fix(react-router-dev): Fix preset future flags merge

[juanpprieto]

Fixes #14368

Description

Preset-defined future flags were being completely ignored during configuration resolution. The bug prevented presets from enabling experimental features, which is critical functionality for third-party integrations like (Hydrogen)

Problem

The config resolution was incorrectly reading from reactRouterUserConfig.future instead of the merged userAndPresetConfigs.future at packages/react-router-dev/config/config.ts:589-599.

The merged configuration was already computed earlier (line 440-443):

let userAndPresetConfigs = mergeReactRouterConfig(
  ...presets,
  reactRouterUserConfig,
);

But the future flags resolution ignored this merged configuration entirely.

Solution

Changed all references from reactRouterUserConfig.future to userAndPresetConfigs.future to properly read from the merged configuration.

Testing

• Added integration test in integration/vite-presets-test.ts that verifies preset future flags are properly merged
• Test fails without the fix (all preset flags resolve to false)
• Test passes with the fix (preset flags are correctly applied)

pnpm test:integration --grep="presets"
# 16 passed (12.9s)

[changeset-bot]

🦋 Changeset detected

Latest commit: 8abdd99

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 11 packages

Name	Type
@react-router/dev	Patch
@react-router/fs-routes	Patch
@react-router/remix-routes-option-adapter	Patch
create-react-router	Patch
react-router	Patch
react-router-dom	Patch
@react-router/architect	Patch
@react-router/cloudflare	Patch
@react-router/express	Patch
@react-router/node	Patch
@react-router/serve	Patch

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[rbshop]

I can't explicitly approve, but (assuming it was indeed an oversight and not a deliberate decision) this looks good to me 👍

[github-actions]

🤖 Hello there,

We just published version 7.9.2-pre.2 which includes this pull request. If you'd like to take it for a test run please try it out and let us know what you think!

Thanks!

[github-actions]

🤖 Hello there,

We just published version 7.9.2 which includes this pull request. If you'd like to take it for a test run please try it out and let us know what you think!

Thanks!