ToTickets

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---
name: codebase-design
description: Shared vocabulary for designing deep modules. Use when the user wants to design or improve a module's interface, find deepening opportunities, decide where a seam goes, make code more testable or AI-navigable, or when another skill needs the deep-module vocabulary.
disable-model-invocation: true
---

# Codebase Design

Design **deep modules**: a lot of behaviour behind a small interface, placed at a clean seam, testable through that interface. Use this language and these principles wherever code is being designed or restructured. The aim is leverage for callers, locality for maintainers, and testability for everyone.

## Glossary

Use these terms exactly: don't substitute "component," "service," "API," or "boundary." Consistent language is the whole point.

**Module**: anything with an interface and an implementation. Deliberately scale-agnostic: a function, class, package, or tier-spanning slice. _Avoid_: unit, component, service.

**Interface**: everything a caller must know to use the module correctly: the type signature, but also invariants, ordering constraints, error modes, required configuration, and performance characteristics. _Avoid_: API, signature (too narrow, they 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, **shallow** when the interface is nearly as complex as the implementation.

**Seam** _(Michael Feathers)_: a place where you can alter behaviour without editing in that place; the *location* at which a module's interface lives. 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 learn. One implementation pays back across N call sites and M tests.

**Locality**: what maintainers get from depth. Change, bugs, knowledge, and verification concentrate in one place rather than spreading across callers. Fix once, fixed everywhere.

## Deep vs shallow

**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 an interface, ask:

- Can I reduce the number of methods?
- Can I simplify the parameters?
- Can I hide more complexity inside?

## 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, it was a pass-through. If complexity reappears across N callers, it 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.

## Designing 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.

## 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**.

## Going deeper

- **Deepening a cluster given its dependencies**, see [DEEPENING.md](DEEPENING.md): dependency categories, seam discipline, and replace-don't-layer testing.
- **Exploring alternative interfaces**, see [DESIGN-IT-TWICE.md](DESIGN-IT-TWICE.md): spin up parallel sub-agents to design the interface several radically different ways, then compare on depth, locality, and seam placement.

Referenced files: 3

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---
name: domain-modeling
description: Build and sharpen a project's domain model. Use when discussing codebase terminology, writing or editing a CONTEXT.md, or recording or editing an ADR.
disable-model-invocation: true
---

# Domain Modeling

Actively build and sharpen the project's domain model as you design. This is the *active* discipline: challenging terms, inventing edge-case scenarios, and writing the glossary and decisions down the moment they crystallise. (Merely *reading* `CONTEXT.md` for vocabulary is not this skill: that's a one-line habit any skill can do. This skill is for when you're changing the model, not just consuming it.)

## 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).

`CONTEXT.md` should be totally devoid of implementation details. Do not treat `CONTEXT.md` as a spec, a scratch pad, or a repository for implementation decisions. It is a glossary and nothing else.

### 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).

Referenced files: 3

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---
name: entry-to-tickets
description: "Use whenever the ToTickets plugin is selected. Route the request to the intended bundled workflow while keeping all dependencies internal to this plugin."
---

# ToTickets

This is the public entry workflow for this plugin. The bundled skills below are dependencies, not competing entry points.

## Mandatory routing

Invoke to-tickets. Preserve its vertical-slice and blocking-edge rules. Use bundled domain and codebase references as needed and setup only when tracker conventions are missing.

If a bundled workflow calls another bundled skill, invoke that local bundled copy. Never require the user to install another plugin to complete this workflow.

## Bundled workflows

- `to-tickets`
- `domain-modeling`
- `codebase-design`
- `setup-matt-pocock-skills`

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---
name: setup-matt-pocock-skills
description: "Configure this repo for the engineering skills: set up its issue tracker, triage label vocabulary, and domain doc layout. Run once before first use of the other engineering skills."
disable-model-invocation: true
---

# Setup Matt Pocock's Skills

Scaffold the per-repo configuration that the engineering skills assume:

- **Issue tracker**: where issues live (GitHub by default; local markdown is also supported out of the box)
- **Triage labels**: the strings used for the five canonical triage roles
- **Domain docs**: where `CONTEXT.md` and ADRs live, and the consumer rules for reading them

This is a prompt-driven skill, not a deterministic script. Explore, present what you found, confirm with the user, then write.

## Process

### 1. Explore

Look at the current repo to understand its starting state. Read whatever exists; don't assume:

- `git remote -v` and `.git/config`: is this a GitHub repo? Which one?
- `AGENTS.md` and `CLAUDE.md` at the repo root: does either exist? Is there already an `## Agent skills` section in either?
- `CONTEXT.md` and `CONTEXT-MAP.md` at the repo root
- `docs/adr/` and any `src/*/docs/adr/` directories
- `docs/agents/`: does this skill's prior output already exist?
- `.scratch/`: a sign that a local-markdown issue tracker convention is already in use
- Is the `triage` skill installed? (a `triage` skill folder alongside this one, or `triage` in your available skills.) This decides whether Section B runs at all.
- Monorepo signals: a `pnpm-workspace.yaml`, a `workspaces` field in `package.json`, or a populated `packages/*` with its own `src/`. These are present only in a genuinely large multi-package repo; their absence means single-context, which is almost every repo.

