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---
name: caveman
description: >
Ultra-compressed communication mode. Cuts token usage ~75% by dropping
filler, articles, and pleasantries while keeping full technical accuracy.
Use when user says "caveman mode", "talk like caveman", "use caveman",
"less tokens", "be brief", or invokes /caveman.
---
Respond terse like smart caveman. All technical substance stay. Only fluff die.
## Persistence
ACTIVE EVERY RESPONSE once triggered. No revert after many turns. No filler drift. Still active if unsure. Off only when user says "stop caveman" or "normal mode".
## Rules
Drop: articles (a/an/the), filler (just/really/basically/actually/simply), pleasantries (sure/certainly/of course/happy to), hedging. Fragments OK. Short synonyms (big not extensive, fix not "implement a solution for"). Abbreviate common terms (DB/auth/config/req/res/fn/impl). Strip conjunctions. Use arrows for causality (X -> Y). One word when one word enough.
Technical terms stay exact. Code blocks unchanged. Errors quoted exact.
Pattern: `[thing] [action] [reason]. [next step].`
Not: "Sure! I'd be happy to help you with that. The issue you're experiencing is likely caused by..."
Yes: "Bug in auth middleware. Token expiry check use `<` not `<=`. Fix:"
### Examples
**"Why React component re-render?"**
> Inline obj prop -> new ref -> re-render. `useMemo`.
**"Explain database connection pooling."**
> Pool = reuse DB conn. Skip handshake -> fast under load.
## Auto-Clarity Exception
Drop caveman temporarily for: security warnings, irreversible action confirmations, multi-step sequences where fragment order risks misread, user asks to clarify or repeats question. Resume caveman after clear part done.
Example -- destructive op:
> **Warning:** This will permanently delete all rows in the `users` table and cannot be undone.
>
> ```sql
> DROP TABLE users;
> ```
>
> Caveman resume. Verify backup exist first.

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---
name: design-an-interface
description: Generate multiple radically different interface designs for a module using parallel sub-agents. Use when user wants to design an API, explore interface options, compare module shapes, or mentions "design it twice".
---
# Design an Interface
Based on "Design It Twice" from "A Philosophy of Software Design": your first idea is unlikely to be the best. Generate multiple radically different designs, then compare.
## Workflow
### 1. Gather Requirements
Before designing, understand:
- [ ] What problem does this module solve?
- [ ] Who are the callers? (other modules, external users, tests)
- [ ] What are the key operations?
- [ ] Any constraints? (performance, compatibility, existing patterns)
- [ ] What should be hidden inside vs exposed?
Ask: "What does this module need to do? Who will use it?"
### 2. Generate Designs (Parallel Sub-Agents)
Spawn 3+ sub-agents simultaneously using Task tool. Each must produce a **radically different** approach.
```
Prompt template for each sub-agent:
Design an interface for: [module description]
Requirements: [gathered requirements]
Constraints for this design: [assign a different constraint to each agent]
- Agent 1: "Minimize method count - aim for 1-3 methods max"
- Agent 2: "Maximize flexibility - support many use cases"
- Agent 3: "Optimize for the most common case"
- Agent 4: "Take inspiration from [specific paradigm/library]"
Output format:
1. Interface signature (types/methods)
2. Usage example (how caller uses it)
3. What this design hides internally
4. Trade-offs of this approach
```
### 3. Present Designs
Show each design with:
1. **Interface signature** - types, methods, params
2. **Usage examples** - how callers actually use it in practice
3. **What it hides** - complexity kept internal
Present designs sequentially so user can absorb each approach before comparison.
### 4. Compare Designs
After showing all designs, compare them on:
- **Interface simplicity**: fewer methods, simpler params
- **General-purpose vs specialized**: flexibility vs focus
- **Implementation efficiency**: does shape allow efficient internals?
- **Depth**: small interface hiding significant complexity (good) vs large interface with thin implementation (bad)
- **Ease of correct use** vs **ease of misuse**
Discuss trade-offs in prose, not tables. Highlight where designs diverge most.
### 5. Synthesize
Often the best design combines insights from multiple options. Ask:
- "Which design best fits your primary use case?"
- "Any elements from other designs worth incorporating?"
## Evaluation Criteria
From "A Philosophy of Software Design":
**Interface simplicity**: Fewer methods, simpler params = easier to learn and use correctly.
**General-purpose**: Can handle future use cases without changes. But beware over-generalization.
**Implementation efficiency**: Does interface shape allow efficient implementation? Or force awkward internals?
**Depth**: Small interface hiding significant complexity = deep module (good). Large interface with thin implementation = shallow module (avoid).
## Anti-Patterns
- Don't let sub-agents produce similar designs - enforce radical difference
- Don't skip comparison - the value is in contrast
- Don't implement - this is purely about interface shape
- Don't evaluate based on implementation effort

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---
name: diagnose
description: Disciplined diagnosis loop for hard bugs and performance regressions. Reproduce → minimise → hypothesise → instrument → fix → regression-test. Use when user says "diagnose this" / "debug this", reports a bug, says something is broken/throwing/failing, or describes a performance regression.
---
# Diagnose
A discipline for hard bugs. Skip phases only when explicitly justified.
## Phase 1 — Build a feedback loop
**This is the skill.** Everything else is mechanical. If you have a fast, deterministic, agent-runnable pass/fail signal for the bug, you will find the cause — bisection, hypothesis-testing, and instrumentation all just consume that signal. If you don't have one, no amount of staring at code will save you.
Spend disproportionate effort here. **Be aggressive. Be creative. Refuse to give up.**
### Ways to construct one — try them in roughly this order
1. **Failing test** at whatever seam reaches the bug — unit, integration, e2e.
2. **Curl / HTTP script** against a running dev server.
3. **CLI invocation** with a fixture input, diffing stdout against a known-good snapshot.
4. **Headless browser script** (Playwright / Puppeteer) — drives the UI, asserts on DOM/console/network.
5. **Replay a captured trace.** Save a real network request / payload / event log to disk; replay it through the code path in isolation.
6. **Throwaway harness.** Spin up a minimal subset of the system (one service, mocked deps) that exercises the bug code path with a single function call.
7. **Property / fuzz loop.** If the bug is "sometimes wrong output", run 1000 random inputs and look for the failure mode.
8. **Bisection harness.** If the bug appeared between two known states (commit, dataset, version), automate "boot at state X, check, repeat" so you can `git bisect run` it.
9. **Differential loop.** Run the same input through old-version vs new-version (or two configs) and diff outputs.
10. **HITL bash script.** Last resort. If a human must click, drive _them_ with `scripts/hitl-loop.template.sh` so the loop is still structured. Captured output feeds back to you.
Build the right feedback loop, and the bug is 90% fixed.
### Iterate on the loop itself
Treat the loop as a product. Once you have _a_ loop, ask:
- Can I make it faster? (Cache setup, skip unrelated init, narrow the test scope.)
- Can I make the signal sharper? (Assert on the specific symptom, not "didn't crash".)
- Can I make it more deterministic? (Pin time, seed RNG, isolate filesystem, freeze network.)
A 30-second flaky loop is barely better than no loop. A 2-second deterministic loop is a debugging superpower.
### Non-deterministic bugs
The goal is not a clean repro but a **higher reproduction rate**. Loop the trigger 100×, parallelise, add stress, narrow timing windows, inject sleeps. A 50%-flake bug is debuggable; 1% is not — keep raising the rate until it's debuggable.
### When you genuinely cannot build a loop
Stop and say so explicitly. List what you tried. Ask the user for: (a) access to whatever environment reproduces it, (b) a captured artifact (HAR file, log dump, core dump, screen recording with timestamps), or (c) permission to add temporary production instrumentation. Do **not** proceed to hypothesise without a loop.
Do not proceed to Phase 2 until you have a loop you believe in.
## Phase 2 — Reproduce
Run the loop. Watch the bug appear.
Confirm:
- [ ] The loop produces the failure mode the **user** described — not a different failure that happens to be nearby. Wrong bug = wrong fix.
- [ ] The failure is reproducible across multiple runs (or, for non-deterministic bugs, reproducible at a high enough rate to debug against).
- [ ] You have captured the exact symptom (error message, wrong output, slow timing) so later phases can verify the fix actually addresses it.
Do not proceed until you reproduce the bug.
## Phase 3 — Hypothesise
Generate **3–5 ranked hypotheses** before testing any of them. Single-hypothesis generation anchors on the first plausible idea.
Each hypothesis must be **falsifiable**: state the prediction it makes.
> Format: "If <X> is the cause, then <changing Y> will make the bug disappear / <changing Z> will make it worse."
If you cannot state the prediction, the hypothesis is a vibe — discard or sharpen it.
**Show the ranked list to the user before testing.** They often have domain knowledge that re-ranks instantly ("we just deployed a change to #3"), or know hypotheses they've already ruled out. Cheap checkpoint, big time saver. Don't block on it — proceed with your ranking if the user is AFK.
## Phase 4 — Instrument
Each probe must map to a specific prediction from Phase 3. **Change one variable at a time.**
Tool preference:
1. **Debugger / REPL inspection** if the env supports it. One breakpoint beats ten logs.
2. **Targeted logs** at the boundaries that distinguish hypotheses.
3. Never "log everything and grep".
**Tag every debug log** with a unique prefix, e.g. `[DEBUG-a4f2]`. Cleanup at the end becomes a single grep. Untagged logs survive; tagged logs die.
**Perf branch.** For performance regressions, logs are usually wrong. Instead: establish a baseline measurement (timing harness, `performance.now()`, profiler, query plan), then bisect. Measure first, fix second.
## Phase 5 — Fix + regression test
Write the regression test **before the fix** — but only if there is a **correct seam** for it.
A correct seam is one where the test exercises the **real bug pattern** as it occurs at the call site. If the only available seam is too shallow (single-caller test when the bug needs multiple callers, unit test that can't replicate the chain that triggered the bug), a regression test there gives false confidence.
**If no correct seam exists, that itself is the finding.** Note it. The codebase architecture is preventing the bug from being locked down. Flag this for the next phase.
If a correct seam exists:
1. Turn the minimised repro into a failing test at that seam.
2. Watch it fail.
3. Apply the fix.
4. Watch it pass.
5. Re-run the Phase 1 feedback loop against the original (un-minimised) scenario.
## Phase 6 — Cleanup + post-mortem
Required before declaring done:
- [ ] Original repro no longer reproduces (re-run the Phase 1 loop)
- [ ] Regression test passes (or absence of seam is documented)
- [ ] All `[DEBUG-...]` instrumentation removed (`grep` the prefix)
- [ ] Throwaway prototypes deleted (or moved to a clearly-marked debug location)
- [ ] The hypothesis that turned out correct is stated in the commit / PR message — so the next debugger learns
**Then ask: what would have prevented this bug?** If the answer involves architectural change (no good test seam, tangled callers, hidden coupling) hand off to the `/improve-codebase-architecture` skill with the specifics. Make the recommendation **after** the fix is in, not before — you have more information now than when you started.

