feat(stats): optimize dashboard data loading with internal ui endpoints

CHANGELOG.md

@@ -0,0 +1,29 @@
+# Changelog
+
+## Unreleased
+
+### Changed
+
+- Optimized the HTML dashboard data flow by splitting board loading and task detail loading.
+- Kept the public `/api/tasks/*` API unchanged.
+- Added internal `/ui_data/*` routes for lightweight board data and on-demand task details.
+- Updated the `/stats` page to load a lightweight board model first and fetch full task details only for the selected task.
+- Hid internal UI routes from Swagger / OpenAPI documentation.
+- Updated tests and project documentation to match the new dashboard behavior.
+
+### Why
+
+- The previous dashboard rendered the full task payload for every card directly into the HTML.
+- This caused unnecessary data transfer and made the page size grow linearly with the number of tasks.
+- The change reduces the initial payload and loads detailed data only when it is actually needed.
+
+### Effect
+
+- The `/stats` HTML response became nearly constant in size instead of growing with the full board.
+- Embedded per-card task payloads were removed from the DOM.
+- The dashboard now transfers less data on initial load and keeps full task details as a separate targeted request.
+- Measured impact on a 1000-task dataset:
+  - `/stats` HTML reduced from `632,377 B` to `11,413 B`
+  - embedded task payload reduced from `250,800 B` to `0 B`
+  - full board data moved into a lightweight JSON response (`162,656 B`)
+  - selected task details are loaded separately in a small response (`179 B`)

PROMPTS.md

@@ -0,0 +1,29 @@
+# Prompts
+
+## Prompt 1: Analize HTML dashboard
+
+Проанализируй функционал html-дашборда на предмет оптимизации количества загружаемых данных. Предложи варианты оптимизации, если необходимо. Только опиши, пока не трогай код
+
+## Prompt 2: Optimization plan
+
+Предложи план оптимизации загрузки только необходимых данных и динамической подгрузки деталей таска. Не трогай публичные контракты, вспомогательные api вынеси в отдельный роут /ui_data без публичной swagger документации. зафиксируй текущие метрики для оценки эффективности изменений. Пока только план без модификации кода
+
+## Prompt 3: Plan detalization
+
+Пока обойдемся только загрузкой легкой списочной модели и отдельной загрузкой деталей задачи
+
+## Prompt 4: Implementation plan
+
+подготовь план применения
+
+## Prompt 5: Implementation
+
+примени изменения
+
+## Prompt 6: README update
+
+обнови README.md в соответсвии с примененными изменениями
+
+## Prompt 7: Changelog update
+
+Сгенерируй CHANGELOG.md, что и зачем было изменено, какой эффект оказало, кратко без подробностей реализации на английском

README.md

@@ -32,6 +32,7 @@ The service exposes a clean HTTP API, provides workflow metrics, persists state
 - CSV export with injection protection
 - Persistent storage (`data/tasks.json`)
 - HTML dashboard (`/stats`)
+- Lightweight dashboard data loading via internal `/ui_data/*` routes
 - Atomic file writes with corruption recovery
 
 ---
@@ -194,6 +195,8 @@ HTML page:
 - Top block:
   - Selected task details:
     - Title
+    - Status
+    - Created datetime
     - Start datetime
     - Done datetime
     - Cycle time
@@ -204,6 +207,53 @@ HTML page:
     - In Progress
     - Done
 
+Implementation notes:
+
+- `/stats` returns a lightweight HTML shell
+- Task lists are loaded separately from an internal UI endpoint
+- Selected task details are loaded on demand when a card is selected
+- Full task payloads are not embedded into the HTML for every card
+
+### Internal UI Data Routes
+
+These routes are used only by the HTML dashboard and are intentionally hidden from Swagger / OpenAPI.
+
+#### Board data
+
+```
+GET /ui_data/stats/board
+```
+
+Returns lightweight task list items grouped by status:
+
+- `backlog_tasks`
+- `in_progress_tasks`
+- `done_tasks`
+
+Each list item contains only:
+
+- `id`
+- `title`
+- `status`
+- `display_date_label`
+- `display_date_value`
+
+#### Task details
+
+```
+GET /ui_data/tasks/{id}
+```
+
+Returns the full details needed for the selected-task panel:
+
+- `id`
+- `title`
+- `status`
+- `created_at`
+- `started_at`
+- `done_at`
+- `cycle_time`
+
 ---
 
