Validation-pass fixes; DESIGN.md describes the shipped seam

jobs: a child whose wake pipe cannot be armed is refused up front instead of
started into a state nothing can wake (the luv-less drain loop survives only
for hosts without a loop); a closing child keeps its concurrency slot and
its id's exclusivity until the pump actually exits, so teardown can no
longer over-admit new children or let two turns share one session file.
Resume-metadata reads honor the plain-error contract on a malformed store.

workflow: the built-in schema subset validator is the only validator — the
jsonschema probe made behavior depend on an undeclared rock (see rockspec:
that dependency is deliberately rejected); dead exports and the unreachable
half of the structured-output guard are gone, keeping the empty-arguments
provider case.

DESIGN.md's seam sections now describe the shipped division: binding-level
async jobs and tool control, host-level resolve_model/ExtHost/turn events/
component handles, rock-level policy; protocol bodies run to completion on
the loop thread and cannot yield, cancellation is scoped to the stream that
opened it, and a child's compaction leaves protocol sessions alone.

1 files changed, 7 insertions, 6 deletions

diff --git a/panto-subagents-0.1.0-1.rockspec b/panto-subagents-0.1.0-1.rockspec
index 073ff56..693629e 100644
--- a/panto-subagents-0.1.0-1.rockspec
+++ b/panto-subagents-0.1.0-1.rockspec
@@ -17,12 +17,13 @@
 -- battery, so it is normally already present in the tree this rock installs
 -- into.
 --
--- Deliberately absent: `jsonschema`. It validates structured workflow output
--- when installed, and subagents/workflow.lua uses it if `require` finds it, but
--- it depends on `lrexlib-pcre`, which needs a system PCRE that stock macOS does
--- not have. A failed dependency install would take the whole extension down
--- silently (panto logs and skips a rock that fails to load), so the built-in
--- subset validator is the default and `jsonschema` stays opt-in.
+-- Deliberately absent: `jsonschema`. It depends on `lrexlib-pcre`, which needs
+-- a system PCRE that stock macOS does not have, and a failed dependency install
+-- would take the whole extension down silently (panto logs and skips a rock
+-- that fails to load). subagents/workflow.lua therefore validates structured
+-- workflow output with its own built-in JSON Schema subset and never probes for
+-- the rock: one validator, so the same child output cannot pass on one machine
+-- and fail on another.
 
 rockspec_format = "3.0"
 package = "panto-subagents"