Expand description
Error type for the newt-coder plugin.
Mirrors the failure-mode taxonomy in
~/workspaces/knowledge/board/drake/2026-05-29_newt-coder-failure-mode-taxonomy.md:
workspace scan failure, prompt-too-large guard trip, malformed
emission, file-write failure, and inference-backend errors are
distinct variants so callers (and tests) can pattern-match.