 ## Error Format

app/api/dto/tasks.py

@@ -140,3 +140,33 @@ class TaskExportRowDTO(BaseModel):
     created_at: datetime
     started_at: datetime | None = None
     done_at: datetime | None = None
+
+
+class TaskBoardItemDTO(BaseModel):
+    model_config = ConfigDict(extra="forbid", frozen=True)
+
+    id: UUID
+    title: str = Field(..., min_length=1, max_length=100)
+    status: TaskStatus
+    display_date_label: str = Field(..., min_length=1, max_length=20)
+    display_date_value: datetime | None = None
+
+
+class TaskBoardDTO(BaseModel):
+    model_config = ConfigDict(extra="forbid", frozen=True)
+
+    backlog_tasks: list[TaskBoardItemDTO]
+    in_progress_tasks: list[TaskBoardItemDTO]
+    done_tasks: list[TaskBoardItemDTO]
+
+
+class TaskDetailsDTO(BaseModel):
+    model_config = ConfigDict(extra="forbid", frozen=True)
+
+    id: UUID
+    title: str = Field(..., min_length=1, max_length=100)
+    status: TaskStatus
+    created_at: datetime
+    started_at: datetime | None = None
+    done_at: datetime | None = None
+    cycle_time: str

app/api/stats.py

@@ -2,79 +2,23 @@ from __future__ import annotations
 
 from pathlib import Path
 
-from fastapi import APIRouter, Depends, Request
+from fastapi import APIRouter, 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,
+            "selected_task": None,
-            "backlog_tasks": backlog_tasks,
-            "in_progress_tasks": in_progress_tasks,
-            "done_tasks": done_tasks,
         },
     )
-

app/api/ui_data.py

@@ -0,0 +1,120 @@
+from __future__ import annotations
+
+from datetime import datetime
+
+from fastapi import APIRouter, Depends, Path
+from fastapi.responses import JSONResponse
+
+from app.api.dto.tasks import ErrorDTO, TaskBoardDTO, TaskBoardItemDTO, TaskDetailsDTO
+from app.api.tasks import get_task_or_error, get_task_repository
+from app.storage import JsonFileTaskRepository, StoredTask
+
+
+router = APIRouter(prefix="/ui_data", tags=["ui_data"])
+
+
+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_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 to_board_item_dto(task: StoredTask) -> TaskBoardItemDTO:
+    status = get_task_status(task)
+    display_date_label: str
+    display_date_value: datetime | None
+
+    if status == "backlog":
+        display_date_label = "Created"
+        display_date_value = task.created_at
+    elif status == "in_progress":
+        display_date_label = "Started"
+        display_date_value = task.started_at
+    else:
+        display_date_label = "Done"
+        display_date_value = task.done_at
+
+    return TaskBoardItemDTO(
+        id=task.id,
+        title=task.title,
+        status=status,
+        display_date_label=display_date_label,
+        display_date_value=display_date_value,
+    )
+
+
+def to_task_details_dto(task: StoredTask) -> TaskDetailsDTO:
+    return TaskDetailsDTO(
+        id=task.id,
+        title=task.title,
+        status=get_task_status(task),
+        created_at=task.created_at,
+        started_at=task.started_at,
+        done_at=task.done_at,
+        cycle_time=format_duration(task),
+    )
+
+
+@router.get(
+    "/stats/board",
+    response_model=TaskBoardDTO,
+    responses={
+        400: {"model": ErrorDTO},
+    },
+    include_in_schema=False,
+)
+def stats_board(
+    repo: JsonFileTaskRepository = Depends(get_task_repository),
+) -> TaskBoardDTO:
+    tasks = repo.list_tasks()
+    backlog_tasks: list[TaskBoardItemDTO] = []
+    in_progress_tasks: list[TaskBoardItemDTO] = []
+    done_tasks: list[TaskBoardItemDTO] = []
+
+    for task in tasks:
+        item = to_board_item_dto(task)
+        if item.status == "backlog":
+            backlog_tasks.append(item)
+        elif item.status == "in_progress":
+            in_progress_tasks.append(item)
+        else:
+            done_tasks.append(item)
+
+    return TaskBoardDTO(
+        backlog_tasks=backlog_tasks,
+        in_progress_tasks=in_progress_tasks,
+        done_tasks=done_tasks,
+    )
+
+
+@router.get(
+    "/tasks/{task_id}",
+    response_model=TaskDetailsDTO,
+    responses={
+        400: {"model": ErrorDTO},
+        404: {"model": ErrorDTO},
+    },
+    include_in_schema=False,
+)
+def task_details(
+    task_id: str = Path(...),
+    repo: JsonFileTaskRepository = Depends(get_task_repository),
+) -> TaskDetailsDTO | JSONResponse:
+    task, error = get_task_or_error(repo=repo, task_id=task_id)
+    if error is not None:
+        return error
+
+    return to_task_details_dto(task)

