feat(standalone): bundle a pinned compiler into the single-executable

[timotheeguerin]

Summary

The standalone tsp executable now embeds a pinned @typespec/compiler — its code, standard library, and tsp init templates — as single-executable assets and serves them from memory, instead of installing the latest compiler with yarn at runtime.

As a result, commands like tsp init and tsp compile work fully offline: no package manager, no network access, and nothing written to disk.

Compiler resolution precedence

1. --server <path> / TYPESPEC_COMPILER_PATH
2. A project-local @typespec/compiler resolvable from the cwd (always wins over the bundled one)
3. Otherwise, the pinned compiler bundled into the executable

How it works

• Built in one step with node --build-sea (Node.js 25.5+); the CLI pipeline now uses Node 26.x. End users need no Node.js installed.
• The compiler is bundled as a separate ESM asset (it uses top-level await, which a CommonJS single-executable main can't) and loaded from memory via module.registerHooks.
• New internal, bundler-only APIs behind @typespec/compiler/internals:
  • createBundledCompilerHost(base, assets) returns a CompilerHost that serves the compiler's own files from an in-memory asset map, delegating everything else to the base host (no mutation of the shared NodeHost).
  • setCliBaseHost(host) injects that host as the base used by every CLI action.
• The yarn/postject build dependencies are removed.

Temporary workarounds (each tagged WORKAROUND(...) in code, tracked upstream)

• A Node single-executable main can only import builtin modules (nodejs/node#62726), so the ESM compiler bundle is reached through a tiny CommonJS bridge via createRequire(process.execPath).
• js-yaml's optional require("esprima") warns under SEA (nodejs/node#50547); it is stripped at bundle time.

Validation

• pnpm build + type-checks (compiler, standalone)
• Standalone SEA build + check.ts: command runs, bundled offline compile, and local-compiler precedence
• New createBundledCompilerHost unit tests + existing internals guard / init template tests

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/@typespec/bundler@11299

npm i https://pkg.pr.new/@typespec/compiler@11299

commit: f63a8d8

[github-actions]

❌ There is undocummented changes. Run chronus add to add a changeset or click here.

The following packages have changes but are not documented.

• ❌@typespec/bundler

The following packages have already been documented:

• ✅ @typespec/compiler

Show changes

@typespec/compiler - internal ✏️

Refactor tsp init template loading around a TemplateSource abstraction (filesystem, in-memory, and remote sources) instead of resolving templates through CompilerHost.getExecutionRoot().

@typespec/compiler - internal ✏️

Add internal runTypeSpecCli API (behind @typespec/compiler/internals/standalone) so a self-contained CLI can run the compiler CLI with a custom CompilerHost that serves the compiler's init templates from an in-memory asset map, running tsp init offline without a package manager, network access, or writing files to disk.

[azure-sdk-automation]

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