diff --git a/src/graphon/dsl/entities.py b/src/graphon/dsl/entities.py
index 3871b77..8645a9e 100644
--- a/src/graphon/dsl/entities.py
+++ b/src/graphon/dsl/entities.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from abc import abstractmethod
 from collections.abc import Mapping
 from enum import StrEnum, auto
 from typing import Any, Protocol
@@ -125,4 +126,5 @@ def loadable(self) -> bool:
 
 
 class TypedNodeFactory(Protocol):
+    @abstractmethod
     def create_node(self, node_config: NodeConfigDict) -> Any: ...
diff --git a/src/graphon/file/protocols.py b/src/graphon/file/protocols.py
index c376c02..f42470a 100644
--- a/src/graphon/file/protocols.py
+++ b/src/graphon/file/protocols.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from abc import abstractmethod
 from collections.abc import Generator
 from typing import TYPE_CHECKING, Literal, Protocol
 
@@ -18,8 +19,10 @@ class WorkflowFileRuntimeProtocol(Protocol):
     """
 
     @property
+    @abstractmethod
     def multimodal_send_format(self) -> str: ...
 
+    @abstractmethod
     def http_get(
         self,
         url: str,
@@ -27,10 +30,13 @@ def http_get(
         follow_redirects: bool = True,
     ) -> HttpResponseProtocol: ...
 
+    @abstractmethod
     def storage_load(self, path: str, *, stream: bool = False) -> bytes | Generator: ...
 
+    @abstractmethod
     def load_file_bytes(self, *, file: File) -> bytes: ...
 
+    @abstractmethod
     def resolve_file_url(
         self,
         *,
@@ -38,6 +44,7 @@ def resolve_file_url(
         for_external: bool = True,
     ) -> str | None: ...
 
+    @abstractmethod
     def resolve_upload_file_url(
         self,
         *,
@@ -46,6 +53,7 @@ def resolve_upload_file_url(
         for_external: bool = True,
     ) -> str: ...
 
+    @abstractmethod
     def resolve_tool_file_url(
         self,
         *,
@@ -54,6 +62,7 @@ def resolve_tool_file_url(
         for_external: bool = True,
     ) -> str: ...
 
+    @abstractmethod
     def verify_preview_signature(
         self,
         *,
diff --git a/src/graphon/graph/graph.py b/src/graphon/graph/graph.py
index ac79390..a07dfaa 100644
--- a/src/graphon/graph/graph.py
+++ b/src/graphon/graph/graph.py
@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import logging
+from abc import abstractmethod
 from collections import defaultdict
 from collections.abc import Mapping, Sequence
 from typing import Any, Protocol, final
@@ -27,6 +28,7 @@ class NodeFactory(Protocol):
     allowing for different node creation strategies while maintaining type safety.
     """
 
+    @abstractmethod
     def create_node(self, node_config: NodeConfigDict) -> Node:
         """Create a Node instance from node configuration data.
 
diff --git a/src/graphon/graph/validation.py b/src/graphon/graph/validation.py
index b66def8..712cbf0 100644
--- a/src/graphon/graph/validation.py
+++ b/src/graphon/graph/validation.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from abc import abstractmethod
 from collections.abc import Sequence
 from dataclasses import dataclass
 from typing import TYPE_CHECKING, Protocol
@@ -34,6 +35,7 @@ def __init__(self, issues: Sequence[GraphValidationIssue]) -> None:
 class GraphValidationRule(Protocol):
     """Protocol that individual validation rules must satisfy."""
 
+    @abstractmethod
     def validate(self, graph: Graph) -> Sequence[GraphValidationIssue]:
         """Validate the provided graph and return any discovered issues."""
         ...
diff --git a/src/graphon/graph_engine/command_channels/protocol.py b/src/graphon/graph_engine/command_channels/protocol.py
index 10e3e59..350f6c6 100644
--- a/src/graphon/graph_engine/command_channels/protocol.py
+++ b/src/graphon/graph_engine/command_channels/protocol.py
@@ -4,6 +4,7 @@
 to/from a GraphEngine instance, supporting both local and distributed scenarios.
 """
 
+from abc import abstractmethod
 from typing import Protocol
 
 from ..entities.commands import GraphEngineCommand
@@ -16,6 +17,7 @@ class CommandChannel(Protocol):
     this channel is dedicated to that single execution.
     """
 
+    @abstractmethod
     def fetch_commands(self) -> list[GraphEngineCommand]:
         """Fetch pending commands for this GraphEngine instance.
 
@@ -27,6 +29,7 @@ def fetch_commands(self) -> list[GraphEngineCommand]:
         """
         ...
 
+    @abstractmethod
     def send_command(self, command: GraphEngineCommand) -> None:
         """Send a command to be processed by this GraphEngine instance.
 
diff --git a/src/graphon/graph_engine/command_channels/redis_channel.py b/src/graphon/graph_engine/command_channels/redis_channel.py
index 79312dc..f55b045 100644
--- a/src/graphon/graph_engine/command_channels/redis_channel.py
+++ b/src/graphon/graph_engine/command_channels/redis_channel.py
@@ -6,6 +6,7 @@
 """
 
 import json
+from abc import abstractmethod
 from contextlib import AbstractContextManager
 from typing import Any, Protocol, final
 
@@ -27,18 +28,32 @@
 class RedisPipelineProtocol(Protocol):
     """Minimal Redis pipeline contract used by the command channel."""
 
+    @abstractmethod
     def lrange(self, name: str, start: int, end: int) -> Any: ...
+
+    @abstractmethod
     def delete(self, *names: str) -> Any: ...
+
+    @abstractmethod
     def execute(self) -> list[Any]: ...
+
+    @abstractmethod
     def rpush(self, name: str, *values: str) -> Any: ...
+
+    @abstractmethod
     def expire(self, name: str, time: int) -> Any: ...
+
+    @abstractmethod
     def set(self, name: str, value: str, ex: int | None = None) -> Any: ...
+
+    @abstractmethod
     def get(self, name: str) -> Any: ...
 
 
 class RedisClientProtocol(Protocol):
     """Redis client contract required by the command channel."""
 