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#!/usr/bin/env bash
# Human-in-the-loop reproduction loop.
# Copy this file, edit the steps below, and run it.
# The agent runs the script; the user follows prompts in their terminal.
#
# Usage:
# bash hitl-loop.template.sh
#
# Two helpers:
# step "<instruction>" → show instruction, wait for Enter
# capture VAR "<question>" → show question, read response into VAR
#
# At the end, captured values are printed as KEY=VALUE for the agent to parse.
set -euo pipefail
step() {
printf '\n>>> %s\n' "$1"
read -r -p " [Enter when done] " _
}
capture() {
local var="$1" question="$2" answer
printf '\n>>> %s\n' "$question"
read -r -p " > " answer
printf -v "$var" '%s' "$answer"
}
# --- edit below ---------------------------------------------------------
step "Open the app at http://localhost:3000 and sign in."
capture ERRORED "Click the 'Export' button. Did it throw an error? (y/n)"
capture ERROR_MSG "Paste the error message (or 'none'):"
# --- edit above ---------------------------------------------------------
printf '\n--- Captured ---\n'
printf 'ERRORED=%s\n' "$ERRORED"
printf 'ERROR_MSG=%s\n' "$ERROR_MSG"

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# ADR Format
ADRs live in `docs/adr/` and use sequential numbering: `0001-slug.md`, `0002-slug.md`, etc.
Create the `docs/adr/` directory lazily — only when the first ADR is needed.
## Template
```md
# {Short title of the decision}
{1-3 sentences: what's the context, what did we decide, and why.}
```
That's it. An ADR can be a single paragraph. The value is in recording *that* a decision was made and *why* — not in filling out sections.
## Optional sections
Only include these when they add genuine value. Most ADRs won't need them.
- **Status** frontmatter (`proposed | accepted | deprecated | superseded by ADR-NNNN`) — useful when decisions are revisited
- **Considered Options** — only when the rejected alternatives are worth remembering
- **Consequences** — only when non-obvious downstream effects need to be called out
## Numbering
Scan `docs/adr/` for the highest existing number and increment by one.
## When to offer an ADR
All three of these must be true:
1. **Hard to reverse** — the cost of changing your mind later is meaningful
2. **Surprising without context** — a future reader will look at the code and wonder "why on earth did they do it this way?"
3. **The result of a real trade-off** — there were genuine alternatives and you picked one for specific reasons
If a decision is easy to reverse, skip it — you'll just reverse it. If it's not surprising, nobody will wonder why. If there was no real alternative, there's nothing to record beyond "we did the obvious thing."
### What qualifies
- **Architectural shape.** "We're using a monorepo." "The write model is event-sourced, the read model is projected into Postgres."
- **Integration patterns between contexts.** "Ordering and Billing communicate via domain events, not synchronous HTTP."
- **Technology choices that carry lock-in.** Database, message bus, auth provider, deployment target. Not every library — just the ones that would take a quarter to swap out.
- **Boundary and scope decisions.** "Customer data is owned by the Customer context; other contexts reference it by ID only." The explicit no-s are as valuable as the yes-s.
- **Deliberate deviations from the obvious path.** "We're using manual SQL instead of an ORM because X." Anything where a reasonable reader would assume the opposite. These stop the next engineer from "fixing" something that was deliberate.
- **Constraints not visible in the code.** "We can't use AWS because of compliance requirements." "Response times must be under 200ms because of the partner API contract."
- **Rejected alternatives when the rejection is non-obvious.** If you considered GraphQL and picked REST for subtle reasons, record it — otherwise someone will suggest GraphQL again in six months.

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# CONTEXT.md Format
## Structure
```md
# {Context Name}
{One or two sentence description of what this context is and why it exists.}
## Language
**Order**:
{A concise description of the term}
_Avoid_: Purchase, transaction
**Invoice**:
A request for payment sent to a customer after delivery.
_Avoid_: Bill, payment request
**Customer**:
A person or organization that places orders.
_Avoid_: Client, buyer, account
## Relationships
- An **Order** produces one or more **Invoices**
- An **Invoice** belongs to exactly one **Customer**
## Example dialogue
> **Dev:** "When a **Customer** places an **Order**, do we create the **Invoice** immediately?"
> **Domain expert:** "No — an **Invoice** is only generated once a **Fulfillment** is confirmed."
## Flagged ambiguities
- "account" was used to mean both **Customer** and **User** — resolved: these are distinct concepts.
```
## Rules
- **Be opinionated.** When multiple words exist for the same concept, pick the best one and list the others as aliases to avoid.
- **Flag conflicts explicitly.** If a term is used ambiguously, call it out in "Flagged ambiguities" with a clear resolution.
- **Keep definitions tight.** One sentence max. Define what it IS, not what it does.
- **Show relationships.** Use bold term names and express cardinality where obvious.
- **Only include terms specific to this project's context.** General programming concepts (timeouts, error types, utility patterns) don't belong even if the project uses them extensively. Before adding a term, ask: is this a concept unique to this context, or a general programming concept? Only the former belongs.
- **Group terms under subheadings** when natural clusters emerge. If all terms belong to a single cohesive area, a flat list is fine.
- **Write an example dialogue.** A conversation between a dev and a domain expert that demonstrates how the terms interact naturally and clarifies boundaries between related concepts.
## Single vs multi-context repos
**Single context (most repos):** One `CONTEXT.md` at the repo root.
**Multiple contexts:** A `CONTEXT-MAP.md` at the repo root lists the contexts, where they live, and how they relate to each other:
```md
# Context Map
## Contexts
- [Ordering](./src/ordering/CONTEXT.md) — receives and tracks customer orders
- [Billing](./src/billing/CONTEXT.md) — generates invoices and processes payments
- [Fulfillment](./src/fulfillment/CONTEXT.md) — manages warehouse picking and shipping
## Relationships
- **Ordering → Fulfillment**: Ordering emits `OrderPlaced` events; Fulfillment consumes them to start picking
- **Fulfillment → Billing**: Fulfillment emits `ShipmentDispatched` events; Billing consumes them to generate invoices
- **Ordering ↔ Billing**: Shared types for `CustomerId` and `Money`
```
The skill infers which structure applies:
- If `CONTEXT-MAP.md` exists, read it to find contexts
- If only a root `CONTEXT.md` exists, single context
- If neither exists, create a root `CONTEXT.md` lazily when the first term is resolved
When multiple contexts exist, infer which one the current topic relates to. If unclear, ask.

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---
name: domain-model
description: Grilling session that challenges your plan against the existing domain model, sharpens terminology, and updates documentation (CONTEXT.md, ADRs) inline as decisions crystallise. Use when user wants to stress-test a plan against their project's language and documented decisions.
disable-model-invocation: true
---
Interview me relentlessly about every aspect of this plan until we reach a shared understanding. Walk down each branch of the design tree, resolving dependencies between decisions one-by-one. For each question, provide your recommended answer.
Ask the questions one at a time, waiting for feedback on each question before continuing.
If a question can be answered by exploring the codebase, explore the codebase instead.
## Domain awareness
During codebase exploration, also look for existing documentation:
### File structure
Most repos have a single context:
```
/
├── CONTEXT.md
├── docs/
│ └── adr/
│ ├── 0001-event-sourced-orders.md
│ └── 0002-postgres-for-write-model.md
└── src/
```
If a `CONTEXT-MAP.md` exists at the root, the repo has multiple contexts. The map points to where each one lives:
```
/
├── CONTEXT-MAP.md
├── docs/
│ └── adr/ ← system-wide decisions
├── src/
│ ├── ordering/
│ │ ├── CONTEXT.md
│ │ └── docs/adr/ ← context-specific decisions
│ └── billing/
│ ├── CONTEXT.md
│ └── docs/adr/
```
Create files lazily — only when you have something to write. If no `CONTEXT.md` exists, create one when the first term is resolved. If no `docs/adr/` exists, create it when the first ADR is needed.
## During the session
### Challenge against the glossary
When the user uses a term that conflicts with the existing language in `CONTEXT.md`, call it out immediately. "Your glossary defines 'cancellation' as X, but you seem to mean Y — which is it?"
### Sharpen fuzzy language
When the user uses vague or overloaded terms, propose a precise canonical term. "You're saying 'account' — do you mean the Customer or the User? Those are different things."
### Discuss concrete scenarios
When domain relationships are being discussed, stress-test them with specific scenarios. Invent scenarios that probe edge cases and force the user to be precise about the boundaries between concepts.
### Cross-reference with code
When the user states how something works, check whether the code agrees. If you find a contradiction, surface it: "Your code cancels entire Orders, but you just said partial cancellation is possible — which is right?"
### Update CONTEXT.md inline
When a term is resolved, update `CONTEXT.md` right there. Don't batch these up — capture them as they happen. Use the format in [CONTEXT-FORMAT.md](./CONTEXT-FORMAT.md).
Don't couple `CONTEXT.md` to implementation details. Only include terms that are meaningful to domain experts.
### Offer ADRs sparingly
Only offer to create an ADR when all three are true:
1. **Hard to reverse** — the cost of changing your mind later is meaningful
2. **Surprising without context** — a future reader will wonder "why did they do it this way?"
3. **The result of a real trade-off** — there were genuine alternatives and you picked one for specific reasons
If any of the three is missing, skip the ADR. Use the format in [ADR-FORMAT.md](./ADR-FORMAT.md).

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---
name: edit-article
description: Edit and improve articles by restructuring sections, improving clarity, and tightening prose. Use when user wants to edit, revise, or improve an article draft.
---
1. First, divide the article into sections based on its headings. Think about the main points you want to make during those sections.
Consider that information is a directed acyclic graph, and that pieces of information can depend on other pieces of information. Make sure that the order of the sections and their contents respects these dependencies.
Confirm the sections with the user.
2. For each section:
2a. Rewrite the section to improve clarity, coherence, and flow. Use maximum 240 characters per paragraph.

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---
name: git-guardrails-claude-code
description: Set up Claude Code hooks to block dangerous git commands (push, reset --hard, clean, branch -D, etc.) before they execute. Use when user wants to prevent destructive git operations, add git safety hooks, or block git push/reset in Claude Code.
---
# Setup Git Guardrails
Sets up a PreToolUse hook that intercepts and blocks dangerous git commands before Claude executes them.
## What Gets Blocked
- `git push` (all variants including `--force`)
- `git reset --hard`
- `git clean -f` / `git clean -fd`
- `git branch -D`
- `git checkout .` / `git restore .`
When blocked, Claude sees a message telling it that it does not have authority to access these commands.
## Steps
### 1. Ask scope
Ask the user: install for **this project only** (`.claude/settings.json`) or **all projects** (`~/.claude/settings.json`)?
### 2. Copy the hook script
The bundled script is at: [scripts/block-dangerous-git.sh](scripts/block-dangerous-git.sh)
Copy it to the target location based on scope:
- **Project**: `.claude/hooks/block-dangerous-git.sh`
- **Global**: `~/.claude/hooks/block-dangerous-git.sh`
Make it executable with `chmod +x`.
### 3. Add hook to settings
Add to the appropriate settings file:
**Project** (`.claude/settings.json`):
```json
{
"hooks": {
"PreToolUse": [
{
"matcher": "Bash",
"hooks": [
{
"type": "command",
"command": "\"$CLAUDE_PROJECT_DIR\"/.claude/hooks/block-dangerous-git.sh"
}
]
}
]
}
}
```
**Global** (`~/.claude/settings.json`):
```json
{
"hooks": {
"PreToolUse": [
{
"matcher": "Bash",
"hooks": [
{
"type": "command",
"command": "~/.claude/hooks/block-dangerous-git.sh"
}
]
}
]
}
}
```
If the settings file already exists, merge the hook into existing `hooks.PreToolUse` array — don't overwrite other settings.
### 4. Ask about customization
Ask if user wants to add or remove any patterns from the blocked list. Edit the copied script accordingly.
### 5. Verify
Run a quick test:
```bash
echo '{"tool_input":{"command":"git push origin main"}}' | <path-to-script>
```
Should exit with code 2 and print a BLOCKED message to stderr.

