docs: add human-facing pages for the remaining 22 promoted skills

Adds a docs page for every promoted skill that lacked one, following
.agents/writing-docs.md and using docs/engineering/to-prd.md as the
worked exemplar. Covers all of engineering/ (bar to-prd, already done),
productivity/, and misc/.

Each page states its load-bearing constraint, its invocation mode and
trigger boundary, surfaces the skill's leading word, and routes back to
ask-matt so the set forms a connected router with no dead ends.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/productivity/grill-me.md

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+Quickstart:
+
+```bash
+npx skills add mattpocock/skills --skill=grill-me
+```
+
+```bash
+npx skills update grill-me
+```
+
+[Source](https://github.com/mattpocock/skills/tree/main/skills/productivity/grill-me)
+
+## What it does
+
+`grill-me` runs a relentless interview about a plan or design, walking every branch of the decision tree until you and the agent reach a **shared understanding**.
+
+The load-bearing constraint: it asks **one question at a time** and waits. It never dumps a batch of questions at you — that is bewildering — and where a question can be answered by reading the codebase, it goes and reads rather than asking. Each question comes with the agent's own recommended answer, so you are reacting to a proposal, not staring at a blank prompt.
+
+## When to reach for it
+
+You invoke this by typing `/grill-me` — the agent won't reach for it on its own.
+
+Reach for it before you build, when a plan feels roughly right but you can sense unresolved decisions hiding in it — the moment you want the soft spots found and forced into the open. If you want that same interrogation to also leave a paper trail of ADRs and a glossary behind, use [grill-with-docs](https://aihero.dev/skills-grill-with-docs) instead.
+
+## The design tree
+
+The session walks the plan as a tree of decisions, resolving dependencies between them one by one — a parent decision settled before the choices that hang off it. The point is not to reach agreement quickly; it is to make every implicit call explicit, so nothing load-bearing is left assumed. You come out the other side with a plan whose branches have all been visited.
+
+`grill-me` is **stateless**: it writes nothing and leaves no workspace behind. It runs anywhere, and the only artifact is the sharpened understanding in the conversation itself. That is the deliberate contrast with [grill-with-docs](https://aihero.dev/skills-grill-with-docs), which captures the same interview as durable ADRs and a glossary.
+
+## Where it fits
+
+`grill-me` is a reach-for-it-anytime standalone — the pre-build stress test you run whenever a plan needs hardening. It is the stateless, user-invoked front door to the [grilling](https://aihero.dev/skills-grilling) primitive; its closest neighbour is [grill-with-docs](https://aihero.dev/skills-grill-with-docs), the stateful sibling that runs the same interview but additionally records the decisions as ADRs and a glossary. If the outcome is a spec you want written down, hand off to [to-prd](https://aihero.dev/skills-to-prd), which synthesises the settled understanding into a PRD without re-interviewing you. When you're unsure which flow fits, [ask-matt](https://aihero.dev/skills-ask-matt) routes you.

docs/productivity/grilling.md

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+Quickstart:
+
+```bash
+npx skills add mattpocock/skills --skill=grilling
+```
+
+```bash
+npx skills update grilling
+```
+
+[Source](https://github.com/mattpocock/skills/tree/main/skills/productivity/grilling)
+
+## What it does
+
+`grilling` is the relentless interview that stress-tests a plan or design before you build it. It walks down the design tree branch by branch, resolving the dependencies between decisions one at a time until you and the agent share the same understanding.
+
+The load-bearing constraint: it asks **one question at a time** and waits for your answer before the next — never a bulk list, which is bewildering. Each question comes with the agent's own recommended answer, and any question the codebase can settle it explores instead of asking you.
+
+## When to reach for it
+
+Type `/grilling`, or the agent reaches for it automatically when a task fits — this is the underlying primitive, not a user-only entry point.
+
+Reach for it when a plan or design still has soft spots and you want them surfaced before code is written. In practice you usually invoke it through one of its two wrappers rather than by name: for a plain grilling session use [grill-me](https://aihero.dev/skills-grill-me); to have the session also write ADRs and a glossary as it goes, use [grill-with-docs](https://aihero.dev/skills-grill-with-docs).
+
+## The design tree
+
+The mental model is a **design tree**: every plan branches into decisions, and decisions depend on each other. `grilling` descends that tree one node at a time, so an early answer can reshape which questions come next. That is why the questions arrive singly and in dependency order — a firehose of parallel questions loses the structure that makes the interview converge on a shared understanding.
+
+## Where it fits
+
+`grilling` is a **primitive** — the interview engine that [grill-me](https://aihero.dev/skills-grill-me) and [grill-with-docs](https://aihero.dev/skills-grill-with-docs) both run. Those two are the user-invoked front doors; `grilling` is the shared technique underneath, and it also opens the main build chain, sharpening context before [to-prd](https://aihero.dev/skills-to-prd) writes the spec. When you're unsure which entry point fits, [ask-matt](https://aihero.dev/skills-ask-matt) routes you.

