The registry index and .hpack

Level: preview (stability.md). Schema 1.

index.json

{
  "schema": 1,
  "generated": "2026-10-24T18:00:00Z",
  "projects": [{
    "id": "coords_hud", "kind": "mod", "name": "Coordinates HUD", "summary": "One line.",
    "description": "Markdown.", "authors": ["Horizon"], "owners": ["ludovic111"],
    "license": "MIT", "source": "https://github.com/...", "icon": "https://...png", "key": "RWT...", "downloads": 1234,
    "versions": [{
      "version": "0.1.0", "published": "2026-10-24", "changelog": "",
      "api": "0.1", "side": "client", "capabilities": ["game-read", "hud", "chat"], "api_level": 0, "game": "26.3",
      "file": { "name": "coords_hud-0.1.0.hmod", "url": "https://github.com/ludovic111/horizon-mods/releases/download/...",
                "size": 438, "sha256": "e113...", "signature": "untrusted comment: ...\n...\ntrusted comment: ...\n...\n" }
    }]
  }],
  "revoked": [{ "id": "bad_mod", "sha256": "1111...", "reason": "Sent chat messages it didn't declare.", "date": "2026-10-24" }]
}

Readers ignore fields they don't know, so an optional field can be added to schema 1. Renaming or removing a field, or changing what one means, makes schema 2.

Before a file is installed

index::check_file runs on the downloaded file, before it reaches the game folder:

1. Its size and SHA-256 are the ones the entry lists, and it isn't revoked.
2. With a project key: its signature verifies with that key (minisign's prehashed and legacy signatures both).
3. What the file says matches the entry: a mod's horizon-mod.toml (id, version, API, side, capabilities), its API level when the entry lists one, and its content's fence (mods.md); a modpack's manifest (id, version, format, game, mods); a resource pack's pack.mcmeta; a shader pack's horizon_shader_api::check and manifest (id, version, shader API).
4. A kind this build can't install is refused with "this Horizon can't install a … yet".

The game still checks a mod's component imports against its capabilities when it starts it, as for any mod.

.hpack

A zip holding horizon-modpack.toml and, optionally, overrides/. The mods are not inside: the launcher downloads each from the index and checks it as above.

format = 1
id = "cozy"                 # [a-z0-9_]{1,64}: the profile's folder
name = "Cozy"
version = "1.0.0"
description = "Coordinates and a calm render distance."
authors = ["Horizon"]
game = "26.3"

[[mods]]
id = "coords_hud"
version = "0.1.0"
sha256 = "e1135345692f6dd8fd4c51920151944b82333e17049c9bb7d756f27b8deefc53"
on = true                   # optional, default true: turned on in the profile's horizon-mods.txt

Unknown keys are refused. overrides/ may hold only options.txt, horizon-graphics.txt, horizon-extras.txt, resourcepacks/<name>.zip and horizon-mods/.horizon-mod-data/<a listed mod>/... (a mod's own saved settings, capability storage), each at most 64 MiB and 256 MiB in all; anything else refuses the pack. The launcher copies them into the profile's game folder.

The registry repository

ludovic111/horizon-mods holds one mods/<id>.toml per project, written by the submission form or by hand, and revoked.toml. What an entry can't vouch for is read from its file by the kind's own check (index::inspect): a mod's API, side and capabilities, a modpack's mods, the size. Types and rules: horizon_mods::index::registry.

id = "coords_hud"                # the file's name, and the manifest's id
kind = "mod"                     # mod | modpack | resourcepack | shader
name = "Coordinates HUD"
summary = "One line, at most 160 characters."
description = """Markdown."""    # optional
authors = ["Horizon"]
owners = ["ludovic111"]          # GitHub logins who may publish updates
license = "MIT"
source = "https://github.com/..."
icon = "icons/coords_hud.png"    # optional: a PNG of at most 256 KiB in the repository, or https://
key = "RWT..."                   # optional: the minisign public key every version is signed with

[[versions]]                     # newest first
version = "0.1.0"                # letters, digits, '.', '-', '_': the release tag is <id>-<version>
published = "2026-10-24"
game = "26.3"
file = "coords_hud-0.1.0.hmod"   # the name players download
sha256 = "e113..."               # pins the reviewed file
signature = """untrusted comment: ..."""   # when the project has a key
changelog = ""                   # optional

# revoked.toml
[[revoked]]
id = "bad_mod"
sha256 = "1111..."               # optional: without it, every version
reason = "Sent chat messages it didn't declare."
date = "2026-10-24"

The submission form's service (crates/horizon-mod-registry) writes these entries: it signs the creator in with GitHub, runs the file's checks, uploads the file to the repository's staging release as <sha256>.<extension> and opens the pull request. Only an entry's owners publish updates through it.

Unknown keys are refused. Its CI runs cargo-horizon-mod (crates/cargo-horizon-mod):

How the repository runs (its workflows are in .github/workflows/):

• A pull request (check.yml) runs registry review, downloads each new file from the staging prerelease, runs registry check on it and builds the index it would publish; the report is the run's summary. The tool is cargo-horizon-mod from Horizon at the commit in the repository variable HORIZON_REV. The form's pull requests are opened with the token of the account in the variable REGISTRY_BOT; for those, the author is the login in the body's <!-- submitted-by: … --> line.
• Merging needs the check run and a CODEOWNER's review. publish.yml then makes each new version a release <id>-<version> and deploys index.json and icons/ to GitHub Pages: https://ludovic111.github.io/horizon-mods/index.json, served with Access-Control-Allow-Origin: *.
• Weekly, cleanup.yml deletes staged copies of published files after 7 days and of files no open pull request lists after 30.
• Taking a file down is a pull request adding it to revoked.toml. Removing an entry outright (a test, a project nobody installed) fails registry review on purpose and needs an administrator's merge.

Kinds open to submissions: mod, modpack, resourcepack, shader. A shader pack (.hshader) passes horizon_shader_api::check, the check the game runs before it loads one (horizon-shader check, shaders.md): every stage validated by naga and translated for Vulkan, Metal and DirectX 12; its manifest's id, version and shader API line are its facts. Iris and OptiFine packs are for the Modrinth browser. A new kind gets its own check before it opens.

Changelog

• 2026-10-26: projects[].downloads, GitHub's download counts of a project's files, refreshed every hour.
• 2026-10-26: the launcher installs shader files into shaderpacks/; the sample index lists one (glow).
• 2026-10-25: shader opens, checked by horizon_shader_api::check; its files are .hshader.
• Schema 1 (2026-10-24): kinds mod, modpack, resourcepack, shader; .hpack format 1.