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#!/bin/bash
INPUT=$(cat)
COMMAND=$(echo "$INPUT" | jq -r '.tool_input.command')
DANGEROUS_PATTERNS=(
"git push"
"git reset --hard"
"git clean -fd"
"git clean -f"
"git branch -D"
"git checkout \."
"git restore \."
"push --force"
"reset --hard"
)
for pattern in "${DANGEROUS_PATTERNS[@]}"; do
if echo "$COMMAND" | grep -qE "$pattern"; then
echo "BLOCKED: '$COMMAND' matches dangerous pattern '$pattern'. The user has prevented you from doing this." >&2
exit 2
fi
done
exit 0

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# Writing Agent Briefs
An agent brief is a structured comment posted on a GitHub issue when it moves to `ready-for-agent`. It is the authoritative specification that an AFK agent will work from. The original issue body and discussion are context — the agent brief is the contract.
## Principles
### Durability over precision
The issue may sit in `ready-for-agent` for days or weeks. The codebase will change in the meantime. Write the brief so it stays useful even as files are renamed, moved, or refactored.
- **Do** describe interfaces, types, and behavioral contracts
- **Do** name specific types, function signatures, or config shapes that the agent should look for or modify
- **Don't** reference file paths — they go stale
- **Don't** reference line numbers
- **Don't** assume the current implementation structure will remain the same
### Behavioral, not procedural
Describe **what** the system should do, not **how** to implement it. The agent will explore the codebase fresh and make its own implementation decisions.
- **Good:** "The `SkillConfig` type should accept an optional `schedule` field of type `CronExpression`"
- **Bad:** "Open src/types/skill.ts and add a schedule field on line 42"
- **Good:** "When a user runs `/triage` with no arguments, they should see a summary of issues needing attention"
- **Bad:** "Add a switch statement in the main handler function"
### Complete acceptance criteria
The agent needs to know when it's done. Every agent brief must have concrete, testable acceptance criteria. Each criterion should be independently verifiable.
- **Good:** "Running `gh issue list --label needs-triage` returns issues that have been through initial classification"
- **Bad:** "Triage should work correctly"
### Explicit scope boundaries
State what is out of scope. This prevents the agent from gold-plating or making assumptions about adjacent features.
## Template
```markdown
## Agent Brief
**Category:** bug / enhancement
**Summary:** one-line description of what needs to happen
**Current behavior:**
Describe what happens now. For bugs, this is the broken behavior.
For enhancements, this is the status quo the feature builds on.
**Desired behavior:**
Describe what should happen after the agent's work is complete.
Be specific about edge cases and error conditions.
**Key interfaces:**
- `TypeName` — what needs to change and why
- `functionName()` return type — what it currently returns vs what it should return
- Config shape — any new configuration options needed
**Acceptance criteria:**
- [ ] Specific, testable criterion 1
- [ ] Specific, testable criterion 2
- [ ] Specific, testable criterion 3
**Out of scope:**
- Thing that should NOT be changed or addressed in this issue
- Adjacent feature that might seem related but is separate
```
## Examples
### Good agent brief (bug)
```markdown
## Agent Brief
**Category:** bug
**Summary:** Skill description truncation drops mid-word, producing broken output
**Current behavior:**
When a skill description exceeds 1024 characters, it is truncated at exactly
1024 characters regardless of word boundaries. This produces descriptions
that end mid-word (e.g. "Use when the user wants to confi").
**Desired behavior:**
Truncation should break at the last word boundary before 1024 characters
and append "..." to indicate truncation.
**Key interfaces:**
- The `SkillMetadata` type's `description` field — no type change needed,
but the validation/processing logic that populates it needs to respect
word boundaries
- Any function that reads SKILL.md frontmatter and extracts the description
**Acceptance criteria:**
- [ ] Descriptions under 1024 chars are unchanged
- [ ] Descriptions over 1024 chars are truncated at the last word boundary
before 1024 chars
- [ ] Truncated descriptions end with "..."
- [ ] The total length including "..." does not exceed 1024 chars
**Out of scope:**
- Changing the 1024 char limit itself
- Multi-line description support
```
### Good agent brief (enhancement)
```markdown
## Agent Brief
**Category:** enhancement
**Summary:** Add `.out-of-scope/` directory support for tracking rejected feature requests
**Current behavior:**
When a feature request is rejected, the issue is closed with a `wontfix` label
and a comment. There is no persistent record of the decision or reasoning.
Future similar requests require the maintainer to recall or search for the
prior discussion.
**Desired behavior:**
Rejected feature requests should be documented in `.out-of-scope/<concept>.md`
files that capture the decision, reasoning, and links to all issues that
requested the feature. When triaging new issues, these files should be
checked for matches.
**Key interfaces:**
- Markdown file format in `.out-of-scope/` — each file should have a
`# Concept Name` heading, a `**Decision:**` line, a `**Reason:**` line,
and a `**Prior requests:**` list with issue links
- The triage workflow should read all `.out-of-scope/*.md` files early
and match incoming issues against them by concept similarity
**Acceptance criteria:**
- [ ] Closing a feature as wontfix creates/updates a file in `.out-of-scope/`
- [ ] The file includes the decision, reasoning, and link to the closed issue
- [ ] If a matching `.out-of-scope/` file already exists, the new issue is
appended to its "Prior requests" list rather than creating a duplicate
- [ ] During triage, existing `.out-of-scope/` files are checked and surfaced
when a new issue matches a prior rejection
**Out of scope:**
- Automated matching (human confirms the match)
- Reopening previously rejected features
- Bug reports (only enhancement rejections go to `.out-of-scope/`)
```
### Bad agent brief
```markdown
## Agent Brief
**Summary:** Fix the triage bug
**What to do:**
The triage thing is broken. Look at the main file and fix it.
The function around line 150 has the issue.
**Files to change:**
- src/triage/handler.ts (line 150)
- src/types.ts (line 42)
```
This is bad because:
- No category
- Vague description ("the triage thing is broken")
- References file paths and line numbers that will go stale
- No acceptance criteria
- No scope boundaries
- No description of current vs desired behavior

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# Out-of-Scope Knowledge Base
The `.out-of-scope/` directory in a repo stores persistent records of rejected feature requests. It serves two purposes:
1. **Institutional memory** — why a feature was rejected, so the reasoning isn't lost when the issue is closed
2. **Deduplication** — when a new issue comes in that matches a prior rejection, the skill can surface the previous decision instead of re-litigating it
## Directory structure
```
.out-of-scope/
├── dark-mode.md
├── plugin-system.md
└── graphql-api.md
```
One file per **concept**, not per issue. Multiple issues requesting the same thing are grouped under one file.
## File format
The file should be written in a relaxed, readable style — more like a short design document than a database entry. Use paragraphs, code samples, and examples to make the reasoning clear and useful to someone encountering it for the first time.
```markdown
# Dark Mode
This project does not support dark mode or user-facing theming.
## Why this is out of scope
The rendering pipeline assumes a single color palette defined in
`ThemeConfig`. Supporting multiple themes would require:
- A theme context provider wrapping the entire component tree
- Per-component theme-aware style resolution
- A persistence layer for user theme preferences
This is a significant architectural change that doesn't align with the
project's focus on content authoring. Theming is a concern for downstream
consumers who embed or redistribute the output.
```ts
// The current ThemeConfig interface is not designed for runtime switching:
interface ThemeConfig {
colors: ColorPalette; // single palette, resolved at build time
fonts: FontStack;
}
```
## Prior requests
- #42 — "Add dark mode support"
- #87 — "Night theme for accessibility"
- #134 — "Dark theme option"
```
### Naming the file
Use a short, descriptive kebab-case name for the concept: `dark-mode.md`, `plugin-system.md`, `graphql-api.md`. The name should be recognizable enough that someone browsing the directory understands what was rejected without opening the file.
### Writing the reason
The reason should be substantive — not "we don't want this" but why. Good reasons reference:
- Project scope or philosophy ("This project focuses on X; theming is a downstream concern")
- Technical constraints ("Supporting this would require Y, which conflicts with our Z architecture")
- Strategic decisions ("We chose to use A instead of B because...")
The reason should be durable. Avoid referencing temporary circumstances ("we're too busy right now") — those aren't real rejections, they're deferrals.
## When to check `.out-of-scope/`
During triage (Step 1: Gather context), read all files in `.out-of-scope/`. When evaluating a new issue:
- Check if the request matches an existing out-of-scope concept
- Matching is by concept similarity, not keyword — "night theme" matches `dark-mode.md`
- If there's a match, surface it to the maintainer: "This is similar to `.out-of-scope/dark-mode.md` — we rejected this before because [reason]. Do you still feel the same way?"
The maintainer may:
- **Confirm** — the new issue gets added to the existing file's "Prior requests" list, then closed
- **Reconsider** — the out-of-scope file gets deleted or updated, and the issue proceeds through normal triage
- **Disagree** — the issues are related but distinct, proceed with normal triage
## When to write to `.out-of-scope/`
Only when an **enhancement** (not a bug) is rejected as `wontfix`. The flow:
1. Maintainer decides a feature request is out of scope
2. Check if a matching `.out-of-scope/` file already exists
3. If yes: append the new issue to the "Prior requests" list
4. If no: create a new file with the concept name, decision, reason, and first prior request
5. Post a comment on the issue explaining the decision and mentioning the `.out-of-scope/` file
6. Close the issue with the `wontfix` label
## Updating or removing out-of-scope files
If the maintainer changes their mind about a previously rejected concept:
- Delete the `.out-of-scope/` file
- The skill does not need to reopen old issues — they're historical records
- The new issue that triggered the reconsideration proceeds through normal triage