+    @abstractmethod
     def pipeline(self) -> AbstractContextManager[RedisPipelineProtocol]: ...
 
 
diff --git a/src/graphon/graph_engine/command_processing/command_processor.py b/src/graphon/graph_engine/command_processing/command_processor.py
index 99903d9..1cadb50 100644
--- a/src/graphon/graph_engine/command_processing/command_processor.py
+++ b/src/graphon/graph_engine/command_processing/command_processor.py
@@ -1,6 +1,7 @@
 """Main command processor for handling external commands."""
 
 import logging
+from abc import abstractmethod
 from collections.abc import Callable
 from typing import Protocol, final
 
@@ -15,6 +16,7 @@
 class CommandHandler[CommandT: GraphEngineCommand](Protocol):
     """Protocol for command handlers."""
 
+    @abstractmethod
     def handle(
         self,
         command: CommandT,
diff --git a/src/graphon/graph_engine/domain/graph_execution.py b/src/graphon/graph_engine/domain/graph_execution.py
index 996de86..a785e63 100644
--- a/src/graphon/graph_engine/domain/graph_execution.py
+++ b/src/graphon/graph_engine/domain/graph_execution.py
@@ -10,7 +10,6 @@
 
 from graphon.entities.pause_reason import PauseReason
 from graphon.enums import NodeState
-from graphon.runtime.graph_runtime_state import GraphExecutionProtocol
 
 from .node_execution import NodeExecution
 
@@ -246,6 +245,3 @@ def loads(self, data: str) -> None:
     def record_node_failure(self) -> None:
         """Increment the count of node failures encountered during execution."""
         self.exceptions_count += 1
-
-
-_: GraphExecutionProtocol = GraphExecution(workflow_id="")
diff --git a/src/graphon/graph_engine/ready_queue/protocol.py b/src/graphon/graph_engine/ready_queue/protocol.py
index 6c53677..c4e4348 100644
--- a/src/graphon/graph_engine/ready_queue/protocol.py
+++ b/src/graphon/graph_engine/ready_queue/protocol.py
@@ -4,6 +4,7 @@
 for execution, supporting both in-memory and persistent storage scenarios.
 """
 
+from abc import abstractmethod
 from collections.abc import Sequence
 from typing import Protocol
 
@@ -35,6 +36,7 @@ class ReadyQueue(Protocol):
     that can be serialized for state storage.
     """
 
+    @abstractmethod
     def put(self, item: str) -> None:
         """Add a node ID to the ready queue.
 
@@ -44,6 +46,7 @@ def put(self, item: str) -> None:
         """
         ...
 
+    @abstractmethod
     def get(self, timeout: float | None = None) -> str:
         """Retrieve and remove a node ID from the queue.
 
@@ -56,6 +59,7 @@ def get(self, timeout: float | None = None) -> str:
         """
         ...
 
+    @abstractmethod
     def task_done(self) -> None:
         """Indicate that a previously retrieved task is complete.
 
@@ -64,6 +68,7 @@ def task_done(self) -> None:
         """
         ...
 
+    @abstractmethod
     def empty(self) -> bool:
         """Check if the queue is empty.
 
@@ -73,6 +78,7 @@ def empty(self) -> bool:
         """
         ...
 
+    @abstractmethod
     def qsize(self) -> int:
         """Get the approximate size of the queue.
 
@@ -82,6 +88,7 @@ def qsize(self) -> int:
         """
         ...
 
+    @abstractmethod
     def dumps(self) -> str:
         """Serialize the queue state to a JSON string for storage.
 
@@ -92,6 +99,7 @@ def dumps(self) -> str:
         """
         ...
 
+    @abstractmethod
     def loads(self, data: str) -> None:
         """Restore the queue state from a JSON string.
 
diff --git a/src/graphon/http/protocols.py b/src/graphon/http/protocols.py
index 505dfa0..9ad6d2a 100644
--- a/src/graphon/http/protocols.py
+++ b/src/graphon/http/protocols.py
@@ -1,3 +1,4 @@
+from abc import abstractmethod
 from collections.abc import Mapping
 from typing import Any, Protocol
 
@@ -6,38 +7,51 @@
 
 class HttpResponseProtocol(Protocol):
     @property
+    @abstractmethod
     def headers(self) -> Mapping[str, str]: ...
 
     @property
+    @abstractmethod
     def content(self) -> bytes: ...
 
     @property
+    @abstractmethod
     def status_code(self) -> int: ...
 
     @property
+    @abstractmethod
     def text(self) -> str: ...
 
     @property
+    @abstractmethod
     def is_success(self) -> bool: ...
 
+    @abstractmethod
     def raise_for_status(self) -> None: ...
 
 
 class HttpClientProtocol(Protocol):
     @property
+    @abstractmethod
     def max_retries_exceeded_error(self) -> type[Exception]: ...
 
     @property
+    @abstractmethod
     def request_error(self) -> type[Exception]: ...
 
+    @abstractmethod
     def get(self, url: str, max_retries: int = ..., **kwargs: Any) -> HttpResponse: ...
 
+    @abstractmethod
     def head(self, url: str, max_retries: int = ..., **kwargs: Any) -> HttpResponse: ...
 
+    @abstractmethod
     def post(self, url: str, max_retries: int = ..., **kwargs: Any) -> HttpResponse: ...
 
+    @abstractmethod
     def put(self, url: str, max_retries: int = ..., **kwargs: Any) -> HttpResponse: ...
 
