feat(ui): make What's Next feed scrollable beyond 5 items

[dimakis]

Summary

• Remove the hard MAX_ITEMS=5 cap from useAttentionFeed hook — all attention items are now returned
• Component shows first 5 items by default with a "Show all N" / "Show less" toggle button
• Header badge now shows the true tier-1 count (was previously capped at 5)

Test plan

• Updated useAttentionFeed test: verifies all 10 items returned (was asserting 5-cap)
• Verify on mobile: "What's Next" shows 5 items, tap "Show all" to expand, "Show less" to collapse
• Verify badge count shows true total when >5 sessions awaiting reply

🤖 Generated with Claude Code

[dimakis]

Centaur Review

Found 2 issue(s).

frontend/src/components/AttentionFeed.tsx

Clean, well-scoped change that correctly moves the display cap from hook to component. No bugs or regressions — just a minor stale-state edge case and missing component tests for the new toggle.

• 🔵 missing_tests: No component-level tests for the new show-more/show-less toggle behavior. The project has component tests for other components (ToolPill, ToolGroup, CodeBlock, etc.). Consider adding tests that verify: (1) only 5 items render by default, (2) clicking 'Show all' renders all items, (3) the button doesn't appear when there are <= 5 items, (4) the button label shows the correct total count. [fixable]
• 🔵 bugs (L54): If the user clicks 'Show all' and items subsequently shrink below DEFAULT_VISIBLE_COUNT (e.g., a todo is completed), showAll stays true but hasMore becomes false, hiding the button. The user can never click 'Show less' — they're stuck with showAll=true, though it's functionally harmless since slice(0, 5) on fewer items returns all of them anyway. Not a real bug, but the state is stale. [fixable]

[dimakis]

🔵 bugs: If the user clicks 'Show all' and items subsequently shrink below DEFAULT_VISIBLE_COUNT (e.g., a todo is completed), showAll stays true but hasMore becomes false, hiding the button. The user can never click 'Show less' — they're stuck with showAll=true, though it's functionally harmless since slice(0, 5) on fewer items returns all of them anyway. Not a real bug, but the state is stale. [fixable]