Closes the obvious gaps remaining in the family:
- add_filter_group_v0 — sidebar facet (heading + checkbox-style options
with optional counts). Distinct from nav_chip_row (horizontal scrolling
chips), tag (single applied chip), segmented_control (mutex tabs).
- add_invite_row_v0 — pending invite row (avatar + email/role + status
pill + trailing action). Distinct from member_row (a JOINED member,
no status pill or action) and list_row (no avatar / status / action).
- add_activity_log_v0 — single-line audit feed entry (optional tinted
icon dot + actor in bold + action + right-aligned timestamp). Uses
StyledTextSegment[] content for the bold/regular split. Distinct from
timeline (multi-event vertical with connectors) and notification_row
(title + body, no actor focus).
- add_event_card_v0 — single calendar event tile (date column with
month band + day number, then title + time + location). Distinct from
calendar_grid (the full month grid) and card_row (no date column).
- add_step_card_v0 — onboarding step card (numbered circle / check +
title + description). Distinct from stepper (horizontal progress nav
with connectors) and faq_item (collapsible Q&A header).
9 touchpoints per tool: pen-core builder + index + barrel + types,
pen-mcp handler + dispatcher + ext-4 schema, apps/web shim +
SERVER_BUILDERS, parity test (+5 cases), elements.md decision tree
items 86-89 + 6 PREFER mappings with cross-links to existing tools,
elements-cookbook.md arg-shape examples (8 entries across 5 tools).
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