feat(backend): add Pydantic schemas

backend/src/schemas/pattern.py

@@ -0,0 +1,126 @@
+from typing import Any
+from uuid import UUID
+
+from pydantic import BaseModel
+
+
+class PatternBase(BaseModel):
+    """Base pattern schema."""
+
+    name: str
+    slug: str
+    description: str | None = None
+    when_to_use: str | None = None
+    pattern_type: str | None = None
+    display_order: int | None = None
+
+
+class PatternResponse(PatternBase):
+    """Pattern response schema."""
+
+    id: UUID
+    question_count: int = 0
+
+    model_config = {"from_attributes": True}
+
+
+class PatternListResponse(BaseModel):
+    """Response for pattern list."""
+
+    items: list[PatternResponse]
+
+
+class PatternDetailResponse(PatternBase):
+    """Pattern detail with related questions."""
+
+    id: UUID
+    question_count: int = 0
+
+    model_config = {"from_attributes": True}
+
+
+# Tutorial-specific schemas
+
+
+class CommonMistake(BaseModel):
+    """A common mistake when using a pattern."""
+
+    title: str
+    description: str
+    fix: str | None = None
+
+
+class PatternVariation(BaseModel):
+    """A variation of a pattern."""
+
+    name: str
+    description: str
+    example: str | None = None
+
+
+class RelatedPattern(BaseModel):
+    """Brief info about a related pattern."""
+
+    slug: str
+    name: str
+    description: str | None = None
+
+
+class LearningQuestion(BaseModel):
+    """Question for learning progression."""
+
+    id: UUID
+    title: str
+    slug: str
+    difficulty: str
+    leetcode_id: int | None = None
+    is_optimal: bool = False
+
+
+class LearningProgression(BaseModel):
+    """Curated learning path for a pattern."""
+
+    warmup: list[LearningQuestion]
+    core: list[LearningQuestion]
+    challenge: list[LearningQuestion]
+
+
+class VisualizationExample(BaseModel):
+    """Interactive visualization example for a pattern."""
+
+    id: str
+    title: str
+    input: dict[str, Any] | None = None
+    code: str
+    steps: list[dict[str, Any]]
+
+
+class PatternTutorialResponse(PatternBase):
+    """Full pattern tutorial with all educational content."""
+
+    id: UUID
+    question_count: int = 0
+
+    # Tutorial content
+    metaphor: str | None = None
+    core_concept: str | None = None
+    visualization: str | None = None
+    code_template: str | None = None
+
+    # Structured data
+    recognition_signals: list[str] | None = None
+    common_mistakes: list[CommonMistake] | None = None
+    variations: list[PatternVariation] | None = None
+    related_patterns: list[RelatedPattern] | None = None
+    prerequisite_patterns: list[RelatedPattern] | None = None
+
+    # Difficulty level (1-5)
+    difficulty_level: int | None = None
+
+    # Learning progression
+    learning_progression: LearningProgression | None = None
+
+    # Interactive visualization examples
+    visualization_examples: list[VisualizationExample] | None = None
+
+    model_config = {"from_attributes": True}