feat(frontend): add serverless check when editing the runner config

[jog1t]

Description

Please include a summary of the changes and the related issue. Please also include relevant motivation and context.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[railway-app]

🚅 Deployed to the rivet-pr-4961 environment in rivet-frontend

Service	Status	Web	Updated (UTC)
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frontend-cloud	❌ Build Failed (View Logs)	Web	May 5, 2026 at 6:19 pm
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[jog1t]

• chore: regenerate sdk #4964
• feat(frontend): add serverless check when editing the runner config #4961 👈 (View in Graphite)
• main

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[claude]

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PR Review: feat(frontend): add serverless check when editing the runner config

Overview

This PR adds runtime mode switching (serverless vs serverfull/Runners) to the runner config edit dialogs, along with real-time endpoint health checks for serverless configurations. Key additions:

• A mode toggle (serverless vs. serverfull) in both shared and per-datacenter settings forms
• A health indicator widget that polls the configured runner endpoint and blocks save when the endpoint is unreachable
• A mode-switch confirmation flow that warns when saving would change an existing datacenter runtime mode
• Splits formSchema into baseFormSchema + a superRefine so URL validation only triggers in serverless mode

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Positive aspects

• EndpointHealthCheckProvider / context approach is clean: a single provider scoped to the dialog coordinates all per-field indicators without prop drilling.
• ResetOnModeChange is a focused, reusable side-effect component rather than an ad-hoc useEffect scattered through parent forms.
• ConfirmableSaveButton inline confirmation is a good pattern for preventing accidental mode switches.
• dcSignatureWithoutMetadata fixes a latent bug where metadata diffs were falsely breaking the shared-settings check.
• Debouncing endpoint + headers before firing the health query avoids flooding the API on every keystroke.

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Issues and suggestions

Code style: import order

The SERVERLESS_FIELDS constant is declared between two import blocks, which violates the convention of keeping all imports at the top of the file. Per CLAUDE.md: always add imports at the top of the file. Module-level constants should follow all imports, not be interleaved with them.

validateRuntimeModeFields / submit handler inconsistency

The submit handler in DatacenterSettingsForm uses if (mode === 'serverless' || !mode) treating undefined as serverless and building a serverless config object that requires a URL. But validateRuntimeModeFields checks if (data.mode === 'serverless') skipping validation when mode is undefined. An entry with no mode set passes validation but then hits the serverless submit path with a potentially empty URL. Fix: treat undefined as serverless in the validator too: if (!data.mode || data.mode === 'serverless').

Type cast fragility: (dc as { normal?: unknown }).normal

This cast appears in at least four places. Rivet.RunnerConfigResponse does not include a normal field. Centralise with a type guard to avoid repeated unsafe casts and make future API type updates easier to catch.

useEndpointHealthChecksValid empty-map contract

When no indicators are mounted (serverfull mode), statuses is {} and [].every(...) returns true, unblocking save correctly. But this relies on the indicator unmount cleanup setting status to 'idle' (which deletes the key). A short comment near setStatus explaining the deletion-on-idle contract would help future readers.

WhenMode silently defaults to "serverless"

A wrong name path silently renders the serverless subtree in serverfull mode. A dev-only warning when mode is undefined would help catch typos early.

Minor: blank line inside JSX props in serverless-endpoint-health.tsx near line 1292: extra blank line between the opening <WithTooltip tag and delayDuration={0}.

Missing test coverage: The pure helpers (extractErrorMessage, dcMode, dcSignatureWithoutMetadata, describeSwitches) are straightforward to unit-test and would be good starting points.

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Summary

Solid overall approach and meaningful UX improvements. Main things to address before merging:

1. Import ordering - move SERVERLESS_FIELDS after all imports.
2. validateRuntimeModeFields - treat undefined mode as serverless to match the submit handler.
3. Type cast centralisation - introduce a type guard for the repeated (dc as { normal?: unknown }).normal pattern.
4. Blank line in JSX - cosmetic cleanup in serverless-endpoint-health.tsx.

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[github-actions]

Preview packages published to npm

Install with:

npm install rivetkit@pr-4961

All packages published as 0.0.0-pr.4961.d447d31 with tag pr-4961.

Engine binary is shipped via @rivetkit/engine-cli on linux-x64-musl, linux-arm64-musl, darwin-x64, and darwin-arm64. Windows users should use the release installer or set RIVET_ENGINE_BINARY.

Docker images:

docker pull rivetdev/engine:slim-d447d31
docker pull rivetdev/engine:full-d447d31

Individual packages

npm install rivetkit@pr-4961
npm install @rivetkit/react@pr-4961
npm install @rivetkit/rivetkit-napi@pr-4961
npm install @rivetkit/workflow-engine@pr-4961