In a linked worktree basename(git toplevel) is the worktree's name, so the
background child's report was signed `from: dispatch-bg-form` (measured by
the PM on 741ada8) - a mailbox no session holds.
- skills/dispatch: the starter reports by full path with
`coord-send.sh --from <repo> --to <sender>`; board-selftest §19b gains the
check (red on 741ada8) plus a known-negative control that runs the same
predicate against the old "via coord-send" wording.
- coord-send.sh: a DERIVED sender inside a linked worktree exits 2, naming
--from and the repo the worktree belongs to. Chose refusal over a warning
because stderr is where a session least looks and the mail would already be
delivered, and over a silent redirect for the reason the retired
ktg-plugin-marketplace address is rejected rather than redirected.
Linked-ness is git's own test (git-dir != git-common-dir), not ".git is a
file", because a submodule has that too. coord-selftest section 39: 9
checks, 3 red before the fix; controls for submodule, main checkout,
explicit --from and a worktree named like its repo.
- Six other scripts derive identity the same way; named as a bounded gap in
CLAUDE.md, not changed (not ordered).
Suites under /bin/bash 3.2: coord 266, board 497, route 73, orders 116,
guard 54 = 1006 (was 995). npm test 12/12.
Order 20260923T082933Z-466405184-from-.claude.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>