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---
name: github-triage
description: Triage GitHub issues through a label-based state machine. Use when user wants to create an issue, triage issues, review incoming bugs or feature requests, prepare issues for an AFK agent, or manage issue workflow.
---
# GitHub Issue Triage
Triage issues in the current repo using a label-based state machine. Infer the repo from `git remote`. Use `gh` for all GitHub operations.
## AI Disclaimer
Every comment or issue posted to GitHub during triage **must** include the following disclaimer at the top of the comment body, before any other content:
```
> *This was generated by AI during triage.*
```
## Reference docs
- [AGENT-BRIEF.md](AGENT-BRIEF.md) — how to write durable agent briefs
- [OUT-OF-SCOPE.md](OUT-OF-SCOPE.md) — how the `.out-of-scope/` knowledge base works
## Labels
| Label | Type | Description |
| ----------------- | -------- | ---------------------------------------- |
| `bug` | Category | Something is broken |
| `enhancement` | Category | New feature or improvement |
| `needs-triage` | State | Maintainer needs to evaluate this issue |
| `needs-info` | State | Waiting on reporter for more information |
| `ready-for-agent` | State | Fully specified, ready for AFK agent |
| `ready-for-human` | State | Requires human implementation |
| `wontfix` | State | Will not be actioned |
Every issue should have exactly **one** state label and **one** category label. If an issue has conflicting state labels (e.g. both `needs-triage` and `ready-for-agent`), flag the conflict and ask the maintainer which state is correct before doing anything else. Provide a recommendation.
## State Machine
| Current State | Can transition to | Who triggers it | What happens |
| -------------- | ----------------- | ---------------------- | -------------------------------------------------------------------------------------------------------------------- |
| `unlabeled` | `needs-triage` | Skill (on first look) | Issue needs maintainer evaluation. Skill applies label after presenting recommendation. |
| `unlabeled` | `ready-for-agent` | Maintainer (via skill) | Issue is already well-specified and agent-suitable. Skill writes agent brief comment, applies label. |
| `unlabeled` | `ready-for-human` | Maintainer (via skill) | Issue requires human implementation. Skill writes a brief comment summarizing the task, applies label. |
| `unlabeled` | `wontfix` | Maintainer (via skill) | Issue is spam, duplicate, or out of scope. Skill closes with comment (and writes `.out-of-scope/` for enhancements). |
| `needs-triage` | `needs-info` | Maintainer (via skill) | Issue is underspecified. Skill posts triage notes capturing progress so far + questions for reporter. |
| `needs-triage` | `ready-for-agent` | Maintainer (via skill) | Grilling session complete, agent-suitable. Skill writes agent brief comment, applies label. |
| `needs-triage` | `ready-for-human` | Maintainer (via skill) | Grilling session complete, needs human. Skill writes a brief comment summarizing the task, applies label. |
| `needs-triage` | `wontfix` | Maintainer (via skill) | Maintainer decides not to action. Skill closes with comment (and writes `.out-of-scope/` for enhancements). |
| `needs-info` | `needs-triage` | Skill (detects reply) | Reporter has replied. Skill surfaces to maintainer for re-evaluation. |
An issue can only move along these transitions. The maintainer can override any state directly (see Quick State Override below), but the skill should flag if the transition is unusual.
## Invocation
The maintainer invokes `/github-triage` then describes what they want in natural language. The skill interprets the request and takes the appropriate action.
Example requests:
- "Show me anything that needs my attention"
- "Let's look at #42"
- "Move #42 to ready-for-agent"
- "What's ready for agents to pick up?"
- "Are there any unlabeled issues?"
## Workflow: Show What Needs Attention
When the maintainer asks for an overview, query GitHub and present a summary grouped into three buckets:
1. **Unlabeled issues** — new, no labels at all. These have never been triaged.
2. **`needs-triage` issues** — maintainer needs to evaluate or continue evaluating.
3. **`needs-info` issues with new activity** — the reporter has commented since the last triage notes comment. Check comment timestamps to determine this.
Display counts per group. Within each group, show issues oldest first (longest-waiting gets attention first). For each issue, show: number, title, age, and a one-line summary of the issue body.
Let the maintainer pick which issue to dive into.
## Workflow: Triage a Specific Issue
### Step 1: Gather context
Before presenting anything to the maintainer:
- Read the full issue: body, all comments, all labels, who reported it, when
- If there are prior triage notes comments (from previous sessions), parse them to understand what has already been established
- Explore the codebase to build context — understand the domain, relevant interfaces, and existing behavior related to the issue
- Read `.out-of-scope/*.md` files and check if this issue matches or is similar to a previously rejected concept
### Step 2: Present a recommendation
Tell the maintainer:
- **Category recommendation:** bug or enhancement, with reasoning
- **State recommendation:** where this issue should go, with reasoning
- If it matches a prior out-of-scope rejection, surface that: "This is similar to `.out-of-scope/concept-name.md` — we rejected this before because X. Do you still feel the same way?"
- A brief summary of what you found in the codebase that's relevant
Then wait for the maintainer's direction. They may:
- Agree and ask you to apply labels → do it
- Want to flesh it out → start a /domain-model session
- Override with a different state → apply their choice
- Want to discuss → have a conversation
### Step 3: Bug reproduction (bugs only)
If the issue is categorized as a bug, attempt to reproduce it before starting a /domain-model session. This will vary by codebase, but do your best:
- Read the reporter's reproduction steps (if provided)
- Explore the codebase to understand the relevant code paths
- Try to reproduce the bug: run tests, execute commands, or trace the logic to confirm the reported behavior
- If reproduction succeeds, report what you found to the maintainer — include the specific behavior you observed and where in the code it originates
- If reproduction fails, report that too — the bug may be environment-specific, already fixed, or the report may be inaccurate
- If the report lacks enough detail to attempt reproduction, note that — this is a strong signal the issue should move to `needs-info`
The reproduction attempt informs the /domain-model session and the agent brief. A confirmed reproduction with a known code path makes for a much stronger brief.
### Step 4: /domain-model session (if needed)
If the issue needs to be fleshed out before it's ready for an agent, interview the maintainer to build a complete specification. Use the /domain-model skill.
### Step 5: Apply the outcome
Depending on the outcome:
- **ready-for-agent** — post an agent brief comment (see [AGENT-BRIEF.md](AGENT-BRIEF.md))
- **ready-for-human** — post a comment summarizing the task, what was established during triage, and why it needs human implementation. Use the same structure as an agent brief but note the reason it can't be delegated to an agent (e.g. requires judgment calls, external system access, design decisions, or manual testing).
- **needs-info** — post triage notes with progress so far and questions for the reporter (see Needs Info Output below)
- **wontfix (bug)** — post a polite comment explaining why, then close the issue
- **wontfix (enhancement)** — write to `.out-of-scope/`, post a comment linking to it, then close the issue (see [OUT-OF-SCOPE.md](OUT-OF-SCOPE.md))
- **needs-triage** — apply the label. Optionally leave a comment if there's partial progress to capture.
## Workflow: Quick State Override
When the maintainer explicitly tells you to move an issue to a specific state (e.g. "move #42 to ready-for-agent"), trust their judgment and apply the label directly.
Still show a confirmation of what you're about to do: which labels will be added/removed, and whether you'll post a comment or close the issue. But skip the /domain-model session entirely.
If moving to `ready-for-agent` without a /domain-model session, ask the maintainer if they want to write a brief agent brief comment or skip it.
## Needs Info Output
When moving an issue to `needs-info`, post a comment that captures the interview progress and tells the reporter what's needed:
```markdown
## Triage Notes
**What we've established so far:**
- point 1
- point 2
**What we still need from you (@reporter):**
- question 1
- question 2
```
Include everything resolved during the /domain-model session in "established so far" — this work should not be lost. The questions for the reporter should be specific and actionable, not vague ("please provide more info").
## Resuming Previous Sessions
When triaging an issue that already has triage notes from a previous session:
1. Read all comments to find prior triage notes
2. Parse what was already established
3. Check if the reporter has answered any outstanding questions
4. Present the maintainer with an updated picture: "Here's where we left off, and here's what the reporter has said since"
5. Continue the /domain-model session from where it stopped — do not re-ask resolved questions

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---
name: grill-me
description: Interview the user relentlessly about a plan or design until reaching shared understanding, resolving each branch of the decision tree. Use when user wants to stress-test a plan, get grilled on their design, or mentions "grill me".
---
Interview me relentlessly about every aspect of this plan until we reach a shared understanding. Walk down each branch of the design tree, resolving dependencies between decisions one-by-one. For each question, provide your recommended answer.
Ask the questions one at a time.
If a question can be answered by exploring the codebase, explore the codebase instead.

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# Deepening
How to deepen a cluster of shallow modules safely, given its dependencies. Assumes the vocabulary in [LANGUAGE.md](LANGUAGE.md) — **module**, **interface**, **seam**, **adapter**.
## Dependency categories
When assessing a candidate for deepening, classify its dependencies. The category determines how the deepened module is tested across its seam.
### 1. In-process
Pure computation, in-memory state, no I/O. Always deepenable — merge the modules and test through the new interface directly. No adapter needed.
### 2. Local-substitutable
Dependencies that have local test stand-ins (PGLite for Postgres, in-memory filesystem). Deepenable if the stand-in exists. The deepened module is tested with the stand-in running in the test suite. The seam is internal; no port at the module's external interface.
### 3. Remote but owned (Ports & Adapters)
Your own services across a network boundary (microservices, internal APIs). Define a **port** (interface) at the seam. The deep module owns the logic; the transport is injected as an **adapter**. Tests use an in-memory adapter. Production uses an HTTP/gRPC/queue adapter.
Recommendation shape: *"Define a port at the seam, implement an HTTP adapter for production and an in-memory adapter for testing, so the logic sits in one deep module even though it's deployed across a network."*
### 4. True external (Mock)
Third-party services (Stripe, Twilio, etc.) you don't control. The deepened module takes the external dependency as an injected port; tests provide a mock adapter.
## Seam discipline
- **One adapter means a hypothetical seam. Two adapters means a real one.** Don't introduce a port unless at least two adapters are justified (typically production + test). A single-adapter seam is just indirection.
- **Internal seams vs external seams.** A deep module can have internal seams (private to its implementation, used by its own tests) as well as the external seam at its interface. Don't expose internal seams through the interface just because tests use them.
## Testing strategy: replace, don't layer
- Old unit tests on shallow modules become waste once tests at the deepened module's interface exist — delete them.
- Write new tests at the deepened module's interface. The **interface is the test surface**.
- Tests assert on observable outcomes through the interface, not internal state.
- Tests should survive internal refactors — they describe behaviour, not implementation. If a test has to change when the implementation changes, it's testing past the interface.

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# Interface Design
When the user wants to explore alternative interfaces for a chosen deepening candidate, use this parallel sub-agent pattern. Based on "Design It Twice" (Ousterhout) — your first idea is unlikely to be the best.
Uses the vocabulary in [LANGUAGE.md](LANGUAGE.md) — **module**, **interface**, **seam**, **adapter**, **leverage**.
## Process
### 1. Frame the problem space
Before spawning sub-agents, write a user-facing explanation of the problem space for the chosen candidate:
- The constraints any new interface would need to satisfy
- The dependencies it would rely on, and which category they fall into (see [DEEPENING.md](DEEPENING.md))
- A rough illustrative code sketch to ground the constraints — not a proposal, just a way to make the constraints concrete
Show this to the user, then immediately proceed to Step 2. The user reads and thinks while the sub-agents work in parallel.
### 2. Spawn sub-agents
Spawn 3+ sub-agents in parallel using the Agent tool. Each must produce a **radically different** interface for the deepened module.
Prompt each sub-agent with a separate technical brief (file paths, coupling details, dependency category from [DEEPENING.md](DEEPENING.md), what sits behind the seam). The brief is independent of the user-facing problem-space explanation in Step 1. Give each agent a different design constraint:
- Agent 1: "Minimize the interface — aim for 1–3 entry points max. Maximise leverage per entry point."
- Agent 2: "Maximise flexibility — support many use cases and extension."
- Agent 3: "Optimise for the most common caller — make the default case trivial."
- Agent 4 (if applicable): "Design around ports & adapters for cross-seam dependencies."
Include both [LANGUAGE.md](LANGUAGE.md) vocabulary and CONTEXT.md vocabulary in the brief so each sub-agent names things consistently with the architecture language and the project's domain language.
Each sub-agent outputs:
1. Interface (types, methods, params — plus invariants, ordering, error modes)
2. Usage example showing how callers use it
3. What the implementation hides behind the seam
4. Dependency strategy and adapters (see [DEEPENING.md](DEEPENING.md))
5. Trade-offs — where leverage is high, where it's thin
### 3. Present and compare
Present designs sequentially so the user can absorb each one, then compare them in prose. Contrast by **depth** (leverage at the interface), **locality** (where change concentrates), and **seam placement**.
After comparing, give your own recommendation: which design you think is strongest and why. If elements from different designs would combine well, propose a hybrid. Be opinionated — the user wants a strong read, not a menu.

