Master landed the tool-subagent depth budget while this branch was in
flight: the numeric default maxDepth now fails the mount against the
ACP provider's depthLimit: false, so the composition fixture must state
maxDepth: 'provider-managed' — the documented opt-out for a provider
whose recursion budget lives in the child harness. The fixture also
moves off the retired stdio-demo REPL onto the current app-boot driver
pattern (runLoaderSmoke + one-shot cli), and the split isDirectory
statements gain the file-not-a-directory case the single-expression
form used to cover implicitly.
The inheritance branch ran only under hand-mounted plugin tests, and
the with-key e2e always configures an explicit cwd. Add a test-only
cordis.yml (scripted delegating model + the scripted mock ACP child)
booting the stdio app through the real Loader with cwd omitted: the
child proves it ran in — and was announced — the parent session's
workspace, keylessly.