extend

name	extend
description	Use when creating new skills, specialists, agents, or packs for the Jig framework. Guides the user through an interview to determine what to build, scaffolds the artifact with valid frontmatter, checks for overlap with existing artifacts, and verifies it loads correctly. Triggered by "create a skill", "add a specialist", "extend the framework", or /extend.
tier	workflow
alwaysApply	false

Framework Extension Assistant

PURPOSE: The meta-skill. Teaches teams to build on Jig by guiding artifact creation from intent through scaffolding to verification. Every new skill, specialist, agent, pack, or config change goes through this skill to ensure it follows the schema, avoids overlap, and loads correctly.

CONFIGURATION: Reads jig.config.md for the Concerns Checklist (to wire new artifacts into) and existing artifact inventory.

---

When to Use

• "I want to create a new skill"
• "We need a specialist for X"
• "How do I add a review check for Y?"
• "Let's capture our team's conventions"
• "I want to automate Z in the pipeline"
• /extend invoked directly
• postmortem identifies the need for an entirely new artifact

Do NOT use when:

• Modifying an existing skill (edit it directly)
• The change is just a config value in jig.config.md (edit the config directly)
• You need to run a pipeline step (use the appropriate pipeline skill)

---

Step 1: Interview

Understand what the user is trying to capture before deciding what to build.

Ask these questions one at a time:

1. What are you trying to capture? (a rule, domain knowledge, a workflow step, a review check, an automation)
2. What problem does it solve? (what goes wrong without this? what mistake does it prevent?)
3. When should it activate? (always? when editing certain files? only when invoked?)
4. Do you have an example? (a recent PR comment, a bug, a pattern you keep explaining)

These questions drive the decision tree below. Do not ask all four if the first two make the answer obvious.

---

Step 2: Determine Artifact Type

Based on the interview, route to the correct artifact type:

"I want to enforce a rule"
  +-- Universal rule (every file) --> Standards-tier skill
  +-- Rule for specific code areas --> Domain-tier or feature-tier skill
  +-- Rule checked during review --> Specialist

"I want to capture domain knowledge"
  +-- Patterns for a code area --> Domain-tier skill
  +-- Patterns for one feature --> Feature-tier skill

"I want to add a workflow step"
  +-- New pipeline stage or orchestration --> Workflow-tier skill
  +-- Modification to existing stage --> Edit the existing skill

"I want to review code for X"
  +-- Pattern-based check (scannable) --> Specialist
  +-- Reasoning-based check (requires tracing) --> Logic reviewer pattern

"I want to automate a task"
  +-- Triggered by user command --> Agent
  +-- Triggered by file edits --> Domain-tier skill

"I just need to change pipeline behavior"
  +-- Stage overrides, thresholds, models --> jig.config.md change (no new artifact)
  +-- New concern in PRD authoring --> Add to Concerns Checklist in jig.config.md

Decision Matrix

Intent	Artifact	Location	Schema Reference
Universal rule	Standards-tier skill	team/skills/{name}/SKILL.md	framework/SKILL_SCHEMA.md
Domain patterns	Domain-tier skill	team/skills/{name}/SKILL.md	framework/SKILL_SCHEMA.md
Feature patterns	Feature-tier skill	team/skills/{name}/SKILL.md	framework/SKILL_SCHEMA.md
Pipeline step	Workflow-tier skill	team/skills/{name}/SKILL.md	framework/SKILL_SCHEMA.md
Review check (pattern)	Specialist	team/specialists/{name}.md	framework/SKILL_SCHEMA.md (Specialist Schema section)
Review check (reasoning)	Logic reviewer pattern	core/skills/review/logic-reviewer.md	Edit existing file
Automation	Agent	team/agents/{name}.md	Agent conventions
Pipeline config	Config change	jig.config.md	Edit existing file
Brainstorm concern	Concerns checklist entry	jig.config.md	framework/CONCERNS_CHECKLIST.md

---

Step 3: Check for Overlap

Before creating anything, search for existing artifacts that might already cover this.