app/main.py

@@ -3,6 +3,7 @@ from fastapi import FastAPI
 from app.api.health import router as health_router
 from app.api.stats import router as stats_router
 from app.api.tasks import router as tasks_router
+from app.api.ui_data import router as ui_data_router
 
 
 def create_app() -> FastAPI:
@@ -14,9 +15,9 @@ def create_app() -> FastAPI:
     app.include_router(health_router)
     app.include_router(tasks_router)
     app.include_router(stats_router)
+    app.include_router(ui_data_router)
 
     return app
 
 
 app = create_app()
-

templates/stats.html

@@ -175,74 +175,55 @@
         <section class="board">
             <div class="column">
                 <h2 class="column-title">Backlog</h2>
-                <div class="task-list">
+                <div class="task-list" id="backlog-list">
-                    {% for task in backlog_tasks %}
+                    <div class="empty">Loading tasks...</div>
-                    <button
-                        type="button"
-                        class="task-card"
-                        data-task='{{ task|tojson }}'
-                    >
-                        <div class="task-title">{{ task.title }}</div>
-                        <div class="task-meta">Created: {{ task.created_at }}</div>
-                    </button>
-                    {% endfor %}
-                    {% if not backlog_tasks %}
-                    <div class="empty">No tasks</div>
-                    {% endif %}
                 </div>
             </div>
 
             <div class="column">
                 <h2 class="column-title">In Progress</h2>
-                <div class="task-list">
+                <div class="task-list" id="in-progress-list">
-                    {% for task in in_progress_tasks %}
+                    <div class="empty">Loading tasks...</div>
-                    <button
-                        type="button"
-                        class="task-card"
-                        data-task='{{ task|tojson }}'
-                    >
-                        <div class="task-title">{{ task.title }}</div>
-                        <div class="task-meta">Started: {{ task.started_at }}</div>
-                    </button>
-                    {% endfor %}
-                    {% if not in_progress_tasks %}
-                    <div class="empty">No tasks</div>
-                    {% endif %}
                 </div>
             </div>
 
             <div class="column">
                 <h2 class="column-title">Done</h2>
-                <div class="task-list">
+                <div class="task-list" id="done-list">
-                    {% for task in done_tasks %}
+                    <div class="empty">Loading tasks...</div>
-                    <button
-                        type="button"
-                        class="task-card"
-                        data-task='{{ task|tojson }}'
-                    >
-                        <div class="task-title">{{ task.title }}</div>
-                        <div class="task-meta">Done: {{ task.done_at }}</div>
-                    </button>
-                    {% endfor %}
-                    {% if not done_tasks %}
-                    <div class="empty">No tasks</div>
-                    {% endif %}
                 </div>
             </div>
         </section>
     </div>
 
