Dead code: getSystemFragment is defined but never called

[PewterZz]

Summary

getSystemFragment in src/proxy.ts:115-149 is a complete HTTP fetcher with cache + TTL + timeout, but nothing in the binary calls it. Only the definition shows up across the repo.

Evidence

$ grep -n getSystemFragment src/proxy.ts
115:async function getSystemFragment(baseUrl: string, token: string): Promise<string> {

No callers anywhere. The supporting state (_systemFragmentCache, _systemFragmentFetchedAt, FRAGMENT_TTL_MS) is likewise untouched after its initial assignment.

Why it matters

• Confuses auditors reading the proxy — the README promotes the binary as thin, but this function suggests a whole fragment-fetch code path that doesn't run.
• Drags along a TTL constant + two module-level lets that exist for one call site that never happens.

Fix options

1. Delete — if the server-side /prepare endpoint already returns system_fragment (it does, see PrepareResult.system_fragment at src/proxy.ts:408), the client doesn't need its own fetcher. Remove the function and the cache globals.
2. Wire up — if there was a planned fallback (fetch fragment when /prepare is skipped / passthrough), call it from handleRequest explicitly and document when.

My read: option 1 is correct. The prepare exchange is the only content-aware call the proxy makes, per the README.