fix scheduling reasoning on physical cores directly

.agents/invariants/PIPELINE_SCHEDULING_INVARIANT.md

@@ -18,17 +18,20 @@ Dynamic function inputs are stage-zero sources. Any operation that directly
 consumes one must belong to stage 0. A later stage may consume that data only
 through an explicit result forwarded by the preceding stage.
 
-Each logical core belongs to exactly one stage capacity range before physical
-placement. Those ranges cover every core but may have different sizes when the
-initial partitioner predicts a lower maximum stage interval. Physical placement
-may map a stage to arbitrary core IDs using the injected target topology.
+PEFT assigns physical cores using the injected target topology and their actual
+resident-weight capacity. Pipeline stage capacities cover every physical core
+and may have different sizes when the partitioner predicts a lower maximum
+stage interval. Before stage-local packing, the layout groups physical cores
+by bidirectional link cost; stage cores need not have consecutive IDs. Packing
+scores transfers on those physical links, and communication realization must
+preserve the resulting core identities.
 Synchronization and deferred transfers consume the explicit stage identity;
 they must not infer it from a physical core number after placement.
 
 ## Ownership
 
-Logical PEFT remains pipeline-agnostic. Stage partitioning is the first phase
-of pipeline scheduling and owns this invariant. It must construct a valid
+Physical PEFT supplies the initial placement. Stage partitioning is the first
+phase of pipeline scheduling and owns stage adjacency. It must construct a valid
 operation-level partition before physical-core packing. Operations split for
 physical capacity retain one shared stage identity. Repacking may move work
 only within its assigned stage. Deferred-transfer planning and
@@ -44,7 +47,7 @@ Before scheduled materialization, verify that:
 - every direct dynamic-function-input consumer belongs to stage 0;
 - every compute-graph edge stays within a stage or advances exactly one stage;
 - every stage-local resident-weight set fits its assigned physical core; and
-- stage capacities cover all logical cores exactly once; and
+- stage capacities cover all physical cores exactly once; and
 - physical placement is a permutation of all target cores.
 
 Pipeline scheduling tests must include an uneven physical-core layout and a