feat: Task history + sub-tasks — persistence, hierarchy, scope inheritance

[Abernaughty]

Summary

Implement persistent task history with summary details for completed tasks, and sub-task creation with scope/context inheritance. Enables the key workflow: PR review feedback → create sub-task to address it.

Context

Per the Dashboard Workflow Roadmap, Section 8. Currently, task state is ephemeral — when a task completes, its data is only in memory/SSE. This adds persistence and hierarchy.

Design

Task History

Persistent record for each completed task:

• Task ID, objective, workspace, status, duration, cost
• Blueprint summary and acceptance criteria results
• Output artifacts: files created, PRs opened, commands executed
• Clickable for full detail view (same as click-to-expand in feat: Agent dashboard click-to-expand — task detail view + output redaction #108)

Sub-Task Creation

Sub-tasks can be created from completed tasks, inheriting context:

• Scope inheritance: Same workspace or narrower. Cannot widen scope beyond parent's workspace unless wider scope is in approved directories list.
• Context inheritance: Sub-task Architect receives parent task's blueprint + QA verdict + files as L1 memory context.
• PR review → sub-task: Natural workflow for addressing PR feedback — create sub-task from PR review, inherit parent task scope, Architect sees review comments.

Data Model

class TaskRecord(TypedDict):
    task_id: str
    parent_task_id: str | None   # Enables hierarchy
    objective: str
    workspace: str
    status: str                  # completed, failed, escalated
    duration_seconds: float
    total_cost: float
    blueprint_summary: dict
    acceptance_results: list[dict]
    output_artifacts: list[dict]  # files, PRs, commands
    created_at: str
    completed_at: str

Sub-tasks appear nested under parent in task history view.

Storage

• Phase 2: Local JSON or SQLite
• Phase 3: Migrate to persistent database alongside pgvector

Acceptance Criteria

• Task history persistence (all completed tasks saved)
• Task history UI in dashboard — list view with summary cards
• Click-to-expand detail view for each historical task
• parent_task_id field on task model
• Sub-task creation flow: "Create sub-task" button on completed tasks
• Scope inheritance enforcement (same or narrower workspace)
• Context inheritance: parent blueprint + QA verdict passed to sub-task Architect as L1 memory
• PR review → sub-task creation workflow
• Nested display of sub-tasks under parent in history
• Search/filter task history by workspace, status, date

Dependencies

• feat: Planner agent + Chat task creation — readiness checklist, workspace selector, TaskSpec #106 (Planner agent + Chat task creation) — sub-tasks flow through the same task creation pipeline

Effort

Large (2-3 sessions)

Source

Dashboard Workflow Roadmap, Section 8 — Task History & Sub-Tasks