fix(rename): read and write source files as UTF-8

[anxkhn]

All Submissions:

• Have you followed the guidelines stated in CONTRIBUTING.md file?
• Have you checked to ensure there aren't any other open Pull Requests for the desired changed?

Type of change

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

What and why

reflex rename <new_name> walks the user's app and rewrites imports and the app
name in every .py and .md file. The read/modify/write in
rename_imports_and_app_name (reflex/utils/rename.py) used
Path.read_text() and Path.write_text() with no encoding= argument, so both
default to the platform's locale encoding. On a Western Windows locale that is
cp1252, not UTF-8.

The consequences on non-UTF-8 locales:

• Silent corruption (Western Windows, cp1252): a UTF-8-authored file that
  contains non-ASCII bytes (curly quotes in docstrings, accented identifiers or
  string literals, emoji) is decoded as cp1252, rewritten, and written back as
  cp1252, mangling the user's own source.
• Hard failure (CJK codepages): read_text() raises UnicodeDecodeError,
  aborting the rename partway through the tree and leaving some files already
  rewritten and others not, i.e. an inconsistent app.

On a POSIX UTF-8 locale it round-trips, so this is effectively Windows-specific.

The fix passes encoding="utf-8" on both calls. This mirrors the repo's own
reflex/utils/path_ops.py find_replace, which already reads and writes the same
read/replace/write pattern with encoding="utf-8"; rename.py was the outlier.

Changes

• reflex/utils/rename.py: add encoding="utf-8" to the read_text() and
  write_text() calls in rename_imports_and_app_name (+2 / -2).
• tests/units/test_prerequisites.py: add regression test
  test_rename_imports_and_app_name_preserves_utf8, colocated with the existing
  rename tests. It simulates a cp1252 default (monkeypatching Path.read_text /
  write_text so a missing encoding falls back to cp1252, while an explicit
  encoding= still passes through), writes a UTF-8 file with realistic non-ASCII
  content, runs the rename, and asserts the bytes are preserved exactly and the
  rename still happened. The test fails before the fix (UnicodeDecodeError) and
  passes after.
• news/<pr>.bugfix.md: towncrier changelog fragment.

Changes To Core Features:

• Have you added an explanation of what your changes do and why you'd like us to include them? (above)
• Have you written new tests for your core changes, as applicable?
• Have you successfully ran tests with your changes locally?

Locally (all green):

• uv run pytest tests/units/test_prerequisites.py -k rename -> 6 passed
• uv run pytest tests/units/test_prerequisites.py tests/units/utils -> 677 passed, 4 skipped
• uv run ruff check . (changed files) -> All checks passed
• uv run ruff format --check . (changed files) -> already formatted
• uv run pyright reflex/utils/rename.py tests/units/test_prerequisites.py -> 0 errors
• uv run towncrier check --compare-with origin/main -> fragment found

[greptile-apps]

Greptile Summary

This PR makes reflex rename preserve source-file encodings across platforms. The main changes are:

• Detect Python source encodings with tokenize.detect_encoding.
• Read and write each Python file with its detected encoding.
• Use UTF-8 explicitly for supported non-Python text files.
• Add byte-level tests for UTF-8 and cp1252 source files.
• Add a bug-fix changelog entry.

Confidence Score: 5/5

This looks safe to merge.

• The declared-encoding failure is addressed with Python's standard source-encoding detection.
• Reads and writes now use the same detected encoding.
• Tests cover both UTF-8 files on non-UTF-8 locales and cp1252 encoding declarations.
• No blocking issues were found in the updated code.

Important Files Changed

Filename	Overview
reflex/utils/rename.py	Detects declared Python source encodings and reuses them for reading and writing during rename.
tests/units/test_prerequisites.py	Adds byte-level tests for UTF-8 under a cp1252 locale and Python source declared as cp1252.
news/6714.bugfix.md	Documents the cross-platform source-encoding fix.

_{Reviews (4): Last reviewed commit: "test(rename): handle platform newlines" | Re-trigger Greptile}

[chatgpt-codex-connector]

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[codspeed-hq]

Merging this PR will not alter performance

✅ 26 untouched benchmarks
⏩ 8 skipped benchmarks¹

---

_{Comparing anxkhn:patch-13 (4f7d658) with main (1358e00)}

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. ↩

[anxkhn]

fixed the windows ci failures in 4f7d658. the encoding assertions remain byte-exact while accounting for the platform newline emitted by the existing text-write behavior. focused tests, ruff, and pyright pass locally. @reflex-dev please take another look when ci completes.