docs/productivity/handoff.md

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+Quickstart:
+
+```bash
+npx skills add mattpocock/skills --skill=handoff
+```
+
+```bash
+npx skills update handoff
+```
+
+[Source](https://github.com/mattpocock/skills/tree/main/skills/productivity/handoff)
+
+## What it does
+
+`handoff` compacts the current conversation into a **handoff document** — a single write-up a fresh agent can read to pick up the work where you left off.
+
+The load-bearing constraint: it does **not** re-state what already lives elsewhere. Anything captured in a PRD, plan, ADR, issue, commit, or diff is referenced by path or URL, never copied. The document carries only the live thread — what you were doing, why, and what's next — and it's saved to your OS's temporary directory, not into the workspace, so it never becomes another artifact to maintain.
+
+## When to reach for it
+
+You invoke this by typing `/handoff` — the agent won't reach for it on its own. Pass a note about what the next session is for and the document is tailored to it.
+
+Reach for this when a conversation has gone long enough that its context is at risk — you're near a context limit, wrapping for the day, or deliberately handing the work to another agent — and you want the thread preserved without dragging the whole transcript along.
+
+## What the document carries
+
+- **The live thread** — what's in flight and why, in the conversation's own terms, minus anything already written down elsewhere.
+- **Suggested skills** — a pointer to the skills the next agent should reach for to continue.
+- **References, not copies** — links and paths to the PRDs, plans, ADRs, issues, and diffs that hold the settled detail.
+- **Redacted secrets** — API keys, passwords, and PII stripped before the document is written.
+
+The idea to hold onto is **compaction**: a handoff is the conversation squeezed down to just its resumable core, so a fresh agent inherits the momentum, not the noise.
+
+## Where it fits
+
+`handoff` is a reach-for-it-anytime standalone — it sits at the seam between two sessions rather than inside a build chain. It pairs naturally with the artifact-producing skills whose output it points at: [to-prd](https://aihero.dev/skills-to-prd), because a finished PRD is exactly the kind of settled detail a handoff references instead of repeating. When you're unsure which skill fits the moment, [ask-matt](https://aihero.dev/skills-ask-matt) routes you.

docs/productivity/teach.md

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+Quickstart:
+
+```bash
+npx skills add mattpocock/skills --skill=teach
+```
+
+```bash
+npx skills update teach
+```
+
+[Source](https://github.com/mattpocock/skills/tree/main/skills/productivity/teach)
+
+## What it does
+
+`teach` turns the current directory into a standing teaching workspace and teaches you one topic across many sessions — devising short, beautiful, interactive lessons tied to *why* you want to learn.
+
+The load-bearing constraint: it does **not** teach from the model's own memory. Parametric knowledge is treated as untrusted; before it can teach, it gathers high-trust resources and grounds every claim in a citation. And it is stateful — the workspace remembers what you've learned, so each session picks up where the last left off rather than starting from scratch.
+
+## When to reach for it
+
+You invoke this by typing `/teach` — the agent won't reach for it on its own.
+
+Reach for it when you want to *learn* a topic over time — a language, a framework, yoga, theoretical physics — and want the sessions to accumulate rather than evaporate. It is not for a one-off explanation; if you just need something clarified in the moment, ask directly. Reach for `teach` when the learning is a project.
+
+## Prerequisites
+
+`teach` builds a whole directory in place, so run it somewhere you're happy to keep as a dedicated workspace. Over time it writes:
+
+- `MISSION.md` — the reason you're learning this, which grounds everything else. If it's empty, `teach`'s first job is to question you until it isn't.
+- `RESOURCES.md` — the vetted, high-trust sources it teaches from.
+- `./lessons/*.html` — the numbered, self-contained lessons (the primary unit of teaching).
+- `./reference/*.html` — compressed cheat-sheets, algorithms, glossaries you'll return to.
+- `./learning-records/*.md` — what you've learned, ADR-style, used to judge what to teach next.
+- `./assets/*` — reusable components (a shared stylesheet first) so the lessons look like one course.
+- `NOTES.md` — your teaching preferences.
+
+## Mission, and the zone of proximal development
+
+Every lesson hangs off the **mission**. Without it, knowledge has nothing to attach to and lessons feel abstract — so the mission is the first thing `teach` pins down and keeps updating as you grow. From the mission and your learning records it computes your **zone of proximal development**: the next lesson should challenge you *just enough*, no more.
+
+## Storage strength, not fluency
+
+The word to think with is **storage strength** — long-term retention — as opposed to **fluency**, the in-the-moment recall that feels like mastery but isn't. `teach` deliberately builds the former through desirable difficulty: retrieval practice, spacing, and interleaving. Knowledge is taught first (where difficulty is the enemy), then skills are drilled through a tight feedback loop (where difficulty is the tool).
+
+## Where it fits
+
+`teach` is a reach-for-it-anytime standalone — a long-running learning project you drive session by session, not a step in a build chain. It shares no workflow with the other productivity skills; it simply owns its workspace directory and lives there. When you're unsure which skill or flow fits, [ask-matt](https://aihero.dev/skills-ask-matt) routes you.

