feat(metadata|docs): reusable tag groups with $group: (#5037)

* feat(metadata): reusable tag groups with `$group:`

A `$group:<group-name>` marker in `tags` is replaced in place with the tags of
`groups/<group-name>.json`: a small set of tags for what a variant suffix
means, such as `-minus` → remove, delete.

- Read groups in `readGroups` and resolve markers next to `$extends:`,
  failing on unknown groups and on `$group:` outside `tags`
- Add `group.schema.json` and lint, spell-check and format `groups/*.json`
- `pnpm checkIcons` also fails on literals a group already provides, and
  warns about icons that list a group's tags by hand and unused groups
- Add the `minus`, `plus` and `x` groups and use them in
  `alarm-clock-minus`, `file-minus`, `file-plus` and `file-x`

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Fix group checker

* Apply batched suggestions from code review

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* feat(metadata): reusable tag groups with `$group:`

A `$group:<group-name>` marker in `tags` is replaced in place with the tags of
`groups/<group-name>.json`: a small set of tags for what a variant suffix
means, such as `-minus` → remove, delete.

- Read groups in `readGroups` and resolve markers next to `$extends:`,
  failing on unknown groups and on `$group:` outside `tags`
- Add `group.schema.json` and lint, spell-check and format `groups/*.json`
- `pnpm checkIcons` also fails on literals a group already provides, and
  warns about icons that list a group's tags by hand and unused groups
- Add the `minus`, `plus` and `x` groups and use them in
  `alarm-clock-minus`, `file-minus`, `file-plus` and `file-x`

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Fix group checker

* Apply batched suggestions from code review

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* feat(metadata): reusable tag groups with `$group:`

A `$group:<group-name>` marker in `tags` is replaced in place with the tags of
`groups/<group-name>.json`: a small set of tags for what a variant suffix
means, such as `-minus` → remove, delete.

- Read groups in `readGroups` and resolve markers next to `$extends:`,
  failing on unknown groups and on `$group:` outside `tags`
- Add `group.schema.json` and lint, spell-check and format `groups/*.json`
- `pnpm checkIcons` also fails on literals a group already provides, and
  warns about icons that list a group's tags by hand and unused groups
- Add the `minus`, `plus` and `x` groups and use them in
  `alarm-clock-minus`, `file-minus`, `file-plus` and `file-x`

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Fix group checker

* Apply batched suggestions from code review

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* feat(metadata): reusable tag groups with `$group:`

A `$group:<group-name>` marker in `tags` is replaced in place with the tags of
`groups/<group-name>.json`: a small set of tags for what a variant suffix
means, such as `-minus` → remove, delete.

- Read groups in `readGroups` and resolve markers next to `$extends:`,
  failing on unknown groups and on `$group:` outside `tags`
- Add `group.schema.json` and lint, spell-check and format `groups/*.json`
- `pnpm checkIcons` also fails on literals a group already provides, and
  warns about icons that list a group's tags by hand and unused groups
- Add the `minus`, `plus` and `x` groups and use them in
  `alarm-clock-minus`, `file-minus`, `file-plus` and `file-x`

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Fix group checker

* Apply batched suggestions from code review

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

.github/instructions/groups.instructions.md

@@ -0,0 +1,29 @@
+---
+applyTo: "groups/*.json"
+---
+# Groups
+
+A group is a small, reusable set of tags for **one icon variant** — the modifier suffix in an icon name, such as `-plus`, `-check` or `-off`. Icons reference a group with a `"$group:<group-name>"` marker inside their `tags` array, and the marker is replaced at build time with the group's tags.
+
+The file name without `.json` is the group name: the variant suffix it belongs to (`plus` for `file-plus`, `question-mark` for `file-question-mark`), in lowercase kebab-case. Each file has a `$schema`, a one-line `description` saying which meaning the group covers, and a non-empty `tags` array.
+
+```json
+{
+  "$schema": "../group.schema.json",
+  "description": "Action: removing or deleting something",
+  "tags": ["remove", "delete"]
+}
+```
+
+## Rules
+
+- **One group per variant.** Name the group after the variant suffix (`plus`, `minus`, `check`, `cog`), so `file-plus` uses `$group:plus` and `alarm-clock-minus` uses `$group:minus`.
+- **Different suffixes with the same meaning share one group.** Do not create a second group for a synonym: `-warning` and `-exclamation-point` use `$group:alert`. When a meaning is spread over many suffixes, name the group after the meaning instead: every currency suffix (`-euro`, `-dollar-sign`, `-japanese-yen`…) uses `$group:currency`.
+- **Tags describe what the variant means, not its glyph.** `plus` holds `add`, `new`, `create`; `cog` holds `settings`, `gear`. Do not put the suffix itself (`plus`, `cog`, `lock`) in a group: tags must not repeat the icon name.
+- **Keep groups small and generic.** Only tags that hold for *every* icon that uses the group. If a tag is true for just some of them, it belongs on those icons as a literal.
+- **Not every icon with the suffix uses the group.** `-off` means "disabled" on `wifi-off` but "allergy free" on `wheat-off`, and `-x` means "delete" on `file-x` but "mute" on `volume-x`. Only icons where the variant carries the group's meaning use the marker; the others keep literal tags.
+- **Do not add a group before it is used.** `pnpm checkIcons` warns about groups no icon references.
+- **Groups do not nest.** A group's `tags` are literal tags only — no `$extends:` or `$group:` markers.
+- Tags are lowercase, and follow the same conventions as icon tags.
+
+Run `pnpm run lint:json:groups` to validate the files against the schema, and `pnpm checkIcons` to check how icons use them.

