feat(taskflow): add core task API, storage persistence, csv export, stats page, and test coverage

app/api/stats.py

@@ -0,0 +1,80 @@
+from __future__ import annotations
+
+from pathlib import Path
+
+from fastapi import APIRouter, Depends, Request
+from fastapi.responses import HTMLResponse
+from fastapi.templating import Jinja2Templates
+
+from app.api.tasks import get_task_repository
+from app.storage import JsonFileTaskRepository, StoredTask
+
+
+router = APIRouter(tags=["stats"])
+
+templates = Jinja2Templates(directory=str(Path(__file__).resolve().parents[2] / "templates"))
+
+
+def get_task_status(task: StoredTask) -> str:
+    if task.done_at is not None:
+        return "done"
+    if task.started_at is not None:
+        return "in_progress"
+    return "backlog"
+
+
+def format_dt(value: object) -> str:
+    if value is None:
+        return "—"
+    return str(value)
+
+
+def format_duration(task: StoredTask) -> str:
+    if task.started_at is None or task.done_at is None:
+        return "—"
+
+    delta = task.done_at - task.started_at
+    total_seconds = int(delta.total_seconds())
+    hours, remainder = divmod(total_seconds, 3600)
+    minutes, seconds = divmod(remainder, 60)
+    return f"{hours}h {minutes}m {seconds}s"
+
+
+def serialize_task(task: StoredTask) -> dict[str, str]:
+    return {
+        "id": str(task.id),
+        "title": task.title,
+        "status": get_task_status(task),
+        "created_at": task.created_at.isoformat(),
+        "started_at": task.started_at.isoformat() if task.started_at is not None else "",
+        "done_at": task.done_at.isoformat() if task.done_at is not None else "",
+        "cycle_time": format_duration(task),
+    }
+
+
+@router.get("/stats", response_class=HTMLResponse)
+def stats_page(
+    request: Request,
+    repo: JsonFileTaskRepository = Depends(get_task_repository),
+) -> HTMLResponse:
+    tasks = repo.list_tasks()
+
+    backlog_tasks = [serialize_task(task) for task in tasks if get_task_status(task) == "backlog"]
+    in_progress_tasks = [serialize_task(task) for task in tasks if get_task_status(task) == "in_progress"]
+    done_tasks = [serialize_task(task) for task in tasks if get_task_status(task) == "done"]
+
+    selected_task = None
+    if tasks:
+        selected_task = serialize_task(tasks[0])
+
+    return templates.TemplateResponse(
+        request=request,
+        name="stats.html",
+        context={
+            "selected_task": selected_task,
+            "backlog_tasks": backlog_tasks,
+            "in_progress_tasks": in_progress_tasks,
+            "done_tasks": done_tasks,
+        },
+    )
+