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Sanity Migration

SanityOfficialPublished by Sanity

  • Skill
  • Tool integration
  • Software development
  • MIT
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From the author

Plans, implements, and reviews migrations from other CMSes and content systems into Sanity. Use when migrating or replatforming to Sanity from AEM, Adobe Experience Manager, Contentful, Strapi, Webflow, WordPress, Payload, Drupal, Markdown/MDX/frontmatter files, WXR/XML exports, CMS APIs, database dumps, static HTML, or when designing extraction, transformation, Portable Text conversion, asset migration, redirects, validation, and cutover workflows.
— the description by Sanity

AutoGineer summary

Written by AutoGineer from the skill’s own files, not by the author

This skill provides a systematic approach to migrating content from various CMS platforms into Sanity. It treats migration as an ETL (Extract, Transform, Load) project, emphasizing deterministic scripts, content modeling, and validation over manual operations. The skill includes specific guidance for platforms such as AEM, Contentful, Strapi, Webflow, WordPress, Payload, Drupal, and Markdown-based systems, ensuring that content is properly mapped, transformed into Portable Text, and validated before final cutover.

What it does

  • Provides a structured workflow for planning and executing CMS-to-Sanity migrations.
  • Offers platform-specific guidance for extracting data from common CMS environments.
  • Defines best practices for mapping source content to Sanity schemas and Portable Text.
  • Requires the creation of migration plans, content inventories, and validation reports.
  • Encourages the use of deterministic scripts for repeatable and reliable data imports.
  • Includes procedures for handling assets, redirects, and final cutover synchronization.

When to use it

  • When replatforming a website or application to use Sanity as the content backend.
  • When moving content from legacy systems like AEM, Drupal, or WordPress.
  • When migrating static files like Markdown or MDX into a structured CMS.
  • When you need to perform a complex data transformation and cleanup during an import.
  • When you need to ensure data integrity through validation checks and delta syncs.

Advantages

  • Reduces risk by mandating planning and validation steps before execution.
  • Promotes repeatable migrations through script-based ETL patterns.
  • Ensures content is modeled for Sanity's capabilities rather than just copied.
  • Provides clear paths for handling complex data like rich text and assets.
  • Supports iterative development through deterministic ID management.

Usage examples

“I need to migrate my site from Contentful to Sanity. Where do I start?”
The agent will guide you through the Contentful-specific extraction process, help you plan your content mapping, and suggest using the contentful-to-sanity toolkit for an initial pass.
“How should I handle AEM content fragments during a migration?”
The agent will provide instructions on using AEM GraphQL to extract fragments and mapping them to Sanity document types or page builder blocks.
“Create a migration plan for my WordPress site.”
The agent will outline the steps to export WXR data, map WordPress posts to Sanity schemas, convert HTML to Portable Text, and set up redirects.

Install

  1. Download the skill as a ZIP:

    https://mp-staging.autogineer.com/agent-skills/sanity-io/sanity-migration/download

  2. Unzip it into the cross-client skills folder of your project:

    mkdir -p .agents/skills && unzip sanity-migration.zip -d .agents/skills

Documentation by Sanity

Sanity Migration

Use this skill for CMS-to-Sanity migration work. Treat migration as a content strategy and ETL project, not a blind lift-and-shift.

Required Workflow

  1. Read references/general.md first.

  2. If the source platform is known, also read its guide:

    • AEM / Adobe Experience Manager: references/aem.md

    • Contentful: references/contentful.md

    • Strapi: references/strapi.md

    • Webflow: references/webflow.md

    • WordPress / WXR / Elementor: references/wordpress.md

    • Payload: references/payload.md

    • Drupal: references/drupal.md

    • Markdown / MDX / frontmatter files: references/markdown.md

  3. Before writing code, produce a short migration plan covering source access, content scope, schema decisions, extraction, transformation, import, validation, redirects, and cutover.

  4. Prefer deterministic, repeatable scripts for real migrations. Write and review migration scripts, mappings, and validation checks; do not rely on one-off content operations for large content volumes.

Deliverables to Produce

For implementation or planning tasks, produce these artifacts or explain why they are not needed:

  • Content inventory: source types, counts, locales, status/draft scope, assets, and relationship types.

