Adds maa_join_and_fund($rule_id, $bridge, $amount), so a funder joins a rule and funds the derived agent wallet in a single transaction instead of a join followed by a separate transfer. Either both legs commit or neither does, so activation can no longer strand a joined-but-unfunded wallet.

The node half of the atomic-activation ask:

resolves: https://github.com/trufnetwork/truf-network/issues/1399

A kwil transaction runs exactly one action, so the SDKs cannot compose join + transfer atomically on the client — the two legs can only share a transaction inside one on-chain action. The joinAndFundAgentAddress SDK wrapper that exposes this (and closes #1399) is the follow-up.

What is here

• internal/migrations/054-maa-join-fund.sql — the composite action. Leg 1 delegates to maa_join (all its guards apply: unknown rule, creator-self-join, duplicate join). Leg 2 debits the funder and credits the fresh wallet through 049's existing bridge dispatcher. The whole body runs in the route's nested transaction, so any failure rolls back both legs.
• tests/streams/maa/join_and_fund_test.go — happy path, input validation, atomicity (insufficient balance and bad bridge each roll the join back), and duplicate-join plus a second funder deriving a distinct wallet.

Design notes

• Bridge-agnostic, no .prod.sql twin. The action names no bridge; it only calls 049's dispatcher, whose mainnet twin already remaps the bridge branches. A scan confirms no bridge alias appears in the file.
• Fund-free, like the other MAA setup actions — no wrapper fee, no transaction event. Top-ups after activation keep using the per-bridge transfer actions.
• Never allow-list this action in a rule (header carries the warning): unlike the fund-free maa_join it moves funds, so through the maa_exec route an owner could self-strand into a keyless nested wallet. A restricted agent is blocked by the transfer guard, so no untrusted party can strand or steal; this is a wallet-signed activation call, not an agent action.

Worth a look

• The amount guard is two separate ifs, not IS NULL OR <= 0. The engine's OR returns NULL for TRUE OR NULL rather than TRUE, so the combined form skips the guard on a NULL amount and lets it fall through to the transfer. The same dead pattern exists in 049's withdraw guard (atomic-safe, but its IS NULL half never fires) — left untouched here, flagged for a follow-up.

Testing

Full tests/streams/maa package green, including the four new tests. New migration parses (kwil-cli utils parse).

Summary by CodeRabbit

• New Features

  • Added an atomic join-and-fund action for modular agent addresses.
  • Validates funding amounts and prevents invalid or unauthorized transfers.
  • Returns the derived agent address after successful registration and funding.
  • Rolls back the join if funding fails, preventing partial state changes.

• Tests

  • Added coverage for successful funding, validation errors, rollback behavior, repeat joins, and multiple funders.