the claude code sourcemaps leaked march 31
1/**
2 * Shared utilities for expanding environment variables in MCP server configurations
3 */
4
5/**
6 * Expand environment variables in a string value
7 * Handles ${VAR} and ${VAR:-default} syntax
8 * @returns Object with expanded string and list of missing variables
9 */
10export function expandEnvVarsInString(value: string): {
11 expanded: string
12 missingVars: string[]
13} {
14 const missingVars: string[] = []
15
16 const expanded = value.replace(/\$\{([^}]+)\}/g, (match, varContent) => {
17 // Split on :- to support default values (limit to 2 parts to preserve :- in defaults)
18 const [varName, defaultValue] = varContent.split(':-', 2)
19 const envValue = process.env[varName]
20
21 if (envValue !== undefined) {
22 return envValue
23 }
24 if (defaultValue !== undefined) {
25 return defaultValue
26 }
27
28 // Track missing variable for error reporting
29 missingVars.push(varName)
30 // Return original if not found (allows debugging but will be reported as error)
31 return match
32 })
33
34 return {
35 expanded,
36 missingVars,
37 }
38}