Agent Command Authoring

Agent Command Authoring

Create commands for Claude Code, OpenCode, and Pi that are thin wrappers around reusable agent capabilities.

When to Use This Skill

Use this skill when:

• Creating a new custom command
• Refactoring an existing command to delegate correctly
• Porting commands between Claude Code, OpenCode, and Pi
• Ensuring consistency between command implementations across agent harnesses

Platform Model

Different harnesses support different delegation mechanisms:

Pi does not have subagents by default, so Pi command templates should not reference Task(...), agent:, or "use the <name> subagent". Convert those to direct skill invocation.

The Delegation Pattern

For Claude Code and OpenCode, commands should usually be thin wrappers that delegate to subagents, which in turn delegate to skills:

command → subagent → skill

For Pi, commands are prompt templates and should invoke skills directly:

prompt template → skill

Claude Code Command Structure

Claude Code command (.claude/commands/<name>.md):

---
description: Brief description of what the command does
allowed-tools: Task(subagent-name)
---

Use the `<subagent-name>` subagent to accomplish this task.

Frontmatter Fields

allowed-tools Format

For commands that delegate to subagents:

• Task(subagent-name) - Invoke a subagent

For commands that must run in the current session context:

• Skill(skill-name) - Invoke the skill directly

Example:

allowed-tools: Task(git-committer)

OpenCode Command Structure

OpenCode command (.config/opencode/command/<name>.md):

---
description: Brief description of what the command does
agent: <subagent-name>
---

Use the `<subagent-name>` subagent to accomplish this task.

Frontmatter Fields

For session-context-dependent commands, omit agent: so the command runs in the primary agent's context, and invoke the skill directly in the body.

Pi Prompt Template Structure

Pi prompt template (.pi/prompts/<name>.md or ~/.pi/agent/prompts/<name>.md):

---
description: Brief description of what the command does
argument-hint: "[optional-args]"
---

Use the `<skill-name>` skill to accomplish this task.

Arguments: $ARGUMENTS

Frontmatter Fields

Pi Rules

• Filename becomes the slash command: .pi/prompts/review.md creates /review.
• Use $1, $2, $@, or $ARGUMENTS for arguments.
• Do not include Claude/OpenCode-only fields: allowed-tools, agent, model, mode, permission, or tools.
• Do not reference subagents unless a Pi extension/package explicitly provides them. Prefer direct skill invocation.
• After adding or changing templates in a running Pi session, run /reload.

Common Subagent → Skill Mapping for Pi

When porting existing Claude/OpenCode commands to Pi, map common subagents to skills:

Naming Conventions

Command names should use the imperative form of verbs (telling the agent what to do):

• ✅ commit, stage, lint, test, review, reflect
• ❌ committing, git-committer, do-linting

The imperative form gives commands their characteristic feel:

• "commit" = "perform a commit"
• "stage" = "stage changes"
• "test" = "run tests"

Command Body

The command body should be 5-20 lines maximum and contain only delegation and argument-passing instructions.

Claude/OpenCode subagent command:

Use the `<subagent-name>` subagent to accomplish this task.

Pi prompt template or direct-skill command:

Use the `<skill-name>` skill to accomplish this task.

Arguments: $ARGUMENTS

Do NOT include:

• Full implementation steps
• Duplicated content between command wrappers
• More than ~20 lines of content
• Platform-specific frontmatter in the wrong platform's command file

Examples

Minimal Command (Claude Code)

---
description: Create well-formatted commits using conventional commits style
allowed-tools: Task(git-committer)
---

Use the `git-committer` subagent to create a well-formatted commit.

Minimal Command (OpenCode)

---
description: Create well-formatted commits using conventional commits style
agent: git-committer
---

Use the `git-committer` subagent to create a well-formatted commit.

Minimal Command (Pi)

---
description: Create well-formatted commits using conventional commits style
---

Use the `git-commit` skill to create a well-formatted commit.

Command with Arguments (Claude Code)

---
description: Generate a PRP
argument-hint: [feature_name]
allowed-tools: Task(prp-generator)
---

Use the `prp-generator` subagent to create a Product Requirements Prompt.

Command with Arguments (Pi)

---
description: Generate a PRP
argument-hint: "[feature_name]"
---

Use the `prp-generation` skill to create a Product Requirements Prompt.

Feature: $ARGUMENTS

Why This Pattern?

