[masenf]

Type of change

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

Description

Found in the reflex 0.11.0a1 pre-release testing (FINDING-029).

Reflex wrote .web/package.json as compact one-line JSON, and reflex.lock/package.json is a byte copy of that file. Whenever bun add changes the file, bun rewrites it 2-space indented. The persisted file therefore flipped between the two layouts and produced VCS diffs with no content change.

Every package.json writer now produces bun's layout:

• reflex_base.compiler.templates.package_json_template, which initialize_package_json and sync_root_package_json_to_web use
• frontend_skeleton.update_package_json_overrides

The layout is json.dumps(..., indent=2, ensure_ascii=False) + "\n", written as UTF-8 with newline="\n", so Windows writes LF like bun does. bun writes non-ASCII characters as raw UTF-8 rather than \uXXXX escapes. For that reason every package.json reader now uses encoding="utf-8": _read_package_json_object, js_runtimes._existing_web_package_sections and exec.get_package_json_and_hash. A file that is not valid UTF-8 is treated as unusable, the same as invalid JSON. The persisted copy is made with path_ops.cp, so it gets the same layout.

Checked against bun 1.4.4, the version reflex pins:

• bun add on a reflex-rendered file changes only the entries it adds. Its output equals json.dumps(json.loads(out), indent=2, ensure_ascii=False) + "\n".
• bun keeps whatever trailing newline the file already has. An indented file goes through bun add and bun remove byte-identical.
• bun keeps arrays expanded when they start expanded, which is how reflex writes them.

Changes To Core Features:

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

Every test below fails on main and passes with this change. Most of them run under a new windows_text_io fixture in tests/units/conftest.py. When no encoding or newline is given, the fixture makes text-mode file access decode as ASCII and translate LF to CRLF on writes.

• tests/units/utils/test_frontend_skeleton.py:
  • test_rendered_package_json_matches_bun_format and test_update_package_json_overrides_matches_bun_format: layout, UTF-8, and no \r in the file.
  • test_sync_root_package_json_repairs_unusable_file[\xff{}]: a non-UTF-8 file is repaired instead of raising.
• tests/units/utils/test_exec.py::test_get_package_json_and_hash_reads_utf8
• tests/units/utils/test_js_runtimes.py::test_existing_web_package_sections_reads_utf8

test_frontend_skeleton.py, test_exec.py, test_js_runtimes.py, test_prerequisites.py and tests/units/compiler pass, and ruff, ruff format, pyright and pre-commit are clean on the changed files.

🤖 Generated with Claude Code

https://claude.ai/code/session_01Dxjadq3qkhKnqZR2b9WBFi

[greptile-apps]

Confidence Score: 5/5

[Medium impact] The PR appears safe to merge; no new actionable issues were found.

Summary

This PR writes package.json with Bun-style indentation, raw UTF-8, and LF newlines to avoid whitespace-only changes.

• Reflex writes package.json files in the layout Bun keeps.

_{Reviews (3) · Last reviewed commit: "Treat a non-UTF-8 .web/package.json as u..." · Reviewed by Greptile}

[cubic-dev-ai]

All reported issues were addressed across 5 files

<sub>Reply with feedback, questions, or to request a fix.

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[codspeed]

Merging this PR will regress 1 benchmark

2 warnings

⚠️ 19 benchmarks are dominated by system calls

System calls cannot be simulated consistently and are left out of the measure. The reported value understates the real cost. Switch to the Walltime instrument to measure them.

Learn more about system calls

See affected benchmarks

⚠️ 2 benchmarks with a significant change ran on different hardware

Their base and head results were measured on machines with a different CPU, core count or memory, so the changes might not come from the code. Run base and head on the same runner type.

Learn more about Macro Runners

See affected benchmarks

⚡ 1 improved benchmark
❌ 1 regressed benchmark
✅ 149 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	test_state_access[read_cached_computed]	45.1 ms	47 ms	-4.13%
⚡	test_route_matching[10]	53.6 µs	50.5 µs	+5.97%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing fix/package-json-stable-format (5f0f47c) with main (f0088e0)}

[masenf]

CodSpeed is red here on test_process_event_burst_independent_tokens[1] (-4.7%), but this PR doesn't cause it. That benchmark shows the same 4–5% drop on every PR in this batch, and the previous run on this branch (740212e) reported no change. This PR only changes how package.json is written and read during reflex init / frontend setup; event processing never touches it. CodSpeed is not a required check; leaving it for acknowledgement on CodSpeed.

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