Merge pull request #403 from mattpocock/docs/skill-pages-remaining

docs: pages for the remaining 22 promoted skills

Author: mattpocock

.agents/writing-docs.md

@@ -1,10 +1,10 @@
 # Writing docs pages
 
-Every promoted skill (`engineering/`, `productivity/`, `misc/`) has a human-facing **docs page** at `docs/<bucket>/<skill-name>.md` — the docs tree mirrors the bucket folders under `skills/`. It is published at `https://aihero.dev/skills-<skill-name>`; the URL is always `skills-<skill-name>` regardless of bucket, so the docs path is repo organisation only. The page is not the skill and not a copy of `SKILL.md`.
+Every skill in `engineering/` and `productivity/` has a human-facing **docs page** at `docs/<bucket>/<skill-name>.md` — the docs tree mirrors those two bucket folders under `skills/`. It is published at `https://aihero.dev/skills-<skill-name>`; the URL is always `skills-<skill-name>` regardless of bucket, so the docs path is repo organisation only. The page is not the skill and not a copy of `SKILL.md`. Only these two buckets are promoted; the rest (`misc/`, `personal/`, `in-progress/`, `deprecated/`) ship no docs page.
 
 Most of these skills are **user-invoked**: the agent will never fire them for you, so *you* are the index that has to remember they exist and when to reach for them. That memory is **cognitive load**. The job of a docs page is to relieve it — to orient one reader around one skill so they can hold it in their head, know when to reach for it, and see where it sits in the system. The pages are collectively a distributed router; each is a node.
 
-Act whenever a promoted skill is added, renamed, or has its behaviour changed: create or re-sync its docs page. A rename moves the file too (`docs/<bucket>/<old>.md` → `docs/<bucket>/<new>.md`), because the published URL tracks the name; a skill that moves buckets moves its docs file to the matching folder. Skills in `personal/`, `in-progress/`, and `deprecated/` get no page, mirroring the README rule.
+Act whenever a promoted skill is added, renamed, or has its behaviour changed: create or re-sync its docs page. A rename moves the file too (`docs/<bucket>/<old>.md` → `docs/<bucket>/<new>.md`), because the published URL tracks the name; a skill that moves between `engineering/` and `productivity/` moves its docs file to the matching folder. Skills in `misc/`, `personal/`, `in-progress/`, and `deprecated/` get no page — none of those buckets is promoted. A skill moving *out* of one of them into `engineering/` or `productivity/` gains a page; one moving the other way loses it.
 
 Because these pages are published on `aihero.dev`, **every link is absolute** — never a repo-relative path. A link to another skill points at `https://aihero.dev/skills-<name>`; a link into the repo points at its full `https://github.com/mattpocock/skills/...` URL. A relative link that works in the repo breaks once published.
 
@@ -30,7 +30,7 @@ npx skills update <name>
 
 ## What it does
 
-One or two plain-language paragraphs. Lead with the skill's one-sentence job, then state the **load-bearing constraint** — the single fact that makes this skill behave differently from the obvious default (for `to-prd`: it does not interview the user again, it synthesises what is already known). This line is the most valuable on the page; never omit it.
+One or two plain-language paragraphs. Lead with the skill's one-sentence job, then state the **defining constraint** — the single fact that makes this skill behave differently from the obvious default (for `to-prd`: it does not interview the user again, it synthesises what is already known). Write it as a plain declarative sentence — never a labelled aside like "The defining constraint:" or "The key thing:"; the formula reads as filler. This line is the most valuable on the page; never omit it.
 
 ## When to reach for it
 
@@ -47,7 +47,7 @@ Optional — include only when the skill needs something in place to be function
 
 One to three short sections, in the skill's *own vocabulary*, that make it click — choose whatever headings fit the skill: the loop it runs, the artifact it produces, the fork it makes, the one anti-pattern it kills. There is no prescribed heading; the skills are too heterogeneous for one.
 
-The single non-negotiable: **surface the skill's leading word / load-bearing idea** — `tight` feedback loop, `deep module`, throwaway-code-answers-a-question, red-green. It pays off twice: the reader learns what the skill *is*, and learns the word they'll later think with to *reach for* it.
+The single non-negotiable: **surface the skill's leading word / defining idea** — `tight` feedback loop, `deep module`, throwaway-code-answers-a-question, red-green. It pays off twice: the reader learns what the skill *is*, and learns the word they'll later think with to *reach for* it.
 