+    @abstractmethod
     def delete(
         self,
         url: str,
@@ -45,6 +59,7 @@ def delete(
         **kwargs: Any,
     ) -> HttpResponse: ...
 
+    @abstractmethod
     def patch(
         self,
         url: str,
diff --git a/src/graphon/model_runtime/memory/prompt_message_memory.py b/src/graphon/model_runtime/memory/prompt_message_memory.py
index ea2c245..09d5bff 100644
--- a/src/graphon/model_runtime/memory/prompt_message_memory.py
+++ b/src/graphon/model_runtime/memory/prompt_message_memory.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from abc import abstractmethod
 from collections.abc import Sequence
 from typing import Protocol
 
@@ -11,6 +12,7 @@
 class PromptMessageMemory(Protocol):
     """Port for loading memory as prompt messages."""
 
+    @abstractmethod
     def get_history_prompt_messages(
         self,
         max_token_limit: int = DEFAULT_MEMORY_MAX_TOKEN_LIMIT,
diff --git a/src/graphon/model_runtime/model_providers/base/tokenizers/gpt2_tokenizer.py b/src/graphon/model_runtime/model_providers/base/tokenizers/gpt2_tokenizer.py
index 2e33253..5ed4871 100644
--- a/src/graphon/model_runtime/model_providers/base/tokenizers/gpt2_tokenizer.py
+++ b/src/graphon/model_runtime/model_providers/base/tokenizers/gpt2_tokenizer.py
@@ -1,4 +1,5 @@
 import logging
+from abc import abstractmethod
 from collections.abc import Sequence
 from pathlib import Path
 from threading import Lock
@@ -8,6 +9,7 @@
 
 
 class _TokenizerProtocol(Protocol):
+    @abstractmethod
     def encode(self, text: str) -> Sequence[int]: ...
 
 
diff --git a/src/graphon/model_runtime/protocols/llm_runtime.py b/src/graphon/model_runtime/protocols/llm_runtime.py
index 08b52d1..7fad95c 100644
--- a/src/graphon/model_runtime/protocols/llm_runtime.py
+++ b/src/graphon/model_runtime/protocols/llm_runtime.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from abc import abstractmethod
 from collections.abc import Generator, Sequence
 from typing import Any, Literal, Protocol, overload, runtime_checkable
 
@@ -49,6 +50,7 @@ def invoke_llm(
         stream: Literal[True],
     ) -> Generator[LLMResultChunk, None, None]: ...
 
+    @abstractmethod
     def invoke_llm(
         self,
         *,
@@ -90,6 +92,7 @@ def invoke_llm_with_structured_output(
         stream: Literal[True],
     ) -> Generator[LLMResultChunkWithStructuredOutput, None, None]: ...
 
+    @abstractmethod
     def invoke_llm_with_structured_output(
         self,
         *,
@@ -106,6 +109,7 @@ def invoke_llm_with_structured_output(
         | Generator[LLMResultChunkWithStructuredOutput, None, None]
     ): ...
 
+    @abstractmethod
     def get_llm_num_tokens(
         self,
         *,
diff --git a/src/graphon/model_runtime/protocols/moderation_runtime.py b/src/graphon/model_runtime/protocols/moderation_runtime.py
index 8cf6ae9..15e0371 100644
--- a/src/graphon/model_runtime/protocols/moderation_runtime.py
+++ b/src/graphon/model_runtime/protocols/moderation_runtime.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from abc import abstractmethod
 from typing import Any, Protocol, runtime_checkable
 
 from graphon.model_runtime.protocols.provider_runtime import ModelProviderRuntime
@@ -9,6 +10,7 @@
 class ModerationModelRuntime(ModelProviderRuntime, Protocol):
     """Runtime surface required by moderation model wrappers."""
 
+    @abstractmethod
     def invoke_moderation(
         self,
         *,
diff --git a/src/graphon/model_runtime/protocols/provider_runtime.py b/src/graphon/model_runtime/protocols/provider_runtime.py
index 83c35fe..030a32d 100644
--- a/src/graphon/model_runtime/protocols/provider_runtime.py
+++ b/src/graphon/model_runtime/protocols/provider_runtime.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from abc import abstractmethod
 from collections.abc import Sequence
 from typing import Any, Protocol, runtime_checkable
 
@@ -11,8 +12,10 @@
 class ModelProviderRuntime(Protocol):
     """Shared provider discovery, credential validation, and schema lookup."""
 
+    @abstractmethod
     def fetch_model_providers(self) -> Sequence[ProviderEntity]: ...
 
+    @abstractmethod
     def get_provider_icon(
         self,
         *,
@@ -21,6 +24,7 @@ def get_provider_icon(
         lang: str,
     ) -> tuple[bytes, str]: ...
 
+    @abstractmethod
     def validate_provider_credentials(
         self,
         *,
@@ -28,6 +32,7 @@ def validate_provider_credentials(
         credentials: dict[str, Any],
     ) -> None: ...
 
+    @abstractmethod
     def validate_model_credentials(
         self,
         *,
@@ -37,6 +42,7 @@ def validate_model_credentials(
         credentials: dict[str, Any],
     ) -> None: ...
 
+    @abstractmethod
     def get_model_schema(
         self,
         *,
diff --git a/src/graphon/model_runtime/protocols/rerank_runtime.py b/src/graphon/model_runtime/protocols/rerank_runtime.py
index aa3814a..66f70ff 100644
--- a/src/graphon/model_runtime/protocols/rerank_runtime.py
+++ b/src/graphon/model_runtime/protocols/rerank_runtime.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from abc import abstractmethod
 from typing import Any, Protocol, runtime_checkable
 
 from graphon.model_runtime.entities.rerank_entities import (
@@ -13,6 +14,7 @@
 class RerankModelRuntime(ModelProviderRuntime, Protocol):
     """Runtime surface required by rerank model wrappers."""
 
