Trim the salvaged suite to the behaviour contracts: a picker exception or Ctrl+C leaves
config.yaml's model exactly as snapshotted (parametrized), and an absent active_provider
stays absent through snapshot+restore. The mock-dispatch tests (asserting calls into our own
helpers) are dropped. evals/cli_fallback_add_picker_error.py drives the real
`hermes fallback add` under a Linux PTY into an ordinary picker OSError and checks the
persisted model: stranded on base, restored after.
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