chore: add writing-changesets AI skill

Author: aspiers

.claude/skills/writing-changesets/SKILL.md

@@ -0,0 +1,100 @@
+---
+name: writing-changesets
+description: Create changeset files for user-facing changes. Use when making schema changes, modifying types, or any change that affects package consumers.
+---
+
+# Writing Changesets
+
+Create a changeset file to document user-facing changes for release.
+
+## When to Use
+
+Add a changeset when making changes that affect consumers:
+
+- Adding new lexicons
+- Modifying existing lexicon schemas (breaking or non-breaking)
+- Changing TypeScript type exports
+- Renaming any exported constants, types, or functions
+- Modifying generation scripts that affect exported code
+- Any change that requires a version bump or affects package consumers
+
+Skip changesets for internal changes (build scripts, documentation only).
+
+## Format
+
+Create in `.changeset/` a Markdown file with a descriptive name (e.g.,
+`add-attachment-outcome-types.md`) in this format:
+
+```markdown
+---
+"@hypercerts-org/lexicon": minor
+---
+
+Add new attachment and outcome record types to support rich media claims
+```
+
+### Frontmatter Fields
+
+There should be a frontmatter field for each package being changed.
+The field name should be the package name, and the field value should
+be one of the following change types:
+
+- `patch` - Bug fixes, non-breaking changes
+- `minor` - New features, non-breaking additions (also breaking
+  changes if the version in `package.json` is still 0.x.y)
+- `major` - Breaking changes (_ONLY_ use if the version in `package.json`
+  is already greater than 0.x.y)
+
+### Description
+
+In the body after the frontmatter field(s), write a clear, concise
+description following conventional commit style. Focus on what changed
+and why.
+
+## Example Changesets
+
+**New lexicon type:**
+
+```markdown
+---
+"@hypercerts-org/lexicon": minor
+---
+
+Add attachment record type for supporting rich media evidence on claims
+```
+
+**Schema change:**
+
+```markdown
+---
+"@hypercerts-org/lexicon": minor
+---
+
+Convert location field to locations array across activity, evaluation, and measurement records
+```
+
+**Breaking change when package version is 1.x.y:**
+
+```markdown
+---
+"@hypercerts-org/lexicon": major
+---
+
+Rename evidence record to attachment and outcome, requiring migration of existing records
+```
+
+**Breaking change when package version is 0.x.y:**
+
+```markdown
+---
+"@hypercerts-org/lexicon": minor
+---
+
+Rename evidence record to attachment and outcome, requiring migration of existing records
+```
+
+## Key Files
+
+- `.changeset/config.json` - Changeset configuration
+- Existing changeset files in `.changeset/` - Reference for naming and format
+- `package.json` - Contains version and release scripts

AGENTS.md

@@ -265,22 +265,23 @@ npm run check
 - The `.prettierignore` excludes `generated/` and `dist/` since they're auto-generated
 - The `.gitignore` excludes `generated/` and `dist/` to keep the repo clean
 
+## Changesets
+
+This repository uses
+[Changesets](https://github.com/changesets/changesets) for versioning.
+
 ### ⚠️ CHANGESET REQUIREMENTS (MANDATORY)
 
 **AI agents MUST create a changeset file** for ANY of the following changes:
 
-- ✅ Adding new lexicons
-- ✅ Modifying existing lexicon schemas (breaking or non-breaking)
-- ✅ Changing TypeScript type exports
-- ✅ Renaming any exported constants, types, or functions
-- ✅ Modifying generation scripts that affect exported code
-- ✅ Any change that requires a version bump or affects package consumers
-
-**How to create a changeset** (AI agents):
+- Adding new lexicons
+- Modifying existing lexicon schemas (breaking or non-breaking)
+- Changing TypeScript type exports
+- Renaming any exported constants, types, or functions
+- Modifying generation scripts that affect exported code
+- Any change that requires a version bump or affects package consumers
 
-1. Create a new `.md` file in `.changeset/` directory
-2. Use format shown in "Versioning" section
-3. DO NOT use the interactive `npm run changeset` command
+Use the `writing-changesets` skill for writing changesets.
 
 **Example scenarios requiring changesets:**