feat: double-back-to-exit on root tab screens by MatthieuTexier · Pull Request #457 · torlando-tech/columba

MatthieuTexier · 2026-02-13T07:56:16Z

Summary

Prevents accidental exits and annoying back-navigation between tabs. When on a root tab screen (Chats, Contacts, Map, Settings), pressing the system back button now shows a "Press back again to exit" toast instead of navigating to the previous tab. A second press within 2 seconds closes the app.

How it works

BackHandler is enabled only on root tab screens
First press → shows a Toast and sets a flag
LaunchedEffect auto-resets the flag after 2 seconds
Second press within the window → finish() on the activity

Files changed

app/src/main/java/com/lxmf/messenger/MainActivity.kt — added BackHandler + LaunchedEffect in ColumbaNavigation()

Testing

Build succeeds (compileNoSentryDebugKotlin)
detekt passes
ktlint passes
Manual test: back on root tab shows toast, double-back exits
Manual test: back on nested screens (messaging, settings sub-pages) still navigates normally

When on a root tab (Chats, Contacts, Map, Settings), pressing back shows a "Press back again to exit" toast instead of navigating between tabs. A second press within 2 seconds finishes the activity. Uses BackHandler with LaunchedEffect for lifecycle-aware timer reset.

greptile-apps · 2026-02-13T07:58:54Z

Greptile Summary

This PR adds a double-back-to-exit pattern for root tab screens (Chats, Contacts, Map, Settings) in ColumbaNavigation. When on a root screen, the first back press shows a "Press back again to exit" toast, and a second press within 2 seconds calls finish() to close the app. The implementation uses Compose BackHandler (enabled only on root routes), a remember state flag keyed on currentRoute to reset when switching tabs, and a LaunchedEffect to auto-reset after 2 seconds.

The core logic is clean and correctly handles edge cases (tab switching resets state, BackHandler is disabled on nested screens so normal navigation is unaffected)
The second commit (c316aa71) fixes the previously-reviewed issue where backPressedOnce persisted across tab switches by keying remember on currentRoute
Two minor style items: a fully-qualified kotlinx.coroutines.delay call and a non-alphabetical import ordering

Confidence Score: 4/5

This PR is safe to merge — it adds a well-scoped UX improvement with no functional regressions.
Score of 4 reflects a clean, focused change with correct logic, proper edge case handling (tab switching resets state), and no impact on nested screen navigation. Only minor style issues prevent a 5.
No files require special attention. The single changed file has been thoroughly reviewed.

Important Files Changed

Filename	Overview
app/src/main/java/com/lxmf/messenger/MainActivity.kt	Adds BackHandler with double-back-to-exit logic for root tab screens. Logic is sound; two minor style issues (FQ delay call, import ordering).

Sequence Diagram

sequenceDiagram
    participant User
    participant BackHandler
    participant State as backPressedOnce State
    participant Toast
    participant LaunchedEffect
    participant Activity as ComponentActivity

    User->>BackHandler: Press back (on root tab)
    BackHandler->>State: Check backPressedOnce
    alt First press (backPressedOnce = false)
        State-->>BackHandler: false
        BackHandler->>State: Set backPressedOnce = true
        BackHandler->>Toast: Show "Press back again to exit"
        BackHandler->>LaunchedEffect: Triggered (key changed)
        LaunchedEffect->>LaunchedEffect: delay(2000ms)
        LaunchedEffect->>State: Reset backPressedOnce = false
    else Second press within 2s (backPressedOnce = true)
        State-->>BackHandler: true
        BackHandler->>Activity: finish()
    end

    Note over User,Activity: Tab switch resets state via remember(currentRoute)

_{Last reviewed commit: c316aa7}

greptile-apps

_{1 file reviewed, 1 comment}

_{Edit Code Review Agent Settings | Greptile}

app/src/main/java/com/lxmf/messenger/MainActivity.kt

sentry · 2026-02-13T07:59:31Z

Codecov Report

❌ Patch coverage is 0% with 12 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...p/src/main/java/com/lxmf/messenger/MainActivity.kt	0.00%	12 Missing ⚠️

📢 Thoughts on this report? Let us know!

Key remember on currentRoute so the "press back again" flag resets when the user navigates to a different tab.

torlando-tech · 2026-02-17T02:42:51Z

@greptileai

greptile-apps

_{1 file reviewed, 2 comments}

_{Edit Code Review Agent Settings | Greptile}

greptile-apps · 2026-02-17T02:47:56Z

app/src/main/java/com/lxmf/messenger/MainActivity.kt

+    // Auto-reset the flag after 2 seconds
+    LaunchedEffect(backPressedOnce) {
+        if (backPressedOnce) {
+            kotlinx.coroutines.delay(2000)


Use an import for delay
kotlinx.coroutines.delay is used with a fully-qualified name here, while kotlinx.coroutines.launch is already imported at line 109. For consistency, add import kotlinx.coroutines.delay and use the short name.

Suggested change

kotlinx.coroutines.delay(2000)

delay(2000)

_{Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!}

Prompt To Fix With AI

This is a comment left during a code review. Path: app/src/main/java/com/lxmf/messenger/MainActivity.kt Line: 896:896 Comment: **Use an import for `delay`** `kotlinx.coroutines.delay` is used with a fully-qualified name here, while `kotlinx.coroutines.launch` is already imported at line 109. For consistency, add `import kotlinx.coroutines.delay` and use the short name. ```suggestion delay(2000) ``` <sub>Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!</sub> How can I resolve this? If you propose a fix, please make it concise.

greptile-apps · 2026-02-17T02:47:57Z

app/src/main/java/com/lxmf/messenger/MainActivity.kt

+import android.widget.Toast
 import android.provider.Settings


Import ordering is non-alphabetical
android.widget.Toast should come after android.provider.Settings to maintain alphabetical ordering within the android.* import group.

Suggested change

import android.widget.Toast

import android.provider.Settings

import android.provider.Settings

import android.widget.Toast

_{Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!}

Prompt To Fix With AI

This is a comment left during a code review. Path: app/src/main/java/com/lxmf/messenger/MainActivity.kt Line: 13:14 Comment: **Import ordering is non-alphabetical** `android.widget.Toast` should come after `android.provider.Settings` to maintain alphabetical ordering within the `android.*` import group. ```suggestion import android.provider.Settings import android.widget.Toast ``` <sub>Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!</sub> How can I resolve this? If you propose a fix, please make it concise.

greptile-apps bot reviewed Feb 13, 2026

View reviewed changes

app/src/main/java/com/lxmf/messenger/MainActivity.kt Outdated Show resolved Hide resolved

fix: reset back-press state when switching between root tabs

c316aa7

Key remember on currentRoute so the "press back again" flag resets when the user navigates to a different tab.

greptile-apps bot reviewed Feb 17, 2026

View reviewed changes

torlando-tech merged commit b705425 into torlando-tech:main Feb 17, 2026
10 of 11 checks passed

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feat: double-back-to-exit on root tab screens#457

feat: double-back-to-exit on root tab screens#457
torlando-tech merged 2 commits intotorlando-tech:mainfrom
MatthieuTexier:feature/back-press-confirm

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MatthieuTexier commented Feb 13, 2026

Summary

How it works

Files changed

Testing

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Greptile Summary

Confidence Score: 4/5

Important Files Changed

Sequence Diagram

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