 ## It's working if
 
@@ -73,7 +73,7 @@ Always present. Situate the skill in the system in a sentence or two:
 
 - The page exists at `docs/<bucket>/<name>.md`, and no stale page survives a rename or bucket move.
 - The Quickstart block and source link name the correct bucket and skill; the update line names the skill.
-- `## What it does` states the load-bearing constraint.
+- `## What it does` states the defining constraint, as plain prose rather than a labelled aside.
 - `## When to reach for it` states invocation mode and the trigger boundary.
 - `## Where it fits` names the role and links to `ask-matt`.
 - A prerequisite (workspace, prior setup, tooling) is stated where one exists, and the section is absent where none does.

CLAUDE.md

@@ -2,18 +2,18 @@ Skills are organized into bucket folders under `skills/`:
 
 - `engineering/` — daily code work
 - `productivity/` — daily non-code workflow tools
-- `misc/` — kept around but rarely used
+- `misc/` — kept around but rarely used, not promoted
 - `personal/` — tied to my own setup, not promoted
 - `in-progress/` — drafts not yet ready to ship
 - `deprecated/` — no longer used
 
-Every skill in `engineering/`, `productivity/`, or `misc/` must have a reference in the top-level `README.md` and an entry in `.claude-plugin/plugin.json`. Skills in `personal/`, `in-progress/`, and `deprecated/` must not appear in either.
+Every skill in `engineering/` or `productivity/` (the **promoted** buckets) must have a reference in the top-level `README.md` and an entry in `.claude-plugin/plugin.json`. Skills in `misc/`, `personal/`, `in-progress/`, and `deprecated/` must not appear in either.
 
 Each skill entry in the top-level `README.md` must link the skill name to its `SKILL.md`.
 
-Each bucket folder has a `README.md` that lists every skill in the bucket with a one-line description, with the skill name linked to its `SKILL.md`. Bucket `README.md`s and the top-level `README.md` group entries into **User-invoked** and **Model-invoked**.
+Each bucket folder has a `README.md` that lists every skill in the bucket with a one-line description, with the skill name linked to its `SKILL.md`. The promoted buckets' `README.md`s and the top-level `README.md` group entries into **User-invoked** and **Model-invoked**; non-promoted bucket `README.md`s (`misc/`, `personal/`) use a flat list.
 
-Every promoted skill also has a human-facing docs page at `docs/<bucket>/<skill-name>.md` (the docs tree mirrors the bucket folders under `skills/`). The published URL is `https://aihero.dev/skills-<skill-name>` regardless of bucket — the docs path is repo organisation only. When you add, rename, or change the behaviour of a skill in `engineering/`, `productivity/`, or `misc/`, create or re-sync its docs page following [.agents/writing-docs.md](./.agents/writing-docs.md).
+Skills in `engineering/` and `productivity/` also have a human-facing docs page at `docs/<bucket>/<skill-name>.md` (the docs tree mirrors those two bucket folders under `skills/`). The published URL is `https://aihero.dev/skills-<skill-name>` regardless of bucket — the docs path is repo organisation only. When you add, rename, or change the behaviour of a skill in `engineering/` or `productivity/`, create or re-sync its docs page following [.agents/writing-docs.md](./.agents/writing-docs.md). Skills in the non-promoted buckets (`misc/`, `personal/`, `in-progress/`, `deprecated/`) get **no** docs page.
 
 Every `SKILL.md` is either user-invoked (`disable-model-invocation: true`, reachable only by the human) or model-invoked (model- or user-reachable). See [.agents/invocation.md](./.agents/invocation.md).
 

README.md

@@ -179,12 +179,3 @@ General workflow tools, not code-specific.
 **Model-invoked**
 
 - **[grilling](./skills/productivity/grilling/SKILL.md)** — Interview the user relentlessly about a plan or design until every branch of the decision tree is resolved. The reusable loop behind `grill-me` and `grill-with-docs`.
-
-### Misc
-
-Tools I keep around but rarely use.
-
-- **[git-guardrails-claude-code](./skills/misc/git-guardrails-claude-code/SKILL.md)** — Set up Claude Code hooks to block dangerous git commands (push, reset --hard, clean, etc.) before they execute.
-- **[migrate-to-shoehorn](./skills/misc/migrate-to-shoehorn/SKILL.md)** — Migrate test files from `as` type assertions to @total-typescript/shoehorn.
-- **[scaffold-exercises](./skills/misc/scaffold-exercises/SKILL.md)** — Create exercise directory structures with sections, problems, solutions, and explainers.
-- **[setup-pre-commit](./skills/misc/setup-pre-commit/SKILL.md)** — Set up Husky pre-commit hooks with lint-staged, Prettier, type checking, and tests.

