P6 E Execution Checklist

# P6-E Execution Checklist
 
Execution checklist for `P6-E: Tenant Carrier Config + Agreement Import`.
 
## Scope
 
- Implement tenant-specific carrier contract overrides used by SHIP detection.
- Add agreement import pipeline for carrier contract CSVs.
- Keep behavior backward-compatible with existing fallback chain.
 
## Constraints
 
- No breaking API/response changes.
- Keep fallback path safe: tenant override -> `ref.carrier_rules` -> hardcoded defaults.
- Preserve existing detector behavior when tenant config is absent.
 
## Slice 1: Read Path + Fallback Chain
 
- [x] Extend detector context for tenant carrier override inputs.
- [ ] Add active contract-version resolver by `shipDate`.
- [x] Apply tenant overrides in SHIP variance/deadline calculation path.
- [x] Preserve fallback behavior when no tenant override exists.
- [ ] Add tests:
  - [x] Uses tenant dim divisor when present.
  - [x] Uses global/default dim divisor when tenant override absent.
  - [x] Uses tenant claim-window override when present.
  - [x] Falls back to global/default claim-window when absent.
 
## Slice 2: Schema + Migration
 
- [x] Add Prisma models:
  - [x] `CarrierAccount`
  - [x] `CarrierContract`
  - [x] `CarrierContractVersion`
  - [x] `CarrierServiceCode`
- [x] Add migration with rollback note.
- [x] Add follow-up DB guard constraints migration:
  - [x] Check constraints for numeric/date invariants on `carrier_contract_versions`
  - [x] Exclusion constraint preventing overlapping ACTIVE effective-date ranges per contract
- [x] Run migration preflight checks:
  - [x] Ordering against latest `main`
  - [x] Fresh DB apply (`prisma migrate reset --force --skip-seed`)
  - [x] Existing DB apply (`prisma migrate deploy`)
  - [x] Tenant isolation implications documented
 
### Tenant Isolation Notes (Slice 2)
 
- `app.carrier_accounts` is tenant-scoped via `tenant_id`.
- `app.carrier_contracts` and `app.carrier_contract_versions` inherit tenant scope via FK chain:
  `carrier_contract_versions -> carrier_contracts -> carrier_accounts`.
- `app.carrier_service_codes` is global reference/canonicalization data (not tenant-scoped).
- RLS implication: existing P5-A policies do not yet include the new carrier account/contract tables.
  Until a dedicated RLS follow-up migration lands, isolation remains application-enforced (`req.orgId` scoping and
  tenant-bound joins). Add RLS policies before exposing broad read/write surfaces for these tables.
 
## Slice 3: Agreement Import
 
- [x] Add upload endpoint: `POST /api/carrier/agreements/upload`.
- [x] Hash dedupe via `ingestion_batches`.
- [x] Parse CSV -> normalized contract payload.
- [x] Upsert account + contract + version records transactionally.
- [x] Persist source provenance (file hash, retrieval/import time).
 
## Slice 4: Contracts + Docs + Closeout
 
- [x] Add/extend contract tests for new endpoint and read-path behavior.
- [x] Update Postman collection for new carrier agreement endpoint.
- [x] Update `CLAUDE.md` endpoint table.
- [x] Update `docs/EXECUTION_PLAN.md` status and completion notes.
- [x] Add `docs/SESSION_LOG.md` entry with final decisions and deferreds.
 
## Parallel Work (Other Agent)
 
Safe to run in parallel while core branch handles schema/read-path:
 
- [ ] Draft onboarding runbook for P6-F in `docs/runbooks/customer-onboarding.md`.
- [ ] Draft Postman request examples for onboarding/setup endpoints (no code changes).
- [ ] Prepare API contract stubs for P6-F admin setup routes.
 
Do not run in parallel:
 
- Migration lane edits touching P6-E schema files.
- SHIP detector pipeline refactors overlapping fallback chain implementation.