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, 0 insertions, 3 deletions

diff --git a/subagents/luatool.lua b/subagents/luatool.lua
index 089c67b..8aaa5c9 100644
--- a/subagents/luatool.lua
+++ b/subagents/luatool.lua
@@ -54,7 +54,6 @@ local CHUNK_NAME = "subagents.lua"
 local M = {}
 
 M.max_jobs = MAX_JOBS
-M.instruction_budget = INSTRUCTION_BUDGET
 
 local function shallow_copy(source, skip)
     local copy = {}
@@ -139,8 +138,6 @@ local function format_return(value)
     return workflow.json_encode(value)
 end
 
-M.format_return = format_return
-
 -- Tool handler for `subagents.lua`. `profiles` is the discovered profile set
 -- from activation; when omitted the workflow API discovers it lazily.
 function M.handle(input, profiles)