ES module system

I1 requires ECMAScript module semantics, not Node’s resolver, not Bun’s package rules, and not Deno’s URL imports. Host resolution (filesystem, HTTPS, node_modules) is a runtime concern layered on top of language module records.

In scope for I1

Concern	Requirement
Module parse goal	Parse `Module` / `ModuleItem` forms per pin
Module records	Source text module records with requested/imported bindings
Linking	Resolve bindings, handle cycles per spec
Evaluation	Instantiate + evaluate order; TDZ rules
Top-level await	Ordering and capability as required by pin
Import attributes	Support forms required by the pinned edition
`import.meta`	Host hook exists; minimal fields OK if documented
Dynamic `import()`	Returns Promise; integrates with module loader host hooks

Out of scope for I1 (host / later)

Concern	Where it goes
`node_modules` / package.json `exports`	Node-compat / PM
`npm:` / `jsr:` URL schemes	Deno-shaped host
TypeScript / JSX transform before parse	Transform layer (already partial)
Hot module reload	DX / embed (SCR-21 era host work)
CommonJS `require`	Explicit CJS interop later — not ES language

Current scripty state

Item	Status
Local relative ESM load	`partial` — extension probing `.js/.ts/.tsx/.jsx/.mjs` + `index.*`
Cyclic graphs	`unsupported`
TLA	`unsupported`
Import attributes	`unsupported`
Full link algorithm	`partial`

Smokes: testdata/smoke/esm_main.js, testdata/smoke/ts_main.ts (in the scripty repo).

Host loader contract (sketch)

The engine should call a host resolve + load hook:

resolve(specifier, referrer) -> resolved_url
load(resolved_url) -> source_text + module_type

I1 correctness is about what happens after source text is obtained. Host policy (permissions, network, cache) belongs to runtime matrices.

Phase alignment

Phase	Module work
ES-1	Parse import/export forms
ES-3+	Binding / TDZ interactions
ES-8	Full link + evaluate + TLA + attributes
ES-9	Test262 module suite green

Exit criteria

In-scope module Test262 green
Cyclic dependency fixtures pass
Dynamic import() passes in-scope tests
Fail closed on unsupported host resolution schemes (clear error)

Get started

v0.0.1-dev program

I1 — ES Engine

I2 — Bun-exclusive

I3 — Deno-exclusive

Reference

ES module system

ES module system

In scope for I1

Out of scope for I1 (host / later)

Current scripty state

Host loader contract (sketch)

Phase alignment

Exit criteria

​ES module system

​In scope for I1

​Out of scope for I1 (host / later)

​Current scripty state

​Host loader contract (sketch)

​Phase alignment

​Exit criteria

ES module system

In scope for I1

Out of scope for I1 (host / later)

Current scripty state

Host loader contract (sketch)

Phase alignment

Exit criteria