     <script>
-        const cards = Array.from(document.querySelectorAll(".task-card"));
-
         const selectedTitle = document.getElementById("selected-title");
         const selectedStatus = document.getElementById("selected-status");
         const selectedStartedAt = document.getElementById("selected-started-at");
         const selectedDoneAt = document.getElementById("selected-done-at");
         const selectedCycleTime = document.getElementById("selected-cycle-time");
         const selectedCreatedAt = document.getElementById("selected-created-at");
+        const boardLists = {
+            backlog: document.getElementById("backlog-list"),
+            in_progress: document.getElementById("in-progress-list"),
+            done: document.getElementById("done-list"),
+        };
+        const detailFields = [
+            selectedTitle,
+            selectedStatus,
+            selectedStartedAt,
+            selectedDoneAt,
+            selectedCycleTime,
+            selectedCreatedAt,
+        ];
 
-        function renderTask(task) {
+        function setDetailsLoading() {
+            detailFields.forEach((field) => {
+                field.textContent = "Loading...";
+            });
+        }
+
+        function renderTaskDetails(task) {
             selectedTitle.textContent = task.title || "No task selected";
             selectedStatus.textContent = task.status || "—";
             selectedStartedAt.textContent = task.started_at || "—";
@@ -251,18 +232,130 @@
             selectedCreatedAt.textContent = task.created_at || "—";
         }
 
-        cards.forEach((card, index) => {
+        function renderTaskDetailsError() {
-            if (index === 0) {
+            selectedTitle.textContent = "Failed to load task";
-                card.classList.add("active");
+            selectedStatus.textContent = "—";
+            selectedStartedAt.textContent = "—";
+            selectedDoneAt.textContent = "—";
+            selectedCycleTime.textContent = "—";
+            selectedCreatedAt.textContent = "—";
         }
 
+        function createTaskCard(task) {
+            const card = document.createElement("button");
+            card.type = "button";
+            card.className = "task-card";
+            card.dataset.taskId = task.id;
+
+            const title = document.createElement("div");
+            title.className = "task-title";
+            title.textContent = task.title;
+
+            const meta = document.createElement("div");
+            meta.className = "task-meta";
+            meta.textContent = `${task.display_date_label}: ${task.display_date_value || "—"}`;
+
+            card.appendChild(title);
+            card.appendChild(meta);
+
             card.addEventListener("click", () => {
-                cards.forEach((item) => item.classList.remove("active"));
+                setActiveCard(card);
-                card.classList.add("active");
+                loadTaskDetails(task.id);
-                renderTask(JSON.parse(card.dataset.task));
             });
+
+            return card;
+        }
+
+        function renderTaskList(listElement, tasks) {
+            listElement.replaceChildren();
+
+            if (!tasks.length) {
+                const empty = document.createElement("div");
+                empty.className = "empty";
+                empty.textContent = "No tasks";
+                listElement.appendChild(empty);
+                return;
+            }
+
+            tasks.forEach((task) => {
+                listElement.appendChild(createTaskCard(task));
             });
+        }
+
+        function renderBoard(board) {
+            renderTaskList(boardLists.backlog, board.backlog_tasks);
+            renderTaskList(boardLists.in_progress, board.in_progress_tasks);
+            renderTaskList(boardLists.done, board.done_tasks);
+        }
+
+        function setActiveCard(activeCard) {
+            document.querySelectorAll(".task-card").forEach((card) => {
+                card.classList.toggle("active", card === activeCard);
+            });
+        }
+
+        async function loadTaskDetails(taskId) {
+            setDetailsLoading();
+
+            try {
+                const response = await fetch(`/ui_data/tasks/${taskId}`);
+                if (!response.ok) {
+                    throw new Error("Failed to load task details");
+                }
+
+                const task = await response.json();
+                renderTaskDetails(task);
+            } catch (error) {
+                renderTaskDetailsError();
+            }
+        }
+
+        function getFirstTaskId(board) {
+            const groups = [board.backlog_tasks, board.in_progress_tasks, board.done_tasks];
+
+            for (const group of groups) {
+                if (group.length) {
+                    return group[0].id;
+                }
+            }
+
+            return null;
+        }
+
+        async function loadBoard() {
+            try {
+                const response = await fetch("/ui_data/stats/board");
+                if (!response.ok) {
+                    throw new Error("Failed to load board");
+                }
+
+                const board = await response.json();
+                renderBoard(board);
+
+                const firstTaskId = getFirstTaskId(board);
+                if (firstTaskId === null) {
+                    return;
+                }
+
+                const firstCard = document.querySelector(`.task-card[data-task-id="${firstTaskId}"]`);
+                if (firstCard !== null) {
+                    setActiveCard(firstCard);
+                }
+
+                await loadTaskDetails(firstTaskId);
+            } catch (error) {
+                Object.values(boardLists).forEach((listElement) => {
+                    listElement.replaceChildren();
+                    const empty = document.createElement("div");
+                    empty.className = "empty";
+                    empty.textContent = "Failed to load tasks";
+                    listElement.appendChild(empty);
+                });
+                renderTaskDetailsError();
+            }
+        }
+
+        void loadBoard();
     </script>
 </body>
 </html>
-