1. Single source of truth: Skills contain all implementation content
2. Easier maintenance: Changes to skills automatically propagate
3. Platform consistency: Commands are thin wrappers with platform-specific frontmatter
4. Token efficiency: Skills load progressively via progressive disclosure
5. No duplication: Implementation lives in one place (the skill)
6. Isolation where available: Claude/OpenCode subagents run context-independent tasks in their own context
7. Pi compatibility: Pi prompt templates preserve slash-command ergonomics without assuming subagents

Anti-Pattern to Avoid

BAD - Command with full implementation:

---
description: Stage changes
allowed-tools: Bash(git add:*)
---

# Staging Changes

Stage relevant changes via `git add`...

1. Run `git status` to check for already staged changes
2. Verify no staged changes exist...
3. Run `git status` again...
4. Carefully review which files are relevant...
5. Stage only the relevant files...
6. Run `git status` again...

BAD for Pi - Pi template that references a subagent:

---
description: Stage changes via git add
---

Use the `git-stager` subagent to stage relevant changes.

GOOD for Pi - Pi template that invokes the skill directly:

---
description: Stage changes via git add
---

Use the `git-staging` skill to stage relevant changes.

BAD for Claude/OpenCode - Command that delegates directly to skill for a context-independent task when a subagent exists:

---
description: Stage changes via git add
allowed-tools: Skill(git-staging)
---

Use the `git-staging` skill to stage relevant changes.

GOOD for Claude/OpenCode - Command that delegates to subagent for a context-independent task:

---
description: Stage changes via git add
allowed-tools: Task(git-stager)
---

Use the `git-stager` subagent to stage relevant changes.

EXCEPTION - Commands that are inherently session-context-dependent (e.g. "review what I just wrote", "remove duplication I just introduced") should skip the subagent and invoke the skill directly. Subagents start with a fresh context and will not know what was recently worked on unless the parent agent tells them — which defeats the purpose of the command.

---
description: Remove code duplication you just introduced
allowed-tools: Skill(code-refactoring-dry)
---

Use the `code-refactoring-dry` skill to remove duplication in the files you
have worked on in this session.

In OpenCode, omit the agent: field entirely for the same effect. In Pi, all prompt templates should use this direct skill-invocation style.

Workflow

1. Check for existing skill: Identify the skill the command should use.
2. For Claude/OpenCode context-independent commands: Check for an existing subagent that delegates to that skill:
   • Claude Code: .claude/agents/<name>.md
   • OpenCode: .config/opencode/agents/<name>.md
3. If no subagent exists for Claude/OpenCode: Ask the user if they want one created.
   • If yes, use the subagent-authoring skill to create it first.
   • If no, create only the Pi template or stop and explain the limitation.
4. Create/refactor Claude Code command with allowed-tools: Task(subagent-name).
5. Create/refactor OpenCode command with agent: subagent-name.
6. Create/refactor Pi prompt template with direct skill invocation in .pi/prompts/<name>.md.
7. Verify the chains:
   • Claude/OpenCode: command → subagent → skill
   • Pi: prompt template → skill

Missing Subagent Handling

Before creating a Claude/OpenCode subagent command, always verify the target subagent exists:

# Check Claude Code subagent
ls ~/.claude/agents/<subagent-name>.md

# Check OpenCode subagent
ls ~/.config/opencode/agents/<subagent-name>.md

If either file is missing, ask the user:

"The subagent <subagent-name> doesn't exist yet. Would you like me to create it using the subagent-authoring skill before proceeding with the Claude/OpenCode command?"

Do NOT create Claude/OpenCode commands that reference non-existent subagents. This requirement does not apply to Pi prompt templates, which should reference skills directly.

Verification

After creating or refactoring commands:

# YAML/frontmatter sanity check for generated markdown files
python3 - <<'PY'
from pathlib import Path
import yaml
for root in ['.claude/commands', '.config/opencode/command', '.pi/prompts']:
    for path in Path(root).glob('*.md'):
        text = path.read_text()
        if text.startswith('---\n'):
            yaml.safe_load(text.split('---', 2)[1])
print('command frontmatter ok')
PY

For Pi, also check that templates do not contain Claude/OpenCode-only fields:

grep -RIn 'allowed-tools\|^agent:\|Task(\|subagent' .pi/prompts || true

Run /reload in active Pi sessions after changing Pi prompt templates.

Related Skills

• subagent-authoring - For creating Claude/OpenCode subagent definitions that delegate to skills
• skill-authoring - For creating skills themselves