Merges domain vocabulary from CONTEXT.md into CLAUDE.md

CONTEXT.md was always-read only if explicitly fetched; CLAUDE.md is
automatically loaded into every agent context, so the vocabulary is
more reliably available there.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: nicklemmon

.agents/skills/codebase-design/DEEPENING.md

@@ -1,37 +1,53 @@
 # Deepening
 
-How to deepen a cluster of shallow modules safely, given its dependencies. Assumes the vocabulary in [SKILL.md](SKILL.md) — **module**, **interface**, **seam**, **adapter**.
+How to deepen a cluster of shallow modules safely, given its dependencies. Assumes the vocabulary in
+[SKILL.md](SKILL.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.
+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.
+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.
+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.
+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."*
+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.
+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.
+- **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.
+- 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.
+- 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.

.agents/skills/codebase-design/DESIGN-IT-TWICE.md

@@ -1,33 +1,46 @@
 # Design It Twice
 
-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.
+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 [SKILL.md](SKILL.md) — **module**, **interface**, **seam**, **adapter**, **leverage**.
+Uses the vocabulary in [SKILL.md](SKILL.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:
+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
+- 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.
+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.
+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:
+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 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 [SKILL.md](SKILL.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.
+Include both [SKILL.md](SKILL.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:
 
@@ -39,6 +52,10 @@ Each sub-agent outputs:
 
 ### 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**.
+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.
+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.

.agents/skills/codebase-design/SKILL.md

@@ -1,31 +1,52 @@
 ---
 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.
+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.
 ---
 
 # 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.
+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.
+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.
+**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).
+**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.
+**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.
+**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).
+**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).
+**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.
+**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.
+**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
 
@@ -59,10 +80,16 @@ When designing an interface, ask:
 
 ## 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.
+- **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
 
@@ -76,7 +103,7 @@ Good interfaces make testing natural:
 
    // Hard to test
    function processOrder(order) {
-     const gateway = new StripeGateway();
+     const gateway = new StripeGateway()
    }
    ```
 
@@ -88,7 +115,7 @@ Good interfaces make testing natural:
 
    // Hard to test
    function applyDiscount(cart): void {
-     cart.total -= discount;
+     cart.total -= discount
    }
    ```
 
@@ -104,11 +131,16 @@ Good interfaces make testing natural:
 
 ## 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.
+- **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.
+- **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.