docs(skills): add game-prep skill

Lists what a game package requires and how to validate it, matching
the checks journal check performs.

.agents/skills/game-prep/SKILL.md

@@ -0,0 +1,110 @@
+---
+name: game-prep
+description: Prepare or validate a game package under games/ for this solo journaling workspace. Use when adding a new game system, porting one from games/generic/, reviewing whether a game package is complete, or checking that its rules, tables, character backgrounds, and commands are wired up correctly before starting a campaign.
+---
+
+# Preparing a game package
+
+A game package is a directory under `games/<id>/` that holds everything true
+about a game *before* play starts: its rules, spark tables, character options,
+and tool scripts. Campaigns own the play state and reference a game by id from
+`campaigns/<name>/campaign.md` frontmatter (`game: <id>`).
+
+Read `docs/games.md` for the full contract. `games/generic/` is the reference
+implementation — copy it as a starting point.
+
+Rule of thumb: a game is what is true before play, a campaign is what play
+changes. Never copy game content into a campaign; reference it.
+
+## Required contents
+
+| Path | Required | Purpose |
+|------|----------|---------|
+| `package.json` | yes | `@solo/game-<id>`, `"type": "module"`, `main`/`exports`; depend on `@solo/oracle` if scripts use dice or tables |
+| `index.js` | yes | default-export manifest: `id`, `title`, `description`, `rules`, `commands` |
+| `game.md` | yes | authoritative rules the agent reads each session |
+| `tables/*.csv` | yes | spark and complication tables, header `min,max,text[,tags]` |
+| `characters/` | yes | backgrounds, playbooks, starting options — the character *options*, not the PC |
+| `rules/` | recommended | longer rulebook chapters, read on demand |
+| `scripts/` | optional | standalone tool scripts for one-off jobs |
+
+Details that trip people up:
+
+- **The directory name is the game id.** Keep the manifest's `id` and the
+  package name `@solo/game-<id>` in sync with it.
+- **Ship a `complication-themes.csv`.** `journal oracle --complicate` resolves
+  that table name, and without it on either the campaign or the game the roll
+  fails. There is no cross-game fallback.
+- **Tables must be contiguous and non-overlapping.** `min`/`max` are inclusive
+  integers and define the die range; every integer in the table's span should be
+  covered exactly once. Quote any `text` containing a comma.
+- **Commands** are declared in `index.js` as `commands: { name: { description, run } }`
+  and exposed as `journal <name>`. Handlers receive `(args, ctx)` where `args` is
+  `{ positional, flags }` and `ctx` carries `findTable` plus the shared helpers.
+- **Run `pnpm install`** after adding the `@solo/oracle` dependency or creating a
+  new package, so the workspace symlink exists.
+
+## Preparation workflow
+
+1. Copy the reference: `games/generic/` → `games/<id>/`.
+2. Edit `package.json`: set `name` to `@solo/game-<id>` and a real description.
+3. Edit `index.js`: set `id`, `title`, `description`; replace or remove the
+   example command.
+4. Write `game.md`: resolution, stats, tracks and conditions, character
+   creation, and the tables the game provides.
+5. Add tables to `tables/`, one CSV per table, ranges contiguous.
+6. Add character options to `characters/` — rollable ones as CSV, prose as
+   markdown.
+7. Add `rules/` chapters for anything too long for `game.md`.
+8. Add tooling: preferred path is a `commands` entry in `index.js` for anything
+   the agent calls during play; standalone one-off scripts go in `scripts/`.
+9. `pnpm install`.
+10. Validate (below) before starting a campaign.
+
+## Validation
+
+Run all of these. Each proves something the others do not.
+
+| Command | Proves |
+|---------|--------|
+| `pnpm install` | the `@solo/oracle` workspace link resolves |
+| `pnpm journal check --game <id>` | `package.json` parses and is named right, `index.js` loads, the rules file exists, tables parse and are contiguous, `tables/` and `characters/` exist |
+| `pnpm journal games` | the game appears in the catalog; a manifest that throws shows as `ERROR:` |
+| `pnpm journal game <id>` | rules path, table count, characters path, and the command list all resolve |
+| `pnpm journal roll <table> --game <id>` | each table rolls and its range resolves |
+| `pnpm journal <command> --game <id>` | each game command runs |
+
+`journal check` exits non-zero on errors. It reports:
+
+- **errors** — overlapping table ranges, CSV parse failures, invalid or missing
+  `package.json`, missing game.
+- **warnings** — range gaps, package name mismatch, missing `"type": "module"`,
+  missing `index.js`/`tables/`/`characters/`, missing rules file.
+
+Fix every error, then work the warnings down to zero. The checks live in
+`packages/cli/src/cli.js` (`checkGamePackage`, `checkTablesDir`).
+
+## Definition of done
+
+- [ ] `games/<id>/` exists; directory name, manifest `id`, and package name agree.
+- [ ] `pnpm journal check --game <id>` exits 0 with no errors.
+- [ ] `pnpm journal games` lists it without `ERROR`.
+- [ ] `pnpm journal game <id>` shows the rules path and every intended command.
+- [ ] Every table rolls cleanly and its ranges are contiguous.
+- [ ] `game.md` covers resolution, stats, tracks, character creation, and the
+  game's tables.
+- [ ] `characters/` holds the character options.
+- [ ] A complication table is present if the game uses `--complicate`.
+- [ ] `pnpm journal new-campaign scratch --game <id>` succeeds (then remove the
+  scratch campaign).
+
+## Common failures
+
+- **Overlapping ranges** — e.g. rows `1-3` and `3-6` both cover 3. Error.
+- **Gaps** — e.g. rows `1-2` and `4-6` leave 3 uncovered. Warning.
+- **Unquoted comma** in a table's `text` shifts the columns; wrap it in quotes.
+- **`ERR_MODULE_NOT_FOUND: @solo/oracle`** — the dependency was added but
+  `pnpm install` was not run.
+- **Manifest id drifting** from the directory name — `journal game <id>` still
+  works (the directory wins), but the package is inconsistent and the docs
+  become misleading.