1. Search skills: Scan team/skills/, packs/*/skills/, and core/skills/ for skills with related names, descriptions, or globs
2. Search specialists: Scan team/specialists/, packs/*/specialists/, and core/specialists/ for specialists covering the same concern
3. Search agents: Scan team/agents/, packs/*/agents/, and core/agents/
4. Read candidates: For each potential overlap, read the file and check if the pattern is already documented

If overlap is found:

Situation	Action
Pattern already covered, well documented	No new artifact needed. Tell the user.
Pattern partially covered	Extend the existing artifact instead of creating a new one
Related but distinct concern	Proceed with new artifact, note the relationship
Same domain, different scope	Proceed, but ensure globs do not overlap excessively

---

Step 4: Scaffold the Artifact

For Skills

Create team/skills/{name}/SKILL.md with valid frontmatter:

---
name: {name}
description: >
  Use when {specific trigger condition}. {What it helps with}.
tier: {standards | domain | feature | workflow}
globs:                          # Only for domain and feature tiers
  - "{glob-pattern}"
alwaysApply: {true | false}     # true only for standards tier
---

Scaffold the body:

# {Skill Title}

**PURPOSE**: {One sentence describing what this skill does.}

**CONFIGURATION**: {What it reads from jig.config.md, if anything.}

---

## When to Use

- {Trigger condition 1}
- {Trigger condition 2}

**Do NOT use when:** {Exclusion conditions}

---

## ALWAYS

- {Non-negotiable rule 1}
- {Non-negotiable rule 2}

## NEVER

- {Anti-pattern 1}
- {Anti-pattern 2}

## Patterns

### {Pattern Name}

{Description, examples, good/bad comparisons}

---

## Common Mistakes

| Mistake | Fix |
|---------|-----|
| {Common error} | {How to avoid it} |

---

## Integration

**Called by:** {Which skills invoke this one}

**Related skills:** {Related skills to cross-reference}

Tier selection guidance:

Tier	When	Globs	alwaysApply
Standards	Rule applies to EVERY file edit. Very rare -- think twice.	Not needed	true
Domain	Patterns for a code area (database, frontend, testing)	Scoped to directories: **/entities/**/*.ts	false
Feature	Patterns for one specific feature's code	Narrow paths: **/component-filter/**/*	false
Workflow	Pipeline step invoked explicitly	None	false

Glob guidance:

• Scope by code location, not applicability
• **/entities/**/*.ts (good) vs **/*.ts (too broad)
• Test the glob mentally: what files would this match? Are there false positives?

For Specialists

Create team/specialists/{name}.md with valid frontmatter:

---
name: {name}
description: Reviews {specific concern}
model: {haiku | sonnet | opus}
tier: {fast-pass | full-only}
globs:
  - "{glob-pattern}"
severity: {blocking | major | minor}
---

Scaffold the body (this IS the specialist's prompt):

## What to Check

- {Check 1: specific, actionable}
- {Check 2: specific, actionable}
- {Check 3: specific, actionable}

## What to Ignore

- {Exclusion 1: things that look like issues but are not}
- {Exclusion 2: out of scope for this specialist}

## Report Format

For each finding:
- **File**: path:line_number
- **Finding**: {description}
- **Fix**: {actionable suggestion}

If nothing found, respond with exactly: `N/A`

Model selection:

Model	When	Cost
haiku	Pattern matching, checklist verification, syntax checks	Lowest
sonnet	Moderate reasoning, context-dependent patterns	Medium
opus	Deep reasoning, cross-file analysis, subtle bugs	Highest

Tier selection:

Tier	When	Runs during
fast-pass	Critical checks that should block every task	Per-task review (team-dev) + pre-PR
full-only	Thorough checks that only need to run once	Pre-PR review only

Severity selection:

Severity	When	Impact on review score
blocking	Security vulnerabilities, data loss risks, broken contracts	Score capped at 4
major	Bugs, performance issues, pattern violations	Score capped at 7
minor	Style suggestions, minor improvements	Score 8-9

For Agents

Create team/agents/{name}.md:

# {Agent Name}

**Trigger**: {What phrase or command activates this agent}

**Purpose**: {What the agent does}

## Instructions

{The agent's prompt -- what it should do step by step}

## Tools Required

- {Tool 1}
- {Tool 2}

For Config Changes

Edit jig.config.md directly. Common changes:

• New concern: Add to ## Concerns Checklist with a skill/specialist reference
• Stage override: Add to work type overrides
• Threshold change: Update parallel-threshold, swarm-tiers, etc.
• New commit scope: Add to scopes list

---

Step 5: Wire into Concerns Checklist (if appropriate)

If the new artifact represents a concern that should be surfaced during PRD authoring:

1. Open jig.config.md
2. Add an entry to ## Concerns Checklist:

   - {concern-name}: team/skills/{skill-name}
   

   or for specialists:

   - {concern-name}: team/specialists/{specialist-name}
   

3. Confirm with the user: "Added {concern} to the Concerns Checklist. It will be surfaced during PRD authoring for features and improvements."

Not every artifact belongs in the checklist. Only add it if it represents a cross-cutting concern that should be explicitly considered during design.