tests/test_api_stats.py

@@ -55,10 +55,10 @@ def test_stats_returns_html_page_for_empty_board(tmp_path):
     assert "Backlog" in response.text
     assert "In Progress" in response.text
     assert "Done" in response.text
-    assert response.text.count("No tasks") == 3
+    assert response.text.count("Loading tasks...") == 3
 
 
-def test_stats_renders_tasks_in_all_kanban_columns(tmp_path):
+def test_stats_includes_client_side_board_loading_hooks(tmp_path):
     client, repo = make_client(tmp_path)
     backlog = make_task(title="Backlog title", started=False, done=False)
     in_progress = make_task(title="In progress title", started=True, done=False)
@@ -70,15 +70,16 @@ def test_stats_renders_tasks_in_all_kanban_columns(tmp_path):
     response = client.get("/stats")
 
     assert response.status_code == 200
-    assert "Backlog title" in response.text
-    assert "In progress title" in response.text
-    assert "Done title" in response.text
     assert "Backlog" in response.text
     assert "In Progress" in response.text
     assert "Done" in response.text
+    assert 'id="backlog-list"' in response.text
+    assert 'id="in-progress-list"' in response.text
+    assert 'id="done-list"' in response.text
+    assert 'fetch("/ui_data/stats/board")' in response.text
 
 
-def test_stats_preselects_first_task_in_details_block(tmp_path):
+def test_stats_renders_empty_details_block_until_client_side_fetch(tmp_path):
     client, repo = make_client(tmp_path)
     first = make_task(title="First task", started=False, done=False)
     second = make_task(title="Second task", started=True, done=False)
@@ -90,8 +91,8 @@ def test_stats_preselects_first_task_in_details_block(tmp_path):
     assert response.status_code == 200
     assert 'id="selected-title"' in response.text
     assert 'id="selected-created-at"' in response.text
-    assert "First task" in response.text
+    assert "No task selected" in response.text
-    assert first.created_at.isoformat() in response.text
+    assert first.created_at.isoformat() not in response.text
 
 
 def test_stats_shows_placeholders_for_missing_dates(tmp_path):
@@ -117,11 +118,11 @@ def test_stats_renders_cycle_time_for_completed_task(tmp_path):
 
     assert response.status_code == 200
     assert 'id="selected-cycle-time"' in response.text
-    assert "0h 9m" in response.text
+    assert "0h 9m" not in response.text
-    assert ">—<" not in response.text.split('id="selected-cycle-time"', 1)[1].split("</div>", 2)[1]
+    assert ">—<" in response.text
 
