feat: add /api/plan/approve and /api/plan/reject endpoints

Add two new API endpoints enabling the frontend planning review gate:
- POST /api/plan/approve: merges an (optionally edited) DesignPlan into
DesignState, sets phase="approved"
- POST /api/plan/reject: resets DesignState phase to "exploring" and
clears the plan field

Also adds PlanApproveRequest and PlanRejectRequest Pydantic models, and
three new test cases covering phase transitions and plan merging.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/routes.py

@@ -8,6 +8,7 @@ from fastapi import APIRouter
 from fastapi.responses import JSONResponse
 from pydantic import BaseModel, Field
 
+from agents.design_state import DesignState, DesignPlan
 from agents.orchestrator import get_orchestrator
 from agents.prompts import parse_mentions
 from agents.definitions import AGENTS
@@ -43,6 +44,15 @@ class ReportRequest(BaseModel):
     backend: str = "gemini"
 
 
+class PlanApproveRequest(BaseModel):
+    plan: dict = Field(...)
+    design_state: dict = Field(default_factory=dict)
+
+
+class PlanRejectRequest(BaseModel):
+    design_state: dict = Field(default_factory=dict)
+
+
 # ── Endpoints ──────────────────────────────────────────────────────────────
 
 
@@ -149,3 +159,29 @@ async def list_agents():
             for agent in AGENTS.values()
         ]
     })
+
+
+@router.post("/api/plan/approve")
+async def plan_approve(body: PlanApproveRequest):
+    """Approve (possibly edited) design plan, merge into state."""
+    plan = DesignPlan(**body.plan)
+    state = DesignState(**body.design_state)
+    state.part_name = plan.part_name
+    state.description = plan.description
+    state.material = plan.material
+    state.dimensions = dict(plan.dimensions)
+    state.features = list(plan.features)
+    state.constraints = list(plan.constraints)
+    state.axis_recommendation = plan.axis_recommendation
+    state.phase = "approved"
+    state.plan = plan
+    return JSONResponse({"design_state": state.model_dump()})
+
+
+@router.post("/api/plan/reject")
+async def plan_reject(body: PlanRejectRequest):
+    """Reject plan, reset to exploring."""
+    state = DesignState(**body.design_state)
+    state.phase = "exploring"
+    state.plan = None
+    return JSONResponse({"design_state": state.model_dump()})

tests/test_api_routes.py

@@ -125,3 +125,69 @@ class TestAgentsEndpoint:
         assert "role" in agent
         assert "color" in agent
         assert "avatar" in agent
+
+
+class TestPlanApproveEndpoint:
+    def test_approve_sets_phase(self):
+        resp = client.post("/api/plan/approve", json={
+            "plan": {
+                "part_name": "bracket",
+                "description": "test",
+                "material": "aluminum 6061",
+                "dimensions": {"width": 60},
+                "features": ["4x M6 holes"],
+                "constraints": ["min wall 3mm"],
+                "axis_recommendation": "3-axis",
+                "machining_notes": [],
+                "confidence_score": 9.0,
+            },
+            "design_state": {
+                "part_name": "bracket",
+                "material": "steel",
+                "dimensions": {"width": 50},
+                "phase": "planning",
+            },
+        })
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["design_state"]["phase"] == "approved"
+        assert data["design_state"]["material"] == "aluminum 6061"
+        assert data["design_state"]["dimensions"]["width"] == 60
+
+    def test_approve_merges_plan_into_state(self):
+        resp = client.post("/api/plan/approve", json={
+            "plan": {
+                "part_name": "gear",
+                "description": "spur gear",
+                "material": "brass",
+                "dimensions": {"diameter": 40},
+                "features": [],
+                "constraints": [],
+                "axis_recommendation": "3-axis",
+                "machining_notes": ["No undercuts"],
+                "confidence_score": 8.0,
+            },
+            "design_state": {"phase": "planning"},
+        })
+        data = resp.json()
+        assert data["design_state"]["part_name"] == "gear"
+        assert data["design_state"]["plan"]["material"] == "brass"
+
+
+class TestPlanRejectEndpoint:
+    def test_reject_resets_phase(self):
+        resp = client.post("/api/plan/reject", json={
+            "design_state": {
+                "phase": "planning",
+                "material": "aluminum",
+                "plan": {"part_name": "x", "description": "", "material": "aluminum",
+                         "dimensions": {}, "features": [], "constraints": [],
+                         "axis_recommendation": "", "machining_notes": [],
+                         "confidence_score": 5.0},
+            },
+        })
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["design_state"]["phase"] == "exploring"
+        assert data["design_state"]["plan"] is None
+        assert data["design_state"]["material"] == "aluminum"