story: DGR-038 Implement isolated shard-local Hot KV State

tests/test_llama_shard_worker_binding.py

@@ -44,3 +44,20 @@ def test_identity_is_loaded_not_stream_supplied_and_health_reports_it():
     assert "model artifact or runtime recipe digest does not match" in source
     assert "resident_bytes" in source
     assert '" range=["' in source
+
+
+def test_hot_kv_is_bounded_and_keyed_by_route_session_and_epoch():
+    engine = (WORKER / "llama_shard_engine.cpp").read_text(encoding="utf-8")
+    header = (WORKER / "llama_shard_engine.h").read_text(encoding="utf-8")
+    service = (WORKER / "shard_service.cpp").read_text(encoding="utf-8")
+    main = (WORKER / "shard_worker_main.cpp").read_text(encoding="utf-8")
+    assert "struct SessionKey" in engine
+    assert "uint64_t route_epoch" in engine
+    assert "llama_init_from_model" in engine
+    assert "llama_memory_seq_rm" in engine
+    assert "EvictExpiredLocked" in engine
+    assert "EvictLruLocked" in engine
+    assert "HotKvStatus::kCacheMiss" in service
+    assert "ERROR_CODE_CACHE_MISS" in service
+    assert "MESHNET_HOT_KV_BUDGET_TOKENS" in main
+    assert "HotKvStep" in header