  • Source-to-Sanity mapping: document types, object types, references, Portable Text fields, asset fields, IDs, and skipped content.

  • Extraction approach: credentials/access needed, API/export commands, raw snapshot location, and known blind spots.

  • Transform/import plan: deterministic IDs, write order, asset handling, rich text conversion, validation, and rerun strategy.

  • Cutover plan: delta sync/content freeze, redirects, broken-link checks, SEO metadata, and manual cleanup.

Defaults

  • Use stable document IDs derived from source IDs, slugs, paths, or hashes.

  • Use createOrReplace, createIfNotExists, or sanity datasets import --replace so reruns converge.

  • Snapshot extracted source data to disk before transforming it.

  • Import or create referenced documents before documents that reference them.

  • Convert rich text to Portable Text instead of storing raw HTML or Markdown strings.

  • Upload assets to Sanity or the Media Library; do not leave production content dependent on legacy CDN URLs.

  • Track per-document quality issues and produce a validation summary before cutover.

  • Preserve legacy URLs and source IDs for redirects, QA, and future debugging.

Sanity Guardrails

  • Model what content is, not how the old site rendered it.

  • Use documents for reusable or independently managed entities; use objects for content owned by one document.

  • Use defineType, defineField, and defineArrayMember if authoring Sanity schemas.

  • Use image/file fields with uploaded Sanity assets or Media Library assets, not legacy CDN URLs.

  • Use Portable Text arrays for rich text and custom blocks; do not store raw HTML as the canonical body.

  • Run schema extraction and TypeGen after schema or GROQ query changes when the project uses TypeScript.

  • Deploy or apply schema changes before using MCP/content tools against the target dataset.

For deeper Sanity implementation guidance, use sanity-best-practices if it is already available. If it is not installed, tell the user they can add it with:

npx skills add sanity-io/agent-toolkit --skill sanity-best-practices

Stop and Ask

Stop before coding when any of these are unclear:

  • Source access path, credentials, export file, or database connection.

  • Target Sanity project/dataset or whether a scratch dataset should be used.

  • Draft, archived, scheduled, locale, or version history scope.

  • Whether media files should be migrated and whether asset URLs/files are accessible.

  • Whether the destination schema exists or should be designed as part of the migration.

Do Not Do This

  • Do not create random IDs for source-backed documents.

  • Do not fetch-then-create referenced documents; use deterministic IDs and createIfNotExists/createOrReplace.

  • Do not run bulk migrations through MCP content tools when NDJSON or scripts are appropriate.

  • Do not flatten locale fallback values into translations unless requested.

  • Do not leave TODOs for required media, authors, references, or rich text conversion.

  • Do not declare a migration done without count checks, sample checks, reference checks, and route/redirect checks.

Reference Map

Use references/general.md for shared migration principles and the platform references for source-specific extraction routes, modeling traps, and validation checks.

For source systems not explicitly covered, apply references/general.md and adapt the closest platform pattern:

  • API-first CMSes: start from Contentful, Strapi, or Payload.

  • Monolithic/page-builder systems: start from WordPress, Drupal, Webflow, or AEM.

  • HTML-heavy exports: start from the WordPress and Webflow rich-text guidance.

  • Markdown-first sources: start from references/markdown.md.

Files

references/markdown.md

Markdown to Sanity

What to Determine First

Before writing migration code, determine:

  • Source shape: Markdown files, MDX, GitHub README-style content, static-site content, AI-generated Markdown, or Markdown exported from a CMS.

  • File count, directory structure, and whether paths encode slugs, dates, sections, or locales.

  • Frontmatter fields and formats.

  • Markdown extensions: GFM tables, callouts, directives, footnotes, raw HTML, code fences, embeds, local images, and MDX JSX.

  • Target Sanity document type and Portable Text field name.

  • Allowed Portable Text styles, lists, decorators, annotations, and custom object types.

  • Whether tags, authors, categories, and images are references, inline fields, or separate documents.

Default Conversion Path

Use direct Markdown -> Portable Text conversion with @portabletext/markdown.

npm install @portabletext/markdown
import {markdownToPortableText} from '@portabletext/markdown'

const body = markdownToPortableText(markdown)

Do not call Markdown -> HTML -> htmlToBlocks "direct conversion." That is an HTML fallback path. Use it only when the Markdown pipeline cannot handle source-specific syntax that is easier to normalize as HTML.