docs/engineering/ask-matt.md

@@ -0,0 +1,31 @@
+Quickstart:
+
+```bash
+npx skills add mattpocock/skills --skill=ask-matt
+```
+
+```bash
+npx skills update ask-matt
+```
+
+[Source](https://github.com/mattpocock/skills/tree/main/skills/engineering/ask-matt)
+
+## What it does
+
+`ask-matt` is the router over every user-invoked skill in this repo. You describe the situation you're in; it tells you which skill or flow fits and in what order to run them.
+
+It **does no work itself**. It doesn't grill, write a PRD, or fix anything — it only orients. Because these skills are user-invoked, nothing fires them for you, so *you* have to remember they exist; `ask-matt` is the memory you offload that to. It answers "which one, and when", then hands you off to the skill that actually does the job.
+
+## When to reach for it
+
+You invoke this by typing `/ask-matt` — the agent won't reach for it on its own.
+
+Reach for it whenever you're unsure which skill or flow a situation calls for: you have an idea and don't know where to start, a pile of bug reports and don't know if they're for `/triage`, or two skills that look interchangeable and you can't tell them apart. If you already know the skill you want, skip the router and invoke it directly.
+
+## Flows, not just skills
+
+The idea `ask-matt` gives you to think with is the **flow** — a path *through* the skills rather than a single one. Most work runs along one **main flow** (idea → ship: grill → PRD → issues → implement), two **on-ramps** merge onto it (a triage lane for incoming bugs and requests; a codebase-health lane that generates ideas), and everything else is a **standalone** you reach for on its own. Ask a question and you get placed on the right flow, at the right step — not just handed a tool.
+
+## Where it fits
+
+`ask-matt` is the **router** — the standalone map that sits over the whole set. It is the node every other docs page links back to as [ask-matt](https://aihero.dev/skills-ask-matt), so it never sits *in* a chain; it points *into* every chain. From here you'll most often land on [grill-with-docs](https://aihero.dev/skills-grill-with-docs), the head of the main flow, or [triage](https://aihero.dev/skills-triage), the on-ramp for work you didn't create. When even the router's own picture is stale, its [Source](https://github.com/mattpocock/skills/tree/main/skills/engineering/ask-matt) is the map of record.

docs/engineering/codebase-design.md

@@ -0,0 +1,43 @@
+Quickstart:
+
+```bash
+npx skills add mattpocock/skills --skill=codebase-design
+```
+
+```bash
+npx skills update codebase-design
+```
+
+[Source](https://github.com/mattpocock/skills/tree/main/skills/engineering/codebase-design)
+
+## What it does
+
+`codebase-design` gives you a shared, precise vocabulary for designing **deep modules** — a lot of behaviour hidden behind a small interface, placed at a clean seam, testable through that interface.
+
+It is a **language, not a procedure**. It doesn't restructure your code or hand you a refactor plan — it fixes the words (module, interface, depth, seam, adapter, leverage, locality) so that every design conversation and every other skill that touches design speaks the same way. Consistent language is the whole point; "component," "service," "API," and "boundary" are deliberately banned because they blur the distinctions that matter.
+
+## When to reach for it
+
+Type `/codebase-design`, or the agent reaches for it automatically when a task fits.
+
+Reach for it when you're designing or improving a module's interface, hunting for deepening opportunities, deciding where a seam goes, or making code more testable and AI-navigable. Other skills pull it in whenever they need the deep-module vocabulary. If you want to sharpen the project's *domain* terms rather than its module design, use [domain-modeling](https://aihero.dev/skills-domain-modeling) instead; to run a whole architecture pass over an existing codebase, use [improve-codebase-architecture](https://aihero.dev/skills-improve-codebase-architecture).
+
+## Deep, not shallow
+
+A module is **deep** when a large amount of behaviour sits behind a small interface, and **shallow** when the interface is nearly as complex as the implementation. Depth is measured as **leverage** — how much a caller (or a test) can exercise per unit of interface they have to learn. Crucially, depth is a property of the *interface*, not the implementation: a deep module can be internally composed of small, swappable parts that just never surface to callers.
+
+Two checks do most of the work. The **deletion test**: imagine deleting the module — if complexity vanishes, it was a pass-through; if it reappears across N callers, it was earning its keep. And **one adapter means a hypothetical seam; two adapters means a real one** — don't cut a seam until something actually varies across it.
+
+## The interface is the test surface
+
+Callers and tests cross the same seam, so a well-placed interface gives tests something durable to aim at while the code underneath moves freely. That's why the vocabulary insists on **seam** (Feathers' term — a place you can change behaviour without editing there) over the overloaded "boundary," and why "interface" here means *every fact a caller must know*: signatures, yes, but also invariants, ordering, error modes, and performance — not just the type-level surface.
+
+## Pulled out on purpose
+
+`codebase-design` is the **single source of truth** for the deep-module vocabulary, split out as its own model-invoked skill so anything can reach it. Other skills point at it rather than restating the words: [tdd](https://aihero.dev/skills-tdd) borrows it to place a seam before writing the test, [improve-codebase-architecture](https://aihero.dev/skills-improve-codebase-architecture) leans on it while restructuring existing code, and [to-prd](https://aihero.dev/skills-to-prd) speaks it when it sketches seams and deepening opportunities before writing a spec.
+
+The point of keeping it standalone is that you can also reach for it on its own — as a **reference** for how to think about module design — without triggering the larger process any of those skills mandate. Fix the words once, in one place, and every design conversation inherits them.
+
+## Where it fits
+
+`codebase-design` is a **reach-for-it-anytime standalone** — the shared vocabulary layer under the engineering skills. Its closest neighbour is [domain-modeling](https://aihero.dev/skills-domain-modeling), the parallel vocabulary skill for the problem domain rather than the module structure. When you're unsure which skill or flow fits, [ask-matt](https://aihero.dev/skills-ask-matt) routes you.