+    @abstractmethod
     def invoke_rerank(
         self,
         *,
@@ -25,6 +27,7 @@ def invoke_rerank(
         top_n: int | None,
     ) -> RerankResult: ...
 
+    @abstractmethod
     def invoke_multimodal_rerank(
         self,
         *,
diff --git a/src/graphon/model_runtime/protocols/speech_to_text_runtime.py b/src/graphon/model_runtime/protocols/speech_to_text_runtime.py
index 8f59a62..ddcae2b 100644
--- a/src/graphon/model_runtime/protocols/speech_to_text_runtime.py
+++ b/src/graphon/model_runtime/protocols/speech_to_text_runtime.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from abc import abstractmethod
 from typing import IO, Any, Protocol, runtime_checkable
 
 from graphon.model_runtime.protocols.provider_runtime import ModelProviderRuntime
@@ -9,6 +10,7 @@
 class SpeechToTextModelRuntime(ModelProviderRuntime, Protocol):
     """Runtime surface required by speech-to-text model wrappers."""
 
+    @abstractmethod
     def invoke_speech_to_text(
         self,
         *,
diff --git a/src/graphon/model_runtime/protocols/text_embedding_runtime.py b/src/graphon/model_runtime/protocols/text_embedding_runtime.py
index 4938ccd..d94f80a 100644
--- a/src/graphon/model_runtime/protocols/text_embedding_runtime.py
+++ b/src/graphon/model_runtime/protocols/text_embedding_runtime.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from abc import abstractmethod
 from typing import Any, Protocol, runtime_checkable
 
 from graphon.model_runtime.entities.text_embedding_entities import (
@@ -13,6 +14,7 @@
 class TextEmbeddingModelRuntime(ModelProviderRuntime, Protocol):
     """Runtime surface required by text and multimodal embedding wrappers."""
 
+    @abstractmethod
     def invoke_text_embedding(
         self,
         *,
@@ -23,6 +25,7 @@ def invoke_text_embedding(
         input_type: EmbeddingInputType,
     ) -> EmbeddingResult: ...
 
+    @abstractmethod
     def invoke_multimodal_embedding(
         self,
         *,
@@ -33,6 +36,7 @@ def invoke_multimodal_embedding(
         input_type: EmbeddingInputType,
     ) -> EmbeddingResult: ...
 
+    @abstractmethod
     def get_text_embedding_num_tokens(
         self,
         *,
diff --git a/src/graphon/model_runtime/protocols/tts_runtime.py b/src/graphon/model_runtime/protocols/tts_runtime.py
index 2b9129a..a1a2388 100644
--- a/src/graphon/model_runtime/protocols/tts_runtime.py
+++ b/src/graphon/model_runtime/protocols/tts_runtime.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from abc import abstractmethod
 from collections.abc import Iterable
 from typing import Any, Protocol, runtime_checkable
 
@@ -10,6 +11,7 @@
 class TTSModelRuntime(ModelProviderRuntime, Protocol):
     """Runtime surface required by text-to-speech model wrappers."""
 
+    @abstractmethod
     def invoke_tts(
         self,
         *,
@@ -20,6 +22,7 @@ def invoke_tts(
         voice: str,
     ) -> Iterable[bytes]: ...
 
+    @abstractmethod
     def get_tts_model_voices(
         self,
         *,
diff --git a/src/graphon/nodes/code/code_node.py b/src/graphon/nodes/code/code_node.py
index a37039d..fbdb2e6 100644
--- a/src/graphon/nodes/code/code_node.py
+++ b/src/graphon/nodes/code/code_node.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from abc import abstractmethod
 from collections.abc import Mapping, Sequence
 from decimal import Decimal
 from textwrap import dedent
@@ -23,6 +24,7 @@
 
 
 class CodeExecutorProtocol(Protocol):
+    @abstractmethod
     def execute(
         self,
         *,
@@ -31,6 +33,7 @@ def execute(
         inputs: Mapping[str, Any],
     ) -> Mapping[str, Any]: ...
 
+    @abstractmethod
     def is_execution_error(self, error: Exception) -> bool: ...
 
 
diff --git a/src/graphon/nodes/llm/file_saver.py b/src/graphon/nodes/llm/file_saver.py
index c6708ae..8053017 100644
--- a/src/graphon/nodes/llm/file_saver.py
+++ b/src/graphon/nodes/llm/file_saver.py
@@ -2,6 +2,7 @@
 
 import mimetypes
 import typing as tp
+from abc import abstractmethod
 
 from graphon.file.constants import DEFAULT_EXTENSION, DEFAULT_MIME_TYPE
 from graphon.file.enums import (
@@ -21,6 +22,7 @@ class LLMFileSaver(tp.Protocol):
     LLM.
     """
 
+    @abstractmethod
     def save_binary_string(
         self,
         data: bytes,
@@ -58,6 +60,7 @@ def save_binary_string(
         """
         raise NotImplementedError
 
+    @abstractmethod
     def save_remote_url(self, url: str, file_type: FileType) -> File:
         """save_remote_url saves the file from a remote url returned by LLM.
 
diff --git a/src/graphon/nodes/llm/protocols.py b/src/graphon/nodes/llm/protocols.py
index 740d039..dd393fb 100644
--- a/src/graphon/nodes/llm/protocols.py
+++ b/src/graphon/nodes/llm/protocols.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from abc import abstractmethod
 from typing import Any, Protocol
 
 from graphon.nodes.llm.runtime_protocols import LLMProtocol
@@ -8,6 +9,7 @@
 class CredentialsProvider(Protocol):
     """Port for loading runtime credentials for a provider/model pair."""
 
