diff --git a/app/models/schemas/recipe.py b/app/models/schemas/recipe.py
index 873f893..422fbb0 100644
--- a/app/models/schemas/recipe.py
+++ b/app/models/schemas/recipe.py
@@ -82,3 +82,48 @@ class RecipeRequest(BaseModel):
     nutrition_filters: NutritionFilters = Field(default_factory=NutritionFilters)
     excluded_ids: list[int] = Field(default_factory=list)
     shopping_mode: bool = False
+
+
+# ── Build Your Own schemas ──────────────────────────────────────────────────
+
+
+class AssemblyRoleOut(BaseModel):
+    """One role slot in a template, as returned by GET /api/recipes/templates."""
+
+    display: str
+    required: bool
+    keywords: list[str]
+    hint: str = ""
+
+
+class AssemblyTemplateOut(BaseModel):
+    """One assembly template, as returned by GET /api/recipes/templates."""
+
+    id: str  # slug, e.g. "burrito_taco"
+    title: str
+    icon: str
+    descriptor: str
+    role_sequence: list[AssemblyRoleOut]
+
+
+class RoleCandidateItem(BaseModel):
+    """One candidate ingredient for a wizard picker step."""
+
+    name: str
+    in_pantry: bool
+    tags: list[str] = Field(default_factory=list)
+
+
+class RoleCandidatesResponse(BaseModel):
+    """Response from GET /api/recipes/template-candidates."""
+
+    compatible: list[RoleCandidateItem] = Field(default_factory=list)
+    other: list[RoleCandidateItem] = Field(default_factory=list)
+    available_tags: list[str] = Field(default_factory=list)
+
+
+class BuildRequest(BaseModel):
+    """Request body for POST /api/recipes/build."""
+
+    template_id: str
+    role_overrides: dict[str, str] = Field(default_factory=dict)
diff --git a/tests/services/recipe/test_assembly_build.py b/tests/services/recipe/test_assembly_build.py
new file mode 100644
index 0000000..0a2a5bf
--- /dev/null
+++ b/tests/services/recipe/test_assembly_build.py
@@ -0,0 +1,106 @@
+"""Tests for Build Your Own recipe assembly schemas."""
+import pytest
+from app.models.schemas.recipe import (
+    AssemblyRoleOut,
+    AssemblyTemplateOut,
+    RoleCandidateItem,
+    RoleCandidatesResponse,
+    BuildRequest,
+)
+
+
+def test_assembly_role_out_schema():
+    """Test AssemblyRoleOut schema creation and field access."""
+    role = AssemblyRoleOut(
+        display="protein",
+        required=True,
+        keywords=["chicken"],
+        hint="Main ingredient"
+    )
+    assert role.display == "protein"
+    assert role.required is True
+    assert role.keywords == ["chicken"]
+    assert role.hint == "Main ingredient"
+
+
+def test_assembly_template_out_schema():
+    """Test AssemblyTemplateOut schema with nested roles."""
+    tmpl = AssemblyTemplateOut(
+        id="burrito_taco",
+        title="Burrito / Taco",
+        icon="🌯",
+        descriptor="Protein, veg, and sauce in a tortilla or over rice",
+        role_sequence=[
+            AssemblyRoleOut(
+                display="base",
+                required=True,
+                keywords=["tortilla"],
+                hint="The wrap"
+            ),
+        ],
+    )
+    assert tmpl.id == "burrito_taco"
+    assert tmpl.title == "Burrito / Taco"
+    assert tmpl.icon == "🌯"
+    assert len(tmpl.role_sequence) == 1
+    assert tmpl.role_sequence[0].display == "base"
+
+
+def test_role_candidate_item_schema():
+    """Test RoleCandidateItem schema with tags."""
+    item = RoleCandidateItem(
+        name="bell pepper",
+        in_pantry=True,
+        tags=["sweet", "vegetable"]
+    )
+    assert item.name == "bell pepper"
+    assert item.in_pantry is True
+    assert "sweet" in item.tags
+
+
+def test_role_candidates_response_schema():
+    """Test RoleCandidatesResponse with compatible and other candidates."""
+    resp = RoleCandidatesResponse(
+        compatible=[
+            RoleCandidateItem(name="bell pepper", in_pantry=True, tags=["sweet"])
+        ],
+        other=[
+            RoleCandidateItem(
+                name="corn",
+                in_pantry=False,
+                tags=["sweet", "starchy"]
+            )
+        ],
+        available_tags=["sweet", "starchy"],
+    )
+    assert len(resp.compatible) == 1
+    assert resp.compatible[0].name == "bell pepper"
+    assert len(resp.other) == 1
+    assert "sweet" in resp.available_tags
+    assert "starchy" in resp.available_tags
+
+
+def test_build_request_schema():
+    """Test BuildRequest schema with template and role overrides."""
+    req = BuildRequest(
+        template_id="burrito_taco",
+        role_overrides={"protein": "chicken", "sauce": "verde"}
+    )
+    assert req.template_id == "burrito_taco"
+    assert req.role_overrides["protein"] == "chicken"
+    assert req.role_overrides["sauce"] == "verde"
+
+
+def test_role_candidates_response_defaults():
+    """Test RoleCandidatesResponse with default factory fields."""
+    resp = RoleCandidatesResponse()
+    assert resp.compatible == []
+    assert resp.other == []
+    assert resp.available_tags == []
+
+
+def test_build_request_defaults():
+    """Test BuildRequest with default role_overrides."""
+    req = BuildRequest(template_id="test_template")
+    assert req.template_id == "test_template"
+    assert req.role_overrides == {}