Add TypeScript resolution support to stasis bundle (--typescript, tsconfig paths)

[exo-nikita]

Summary

Adds tsc-style TypeScript resolution to the bundler via a new --typescript flag: specifiers naming compiled output (e.g. import "./x.js") resolve to their on-disk TypeScript sources (./x.ts), the way tsc resolves imports between TS sources, including through package manifests and tsconfig compilerOptions.paths aliases.

Key Changes

• New --typescript flag: retries a failed resolution with tsc's mapping. Fallback-only: an on-disk .js always wins over its .ts twin, and a successful resolution is never rewritten.

• Extension substitution rules:

  • .js → .ts (or .tsx when --jsx is enabled)
  • .jsx → .tsx (only when --jsx is enabled)
  • .mjs → .mts, .cjs → .cts
  • extensionless ./x → ./x.ts, ./dir → ./dir/index.ts (also through a directory's package.json main)
  • type declarations (.d.ts) are never resolution targets

• Manifest coverage: the same substitution applies to package main targets, exports targets, #name imports targets, and bare subpaths into exports-less packages — so an unbuilt TS-source dependency resolves whether it declares main or exports. Exports maps are never widened: an unexported subpath stays unresolved.

• tsconfig paths aliases (e.g. "@/*": ["./src/*"]): consulted for bare specifiers nothing else resolved, from the project root's tsconfig.json when present or an explicit --tsconfig=path. JSONC accepted, extends chains followed (paths replaces wholesale, like tsc), targets resolved against baseUrl (else the declaring config's dir), exact keys beat longest-prefix * patterns. A dependency's own imports never see the app's aliases, and --tsconfig without --typescript is rejected.

• One shared implementation: all tsc-style rules live in the new src/resolve-typescript.js; both resolvers (the built-in Node resolver in scan.js and the legacy-field --mainFields/--metro resolver) complete their misses through the same dispatcher, so the flag behaves identically on every path. '.', '..' and trailing-/ specifiers resolve as directory imports (a literal .ts dotfile can no longer shadow index.ts).

• Statement-level type erasure (verbatimModuleSyntax / Node type-stripping parity): only import type / export type / export type * statements drop their edge; import {}, import { type A }, export { type A } from, and export {} from still load their modules at runtime, so their edges are recorded (previously all-inline-type imports and export {} from lost their edges). Static import/re-export edges now come off the AST, where statement-level importKind/exportKind carries the distinction oxc's module records cannot.

• Validation: rejects --typescript for non-JS entries and with --metro-resolver (which cannot substitute).

Notable Implementation Details

• The recorded edge keeps the original specifier (e.g. ./dep.js, @/dep.js) while the target is the mapped file — stasis run --bundle=load replays the mapping from the import map, so the bundle runs under plain Node with types stripped at load.
• A companion --lockfile attests the mapped targets (the real bytes on disk), never phantom .js outputs.
• Test coverage: unit (sibling table, paths matcher incl. JSONC/extends), resolver-level (both engines, exports/imports/main/subpath/dot-specifier shapes, alias no-hijack rules, the type-erasure matrix), and CLI e2e including a bundle → run --bundle=load round-trip verified against plain Node's load set.

https://claude.ai/code/session_011np6aa8nMXi29WPqD6azHh