Epic expand/collapse broken in Active/Ready view modes

[dreamiurg]

Bug Description

When using the V key to switch to Active or Ready view mode, epic expand/collapse stops working. The triangle indicator (▼/▶) toggles visually when clicking or pressing Space/arrow keys, but the tree doesn't actually expand or collapse - children remain visible regardless of the indicator state.

Steps to Reproduce

1. Open Abacus in a repository with epics that have children
2. Press V to switch to Active view (or press again for Ready view)
3. Try to collapse an expanded epic using Space, Right arrow, or clicking the triangle
4. Observe: Triangle changes from ▼ to ▶, but children remain visible

Expected Behavior

Children should hide when the epic is collapsed, matching the triangle indicator state.

Actual Behavior

Triangle toggles visually but children remain visible. The expand/collapse has no effect.

Environment

• Abacus version: 0.8.0
• OS: macOS (Darwin 24.6.0)

Root Cause Analysis

The bug is in internal/ui/state_expansion.go. The functions expandNodeForView() and collapseNodeForView() check m.filterText == "" to decide whether to track filter override state (filterForcedExpanded/filterCollapsed), but they ignore view mode filtering (m.viewMode != ViewModeAll).

When in Active/Ready view mode:

• filterText is empty, so the early return triggers
• Filter override state is never set
• shouldExpandFilteredNode() uses default behavior instead of user's explicit toggle

Fix

I have a fix ready in my fork that:

1. Adds isFilterActive() helper checking both text filter AND view mode
2. Uses this helper consistently in expandNodeForView(), collapseNodeForView(), isNodeExpandedInView(), and recalcVisibleRows()
3. Includes a regression test TestViewModeExpandCollapse

Will submit a PR shortly.