bug: In version 0.86.0, after modifying code while in debug mode and re-running the command uv run flet debug android --device-id 29e6fb8f -vv, the app still executes the old unmodified code; the new code changes do not take effect.

[yst-one]

Duplicate Check

• I have searched the opened issues and there are no duplicates

Describe the bug

However, the APK generated by running uv run flet build apk installs and runs correctly on a mobile device.

Code sample

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To reproduce

1

Expected behavior

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Operating System

Windows

Operating system details

win11

Flet version

0.86.0

Regression

No, it isn't

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Additional details

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[FeodorFitsner]

Looking into that.

[FeodorFitsner]

Root cause found — this is an Android-specific caching bug in serious_python, not in the Flet debug workflow itself. Flet delivers the correct new code every time; serious_python was refusing to re-unpack it.

Mechanism

flet debug android re-packages your Python into app.zip, rebuilds the APK, and flutter run -d <device> reinstalls it — so your edits are inside the freshly installed APK's assets.

On launch, serious_python's Android plugin copies app.zip out of the APK to a writable dir, but only when a cache key changes. That key was versionName+versionCode (e.g. 1.0.0+1). Since flet debug never bumps the version between iterations, and flutter run does an update install that preserves app data (including the cache marker and the previously-unpacked app/), the key never changed → re-extraction was skipped → the app kept running the stale previously-unpacked code.

This is why:

• flet build apk works — fresh/version-bumped install, so the key differs and extraction runs.
• iOS/desktop are unaffected — they run the app from the read-only app bundle, which flutter run fully replaces on each reinstall.

Fix (serious_python)

The Android version key now also includes the APK's PackageManager.lastUpdateTime, which is bumped on every (re)install but stays stable across plain relaunches. So a flet debug reinstall now invalidates the cache and re-extracts the new code, while ordinary relaunches still hit the cache with no per-launch cost.

Will land in the next serious_python release; Flet will pick it up via a serious_python bump.

[yst-one]

The APK generated by flet build apk requires you to uninstall the old version on your phone first before reinstalling the new build for code changes to take effect. Make sure to double-check this step as well.