Re-review flagged that the previous warn-and-skip (aeebdd2) traded a loud
failure for a SILENT prune hazard: against a server too old to return a
workflow's `definition`, pull dropped it with only a stderr warning, exited 0,
and wrote a workflow-less manifest — which a later `apply --prune` uses to
DELETE the server-side workflow (and `pull --force` would clobber a
hand-authored `[[workflows]]` block first).
A live workflow always has ≥1 step (zero-step is rejected at apply), so an
empty `definition` can only mean an out-of-date server. Pull now bails BEFORE
writing anything — consistent with the existing clobber / unsafe-name fail-fast
gates — so nothing partial hits disk and the operator gets an actionable error.
wire_workflow_to_manifest reverts to infallible (the guard upholds its
precondition).
Verified: fmt + clippy -D warnings clean; 5 workflow CLI journeys pass.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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