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# Language
Shared vocabulary for every suggestion this skill makes. Use these terms exactly — don't substitute "component," "service," "API," or "boundary." Consistent language is the whole point.
## Terms
**Module**
Anything with an interface and an implementation. Deliberately scale-agnostic — applies equally to a function, class, package, or tier-spanning slice.
_Avoid_: unit, component, service.
**Interface**
Everything a caller must know to use the module correctly. Includes the type signature, but also invariants, ordering constraints, error modes, required configuration, and performance characteristics.
_Avoid_: API, signature (too narrow — those refer only to the type-level surface).
**Implementation**
What's inside a module — its body of code. Distinct from **Adapter**: a thing can be a small adapter with a large implementation (a Postgres repo) or a large adapter with a small implementation (an in-memory fake). Reach for "adapter" when the seam is the topic; "implementation" otherwise.
**Depth**
Leverage at the interface — the amount of behaviour a caller (or test) can exercise per unit of interface they have to learn. A module is **deep** when a large amount of behaviour sits behind a small interface. A module is **shallow** when the interface is nearly as complex as the implementation.
**Seam** _(from Michael Feathers)_
A place where you can alter behaviour without editing in that place. The *location* at which a module's interface lives. Choosing where to put the seam is its own design decision, distinct from what goes behind it.
_Avoid_: boundary (overloaded with DDD's bounded context).
**Adapter**
A concrete thing that satisfies an interface at a seam. Describes *role* (what slot it fills), not substance (what's inside).
**Leverage**
What callers get from depth. More capability per unit of interface they have to learn. One implementation pays back across N call sites and M tests.
**Locality**
What maintainers get from depth. Change, bugs, knowledge, and verification concentrate at one place rather than spreading across callers. Fix once, fixed everywhere.
## Principles
- **Depth is a property of the interface, not the implementation.** A deep module can be internally composed of small, mockable, swappable parts — they just aren't part of the interface. A module can have **internal seams** (private to its implementation, used by its own tests) as well as the **external seam** at its interface.
- **The deletion test.** Imagine deleting the module. If complexity vanishes, the module wasn't hiding anything (it was a pass-through). If complexity reappears across N callers, the module was earning its keep.
- **The interface is the test surface.** Callers and tests cross the same seam. If you want to test *past* the interface, the module is probably the wrong shape.
- **One adapter means a hypothetical seam. Two adapters means a real one.** Don't introduce a seam unless something actually varies across it.
## Relationships
- A **Module** has exactly one **Interface** (the surface it presents to callers and tests).
- **Depth** is a property of a **Module**, measured against its **Interface**.
- A **Seam** is where a **Module**'s **Interface** lives.
- An **Adapter** sits at a **Seam** and satisfies the **Interface**.
- **Depth** produces **Leverage** for callers and **Locality** for maintainers.
## Rejected framings
- **Depth as ratio of implementation-lines to interface-lines** (Ousterhout): rewards padding the implementation. We use depth-as-leverage instead.
- **"Interface" as the TypeScript `interface` keyword or a class's public methods**: too narrow — interface here includes every fact a caller must know.
- **"Boundary"**: overloaded with DDD's bounded context. Say **seam** or **interface**.

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---
name: improve-codebase-architecture
description: Find deepening opportunities in a codebase, informed by the domain language in CONTEXT.md and the decisions in docs/adr/. Use when the user wants to improve architecture, find refactoring opportunities, consolidate tightly-coupled modules, or make a codebase more testable and AI-navigable.
---
# Improve Codebase Architecture
Surface architectural friction and propose **deepening opportunities** — refactors that turn shallow modules into deep ones. The aim is testability and AI-navigability.
## Glossary
Use these terms exactly in every suggestion. Consistent language is the point — don't drift into "component," "service," "API," or "boundary." Full definitions in [LANGUAGE.md](LANGUAGE.md).
- **Module** — anything with an interface and an implementation (function, class, package, slice).
- **Interface** — everything a caller must know to use the module: types, invariants, error modes, ordering, config. Not just the type signature.
- **Implementation** — the code inside.
- **Depth** — leverage at the interface: a lot of behaviour behind a small interface. **Deep** = high leverage. **Shallow** = interface nearly as complex as the implementation.
- **Seam** — where an interface lives; a place behaviour can be altered without editing in place. (Use this, not "boundary.")
- **Adapter** — a concrete thing satisfying an interface at a seam.
- **Leverage** — what callers get from depth.
- **Locality** — what maintainers get from depth: change, bugs, knowledge concentrated in one place.
Key principles (see [LANGUAGE.md](LANGUAGE.md) for the full list):
- **Deletion test**: imagine deleting the module. If complexity vanishes, it was a pass-through. If complexity reappears across N callers, it was earning its keep.
- **The interface is the test surface.**
- **One adapter = hypothetical seam. Two adapters = real seam.**
This skill is _informed_ by the project's domain model — `CONTEXT.md` and any `docs/adr/`. The domain language gives names to good seams; ADRs record decisions the skill should not re-litigate. See [CONTEXT-FORMAT.md](../domain-model/CONTEXT-FORMAT.md) and [ADR-FORMAT.md](../domain-model/ADR-FORMAT.md).
## Process
### 1. Explore
Read existing documentation first:
- `CONTEXT.md` (or `CONTEXT-MAP.md` + each `CONTEXT.md` in a multi-context repo)
- Relevant ADRs in `docs/adr/` (and any context-scoped `docs/adr/` directories)
If any of these files don't exist, proceed silently — don't flag their absence or suggest creating them upfront.
Then use the Agent tool with `subagent_type=Explore` to walk the codebase. Don't follow rigid heuristics — explore organically and note where you experience friction:
- Where does understanding one concept require bouncing between many small modules?
- Where are modules **shallow** — interface nearly as complex as the implementation?
- Where have pure functions been extracted just for testability, but the real bugs hide in how they're called (no **locality**)?
- Where do tightly-coupled modules leak across their seams?
- Which parts of the codebase are untested, or hard to test through their current interface?
Apply the **deletion test** to anything you suspect is shallow: would deleting it concentrate complexity, or just move it? A "yes, concentrates" is the signal you want.
### 2. Present candidates
Present a numbered list of deepening opportunities. For each candidate:
- **Files** — which files/modules are involved
- **Problem** — why the current architecture is causing friction
- **Solution** — plain English description of what would change
- **Benefits** — explained in terms of locality and leverage, and also in how tests would improve
**Use CONTEXT.md vocabulary for the domain, and [LANGUAGE.md](LANGUAGE.md) vocabulary for the architecture.** If `CONTEXT.md` defines "Order," talk about "the Order intake module" — not "the FooBarHandler," and not "the Order service."
**ADR conflicts**: if a candidate contradicts an existing ADR, only surface it when the friction is real enough to warrant revisiting the ADR. Mark it clearly (e.g. _"contradicts ADR-0007 — but worth reopening because…"_). Don't list every theoretical refactor an ADR forbids.
Do NOT propose interfaces yet. Ask the user: "Which of these would you like to explore?"
### 3. Grilling loop
Once the user picks a candidate, drop into a grilling conversation. Walk the design tree with them — constraints, dependencies, the shape of the deepened module, what sits behind the seam, what tests survive.
Side effects happen inline as decisions crystallize:
- **Naming a deepened module after a concept not in `CONTEXT.md`?** Add the term to `CONTEXT.md` — same discipline as `/domain-model` (see [CONTEXT-FORMAT.md](../domain-model/CONTEXT-FORMAT.md)). Create the file lazily if it doesn't exist.
- **Sharpening a fuzzy term during the conversation?** Update `CONTEXT.md` right there.
- **User rejects the candidate with a load-bearing reason?** Offer an ADR, framed as: _"Want me to record this as an ADR so future architecture reviews don't re-suggest it?"_ Only offer when the reason would actually be needed by a future explorer to avoid re-suggesting the same thing — skip ephemeral reasons ("not worth it right now") and self-evident ones. See [ADR-FORMAT.md](../domain-model/ADR-FORMAT.md).
- **Want to explore alternative interfaces for the deepened module?** See [INTERFACE-DESIGN.md](INTERFACE-DESIGN.md).

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---
name: migrate-to-shoehorn
description: Migrate test files from `as` type assertions to @total-typescript/shoehorn. Use when user mentions shoehorn, wants to replace `as` in tests, or needs partial test data.
---
# Migrate to Shoehorn
## Why shoehorn?
`shoehorn` lets you pass partial data in tests while keeping TypeScript happy. It replaces `as` assertions with type-safe alternatives.
**Test code only.** Never use shoehorn in production code.
Problems with `as` in tests:
- Trained not to use it
- Must manually specify target type
- Double-as (`as unknown as Type`) for intentionally wrong data
## Install
```bash
npm i @total-typescript/shoehorn
```
## Migration patterns
### Large objects with few needed properties
Before:
```ts
type Request = {
body: { id: string };
headers: Record<string, string>;
cookies: Record<string, string>;
// ...20 more properties
};
it("gets user by id", () => {
// Only care about body.id but must fake entire Request
getUser({
body: { id: "123" },
headers: {},
cookies: {},
// ...fake all 20 properties
});
});
```
After:
```ts
import { fromPartial } from "@total-typescript/shoehorn";
it("gets user by id", () => {
getUser(
fromPartial({
body: { id: "123" },
}),
);
});
```
### `as Type` → `fromPartial()`
Before:
```ts
getUser({ body: { id: "123" } } as Request);
```
After:
```ts
import { fromPartial } from "@total-typescript/shoehorn";
getUser(fromPartial({ body: { id: "123" } }));
```
### `as unknown as Type` → `fromAny()`
Before:
```ts
getUser({ body: { id: 123 } } as unknown as Request); // wrong type on purpose
```
After:
```ts
import { fromAny } from "@total-typescript/shoehorn";
getUser(fromAny({ body: { id: 123 } }));
```
## When to use each
| Function | Use case |
| --------------- | -------------------------------------------------- |
| `fromPartial()` | Pass partial data that still type-checks |
| `fromAny()` | Pass intentionally wrong data (keeps autocomplete) |
| `fromExact()` | Force full object (swap with fromPartial later) |
## Workflow
1. **Gather requirements** - ask user:
- What test files have `as` assertions causing problems?
- Are they dealing with large objects where only some properties matter?
- Do they need to pass intentionally wrong data for error testing?
2. **Install and migrate**:
- [ ] Install: `npm i @total-typescript/shoehorn`
- [ ] Find test files with `as` assertions: `grep -r " as [A-Z]" --include="*.test.ts" --include="*.spec.ts"`
- [ ] Replace `as Type` with `fromPartial()`
- [ ] Replace `as unknown as Type` with `fromAny()`
- [ ] Add imports from `@total-typescript/shoehorn`
- [ ] Run type check to verify

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---
name: obsidian-vault
description: Search, create, and manage notes in the Obsidian vault with wikilinks and index notes. Use when user wants to find, create, or organize notes in Obsidian.
---
# Obsidian Vault
## Vault location
`/mnt/d/Obsidian Vault/AI Research/`
Mostly flat at root level.
## Naming conventions
- **Index notes**: aggregate related topics (e.g., `Ralph Wiggum Index.md`, `Skills Index.md`, `RAG Index.md`)
- **Title case** for all note names
- No folders for organization - use links and index notes instead
## Linking
- Use Obsidian `[[wikilinks]]` syntax: `[[Note Title]]`
- Notes link to dependencies/related notes at the bottom
- Index notes are just lists of `[[wikilinks]]`
## Workflows
### Search for notes
```bash
# Search by filename
find "/mnt/d/Obsidian Vault/AI Research/" -name "*.md" | grep -i "keyword"
# Search by content
grep -rl "keyword" "/mnt/d/Obsidian Vault/AI Research/" --include="*.md"
```
Or use Grep/Glob tools directly on the vault path.
### Create a new note
1. Use **Title Case** for filename
2. Write content as a unit of learning (per vault rules)
3. Add `[[wikilinks]]` to related notes at the bottom
4. If part of a numbered sequence, use the hierarchical numbering scheme
### Find related notes
Search for `[[Note Title]]` across the vault to find backlinks:
```bash
grep -rl "\\[\\[Note Title\\]\\]" "/mnt/d/Obsidian Vault/AI Research/"
```
### Find index notes
```bash
find "/mnt/d/Obsidian Vault/AI Research/" -name "*Index*"
```

