mcp: replace repeated variable placeholders in config values

[bharatvansh]

Summary

Fixes placeholder interpolation for MCP manifest values when the same variable appears multiple times in a single string.

Previously, interpolation used single-replacement behavior, so only the first {variable} occurrence was converted to ${input:variable}. This left subsequent occurrences unresolved.

Changes

• Add replaceInputVariableReference(value, variableId) helper in mcpManagementService.ts.
• Use the helper in all variable interpolation paths:
  • key/value inputs (env + remote headers)
  • positional arguments
  • named arguments
• Add regression tests for repeated placeholders in:
  • environment values
  • argument values

Example

Bearer {api_token}:{api_token} now becomes:
Bearer ${input:api_token}:${input:api_token}

Validation

• npm run transpile-client ✅
• scripts/test.bat --grep "McpManagementService - getMcpServerConfigurationFromManifest" ✅ (37 passing)

[Copilot]

Pull request overview

This PR fixes MCP manifest placeholder interpolation so that all occurrences of a {variable} placeholder in a single string are replaced (not just the first), ensuring generated ${input:...} references are complete across MCP configuration parsing.

Changes:

• Introduces a replaceInputVariableReference(value, variableId) helper to replace repeated {variableId} placeholders.
• Applies the helper across all interpolation paths (key/value inputs and arguments).
• Adds regression tests covering repeated placeholders in env values and named argument values.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/vs/platform/mcp/common/mcpManagementService.ts	Centralizes placeholder replacement into a helper and uses it in key/value input and argument processing.
src/vs/platform/mcp/test/common/mcpManagementService.test.ts	Adds regression tests to ensure repeated placeholders are fully replaced in env and argument strings.

[Copilot]

The new interpolation helper is used for key/value inputs (including remote headers) and positional args too, but the added regression tests only cover env values and a named argument. Please add at least one test that exercises repeated placeholders in a remote header value and one for a positional argument value, so the full intended behavior is protected against regressions.