A `workflow`-kind step now starts a nested sub-workflow run instead of a
function. The orchestrator's step processing is restructured into prepare →
dispatch (`Prep`): after the shared context/`when`/input resolution, a
function step runs through the executor as before, while a workflow step:
- checks the nesting depth ceiling (`PICLOUD_WORKFLOW_MAX_DEPTH`; the child
would run at parent depth + 1) — over-deep → the step fails, not infinite;
- resolves the child workflow by name in the run's app scope;
- `start_child_and_park`: in one token-gated tx, seeds a child run (depth + 1,
`parent_run_id`/`parent_step_id` linkage, correlated under the same
`root_execution_id`) and PARKS the parent step (`running`, claim_token
cleared, `child_run_id` set). A parked step is never re-claimed (only `ready`
steps are) nor reclaimed (only *leased* running steps). The token-gated park
runs before the child insert, so a stale claim writes nothing (no orphan).
Each tick first runs `resume_finished_children`: a parent step parked on a
now-terminal child is resolved (child output → parent step output, or child
error → parent step failed) and the parent run advanced — idempotent via a
`status='running'` gate. The child's own steps are claimed by the same global
scan, so nesting is just more runs. A failed sub-workflow honors the parent
step's `on_error`.
Shared plumbing extracted for reuse: `advance_run_tx` (out of
`complete_step_and_advance`) and `seed_run_tx` (out of `start_run`).
Apply-time soft-warn (`workflow_nesting_warnings`, wired into `plan_warnings`):
a workflow that nests into itself — directly or via a mutual cycle within the
bundle — is flagged at plan (bounded by the depth ceiling, but almost always a
bug). Not an error.
Tests: nested output-flows-to-parent + depth-ceiling-fails-the-run (DB-gated,
end-to-end), self/mutual-cycle warning (pure unit). fmt + clippy -D warnings
clean, 449 manager-core lib tests, 13 orchestrator DB tests, 26 CLI journeys
(workflows/apply/plan/prune) green, binary boots.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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