FinTS 4.1 Support Status

This document records the current repository state for FinTS 4.1 support. It is a status document, not an implementation plan.

Official protocol references:

Current State

Galanthus has a shared 3.0 / 4.1 backend seam and a partially implemented 4.1 feature surface.

Implemented in the codebase:

shared backend resolution and protocol-family persistence
4.1 account/balance/transaction/holdings substrate
4.1 single transfer and instant transfer substrate
4.1 payment TAN / tan resume path
4.1 standing-order readonly and write paths
conservative 4.1 command-entry activation for the families above

Still incomplete:

full 4.1 direct debit family
full 4.1 batch payment family
request-to-pay
foreign transfers
other newer 4.1-only feature families

Live Validation Status

The bank-specific endpoint used during live testing:

local FinTS 3.0 endpoint

did not provide live evidence of a 4.1/XML dialog path. Successful live requests on that endpoint were still classic FinTS 3.0/binary requests and responses.

So:

the implemented 4.1 code paths exist in the repo
but the live run described here does not count as live 4.1 proof
on that endpoint, the validated live behavior is still primarily FinTS 3.0

Architectural Constraints That Still Matter

The anti-duplication constraints remain in force:

do not fork the shared TAN/resume/VoP model for 4.1
do not duplicate domain types only because 4.1 encodes them differently
keep 3.0 / 4.1 divergence at the wire/backend boundary unless semantics actually differ

See:

fints_4_1_anti_duplication_architecture.md
architecture_reference.md

Next Work

The next 4.1 work should be scoped as feature families, not new execution plans:

direct debit family
batch payment family
advanced 4.1-only feature families

Each new tranche should be documented only as:

current support status
current user-visible limits
final architectural decisions that remain relevant

Completed stage plans and review artifacts should not be kept as long-lived repository documentation.