feat(live_ui): add AskSidebar widget Phoenix.Component (Wave 3.7-B Stage-4, DRAFT, Pascal-review REQUIRED)

[ty13r]

Summary

Wave 3.7-B canonical widget: AskSidebar — the Ask-mode sidebar shell that replaces :sidebar_shell when the operator is in Ask mode.

All 4 stages of the canonical widget pipeline are delivered (Stages 1–3 by parallel agents, Stage 4 by this PR):

• Stage 1 (IUR constructor): UnifiedIur.Widgets.Components.ask_sidebar/1 + :ask_sidebar added to @layer_callout_kinds — committed in 95b0233 (ThreadCard batch)
• Stage 2 (catalog entry): %{kind: :ask_sidebar, family: :layer_shell_and_callout, …} in unified_ui/widget_components.ex — committed in 95b0233 (ThreadCard batch)
• Stage 3 (renderer clause): Dedicated render(%{element: %Element{kind: :ask_sidebar}} = assigns) clause placed ABOVE generic @component_kinds fallback in live_ui/renderer.ex — committed in 931a440 (tree_view extension)
• Stage 4 (Phoenix.Component): LiveUi.Widgets.AskSidebar module with full render template — this PR

Widget contract

• Required attrs: :sidebar_id, :on_map_jump_event
• Optional attrs: :recent_items (list, cap 10), :saved_items (list), :active_item_id, :on_new_saved_event, :on_see_all_event, :empty_recent_label, :empty_saved_label, :blocker_count
• Root: <aside data-live-ui-widget="ask-sidebar" aria-label="Ask sidebar">
• Recent rail: <section aria-labelledby="ask-recent-h-{id}"> with relative timestamps + running-status indicator
• Saved rail: <section aria-labelledby="ask-saved-h-{id}"> with ★ glyph + cadence/last_run_at meta
• Map jump: <button aria-label="Switch to Map mode"> with optional blocker-count badge

Tests

• Stage 4 tests: 39 tests, 0 failures (packages/live_ui/test/live_ui/widgets/ask_sidebar_test.exs)
  • Component metadata (4), structural HTML (4), Recent rail (11), Saved rail (7), active item selection (4), Map jump affordance (5), see-all threshold (4)
• Stage 1 tests: committed in 95b0233 alongside the constructor
• Pre-existing failures (not caused by this widget): 7 unified_iur Phase-6 coverage gaps, 32 unified_ui parity synchronization failures

Open questions for Pascal review

These 8 questions are flagged in the @moduledoc and gate the transition from DRAFT to ready-to-merge:

1. Shell-swap vs section composition vs ariston-local? — Top design call. Current draft assumes option (a): new canonical widget swapping for :sidebar_shell.
2. Mode-switch mechanism: IUR re-render vs LiveView hot-swap?
3. "See all" overlay: internal vs event-to-host (current draft) vs deferred?
4. Saved rail filter at 20+ items: renderer threshold, host-supplied value, or v2?
5. Map jump placement: bottom of scroll vs sticky footer?
6. Width/position parity with :sidebar_shell: share CSS tokens or distinct?
7. Empty state for first-time user: combined onboarding vs per-rail labels (current draft).
8. Bottom identity bar (sb-bottom): part of widget contract or host-injected?

Pre-flight findings

• Stage 1 constructor: already committed 95b0233 ✓
• Stage 2 catalog entry: already committed 95b0233 ✓
• Stage 3 renderer clause (above @component_kinds fallback): already committed 931a440 ✓
• Stage 4 Phoenix.Component: this PR ✓
• Pre-existing compile warning in live_ui: LiveUi.Widgets.FileTreeBrowser.component referenced in renderer.ex but Stage-4 module missing — not caused by ask_sidebar, pre-existing from 95b0233

Test plan

• Pascal reviews 8 open questions and resolves shell-swap/composition design call
• Once design call resolved: update @moduledoc with decisions, remove open-questions section
• Smoke: mount AskSidebar in a dev IUR page; confirm Recent/Saved rail render and Map jump fires intent

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