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---
name: qa
description: Interactive QA session where user reports bugs or issues conversationally, and the agent files GitHub issues. Explores the codebase in the background for context and domain language. Use when user wants to report bugs, do QA, file issues conversationally, or mentions "QA session".
---
# QA Session
Run an interactive QA session. The user describes problems they're encountering. You clarify, explore the codebase for context, and file GitHub issues that are durable, user-focused, and use the project's domain language.
## For each issue the user raises
### 1. Listen and lightly clarify
Let the user describe the problem in their own words. Ask **at most 2-3 short clarifying questions** focused on:
- What they expected vs what actually happened
- Steps to reproduce (if not obvious)
- Whether it's consistent or intermittent
Do NOT over-interview. If the description is clear enough to file, move on.
### 2. Explore the codebase in the background
While talking to the user, kick off an Agent (subagent_type=Explore) in the background to understand the relevant area. The goal is NOT to find a fix — it's to:
- Learn the domain language used in that area (check UBIQUITOUS_LANGUAGE.md)
- Understand what the feature is supposed to do
- Identify the user-facing behavior boundary
This context helps you write a better issue — but the issue itself should NOT reference specific files, line numbers, or internal implementation details.
### 3. Assess scope: single issue or breakdown?
Before filing, decide whether this is a **single issue** or needs to be **broken down** into multiple issues.
Break down when:
- The fix spans multiple independent areas (e.g. "the form validation is wrong AND the success message is missing AND the redirect is broken")
- There are clearly separable concerns that different people could work on in parallel
- The user describes something that has multiple distinct failure modes or symptoms
Keep as a single issue when:
- It's one behavior that's wrong in one place
- The symptoms are all caused by the same root behavior
### 4. File the GitHub issue(s)
Create issues with `gh issue create`. Do NOT ask the user to review first — just file and share URLs.
Issues must be **durable** — they should still make sense after major refactors. Write from the user's perspective.
#### For a single issue
Use this template:
```
## What happened
[Describe the actual behavior the user experienced, in plain language]
## What I expected
[Describe the expected behavior]
## Steps to reproduce
1. [Concrete, numbered steps a developer can follow]
2. [Use domain terms from the codebase, not internal module names]
3. [Include relevant inputs, flags, or configuration]
## Additional context
[Any extra observations from the user or from codebase exploration that help frame the issue — e.g. "this only happens when using the Docker layer, not the filesystem layer" — use domain language but don't cite files]
```
#### For a breakdown (multiple issues)
Create issues in dependency order (blockers first) so you can reference real issue numbers.
Use this template for each sub-issue:
```
## Parent issue
#<parent-issue-number> (if you created a tracking issue) or "Reported during QA session"
## What's wrong
[Describe this specific behavior problem — just this slice, not the whole report]
## What I expected
[Expected behavior for this specific slice]
## Steps to reproduce
1. [Steps specific to THIS issue]
## Blocked by
- #<issue-number> (if this issue can't be fixed until another is resolved)
Or "None — can start immediately" if no blockers.
## Additional context
[Any extra observations relevant to this slice]
```
When creating a breakdown:
- **Prefer many thin issues over few thick ones** — each should be independently fixable and verifiable
- **Mark blocking relationships honestly** — if issue B genuinely can't be tested until issue A is fixed, say so. If they're independent, mark both as "None — can start immediately"
- **Create issues in dependency order** so you can reference real issue numbers in "Blocked by"
- **Maximize parallelism** — the goal is that multiple people (or agents) can grab different issues simultaneously
#### Rules for all issue bodies
- **No file paths or line numbers** — these go stale
- **Use the project's domain language** (check UBIQUITOUS_LANGUAGE.md if it exists)
- **Describe behaviors, not code** — "the sync service fails to apply the patch" not "applyPatch() throws on line 42"
- **Reproduction steps are mandatory** — if you can't determine them, ask the user
- **Keep it concise** — a developer should be able to read the issue in 30 seconds
After filing, print all issue URLs (with blocking relationships summarized) and ask: "Next issue, or are we done?"
### 5. Continue the session
Keep going until the user says they're done. Each issue is independent — don't batch them.

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---
name: request-refactor-plan
description: Create a detailed refactor plan with tiny commits via user interview, then file it as a GitHub issue. Use when user wants to plan a refactor, create a refactoring RFC, or break a refactor into safe incremental steps.
---
This skill will be invoked when the user wants to create a refactor request. You should go through the steps below. You may skip steps if you don't consider them necessary.
1. Ask the user for a long, detailed description of the problem they want to solve and any potential ideas for solutions.
2. Explore the repo to verify their assertions and understand the current state of the codebase.
3. Ask whether they have considered other options, and present other options to them.
4. Interview the user about the implementation. Be extremely detailed and thorough.
5. Hammer out the exact scope of the implementation. Work out what you plan to change and what you plan not to change.
6. Look in the codebase to check for test coverage of this area of the codebase. If there is insufficient test coverage, ask the user what their plans for testing are.
7. Break the implementation into a plan of tiny commits. Remember Martin Fowler's advice to "make each refactoring step as small as possible, so that you can always see the program working."
8. Create a GitHub issue with the refactor plan. Use the following template for the issue description:
<refactor-plan-template>
## Problem Statement
The problem that the developer is facing, from the developer's perspective.
## Solution
The solution to the problem, from the developer's perspective.
## Commits
A LONG, detailed implementation plan. Write the plan in plain English, breaking down the implementation into the tiniest commits possible. Each commit should leave the codebase in a working state.
## Decision Document
A list of implementation decisions that were made. This can include:
- The modules that will be built/modified
- The interfaces of those modules that will be modified
- Technical clarifications from the developer
- Architectural decisions
- Schema changes
- API contracts
- Specific interactions
Do NOT include specific file paths or code snippets. They may end up being outdated very quickly.
## Testing Decisions
A list of testing decisions that were made. Include:
- A description of what makes a good test (only test external behavior, not implementation details)
- Which modules will be tested
- Prior art for the tests (i.e. similar types of tests in the codebase)
## Out of Scope
A description of the things that are out of scope for this refactor.
## Further Notes (optional)
Any further notes about the refactor.
</refactor-plan-template>

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---
name: scaffold-exercises
description: Create exercise directory structures with sections, problems, solutions, and explainers that pass linting. Use when user wants to scaffold exercises, create exercise stubs, or set up a new course section.
---
# Scaffold Exercises
Create exercise directory structures that pass `pnpm ai-hero-cli internal lint`, then commit with `git commit`.
## Directory naming
- **Sections**: `XX-section-name/` inside `exercises/` (e.g., `01-retrieval-skill-building`)
- **Exercises**: `XX.YY-exercise-name/` inside a section (e.g., `01.03-retrieval-with-bm25`)
- Section number = `XX`, exercise number = `XX.YY`
- Names are dash-case (lowercase, hyphens)
## Exercise variants
Each exercise needs at least one of these subfolders:
- `problem/` - student workspace with TODOs
- `solution/` - reference implementation
- `explainer/` - conceptual material, no TODOs
When stubbing, default to `explainer/` unless the plan specifies otherwise.
## Required files
Each subfolder (`problem/`, `solution/`, `explainer/`) needs a `readme.md` that:
- Is **not empty** (must have real content, even a single title line works)
- Has no broken links
When stubbing, create a minimal readme with a title and a description:
```md
# Exercise Title
Description here
```
If the subfolder has code, it also needs a `main.ts` (>1 line). But for stubs, a readme-only exercise is fine.
## Workflow
1. **Parse the plan** - extract section names, exercise names, and variant types
2. **Create directories** - `mkdir -p` for each path
3. **Create stub readmes** - one `readme.md` per variant folder with a title
4. **Run lint** - `pnpm ai-hero-cli internal lint` to validate
5. **Fix any errors** - iterate until lint passes
## Lint rules summary
The linter (`pnpm ai-hero-cli internal lint`) checks:
- Each exercise has subfolders (`problem/`, `solution/`, `explainer/`)
- At least one of `problem/`, `explainer/`, or `explainer.1/` exists
- `readme.md` exists and is non-empty in the primary subfolder
- No `.gitkeep` files
- No `speaker-notes.md` files
- No broken links in readmes
- No `pnpm run exercise` commands in readmes
- `main.ts` required per subfolder unless it's readme-only
## Moving/renaming exercises
When renumbering or moving exercises:
1. Use `git mv` (not `mv`) to rename directories - preserves git history
2. Update the numeric prefix to maintain order
3. Re-run lint after moves
Example:
```bash
git mv exercises/01-retrieval/01.03-embeddings exercises/01-retrieval/01.04-embeddings
```
## Example: stubbing from a plan
Given a plan like:
```
Section 05: Memory Skill Building
- 05.01 Introduction to Memory
- 05.02 Short-term Memory (explainer + problem + solution)
- 05.03 Long-term Memory
```
Create:
```bash
mkdir -p exercises/05-memory-skill-building/05.01-introduction-to-memory/explainer
mkdir -p exercises/05-memory-skill-building/05.02-short-term-memory/{explainer,problem,solution}
mkdir -p exercises/05-memory-skill-building/05.03-long-term-memory/explainer
```
Then create readme stubs:
```
exercises/05-memory-skill-building/05.01-introduction-to-memory/explainer/readme.md -> "# Introduction to Memory"
exercises/05-memory-skill-building/05.02-short-term-memory/explainer/readme.md -> "# Short-term Memory"
exercises/05-memory-skill-building/05.02-short-term-memory/problem/readme.md -> "# Short-term Memory"
exercises/05-memory-skill-building/05.02-short-term-memory/solution/readme.md -> "# Short-term Memory"
exercises/05-memory-skill-building/05.03-long-term-memory/explainer/readme.md -> "# Long-term Memory"
```

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---
name: setup-pre-commit
description: Set up Husky pre-commit hooks with lint-staged (Prettier), type checking, and tests in the current repo. Use when user wants to add pre-commit hooks, set up Husky, configure lint-staged, or add commit-time formatting/typechecking/testing.
---
# Setup Pre-Commit Hooks
## What This Sets Up
- **Husky** pre-commit hook
- **lint-staged** running Prettier on all staged files
- **Prettier** config (if missing)
- **typecheck** and **test** scripts in the pre-commit hook
## Steps
### 1. Detect package manager
Check for `package-lock.json` (npm), `pnpm-lock.yaml` (pnpm), `yarn.lock` (yarn), `bun.lockb` (bun). Use whichever is present. Default to npm if unclear.
### 2. Install dependencies
Install as devDependencies:
```
husky lint-staged prettier
```
### 3. Initialize Husky
```bash
npx husky init
```
This creates `.husky/` dir and adds `prepare: "husky"` to package.json.
### 4. Create `.husky/pre-commit`
Write this file (no shebang needed for Husky v9+):
```
npx lint-staged
npm run typecheck
npm run test
```
**Adapt**: Replace `npm` with detected package manager. If repo has no `typecheck` or `test` script in package.json, omit those lines and tell the user.
### 5. Create `.lintstagedrc`
```json
{
"*": "prettier --ignore-unknown --write"
}
```
### 6. Create `.prettierrc` (if missing)
Only create if no Prettier config exists. Use these defaults:
```json
{
"useTabs": false,
"tabWidth": 2,
"printWidth": 80,
"singleQuote": false,
"trailingComma": "es5",
"semi": true,
"arrowParens": "always"
}
```
### 7. Verify
- [ ] `.husky/pre-commit` exists and is executable
- [ ] `.lintstagedrc` exists
- [ ] `prepare` script in package.json is `"husky"`
- [ ] `prettier` config exists
- [ ] Run `npx lint-staged` to verify it works
### 8. Commit
Stage all changed/created files and commit with message: `Add pre-commit hooks (husky + lint-staged + prettier)`
This will run through the new pre-commit hooks — a good smoke test that everything works.
## Notes
- Husky v9+ doesn't need shebangs in hook files
- `prettier --ignore-unknown` skips files Prettier can't parse (images, etc.)
- The pre-commit runs lint-staged first (fast, staged-only), then full typecheck and tests