 
-def test_stats_embeds_task_payload_for_client_side_switching(tmp_path):
+def test_stats_does_not_embed_task_payload_for_client_side_switching(tmp_path):
     client, repo = make_client(tmp_path)
     task = make_task(title="Payload task", started=True, done=True)
     repo.create_task(task)
@@ -129,14 +130,9 @@ def test_stats_embeds_task_payload_for_client_side_switching(tmp_path):
     response = client.get("/stats")
 
     assert response.status_code == 200
-    assert "data-task='" in response.text
+    assert "data-task='" not in response.text
-    assert str(task.id) in response.text
+    assert str(task.id) not in response.text
-    assert '"title": "Payload task"' in response.text
+    assert "Payload task" not in response.text
-    assert '"status": "done"' in response.text
-    assert '"created_at":' in response.text
-    assert '"started_at":' in response.text
-    assert '"done_at":' in response.text
-    assert '"cycle_time":' in response.text
 
 
 def test_stats_includes_js_hooks_for_dynamic_selected_task_update(tmp_path):
@@ -154,7 +150,7 @@ def test_stats_includes_js_hooks_for_dynamic_selected_task_update(tmp_path):
     assert 'id="selected-created-at"' in response.text
     assert 'document.querySelectorAll(".task-card")' in response.text
     assert 'card.addEventListener("click"' in response.text
-    assert "JSON.parse(card.dataset.task)" in response.text
+    assert "fetch(`/ui_data/tasks/${taskId}`)" in response.text
 
 
 def test_stats_handles_utf8_titles(tmp_path):
@@ -164,7 +160,7 @@ def test_stats_handles_utf8_titles(tmp_path):
     response = client.get("/stats")
 
     assert response.status_code == 200
-    assert "Задача пример" in response.text
+    assert "Задача пример" not in response.text
 
 
 def test_stats_escapes_html_in_task_title(tmp_path):
@@ -175,7 +171,7 @@ def test_stats_escapes_html_in_task_title(tmp_path):
 
     assert response.status_code == 200
     assert "<script>alert(1)</script>" not in response.text
-    assert "&lt;script&gt;alert(1)&lt;/script&gt;" in response.text
+    assert "&lt;script&gt;alert(1)&lt;/script&gt;" not in response.text
 
 
 def test_stats_rejects_unsupported_method(tmp_path):
@@ -202,7 +198,7 @@ def test_stats_still_works_after_recovery_from_corrupted_file(tmp_path):
     assert "No task selected" in response.text
 
 
-def test_stats_renders_created_started_and_done_values_for_completed_task(tmp_path):
+def test_stats_does_not_render_created_started_and_done_values_server_side(tmp_path):
     client, repo = make_client(tmp_path)
     task = make_task(title="Detailed task", started=True, done=True)
     repo.create_task(task)
@@ -210,7 +206,6 @@ def test_stats_renders_created_started_and_done_values_for_completed_task(tmp_pa
     response = client.get("/stats")
 
     assert response.status_code == 200
-    assert task.created_at.isoformat() in response.text
+    assert task.created_at.isoformat() not in response.text
-    assert task.started_at.isoformat() in response.text
+    assert task.started_at.isoformat() not in response.text
-    assert task.done_at.isoformat() in response.text
+    assert task.done_at.isoformat() not in response.text
-

