> ## Documentation Index
> Fetch the complete documentation index at: https://docs.starknet.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Transaction flow

> Action compilation, ordering constraints, and per-token balance invariants

## Pipeline

1. Build client-side actions.
2. Generate proof over compiled server-side actions.
3. Submit (directly or via paymaster).
4. Contract verifies and executes.

## Why fixed ordering exists

Ordering (`SetViewingKey -> OpenChannel -> OpenSubchannel -> Deposit -> UseNote -> CreateNote -> Withdraw`) reduces state-machine ambiguity and closes classes of ordering bugs where the same semantic operation could be encoded in multiple inconsistent sequences.

## Per-token temporary balance

Within one transaction, each token keeps a temporary balance:

* `Deposit` and `UseNote` increase it.
* `CreateNote` and `Withdraw` decrease it.

Invariant:

* it must never go negative during execution,
* and **must end at 0** at the end of transaction.

"Must end at 0" means all temporary inflows are fully matched by outflows in that transaction; no unaccounted residual value remains.