fix: address technical debt - memory leaks, stub implementations, refactor AppBar and MultiPanelLayout

[ElectricCookie]

Summary

• Fix memory leaks in LdMonkeyShellState and LdMonkeyShell (StreamControllers now properly disposed)
• Fix LdSelectableList FocusNode and GlobalKey leaks in dispose()
• Remove LdScaffoldSlotExtension stub and fix broken level/effectiveHeight methods
• Fix maybePopContextMenu to return actual pop result instead of always true
• Remove dead code from repository.create()
• Extract scroll behavior and decoration logic from LdAppBar (~231 lines)
• Extract drag gesture handler from LdMultiPanelLayout
• Extract LdSelectableListSelectionController into separate file (~269 lines)

Test plan

• dart analyze passes with no issues
• All tests pass
• Golden tests pass (if applicable)

Fixes #75

[ElectricCookie]

Code Review Findings

Medium: Not Integrated

File: multi_panel_layout.dart

The extracted handler class in exists but is never imported/used by . Drag state still duplicates the extracted logic.

Documentation Gaps for Extracted Code

• • 121 lines, no class docs
• • 362 lines, no class docs
• • 193 lines, minimal docs

Type Invariant Issue

File:
When , silently truncates to first item instead of throwing.

Test Coverage Gaps

• • no dedicated tests
• • behavior change untested
• Dispose behavior - no regression tests for memory leak fixes

[ElectricCookie]

Code Review - Overall Assessment

PR #81 addresses technical debt cleanup for issue #75 with good progress on memory leak fixes and refactoring. However, there are some items to address before merge.

Findings Summary

1. Medium: extracted but not integrated into - code duplication remains

2. Nitpick: Documentation gaps for 3 substantial extractions totaling ~676 lines

3. Nitpick: invariant violation when

4. Test gaps: Memory leak fixes and behavior changes lack regression tests

What's Done Well

• Memory leak fixes properly implemented (dispose patterns correct)
• Stub implementations removed
• Refactoring is clean with good separation
• now returns actual pop result

[ElectricCookie]

Code Review Findings

1. Orphaned removeListener (monkey_shell.dart:310)
_state.removeListener(_onStateChange) is called but addListener was never called. This is dead code.

2. Inconsistent exception handling (repository.dart:338-358)
create() returns T? but rethrows on error instead of returning null.

3. Silent Failure: Missing await (repository.dart:347)
applyOptimisticFilterAndSorting() called without await - fire-and-forget pattern.

4. Silent Failure: Secondary exception swallowed (repository.dart:382-384)
refreshList() failure is silently absorbed before rethrow.

5. Test Coverage Gap
LdSelectableListSelectionController, LdMultiPanelDragGestureHandler, LdAppBarDecorationBuilder lack unit tests for edge cases.

[ElectricCookie]

Fixed issues 1, 2, and 3:

1. monkey_shell.dart:310 - Removed orphaned _state.removeListener(_onStateChange) from dispose() - addListener was never called

2. repository.dart:356 - Changed rethrow to return null in create() catch block - now consistent with return type Future<T?>

3. repository.dart:347 - Added missing await to applyOptimisticFilterAndSorting() call

[ElectricCookie]

Fixed 3 review findings in commit 28cbdcb:

1. monkey_shell.dart:310 - Removed orphaned _state.removeListener(_onStateChange) from dispose() (addListener was never called)
2. repository.dart:347 - Added missing await to applyOptimisticFilterAndSorting() call
3. repository.dart:356 - Changed rethrow to return null for consistent Future<T?> return type

Ready for re-review.