docs/productivity/writing-great-skills.md

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+Quickstart:
+
+```bash
+npx skills add mattpocock/skills --skill=writing-great-skills
+```
+
+```bash
+npx skills update writing-great-skills
+```
+
+[Source](https://github.com/mattpocock/skills/tree/main/skills/productivity/writing-great-skills)
+
+## What it does
+
+`writing-great-skills` is the reference you write and edit skills against — the shared vocabulary and principles that make a skill predictable.
+
+The load-bearing constraint: a skill's job is to wrangle determinism out of a stochastic system, so the goal is not the same *output* every run but the same *process*. **Predictability** is the root virtue, and every design choice is judged against it — not against how clever, complete, or exhaustive the skill reads.
+
+## When to reach for it
+
+You invoke this by typing `/writing-great-skills` — the agent won't reach for it on its own.
+
+Reach for it whenever you're authoring a new skill or editing an existing one and want it to behave the same way every time: deciding invocation mode, writing a description, choosing what lives in `SKILL.md` versus a linked file, or diagnosing why a skill misfires.
+
+## Cognitive load
+
+The concept the whole reference turns on is **cognitive load** — and its counterpart, **context load**. Every skill spends one or the other:
+
+- A **model-invoked** skill keeps a description in the window every turn, so it costs **context load** but fires on its own.
+- A **user-invoked** skill strips that description; it costs zero context load, but now *you* are the index that has to remember it exists — that's **cognitive load**.
+
+Most of these skills are user-invoked, which is why cognitive load is the pressure the whole system is built to manage: when user-invoked skills multiply past what you can hold in your head, the cure is a **router skill** that names the others and when to reach for each. Once you're thinking in these two loads, most authoring decisions — split or don't, inline or disclose, model- or user-invoked — become the same trade made in different places.
+
+## The other levers
+
+The rest of the reference is the toolkit for spending those loads well:
+
+- **Leading words** — a compact concept already in the model's pretraining (_tight_, _red_, _tracer bullet_) that the agent thinks with while running the skill. It anchors execution *and* invocation in the fewest tokens; hunt restatements that a single word can retire.
+- **Information hierarchy** — the ladder from in-skill step, to in-skill reference, to external reference behind a **context pointer**. **Progressive disclosure** is the move down that ladder so the top stays legible.
+- **Pruning** — single source of truth, relevance, and the no-op test applied sentence by sentence, against **sediment** and **sprawl**.
+- **Failure modes** — **premature completion**, **duplication**, **sediment**, **sprawl**, **no-op** — to diagnose a skill that isn't behaving.
+
+## Where it fits
+
+This is a reach-for-it-anytime standalone reference — the meta-skill you consult while building the rest of the set, not a step in a chain. Its natural neighbour is any router you maintain, because a router is the direct cure for the cognitive load that user-invoked skills pile up; when you're unsure which skill or flow fits a task, [ask-matt](https://aihero.dev/skills-ask-matt) routes you over the whole set.