Schema-Constrained Conversion

For a Sanity block array schema, convert it with @portabletext/sanity-bridge:

npm install @portabletext/markdown @portabletext/sanity-bridge
import {markdownToPortableText} from '@portabletext/markdown'
import {sanitySchemaToPortableTextSchema} from '@portabletext/sanity-bridge'

const schema = sanitySchemaToPortableTextSchema(sanityBlockArraySchema)
const body = markdownToPortableText(markdown, {schema})

Use custom matchers when Markdown syntax must become specific Sanity objects:

const body = markdownToPortableText(markdown, {
  schema,
  types: {
    table: ({context, value}) => ({
      _type: 'table',
      _key: context.keyGenerator(),
      rows: value.rows,
      headerRows: value.headerRows,
    }),
  },
})

Only emit custom types that exist in the target schema.

Frontmatter Mapping

Use a frontmatter parser such as gray-matter:

npm install gray-matter

Map common fields deliberately:

  • title -> document title.

  • slug or file path -> slug.current.

  • date, published, updated -> explicit datetime fields such as publishedAt.

  • author -> reference, string, or author document depending on target schema.

  • tags and categories -> reference documents when they power filtering/navigation.

  • description, canonical, ogImage -> SEO object if the target schema has one.

  • Source file path -> migration metadata for debugging.

Do not put frontmatter into the Portable Text body unless it is actual editorial content.

Asset Handling

Markdown images need explicit handling:

  • Remote image: use _sanityAsset: "image@https://..." in NDJSON or upload through the client.

  • Local image: use an absolute file:///... URI in NDJSON, package assets into a tarball, or upload through the client.

  • Prefer the largest original image, not resized derivatives.

  • Preserve alt text from ![alt](src) and title text when present.

  • Rewrite image paths before conversion if Markdown uses relative paths.

  • Log unresolved images; do not silently keep broken local paths.

If images should remain inline inside Portable Text, ensure the Portable Text schema allows an image object. If images belong in a separate field such as mainImage, extract them before conversion.

Document IDs and Import

Use stable IDs:

  • File path slug: post-my-folder-my-file.

  • Frontmatter ID: post-<sourceId>.

  • Hash only when no stable source ID/path exists.

For bulk imports, prefer NDJSON:

{"_id":"post-example","_type":"post","title":"Example","body":[{"_type":"block","_key":"a","style":"normal","children":[{"_type":"span","_key":"b","text":"Hello","marks":[]}],"markDefs":[]}]}

Then import with:

npx sanity datasets import import.ndjson <dataset> --replace

Use client createOrReplace for smaller imports or incremental syncs.

Keep Markdown Native

Only keep Markdown native when the project intentionally wants Markdown editing/rendering instead of Portable Text querying and structured blocks.

If keeping Markdown native, use a Markdown field/plugin and document the tradeoff: simpler migration and editing for Markdown-first teams, but weaker structured querying, references, annotations, and block-level content reuse.

Validation Checklist

  • Confirm every document has _id, _type, title/slug where required, and a Portable Text array.

  • Confirm no body field is a raw Markdown string unless the target intentionally stores native Markdown.

  • Confirm all Portable Text custom _type values exist in the schema.

  • Confirm all image references resolve to remote URLs, absolute local file URLs, or uploaded Sanity asset IDs.

  • Confirm frontmatter dates parse to valid ISO datetime strings.

  • Confirm tags/authors/categories resolve according to the target model.

  • Confirm rerunning the transform produces the same IDs.

  • Confirm MDX JSX is mapped to Sanity objects, stripped, or logged for manual cleanup.

Requirements and compatibility

Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta

“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.

Needs: Needs Node.js

Security

No issues found by our static scan· No issues found

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Attribution and licence

Published by
Sanity
Publisher
Sanity (Official)
Source
sanity-io/agent-toolkit · skills/sanity-migration · commit 3ed3a14
Licence
MIT License (redistribution allowed)
  • LICENSE (added by AutoGineer from LICENSE)
  • ATTRIBUTION.md (written by AutoGineer)
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Download ZIP

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