# Grim Authoring > Author, validate, and package grim-publishable artifacts — skill directories, rule files, agent definitions, MCP server descriptors, and bundle TOMLs. Use when creating or editing an artifact for grim build or grim release; when choosing frontmatter or catalog metadata fields; when adding a vendor-namespaced metadata key for any client grim supports (claude, opencode, copilot, codex, cursor, kiro, junie, gemini, zed, amp, antigravity, cline, droid, goose, warp, openclaw, kilo — one namespace per client name); or when grim build fails validation with exit code 65. - Skill: `grimoire-rs/grim-authoring` (Agent Skill, multi-file: 10 files) - Install (CLI): `npx skillmds@latest add grimoire-rs/grim-authoring` - Raw SKILL.md: https://api.skillmd.com/api/skills/grimoire-rs/grim-authoring/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: AI & ML - License: Apache-2.0 - Author: grimoire-rs (https://skillmd.com/u/grimoire-rs) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/grimoire-rs/grim-authoring --- # Grim Artifact Authoring Grim publishes five artifact kinds to OCI registries. Each has its own source shape, frontmatter schema, and validation gates. This root file holds the invariants that apply to every kind; per-kind depth lives in `references/`, loaded via the routing table below. ## The Five Kinds `grim build` and `grim release` infer the kind from the path — except agents (always `--kind agent`, or they silently pack as rules) and MCP servers (always `--kind mcp`, or the `.toml` is treated as a bundle). | Kind | Source shape | Inference | Installs as | |---|---|---|---| | Skill | Directory with a `SKILL.md` index | directory → skill | Directory tree under the client's `skills/` dir | | Rule | Single `.md` file | `.md` → rule | `rules/.md`, per-client transform | | Rule + support dir | `.md` + sibling `/` dir | sibling dir auto-discovered | Index file + `rules//…` side by side | | Agent | Single `.md`, frontmatter required | **never — `--kind agent` mandatory** | One agent file per client, per-client render | | MCP server | `.toml` descriptor with a `[server]` table | **never — `--kind mcp` mandatory** | Entry in each client's MCP config file, per-client render | | Bundle | `.toml` member list | `.toml` → bundle | Never materializes — expands to its members | ## Which Clients Host Which Kind Grim installs into a growing set of clients, and not every client can host every kind — decide this **before** you author, because it changes what you write. Treat the [enforced matrix][clients] as authoritative; the summary below is a planning aid that the next client can age: - **Skills** are the universal kind — no client declines them, which is why a skill is the portable choice. One scope caveat: OpenClaw is global-scope-only, so a *project* install for it writes nothing. - **Rules** are native for Claude Code, Copilot, Cursor, and Kiro; degraded for OpenCode and Junie (the file installs and grim restates the scope as prose in the body, but nothing enforces it); and **declined** by everyone else — grim warns, skips, and writes no file. Most of the fleet cannot scope instructions: when the audience is broad, a skill reaches clients a rule never will. - **Agents** install for Claude Code, OpenCode, Copilot, Codex, Cursor, Gemini, and Antigravity. Every other client declines them. - **MCP servers** register for the clients that ship a config file grim can splice — Claude, OpenCode, Copilot, Codex, Cursor, Kiro, Junie, Gemini, Zed, Amp, and Antigravity. Only Claude accepts the `ws` transport and the `[server.oauth]` block; every other client skips such a descriptor with a warning. The skills-only clients (and the vendor-neutral `agents` target) write no MCP config at all. A declined kind is an honest refusal, not a silent failure — but it is still zero files. The enforced matrix and the upstream reason behind every degrade and decline: [Client Compatibility][clients]. A `compatibility:` frontmatter field is a human-facing hint only and never overrides it. ## Universal Invariants - Names are `[a-z0-9]` runs joined by single hyphens or periods (`[a-z0-9]+([.-][a-z0-9]+)*`) — non-empty, ≤ 64 chars, no leading or trailing separator, no adjacent separators (`a--b` and `a..b` are invalid). Periods are a grim superset of the Agent Skills standard (`[a-z0-9-]`) — prefer hyphens when portability to strict-standard tooling matters. - A skill's `name` must equal its directory name; an agent's `name` must equal its file stem. Rule names come from the file stem and obey the same character rules. Bundle and MCP names also come from the file stem but are not charset-validated at build; bundle *member* names are validated against the same rules at resolve time. - Any violation of the validated names fails `grim build`/`grim release` with exit code 65. - Unknown top-level frontmatter keys are *preserved* round-trip (forward compatibility) — never rejected, so a typo'd optional key is silent. ## The Metadata-Location Asymmetry Where catalog metadata (`summary`, `keywords`, `repository`, `deprecated`, `replaced-by`, `authors`, `vendor`, `homepage`, `documentation`) is authored differs by kind. This is the #1 authoring confusion — misplaced keys are not errors, they just silently never reach the catalog: | Kind | Catalog metadata keys live… | |---|---| | Skill | inside the `metadata:` map of `SKILL.md` frontmatter | | Agent | inside the `metadata:` map of the agent frontmatter | | Rule | at the **top level** of the rule frontmatter (not in `metadata`) | | MCP server | as **top-level TOML keys**, above the `[server]` table | | Bundle | as **top-level TOML keys**, above the member tables | In every kind, `keywords` is one comma-separated string and `repository` must be an `https://` URL (anything else fails the release with 65). The `deprecated` notice obeys the same per-kind location; an empty or whitespace-only value means *not* deprecated and emits no annotation. `replaced-by` names the successor artifact, authored independently of `deprecated`; its