[APPS][Connections Part 5] Move apps Vite behavior into getVitePlugin

[sdkennedy2]

Motivation

build-plugins#353 needs to find action-catalog call sites that are reachable from a *.backend.* entry file, even when the calls are defined in imported helper modules instead of directly inside the backend entry file.

That graph traversal needs more of the Vite/Rollup plugin context available where backend transformation happens: module resolution, module loading, watch-file registration, and eventually TypeScript-to-JavaScript fallback transforms for local modules. Keeping backend transform ownership split between packages/plugins/apps/src/index.ts and getVitePlugin would force the graph PR to thread more Vite-specific state through the top-level apps plugin entrypoint.

This PR isolates that behavior-neutral ownership move first. The follow-up graph PR can then focus on the actual traversal and extraction behavior instead of mixing it with structural movement.

Changes

Moves existing Vite-owned apps plugin behavior into getVitePlugin without changing the connection ID extraction boundary or upload behavior.

getVitePlugin now owns:

• backend .backend.* transform and proxy generation
• runtime injection at InjectPosition.MIDDLE
• backend function registry creation and replacement semantics
• backend build/upload sequencing during closeBundle
• dev-server middleware registration

The top-level apps plugin entrypoint now validates options, checks that the bundler is Vite, and delegates Vite-specific behavior to getVitePlugin. getVitePlugin receives the factory context directly so it can read Vite/build metadata and use the same ownership boundary that the module traversal PR will extend.

The upload/archive/manifest path was also extracted into a focused Vite helper module. That keeps vite/index.ts centered on Vite hook wiring while preserving the existing frontend/backend archive layout, root manifest.json shape, upload errors/warnings, and cleanup behavior.

This remains behavior-neutral: the transform still uses the current entry-only connection ID extraction path, so imported helper modules are not newly analyzed in this PR.

QA Instructions

Automated:

• yarn workspace @dd/apps-plugin typecheck
• yarn workspace @dd/tests test:unit packages/plugins/apps/src/index.test.ts packages/plugins/apps/src/vite/index.test.ts --runInBand
• yarn eslint packages/plugins/apps/src/index.ts packages/plugins/apps/src/vite/index.ts packages/plugins/apps/src/vite/handle-upload.ts packages/plugins/apps/src/index.test.ts packages/plugins/apps/src/vite/index.test.ts --quiet
• git diff --check

Blast Radius

Affects @dd/apps-plugin Vite hook organization only. This PR should preserve generated backend proxies, runtime injection position, backend function registry replacement semantics, upload archive layout, manifest shape, upload cleanup, and dev-server middleware behavior.

The review risk is mostly refactor risk around preserving existing hook timing and upload inputs. New module traversal behavior remains isolated to the child PR.

Documentation

• How to reliably make frontend production changes
• PR Description Guidelines
• Deploy steps

[sdkennedy2]

• [APPS][Connections Part 6] Discover action calls in reachable modules #353
• [APPS][Connections Part 5] Move apps Vite behavior into getVitePlugin #357 👈 (View in Graphite)
• [APPS][Connections Part 4] Resolve same-module connection ID object values #354
• [APPS][Connections Part 3] Resolve same-module connection ID constants #351
• master

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[sdkennedy2]

@codex review
@cursor review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. 👍

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