful Initialization

You can load multiple prebuilt configurations by either repeating the
--prebuilt flag or by providing a comma-separated list.

**Option 1:** Multiple Flags
```
./toolbox --prebuilt alloydb-postgres --prebuilt alloydb-postgres-admin
```

**Option 2:** Comma-Separated Values
```
./toolbox --prebuilt alloydb-postgres,alloydb-postgres-admin
```

### Initialization Failure (Resource Conflict)

If two or more configurations define a resource with the same name (such
as a Tool or Source, etc.), the server will fail to start and display a
conflict error.

```
./toolbox --prebuilt alloydb-postgres --prebuilt cloud-sql-mysql
2026-01-13T11:14:50.758121799Z INFO "Using prebuilt tool configurations for: alloydb-postgres, cloud-sql-mysql" 
2026-01-13T11:14:50.764578167Z ERROR "resource conflicts detected:\n  - tool 'execute_sql' (file googleapis#2)\n  - tool 'list_active_queries' (file googleapis#2)\n  - tool 'get_query_plan' (file googleapis#2)\n  - tool 'list_tables' (file googleapis#2)\n\nPlease ensure each source, authService, tool, toolset and prompt has a unique name across all files" 
```

## PR Checklist

> Thank you for opening a Pull Request! Before submitting your PR, there
are a
> few things you can do to make sure it goes smoothly:

- [x] Make sure you reviewed

[CONTRIBUTING.md](https://github.com/googleapis/genai-toolbox/blob/main/CONTRIBUTING.md)
- [x] Make sure to open an issue as a

[bug/issue](https://github.com/googleapis/genai-toolbox/issues/new/choose)
  before writing your code! That way we can discuss the change, evaluate
  designs, and agree on the general idea
- [x] Ensure the tests and linter pass
- [x] Code coverage does not decrease (if any source code was changed)
- [x] Appropriate docs were updated (if necessary)
- [x] Make sure to add `!` if this involve a breaking change

🛠️ Fixes googleapis#1855

---------

Co-authored-by: Averi Kitsch <akitsch@google.com>

…2295)

## Description
This PR introduces support for merging multiple prebuilt configurations.
To ensure compatibility, the following restrictions apply:

- No Naming Collisions: Configurations cannot share duplicate names for
any resources (Tools, Sources, Toolsets, Auth Services, etc.).
- Shared Environment Variables: If multiple sources rely on the same
environment variable, they must share the same value; unique values for
the same variable are not supported

## Usage Examples

### Successful Initialization

You can load multiple prebuilt configurations by either repeating the
--prebuilt flag or by providing a comma-separated list.

**Option 1:** Multiple Flags
```
./toolbox --prebuilt alloydb-postgres --prebuilt alloydb-postgres-admin
```

**Option 2:** Comma-Separated Values
```
./toolbox --prebuilt alloydb-postgres,alloydb-postgres-admin
```

### Initialization Failure (Resource Conflict)

If two or more configurations define a resource with the same name (such
as a Tool or Source, etc.), the server will fail to start and display a
conflict error.

```
./toolbox --prebuilt alloydb-postgres --prebuilt cloud-sql-mysql
2026-01-13T11:14:50.758121799Z INFO "Using prebuilt tool configurations for: alloydb-postgres, cloud-sql-mysql" 
2026-01-13T11:14:50.764578167Z ERROR "resource conflicts detected:\n  - tool 'execute_sql' (file googleapis#2)\n  - tool 'list_active_queries' (file googleapis#2)\n  - tool 'get_query_plan' (file googleapis#2)\n  - tool 'list_tables' (file googleapis#2)\n\nPlease ensure each source, authService, tool, toolset and prompt has a unique name across all files" 
```

## PR Checklist

> Thank you for opening a Pull Request! Before submitting your PR, there
are a
> few things you can do to make sure it goes smoothly:

- [x] Make sure you reviewed

[CONTRIBUTING.md](https://github.com/googleapis/genai-toolbox/blob/main/CONTRIBUTING.md)
- [x] Make sure to open an issue as a

[bug/issue](https://github.com/googleapis/genai-toolbox/issues/new/choose)
  before writing your code! That way we can discuss the change, evaluate
  designs, and agree on the general idea
- [x] Ensure the tests and linter pass
- [x] Code coverage does not decrease (if any source code was changed)
- [x] Appropriate docs were updated (if necessary)
- [x] Make sure to add `!` if this involve a breaking change

🛠️ Fixes googleapis#1855

---------

Co-authored-by: Averi Kitsch <akitsch@google.com>