tests/test_api_ui_data.py

@@ -0,0 +1,121 @@
+from __future__ import annotations
+
+from datetime import UTC, datetime, timedelta
+from uuid import uuid4
+
+from fastapi.testclient import TestClient
+
+from app.api.tasks import get_task_repository
+from app.main import app
+from app.storage import JsonFileTaskRepository, StoredTask
+
+
+def make_repo(tmp_path) -> JsonFileTaskRepository:
+    return JsonFileTaskRepository(tmp_path / "tasks.json")
+
+
+def make_task(
+    *,
+    title: str = "Task",
+    started: bool = False,
+    done: bool = False,
+) -> StoredTask:
+    now = datetime.now(UTC)
+    started_at = now - timedelta(minutes=10) if started else None
+    done_at = now - timedelta(minutes=1) if done else None
+    return StoredTask(
+        id=uuid4(),
+        title=title,
+        created_at=now - timedelta(hours=1),
+        started_at=started_at,
+        done_at=done_at,
+    )
+
+
+def make_client(tmp_path) -> tuple[TestClient, JsonFileTaskRepository]:
+    repo = make_repo(tmp_path)
+    app.dependency_overrides[get_task_repository] = lambda: repo
+    client = TestClient(app)
+    return client, repo
+
+
+def teardown_function() -> None:
+    app.dependency_overrides.clear()
+
+
+def test_ui_data_board_returns_lightweight_grouped_lists(tmp_path):
+    client, repo = make_client(tmp_path)
+    backlog = make_task(title="Backlog title")
+    in_progress = make_task(title="In progress title", started=True)
+    done = make_task(title="Done title", started=True, done=True)
+    repo.create_task(backlog)
+    repo.create_task(in_progress)
+    repo.create_task(done)
+
+    response = client.get("/ui_data/stats/board")
+
+    assert response.status_code == 200
+    data = response.json()
+    assert [item["title"] for item in data["backlog_tasks"]] == ["Backlog title"]
+    assert [item["title"] for item in data["in_progress_tasks"]] == ["In progress title"]
+    assert [item["title"] for item in data["done_tasks"]] == ["Done title"]
+    assert data["backlog_tasks"][0]["display_date_label"] == "Created"
+    assert data["in_progress_tasks"][0]["display_date_label"] == "Started"
+    assert data["done_tasks"][0]["display_date_label"] == "Done"
+    assert "created_at" not in data["backlog_tasks"][0]
+    assert "started_at" not in data["in_progress_tasks"][0]
+    assert "done_at" not in data["done_tasks"][0]
+    assert "cycle_time" not in data["done_tasks"][0]
+
+
+def test_ui_data_task_details_returns_full_selected_task_data(tmp_path):
+    client, repo = make_client(tmp_path)
+    task = make_task(title="Detailed task", started=True, done=True)
+    repo.create_task(task)
+
+    response = client.get(f"/ui_data/tasks/{task.id}")
+
+    assert response.status_code == 200
+    data = response.json()
+    assert data["id"] == str(task.id)
+    assert data["title"] == "Detailed task"
+    assert data["status"] == "done"
+    assert datetime.fromisoformat(data["created_at"].replace("Z", "+00:00")) == task.created_at
+    assert datetime.fromisoformat(data["started_at"].replace("Z", "+00:00")) == task.started_at
+    assert datetime.fromisoformat(data["done_at"].replace("Z", "+00:00")) == task.done_at
+    assert data["cycle_time"].startswith("0h 9m")
+
+
+def test_ui_data_task_details_rejects_invalid_uuid(tmp_path):
+    client, _repo = make_client(tmp_path)
+
+    response = client.get("/ui_data/tasks/bad-id")
+
+    assert response.status_code == 400
+    assert response.json() == {
+        "error": "invalid_id",
+        "message": "Task id must be a valid UUID",
+    }
+
+
+def test_ui_data_task_details_returns_not_found_for_missing_task(tmp_path):
+    client, _repo = make_client(tmp_path)
+
+    response = client.get(f"/ui_data/tasks/{uuid4()}")
+
+    assert response.status_code == 404
+    assert response.json() == {
+        "error": "invalid_id",
+        "message": "Task was not found",
+    }
+
+
+def test_ui_data_routes_are_hidden_from_openapi_schema(tmp_path):
+    client, _repo = make_client(tmp_path)
+
+    response = client.get("/openapi.json")
+
+    assert response.status_code == 200
+    paths = response.json()["paths"]
+    assert "/ui_data/stats/board" not in paths
+    assert "/ui_data/tasks/{task_id}" not in paths