+    @abstractmethod
     def fetch(self, provider_name: str, model_name: str) -> dict[str, Any]:
         """Return credentials for the target provider/model or raise a domain error."""
         ...
@@ -16,6 +18,7 @@ def fetch(self, provider_name: str, model_name: str) -> dict[str, Any]:
 class ModelFactory(Protocol):
     """Port for creating prepared graph-facing LLM runtimes for execution."""
 
+    @abstractmethod
     def init_model_instance(
         self,
         provider_name: str,
diff --git a/src/graphon/nodes/llm/runtime_protocols.py b/src/graphon/nodes/llm/runtime_protocols.py
index efafc4c..361a336 100644
--- a/src/graphon/nodes/llm/runtime_protocols.py
+++ b/src/graphon/nodes/llm/runtime_protocols.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from abc import abstractmethod
 from collections.abc import Generator, Mapping, Sequence
 from typing import Any, Literal, Protocol, overload
 
@@ -22,22 +23,29 @@ class LLMProtocol(Protocol):
     """A graph-facing LLM runtime adapter for node execution."""
 
     @property
+    @abstractmethod
     def provider(self) -> str: ...
 
     @property
+    @abstractmethod
     def model_name(self) -> str: ...
 
     @property
+    @abstractmethod
     def parameters(self) -> Mapping[str, Any]: ...
 
     @parameters.setter
+    @abstractmethod
     def parameters(self, value: Mapping[str, Any]) -> None: ...
 
     @property
+    @abstractmethod
     def stop(self) -> Sequence[str] | None: ...
 
+    @abstractmethod
     def get_model_schema(self) -> AIModelEntity: ...
 
+    @abstractmethod
     def get_llm_num_tokens(self, prompt_messages: Sequence[PromptMessage]) -> int: ...
 
     @overload
@@ -62,6 +70,7 @@ def invoke_llm(
         stream: Literal[True],
     ) -> Generator[LLMResultChunk, None, None]: ...
 
+    @abstractmethod
     def invoke_llm(
         self,
         *,
@@ -94,6 +103,7 @@ def invoke_llm_with_structured_output(
         stream: Literal[True],
     ) -> Generator[LLMResultChunkWithStructuredOutput, None, None]: ...
 
+    @abstractmethod
     def invoke_llm_with_structured_output(
         self,
         *,
@@ -107,12 +117,14 @@ def invoke_llm_with_structured_output(
         | Generator[LLMResultChunkWithStructuredOutput, None, None]
     ): ...
 
+    @abstractmethod
     def is_structured_output_parse_error(self, error: Exception) -> bool: ...
 
 
 class PromptMessageSerializerProtocol(Protocol):
     """Port for converting compiled prompt messages into persisted process data."""
 
+    @abstractmethod
     def serialize(
         self,
         *,
@@ -124,4 +136,5 @@ def serialize(
 class RetrieverAttachmentLoaderProtocol(Protocol):
     """Port for resolving retriever segment attachments into graph file references."""
 
+    @abstractmethod
     def load(self, *, segment_id: str) -> Sequence[File]: ...
diff --git a/src/graphon/nodes/protocols.py b/src/graphon/nodes/protocols.py
index 3557792..ea9d9a5 100644
--- a/src/graphon/nodes/protocols.py
+++ b/src/graphon/nodes/protocols.py
@@ -1,3 +1,4 @@
+from abc import abstractmethod
 from collections.abc import Generator, Mapping
 from typing import Any, Protocol
 
@@ -6,10 +7,12 @@
 
 
 class FileManagerProtocol(Protocol):
+    @abstractmethod
     def download(self, f: File, /) -> bytes: ...
 
 
 class ToolFileManagerProtocol(Protocol):
+    @abstractmethod
     def create_file_by_raw(
         self,
         *,
@@ -18,6 +21,7 @@ def create_file_by_raw(
         filename: str | None = None,
     ) -> Any: ...
 
+    @abstractmethod
     def get_file_generator_by_tool_file_id(
         self,
         tool_file_id: str,
@@ -29,6 +33,7 @@ class FileReferenceFactoryProtocol(Protocol):
     format. It enforces approriate permission filtering for the file.
     """
 
+    @abstractmethod
     def build_from_mapping(self, *, mapping: Mapping[str, Any]) -> File: ...
 
 
diff --git a/src/graphon/nodes/runtime.py b/src/graphon/nodes/runtime.py
index 2843e4a..1426cf1 100644
--- a/src/graphon/nodes/runtime.py
+++ b/src/graphon/nodes/runtime.py
@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-import abc
+from abc import abstractmethod
 from collections.abc import Generator, Mapping, Sequence
 from datetime import datetime
 from typing import TYPE_CHECKING, Any, Protocol, runtime_checkable
@@ -26,6 +26,7 @@ class ToolNodeRuntimeProtocol(Protocol):
     translate between graph-owned abstractions and `core.tools` internals.
     """
 
+    @abstractmethod
     def get_runtime(
         self,
         *,
@@ -35,12 +36,14 @@ def get_runtime(
         node_execution_id: str | None = None,
     ) -> ToolRuntimeHandle: ...
 
+    @abstractmethod
     def get_runtime_parameters(
         self,
         *,
         tool_runtime: ToolRuntimeHandle,
     ) -> Sequence[ToolRuntimeParameter]: ...
 
+    @abstractmethod
     def invoke(
         self,
         *,
@@ -50,12 +53,14 @@ def invoke(
         provider_name: str,
     ) -> Generator[ToolRuntimeMessage, None, None]: ...
 
+    @abstractmethod
     def get_usage(
         self,
         *,
         tool_runtime: ToolRuntimeHandle,
     ) -> LLMUsage: ...
 
+    @abstractmethod
     def build_file_reference(self, *, mapping: Mapping[str, Any]) -> Any: ...
 
