# Bug 10650 — `libeufin-bank passwd` prompts for a password even when no username is given

- **Repository:** `libeufin` (module: libeufin-bank)
- **Category:** libeufin-bank / Severity: tweak
- **Patch:** [`libeufin.diff`](./libeufin.diff)
- **Upstream:** https://bugs.gnunet.org/view.php?id=10650

## Core issue

Running the `passwd` subcommand without the required `username` argument
interactively asks for (and confirms) a new password *first*, and only
*afterwards* fails with the missing-argument error:

```
$ libeufin-bank passwd
Password:
Repeat password for confirmation:
Usage: libeufin-bank passwd [<options>] <username> [<password>]
Error: missing argument <username>
```

The user is forced to type a password twice for a command that was always
going to be rejected. The validation of the required `username` argument
should happen before any interactive prompting.

## Root cause

In `libeufin-bank/src/main/kotlin/tech/libeufin/bank/cli/ChangePw.kt`, the
optional `password` argument supplied its default via Clikt's `defaultLazy`,
and that lambda performed the interactive `ConfirmationPrompt`:

```kotlin
private val username by argument("username", ...)
private val password by argument("password", ...)
    .defaultLazy("prompt") {
        ... ConfirmationPrompt.create(...).ask()!!   // prompts here
    }
```

Clikt evaluates argument defaults during **argument finalization**, which runs
*before* the framework raises `MissingArgument` for the absent required
`username`. So the prompt fires as a side effect of finalizing `password`,
ahead of the `username` check. Prompting from inside an argument default is the
core mistake: a default value's computation should be free of user-visible side
effects that depend on other arguments being present.

## Resolution

Make `password` a plain optional argument (no side-effecting default) and move
the interactive prompt into `run()`, which Clikt only invokes **after** all
required arguments have been successfully parsed and validated:

```kotlin
private val password by argument("password", ...).optional()

private fun promptPassword(): String { /* ConfirmationPrompt … */ }

override fun run() = cliCmd(logger) {
    val rawPassword = password ?: promptPassword()
    bankConfig(config).withDb { db, cfg ->
        val password = rawPassword.checkPw(cfg.pwdCheckQuality)
        ...
    }
}
```

With this change, invoking `passwd` with no `username` exits immediately with
the "missing argument <username>" error and never prompts. When `username`
*is* provided but `password` is omitted, the prompt behaves exactly as before.
The prompt is also now performed before the DB connection is opened, so no
connection is held open across the interactive wait.

The prompting logic itself (the `ConfirmationPrompt` with hidden input and
match confirmation) is preserved verbatim, just relocated into the
`promptPassword()` helper.

## Verification

- `.optional()` is the standard Clikt argument modifier and is already used the
  same way in a sibling command in this module
  (`cli/CreateAccount.kt:76`), so the API and the existing wildcard import
  `com.github.ajalt.clikt.parameters.arguments.*` cover it.
- A full Kotlin compile could **not** be run in this environment: the offline
  Gradle build aborts before compilation because it cannot fetch the
  `org.jetbrains.kotlin.jvm` Gradle plugin (no network / plugin not cached).
  The change is therefore validated by code review against the existing Clikt
  usage patterns in the same module rather than by compilation.