`codeman agent spawn --working-dir "$WT"` with WT empty (a failed
`git worktree add`, say) resolved '' to the caller's cwd and started an
editing worker in the caller's own checkout. An empty or
whitespace-only --working-dir now refuses with exit 4 before any
request.
The emitJson comment names the directory-spawn exception to "the
envelope's data": `{ sessionId, workingDir, created: true, ready }`.
Tests: unit (`''`, spaces, tab: exit 4, no calls) and through the real
argument parser and HTTP transport (nothing sent, exit 4).
Docs: README, api-reference, wiki, SKILL.md (plugin mirror synced) and
the changeset note the refusal.
Aamer Akhter
b26234d6c6