Codegen: --vscode-extension flag to inline extraImports wiring

[hyperpolymath]

Problem

The Node-CJS codegen (lib/codegen_node.ml, added by #35 / #90) emits a .cjs shim that wraps the compiled wasm module. The shim exposes an extraImports hook that callers populate with the concrete vscode-API bindings before activate fires:

// Inside the generated extension.cjs:
const extras = (typeof exports.extraImports === "function")
    ? exports.extraImports()
    : {};
return { wasi_snapshot_preview1, ...extras };

Today, every consumer hand-writes a wrapper file to install extraImports before vscode's extension host calls activate. The pattern is identical across the three current consumers:

// hyperpolymath/my-lang:vscode-extension/src/index.cjs
// hyperpolymath/standards:rsr-certifier/extensions/vscode/src/index.cjs
// hyperpolymath/affinescript:editors/vscode/src/index.cjs  (still to land)

const shim = require("../out/extension.cjs");
const makeVscodeBindings = require("./affine-vscode-adapter.cjs");
// or: const makeVscodeBindings = require("@hyperpolymath/affine-vscode");

shim.extraImports = () => makeVscodeBindings(
    require("vscode"),
    require("vscode-languageclient/node"),
    shim,
);

exports.activate = shim.activate;
exports.deactivate = shim.deactivate;

This boilerplate is 100% mechanical and identical in every extension. It's what's left to manually wire — and it's the thing #35's original plan called out as belonging in codegen:

(Real wiring belongs in the codegen — Phase 3 will replace this manual hookup with auto-generated glue once extension.affine is the source of truth for the extension entry point.)

— packages/affine-vscode/README.adoc

Proposed plan

Add a codegen flag, e.g. --vscode-extension, that opts into emitting the wiring inline so the generated .cjs is directly loadable as a VS Code extension's main:

affinescript compile src/extension.affine -o out/extension.cjs --vscode-extension

The emitted shim then includes the equivalent of:

// Inserted by --vscode-extension:
const makeVscodeBindings = require("@hyperpolymath/affine-vscode");
exports.extraImports = function() {
  return makeVscodeBindings(
    require("vscode"),
    require("vscode-languageclient/node"),
    exports,
  );
};

… with @hyperpolymath/affine-vscode listed in the extension's package.json dependencies. (Once the npm-publish follow-up lands — see the sibling follow-up issue — this is a normal npm install.)

Each consumer's package.json main then points directly at out/extension.cjs. No hand-written index.cjs, no vendored affine-vscode-adapter.cjs file.

Sub-flags

• --vscode-extension-adapter <module-specifier> — override the require() specifier for the adapter (useful for testing against a local checkout or for extensions that vendor their own).
• --vscode-extension-no-lc — for extensions that don't ship a language client (no vscode-languageclient/node dependency); the wiring skips that require and passes null.

Acceptance criteria

• affinescript compile src/extension.affine -o out/extension.cjs --vscode-extension emits a fully-wired CJS module.
• A VS Code extension whose package.json main points at the unmodified generated .cjs activates and disposes cleanly.
• The pilot in editors/vscode/ is migrated off the hand-written index.cjs (once that wrapper exists; this work and the affinescript-pilot port in [Repo] Port editors/vscode/src/extension.ts to .affine once #35 lands #63 likely coordinate).
• my-lang and standards downstream PRs simplify accordingly (their index.cjs + vendored adapter both disappear).
• Codegen tests cover the --vscode-extension flag.

Out of scope

• A general --vscode-target-language-server-extension shape for extensions that aren't language-server-shaped. This issue covers the LSP+commands pattern that the current adapter implements.
• A browser-host webworker variant (Node-only for now).

Related

• Codegen origin: Add Node-target backend + vscode-API bindings to enable .affine VS Code extensions #35 (Phase 1 + Phase 2), feat: typed-wasm xmod + Node backend + extern + VS Code (#35, #42) #90 (PR)
• Phase-2 hook the boilerplate lives around: see _buildImports() in the emitted .cjs
• Consumer pattern that this would eliminate:
  • hyperpolymath/my-lang#11
  • hyperpolymath/standards#46
• Related follow-up: npm-publishing the adapter (sibling issue) is a prerequisite for the default require("@hyperpolymath/affine-vscode") to resolve in consumer projects.