add pi task extension

pi/extensions/pi-task/README.md

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+# pi-task
+
+A small, session-scoped task list for Pi. It adds one agent tool, `task`, a
+compact widget above the editor, and a progress indicator in the footer.
+
+The tool accepts the complete ordered task list, like Claude's todo tool or
+Codex's plan tool. The agent adds, updates, removes, or reorders tasks by
+submitting a new list. Omitting the list reads the current state; submitting an
+empty list clears it.
+
+Statuses are `pending`, `in_progress`, and `completed`. At most one task can be
+in progress at a time.
+
+State is stored in Pi tool-result details. It survives reloads and compaction,
+follows session branches correctly, and does not create project files. A new Pi
+session starts with an empty list.
+
+While work is active, the widget uses themed symbols and colors to distinguish
+the current task (`●`) from pending tasks (`○`). The footer shows compact
+overall progress. When every task is complete, Pi displays a success
+notification and removes both the widget and footer indicator to reclaim space.
+The completed list remains available in session history.
+
+Run `/tasks` to refresh the task UI manually.

pi/extensions/pi-task/index.ts

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+import type {
+  ExtensionAPI,
+  ExtensionContext,
+  Theme,
+} from "@earendil-works/pi-coding-agent";
+import { StringEnum } from "@earendil-works/pi-ai";
+import { Text } from "@earendil-works/pi-tui";
+import { Type } from "typebox";
+
+type TaskStatus = "pending" | "in_progress" | "completed";
+
+interface Task {
+  text: string;
+  status: TaskStatus;
+}
+
+interface TaskDetails {
+  tasks: Task[];
+}
+
+const TaskParams = Type.Object({
+  tasks: Type.Optional(
+    Type.Array(
+      Type.Object({
+        text: Type.String({ description: "Short, outcome-oriented task description" }),
+        status: StringEnum(["pending", "in_progress", "completed"] as const),
+      }),
+      {
+        description:
+          "Complete ordered task list. Submit the full list to add, update, reorder, or remove tasks. Omit to read it.",
+      },
+    ),
+  ),
+});
+
+function cloneTasks(tasks: Task[]): Task[] {
+  return tasks.map((task) => ({ ...task }));
+}
+
+function formatTask(task: Task): string {
+  const marker = {
+    pending: "○",
+    in_progress: "●",
+    completed: "✓",
+  }[task.status];
+
+  return `${marker} ${task.text}`;
+}
+
+function formatThemedTask(task: Task, theme: Theme): string {
+  const marker = {
+    pending: theme.fg("dim", "○"),
+    in_progress: theme.fg("accent", "●"),
+    completed: theme.fg("success", "✓"),
+  }[task.status];
+  const text = task.status === "pending" ? theme.fg("muted", task.text) : theme.fg("text", task.text);
+
+  return `${marker} ${text}`;
+}
+
+export default function (pi: ExtensionAPI) {
+  let tasks: Task[] = [];
+
+  const refreshTaskUI = (ctx: ExtensionContext) => {
+    if (!ctx.hasUI) return;
+
+    const completed = tasks.filter((task) => task.status === "completed").length;
+    const remaining = tasks.filter((task) => task.status !== "completed");
+
+    if (remaining.length === 0) {
+      ctx.ui.setWidget("pi-task", undefined);
+      ctx.ui.setStatus("pi-task", undefined);
+      return;
+    }
+
+    ctx.ui.setStatus(
+      "pi-task",
+      ctx.ui.theme.fg("accent", `● Tasks ${completed}/${tasks.length}`),
+    );
+    ctx.ui.setWidget("pi-task", (_tui, theme) => {
+      const visible = remaining.slice(0, 7);
+      const lines = [
+        `${theme.fg("accent", theme.bold("Tasks"))} ${theme.fg("muted", `${completed}/${tasks.length}`)}`,
+        ...visible.map((task) => formatThemedTask(task, theme)),
+      ];
+      const hidden = remaining.length - visible.length;
+      if (hidden > 0) lines.push(theme.fg("dim", `… ${hidden} more`));
+
+      return new Text(lines.join("\n"), 0, 0);
+    });
+  };
+
+  const reconstructState = (ctx: ExtensionContext) => {
+    tasks = [];
+
+    for (const entry of ctx.sessionManager.getBranch()) {
+      if (entry.type !== "message") continue;
+      const message = entry.message;
+      if (message.role !== "toolResult" || message.toolName !== "task") continue;
+
+      const saved = message.details as TaskDetails | undefined;
+      if (saved && Array.isArray(saved.tasks)) tasks = cloneTasks(saved.tasks);
+    }
+
+    refreshTaskUI(ctx);
+  };
+
+  pi.on("session_start", async (_event, ctx) => reconstructState(ctx));
+  pi.on("session_tree", async (_event, ctx) => reconstructState(ctx));
+
+  pi.registerTool({
+    name: "task",
+    label: "Task",
+    description:
+      "Read or replace the complete ordered task list. Submit the full list to add, update, reorder, remove, or clear tasks. At most one task may be in_progress.",
+    promptSnippet: "Maintain an ordered task list for multi-step work",
+    promptGuidelines: [
+      "Use task for work with multiple meaningful steps; skip it for simple one-step requests.",
+      "Keep task items short and outcome-oriented, and submit the complete ordered list whenever it changes.",
+      "Keep exactly one task in_progress while actively working, and complete all tasks before finishing.",
+    ],
+    parameters: TaskParams,
+
+    async execute(_toolCallId, params, _signal, _onUpdate, ctx) {
+      const wasComplete = tasks.length > 0 && tasks.every((task) => task.status === "completed");
+
+      if (params.tasks !== undefined) {
+        const normalized = params.tasks.map((task) => ({
+          text: task.text.trim(),
+          status: task.status,
+        }));
+
+        if (normalized.some((task) => task.text.length === 0)) {
+          throw new Error("Task text cannot be empty");
+        }
+
+        const active = normalized.filter((task) => task.status === "in_progress").length;
+        if (active > 1) {
+          throw new Error("Only one task may be in_progress");
+        }
+
+        tasks = normalized;
+      }
+
+      const isComplete = tasks.length > 0 && tasks.every((task) => task.status === "completed");
+      refreshTaskUI(ctx);
+      if (ctx.hasUI && isComplete && !wasComplete) {
+        ctx.ui.notify(`✓ All ${tasks.length} tasks completed`, "info");
+      }
+
+      return {
+        content: [
+          {
+            type: "text",
+            text: tasks.length > 0 ? tasks.map(formatTask).join("\n") : "No tasks",
+          },
+        ],
+        details: { tasks: cloneTasks(tasks) } satisfies TaskDetails,
+      };
+    },
+  });
+
+  pi.registerCommand("tasks", {
+    description: "Refresh and show the current task list",
+    handler: async (_args, ctx) => {
+      refreshTaskUI(ctx);
+      if (ctx.hasUI) {
+        const remaining = tasks.filter((task) => task.status !== "completed").length;
+        const message =
+          tasks.length === 0
+            ? "No tasks"
+            : remaining === 0
+              ? `✓ All ${tasks.length} tasks completed; task UI is hidden`
+              : `${remaining} task(s) remaining; task UI refreshed`;
+        ctx.ui.notify(message, "info");
+      }
+    },
+  });
+}