 
@@ -63,14 +68,14 @@ def build_file_reference(self, *, mapping: Mapping[str, Any]) -> Any: ...
 class HumanInputNodeRuntimeProtocol(Protocol):
     """Workflow-layer adapter for human-input runtime persistence and delivery."""
 
-    @abc.abstractmethod
+    @abstractmethod
     def get_form(
         self,
         *,
         node_id: str,
     ) -> HumanInputFormStateProtocol | None: ...
 
-    @abc.abstractmethod
+    @abstractmethod
     def create_form(
         self,
         *,
@@ -85,6 +90,7 @@ def create_form(
 class HumanInputFormRepositoryBindableRuntimeProtocol(Protocol):
     """Optional capability for runtimes that require explicit repository binding."""
 
+    @abstractmethod
     def with_form_repository(
         self,
         form_repository: object,
@@ -130,22 +136,29 @@ def _normalize_human_input_runtime(
 
 class HumanInputFormStateProtocol(Protocol):
     @property
+    @abstractmethod
     def id(self) -> str: ...
 
     @property
+    @abstractmethod
     def rendered_content(self) -> str: ...
 
     @property
+    @abstractmethod
     def selected_action_id(self) -> str | None: ...
 
     @property
+    @abstractmethod
     def submitted_data(self) -> Mapping[str, Any] | None: ...
 
     @property
+    @abstractmethod
     def submitted(self) -> bool: ...
 
     @property
+    @abstractmethod
     def status(self) -> HumanInputFormStatus: ...
 
     @property
+    @abstractmethod
     def expiration_time(self) -> datetime: ...
diff --git a/src/graphon/runtime/graph_runtime_state.py b/src/graphon/runtime/graph_runtime_state.py
index c4a9221..fd0c2cd 100644
--- a/src/graphon/runtime/graph_runtime_state.py
+++ b/src/graphon/runtime/graph_runtime_state.py
@@ -2,6 +2,7 @@
 
 import importlib
 import json
+from abc import abstractmethod
 from collections.abc import Mapping, Sequence
 from contextlib import AbstractContextManager, nullcontext
 from copy import deepcopy
@@ -25,32 +26,39 @@
 class ReadyQueueProtocol(Protocol):
     """Structural interface required from ready queue implementations."""
 
+    @abstractmethod
     def put(self, item: str) -> None:
         """Enqueue the identifier of a node that is ready to run."""
         ...
 
+    @abstractmethod
     def get(self, timeout: float | None = None) -> str:
         """Return the next node identifier,
         blocking until available or timeout expires.
         """
         ...
 
+    @abstractmethod
     def task_done(self) -> None:
         """Signal that the most recently dequeued node has completed processing."""
         ...
 
+    @abstractmethod
     def empty(self) -> bool:
         """Return True when the queue contains no pending nodes."""
         ...
 
+    @abstractmethod
     def qsize(self) -> int:
         """Approximate the number of pending nodes awaiting execution."""
         ...
 
+    @abstractmethod
     def dumps(self) -> str:
         """Serialize the queue contents for persistence."""
         ...
 
+    @abstractmethod
     def loads(self, data: str) -> None:
         """Restore the queue contents from a serialized payload."""
         ...
@@ -63,18 +71,22 @@ class NodeExecutionProtocol(Protocol):
     retry_count: int
     execution_id: str | None
 
+    @abstractmethod
     def mark_started(self, execution_id: str) -> None:
         """Mark the node execution as started."""
         ...
 
+    @abstractmethod
     def mark_taken(self) -> None:
         """Mark the node execution as successfully completed."""
         ...
 
+    @abstractmethod
     def mark_failed(self, error: str) -> None:
         """Mark the node execution as failed with an error."""
         ...
 
+    @abstractmethod
     def increment_retry(self) -> None:
         """Increment the retry counter for the node execution."""
         ...
@@ -98,52 +110,64 @@ class GraphExecutionProtocol(Protocol):
     pause_reasons: list[PauseReason]
 
     @property
+    @abstractmethod
     def node_executions(self) -> Mapping[str, NodeExecutionProtocol]:
         """Return the persisted node execution state keyed by node id."""
         ...
 
+    @abstractmethod
     def start(self) -> None:
         """Transition execution into the running state."""
         ...
 
+    @abstractmethod
     def complete(self) -> None:
         """Mark execution as successfully completed."""
         ...
 
+    @abstractmethod
     def abort(self, reason: str) -> None:
         """Abort execution in response to an external stop request."""
         ...
 
+    @abstractmethod
     def pause(self, reason: PauseReason) -> None:
         """Pause execution with a recorded reason."""
         ...
 
+    @abstractmethod
     def fail(self, error: Exception) -> None:
         """Record an unrecoverable error and end execution."""
         ...
 
+    @abstractmethod
     def record_node_failure(self) -> None:
         """Increment the count of node failures observed during execution."""
         ...
 
+    @abstractmethod
     def get_or_create_node_execution(self, node_id: str) -> NodeExecutionProtocol:
         """Return the execution entity for a node, creating it when needed."""
         ...
 
     @property
+    @abstractmethod
     def is_paused(self) -> bool:
         """Return whether the execution is currently paused."""
         ...
 
     @property
+    @abstractmethod
     def has_error(self) -> bool:
         """Return whether the execution has recorded an error."""
         ...
 
+    @abstractmethod
     def dumps(self) -> str:
         """Serialize execution state into a JSON payload."""
         ...
 
+    @abstractmethod
     def loads(self, data: str) -> None:
         """Restore execution state from a previously serialized payload."""
         ...
@@ -152,18 +176,22 @@ def loads(self, data: str) -> None:
 class ResponseStreamCoordinatorProtocol(Protocol):
     """Structural interface for response stream coordinator."""
 
+    @abstractmethod
     def register(self, response_node_id: str) -> None:
         """Register a response node so its outputs can be streamed."""
         ...
 
