docs: clarify fork gather runtime identity

docs/adr/0006-explicit-fork-and-topology-driven-gather.md

@@ -59,6 +59,21 @@ one token per slot for an activation, waits until all slots are present, then
 merges their lineage-local patches. Its result is a new continuation token that
 preserves combined provenance and can enter another gather.
 
+Runtime identity follows one canonical dependency chain. A runtime scope is one
+workflow invocation and its committed state universe. A lineage belongs to
+exactly one scope and represents one isolated state worldview inside it. An
+execution frame is a schedulable graph cursor that executes against one
+lineage, so the frame's scope and parent lineage are derived through that
+lineage rather than independently stored relationships. Frame ancestry remains
+separate: a parent frame expresses scheduling ownership and block/wake behavior,
+not state ancestry.
+
+Lineages are not owned by frames. A completed branch frame may leave its
+lineage waiting at a gather, and a later continuation frame may execute against
+the lineage produced by a merge. Activation tokens bind a control-flow arrival
+to its lineage plus the correlation and provenance needed by gathers; they do
+not duplicate the lineage's scope membership.
+
 Lineage remains a virtual worldview: committed scope state plus writes visible
 to one branch. Gathering several lineages does not require turning lineage
 ancestry into a multi-parent graph. A partial gather can create an intermediate
@@ -82,6 +97,21 @@ overlap in the asynchronous runtime. Both modes must produce equivalent graph
 semantics. Scheduler order decides when compatible work progresses, never which
 arrivals belong together.
 
+`END` means completion of the current execution frame, not necessarily
+completion of the whole run. The frame owner determines the consequence: a
+root frame completes its workflow invocation, a subgraph root returns to its
+parent boundary, and a foreach item reports completion to its parent barrier.
+For a foreach, normal item-frame completion therefore allows the controller to
+admit or resume the next item without introducing a separate continue node.
+
+General break and race behavior are not part of the first fork/gather design.
+The existing foreach `fail`, `skip`, and `collect` policies describe the
+disposition of runtime item failures; they are distinct from completion
+policies such as first-completed, first-error, or all-completed. A future break
+feature would require an operational signal to the owning foreach and an
+explicit policy for already admitted concurrent items. No `BreakNode` is added
+without that use case and policy.
+
 The current `JoinNode` will not be silently upgraded. Before implementation we
 will verify whether real persisted artifacts use it. With no real compatibility
 obligation, remove it and introduce `GatherNode` cleanly. If persisted callers
@@ -106,6 +136,16 @@ AND across slots and OR within a slot.
 belongs to activation tokens; an intermediate merged worldview can remain a
 child of the compatible inputs' common lineage parent.
 
+**Store scope and parent-lineage identity on every frame.** Rejected because
+those relationships are canonical on the lineage and duplicated frame fields
+can disagree with them. Runtime operations should resolve and validate a
+frame's lineage and scope together.
+
+**Model normal foreach completion as a continue node.** Rejected because
+completion of an item frame already returns control to the owning foreach.
+Break and race semantics remain separate future policies rather than additional
+meanings assigned to ordinary outcomes.
+
 **Reuse or rename `JoinNode`.** Rejected as the default because the existing
 node is a pass-through marker with no barrier contract.
 
@@ -118,6 +158,12 @@ node is a pass-through marker with no barrier contract.
   `(node, outcome)` pair.
 - Checkpoints must persist pending gather arrivals and activation provenance so
   interruption/resume cannot mix loop iterations or subgraph invocations.
+- Runtime operations should resolve a frame, its lineage, and its scope through
+  one internal interface instead of accepting several independently supplied
+  identifiers.
+- Persisted frame state should not duplicate scope or parent-lineage
+  relationships once real checkpoint compatibility has been checked and any
+  required migration has been defined.
 - Trace output must make fork activation, branch identity, gather waiting, and
   merged continuation inspectable without treating scheduler bookkeeping as
   ordinary node output.
@@ -129,8 +175,8 @@ node is a pass-through marker with no barrier contract.
 ## Open Questions
 
 - The exact serialized edge field and authoring name for a gather slot.
-- The minimal activation-context and provenance representation that supports
-  loops, nested forks, subgraphs, partial gathers, and cross-merges.
+- The minimal activation-correlation and provenance representation that
+  supports loops, nested forks, subgraphs, partial gathers, and cross-merges.
 - Whether a gather resumes an existing blocked frame or creates a dedicated
   continuation frame in each topology shape.
 - The trace representation for waiting and merging without excessive internal