feat: Add new skills and templates for domain modeling, bug diagnosis, and architectural improvement

- Introduced a human-in-the-loop script for bug diagnosis to capture user feedback.
- Created ADR and CONTEXT formats to standardize architectural decision records and domain context documentation.
- Developed a domain modeling skill to refine terminology and maintain a shared language.
- Enhanced the improve-codebase-architecture skill to provide visual reports and deepening opportunities.
- Consolidated grilling and handoff skills for better user interaction and documentation.
- Updated existing skills to improve clarity and consistency in descriptions and functionality.

skills/engineering/improve-codebase-architecture/SKILL.md

@@ -1,38 +1,23 @@
 ---
 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.
+description: Scan a codebase for deepening opportunities, present them as a visual HTML report, then grill through whichever one you pick.
+disable-model-invocation: true
 ---
 
 # 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
+This command is _informed_ by the project's domain model and built on a shared design vocabulary:
 
-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. The domain language gives names to good seams; ADRs record decisions the skill should not re-litigate.
+- Run the `/codebase-design` skill for the architecture vocabulary (**module**, **interface**, **depth**, **seam**, **adapter**, **leverage**, **locality**) and its principles (the deletion test, "the interface is the test surface", "one adapter = hypothetical seam, two = real"). Use these terms exactly in every suggestion — don't drift into "component," "service," "API," or "boundary."
+- The domain language in `CONTEXT.md` gives names to good seams; ADRs in `docs/adr/` record decisions this command should not re-litigate.
 
 ## Process
 
 ### 1. Explore
 
-Read the project's domain glossary and any ADRs in the area you're touching first.
+Read the project's domain glossary (`CONTEXT.md`) and any ADRs in the area you're touching first.
 
 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:
 
@@ -50,7 +35,7 @@ Write a self-contained HTML file to the OS temp directory so nothing lands in th
 
 The report uses **Tailwind via CDN** for layout and styling, and **Mermaid via CDN** for diagrams where a graph/flow/sequence reliably communicates the structure. Mix Mermaid with hand-crafted CSS/SVG visuals — use Mermaid when relationships are graph-shaped (call graphs, dependencies, sequences), and hand-built divs/SVG when you want something more editorial (mass diagrams, cross-sections, collapse animations). Each candidate gets a **before/after visualisation**. Be visual.
 
-For each candidate, the same template as before, but rendered as a card:
+For each candidate, render a card with:
 
 - **Files** — which files/modules are involved
 - **Problem** — why the current architecture is causing friction
@@ -61,7 +46,7 @@ For each candidate, the same template as before, but rendered as a card:
 
 End the report with a **Top recommendation** section: which candidate you'd tackle first and why.
 
-**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."
+**Use CONTEXT.md vocabulary for the domain, and the `/codebase-design` 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 in the card (e.g. a warning callout: _"contradicts ADR-0007 — but worth reopening because…"_). Don't list every theoretical refactor an ADR forbids.
 
@@ -71,11 +56,11 @@ Do NOT propose interfaces yet. After the file is written, ask the user: "Which o
 
 ### 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.
+Once the user picks a candidate, run the `/grilling` skill to 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:
+Side effects happen inline as decisions crystallize — run the `/domain-modeling` skill to keep the domain model current as you go:
 
-- **Naming a deepened module after a concept not in `CONTEXT.md`?** Add the term to `CONTEXT.md` — same discipline as `/grill-with-docs` (see [CONTEXT-FORMAT.md](../grill-with-docs/CONTEXT-FORMAT.md)). Create the file lazily if it doesn't exist.
+- **Naming a deepened module after a concept not in `CONTEXT.md`?** Add the term to `CONTEXT.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](../grill-with-docs/ADR-FORMAT.md).
-- **Want to explore alternative interfaces for the deepened module?** See [INTERFACE-DESIGN.md](INTERFACE-DESIGN.md).
+- **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.
+- **Want to explore alternative interfaces for the deepened module?** Run the `/codebase-design` skill and use its design-it-twice parallel sub-agent pattern.