+    @abstractmethod
     def track_node_execution(self, node_id: str, execution_id: str) -> None:
         """Track the current execution id for a node."""
         ...
 
+    @abstractmethod
     def on_edge_taken(self, edge_id: str) -> Sequence[NodeRunStreamChunkEvent]:
         """Update pending response sessions after an edge is taken."""
         ...
 
+    @abstractmethod
     def intercept_event(
         self,
         event: NodeRunStreamChunkEvent | NodeRunSucceededEvent,
@@ -171,10 +199,12 @@ def intercept_event(
         """Translate node events into streamed response events."""
         ...
 
+    @abstractmethod
     def loads(self, data: str) -> None:
         """Restore coordinator state from a serialized payload."""
         ...
 
+    @abstractmethod
     def dumps(self) -> str:
         """Serialize coordinator state for persistence."""
         ...
@@ -188,6 +218,7 @@ class NodeProtocol(Protocol):
     execution_type: NodeExecutionType
     node_type: ClassVar[NodeType]
 
+    @abstractmethod
     def blocks_variable_output(
         self,
         variable_selectors: set[tuple[str, ...]],
@@ -207,14 +238,24 @@ class GraphProtocol(Protocol):
     to the runtime state.
     """
 
-    nodes: Mapping[str, NodeProtocol]
-    edges: Mapping[str, EdgeProtocol]
-    root_node: NodeProtocol
+    @property
+    @abstractmethod
+    def nodes(self) -> Mapping[str, NodeProtocol]: ...
+
+    @property
+    @abstractmethod
+    def edges(self) -> Mapping[str, EdgeProtocol]: ...
+
+    @property
+    @abstractmethod
+    def root_node(self) -> NodeProtocol: ...
 
+    @abstractmethod
     def get_outgoing_edges(self, node_id: str) -> Sequence[EdgeProtocol]: ...
 
 
 class ChildGraphEngineBuilderProtocol(Protocol):
+    @abstractmethod
     def build_child_engine(
         self,
         *,
diff --git a/src/graphon/runtime/graph_runtime_state_protocol.py b/src/graphon/runtime/graph_runtime_state_protocol.py
index 7b5c9ce..f4e1e31 100644
--- a/src/graphon/runtime/graph_runtime_state_protocol.py
+++ b/src/graphon/runtime/graph_runtime_state_protocol.py
@@ -1,3 +1,4 @@
+from abc import abstractmethod
 from collections.abc import Mapping, Sequence
 from typing import Protocol
 
@@ -8,10 +9,12 @@
 class ReadOnlyVariablePool(Protocol):
     """Read-only interface for VariablePool."""
 
+    @abstractmethod
     def get(self, selector: Sequence[str], /) -> Segment | None:
         """Get a variable value (read-only)."""
         ...
 
+    @abstractmethod
     def get_by_prefix(self, prefix: str, /) -> Mapping[str, object]:
         """Get all variables stored under a given node prefix (read-only)."""
         ...
@@ -26,49 +29,59 @@ class ReadOnlyGraphRuntimeState(Protocol):
     """
 
     @property
+    @abstractmethod
     def variable_pool(self) -> ReadOnlyVariablePool:
         """Get read-only access to the variable pool."""
         ...
 
     @property
+    @abstractmethod
     def start_at(self) -> float:
         """Get the start time (read-only)."""
         ...
 
     @property
+    @abstractmethod
     def total_tokens(self) -> int:
         """Get the total tokens count (read-only)."""
         ...
 
     @property
+    @abstractmethod
     def llm_usage(self) -> LLMUsage:
         """Get a copy of LLM usage info (read-only)."""
         ...
 
     @property
+    @abstractmethod
     def outputs(self) -> dict[str, object]:
         """Get a defensive copy of outputs (read-only)."""
         ...
 
     @property
+    @abstractmethod
     def node_run_steps(self) -> int:
         """Get the node run steps count (read-only)."""
         ...
 
     @property
+    @abstractmethod
     def ready_queue_size(self) -> int:
         """Get the number of nodes currently in the ready queue."""
         ...
 
     @property
+    @abstractmethod
     def exceptions_count(self) -> int:
         """Get the number of node execution exceptions recorded."""
         ...
 
+    @abstractmethod
     def get_output(self, key: str, default: object = None) -> object:
         """Get a single output value (returns a copy)."""
         ...
 
+    @abstractmethod
     def dumps(self) -> str:
         """Serialize the runtime state into a JSON snapshot (read-only)."""
         ...
diff --git a/src/graphon/runtime/variable_pool.py b/src/graphon/runtime/variable_pool.py
index 6fe8103..36787c3 100644
--- a/src/graphon/runtime/variable_pool.py
+++ b/src/graphon/runtime/variable_pool.py
@@ -4,7 +4,7 @@
 from collections import defaultdict
 from collections.abc import Mapping, Sequence
 from copy import deepcopy
-from typing import TYPE_CHECKING, Annotated, Any, Self
+from typing import Annotated, Any, Self
 
 from pydantic import BaseModel, ConfigDict, Field, model_validator
 
@@ -371,12 +371,3 @@ def flatten(self, *, unprefixed_node_id: str | None = None) -> Mapping[str, obje
     def empty(cls) -> VariablePool:
         """Create an empty variable pool."""
         return cls()
-
-
-if TYPE_CHECKING:
-    # static assertion to ensure VariablePool implements the
-    # ReadOnlyVariablePool.
-    from .graph_runtime_state_protocol import ReadOnlyVariablePool
-
-    def _assert_readonly_variable_pool(pool: VariablePool) -> ReadOnlyVariablePool:  # pyright: ignore[reportUnusedFunction]
-        return pool
diff --git a/tests/graph_engine/test_response_coordinator.py b/tests/graph_engine/test_response_coordinator.py
index 031ade2..e05536e 100644
--- a/tests/graph_engine/test_response_coordinator.py
+++ b/tests/graph_engine/test_response_coordinator.py
@@ -53,14 +53,22 @@ def __init__(self) -> None:
 