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---
name: tdd
description: Test-driven development with red-green-refactor loop. Use when user wants to build features or fix bugs using TDD, mentions "red-green-refactor", wants integration tests, or asks for test-first development.
---
# Test-Driven Development
## Philosophy
**Core principle**: Tests should verify behavior through public interfaces, not implementation details. Code can change entirely; tests shouldn't.
**Good tests** are integration-style: they exercise real code paths through public APIs. They describe _what_ the system does, not _how_ it does it. A good test reads like a specification - "user can checkout with valid cart" tells you exactly what capability exists. These tests survive refactors because they don't care about internal structure.
**Bad tests** are coupled to implementation. They mock internal collaborators, test private methods, or verify through external means (like querying a database directly instead of using the interface). The warning sign: your test breaks when you refactor, but behavior hasn't changed. If you rename an internal function and tests fail, those tests were testing implementation, not behavior.
See [tests.md](tests.md) for examples and [mocking.md](mocking.md) for mocking guidelines.
## Anti-Pattern: Horizontal Slices
**DO NOT write all tests first, then all implementation.** This is "horizontal slicing" - treating RED as "write all tests" and GREEN as "write all code."
This produces **crap tests**:
- Tests written in bulk test _imagined_ behavior, not _actual_ behavior
- You end up testing the _shape_ of things (data structures, function signatures) rather than user-facing behavior
- Tests become insensitive to real changes - they pass when behavior breaks, fail when behavior is fine
- You outrun your headlights, committing to test structure before understanding the implementation
**Correct approach**: Vertical slices via tracer bullets. One test → one implementation → repeat. Each test responds to what you learned from the previous cycle. Because you just wrote the code, you know exactly what behavior matters and how to verify it.
```
WRONG (horizontal):
RED: test1, test2, test3, test4, test5
GREEN: impl1, impl2, impl3, impl4, impl5
RIGHT (vertical):
RED→GREEN: test1→impl1
RED→GREEN: test2→impl2
RED→GREEN: test3→impl3
...
```
## Workflow
### 1. Planning
Before writing any code:
- [ ] Confirm with user what interface changes are needed
- [ ] Confirm with user which behaviors to test (prioritize)
- [ ] Identify opportunities for [deep modules](deep-modules.md) (small interface, deep implementation)
- [ ] Design interfaces for [testability](interface-design.md)
- [ ] List the behaviors to test (not implementation steps)
- [ ] Get user approval on the plan
Ask: "What should the public interface look like? Which behaviors are most important to test?"
**You can't test everything.** Confirm with the user exactly which behaviors matter most. Focus testing effort on critical paths and complex logic, not every possible edge case.
### 2. Tracer Bullet
Write ONE test that confirms ONE thing about the system:
```
RED: Write test for first behavior → test fails
GREEN: Write minimal code to pass → test passes
```
This is your tracer bullet - proves the path works end-to-end.
### 3. Incremental Loop
For each remaining behavior:
```
RED: Write next test → fails
GREEN: Minimal code to pass → passes
```
Rules:
- One test at a time
- Only enough code to pass current test
- Don't anticipate future tests
- Keep tests focused on observable behavior
### 4. Refactor
After all tests pass, look for [refactor candidates](refactoring.md):
- [ ] Extract duplication
- [ ] Deepen modules (move complexity behind simple interfaces)
- [ ] Apply SOLID principles where natural
- [ ] Consider what new code reveals about existing code
- [ ] Run tests after each refactor step
**Never refactor while RED.** Get to GREEN first.
## Checklist Per Cycle
```
[ ] Test describes behavior, not implementation
[ ] Test uses public interface only
[ ] Test would survive internal refactor
[ ] Code is minimal for this test
[ ] No speculative features added
```

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# Deep Modules
From "A Philosophy of Software Design":
**Deep module** = small interface + lots of implementation
```
┌─────────────────────┐
│ Small Interface │ ← Few methods, simple params
├─────────────────────┤
│ │
│ │
│ Deep Implementation│ ← Complex logic hidden
│ │
│ │
└─────────────────────┘
```
**Shallow module** = large interface + little implementation (avoid)
```
┌─────────────────────────────────┐
│ Large Interface │ ← Many methods, complex params
├─────────────────────────────────┤
│ Thin Implementation │ ← Just passes through
└─────────────────────────────────┘
```
When designing interfaces, ask:
- Can I reduce the number of methods?
- Can I simplify the parameters?
- Can I hide more complexity inside?

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# Interface Design for Testability
Good interfaces make testing natural:
1. **Accept dependencies, don't create them**
```typescript
// Testable
function processOrder(order, paymentGateway) {}
// Hard to test
function processOrder(order) {
const gateway = new StripeGateway();
}
```
2. **Return results, don't produce side effects**
```typescript
// Testable
function calculateDiscount(cart): Discount {}
// Hard to test
function applyDiscount(cart): void {
cart.total -= discount;
}
```
3. **Small surface area**
- Fewer methods = fewer tests needed
- Fewer params = simpler test setup

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# When to Mock
Mock at **system boundaries** only:
- External APIs (payment, email, etc.)
- Databases (sometimes - prefer test DB)
- Time/randomness
- File system (sometimes)
Don't mock:
- Your own classes/modules
- Internal collaborators
- Anything you control
## Designing for Mockability
At system boundaries, design interfaces that are easy to mock:
**1. Use dependency injection**
Pass external dependencies in rather than creating them internally:
```typescript
// Easy to mock
function processPayment(order, paymentClient) {
return paymentClient.charge(order.total);
}
// Hard to mock
function processPayment(order) {
const client = new StripeClient(process.env.STRIPE_KEY);
return client.charge(order.total);
}
```
**2. Prefer SDK-style interfaces over generic fetchers**
Create specific functions for each external operation instead of one generic function with conditional logic:
```typescript
// GOOD: Each function is independently mockable
const api = {
getUser: (id) => fetch(`/users/${id}`),
getOrders: (userId) => fetch(`/users/${userId}/orders`),
createOrder: (data) => fetch('/orders', { method: 'POST', body: data }),
};
// BAD: Mocking requires conditional logic inside the mock
const api = {
fetch: (endpoint, options) => fetch(endpoint, options),
};
```
The SDK approach means:
- Each mock returns one specific shape
- No conditional logic in test setup
- Easier to see which endpoints a test exercises
- Type safety per endpoint

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# Refactor Candidates
After TDD cycle, look for:
- **Duplication** → Extract function/class
- **Long methods** → Break into private helpers (keep tests on public interface)
- **Shallow modules** → Combine or deepen
- **Feature envy** → Move logic to where data lives
- **Primitive obsession** → Introduce value objects
- **Existing code** the new code reveals as problematic

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# Good and Bad Tests
## Good Tests
**Integration-style**: Test through real interfaces, not mocks of internal parts.
```typescript
// GOOD: Tests observable behavior
test("user can checkout with valid cart", async () => {
const cart = createCart();
cart.add(product);
const result = await checkout(cart, paymentMethod);
expect(result.status).toBe("confirmed");
});
```
Characteristics:
- Tests behavior users/callers care about
- Uses public API only
- Survives internal refactors
- Describes WHAT, not HOW
- One logical assertion per test
## Bad Tests
**Implementation-detail tests**: Coupled to internal structure.
```typescript
// BAD: Tests implementation details
test("checkout calls paymentService.process", async () => {
const mockPayment = jest.mock(paymentService);
await checkout(cart, payment);
expect(mockPayment.process).toHaveBeenCalledWith(cart.total);
});
```
Red flags:
- Mocking internal collaborators
- Testing private methods
- Asserting on call counts/order
- Test breaks when refactoring without behavior change
- Test name describes HOW not WHAT
- Verifying through external means instead of interface
```typescript
// BAD: Bypasses interface to verify
test("createUser saves to database", async () => {
await createUser({ name: "Alice" });
const row = await db.query("SELECT * FROM users WHERE name = ?", ["Alice"]);
expect(row).toBeDefined();
});
// GOOD: Verifies through interface
test("createUser makes user retrievable", async () => {
const user = await createUser({ name: "Alice" });
const retrieved = await getUser(user.id);
expect(retrieved.name).toBe("Alice");
});
```

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---
name: to-issues
description: Break a plan, spec, or PRD into independently-grabbable GitHub issues using tracer-bullet vertical slices. Use when user wants to convert a plan into issues, create implementation tickets, or break down work into issues.
---
# To Issues
Break a plan into independently-grabbable GitHub issues using vertical slices (tracer bullets).
## Process
### 1. Gather context
Work from whatever is already in the conversation context. If the user passes a GitHub issue number or URL as an argument, fetch it with `gh issue view <number>` (with comments).
### 2. Explore the codebase (optional)
If you have not already explored the codebase, do so to understand the current state of the code.
### 3. Draft vertical slices
Break the plan into **tracer bullet** issues. Each issue is a thin vertical slice that cuts through ALL integration layers end-to-end, NOT a horizontal slice of one layer.
Slices may be 'HITL' or 'AFK'. HITL slices require human interaction, such as an architectural decision or a design review. AFK slices can be implemented and merged without human interaction. Prefer AFK over HITL where possible.
<vertical-slice-rules>
- Each slice delivers a narrow but COMPLETE path through every layer (schema, API, UI, tests)
- A completed slice is demoable or verifiable on its own
- Prefer many thin slices over few thick ones
</vertical-slice-rules>
### 4. Quiz the user
Present the proposed breakdown as a numbered list. For each slice, show:
- **Title**: short descriptive name
- **Type**: HITL / AFK
- **Blocked by**: which other slices (if any) must complete first
- **User stories covered**: which user stories this addresses (if the source material has them)
Ask the user:
- Does the granularity feel right? (too coarse / too fine)
- Are the dependency relationships correct?
- Should any slices be merged or split further?
- Are the correct slices marked as HITL and AFK?
Iterate until the user approves the breakdown.
### 5. Create the GitHub issues
For each approved slice, create a GitHub issue using `gh issue create`. Use the issue body template below.
Create issues in dependency order (blockers first) so you can reference real issue numbers in the "Blocked by" field.
<issue-template>
## Parent
#<parent-issue-number> (if the source was a GitHub issue, otherwise omit this section)
## What to build
A concise description of this vertical slice. Describe the end-to-end behavior, not layer-by-layer implementation.
## Acceptance criteria
- [ ] Criterion 1
- [ ] Criterion 2
- [ ] Criterion 3
## Blocked by
- Blocked by #<issue-number> (if any)
Or "None - can start immediately" if no blockers.
</issue-template>
Do NOT close or modify any parent issue.

