fix(simulation): PR #176 review round — all 12 findings + 2 recommendations addressed

H1 demux: ShapeProbe defensive multi-shape rejection (union frames now Err, not first-match; +2 tests) and doc claim made honest. H2/T1 SystemIndex.reset_test_state() folded into SimBridge.reset_test_state() (load() inline per autoload rule) + has_pending_request() accessor. H3 no-op tests now assert the replay flag both directions. H4 retry test actually ingests a failure and asserts the retry semantic. H5 error fixture uses the normalized status string. H6 bridge_tcp e2e sends all five frame shapes over real TCP (star-map + city-names buffers asserted). H7 positive replay-on-CONNECTED test via the test_local_bridge test-mode-flip precedent (stub bridge captures + decodes the request bytes). H8/T2 stale PLACEHOLDER doc replaced with the confirmed contract. H9 is_capital doc matches the COALESCE reality. T-r1 demux ceiling written down (next shape = tagged envelope). T-r2 AtlasLayerResponse governance ceiling comment. Lead item: the four cargo-fmt-formatted files from the gate round are now committed (layer_proxy/plugin/bridge-mod/main). H10 note for the record: the 13 snapshot_*.msgpack fixtures in commit 845737617 were regenerated because they were stale against their own generator (pre-existing version-key removal) — verified harmless, no client reads that key.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

client/scripts/protocol/protocol.gd

@@ -774,9 +774,11 @@ static func decode_atlas_layer_response(bytes: PackedByteArray) -> Variant:
 ## road_graph/settlements (T-960): passthrough fields for the L2 road/rail
 ## graph and L3 settlement placements, mirroring the district_grid precedent
 ## (T-1046) — raw decoded maps/arrays, no further client-side reshaping.
-## PLACEHOLDER key names ("road_graph"/"settlements") pending confirmation
-## against dudley-atlas-server's RoadGraphLayer/SettlementLayer field names —
-## this is the one spot to rename if the server picks different keys.
+## Key names "road_graph"/"settlements" are the CONFIRMED wire contract —
+## identical to server/src/atlas/layer_proxy.rs AtlasLayerResponse's field
+## names (pinned 2026-07-14; round-tripped by test_atlas_overlays.gd and the
+## server's msgpack round-trip tests). This remains the one client-side spot
+## to touch if the contract ever changes.
 static func atlas_response_from_raw(raw: Variant) -> Variant:
 	if not raw is Dictionary or not raw.has("status"):
 		return null