[fix] Normalize legacy persisted tasks

[arrokh]

Issue Details

Pi could exit from an uncaught exception while rendering the task widget:

TypeError: Cannot read properties of undefined (reading length)
at TaskWidget.renderWidget (.../src/ui/task-widget.ts:188:55)

The failing path was a persisted legacy task record that did not include newer task fields such as blockedBy, blocks, or metadata. TaskWidget and other consumers expect TaskStore to return fully-shaped Task objects, so reading task.blockedBy.length could throw before the UI could recover.

Purpose

Normalize legacy persisted task data at the TaskStore load boundary so every consumer receives canonical task objects. This preserves existing widget/tool behavior while making old task files compatible with the current task schema.

Summary

• Added load-time normalization for file-backed tasks in TaskStore.
• Default missing metadata to {} and missing dependency arrays to [].
• Preserve existing timestamps and nextId behavior for persisted task files.
• Added regression coverage at both the store boundary and widget render path.

Issue → Solution Flow

flowchart TD
    A[Legacy persisted task file] --> B[TaskStore.load]
    B --> C{Missing newer fields?\nblockedBy / blocks / metadata}
    C -->|Before| D[Raw partial task returned]
    D --> E[TaskWidget.renderWidget]
    E --> F[task.blockedBy.length]
    F --> G[Uncaught TypeError\npi exits]

    C -->|After| H[normalizeTask fills defaults]
    H --> I[Canonical Task object]
    I --> J[Widget and tools read arrays safely]
    J --> K[Task list renders without throwing]

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Validation

• Reproduced the failing widget regression before the fix.
• npm test -- --run test/task-store.test.ts test/task-widget.test.ts — 80 tests passed.
• npm run typecheck — passed.
• npm run lint — passed.
• npm run build — passed.
• npm run prepublishOnly — passed (lint, typecheck, test, build; 170 tests).
• Node smoke check confirmed a legacy task is normalized and rendered by the widget without throwing.
• Confirmed installed package source/dist copy matches the TaskStore fix for immediate local use.