Rust Errors

Use this when the problem is not "how do I return an error" but "what failure shape belongs at this boundary?"

Working stance

• Keep library errors typed and inspectable.
• Let binaries optimise for reporting and context.
• Panic only for broken invariants, not expected failure.
• If a caller could reasonably recover, return an error rather than panic! or .expect().
• Add context where it helps a future reader act.
• Separate retryable, terminal, and caller-bug failures early.

Decision surface