---

Step 6: Verify

After creating the artifact, verify it will be discovered and loaded correctly:

1. Frontmatter validation:

   • name is present, unique, max 64 chars
   • description starts with "Use when..." (for skills) or "Reviews..." (for specialists)
   • tier is one of the valid values
   • globs are present for domain/feature tiers, absent for workflow/standards
   • alwaysApply is true only for standards tier

2. File location check:

   • Skill: team/skills/{name}/SKILL.md exists
   • Specialist: team/specialists/{name}.md exists
   • Agent: team/agents/{name}.md exists

3. Overlap recheck:

   • No other artifact in the discovery chain has the same name
   • If a core artifact has the same name, the team artifact will override it (confirm this is intentional)

4. Glob test (for domain/feature):

   • List a few files that should match the globs
   • List a few files that should NOT match
   • Confirm the globs are not too broad

5. Content quality:

   • SKILL.md is under 500 lines (heavy content belongs in reference/ subdirectory)
   • No placeholders (TBD, TODO) in the final artifact
   • Cross-references use the format: **REQUIRED**: Use {skill-name} for {reason}

Report the verification results to the user.

---

Reference Documents

These framework documents define the schemas and systems this skill works with:

Document	When to Reference
framework/SKILL_SCHEMA.md	Frontmatter fields, file structure, writing guidelines
framework/TIER_SYSTEM.md	Tier definitions, choosing the right tier
framework/DISCOVERY.md	How skills/specialists/agents are found and loaded
framework/CONCERNS_CHECKLIST.md	How concerns are wired into PRD authoring
framework/PIPELINE.md	Pipeline stages and gate checks
scaffold/SKILL_TEMPLATE.md	Quick-start template with checklist

---

Common Mistakes

Mistake	Fix
Too-broad globs	**/*.ts matches everything. Scope by directory: **/entities/**/*.ts
Missing "Use when..." in description	Descriptions MUST start with "Use when..." for searchability and consistent activation
Wrong tier	A skill that only applies when editing database entities is domain, not standards. A skill invoked by command is workflow, not domain.
Creating a skill when a config change suffices	If you just need to change a threshold, model, or stage override, edit jig.config.md
Creating a specialist for a one-off issue	One-off issues belong as logic reviewer examples. Only create a specialist for patterns (3+ occurrences).
Duplicating an existing artifact	Always search before creating. Team artifacts override core artifacts with the same name -- make sure that is intentional.
Not wiring into Concerns Checklist	If the artifact represents a cross-cutting design concern, add it to the checklist
SKILL.md over 500 lines	Move detailed patterns to reference/ subdirectory. Keep SKILL.md as core rules and quick reference.
Specialist prompt too broad	Each specialist should own one narrow concern. If the "What to Check" list exceeds 10 items, consider splitting.
Standards tier for "most" files	Standards means EVERY file. If it is "most" files, it is domain tier with broad globs.
Forgetting progressive disclosure	Skills over 500 lines need a reference table telling the agent when to load each sub-document
No verification after creation	Always run the verification step. A skill with invalid frontmatter or wrong location will not be discovered.

---

Integration

Called by:

• postmortem when a new artifact is needed (not just an edit to an existing one)
• Direct invocation via /extend

Related skills:

• review -- specialists created here are discovered by the review swarm
• prd -- concerns added to the checklist are surfaced during PRD authoring
• postmortem -- identifies gaps that lead to new artifacts

---

Quick Reference

Intent	Artifact	Key Decision
Enforce a universal rule	Standards skill	Are you sure it is EVERY file?
Capture domain patterns	Domain skill	Globs scoped to directories, not file types
Capture feature patterns	Feature skill	Narrower than domain -- one subsystem
Add a pipeline step	Workflow skill	Only loaded on explicit invocation
Add a review check (pattern)	Specialist	Model + tier + severity + narrow globs
Add a review check (reasoning)	Logic reviewer pattern	Add to existing logic-reviewer.md
Automate a task	Agent	Triggered by command or phrase
Change pipeline behavior	jig.config.md	No new artifact needed
Add PRD concern	Concerns checklist	Points to a skill or specialist

---

Pre-Commit Checklist

Before committing the new artifact:

• Name follows team convention (recommend domain prefix: be-, fe-, ops-, etc.)
• Description starts with "Use when..." (skills) or "Reviews..." (specialists)
• Tier matches activation pattern (see framework/TIER_SYSTEM.md)
• Globs scoped by code location, not broad applicability
• SKILL.md under 500 lines (heavy content in reference/)
• Cross-references explicit: **REQUIRED**: Use {skill} for {reason}
• Added to Concerns Checklist in jig.config.md (if applicable)
• No duplicate name in the discovery chain (or override is intentional)
• Verification step passed (frontmatter valid, location correct, globs tested)