value must parse as a reference or the release fails with 65 — detail in [Publishing][publishing]. `vendor` / `homepage` / `documentation` are derived when omitted — vendor from the release repository's namespace, homepage from `repository`, documentation from `#readme`. `authors` is **not**: the only automatic source is the commit author under `--git`, which publishes a person's name, so author a team name or alias instead — a manifest is readable by anyone who can pull the artifact. Optional in the schema does not mean optional in practice: the set to write on every artifact is [the default six](references/release-checklist.md#metadata-defaults). A skill's top-level `compatibility` is published too, as `com.grimoire.compatibility`. Repository-level support channels (`issues` / `chat` / `contact` / `security`) are **not** artifact metadata — they are authored as a manifest-level `[support]` table in `publish.toml` and ride the mutable description companion, so changing a link needs no re-release. The table fans out to every companion the run pushes; there is no per-entry override and no `grim release` flag. ## Companion: Content Craft This skill covers grim **packaging and validation** only — including build provenance, which is embedded by default at build/release time (`--git` additionally discloses the `origin` remote and commit author; `--no-git` suppresses everything derived); confirm flags with `grim release --help`. For the craft of the content itself — progressive disclosure, context budgets, description triggering, choosing skill vs rule vs agent — read the companion skill `ai-config-authoring` at [`../ai-config-authoring/SKILL.md`](../ai-config-authoring/SKILL.md); both ship together in the `grim-essentials` bundle. When creating a new artifact from scratch, read it FIRST — write good content, then package it here. If that file is missing, install it by identifier: ```sh grim add ghcr.io/grimoire-rs/skills/ai-config-authoring:0 # installs by default # fresh project (no grimoire.toml yet): run `grim init` first ``` ## The Local Dev Loop Iterate on an artifact **before** its first release with local path sources — no registry round-trip: - `grim install ` — **dev-install**: renders the working tree into the clients without declaring anything (`grimoire.toml` and `grimoire.lock` stay untouched). The record is marked `dev` in `grim status`, refreshed by `grim update`, removed by `grim uninstall`. - `grim add ` — declares the local path in the config and pins it by content hash, like any other source. Re-adding over an output you hand-edited in a client is refused as modified; `grim add --force` is the sanctioned overwrite. A path is anything starting `./` or `../`, or absolute. Both commands cover **skills, rules, and agents** only; kind is inferred from the path's shape exactly as `grim build` infers it (directory → skill, bare `.md` → rule, `--kind agent` for agents). A local *bundle* is declared directly in the config's `[bundles]` table instead (`grim add --kind bundle ` refuses with a hint); its members must be registry references — a local bundle has no registry identity to resolve a relative member against. Typical loop: edit → `grim build ` (validation) → `grim install ` (see it in a real client) → repeat → release. Confirm flags with `grim install --help`. ## Routing Table | Read… | …when | |---|---| | [references/skill-spec.md](references/skill-spec.md) | Authoring a skill directory or its `SKILL.md` frontmatter | | [references/rule-spec.md](references/rule-spec.md) | Authoring a rule file, its globs, or a support directory | | [references/agent-spec.md](references/agent-spec.md) | Authoring an agent definition or its vendor overrides | | [references/mcp-spec.md](references/mcp-spec.md) | Authoring an MCP server descriptor or its env references | | [references/bundle-spec.md](references/bundle-spec.md) | Authoring a bundle TOML or choosing pinning strategy | | [references/vendor-metadata.md](references/vendor-metadata.md) | Adding a key in a reserved `.*` namespace — one per client name (`claude.*`, `opencode.*`, `copilot.*`, `codex.*`, `cursor.*`, `kiro.*`, `junie.*`, `gemini.*`, `zed.*`, `amp.*`, `antigravity.*`, `cline.*`, `droid.*`, `goose.*`, `warp.*`, `openclaw.*`, `kilo.*`) | | [references/release-checklist.md](references/release-checklist.md) | Before `grim release`/`grim publish`, the metadata every package should set, repository-path layout, batch manifests, description companions, or triaging an exit-65 failure | | [references/bootstrap-existing-repo.md](references/bootstrap-existing-repo.md) | Turning an existing skill repo (agentskills.io `skills//SKILL.md` or `.claude/skills/`) into a grim publisher — inventorying artifacts, fixing names, backfilling catalog metadata, wiring publish CI | | [references/updating.md](references/updating.md) | Maintaining this skill package itself | ## Schema Authority This skill teaches the craft and the pitfalls; the authoritative schema reference is the Grimoire docs site. When a field table here feels incomplete, the docs page is the source of truth: [Artifact Reference][artifacts] · [Vendor-Specific Metadata][vendor] · [Publishing][publishing] · [Agent Artifacts][agents] · [Client Compatibility][clients]. For the TOML surfaces, `grim schema --kind ` prints the JSON Schema generated from grim's own parsers — bind it in your editor to catch manifest typos before any command runs. ## Verify Before Acting `grim build ` validates without pushing — run it after every edit; its output is ground truth for the grim version actually installed. On any conflict between this skill and `grim build` output or `grim --help`, trust the tool. Treat this skill as the map, not the territory. --- Verified against the grim release this package ships beside. [artifacts]: https://grimoire.rs/artifacts.html [vendor]: https://grimoire.rs/vendor-metadata.html [publishing]: https://grimoire.rs/publishing.html [agents]: https://grimoire.rs/agents.html [clients]: https://grimoire.rs/clients.html