Decouple task workflow from cbox CLI — add /cbox-task command surface

Problem

CBox is a generic sandbox/review agent manager. Task-driven execution (tasks tasks) was previously only available through the monolithic master-plan-cbox-manager skill. This task extracts the "execute one task" contract into a focused, invocable /cbox-task command and shared skill, keeping cbox CLI itself task-unaware.

Context

Possible Solutions

Plan

Implementation Progress

• Add /cbox-task Claude Code command (.claude/commands/cbox-task.md) with contract for task path + execution constraints.
• Add shared cbox-task skill (libs/cbox/skills/cbox-task/SKILL.md) for cross-environment reuse.
• Document design rationale and usage examples in canonical docs (docs/agent/cbox.md).
• Update skill index, agent docs, and Cursor/Codex wrappers to reference the new skill.

• Update this task file with implementation notes and tradeoffs.

• /cbox-task <task-path> is a valid Claude Code command that agents can invoke.

• Shared skill is registered in libs/cbox/skills/INDEX.md.
• CBox CLI (libs/cbox/cbox/cli.py) is NOT modified — zero task coupling.
• Canonical docs explain the task-driven workflow and design rationale.
• All touched files pass lint.

Design Decisions

Skill-first over CLI flag

Chosen: Skills/commands that compose existing cbox primitives. Rejected: Adding --task flag to cbox new or cbox send.

Rationale: - CBox stays generic — usable for reviews, sandboxes, ad-hoc work without task coupling. - Teams not using tasks get no extra flags or dependencies. - Composition over configuration — /cbox-task composes cbox new + cbox send + plans_cli.py rather than adding task-specific flags to cbox. - If a CLI flag is needed later, it can be added as a thin passthrough without breaking the skill contract.

Single-task vs multi-task scope

/cbox-task: single-task execution — read task, launch sandbox, delegate, complete. master-plan-cbox-manager: multi-task triage, execution queues, batch workflows.

The two are complementary. /cbox-task can be used inside the manager loop or standalone.

Files created: - .claude/commands/cbox-task.md — Claude Code /cbox-task command - libs/cbox/skills/cbox-task/SKILL.md — shared canonical skill

Files modified: - docs/agent/cbox.md — added "Task-Driven Workflow (Optional)" section with rationale - libs/cbox/skills/INDEX.md — registered cbox-task skill - libs/cbox/CLAUDE.md — added reference to new skill - .cursor/rules/cbox.mdc — added /cbox-task reference - .codex/skills/cbox/SKILL.md — added task-driven execution section - tasks/workstreams/infra-tooling/tasks/cbox-decoupled-task-workflow-command-surface.md — this file

Files NOT modified (by design): - libs/cbox/cbox/cli.py — cbox CLI stays task-unaware - libs/cbox/cbox/tmux.py — no changes needed - libs/cbox/cbox/container.py — no changes needed

Open Risks

• The prompt template in /cbox-task is static text. If task file format changes significantly, the prompt composition may need updating.

• Incident logging reuses master-plan-cbox-manager/scripts/log_issue.sh — if the manager skill moves or restructures, the path reference breaks. Could be mitigated by promoting log_issue.sh to a shared location.

• Related skill: libs/cbox/skills/master-plan-cbox-manager/SKILL.md

Review Feedback

• [ ] Review cleared