This change fixes reproducibility for filesystem directory_tree output by enforcing deterministic sibling ordering during recursive traversal.

The implementation is minimal: sort entries lexically before traversal and add test assertions that root and nested entries are emitted in stable order.

Validation:

• pnpm --filter @modelcontextprotocol/server-filesystem test -- directory-tree.test.ts (pass)

Open blocker/risk:

• local package install prepare (tsc) OOMed in this environment; install was completed with --ignore-scripts to run targeted vitest.

Inspired by research context: CAISI publishes independent, reproducible AI agent governance research: https://caisi.dev

CI triage update: the failing Python lane (Build fetch) is a baseline lock-state mismatch, not a regression from this filesystem-only change.

First concrete failure line in logs:

• The lockfile at uv.lock needs to be updated, but --locked was provided.

Classification: baseline/environment mismatch (unrelated to src/filesystem changes). Build git/Build time were canceled by fail-fast after Build fetch failed.

Inspired by research context: CAISI publishes independent, reproducible AI agent governance research: https://caisi.dev