ADFA-2730 | Fix crash during file tree loading

[jatezzz]

Description

Fixed a DiagnosticCoroutineContextException (caused by IllegalStateException: Fragment not attached to a context) that occurred when navigating back from the file tree selection screen while files were still loading.

The crash happened because requireContext() was being invoked inside a background coroutine (Dispatchers.IO) after the Fragment had already been detached.

I fixed this by:

1. Capturing the Context safely in the main thread before the background operation starts.
2. Passing this context as a parameter to the recursive buildTreeNodes function.
3. Adding currentCoroutineContext().ensureActive() inside the loop. This ensures the background operation stops immediately if the user navigates away, preventing the code from attempting to use resources after detachment.

Details

Stacktrace addressed:

java.lang.IllegalStateException: Fragment FileTreeSelectionFragment not attached to a context.
    at androidx.fragment.app.Fragment.requireContext
    at com.itsaky.androidide.fragments.sidebar.FileTreeSelectionFragment.buildTreeNodes

Before changes

Screen.Recording.2026-02-03.at.12.05.10.PM.mov

After changes

Screen.Recording.2026-02-03.at.5.12.52.PM.mov

Ticket

ADFA-2730

Observation

The addition of ensureActive() is critical to ensure cooperative cancellation, preventing the background thread from continuing to process files unnecessarily after the screen is closed.

[coderabbitai]

📝 Walkthrough

Release Notes: Fix crash during file tree loading (PR #920)

• Fixed crash caused by DiagnosticCoroutineContextException ("Fragment not attached to a context") when navigating back from the file-tree selection screen while files were still loading.
• Captures Context on the main thread before starting background processing and passes it into the tree-building routine.
• Converted tree construction to a suspending function (buildTreeNodes) that runs on a background dispatcher and accepts an explicit Context parameter.
• Added cooperative cancellation by calling currentCoroutineContext().ensureActive() inside the file-processing loop so traversal stops immediately when the coroutine is cancelled.
• Guarded UI updates with isAdded (fragment-attached) checks before calling setupTreeView and other fragment-bound operations.
• Adjusted selected-files handling and path computations to use explicit parameters and target File instances; switched traversal to use target.walkTopDown for clarity.

⚠️ Risks & Best-practice concerns

• File I/O lacks explicit try/catch: permission issues or IO errors (e.g., listFiles() returning null) may still cause failures or incomplete trees.
• Recursion depth is unbounded: extremely deep directory hierarchies could cause stack-overflow.
• No limits on processed files/memory: very large repositories (thousands of files) may still consume excessive memory or impact UI rendering performance.
• Silent handling of null listFiles(): skipped directories are not logged or surfaced to the user.
• Passing Context objects across threads increases risk if the Context is an Activity; ensure the Context used is appropriate (application Context when long-lived references are needed).

Testing recommendations

• Rapidly navigate away while file tree is loading to verify cooperative cancellation.
• Test with very large (10k+) and deeply nested (>500 levels) directory structures.
• Test with directories having restricted permissions and verify failures are handled gracefully.

Walkthrough

Refactors fragment tree construction to a suspending, context-aware builder that checks coroutine cancellation, passes an explicit Android Context to node/view-holder creation, and guards UI setup behind fragment attachment state.

Changes

Cohort / File(s)

Summary

Tree Building Refactor app/src/main/java/com/itsaky/androidide/fragments/sidebar/FileTreeSelectionFragment.kt

Replaced synchronous traversal with a private suspend fun buildTreeNodes(context: Context, ...); added currentCoroutineContext().ensureActive() checks during iteration; use passed Context for MultiSelectFileTreeViewHolder/node creation; guard setupTreeView with isAdded; updated lambda parameter names and path handling; added imports android.content.Context, kotlinx.coroutines.currentCoroutineContext, kotlinx.coroutines.ensureActive.

Sequence Diagram(s)

(omitted)

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Suggested reviewers

• itsaky-adfa
• jomen-adfa
• dara-abijo-adfa

Poem

🐇 I hopped through folders, light and spry,

Suspending steps beneath the sky,
Context cradled in my tiny paw,
Coroutines humming as I saw,
Nodes aligned—ready to fly ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'ADFA-2730 | Fix crash during file tree loading' directly and concisely describes the main change: fixing a crash in file tree loading with the ticket reference.
Description check	✅ Passed	The description is comprehensive and directly related to the changeset, explaining the crash, root cause, and three specific fixes implemented in the code.

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✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch fix/ADFA-2730-file-tree-crash

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