HAC-95: Add paid retention and MRR health analytics

[ross0x01]

Summary\n\n- classify subscription churn as voluntary, involuntary, dispute, or unknown\n- add subscription, attributed, retained, at-risk, and lost MRR to Stripe-backed analytics\n- use the immutable paid-invoice Price and quantity so delayed webhooks cannot misstate MRR\n- retain the PostHog paid-retention dashboard for at-risk users, upgrade conversion, and voluntary cancellations\n- remove all new paid model-quality experiment code; application model routing matches current main\n\n## PostHog\n\n- Deleted the HAC-95 Standard and Pro draft experiments from Preview and Production\n- Retained the paid-retention dashboard\n- HAC-46 pricing experiment remains paused in Preview and Production\n\nThis PR does not introduce or launch a model-routing experiment.\n\n## Validation\n\n- Typecheck passes\n- Lint passes with no errors; existing unrelated warnings only\n- 441 test suites / 4,574 tests pass\n- Current main merged cleanly\n- PR diff is limited to four billing and retention analytics files\n\n## Manual verification after deploy\n\n1. Trigger a paid renewal in the Stripe test environment.\n2. Confirm invoice_paid contains retained and attributed MRR based on the paid invoice Price and quantity.\n3. Cancel one test subscription voluntarily and simulate one payment-failure cancellation.\n4. Confirm cancellation events classify churn correctly and the retention dashboard updates.\n\nTracking: HAC-95

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Project	Deployment	Actions	Updated
hackerai	Ready	Preview	Sep 3, 2026 3:24pm UTC

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📒 Files selected for processing (2)

• app/api/subscription/webhook/__tests__/route.test.ts
• app/api/subscription/webhook/route.ts

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• app/api/subscription/webhook/tests/route.test.ts
• app/api/subscription/webhook/route.ts

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📝 Walkthrough

Walkthrough

The change adds invoice-quantity-based MRR attribution and churn classification to subscription analytics. It also introduces paid model quality experiments, replaces the DeepSeek integration, and records experiment exposure and completion telemetry.

Changes

Subscription analytics

Layer / File(s)	Summary
Churn health classification lib/analytics/paid-funnel.ts, lib/__tests__/paid-funnel.test.ts	Adds classification for payment failures, cancellation requests, disputes, and unknown reasons.
Webhook MRR and churn events app/api/subscription/webhook/route.ts, app/api/subscription/webhook/__tests__/route.test.ts	Uses paid invoice quantity, with subscription quantity as fallback, for revenue and MRR analytics. Cancellation events include churn classification and MRR fields. Tests cover historical-price payments and cancellation cases.

Paid model quality experimentation

Layer / File(s)	Summary
Experiment routes and assignments lib/experiments/paid-model-quality.ts, lib/experiments/__tests__/paid-model-quality.test.ts	Adds route eligibility, PostHog flag evaluation, variant-to-model mapping, fail-closed handling, and assignment validation.
Assignment and event analytics lib/experiments/paid-model-quality.ts, lib/experiments/__tests__/paid-model-quality.test.ts	Adds experiment context, exposure events, and completed-run events with model, outcome, timing, fallback, recovery, and step-limit fields.
Chat and agent integration lib/api/chat-handler.ts, lib/api/chat-logger.ts, lib/api/__tests__/chat-logger.test.ts, trigger/agent-long.ts	Replaces DeepSeek experiment calls with paid model quality APIs and records exposure and completion analytics.

Estimated code review effort: 4 (Complex) | ~45 minutes

Merge Risk: ⚪ Minimal · up to 12e1f

Paid MRR analytics now use the invoice quantity, improving attribution for multi-quantity subscriptions. The associated webhook tests and reported validation are complete, with no current merge-blocking risk identified.

Sequence Diagram(s)

sequenceDiagram
  participant ChatHandler
  participant PaidModelQuality
  participant PostHog
  participant ChatLogger
  ChatHandler->>PaidModelQuality: Evaluate paid model quality experiment
  PaidModelQuality->>PostHog: Evaluate route feature flag
  PostHog-->>PaidModelQuality: Return experiment assignment
  ChatHandler->>PaidModelQuality: Capture experiment exposure
  PaidModelQuality->>PostHog: Send exposure event
  ChatLogger->>PaidModelQuality: Capture completed run
  PaidModelQuality->>PostHog: Send run event

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🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 16.67% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 18 functions across 10 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title is concise, specific, and directly describes the added retention and MRR health analytics. These changes are present in the pull request objectives and implementation.

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Actionable comments posted: 1

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Inline comments:
In `@app/api/subscription/webhook/route.ts`:
- Line 762: Update the invoice-paid MRR calculation near subscriptionMrrDollars
to use the quantity from the matching paid-invoice line rather than
subscription.items data, while retaining the existing fallback behavior if
appropriate. Add a regression test covering a paid invoice quantity that differs
from the current subscription quantity and assert MRR uses the invoice quantity.

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📥 Commits

Reviewing files that changed from the base of the PR and between b442ee5 and 9c4bc14.

📒 Files selected for processing (12)

• app/api/subscription/webhook/__tests__/route.test.ts
• app/api/subscription/webhook/route.ts
• lib/__tests__/paid-funnel.test.ts
• lib/analytics/paid-funnel.ts
• lib/api/__tests__/chat-logger.test.ts
• lib/api/chat-handler.ts
• lib/api/chat-logger.ts
• lib/experiments/__tests__/deepseek-v4-pro-0813.test.ts
• lib/experiments/__tests__/paid-model-quality.test.ts
• lib/experiments/deepseek-v4-pro-0813.ts
• lib/experiments/paid-model-quality.ts
• trigger/agent-long.ts

💤 Files with no reviewable changes (2)

• lib/experiments/tests/deepseek-v4-pro-0813.test.ts
• lib/experiments/deepseek-v4-pro-0813.ts

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