Add `display-review` tool for agentic review by yannbf · Pull Request #230 · storybookjs/mcp

yannbf · 2026-05-19T15:58:58Z

The agent pushes a curated review (narrative, labeled clusters with
optional semantic kind, changed files, diff hunks, optional per-story
depth/chain) via this MCP tool. It validates with valibot, caches the
state in memory, broadcasts it over the Storybook channel, and returns
the review-page URL.

Gated behind FEATURES.changeDetection.

Pairs with the @storybook/addon-review Storybook package.

netlify · 2026-05-19T15:59:05Z

✅ Deploy Preview for storybook-mcp-self-host-example canceled.

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changeset-bot · 2026-05-19T15:59:06Z

🦋 Changeset detected

Latest commit: 7d424c1

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@storybook/addon-mcp	Minor

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

pkg-pr-new · 2026-05-19T15:59:37Z

npx https://pkg.pr.new/storybookjs/mcp/@storybook/addon-mcp@230

npx https://pkg.pr.new/storybookjs/mcp/@storybook/mcp@230

npx https://pkg.pr.new/storybookjs/mcp/@storybook/mcp-proxy@230

commit: 7d424c1

codecov · 2026-05-19T16:00:22Z

Bundle Report

Changes will decrease total bundle size by 3.58kB (-4.33%) ⬇️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
@storybook/addon-mcp-esm*	1.48kB	-3.58kB (-70.78%) ⬇️

ℹ️ *Bundle size includes cached data from a previous commit

Affected Assets, Files, and Routes:

view changes for bundle: @storybook/addon-mcp-esm

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
`preview.js` (New)	1.48kB	1.48kB	100.0% 🚀
~~*`preview-.js`*~~ (Deleted)*	-5.05kB	0 bytes	-100.0% 🗑️

Files in preview.js:

./src/constants.ts → Total Size: 138 bytes

codecov · 2026-05-19T16:00:25Z

Codecov Report

❌ Patch coverage is 87.03704% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.25%. Comparing base (9c26064) to head (7d424c1).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
packages/addon-mcp/src/tools/display-review.ts	86.66%	1 Missing and 3 partials ⚠️
packages/addon-mcp/src/mcp-handler.ts	50.00%	1 Missing and 1 partial ⚠️
...-mcp/src/instructions/build-server-instructions.ts	75.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #230      +/-   ##
==========================================
+ Coverage   77.77%   78.25%   +0.48%     
==========================================
  Files          55       57       +2     
  Lines        1498     1550      +52     
  Branches      415      430      +15     
==========================================
+ Hits         1165     1213      +48     
  Misses        202      202              
- Partials      131      135       +4

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

Copilot

Pull request overview

Adds an agent-facing MCP tool (apply-review-state) to push a structured “curated review” payload into a running Storybook instance, cache it in-memory, and broadcast it to Storybook tabs so the paired @storybook/addon-review-changes manager page can render it. The tool is only registered when features.changeDetection is enabled, aligning it with the existing “changed stories” workflow.

Changes:

Introduces apply-review-state MCP tool with Valibot validation + structured output containing a reviewUrl.
Adds an in-memory review state store + Storybook channel event constants and a replay mechanism on tab refresh.
Registers the tool under the existing features.changeDetection gate and adds a Changesets entry.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
packages/addon-mcp/src/tools/tool-names.ts	Adds the `apply-review-state` tool name constant.
packages/addon-mcp/src/tools/apply-review-state.ts	Implements the new MCP tool (validation, caching, channel broadcast, URL return).
packages/addon-mcp/src/review-state-store.ts	Defines the canonical Valibot schema + module-scope cache for the review payload.
packages/addon-mcp/src/preset.ts	Replays cached review state to newly mounted/refreshed tabs via Storybook channel events.
packages/addon-mcp/src/mcp-handler.ts	Registers the tool when `features.changeDetection` is enabled.
packages/addon-mcp/src/constants.ts	Adds cross-addon channel event names + the manager route constant for the review page.
packages/addon-mcp/LOCAL_STORYBOOK_DEV.md	Adds local dev instructions for cross-repo iteration (currently marked “do not merge”).
.changeset/apply-review-state.md	Declares a minor release for `@storybook/addon-mcp` adding the tool.

Copilot

Pull request overview

Copilot reviewed 15 out of 18 changed files in this pull request and generated no new comments.

Files not reviewed (3)

apps/internal-storybook/pnpm-lock.yaml: Language not supported
eval/pnpm-lock.yaml: Language not supported
packages/addon-mcp/pnpm-lock.yaml: Language not supported

Copilot

Pull request overview

Copilot reviewed 15 out of 18 changed files in this pull request and generated 2 comments.

Files not reviewed (3)

apps/internal-storybook/pnpm-lock.yaml: Language not supported
eval/pnpm-lock.yaml: Language not supported
packages/addon-mcp/pnpm-lock.yaml: Language not supported

The agent pushes a curated review (narrative, labelled clusters with optional semantic kind, changed files, diff hunks, optional per-story depth/chain) via this MCP tool. It validates with valibot, caches the state in memory, broadcasts it over the Storybook channel, and returns the review-page URL. Gated behind FEATURES.changeDetection. Pairs with the @storybook/addon-review-changes Storybook addon.

Copilot

Pull request overview

Copilot reviewed 16 out of 19 changed files in this pull request and generated no new comments.

Files not reviewed (3)

apps/internal-storybook/pnpm-lock.yaml: Language not supported
eval/pnpm-lock.yaml: Language not supported
packages/addon-mcp/pnpm-lock.yaml: Language not supported

Copilot

Pull request overview

Copilot reviewed 15 out of 15 changed files in this pull request and generated 4 comments.

