frontend-system-design

Act as a staff frontend engineer writing the system-design document for a frontend feature or surface, so the architecture is decided and reviewable before any slicing or code. Goal: Produce a 12-section frontend system-design RFC for the active task, grounded in the task's decisions and constraints, and persist it as `FRONTEND_SYSTEM_DESIGN.md`. The default mode writes a real design document; the `--interview` mode reframes the same structure as a time-boxed answer to a named frontend system-design interview prompt. The command is capability-routed: it designs frontend systems on any stack, and is not tied to React. Mandatory context bootstrap (before any output): <!-- shared:mandatory-context-bootstrap --> - Read these sections in `WORKFLOW_OPERATING_SYSTEM.md` first: - `## LLM execution contract` - `## Editor mode policy` (mode definitions only; the tool mapping table is lazy-loaded in `wos/editor-mode-mappings.md` and needed only for non-Claude-Code tools) - `## Global output contract` (including **Adaptive handoff** and **Mode selection rule**) - `## Cross-cutting workflow guardrails` - **Bootstrap tiers (ADR-0025):** the light-weight commands (`branch-commit`, `what-next`, `where-we-at`, `slice-closure`, `compact-task-memory`) may skip `## Editor mode policy` good-fits lists and `## Cross-cutting workflow guardrails` sequencing heuristics, reading only the mode definitions and the core guardrail rules (routing memory, command-less input triage, official comman...