 
 class _TestGraph(GraphProtocol):
-    nodes: dict[str, _TestNode]
-    edges: dict[str, _TestEdge]
-    root_node: _TestNode
-
     def __init__(self, root_node: _TestNode) -> None:
-        self.nodes = {root_node.id: root_node}
-        self.edges: dict[str, _TestEdge] = {}
-        self.root_node = root_node
+        self._nodes = {root_node.id: root_node}
+        self._edges: dict[str, _TestEdge] = {}
+        self._root_node = root_node
+
+    @property
+    def nodes(self) -> dict[str, _TestNode]:
+        return self._nodes
+
+    @property
+    def edges(self) -> dict[str, _TestEdge]:
+        return self._edges
+
+    @property
+    def root_node(self) -> _TestNode:
+        return self._root_node
 
     def get_outgoing_edges(self, node_id: str) -> Sequence[_TestEdge]:
         _ = node_id
diff --git a/tests/test_protocol_abstract_contracts.py b/tests/test_protocol_abstract_contracts.py
new file mode 100644
index 0000000..8537f8b
--- /dev/null
+++ b/tests/test_protocol_abstract_contracts.py
@@ -0,0 +1,132 @@
+from __future__ import annotations
+
+import ast
+import importlib
+import inspect
+from pathlib import Path
+
+import pytest
+
+
+def _is_direct_protocol_class(
+    class_def: ast.ClassDef,
+    *,
+    protocol_aliases: set[str],
+) -> bool:
+    for base in class_def.bases:
+        base_expr = base.value if isinstance(base, ast.Subscript) else base
+        if isinstance(base_expr, ast.Name) and base_expr.id in protocol_aliases:
+            return True
+        if (
+            isinstance(base_expr, ast.Attribute)
+            and isinstance(base_expr.value, ast.Name)
+            and f"{base_expr.value.id}.{base_expr.attr}" in protocol_aliases
+        ):
+            return True
+    return False
+
+
+def _discover_protocol_aliases(parsed: ast.Module) -> set[str]:
+    protocol_aliases = set[str]()
+    typing_aliases: set[str] = set()
+
+    for node in parsed.body:
+        if isinstance(node, ast.ImportFrom) and node.module in {
+            "typing",
+            "typing_extensions",
+        }:
+            for alias in node.names:
+                if alias.name == "Protocol":
+                    protocol_aliases.add(alias.asname or alias.name)
+            continue
+
+        if isinstance(node, ast.Import):
+            for alias in node.names:
+                if alias.name in {"typing", "typing_extensions"}:
+                    typing_aliases.add(alias.asname or alias.name)
+
+    protocol_aliases.update(f"{alias}.Protocol" for alias in typing_aliases)
+    return protocol_aliases
+
+
+def _has_protocol_members(class_def: ast.ClassDef) -> bool:
+    return any(
+        isinstance(member, ast.FunctionDef | ast.AsyncFunctionDef)
+        for member in class_def.body
+    )
+
+
+def _discover_protocol_targets() -> list[type[object]]:
+    src_root = Path(__file__).resolve().parents[1] / "src" / "graphon"
+    protocol_classes: list[type[object]] = []
+
+    for file_path in sorted(src_root.rglob("*.py")):
+        parsed = ast.parse(file_path.read_text())
+        protocol_aliases = _discover_protocol_aliases(parsed)
+        if not protocol_aliases:
+            continue
+
+        module_name = "graphon." + ".".join(
+            file_path.relative_to(src_root).with_suffix("").parts,
+        )
+        module = importlib.import_module(module_name)
+
+        for class_def in [
+            node for node in parsed.body if isinstance(node, ast.ClassDef)
+        ]:
+            if not _is_direct_protocol_class(
+                class_def,
+                protocol_aliases=protocol_aliases,
+            ):
+                continue
+            if not _has_protocol_members(class_def):
+                continue
+            protocol_classes.append(getattr(module, class_def.name))
+
+    protocol_classes.sort(key=lambda cls: (cls.__module__, cls.__qualname__))
+    return protocol_classes
+
+
+def _protocol_member_names(protocol_cls: type[object]) -> list[str]:
+    member_names: list[str] = []
+    for name, value in protocol_cls.__dict__.items():
+        if name.startswith("__") and name.endswith("__"):
+            continue
+        if isinstance(value, property | classmethod | staticmethod):
+            member_names.append(name)
+            continue
+        if inspect.isfunction(value):
+            member_names.append(name)
+    return member_names
+
+
+PROTOCOL_TARGETS = _discover_protocol_targets()
+
+
+def _protocol_id(protocol_cls: type[object]) -> str:
+    return f"{protocol_cls.__module__}.{protocol_cls.__qualname__}"
+
+
+def test_protocol_targets_should_be_discovered() -> None:
+    assert PROTOCOL_TARGETS
+
+
+@pytest.mark.parametrize(
+    "protocol_cls",
+    PROTOCOL_TARGETS,
+    ids=_protocol_id,
+)
+def test_protocol_members_should_be_abstract(protocol_cls: type[object]) -> None:
+    member_names = _protocol_member_names(protocol_cls)
+    # This protects the test from a vacuous pass if discovery and runtime member
+    # detection drift apart. Discovery only targets Protocol classes with
+    # methods, so an empty member list means the test is no longer checking the
+    # contract it claims to check.
+    assert member_names, f"{_protocol_id(protocol_cls)} has no protocol members."
+
+    non_abstract_members = [
+        name
+        for name in member_names
+        if not getattr(protocol_cls.__dict__[name], "__isabstractmethod__", False)
+    ]
+    assert non_abstract_members == []