Adds a test case to `settings.test.ts` to specifically verify
the correct resolution of multiple environment variables concatenated
within a single string value (e.g., ${HOST}:${PORT} ).
Refactors the `resolveEnvVarsInObject` function in settings to
explicitly handle primitive types (null, undefined, boolean, number)
at the beginning of the function. This clarifies the logic for
subsequent string, array, and object processing.
This commit introduces the ability to use system environment variables
within the settings files (e.g., `settings.json`). Users can now
reference environment variables using the `${VAR_NAME}` syntax.
This enhancement improves security and flexibility, particularly
for configurations like MCP server settings, which often require
sensitive tokens.
Previously, to configure an MCP server, a token might be directly
embedded:
```json
"mcpServers": {
"github": {
"env": {
"GITHUB_PERSONAL_ACCESS_TOKEN": "pat_abc123"
}
// ...
}
}
```
With this change, the same configuration can securely reference an
environment variable:
```json
"mcpServers": {
"github": {
"env": {
"GITHUB_PERSONAL_ACCESS_TOKEN": "${GITHUB_PERSONAL_ACCESS_TOKEN}"
}
// ...
}
}
```
This allows users to avoid storing secrets directly in configuration files.