.github/instructions/metadata.instructions.md

@@ -25,7 +25,7 @@ Some icons are variants of another icon (for example `alarm-clock-minus` is an `
 
 ```jsonc
 {
-  "tags": ["$extends:alarm-clock", "remove"],
+  "tags": ["$extends:alarm-clock", "$group:minus"],
   "categories": ["$extends:alarm-clock"],
   "contributors": ["$extends:alarm-clock", "some-user"]
 }
@@ -35,14 +35,36 @@ When checking or adding a `$extends:` marker:
 
 - A marker must be exactly `"$extends:"` followed by the name of an **existing** icon — one that has its own `icons/<icon-name>.json` and `icons/<icon-name>.svg`. The icon name is the file name without the `.json` extension, written in lowercase kebab-case. Referencing a non-existent icon is invalid.
 - Markers are only supported inside the `tags`, `categories`, and `contributors` arrays. They are not a separate property.
-- Only use `$extends:` for the icon's **base icon** — the thing the icon _is_ (`file-plus` is a `file`, `alarm-clock-minus` is an `alarm-clock`). Never extend a **modifier** icon such as `plus`, `minus`, `x` or `check`: their tags describe that glyph on its own (`minus` carries `divider`, `hr`, `markdown`, `separator`…), which makes no sense on an alarm clock. Add the modifier's meaning as literal tags instead.
+- Only use `$extends:` for the icon's **base icon** — the thing the icon _is_ (`file-plus` is a `file`, `alarm-clock-minus` is an `alarm-clock`). Never extend a **modifier** icon such as `plus`, `minus`, `x` or `check`: their tags describe that glyph on its own (`minus` carries `divider`, `hr`, `markdown`, `separator`…), which makes no sense on an alarm clock. Use a group for the modifier's meaning instead.
 - An icon may not extend itself, and circular chains (A extends B, B extends A) are not allowed.
 - Ordering is preserved: inherited values are inserted at the marker's position, so place `$extends:` markers where the inherited values should appear (conventionally first, before the icon's own literal values).
 - Run `pnpm checkIcons` to validate all references. It fails on missing icons, self-references, and circular dependencies. Do not assume a marker is valid without confirming the target icon exists.
 
+## Groups
+
+`$extends:` says what an icon **is**; `$group:` says what its variant suffix (`-plus`, `-check`, `-off`…) **means**. A `"$group:<group-name>"` marker inside `tags` is replaced, in place, with the tags of `groups/<group-name>.json`.
+
+```jsonc
+{
+  // `file-minus` is a file, and its `-minus` variant means "remove"
+  "tags": ["$extends:file", "$group:minus", "erase"],
+  "categories": ["$extends:file"]
+}
+```
+
+When checking or adding a `$group:` marker:
+
+- A marker must be exactly `"$group:"` followed by the name of an existing file in `groups/`, without the `.json` extension, in lowercase kebab-case.
+- `$group:` is allowed **only** inside `tags`. It is not valid in `categories` or `contributors`.
+- Groups are named after the variant suffix: `file-plus` uses `$group:plus`, `file-question-mark` uses `$group:question-mark`. Suffixes with the same meaning share a group: `mail-warning` uses `$group:alert`, and every currency suffix uses `$group:currency`.
+- The same suffix can mean different things in different contexts — `-off` means "disabled" on `wifi-off` but "allergy free" on `wheat-off` — so only use the group when the icon carries the group's meaning, and keep context-specific tags as literals.
+- Do not repeat a tag a group already provides, and do not use the same group twice in one array.
+- Conventional order: the `$extends:` base icon first, then `$group:` markers, then the icon's own literal tags.
+- Run `pnpm checkIcons` to validate the markers. It fails on unknown groups, on `$group:` outside `tags`, and on literals that a marker already provides.
+
 ## There should not be duplicates
 
-Never list a value that a `$extends:` marker already provides. Before adding a literal `tag`, `category`, or `contributor`, look at the referenced icon's metadata: if that icon already contains the value, do not also add it as a literal entry in the same array — the inherited value already covers it. For example, if `alarm-clock` already has the tag `morning`, an icon that uses `"$extends:alarm-clock"` in its `tags` must **not** also list `"morning"`.
+Never list a value that a `$extends:` or `$group:` marker already provides. Before adding a literal `tag`, `category`, or `contributor`, look at the referenced icon's metadata: if that icon already contains the value, do not also add it as a literal entry in the same array — the inherited value already covers it. For example, if `alarm-clock` already has the tag `morning`, an icon that uses `"$extends:alarm-clock"` in its `tags` must **not** also list `"morning"`.
 
 Likewise, do not reference the same icon more than once in a single field (no duplicate `$extends:` markers), and do not repeat literal values. The `tags`, `categories`, and `contributors` arrays must contain only unique entries (`uniqueItems` in `icon.schema.json`), and after extends resolution the final arrays must not contain any duplicates.
 

.github/labeler.yml

@@ -23,6 +23,7 @@
       - any-glob-to-any-file:
           - 'icons/*.json'
           - categories/*
+          - groups/*
 
 # For changes or added icons
 🎨 icon:

.github/workflows/linting-icons.yml

@@ -8,6 +8,7 @@ on:
     paths:
       - 'icons/*'
       - 'lab/*'
+      - 'groups/*'
 
 permissions: {}