action_build
Diagnostic `nanook::cli::action_build`
Summary
failed to build action for channel `{0}`
Details
When this fires
This wraps an inner action build failure that surfaced while validating the [channels.<name>] block. You'll see it during nanook check (and at nanook run startup) when ActionRegistry::validate rejects the action behind a channel: missing required opts, bad template syntax, or an unknown action kind. The channel name in the message points at the offending [channels.foo] entry.
What to check
The chained inner diagnostic carries the real cause. If it's a template error, the span underlines the bad placeholder. Otherwise open [channels.<name>] and check kind plus required opts.