Context

Cost tiers should not be hardcoded constants — they need to be user-configurable entities that users can define, extend, and manage through the interface. This also needs to integrate with subscription-aware quota tracking (e.g. Claude Pro subscriptions have rate limits/quotas rather than pure per-token pricing).

In M1 (#55/#56), CostTier was changed from hardcoded dollar signs ($, $$) to string ID references (low, medium, high, premium) with SeniorityInfo.cost_tier accepting any str, not just the enum. This unblocks extensibility.

Acceptance Criteria

User-Configurable Cost Tiers

• CostTierDefinition model: id, display_name, description, price_range_min, price_range_max, color/icon (for UI)
• Built-in tiers (low, medium, high, premium) shipped as defaults, user can add/modify/remove
• Tiers referenced by string ID throughout the system (already done in M1)
• YAML config support for custom tier definitions

Subscription & Quota Awareness

• Support subscription-based providers (e.g. Claude Pro plan with rate limits, not just per-token cost)
• Quota tracking: requests/minute, tokens/day, monthly caps per provider/subscription
• Regular quota polling — query provider APIs for remaining budget/quota where available
• Graceful degradation when quota exhausted (fallback to cheaper provider, queue tasks, alert user)

Integration Points

• Connects to per-call cost tracking (Implement per-call cost tracking and usage logging #7)
• Feeds into budget enforcement engine (Implement budget enforcement engine with task-boundary auto-downgrade (DESIGN_SPEC §10.4) #44)
• CFO agent uses tier definitions for cost optimization recommendations (Implement CFO agent logic (spending monitoring, model downgrade suggestions) #46)

Design Notes

• Cost tiers are a bridge between the abstract seniority system and real-world provider economics
• Subscription tracking is fundamentally different from per-token tracking — needs its own model
• Consider caching provider quota responses to avoid excessive API calls
• Some providers (Ollama, local models) have zero cost but hardware resource limits — model this too

References

• DESIGN_SPEC.md 10.1-10.4 (budget hierarchy and cost controls)
• DESIGN_SPEC.md 9.2 (provider configuration with pricing)