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David Pine (IEvangelist) merged 2 commits into from
May 5, 2026
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[docs] Document TypeScript validation before AppHost startup #812

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docs: document TypeScript validation before AppHost startup
aspire-repo-bot[bot] May 5, 2026
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Update TypeScript validation section in documentation
sebastienros May 5, 2026
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12 changes: 12 additions & 0 deletions src/frontend/src/content/docs/app-host/typescript-apphost.mdx
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Expand Up @@ -249,6 +249,18 @@ The `aspire doctor` command checks that the required JavaScript toolchain execut
aspire doctor
```

## TypeScript validation before startup

Before starting a TypeScript AppHost, the Aspire CLI runs `tsc --noEmit` to check for type errors to prevent the dashboard and resources from starting in a partially broken state. If your AppHost has TypeScript compile errors, `aspire run` and `aspire publish` stop before the AppHost launches and display the diagnostic output:

```text
apphost.ts(22,7): error TS2322: Type 'string' is not assignable to type 'number'.
```

### Watch mode behavior

When you use `aspire run` in watch mode, the TypeScript validation is embedded in the nodemon restart command. The watcher **can still start** even if there are initial type errors — it will recover automatically as you edit and save files that fix the errors.

## See also

- [Build your first app](/get-started/first-app/?lang=typescript)
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