fix(hmr): stop unloaded-route edits from wedging browser HMR

[FarhanAliRaza]

React Router queues manifest updates for lazy routes even when their modules aren't loaded in the browser. Its HMR runtime throws on those entries before clearing the queue, blocking every later hot update until a full page reload. Add a Vite plugin that patches the runtime to skip unloaded routes instead of throwing.

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Type of change

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• Bug fix (non-breaking change which fixes an issue)

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[codspeed-hq]

Merging this PR will not alter performance

✅ 26 untouched benchmarks
⏩ 8 skipped benchmarks¹

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_{Comparing FarhanAliRaza:wedging-issue (9d27690) with main (65a2889)}

Footnotes

1. 8 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[greptile-apps]

Greptile Summary

This PR fixes a browser HMR wedge in React Router by adding a Vite plugin that patches the react-router HMR runtime at serve time, replacing a throw on unloaded routes with a continue so the update queue is not poisoned by routes that haven't been loaded in the browser yet.

• templates.py: Adds patchReactRouterHmrRuntime() as an enforce: "post" Vite plugin (serve-only) that regex-patches the virtual react-router/hmr-runtime module. Graceful degradation via this.warn() is included for when the upstream code changes.
• test_hmr.py: Adds a new Playwright integration test that verifies: editing an unloaded route sends a manifest update, and a subsequent edit to the loaded index route still triggers a DOM hot-update (i.e., the queue is not wedged).

Confidence Score: 5/5

Safe to merge — the plugin only runs in dev/serve mode, the regex patch is narrow and well-contained, and the graceful-degradation warn path protects against upstream react-router changes.

The Vite plugin replaces a single throw with continue inside the react-router HMR loop, scoped entirely to apply: serve. The regex is carefully anchored to the exact error pattern, and the this.warn() fallback ensures nothing breaks silently if react-router changes its internal structure. The new integration test exercises the exact failure scenario end-to-end.

No files require special attention.

Important Files Changed

Filename	Overview
packages/reflex-base/src/reflex_base/compiler/templates.py	Adds a post-enforce Vite plugin that patches the react-router HMR runtime regex at serve time; includes graceful warn fallback when the upstream pattern changes.
tests/integration/tests_playwright/test_hmr.py	New integration test verifying unloaded-route edits no longer block subsequent loaded-route HMR updates; uses programmatically derived route IDs and a correct scan_pos cursor.
packages/reflex-base/news/6774.bugfix.md	Changelog entry for the bugfix; one-line description, no issues.

_{Reviews (2): Last reviewed commit: "test(hmr): derive generated route paths ..." | Re-trigger Greptile}