### 2. Present findings and ask

Summarise what's present and what's missing. Then take the sections in order. One section, one answer, then the next.

Lead each section with the recommended answer so the user can accept it in a word. Give a one-line explainer only when the choice genuinely branches; skip the section entirely when exploration already settled it (Section B when `triage` isn't installed, Section C when there's no monorepo).

**Section A: Issue tracker.**

> Explainer: The "issue tracker" is where issues live for this repo. Skills like `to-tickets`, `triage`, and `to-spec` read from and write to it. They need to know whether to call `gh issue create`, write a markdown file under `.scratch/`, or follow some other workflow you describe. Pick the place you actually track work for this repo.

Default posture: these skills were designed for GitHub. If a `git remote` points at GitHub, propose that. If a `git remote` points at GitLab (`gitlab.com` or a self-hosted host), propose GitLab. Otherwise (or if the user prefers), offer:

- **GitHub**: issues live in the repo's GitHub Issues (uses the `gh` CLI)
- **GitLab**: issues live in the repo's GitLab Issues (uses the [`glab`](https://gitlab.com/gitlab-org/cli) CLI)
- **Local markdown**: issues live as files under `.scratch/<feature>/` in this repo (good for solo projects or repos without a remote)
- **Other** (Jira, Linear, etc.): ask the user to describe the workflow in one paragraph; the skill will record it as freeform prose

Record the choice in `docs/agents/issue-tracker.md`. The GitHub and GitLab templates carry a "PRs as a request surface" flag, defaulted **off**. Leave it off and don't raise it: a user who wants external PRs in the triage queue can flip the flag in the file later.

**Section B: Triage label vocabulary.** Skip this section entirely if the `triage` skill isn't installed (exploration told you), since an uninstalled skill needs no labels.

If it is installed, ask exactly one question:

> Do you want to keep the default triage labels? (recommended: **yes**)

The defaults are the five canonical roles, each label string equal to its name: `needs-triage`, `needs-info`, `ready-for-agent`, `ready-for-human`, `wontfix`. On **yes**, write them as-is. Only if the user says no, usually because their tracker already uses other names (e.g. `bug:triage` for `needs-triage`), collect the overrides so `triage` applies existing labels instead of creating duplicates.

**Section C: Domain docs.** Default to **single-context** (one `CONTEXT.md` + `docs/adr/` at the repo root). This fits almost every repo; write it without asking.

Offer **multi-context** (a root `CONTEXT-MAP.md` pointing to per-context `CONTEXT.md` files) only when exploration found monorepo signals. Then confirm which layout they want.

### 3. Confirm and edit

Show the user a draft of:

- The `## Agent skills` block to add to whichever of `CLAUDE.md` / `AGENTS.md` is being edited (see step 4 for selection rules)
- The contents of `docs/agents/issue-tracker.md`, `docs/agents/domain.md`, and `docs/agents/triage-labels.md` (the last only when `triage` is installed)

Let them edit before writing.

### 4. Write

**Pick the file to edit:**

- If `CLAUDE.md` exists, edit it.
- Else if `AGENTS.md` exists, edit it.
- If neither exists, ask the user which one to create; don't pick for them.

Never create `AGENTS.md` when `CLAUDE.md` already exists (or vice versa); always edit the one that's already there.

If an `## Agent skills` block already exists in the chosen file, update its contents in-place rather than appending a duplicate. Don't overwrite user edits to the surrounding sections.

The block:

```markdown
## Agent skills

### Issue tracker

[one-line summary of where issues are tracked]. See `docs/agents/issue-tracker.md`.

### Triage labels

[one-line summary of the label vocabulary]. See `docs/agents/triage-labels.md`.

### Domain docs

[one-line summary of layout: "single-context" or "multi-context"]. See `docs/agents/domain.md`.
```

Include the `### Triage labels` sub-block, and write `docs/agents/triage-labels.md`, only when `triage` is installed and Section B ran. When it isn't, both are omitted.

Then write the docs files using the seed templates in this skill folder as a starting point:

- [issue-tracker-github.md](./issue-tracker-github.md): GitHub issue tracker
- [issue-tracker-gitlab.md](./issue-tracker-gitlab.md): GitLab issue tracker
- [issue-tracker-local.md](./issue-tracker-local.md): local-markdown issue tracker
- [triage-labels.md](./triage-labels.md): label mapping (only if `triage` is installed)
- [domain.md](./domain.md): domain doc consumer rules + layout

For "other" issue trackers, write `docs/agents/issue-tracker.md` from scratch using the user's description.

### 5. Done

Tell the user the setup is complete and which engineering skills will now read from these files. Mention they can edit `docs/agents/*.md` directly later; re-running this skill is only necessary if they want to switch issue trackers or restart from scratch.

