Function strip_project_to_js 

pub fn strip_project_to_js(
    out: ProjectOutput,
) -> Result<ProjectOutput, StripError>

Rewrite a compiled ProjectOutput from TypeScript into a JavaScript artefact (the in-browser track’s first-class JS output — ADR 0137). The emitter always produces TypeScript; a JS artefact is that same output with types stripped, which is total because the emitter is strip-only (ADR 0136).

Every .ts module is type-stripped and renamed to .js; the tsconfig.json is dropped (a TypeScript-compiler config with no role for a JS artefact); any other file (e.g. wrangler.toml) passes through unchanged. Source maps and the debug sidecar are dropped — they map into the .ts the JS replaces. Import specifiers are already .js (the default ImportExt), so the renamed tree resolves as-is.