mcp: Avoid stopping servers for equivalent URI definitions

[Girish Konda (kondv)]

Fixes #327970

Problem

McpServerDefinition.equals uses generic structural equality for URI-bearing fields. A URI stores enumerable lazy caches such as _formatted and _fsPath, so equivalent definitions can compare unequal when only one URI instance has populated a cache. McpService.updateCollectedServers() then treats the equivalent definition as changed and stops the live server.

Change

Compare nested URI values by normalized resource identity while preserving the existing structural comparison behavior for arrays, objects, primitives, inherited enumerable properties, and missing versus explicit undefined values.

The change is scoped to the launch, presentation, and variableReplacement comparisons in McpServerDefinition.equals. Serialization, revival, hashing, and server lifecycle behavior are unchanged.

This shares the URI-cache diagnosis from #329857, but is intentionally narrower. #329857 also changes serialization, revival, hashing, and malformed or cyclic value handling; this PR changes only the in-memory equality used by the reproduced stop path and adds service-level coverage for that path.

Validation

• Node tests: mcpTypes (20 passing), mcpService (3 passing)
• Chromium tests: mcpTypes (19 passing), mcpService (2 passing)
• npm run typecheck-client
• Targeted ESLint and hygiene checks
• Live desktop A/B/C validation with a stateful Streamable HTTP MCP server:
  • VS Code 1.135 and the same Code OSS build with the comparator reverted both sent a session-termination request after an equivalent warm/cold URI republish and logged stopped because the definition changed.
  • The patched Code OSS build kept the original session connected for 60 seconds after the equivalent republish.
  • A genuinely changed URI still stopped the original session; starting the updated definition created a new session.

[Girish Konda (kondv)]

@microsoft-github-policy-service agree company="Microsoft"

[Copilot]

Pull request overview

Fixes MCP server restarts caused by URI lazy-cache differences during definition equality checks.

Changes:

• Adds URI-aware structural comparison for relevant definition fields.
• Adds equality and server lifecycle regression tests.
• Preserves detection of genuine definition changes.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
mcpTypes.ts	Adds URI-aware definition equality.
mcpTypes.test.ts	Covers URI cache and actual-value differences.
mcpService.test.ts	Covers server stop behavior after republishing definitions.

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.