🏦 CBS Mock Stub

Mock Core Banking System for UPP integration testing. Type a "magic" account number into UPP to get a behaviour with zero setup.

Magic account-number prefixes

Prefix	Behaviour
`INV*`	Account not found (404)
`FRZ*`	Debit freeze (DR) → payment rejected
`CRF*`	Credit freeze (CR) → reject when used as beneficiary
`LOW*`	Tiny balance (1) → insufficient funds → RJCT
`ZERO*`	Zero balance → IGNR for split-% scheduled instructions (poller gets 0, skips autoPayments). For immediate instructions use fund-then-drain instead.
`RJCT*`	Always RJCT
`PARK*`	Always PARK (409)
`FAIL2, FAIL3`	Fail N times (500) then succeed
`anything else`	Healthy ACTIVE account, large balance

Valid values

Freeze codes: DR, CR, FULL
Payment outcomes: ACSC, ACSP, REVW, PARK, RJCT

UPP-facing routes

`GET /api/v1/accounts?accountNumber=`	Balance check
`GET /diy-accounts-proxy`	Account onboarding
`POST /api/autoPayments`	Payment execution

Admin / tester routes

`GET/POST/PATCH/DELETE /admin/accounts[/:id]`	Account CRUD
`POST /admin/accounts/bulk`	Create many accounts at once
`POST /admin/accounts/:id/outcome`	Set payment outcome / failCount
`GET/DELETE /admin/transactions`	Audit log of payments UPP sent
`GET /admin/snapshot` · `POST /admin/snapshot/restore`	Save / restore full account state
`GET /admin/scenarios` · `POST /admin/scenarios/:name/load`	Load a named preset
`GET /admin/validations` · `POST /admin/validations/:id/toggle`	List / toggle IL validation rules
`GET /health`	Health check

IL Validation routes

`POST /api/v1/validate`	Validate a payment — body: `{ payments:[...], type:"quick"\|"full", isImmediate:true }`
`POST /api/v1/validate/bulk`	Validate a batch — same body shape, balance check enabled
`POST /api/v1/lookup`	Enrich payment with CBS account details

Payment field reference (by payment mode)

Field	Path in payload	NEFT	RTGS	IMPS	IFT	SWIFT
Payment mode	`PaymentDetails.paymentMode`	NEFT	RTGS	IMPS	IFT	SWIFT
Amount	`amt`	✅	✅	✅	✅	✅
Currency	`currency`	INR	INR	INR	INR	any
Sender account	`from.id`	✅	✅	✅	✅	✅
Beneficiary account	`PaymentDetails.to`	✅	✅	✅	✅	✅
Beneficiary name	`PaymentDetails.accountName`	✅	✅	✅	✅	✅
IFSC	`PaymentDetails.ifscCode`	required	required	✅	❌	❌
SWIFT BIC	`PaymentDetails.swiftCode`	❌	❌	❌	❌	required
Sender LEI	`PaymentDetails.leiUniqueId`	≥₹50cr	≥₹50cr	❌	❌	❌
Receiver LEI	`PaymentDetails.beneficiaryLeiUniqueId`	≥₹50cr	≥₹50cr	❌	❌	❌
Debit narration	`debitNarration`	✅	✅	✅	✅	✅
Credit narration	`creditNarration`	✅	✅	✅	✅	✅
Beneficiary country	`PaymentDetails.beneficiaryCountry`	IN	IN	IN	IN	any
IBAN	`PaymentDetails.iban`	❌	❌	❌	❌	✅

How to request a new validation rule

Tell Claude (via MCP) using this template — no code needed, Claude writes it for you:

RULE NAME:       UPPER_SNAKE_CASE name

DESCRIPTION:     What this rule checks and why (plain English)

APPLIES TO:
  Path:          Quick (A) | Full (B) | Both
  Payment mode:  All | NEFT | RTGS | IMPS | IFT | SWIFT

CONDITION TO FAIL:
  - Field to check: (see field reference above)
  - Fails when:
  - Exceptions: (e.g. "only when amount > X", "not for reversals")

ERROR MESSAGE:   Message shown when the rule fails

EXAMPLE PASS:    { amt: 100, PaymentDetails: { paymentMode: "NEFT", ifscCode: "HDFC0001234" } }
EXAMPLE FAIL:    { amt: 100, PaymentDetails: { paymentMode: "NEFT", ifscCode: "" } }

Claude calls add_validation → rule is live immediately, no redeploy needed.
Use list_validations to see all rules · toggle_validation to switch any on/off.