feat(billing): replace coupon with intro pricing and enable promo codes

[jeanduplessis]

Summary

• Replace the Stripe coupon-based first-month discount for Standard plan with an introductory price approach (STRIPE_KILOCLAW_STANDARD_INTRO_PRICE_ID), enabling allow_promotion_codes: true on all KiloClaw checkout sessions (both Standard and Commit plans). This unblocks Rewardful affiliate promo code entry, which was previously blocked by Stripe's mutual exclusivity between discounts and allow_promotion_codes.
• New ensureAutoIntroSchedule idempotent helper creates a 2-phase Stripe subscription schedule (intro → regular standard price) with end_behavior: 'release', called from subscription.created webhook, reactivation, and cancel-plan-switch flows. Auto schedules are tagged with metadata.origin: 'auto-intro' to distinguish them from user-initiated plan switches.
• All billing flows (cancel, reactivate, switchPlan, cancelPlanSwitch) updated to handle auto schedules transparently — live-fetch reconciliation detects "hidden schedules" (Stripe has schedule but DB pointer is null) and handles them correctly. Auto schedules are invisible in the UI; users can still switch plans or cancel without interference.
• New billing lifecycle cron sweep repairs stranded intro-price subscriptions that are missing their auto schedule (e.g., due to partial failure during schedule creation).

Verification

• pnpm typecheck — passed (all packages)
• pnpm jest src/routers/kiloclaw-billing-router.test.ts — 42 tests passed
• pnpm run format:check — passed
• pnpm run lint — passed (0 warnings, 0 errors)
• Pre-push hooks (format, lint, typecheck) — all passed
• Spec verification: all 12 relevant spec rules verified as PASS against implementation

Visual Changes

N/A

Reviewer Notes

• Pre-deploy manual step: Create a new Stripe Price for Standard at the intro amount (recurring monthly), set its ID in STRIPE_KILOCLAW_STANDARD_INTRO_PRICE_ID. After deploy, STRIPE_KILOCLAW_STANDARD_FIRST_MONTH_COUPON_ID can be removed from environment.
• Key architectural pattern: ensureAutoIntroSchedule uses a live Stripe fetch as single source of truth — it never trusts stale webhook payloads or DB state for schedule decisions. Race guards handle concurrent schedule creation. Partial failures are tolerated: the cron sweep (sweep 5) repairs stranded subscriptions on subsequent runs.
• Hidden-schedule reconciliation in cancel/switchPlan flows ensures that even if the DB loses its schedule pointer (e.g., Stripe schedule created but DB persist failed), the schedule is still detected and handled correctly via live fetch.
• as casts minimized: Stripe schedule/price references use typeof checks with .id fallback instead of as string casts, per coding style rules.
• Assumption: Rewardful promo codes are configured as one-time (first-invoice-only) discounts. If recurring promo discounts are needed, schedule phase definitions must forward discounts from the current phase.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (2 files)

• src/routers/kiloclaw-billing-router.test.ts
• src/routers/kiloclaw-router.ts

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_{Reviewed by gpt-5.4-20260305 · 275,297 tokens}