Opportunity and calendar cards now isolate item rendering behind memoized components. This preserves the current action grouping and copy while preventing selection or parent dashboard updates from re-rendering every dense card body.
Constraint: Do not change ranking, grouping, or product wording in this performance pass.
Rejected: Introduce virtual list dependency | the current list size can benefit from memo boundaries first without new dependencies.
Confidence: high
Scope-risk: narrow
Reversibility: clean
Tested: TypeScript diagnostics for CalendarView and OpportunityOverview
Tested: npm run build
Not-tested: Browser profiler capture with a large production city set.
Users need to know whether a city can be acted on before reading the full explanation. City cards now expose METAR or official-observation freshness, model update timing, market quote freshness, and AI state in a dedicated trust block, while the calendar view groups rows into action-oriented timing buckets with a single reason per city.
Constraint: Keep the existing card and calendar data contracts; derive freshness and action reasons from fields already present in the frontend payload.
Rejected: Add another long explanatory paragraph | it would repeat the same trust problem instead of making the first glance clearer.
Confidence: high
Scope-risk: moderate
Reversibility: clean
Tested: npm run build
Not-tested: Live browser visual QA with stale METAR and delayed quote examples.
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