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---
name: to-prd
description: Turn the current conversation context into a PRD and submit it as a GitHub issue. Use when user wants to create a PRD from the current context.
---
This skill takes the current conversation context and codebase understanding and produces a PRD. Do NOT interview the user — just synthesize what you already know.
## Process
1. Explore the repo to understand the current state of the codebase, if you haven't already.
2. Sketch out the major modules you will need to build or modify to complete the implementation. Actively look for opportunities to extract deep modules that can be tested in isolation.
A deep module (as opposed to a shallow module) is one which encapsulates a lot of functionality in a simple, testable interface which rarely changes.
Check with the user that these modules match their expectations. Check with the user which modules they want tests written for.
3. Write the PRD using the template below and submit it as a GitHub issue.
<prd-template>
## Problem Statement
The problem that the user is facing, from the user's perspective.
## Solution
The solution to the problem, from the user's perspective.
## User Stories
A LONG, numbered list of user stories. Each user story should be in the format of:
1. As an <actor>, I want a <feature>, so that <benefit>
<user-story-example>
1. As a mobile bank customer, I want to see balance on my accounts, so that I can make better informed decisions about my spending
</user-story-example>
This list of user stories should be extremely extensive and cover all aspects of the feature.
## Implementation Decisions
A list of implementation decisions that were made. This can include:
- The modules that will be built/modified
- The interfaces of those modules that will be modified
- Technical clarifications from the developer
- Architectural decisions
- Schema changes
- API contracts
- Specific interactions
Do NOT include specific file paths or code snippets. They may end up being outdated very quickly.
## Testing Decisions
A list of testing decisions that were made. Include:
- A description of what makes a good test (only test external behavior, not implementation details)
- Which modules will be tested
- Prior art for the tests (i.e. similar types of tests in the codebase)
## Out of Scope
A description of the things that are out of scope for this PRD.
## Further Notes
Any further notes about the feature.
</prd-template>

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---
name: triage-issue
description: Triage a bug or issue by exploring the codebase to find root cause, then create a GitHub issue with a TDD-based fix plan. Use when user reports a bug, wants to file an issue, mentions "triage", or wants to investigate and plan a fix for a problem.
---
# Triage Issue
Investigate a reported problem, find its root cause, and create a GitHub issue with a TDD fix plan. This is a mostly hands-off workflow - minimize questions to the user.
## Process
### 1. Capture the problem
Get a brief description of the issue from the user. If they haven't provided one, ask ONE question: "What's the problem you're seeing?"
Do NOT ask follow-up questions yet. Start investigating immediately.
### 2. Explore and diagnose
Use the Agent tool with subagent_type=Explore to deeply investigate the codebase. Your goal is to find:
- **Where** the bug manifests (entry points, UI, API responses)
- **What** code path is involved (trace the flow)
- **Why** it fails (the root cause, not just the symptom)
- **What** related code exists (similar patterns, tests, adjacent modules)
Look at:
- Related source files and their dependencies
- Existing tests (what's tested, what's missing)
- Recent changes to affected files (`git log` on relevant files)
- Error handling in the code path
- Similar patterns elsewhere in the codebase that work correctly
### 3. Identify the fix approach
Based on your investigation, determine:
- The minimal change needed to fix the root cause
- Which modules/interfaces are affected
- What behaviors need to be verified via tests
- Whether this is a regression, missing feature, or design flaw
### 4. Design TDD fix plan
Create a concrete, ordered list of RED-GREEN cycles. Each cycle is one vertical slice:
- **RED**: Describe a specific test that captures the broken/missing behavior
- **GREEN**: Describe the minimal code change to make that test pass
Rules:
- Tests verify behavior through public interfaces, not implementation details
- One test at a time, vertical slices (NOT all tests first, then all code)
- Each test should survive internal refactors
- Include a final refactor step if needed
- **Durability**: Only suggest fixes that would survive radical codebase changes. Describe behaviors and contracts, not internal structure. Tests assert on observable outcomes (API responses, UI state, user-visible effects), not internal state. A good suggestion reads like a spec; a bad one reads like a diff.
### 5. Create the GitHub issue
Create a GitHub issue using `gh issue create` with the template below. Do NOT ask the user to review before creating - just create it and share the URL.
<issue-template>
## Problem
A clear description of the bug or issue, including:
- What happens (actual behavior)
- What should happen (expected behavior)
- How to reproduce (if applicable)
## Root Cause Analysis
Describe what you found during investigation:
- The code path involved
- Why the current code fails
- Any contributing factors
Do NOT include specific file paths, line numbers, or implementation details that couple to current code layout. Describe modules, behaviors, and contracts instead. The issue should remain useful even after major refactors.
## TDD Fix Plan
A numbered list of RED-GREEN cycles:
1. **RED**: Write a test that [describes expected behavior]
**GREEN**: [Minimal change to make it pass]
2. **RED**: Write a test that [describes next behavior]
**GREEN**: [Minimal change to make it pass]
...
**REFACTOR**: [Any cleanup needed after all tests pass]
## Acceptance Criteria
- [ ] Criterion 1
- [ ] Criterion 2
- [ ] All new tests pass
- [ ] Existing tests still pass
</issue-template>
After creating the issue, print the issue URL and a one-line summary of the root cause.

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---
name: ubiquitous-language
description: Extract a DDD-style ubiquitous language glossary from the current conversation, flagging ambiguities and proposing canonical terms. Saves to UBIQUITOUS_LANGUAGE.md. Use when user wants to define domain terms, build a glossary, harden terminology, create a ubiquitous language, or mentions "domain model" or "DDD".
disable-model-invocation: true
---
# Ubiquitous Language
Extract and formalize domain terminology from the current conversation into a consistent glossary, saved to a local file.
## Process
1. **Scan the conversation** for domain-relevant nouns, verbs, and concepts
2. **Identify problems**:
- Same word used for different concepts (ambiguity)
- Different words used for the same concept (synonyms)
- Vague or overloaded terms
3. **Propose a canonical glossary** with opinionated term choices
4. **Write to `UBIQUITOUS_LANGUAGE.md`** in the working directory using the format below
5. **Output a summary** inline in the conversation
## Output Format
Write a `UBIQUITOUS_LANGUAGE.md` file with this structure:
```md
# Ubiquitous Language
## Order lifecycle
| Term | Definition | Aliases to avoid |
| ----------- | ------------------------------------------------------- | --------------------- |
| **Order** | A customer's request to purchase one or more items | Purchase, transaction |
| **Invoice** | A request for payment sent to a customer after delivery | Bill, payment request |
## People
| Term | Definition | Aliases to avoid |
| ------------ | ------------------------------------------- | ---------------------- |
| **Customer** | A person or organization that places orders | Client, buyer, account |
| **User** | An authentication identity in the system | Login, account |
## Relationships
- An **Invoice** belongs to exactly one **Customer**
- An **Order** produces one or more **Invoices**
## Example dialogue
> **Dev:** "When a **Customer** places an **Order**, do we create the **Invoice** immediately?"
> **Domain expert:** "No — an **Invoice** is only generated once a **Fulfillment** is confirmed. A single **Order** can produce multiple **Invoices** if items ship in separate **Shipments**."
> **Dev:** "So if a **Shipment** is cancelled before dispatch, no **Invoice** exists for it?"
> **Domain expert:** "Exactly. The **Invoice** lifecycle is tied to the **Fulfillment**, not the **Order**."
## Flagged ambiguities
- "account" was used to mean both **Customer** and **User** — these are distinct concepts: a **Customer** places orders, while a **User** is an authentication identity that may or may not represent a **Customer**.
```
## Rules
- **Be opinionated.** When multiple words exist for the same concept, pick the best one and list the others as aliases to avoid.
- **Flag conflicts explicitly.** If a term is used ambiguously in the conversation, call it out in the "Flagged ambiguities" section with a clear recommendation.
- **Only include terms relevant for domain experts.** Skip the names of modules or classes unless they have meaning in the domain language.
- **Keep definitions tight.** One sentence max. Define what it IS, not what it does.
- **Show relationships.** Use bold term names and express cardinality where obvious.
- **Only include domain terms.** Skip generic programming concepts (array, function, endpoint) unless they have domain-specific meaning.
- **Group terms into multiple tables** when natural clusters emerge (e.g. by subdomain, lifecycle, or actor). Each group gets its own heading and table. If all terms belong to a single cohesive domain, one table is fine — don't force groupings.
- **Write an example dialogue.** A short conversation (3-5 exchanges) between a dev and a domain expert that demonstrates how the terms interact naturally. The dialogue should clarify boundaries between related concepts and show terms being used precisely.
<example>
## Example dialogue
> **Dev:** "How do I test the **sync service** without Docker?"
> **Domain expert:** "Provide the **filesystem layer** instead of the **Docker layer**. It implements the same **Sandbox service** interface but uses a local directory as the **sandbox**."
> **Dev:** "So **sync-in** still creates a **bundle** and unpacks it?"
> **Domain expert:** "Exactly. The **sync service** doesn't know which layer it's talking to. It calls `exec` and `copyIn` — the **filesystem layer** just runs those as local shell commands."
</example>
## Re-running
When invoked again in the same conversation:
1. Read the existing `UBIQUITOUS_LANGUAGE.md`
2. Incorporate any new terms from subsequent discussion
3. Update definitions if understanding has evolved
4. Re-flag any new ambiguities
5. Rewrite the example dialogue to incorporate new terms

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---
name: write-a-skill
description: Create new agent skills with proper structure, progressive disclosure, and bundled resources. Use when user wants to create, write, or build a new skill.
---
# Writing Skills
## Process
1. **Gather requirements** - ask user about:
- What task/domain does the skill cover?
- What specific use cases should it handle?
- Does it need executable scripts or just instructions?
- Any reference materials to include?
2. **Draft the skill** - create:
- SKILL.md with concise instructions
- Additional reference files if content exceeds 500 lines
- Utility scripts if deterministic operations needed
3. **Review with user** - present draft and ask:
- Does this cover your use cases?
- Anything missing or unclear?
- Should any section be more/less detailed?
## Skill Structure
```
skill-name/
├── SKILL.md # Main instructions (required)
├── REFERENCE.md # Detailed docs (if needed)
├── EXAMPLES.md # Usage examples (if needed)
└── scripts/ # Utility scripts (if needed)
└── helper.js
```
## SKILL.md Template
```md
---
name: skill-name
description: Brief description of capability. Use when [specific triggers].
---
# Skill Name
## Quick start
[Minimal working example]
## Workflows
[Step-by-step processes with checklists for complex tasks]
## Advanced features
[Link to separate files: See [REFERENCE.md](REFERENCE.md)]
```
## Description Requirements
The description is **the only thing your agent sees** when deciding which skill to load. It's surfaced in the system prompt alongside all other installed skills. Your agent reads these descriptions and picks the relevant skill based on the user's request.
**Goal**: Give your agent just enough info to know:
1. What capability this skill provides
2. When/why to trigger it (specific keywords, contexts, file types)
**Format**:
- Max 1024 chars
- Write in third person
- First sentence: what it does
- Second sentence: "Use when [specific triggers]"
**Good example**:
```
Extract text and tables from PDF files, fill forms, merge documents. Use when working with PDF files or when user mentions PDFs, forms, or document extraction.
```
**Bad example**:
```
Helps with documents.
```
The bad example gives your agent no way to distinguish this from other document skills.
## When to Add Scripts
Add utility scripts when:
- Operation is deterministic (validation, formatting)
- Same code would be generated repeatedly
- Errors need explicit handling
Scripts save tokens and improve reliability vs generated code.
## When to Split Files
Split into separate files when:
- SKILL.md exceeds 100 lines
- Content has distinct domains (finance vs sales schemas)
- Advanced features are rarely needed
## Review Checklist
After drafting, verify:
- [ ] Description includes triggers ("Use when...")
- [ ] SKILL.md under 100 lines
- [ ] No time-sensitive info
- [ ] Consistent terminology
- [ ] Concrete examples included
- [ ] References one level deep

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---
name: zoom-out
description: Tell the agent to zoom out and give broader context or a higher-level perspective. Use when you're unfamiliar with a section of code or need to understand how it fits into the bigger picture.
disable-model-invocation: true
---
I don't know this area of code well. Go up a layer of abstraction. Give me a map of all the relevant modules and callers.