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ADR-0016: Approve AI Tooling Costs for Project Arc – Phase 1

  • Status: ✅ Accepted
  • Date: 2026-06-04
  • Owners: @ozcan, @osmanc

Context

Project Arc requires two external AI subscriptions to operate: a Claude Team seat for the agent core, and a CodeRabbit Pro seat for automated PR review on Arc's pull requests.

Decision

Approve the following subscriptions:

  • Claude Team - 1 seat, $125/month
  • CodeRabbit Pro - 1 seat scoped to Arc's GitHub user, $30/month

Combined monthly cost: $155/month. A second Claude seat ($125/month) may be added later if usage warrants it, bringing the ceiling to $280/month.

Options Considered

  • Claude Enterprise - rejected; significantly higher cost with no capability gain at Arc's current scale (single assistant, limited user count).
  • CodeRabbit org-wide - rejected; org-wide pricing applies a per-seat cost to every GitHub user in the organization (~30 users x $30 = ~$900/month). Arc's single-seat approach limits automated review to PRs opened by Arc only.
  • Free tiers only - rejected; Anthropic's free tier does not support the session continuation and prompt caching features Arc depends on for multi-turn Slack threads.

Consequences

  • $155/month recurring cost starting at launch.
  • CodeRabbit scope must remain limited to Arc's GitHub user - any org-wide expansion is a separate decision.
  • Gemini (critic gate) and Context7 (library docs) are on free tiers; a follow-up ADR will be opened if paid tiers become necessary.
  • Related: TDD-0005 (Project Arc Technical Design Document)