Plan Elixir/Phoenix Feature

Plan a feature by spawning Elixir specialist agents, then output structured plan with checkboxes.

What Makes /phx:plan Different from /plan

1. Spawns Elixir specialist agents for research
2. Plans with [ecto], [liveview], [oban] task routing
3. Checks for Iron Law compliance in the plan
4. Includes mix compile/format/credo/test verification
5. Understands Phoenix context boundaries

Usage

/phx:plan Add user avatars with S3 upload
/phx:plan .claude/plans/notifications/reviews/notifications-review.md
/phx:plan Implement notifications --depth deep
/phx:plan .claude/plans/auth/plan.md --existing

Arguments

• $ARGUMENTS = Feature description, review file, or existing plan
• --depth quick|standard|deep = Planning depth (auto-detected)
• --existing = Enhance an existing plan with deeper research

Workflow

1. Gather context — File path (skip to agents), brainstorm interview.md (skip clarification), clear description, or vague
2. Clarify if vague — Ask questions ONE at a time (skip if brainstorm interview.md exists with Status: COMPLETE)
3. Detect depth — Auto-detect quick/standard/deep
4. Runtime context (Tidewave) — Gather live schemas, routes, and warnings before spawning agents (direct path only — the research orchestrator gathers its own)
5. Spawn research — Selective, based on need. 0–2 agents: spawn directly in parallel. 3+ agents (broad multi-context feature): determine the effective maximum nesting depth. Use an explicit positive-integer CLAUDE_CODE_MAX_SUBAGENT_SPAWN_DEPTH value first; when it is unset, inspect claude --version (the default is 1 in 2.1.217–2.1.218 and 3 in 2.1.219+). If the version is unavailable, conservatively use 1. At depth 3+, spawn ONE planning-orchestrator to run and compress the fan-out. At depth 1 or 2, keep orchestration in this main session: spawn the selected specialist agents directly, wait for them, then spawn phx:context-supervisor directly if compression is needed. Never spawn an orchestrator that cannot delegate. Read only the resulting digest and summaries/consolidated.md. If TaskCreate is in your tool list (never ToolSearch for it), create a task per spawn: TaskCreate({subject: "{Agent} research", activeForm: "Researching..."}), mark in_progress on spawn, completed when done
6. Wait for ALL agents — Do NOT proceed until all return "completed". NEVER write plan while any agent is still running
7. Breadboard (LiveView) — System map for multi-page features
8. Completeness check — required when planning from review
9. Split decision — One plan or multiple, concrete options
10. Generate plan — Checkboxes, phased tasks, code patterns. Also create plans/{slug}/scratchpad.md for decisions and dead-ends
11. Self-check (deep only) — Three questions in Risks section
12. Present and ask — STOP, show summary, let user decide

When planning from review: Every finding must appear in the plan — either as a task OR explicitly deferred by the user.

See ${CLAUDE_SKILL_DIR}/references/planning-workflow.md for detailed step-by-step.

--existing Mode (Deepening)

Enhances an existing plan instead of creating a new one:

1. Load plan, search .claude/solutions/ for known risks
2. Spawn SPECIALIST agents (not Explore) for thin sections. Each agent writes to .claude/plans/{slug}/research/ and returns only a 500-word summary. Same agent selection rules
3. Wait for ALL agents (mark tasks completed as each finishes)
4. Add implementation detail, resolve spikes, add verification
5. Present diff summary — NEVER delete existing tasks

Iron Laws

1. NEVER auto-start /phx:work — Always present plan and ask
2. Research before assuming — Web-search unfamiliar tech
3. Spawn agents selectively — Only relevant, not all
4. NEVER write plan while agents still running
5. NEVER skip input findings — Every finding MUST have a task
6. Do NOT spawn hex-library-researcher for existing deps
7. Skip research when planning from review/investigation — When input is a review file or /phx:investigate output, the findings ARE the research. Do NOT spawn agents to re-discover what the review already found. Convert findings directly to plan tasks. (Confirmed: 56-session analysis showed same findings discovered 3-4x across review→investigate→plan phases, wasting ~96K tokens)

Integration with Workflow

/phx:plan {feature}  <-- YOU ARE HERE
       |
   /phx:plan --existing (optional enhancement)
       |
   ASK USER -> /phx:work .claude/plans/{feature}/plan.md
       |
/phx:review → /phx:compound

Notes

• Plans saved to .claude/plans/{slug}/plan.md
• Research reports in .claude/plans/{slug}/research/ can be deleted after

CRITICAL: After Writing the Plan

STOP. Do NOT proceed to implementation.

After writing .claude/plans/{slug}/plan.md:

1. Summarize: task count, phases, key decisions
2. Use AskUserQuestion with options:
   • "Start in fresh session" (recommended for 5+ tasks)
   • "Get a briefing" (/phx:brief — interactive walkthrough)
   • "Start here"
   • "Review or adjust the plan"
3. Wait for user response. Never auto-start work.

When user selects "Start in fresh session", print:

1. Run `/new` to start a fresh session
2. Then run one of:
   /phx:work .claude/plans/{slug}/plan.md
   /phx:full .claude/plans/{slug}/plan.md  (includes review + compound)

This is Iron Law #1. Violating it wastes user context.

References (DO NOT read — for human reference only)

• ${CLAUDE_SKILL_DIR}/references/planning-workflow.md — Detailed step-by-step
• ${CLAUDE_SKILL_DIR}/references/plan-template.md
• ${CLAUDE_SKILL_DIR}/references/complexity-detail.md
• ${CLAUDE_SKILL_DIR}/references/example-plan.md
• ${CLAUDE_SKILL_DIR}/references/agent-selection.md
• ${CLAUDE_SKILL_DIR}/references/breadboarding.md