Module validation 

Validation of user-supplied pipeline overrides in alef.toml.

When a user provides an explicit [lint.<lang>] / [test.<lang>] / [build_commands.<lang>] / [setup.<lang>] / [update.<lang>] / [clean.<lang>] table that sets a main command field, that table must also declare a precondition. The rationale:

• Built-in defaults all declare a command -v <tool> precondition so pipelines degrade gracefully when the underlying tool is missing.
• Custom commands are opaque to alef — only the user knows what the command requires. Forcing an explicit precondition keeps the warn-and-skip behavior intact on systems that can’t run the command.

Tables that only customize before (without overriding the main command) are exempt: the default precondition still applies via the surrounding defaults logic.

Functions

validate_resolved

Validate user-supplied pipeline overrides in a resolved per-crate config.