fix: correct stale claims in the router and the READMEs

Coherence pass over the rewritten docs set. The recurring defect was a
refactor whose removals landed and whose replacements did not.

- tdd: restore the pointer to /codebase-design that the v1.0 changelog
  and ask-matt both claim exists. The inline deep-module notes were
  deleted then; nothing replaced them.
- ask-matt: /grilling and /resolving-merge-conflicts were missing from
  the router entirely. Split grill-me from grill-with-docs on the
  working directory rather than on whether the subject is code.
- READMEs: wayfinder maps decision tickets, not investigation tickets;
  the diagnosing-bugs loop starts by building a loop that goes red;
  improve-codebase-architecture is a survey, not a rescue; grilling
  resolves a design tree and is the primitive behind five skills.
- Drop the /implement reliability claim from the implement and tdd
  pages.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

skills/engineering/README.md

@@ -23,7 +23,7 @@ Model- or user-reachable (rich trigger phrasing so the model can reach for them)
 
 - **[prototype](./prototype/SKILL.md)** — Build a throwaway prototype to answer a design question: a single shareable HTML file for state/logic, or several toggleable UI variations.
 
-- **[diagnosing-bugs](./diagnosing-bugs/SKILL.md)** — Disciplined diagnosis loop for hard bugs and performance regressions: reproduce → minimise → hypothesise → instrument → fix → regression-test.
+- **[diagnosing-bugs](./diagnosing-bugs/SKILL.md)** — Disciplined diagnosis loop for hard bugs and performance regressions: build a feedback loop that goes red on this bug → minimise → hypothesise → instrument → fix → regression-test.
 - **[research](./research/SKILL.md)** — Investigate a question against high-trust primary sources and capture the findings as a cited Markdown file in the repo, run as a background agent.
 - **[tdd](./tdd/SKILL.md)** — Test-driven development with a red-green-refactor loop. Builds features or fixes bugs one vertical slice at a time.
 - **[domain-modeling](./domain-modeling/SKILL.md)** — Actively build and sharpen a project's domain model — challenge terms, stress-test with scenarios, update `CONTEXT.md` and ADRs inline.

skills/engineering/ask-matt/SKILL.md

@@ -14,7 +14,7 @@ A **flow** is a path through the skills. Most paths run along one **main flow**,
 
 The route most work travels. You have an idea and want it built.
 
-1. **`/grill-with-docs`** — sharpen the idea by interview. Start here when you **have a codebase**: it's stateful, retaining what it learns in `CONTEXT.md` and ADRs. (No codebase? Use `/grill-me` — see Standalone. Both run the same `/grilling` primitive; `grill-with-docs` is the one that leaves a paper trail.)
+1. **`/grill-with-docs`** — sharpen the idea by interview. Start here whenever you are **working in a working directory**: it's stateful, retaining what it learns in `CONTEXT.md` and ADRs. (No working directory? Use `/grill-me` — see Standalone. Both run the same `/grilling` primitive; `grill-with-docs` is the one that leaves a paper trail, which makes it the better of the two whenever a repo is there to leave it in.)
 2. **Branch — can you settle every question in conversation?** If a question needs a runnable answer (state, business logic, a UI you have to see), detour through a prototype, bridged by **`/handoff`** in both directions (a prototype lives in its own directory, which is exactly what `/handoff` is for — see Phase boundaries):
    - **`/handoff`** out, then open a fresh session against that file,
    - **`/prototype`** to answer the question with throwaway code,
@@ -74,7 +74,9 @@ Read [PHASE-BOUNDARIES.md](PHASE-BOUNDARIES.md) for the ordered tree — the fiv
 
 Off the main flow entirely.
 
-- **`/grill-me`** — the same relentless interview as `/grill-with-docs`, but for when you have **no codebase**. Stateless: it saves nothing locally, builds no `CONTEXT.md`. Reach for it to sharpen any plan or design that doesn't live in a repo.
+- **`/grill-me`** — the same relentless interview as `/grill-with-docs`, but **stateless**: it saves nothing locally and builds no `CONTEXT.md`. Reach for it when you are **not working in a working directory** — sharpening a plan, a design, a piece of writing, anything with no repo under it. If you are in a working directory, use `/grill-with-docs` instead: it runs the same interview and leaves a paper trail, so it is strictly the better one.
+- **`/grilling`** — the interview primitive itself: rounds, the frontier, facts are the agent's job and decisions are yours. `/grill-me` and `/grill-with-docs` are the two named ways in, and `/triage`, `/wayfinder` and `/improve-codebase-architecture` all run it internally. Reach for it directly only when you want the interview with no wrapper around it.
+- **`/resolving-merge-conflicts`** — work an in-progress merge or rebase conflict hunk by hunk, resolving by **intent** traced to each side's primary source rather than by picking lines, then finish the operation. It never runs `--abort`. Standalone and off every flow: reach for it when you are already mid-conflict.
 - **`/prototype`** — a small, throwaway program that answers one design question: does this state model feel right, or what should this UI look like. Throwaway is a constraint on how the code is written, not a promise to destroy it: the answer folds into the real code, and the prototype itself is kept as a **primary source** on a `prototype/<name>` branch out of main, pointed at from the implementation issue. It's the detour in step 2 of the main flow, but reach for it any time a design question is hard to settle on paper.
 - **`/research`** — delegate reading legwork to a **background agent**: it investigates a question against **primary sources**, then leaves a cited Markdown file in the repo. Keep working while it reads. The file it produces is something to take *into* the main flow at `/grill-with-docs` — research feeds the thinking, it doesn't replace it.
 - **`/to-questionnaire`** — when the thing blocking you isn't in your head or the codebase but in **someone else's**, this writes them a questionnaire to fill in. It's the inverse of `/grill-me`: instead of interviewing you about the subject, it interviews you about the **send** — who it's going to, what you need back — and aims the questions at the gap. What comes back is material for `/grill-with-docs` or `/to-spec`.

skills/engineering/tdd/SKILL.md

@@ -23,6 +23,8 @@ A **seam** is the public boundary you test at: the interface where you observe b
 
 Ask: "What's the public interface, and which seams should we test?"
 
+When the shape of that interface is itself in question — how deep the module is, where the seam belongs, what the interface should expose — use the `/codebase-design` skill for the vocabulary. It is the shared source of the module, interface, depth, seam, adapter, leverage and locality terms, and it is a reference to consult, not a session to run.
+
 ## Anti-patterns
 
 - **Implementation-coupled** — mocks internal collaborators, tests private methods, or verifies through a side channel (querying the database instead of using the interface). The tell: the test breaks when you refactor but behavior hasn't changed.