Referenced files: 6

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---
name: to-tickets
description: Break a plan, spec, or the current conversation into a set of tracer-bullet tickets, each declaring its blocking edges, published to the configured tracker (edges as text in one file per ticket locally, or native blocking links on a real tracker).
disable-model-invocation: true
---

# To Tickets

Break a plan, spec, or conversation into a set of **tickets**: tracer-bullet vertical slices, each declaring the tickets that **block** it.

The issue tracker and triage label vocabulary should have been provided to you. If not, tell the user to run `/setup-matt-pocock-skills`.

## Process

### 1. Gather context

Work from whatever is already in the conversation context. If the user passes a reference (a spec path, an issue number or URL) as an argument, fetch it and read its full body and comments.

### 2. Explore the codebase (optional)

If you have not already explored the codebase, do so to understand the current state of the code. Ticket titles and descriptions should use the project's domain glossary vocabulary, and respect ADRs in the area you're touching.

Look for opportunities to prefactor the code to make the implementation easier. "Make the change easy, then make the easy change."

### 3. Draft vertical slices

Break the work into **tracer bullet** tickets.

<vertical-slice-rules>

- Each slice cuts a narrow but COMPLETE path through every layer (schema, API, UI, tests): vertical, NOT a horizontal slice of one layer
- A completed slice is demoable or verifiable on its own
- Each slice is sized to fit in a single fresh context window
- Any prefactoring should be done first

</vertical-slice-rules>

Give each ticket its **blocking edges**: the other tickets that must complete before it can start. A ticket with no blockers can start immediately.

**Wide refactors are the exception to vertical slicing.** A **wide refactor** is one mechanical change (rename a column, retype a shared symbol) whose **blast radius** fans across the whole codebase, so a single edit breaks thousands of call sites at once and no vertical slice can land green. Don't force it into a tracer bullet; sequence it as **expand–contract**. First expand: add the new form beside the old so nothing breaks. Then migrate the call sites over in batches sized by blast radius (per package, per directory), each batch its own ticket blocked by the expand, keeping CI green batch to batch because the old form still exists. Finally contract: delete the old form once no caller remains, in a ticket blocked by every migrate batch. When even the batches can't stay green alone, keep the sequence but let them share an integration branch that all block a final integrate-and-verify ticket; green is promised only there.

### 4. Quiz the user

Present the proposed breakdown as a numbered list. For each ticket, show:

- **Title**: short descriptive name
- **Blocked by**: which other tickets (if any) must complete first
- **What it delivers**: the end-to-end behaviour this ticket makes work

Ask the user:

- Does the granularity feel right? (too coarse / too fine)
- Are the blocking edges correct: does each ticket only depend on tickets that genuinely gate it?
- Should any tickets be merged or split further?

Iterate until the user approves the breakdown.

### 5. Publish the tickets to the configured tracker

Publish the approved tickets. **How** depends on the tracker `/setup-matt-pocock-skills` configured; the tickets are the same either way, only the shape of the blocking edges changes:

- **Local files** → write one file per ticket under `.scratch/<feature-slug>/issues/<NN>-<slug>.md`, numbered from `01` in dependency order (blockers first). Each file's "Blocked by" lists the numbers/titles it depends on. Use the per-ticket file template below: one ticket per file, never a single combined file.
- **A real issue tracker (GitHub, Linear, …)** → publish one issue per ticket in dependency order (blockers first) so each ticket's blocking edges can reference real identifiers. Use the platform's native blocking / sub-issue relationship where it has one; otherwise set each ticket's "Blocked by" to the blocking issues. Apply the `ready-for-agent` triage label unless instructed otherwise; the tickets are agent-grabbable by construction.

Work the **frontier**: any ticket whose blockers are all done. For a purely linear chain that means top to bottom.

Do NOT close or modify any parent issue.

<local-ticket-template>

# <NN>: <Ticket title>

**What to build:** the end-to-end behaviour this ticket makes work, from the user's perspective, not a layer-by-layer implementation list.

**Blocked by:** the numbers/titles of the tickets that gate this one, or "None (can start immediately)".

**Status:** ready-for-agent

- [ ] Acceptance criterion 1
- [ ] Acceptance criterion 2

</local-ticket-template>

<issue-template>

## Parent

A reference to the parent issue on the tracker (if the source was an existing issue, otherwise omit this section).

## What to build

The end-to-end behaviour this ticket makes work, from the user's perspective, not layer-by-layer implementation.

## Acceptance criteria

- [ ] Criterion 1
- [ ] Criterion 2

## Blocked by

- A reference to each blocking ticket, or "None (can start immediately)".

</issue-template>

In either form, avoid specific file paths or code snippets: they go stale fast. Exception: if a prototype produced a snippet that encodes a decision more precisely than prose can (state machine, reducer, schema, type shape), inline it and note briefly that it came from a prototype. Trim to the decision-rich parts, not a working demo, just the important bits.

Referenced files: 1