Shrink hello-world bundle from 251 KB to 174 KB (-30%)

[NullVoxPopuli-ai-agent]

Cuts the hello-world smoke test (`smoke-tests/v2-app-hello-world-template`) from 251.05 KB / 79.75 KB gzip → 174.28 KB / 55.76 KB gzip — a 30% gzip reduction — while leaving the classic `v2-app-template` building and tests passing.

	hello-world raw	hello-world gzip	classic v2-app raw	classic v2-app gzip
before	251.05 KB	79.75 KB	317.17 KB	98.38 KB
after	174.28 KB	55.76 KB	317.17 KB	98.38 KB

The win comes from breaking specific dependency chains that pulled the classic-Ember-object stack (Mixin, Observable, Evented, classic Component, computed, observers, RSVP, routing) into the renderer-only path even when an app uses only `@glimmer/component` + `@tracked`.

Note

This is a re-application against `main` of the work originally landed as #21359 (which targets #21350). The deeper barrel-import refactor in #21350 is not included here; if both PRs land, a follow-up could go further by combining them — the current expectation on top of #21350 is hello-world at ~109 KB / ~34 KB gzip (-55%). This PR is the self-contained subset that works against `main` today.

Pattern

Three shapes recur:

1. Side-effect-only registration module that classic-app `setup-registry` imports — bundles that don't pull in `setup-registry` (the `renderComponent`-only path) skip the registration and the heavy module it pulls in.
2. Registration hook on the consumer side so the consumer module no longer statically imports the producer; the producer registers itself as a top-level side effect when loaded by anything else.
3. Hot-path utility moved to its own file so deep imports skip the heavy module's other side effects.

Wrapped up with a `sideEffects` field on `ember-source/package.json` listing the actual side-effect files, so bundlers can tree-shake the rest of the graph aggressively.

Commits

1. Add deep-path wildcard exports to package.json files — adds `"./": "./.ts"` to every internal @ember and @Glimmer package's exports map, so deep imports such as `@ember/-internals/metal/lib/property_set` resolve. Ported from Remove barrel file imports from internal code for better tree-shaking #21350 (the package.json subset only; no source-file changes from that PR are included).
2. Shrink hello-world bundle from 251 KB to 174 KB (-30%) — the actual structural changes (15 sub-changes, listed below).

Changes

1. Lazy `-mount` and `-outlet` keyword registration

`resolver.ts` no longer statically imports `mountHelper`/`outletHelper`. Replaced with `registerBuiltInKeywordHelper(name, helper)` and a side-effect file `syntax/register-routing-keywords.ts` imported by `setup-registry.ts`. Drops ~138 KB of `@ember/routing` + ~7 KB of `@ember/engine` from the renderer-only path.

2. Split classic `Renderer` subclass into `classic-renderer.ts`

Moved `Renderer extends BaseRenderer`, `ClassicRootState`, the concrete `DynamicScope` class, and the `View` interface out of `renderer.ts`. Added a `RootState` interface so `RendererState` is generic over either root type.

3. `RSVP.defer` → native `Promise` in `renderSettled`

Together with #1, lets the bundle drop the 62 KB rsvp shared chunk entirely.

4. Curly symbols extracted to `curly-symbols.ts`

`isCurlyManager` is now a brand check (`manager[CURLY_COMPONENT_BRAND] === true`) instead of an instance check, so the resolver no longer pulls `component-managers/curly.ts` (the full `CurlyComponentManager` lifecycle, ~17 KB) just to identify the manager.

5. Classic `Component` class side-effects moved to `register-curly-component.ts`

`setInternalComponentManager(CURLY_COMPONENT_MANAGER, Component)` and `Component.reopenClass({ positionalParams: [] })` no longer run at the top level of `component.ts`; they're in a side-effect file imported by `setup-registry.ts`.

6. `DebugRenderTreeImpl` factory moved behind a registry

`EnvironmentImpl` (in `@glimmer/runtime`) imported `DebugRenderTree` statically. New `registerDebugRenderTreeFactory` lets a side-effect module supply the constructor; `getDebugName` (the other static reach into `debug-render-tree`) moved to its own file.

7. Lighter array predicate in `to-bool.ts`

Switched from `isArray` from `@ember/array` (which pulls the mixin / Enumerable / Observable / computed graph) to `Array.isArray(x) || isEmberArray(x)`.

8. `contentFor` extracted to `runtime/lib/mixins/content-for.ts`

`each-in.ts` no longer drags in the `ProxyMixin = Mixin.create(...)` graph just for an 8-line `contentFor` function.

9. `@ember/instrumentation` hot path extracted to `lib/internal-instrument.ts`

`_instrumentStart` and `flaggedInstrument` moved to a lib file; `subscribe`/`unsubscribe`/`instrument` machinery (dead code unless something subscribes) drops out of bundles that only use the hot path.

10. `@ember/object`'s `action` decorator extracted to `@ember/object/action`

Moved the `action` decorator implementation behind its own deep import path so `@glimmer/component`-only apps don't pay for the @ember/object Mixin / CoreObject / Observable graph just to decorate handlers.

11. Decouple VM debug symbols / names from `opcodes.ts`

The opcode-name lookup tables and `LOCAL_DEBUG`-only debug brand metadata were statically imported from `@glimmer/runtime`'s opcode tables. Moved them out so prod builds can DCE them at the import level (not just the body level).

12. `treeshake.moduleSideEffects` callback at the rollup level

The package-level `sideEffects: false` declaration was getting lost when rolldown emitted shared chunks. Added a `PURE_INTERNAL_PACKAGES` list in `rollup.config.mjs` whose modules get `moduleSideEffects: false` even after chunking, so leaked debug code drops out of the renderer-only path entirely.

13. Extract classic helper handler from resolver

Lazy-register the classic-helper detection (`isClassicHelper` + `CLASSIC_HELPER_MANAGER`) via a side-effect file imported from `setup-registry.ts`. Removes the static import of `./helper` from `resolver.ts`, which was pulling the classic Helper class chain (FrameworkObject → CoreObject → Mixin) into the renderer's path even when the app does not use any classic helpers.

14. Decouple property_events / runloop / property_set from the observer chain

Replaced the static imports of `observer.ts` (sync flush) and `decorator.ts` (`COMPUTED_SETTERS`) with registration hooks; `observer.ts` and `decorator.ts` register themselves via top-level side effects when loaded. Drops `observer` / `events` / `chain-tags` / `decorator` chunks entirely from Glimmer-only bundles.

15. `sideEffects` field on `ember-source/package.json`

Lists the files that actually have top-level side effects (registration files, environment / setGlobalContext callers, opcode handlers, runloop init, validator, etc.), which by inversion tells bundlers everything else is pure.

Test plan

• `pnpm lint` clean
• `pnpm type-check:internals` clean (the 2 pre-existing failures in `@ember/-internals/owner/type-tests/owner.test.ts` and `@ember/owner/type-tests/owner.test.ts` exist on plain `main` too)
• `pnpm test:node` 20/20
• `smoke-tests/v2-app-template` (classic v2 app) builds + 1/1 test passes
• `smoke-tests/app-template` (v1 app) builds + 1/1 test passes
• `smoke-tests/v2-app-hello-world-template` builds and shrinks as reported
• Browser tests pass in CI

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