feat(04-01): add ParseInput and ParseOutput schemas

- ParseInput extends StepInput with url field
- ParseOutput extends StepOutput with platform, content_type, content_id, resolved_url, original_url
- Tests for schema validation and inheritance

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

kb_pipeline/schemas.py

@@ -233,3 +233,43 @@ class ASROutput(StepOutput):
     speakers: Optional[List[str]] = Field(
         None, description="说话者列表（仅说话者分离时有值）"
     )
+
+
+# =============================================================================
+# Parse Schemas (Phase 04)
+# =============================================================================
+
+
+class ParseInput(StepInput):
+    """Parse 步骤输入
+
+    继承 StepInput 的基础字段，添加 URL 字段。
+    content_id 和 platform 在解析前是空的，解析后会被填充。
+
+    Attributes:
+        url: 要解析的 URL
+        content_id: 解析后填充的内容 ID（初始为空）
+        platform: 解析后填充的平台名称（初始为空）
+    """
+    url: str = Field(..., min_length=1, description="URL to parse")
+    content_id: str = Field(default="", description="Will be populated after parsing")
+    platform: str = Field(default="", description="Will be populated after parsing")
+
+
+class ParseOutput(StepOutput):
+    """Parse 步骤输出
+
+    继承 StepOutput 的基础字段，添加解析特定字段。
+
+    Attributes:
+        platform: 检测到的平台 (bilibili, zhihu)
+        content_type: 内容类型 (video, article, answer, zhuanlan)
+        content_id: 提取的内容 ID
+        resolved_url: 短链解析后的完整 URL
+        original_url: 用户提供的原始 URL
+    """
+    platform: str = Field(..., description="Detected platform")
+    content_type: str = Field(..., description="Content type (video, article, etc.)")
+    content_id: str = Field(..., description="Extracted content ID")
+    resolved_url: str = Field(..., description="Resolved URL after short link expansion")
+    original_url: str = Field(..., description="Original URL provided by user")

tests/test_pipeline/test_schemas.py

@@ -472,3 +472,100 @@ class TestJSONSerialization:
         restored = WorkflowState.model_validate_json(json_str)
         assert "fetch_metadata" in restored.steps
         assert restored.steps["fetch_metadata"].status == StepStatus.COMPLETED
+
+
+# =============================================================================
+# Parse Schemas Tests (Phase 04-01)
+# =============================================================================
+
+
+class TestParseInput:
+    """测试 ParseInput Schema"""
+
+    def test_parse_input_validates_url_field(self):
+        """ParseInput 必须包含 url 字段，且 min_length=1"""
+        from kb_pipeline.schemas import ParseInput
+
+        # 缺少 url
+        with pytest.raises(ValidationError) as exc_info:
+            ParseInput()
+        assert "url" in str(exc_info.value)
+
+        # 空 url
+        with pytest.raises(ValidationError):
+            ParseInput(url="")
+
+        # 有效 url
+        input_data = ParseInput(url="https://www.bilibili.com/video/BV1xx")
+        assert input_data.url == "https://www.bilibili.com/video/BV1xx"
+
+    def test_parse_input_content_id_default_empty(self):
+        """ParseInput content_id 默认为空字符串"""
+        from kb_pipeline.schemas import ParseInput
+
+        input_data = ParseInput(url="https://www.bilibili.com/video/BV1xx")
+        assert input_data.content_id == ""
+
+    def test_parse_input_platform_default_empty(self):
+        """ParseInput platform 默认为空字符串"""
+        from kb_pipeline.schemas import ParseInput
+
+        input_data = ParseInput(url="https://www.bilibili.com/video/BV1xx")
+        assert input_data.platform == ""
+
+
+class TestParseOutput:
+    """测试 ParseOutput Schema"""
+
+    def test_parse_output_inherits_step_output(self):
+        """ParseOutput 继承 StepOutput 的 success 和 error_message"""
+        from kb_pipeline.schemas import ParseOutput, StepOutput
+
+        output = ParseOutput(
+            success=True,
+            platform="bilibili",
+            content_type="video",
+            content_id="BV1xx",
+            resolved_url="https://www.bilibili.com/video/BV1xx",
+            original_url="https://b23.tv/abc"
+        )
+
+        assert isinstance(output, StepOutput)
+        assert output.success is True
+        assert output.error_message is None
+
+    def test_parse_output_has_required_fields(self):
+        """ParseOutput 包含所有必需字段"""
+        from kb_pipeline.schemas import ParseOutput
+
+        output = ParseOutput(
+            success=True,
+            platform="bilibili",
+            content_type="video",
+            content_id="BV1xx",
+            resolved_url="https://www.bilibili.com/video/BV1xx",
+            original_url="https://b23.tv/abc"
+        )
+
+        assert output.platform == "bilibili"
+        assert output.content_type == "video"
+        assert output.content_id == "BV1xx"
+        assert output.resolved_url == "https://www.bilibili.com/video/BV1xx"
+        assert output.original_url == "https://b23.tv/abc"
+
+    def test_parse_output_with_error(self):
+        """ParseOutput 可以表示失败状态"""
+        from kb_pipeline.schemas import ParseOutput
+
+        output = ParseOutput(
+            success=False,
+            error_message="Unsupported URL format",
+            platform="",
+            content_type="",
+            content_id="",
+            resolved_url="",
+            original_url="https://unknown.com/123"
+        )
+
+        assert output.success is False
+        assert output.error_message == "Unsupported URL format"