Compiler roots and lifecycle handoffs fail across Angular compilation modes and Vite versions #2518

Please provide the environment you discovered this bug in.

• Analog: 3.0.0-alpha.86, upstream alpha at 4225f45090a4cf4bdfb562a788e908787b6ec73c.
• Reproduced locally on Linux with Node 24.15.0 and pnpm 10.33.0.
• Base workspace: Angular compiler 22.0.0, Vite 8.0.8, Vitest 4.1.4.
• Reproduction commit containing tests against the unchanged implementation.

git clone --branch fix/compiler-vite-compat https://github.com/benpsnyder/analog.git analog-compiler-repro
cd analog-compiler-repro
git checkout 5277af9f7547e95cc4cebaec9cb05085a23e8647
pnpm install --frozen-lockfile --ignore-scripts
NX_DAEMON=false NX_NO_CLOUD=true pnpm exec nx test vite-plugin-angular --testFiles=src/lib/compiler-roots.spec.ts --watch=false --skipNxCache

Use Node 24.15.0 for these commands. --ignore-scripts avoids the workspace-wide prepare build; the focused test builds its own temporary library. No hosted application or credentials are required.

Which area/package is the issue in?

vite-plugin-angular, with the shared package declaration emitter as supporting build infrastructure.

Description

This is the dedicated compiler workstream requested in Brandon's review of analogjs/analog#2516. It separates compiler behavior and compatibility from the workspace/Vitest upgrade, platform SSR, server-function transport, Query lifetimes, and streaming work.

The smallest consumer example is a Vite library that replaces a component file with one outside the original TypeScript roots:

angular({
  tsconfig: 'tsconfig.json',
  jit: false,
  fileReplacements: [
    { replace: 'src/original.ts', with: 'src/replacement.ts' },
  ],
});

When tsconfig.json includes only the original configured entry, the replacement must still be part of Angular's program. The real-build regression instead receives JavaScript with __decorate and the original Component decorator, without defineComponent: compilation fell through to a generic TypeScript transform. The experimental Compilation API also loses integration-provided roots.

The focused tests expose related handoff failures:

Additional focused tests can be selected with:

NX_DAEMON=false NX_NO_CLOUD=true pnpm exec nx test vite-plugin-angular --testFiles=src/lib/compilation-api/compilation-api-plugin.spec.ts,src/lib/analog-plugin-interop.spec.ts,src/lib/oxc-dts-plugin.spec.ts --watch=false --skipNxCache

Please provide the exception or error you saw

TypeError: Cannot set property isSelfAccepting of #<Object> which has only a getter
AssertionError: expected undefined to match object { code: 'export const value = 1;' }
AssertionError: expected declaration output containing 'first?: boolean' to contain 'second?: string'
TS5051: Option 'inlineSources' can only be used when either '--inlineSourceMap' or '--sourceMap' is provided.

Other information

Implementation is published in analogjs/analog#2520, targeting alpha. Current head e767273de6e3b8589b39c815ccdae4db1a6b7e62 passes the compiler/conformance matrix, nine installed Angular/Vite consumer jobs, browser HMR, Windows, and main CI. The PR documents its tested compilation modes, examples, and shared route-policy prerequisite. The reproduction above remains pinned to the original failing implementation; this issue stays open pending merge.

Acceptance criteria for the focused PR:

• Preserve normal compilation and explicitly test the experimental option enabled and disabled.
• Verify test/watch behavior and externally owned Astro transformer cleanup.
• Exercise actual installed packages with Vite 6, 7, and 8 and supported Angular versions, alongside compiler conformance/API tests.
• Verify normal and fast full/partial compilation, compiler roots, emitted JavaScript, and repeated declaration builds.
• Make unavailable experimental APIs fail during configuration with an actionable diagnostic; do not infer availability from the Angular version alone.
• Include the reproduction, package typecheck/build/lint tests, compatibility CI, and concise documentation in this PR.

The workspace/Vitest 5 migration continues separately in analogjs/analog#2508. The environment and failure evidence above describe the pinned baseline; current compatibility results are recorded in the linked compiler PR.

I would be willing to submit a PR to fix this issue

• Yes

Prepared with OpenAI Codex; findings were checked against local source and executable regressions.