diff --git a/CLAUDE.md b/CLAUDE.md
index 46d348c..a26fead 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -182,7 +182,7 @@ Frame-based processing element with activation context management.
 
 **Frame Storage:**
 - `frames: list[list[FrameSlotValue]]` -- 2D array [frame_id][slot_idx] holding FrameDest objects and constants
-- `tag_store: dict[int, int]` -- maps act_id → frame_id for activation-to-frame lookup
+- `tag_store: dict[int, tuple[int, int]]` -- maps act_id → (frame_id, lane) for activation-to-frame-and-lane lookup
 - `presence: list[list[bool]]` -- [frame_id][match_slot] for dyadic operand waiting state
 - `port_store: list[list[Optional[Port]]]` -- [frame_id][match_slot] for operand port metadata
 - `free_frames: list[int]` -- pool of unallocated frame IDs
@@ -262,9 +262,9 @@ SimPy process with I-structure (single-assignment) semantics.
 - `System.load(tokens: list[Token])` -- spawns SimPy process that calls send() for each token in order
 
 **PEConfig (emu/types.py):**
-- `pe_id: int`, `iram: dict[int, Instruction] | None`, `frame_count: int = 8`, `frame_slots: int = 64`, `matchable_offsets: int = 8`
+- `pe_id: int`, `iram: dict[int, Instruction] | None`, `frame_count: int = 8`, `frame_slots: int = 64`, `matchable_offsets: int = 8`, `lane_count: int = 4`
 - `initial_frames: Optional[dict[int, list[FrameSlotValue]]]` -- pre-loaded frame data
-- `initial_tag_store: Optional[dict[int, int]]` -- pre-loaded act_id -> frame_id mappings
+- `initial_tag_store: Optional[dict[int, tuple[int, int]]]` -- pre-loaded act_id → (frame_id, lane) mappings
 - `allowed_pe_routes: Optional[set[int]]` -- if set, restrict PE route_table to these PE IDs
 - `allowed_sm_routes: Optional[set[int]]` -- if set, restrict PE sm_routes to these SM IDs
 - `on_event: EventCallback | None` -- if set, PE fires `SimEvent` for every token receive, match, execute, emit, frame alloc/free, slot write, and rejection
@@ -321,7 +321,7 @@ Interactive simulation monitor providing both CLI REPL and web UI for controllin
 **StateSnapshot (monitor/snapshot.py):**
 - `capture(system) -> StateSnapshot` reads live PE/SM state into frozen dataclasses
 - `StateSnapshot(sim_time, next_time, pes: dict[int, PESnapshot], sms: dict[int, SMSnapshot])`
-- `PESnapshot(pe_id, frames, tag_store, presence, port_store, free_frames, iram, input_queue, output_log)` -- frame-based PE state
+- `PESnapshot(pe_id, frames, tag_store, presence, port_store, free_frames, iram, input_queue, output_log)` -- frame-based PE state with tag_store mapping act_id → (frame_id, lane) tuples
 - `SMSnapshot(sm_id, cells: dict[int, SMCellSnapshot], deferred_read, t0_store, input_queue)`
 
 **WebSocket protocol (monitor/server.py):**
diff --git a/monitor/CLAUDE.md b/monitor/CLAUDE.md
index e7831f1..a8bf24b 100644
--- a/monitor/CLAUDE.md
+++ b/monitor/CLAUDE.md
@@ -52,7 +52,7 @@ Commands are frozen dataclasses sent to the backend thread via queue:
 - `__init__.py` -- Public API exports
 - `backend.py` -- `SimulationBackend` class with thread lifecycle and command dispatch
 - `commands.py` -- All command and result frozen dataclasses, `SimCommand` union type
-- `snapshot.py` -- `StateSnapshot`, `PESnapshot` (frame-based: frames, tag_store, presence, port_store, free_frames), `SMSnapshot`, `SMCellSnapshot`, `capture()`
+- `snapshot.py` -- `StateSnapshot`, `PESnapshot` (frame-based: frames, tag_store mapping act_id → (frame_id, lane) tuples, presence, port_store, free_frames), `SMSnapshot`, `SMCellSnapshot`, `capture()`
 - `graph_json.py` -- JSON serialization with execution overlay (extends dfgraph patterns)
 - `server.py` -- `create_app(backend)` FastAPI factory, `ConnectionManager`, WebSocket handler
 - `repl.py` -- `MonitorREPL(cmd.Cmd)` interactive CLI
diff --git a/tests/test_snapshot.py b/tests/test_snapshot.py
index a95fa31..53d616c 100644
--- a/tests/test_snapshot.py
+++ b/tests/test_snapshot.py
@@ -123,7 +123,7 @@ class TestCaptureWithSinglePEAndSM:
             assert isinstance(frame, tuple)
             # Each frame has slots
 
-        # tag_store should be dict mapping act_id to frame_id
+        # tag_store should be dict mapping act_id to (frame_id, lane) tuple
         assert isinstance(pe_snap.tag_store, dict)
 
         # presence should be a tuple of tuples (frame_count x matchable_offsets)
@@ -183,7 +183,7 @@ class TestCaptureWithSinglePEAndSM:
         snapshot = capture(system)
 
         pe_snap = snapshot.pes[0]
-        # tag_store should be a dict mapping act_id to frame_id
+        # tag_store should be a dict mapping act_id to (frame_id, lane) tuple
         assert isinstance(pe_snap.tag_store, dict)
         assert hasattr(pe_snap, 'frames')
         assert hasattr(pe_snap, 'free_frames')