Markstream Migration

Use this skill when a repo already renders Markdown and the task is either to adopt Markstream safely or to upgrade an existing markstream-vue 1.x integration to 2.x.

Choose The Migration Route

Inspect package.json, the lockfile, imports, and renderer props before changing code.

• If the repo already depends on markstream-vue 1.x, read references/vue-1x-to-2x.md and follow Route B. Confirm the package dependency instead of routing only from shared names such as MarkdownCodeBlockNode or InternalParseOptions, which can also appear in other adapters.
• Otherwise, when replacing react-markdown, markdown-it, marked, or another renderer with a Markstream package, read references/adoption-checklist.md and follow Route A.
• If both apply, complete the 1.x to 2.x package and API upgrade first, then audit the separate renderer replacement as an adoption task.

Route A: Adopt Markstream From Another Renderer

1. Audit the repo's current renderer usage.

• Search for markdown renderers, plugin chains, raw HTML handling, security props, and custom renderers.
• List every call site that will be touched.

1. Classify the migration.

• direct: simple string-in renderer swap.
• renderer-custom: custom renderers but limited parser work.
• plugin-heavy: remark, rehype, markdown-it, or other transform-heavy pipelines.
• security-heavy: allow or deny lists, URL rewriting, sanitization, or raw HTML policies.

1. Swap the renderer first.

• Introduce the correct Markstream package and CSS.
• Import Markstream CSS through the package CSS subpath; do not rely on the renderer import to inject styles.
• Preserve user-visible behavior before adding richer Markstream-only features.
• Audit whether the old renderer allowed broad raw HTML or Mermaid loose-mode HTML labels before claiming parity.

1. Migrate custom renderers.

• Convert built-in node renderers into scoped node-type overrides.
• In React, prefer renderer-local streamingComponents for parser-backed tags and htmlComponents for sanitized HTML-prop components; use setCustomComponents for built-in node overrides or shared compatibility registration.
• In Svelte or Angular, prefer the renderer-local customComponents input when the mapping does not need shared registration.
• For trusted tag-like content, prefer customHtmlTags.
• Use parseOptions.preTransformTokens, postTransformTokens, or postTransformNodes only when the old pipeline truly requires token or AST transforms.

1. Review gaps honestly.

• Do not claim 1:1 parity where none exists.
• Call out parser, plugin, security, or HTML behavior that still needs manual review.

1. Consider renderer mode and smooth streaming before jumping to nodes.

• For Vue 3, choose mode="chat" for AI/SSE output, mode="docs" for rich document surfaces, and mode="minimal" for lightweight non-chat surfaces.
• If the app streams content and only needs pacing, smooth-streaming="auto" (the default) handles it without requiring nodes.
• Move to nodes only when the app needs custom AST control, worker preparsing, or high-frequency structural updates.
• In Vue 3 (including Nuxt), smooth-streaming controls output pacing and fade controls opacity; they can be enabled together. mode="chat" keeps fade=false as a lightweight default. Add fade when gradual text reveal is desired; keep it off when animation cost matters more. Do not carry a legacy :fade="!isStreaming" binding into a Vue 3 migration unless the host wants that policy.
• Streaming vs recovering history: when migrating a chat UI, keep mode="chat" on the same chat row and switch pacing/animation props instead. Vue 3 streaming: mode="chat", final, and optional fade. Vue 3 completed chat history: keep mode="chat", use :smooth-streaming="false" when pacing is unnecessary, and choose fade independently. Use mode="docs" only for separate rich document surfaces.

1. Validate and summarize.

• Run the smallest relevant tests or build.
• Report direct mappings, TODOs, and remaining verification work.

Route B: Upgrade markstream-vue 1.x To 2.x

1. Freeze the current integration surface.

• Record the installed markstream-vue version and package-manager resolution.
• Find old code-block dependencies, renderer values, props, public types, runtime helpers, preview handlers, and direct parser imports.
• Identify the smallest build, typecheck, SSR, and code-block checks that prove the current behavior.

1. Choose one release line.

• Use the coordinated beta family only after it is published and next resolves to that generation, or markstream-vue@2 after stable release.
• Check registry versions and dist-tags before editing the manifest; repository version bumps do not prove that a package is installable.
• Install only the adapter used by the application. Add parser or core directly only when the application imports it directly.
• Keep packages on the same prerelease generation; do not mix unrelated beta versions.

1. Apply only the required dependency and API changes from references/vue-1x-to-2x.md.

• Remove both former code-block runtimes. Rename supported monacoOptions / codeBlockMonacoOptions fields to the shared codeBlockOptions contract and delete unsupported Monaco-only fields.
• Add stream-diffs only when enhanced code or diff blocks are required; otherwise use the plain fallback.
• Preserve the existing Markdown, diagram, math, HTML-policy, worker, CSS, streaming, and virtualization setup unless a documented 2.x break requires a change.

1. Validate the migrated behavior and leave a rollback path.

• Check package resolution, public types, preview payload consumers, normal and diff fences, themes, responsive diff layout, and SSR or packed installs where relevant.
• Report the exact 1.x version or legacy dist-tag that restores the previous line.

Default Decisions

• Renderer swap first, streaming optimization second.
• Do not treat an existing Markstream version upgrade as a renderer-adoption rewrite.
• For 1.x to 2.x, preserve application behavior outside the documented code-block and parser changes.
• Keep a coordinated beta family on one prerelease generation and make rollback explicit before changing dependencies.
• Smooth streaming is an intermediate option between "just content" and "full nodes migration": it paces visible output without requiring AST control.
• Preserve safety over feature parity when HTML or security rules are involved.
• Prefer explicit TODOs over vague claims.
• Prefer renderer-local component maps where the target framework exposes them.
• Recommend against migration when the current stack depends heavily on transforms that Markstream does not mirror directly.
• When preserving trusted legacy behavior is necessary, use scoped htmlPolicy / html-policy="trusted" and mermaidProps.isStrict = false instead of weakening defaults everywhere.

Useful Doc Targets

• docs/guide/migration-2-0.md
• docs/guide/react-markdown-migration.md
• docs/guide/react-markdown-migration-cookbook.md
• docs/guide/ai-chat-streaming.md
• docs/guide/installation.md
• docs/guide/component-overrides.md
• docs/guide/advanced.md