Plan Architecture

"Architecture is the art of making decisions you will not regret when the plugin grows."

Generate a complete architecture plan for a Claude Code plugin. Takes a plugin concept brief (from ideate-plugin) and produces a detailed technical plan covering agents, skills, hooks, commands, quality gates, and execution flows.

Procedure

Step 1 -- Parse Plugin Brief

• Read the plugin brief document at the provided path.
• Extract: problem statement, movement structure, component estimates, feasibility notes.
• If no brief exists at the path, report the error and suggest running /pqa:ideate first.
• Validate that the brief has the required sections. Tag findings: [DOC].

Step 2 -- Determine Agent Roles

• For each movement, decide whether it needs a dedicated agent or shares the plugin's primary agent.
• Apply the heuristic: a movement gets its own agent if it has 5+ skills OR fundamentally different tool needs.
• For each agent, define:
  • Name: kebab-case, role-descriptive (e.g., code-analyzer, report-generator).
  • Boundary: What it owns and what it delegates.
  • Tool allowlist: Minimum tools needed (least privilege).
  • maxTurns: Estimated based on skill count and complexity.
• Record the plugin subagent constraint: no hooks, mcpServers, or permissionMode in agent frontmatter. [CONFIG]

Step 3 -- Map Skills to Movements

• For each movement from the brief, list the skills with:
  • Name: kebab-case verb-noun (e.g., validate-structure, generate-report).
  • Purpose: One sentence.
  • Inputs: What data/files it reads.
  • Outputs: What it produces (findings, artifacts, reports).
  • Agent: Which agent orchestrates it.
  • Sequence: Order within the movement (parallel or sequential).
• Verify no skill appears in multiple movements. [DOC]

Step 4 -- Select Hooks from Compatibility Matrix

• Review the 22 lifecycle events available in Claude Code.
• For each proposed hook from the brief, validate against the type-event compatibility matrix:
  • type:command -- compatible with all 22 events.
  • type:http -- compatible with all 22 events.
  • type:prompt -- compatible with PreToolUse, PostToolUse, and PermissionRequest ONLY (requires ToolUseContext).
  • type:agent -- compatible with PreToolUse, PostToolUse, and PermissionRequest ONLY (requires ToolUseContext).
• Flag any incompatible combinations as CRITICAL (prompt/agent on non-ToolUseContext events) and propose alternatives.
• Document the hook strategy: which events, which types, what behavior. [CONFIG]

Step 5 -- Define Command Routing

• For each user-facing operation, create a command entry:
  • Canonical command: Full descriptive name (e.g., /prefix:validate).
  • Alias: Optional single-letter shortcut (e.g., /prefix:v).
  • Target: Which skill or agent the command invokes.
  • Arguments: What the command passes through.
• Verify no command name conflicts with existing commands in the plugin ecosystem.
• Total commands = canonical + aliases. Document the count. [DOC]

Step 6 -- Place Quality Gates

• Define quality gates between movements:
  • Gate name: Descriptive (e.g., G1: Analysis Complete).
  • Trigger: What must be true to pass (e.g., "all validate-* skills pass with zero CRITICALs").
  • Blocker behavior: What happens if the gate fails (pause, skip, abort).
• Minimum: one gate between each movement boundary.
• Gate criteria must be testable and evidence-based. [DOC]

Step 7 -- Generate Architecture Diagrams

• Produce Mermaid diagrams for:
  1. Component map: Agents, skills, commands, hooks and their relationships.
  2. Execution flow: Sequential/parallel skill execution within each movement.
  3. Delegation graph: Agent-to-skill ownership.
• Diagrams must be valid Mermaid syntax. [CODIGO]

Step 8 -- Write Architecture Plan

• Compile all outputs into architecture-plan.md:

  # Architecture Plan: {plugin-name}
  ## Overview
  ## Agent Roles
  ## Skill-Movement Map
  ## Hook Strategy
  ## Command Routing Table
  ## Quality Gates
  ## Diagrams
  ## Component Summary
  ## Next Steps

• Include a component summary table: total agents, skills, commands, hooks.
• Present the plan for review. Suggest running /pqa:plan-moat next.
• Write the file only if the user confirms. [DOC]

Quality Criteria

• Every skill has exactly one owning agent -- no orphaned skills. [CODIGO]
• Every hook type-event combination is compatible per the matrix. [CONFIG]
• Command names are unique and follow kebab-case conventions. [CODIGO]
• Quality gates have testable, measurable criteria. [DOC]
• Mermaid diagrams render correctly (valid syntax). [CODIGO]
• The plan accounts for all components estimated in the brief. [DOC]
• Plugin subagent constraints are documented prominently. [CONFIG]

Assumptions & Limits

• This skill produces a plan document, not code. It does not create directories, files, or scaffolds -- that is build-plugin-scaffold's job.
• The hook compatibility matrix is taken as authoritative. If the official Claude Code spec changes, this skill's Step 4 must be updated to match.
• Agent count heuristic (5+ skills = dedicated agent) is a guideline, not a rule. Simple plugins may work fine with a single agent regardless of skill count.
• Cannot validate that the proposed architecture is optimal -- only that it is internally consistent and spec-compliant.
• Mermaid diagram generation assumes the user's rendering environment supports Mermaid syntax. No fallback for environments that do not.

Good vs Bad

Bad architecture plan excerpt:

## Agents
- Agent 1: handles stuff
- Agent 2: handles other stuff

Missing: no tool allowlist, no boundaries, no maxTurns, no skill assignments.

Good architecture plan excerpt:

## Agent Roles
| Agent | Boundary | Skills Owned | Tools | maxTurns |
|-------|----------|-------------|-------|----------|
| code-analyzer | Owns validation movement. Reads only. | validate-structure, validate-manifest, validate-components | Read, Glob, Grep | 25 |
| report-generator | Owns reporting movement. Writes report files. | generate-qa-report, generate-qa-scorecard | Read, Glob, Write | 15 |

Includes: agent name, boundary, skills owned, tool allowlist, maxTurns estimate.

Anti-Patterns

1. Creating one agent per skill -- agents should manage groups of related skills.
2. Using type:prompt hooks on Stop or Compact events (runtime error).
3. Defining quality gates without measurable criteria ("it looks good" is not a gate).
4. Creating aliases for commands that are rarely used (aliases are for frequent operations).
5. Putting all skills in a single movement (defeats the purpose of movement-based organization).

Edge Cases

1. Plugin with a single movement -- valid for simple plugins. Skip quality gates between movements but add an exit gate.
2. Plugin with no hooks -- valid. Many plugins operate entirely on-demand. Document the decision.
3. Brief proposes more than 4 agents -- review whether some can be merged. More than 4 agents is a code smell for plugins.
4. A skill needs Write access but the movement is labeled "read-only" -- resolve the contradiction before proceeding.