docs/engineering/diagnosing-bugs.md

@@ -0,0 +1,40 @@
+Quickstart:
+
+```bash
+npx skills add mattpocock/skills --skill=diagnosing-bugs
+```
+
+```bash
+npx skills update diagnosing-bugs
+```
+
+[Source](https://github.com/mattpocock/skills/tree/main/skills/engineering/diagnosing-bugs)
+
+## What it does
+
+`diagnosing-bugs` runs a disciplined diagnosis loop for hard bugs and performance regressions — building a repro, minimising it, ranking hypotheses, instrumenting, then fixing with a regression test.
+
+It refuses to hypothesise before you have a **tight feedback loop** — one runnable command that already goes red on *this* bug. Reading code to build a theory before that command exists is the exact failure this skill prevents. No red-capable loop, no diagnosis.
+
+## When to reach for it
+
+Type `/diagnosing-bugs`, or the agent reaches for it automatically when a task fits — it fires on "diagnose" / "debug this", or when you report something broken, throwing, failing, or slow.
+
+Reach for it on the hard ones: the bug that resists a first glance, the intermittent flake, the regression that crept in between two known-good states. For a quick throwaway to sanity-check a design question rather than chase a defect, use [prototype](https://aihero.dev/skills-prototype) instead.
+
+## The tight loop is the skill
+
+Everything else — bisection, hypothesis-testing, instrumentation — is mechanical once you have the signal. So the skill spends disproportionate effort on Phase 1: constructing a pass/fail command that drives the actual bug code path and asserts the user's exact symptom, then **tightening** it until it is fast, deterministic, and agent-runnable. A 30-second flaky loop is barely better than none; a 2-second deterministic one is a debugging superpower.
+
+It gives you a ladder of ways to build that loop — failing test, curl script, CLI diff, headless browser, replayed trace, throwaway harness, fuzz loop, `git bisect run`, differential run — and, only as a last resort, a human-in-the-loop bash script. For non-deterministic bugs the goal isn't a clean repro but a **higher reproduction rate**: loop the trigger, parallelise, add stress until the flake is debuggable.
+
+## It's working if
+
+- It builds and runs a repro command *before* theorising — and pastes the invocation and its red output.
+- The loop asserts the symptom you actually reported, not a nearby failure.
+- Hypotheses arrive as a ranked, falsifiable list shown to you before any are tested.
+- Debug instrumentation is tagged (`[DEBUG-...]`) and grepped away before it declares done.
+
+## Where it fits
+
+`diagnosing-bugs` is a reach-for-it-anytime standalone — you drop into it the moment something is broken, and drop out once the fix and its regression test are in. Its post-mortem hands off to [improve-codebase-architecture](https://aihero.dev/skills-improve-codebase-architecture) when the real finding is that there's no good seam to lock the bug down — the code, not the bug, is the problem. When you're unsure which skill fits, [ask-matt](https://aihero.dev/skills-ask-matt) routes you.