[harsh21234i]

Summary

When reflex run --json supervises a child process, a SIGINT sent to the supervisor PID can interrupt the supervisor without stopping the child. Forward SIGINT to the running child on POSIX so process supervisors configured with stopsignal=INT can stop Reflex cleanly.

Closes #7509.

Testing

• uv run pytest tests/units/reflex_base/utils/test_log.py -q — 80 passed, 2 skipped on Windows.
• Linux PID-targeted SIGINT regression test — 1 passed.
• Applicable pre-commit hooks — passed.

[cubic-dev-ai]

All reported issues were addressed across 3 files

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

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[greptile-apps]

Confidence Score: 5/5

[Medium impact] The reviewed changes appear safe to merge, with no new blocking findings.

Summary

This PR forwards SIGINT to the supervised child on POSIX when the JSON supervisor catches a keyboard interrupt.

• JSON-mode runs pass a supervisor's SIGINT to the app child on POSIX.

_{Reviews (9) · Last reviewed commit: "Merge branch 'main' into fix/7509-json-r..." · Reviewed by Greptile}

[codspeed]

Merging this PR will improve performance by 4.01%

2 warnings

⚠️ 17 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

⚠️ Base and head ran on different runner types

Some benchmarks with significant performance changes were compared across different runner types, so the changes might not come from the code. Run base and head on the same runner type, or use CodSpeed Macro Runners for more stable results.

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⚡ 1 improved benchmark
✅ 147 untouched benchmarks

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	test_proxy_list_mutation	9.9 ms	9.5 ms	+4.01%

Tip

Curious why performance improved? Comment @codspeedbot explain why performance improved on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing harsh21234i:fix/7509-json-run-sigint (febfe77) with main (74bcd8b)}

[cubic-dev-ai]

All reported issues were addressed across 4 files (changes from recent commits).

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

View guided diff | Re-trigger cubic</sub>

[masenf]

thanks. this is important. i just want to make sure we're not introducing a hard to debug future problem

[greptile-apps]

Comments Outside Diff

These findings could not be posted inline.

•  Startup interrupts leave apps running packages/reflex-base/src/reflex_base/utils/log.py:518 ▶

  supervise_output now catches SIGINT only while waiting for the child. If a supervisor sends a PID-only interrupt after Popen starts the child but before the wait loop begins, KeyboardInterrupt escapes without signaling or stopping the child. The supervisor exits while the app keeps running. Keep interrupt forwarding active from child creation through the wait loop.