Why: the completion doc Q2 requires twelve builtin topologies each with
a scripted-backend conformance; today the engine has only the
standard/leader mode string with no topology abstraction, no loop
re-arm (cycles are fail-closed by design), no in-graph routing, and no
run deadline.
Evidence: GOWORK=off go vet + go test -count=1 green across squad and
all three adapter modules; ten conformance/validation tests:
sequential, parallel, loop-until-field (exact iteration count +
persisted LoopRuns), loop-budget-exhausted (loop_exhausted event, run
still completes), router-selects-branch (loser skipped, run NOT
degraded), router-no-match fail-closed, evaluator-optimizer (draft
re-armed via loop body until verdict=pass), long-running deadline
(pending steps skipped, degraded closeout), unknown/primitive/
unregistered-driver fail-closed, builtin registry completeness (12).
Impact: additive — Topology/Deadline on RunOptions, Topology on
Blueprint, Loop/LoopRuns/Branches/Handoff on StepSpec; empty topology
keeps byte-identical standard behavior; MaxIterations is the total
iteration cap (first run included); router-skipped steps are exempt
from degraded derivation; runParallel now preserves the first specific
RunFailed error instead of re-wrapping via failStep; deadline metadata
uses RFC3339Nano (second-precision RFC3339 truncated sub-second
deadlines into instant expiry).
Refs: Agent-System-Documents#44 (Q2 plan WP1)
weichen