perf(pi-extension): exact .ts specifiers cut Pi load from 43.5ms to 15ms

[dca123]

Problem

The Pi extension is distributed and executed as raw TypeScript (pi.extensions → index.ts, noEmit) — but its relative import specifiers mix phantom .js paths with extensionless paths. The former name files that never exist in this package; both require jiti to probe instead of resolving the exact file.

Pi's loader (jiti) supports the .js→.ts remap, but only as its last-resort fallback — after two full ESM resolution cascades and three constructed ERR_MODULE_NOT_FOUNDs per import:

jiti 2.7 esmResolve, same file	per resolution
"./config.js" (phantom)	~1,809 µs
"./config.ts" (real file)	~20 µs

Multiplied across the eager import graph it cost me around that's ~26 ms of every Pi session start.

This never shows up in development because Bun does the same remap natively at no cost. startup.test.ts guards the eager-graph shape, but under the one runtime that doesn't exhibit the cost.

Measured result

Extension module import (PI_TIMING=1, n=12 interleaved runs, same machine):

	median
main (.js + extensionless)	43.5 ms
this branch (exact .ts)	15 ms

What changed

1. Hand-written sources: mechanical rewrite of relative .js and extensionless specifiers to exact .ts paths. The tsconfig already fully permits this (moduleResolution: "bundler", noEmit, allowImportingTsExtensions) — zero config changes.
2. vendor.sh: rewrite rules now emit .ts, plus a final normalization pass over generated/ for both .js and extensionless source styles — the monorepo conventions are untouched. It covers import/re-export, dynamic import, and side-effect import forms while leaving bare and explicit non-TypeScript specifiers alone.
3. import-specifiers.test.ts: guards the invariant so future contributions in either style stay correct.

Validation

• bun test — 73/73 (apps/pi-extension), 456/456 (packages/server, which imports these files)
• all seven TypeScript project checks pass
• packed npm artifact audit: 87 generated TypeScript files; all 327 relative specifier occurrences exact; all .ts targets exist
• Scope check: generated/ and the pi-extension sources are consumed only by this package's runtimes (jiti/Bun); the hook, OpenCode, VS Code, and web builds import packages/* directly and see no changed bytes