diff --git a/pyproject.toml b/pyproject.toml
index 34480b3..5b9bc5a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -13,6 +13,8 @@ dependencies = [
   "pyyaml>=6.0",
   "openpyxl>=3.1",
   "python-docx>=1.0",
+  "httpx>=0.28",
+  "jinja2>=3.1",
 ]
 
 [project.optional-dependencies]
diff --git a/src/genesis/inference/__init__.py b/src/genesis/inference/__init__.py
new file mode 100644
index 0000000..c191f84
--- /dev/null
+++ b/src/genesis/inference/__init__.py
@@ -0,0 +1,23 @@
+"""Genesis 推理引擎（统一 LLM 调用入口）。"""
+
+from .types import ChatMessage, ChatResult, Prompt, StructuredResult, TokenUsage
+from .exceptions import (
+    LLMError,
+    LLMNetworkError,
+    LLMNotConfiguredError,
+    LLMResponseError,
+    LLMTimeoutError,
+)
+
+__all__ = [
+    "ChatMessage",
+    "ChatResult",
+    "Prompt",
+    "StructuredResult",
+    "TokenUsage",
+    "LLMError",
+    "LLMNetworkError",
+    "LLMNotConfiguredError",
+    "LLMResponseError",
+    "LLMTimeoutError",
+]
\ No newline at end of file
diff --git a/src/genesis/inference/exceptions.py b/src/genesis/inference/exceptions.py
new file mode 100644
index 0000000..8fed13d
--- /dev/null
+++ b/src/genesis/inference/exceptions.py
@@ -0,0 +1,21 @@
+from __future__ import annotations
+
+
+class LLMError(Exception):
+    """LLM 调用相关的异常基类（api-design §7 映射基底）"""
+
+
+class LLMNetworkError(LLMError):
+    """网络失败 / 5xx 重试耗尽（可重试语义）"""
+
+
+class LLMTimeoutError(LLMError):
+    """LLM 调用超时（api-error: LLM_TIMEOUT 502）"""
+
+
+class LLMNotConfiguredError(LLMError):
+    """Key / 模型缺失（api-error: LLM_NOT_CONFIGURED 503）"""
+
+
+class LLMResponseError(LLMError):
+    """响应结构损坏（JSON 解析失败等）"""
\ No newline at end of file
diff --git a/src/genesis/inference/types.py b/src/genesis/inference/types.py
new file mode 100644
index 0000000..2e8e472
--- /dev/null
+++ b/src/genesis/inference/types.py
@@ -0,0 +1,52 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import Any, Literal
+
+
+@dataclass
+class TokenUsage:
+    """一次 LLM 调用的 token 用量（可观测性事件/统计用）"""
+    input_tokens: int = 0
+    output_tokens: int = 0
+
+
+@dataclass
+class ChatMessage:
+    """Chat Completions 消息"""
+    role: Literal["system", "user", "assistant"]
+    content: str
+
+
+@dataclass
+class ChatResult:
+    """chat() 的返回值"""
+    text: str
+    model: str
+    prompt_version: str
+    usage: TokenUsage
+    duration_ms: int
+    status: Literal["ok", "fallback", "failed"]
+    error: str | None = None
+
+
+@dataclass
+class StructuredResult:
+    """chat_structured() 的返回值（补丁 1：含 status 字段）"""
+    data: dict
+    raw_text: str
+    parse_attempts: int
+    model: str
+    prompt_version: str
+    usage: TokenUsage
+    duration_ms: int
+    status: Literal["ok", "fallback", "parse_error", "failed"]
+    error: str | None = None
+
+
+@dataclass
+class Prompt:
+    """Prompt 模板条目（name+version 唯一）"""
+    name: str
+    version: str
+    template: str
\ No newline at end of file
diff --git a/tests/test_inference_errors.py b/tests/test_inference_errors.py
new file mode 100644
index 0000000..7020f70
--- /dev/null
+++ b/tests/test_inference_errors.py
@@ -0,0 +1,21 @@
+import pytest
+
+from genesis.inference.exceptions import (
+    LLMError,
+    LLMNetworkError,
+    LLMNotConfiguredError,
+    LLMResponseError,
+    LLMTimeoutError,
+)
+
+
+def test_error_hierarchy():
+    assert issubclass(LLMNetworkError, LLMError)
+    assert issubclass(LLMTimeoutError, LLMError)
+    assert issubclass(LLMNotConfiguredError, LLMError)
+    assert issubclass(LLMResponseError, LLMError)
+
+
+def test_error_message_roundtrip():
+    e = LLMTimeoutError("timeout!")
+    assert str(e) == "timeout!"
\ No newline at end of file
diff --git a/tests/test_inference_types.py b/tests/test_inference_types.py
new file mode 100644
index 0000000..682fe78
--- /dev/null
+++ b/tests/test_inference_types.py
@@ -0,0 +1,40 @@
+from genesis.inference.types import ChatMessage, ChatResult, Prompt, StructuredResult, TokenUsage
+
+
+def test_token_usage_defaults():
+    u = TokenUsage()
+    assert u.input_tokens == 0 and u.output_tokens == 0
+
+
+def test_chat_message_roles():
+    assert ChatMessage(role="system", content="x").content == "x"
+
+
+def test_chat_result_defaults():
+    r = ChatResult(
+        text="t", model="m", prompt_version="v1", usage=TokenUsage(),
+        duration_ms=10, status="ok",
+    )
+    assert r.status == "ok" and r.error is None
+
+
+def test_structured_result_status_ok():
+    r = StructuredResult(
+        data={"a": 1}, raw_text='{"a":1}', parse_attempts=1, model="m",
+        prompt_version="v1", usage=TokenUsage(), duration_ms=10, status="ok",
+    )
+    assert r.data == {"a": 1} and r.raw_text == '{"a":1}'
+
+
+def test_structured_result_status_parse_error():
+    r = StructuredResult(
+        data={}, raw_text="NOT JSON", parse_attempts=3, model="m",
+        prompt_version="v1", usage=TokenUsage(), duration_ms=50,
+        status="parse_error", error="bad json",
+    )
+    assert r.status == "parse_error" and r.error == "bad json"
+
+
+def test_prompt_fields():
+    p = Prompt(name="writer", version="v2", template="章节 {{chapter}}")
+    assert p.name == "writer" and p.version == "v2"
\ No newline at end of file