Copilot

Pull request overview

Copilot reviewed 15 out of 15 changed files in this pull request and generated 3 comments.

Copilot

Pull request overview

Copilot reviewed 15 out of 15 changed files in this pull request and generated 2 comments.

+/** Default MCP endpoint path. Kept in sync with `DEFAULT_MCP_ENDPOINT` in preset.ts. */
+const DEFAULT_ENDPOINT = '/mcp';
+


Copilot

Pull request overview

Copilot reviewed 15 out of 15 changed files in this pull request and generated 1 comment.

+				// Hand the payload off to @storybook/addon-review
+				server.ctx.custom?.options?.channel?.emit(PUSH_REVIEW_EVENT, input);


ghengeveld · 2026-05-27T17:44:02Z

+	let hasAddon = false;
+	try {
+		const mainConfig = await loadMainConfig({ configDir: options.configDir });
+		hasAddon = getAddonNames(mainConfig).includes(REVIEW_ADDON_NAME);


Should we use feature detection rather than the presence of an addon? This will break if we decide to merge the addon into core.

Sounds good, I’ll make the change!

ghengeveld · 2026-05-27T17:47:34Z

+	features?: { changeDetection?: boolean } | undefined;
+}
+
+export const getReviewStatus = async (


Name is inconsistent with filename.

I made it consistent with the “is-manifest-available” and getManifestStatus. If I change it I’d have to change both otherwise it’s not consistent across the codebase

ghengeveld · 2026-05-27T18:01:00Z

+
+Anti-pattern: editing a theme token that only one component reads, then publishing a review with just that one component's story. The token change is visible on every page that renders the component — include those pages.
+
+Always include the returned reviewUrl in your final user-facing response so the user can open it.`,


Would be good to add this clarification, so the agent has a notion of what happens when it submits multiple times:

This tool maintains a single active review state; each call replaces the previously published review.

yannbf self-assigned this May 19, 2026

Copilot AI review requested due to automatic review settings May 19, 2026 15:58

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Comment thread packages/addon-mcp/src/preset.ts Outdated

Comment thread packages/addon-mcp/src/tools/apply-review-state.ts Outdated

Comment thread packages/addon-mcp/src/mcp-handler.ts

Comment thread packages/addon-mcp/LOCAL_STORYBOOK_DEV.md Outdated

ghengeveld reviewed May 19, 2026

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Comment thread packages/addon-mcp/LOCAL_STORYBOOK_DEV.md Outdated

yannbf commented May 21, 2026

View reviewed changes

Comment thread packages/addon-mcp/src/tools/display-review.ts

yannbf commented May 21, 2026

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Comment thread packages/addon-mcp/src/tools/apply-review-state.ts Outdated

yannbf force-pushed the yann/agentic-review-mcp-integration branch from 86ad2bc to 638a168 Compare May 21, 2026 14:07

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yannbf force-pushed the yann/agentic-review-mcp-integration branch 2 times, most recently from 23849ba to a42bba0 Compare May 21, 2026 15:36

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Comment thread .changeset/apply-review-state.md Outdated

Comment thread packages/addon-mcp/src/tools/apply-review-state.ts Outdated

Copilot AI review requested due to automatic review settings May 22, 2026 13:50

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yannbf force-pushed the yann/agentic-review-mcp-integration branch from 96b12bf to 9327b89 Compare May 22, 2026 13:52

yannbf added 3 commits May 22, 2026 15:54

update schema

f9727f0

add retries to story index fetch

4e3acfe

Copilot AI reviewed May 22, 2026

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yannbf added 2 commits May 22, 2026 15:55

fix tests and review comments

a2c1c20

add branch name

755eb12

Copilot AI reviewed May 27, 2026

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Comment thread packages/addon-mcp/src/mcp-handler.ts

Comment thread packages/addon-mcp/src/mcp-handler.ts Outdated

Comment thread packages/addon-mcp/src/constants.ts Outdated

Comment thread packages/addon-mcp/src/instructions/dev-instructions.md

JReinhold approved these changes May 27, 2026

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yannbf added 2 commits May 27, 2026 14:59

improve getReviewStatus

fe11c73

PR review fixes

f3bee6f

Copilot AI review requested due to automatic review settings May 27, 2026 13:15

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yannbf added 2 commits May 27, 2026 15:16

Merge branch 'main' into yann/agentic-review-mcp-integration

f2116fc

fixes

5fe1a6d

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Comment thread packages/addon-mcp/src/tools/display-review.ts

Comment thread packages/addon-mcp/src/tools/display-review.ts Outdated

Comment thread packages/addon-mcp/src/tools/display-review.ts

yannbf added 2 commits May 27, 2026 15:49

improve prompt and data

f453508

improve url handling

ca09074

Copilot AI review requested due to automatic review settings May 27, 2026 14:00

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Comment thread packages/addon-mcp/src/mcp-handler.ts Outdated

Comment on lines +29 to +31

/** Default MCP endpoint path. Kept in sync with `DEFAULT_MCP_ENDPOINT` in preset.ts. */

const DEFAULT_ENDPOINT = '/mcp';

Comment thread packages/addon-mcp/src/tools/display-review.ts

yannbf added 2 commits May 27, 2026 16:11

update prompt

e406bc8

extract default MCP endpoint to a constant

238729f

Copilot AI review requested due to automatic review settings May 27, 2026 14:24

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Comment thread packages/addon-mcp/src/tools/display-review.ts

Comment on lines +138 to +139

// Hand the payload off to @storybook/addon-review

server.ctx.custom?.options?.channel?.emit(PUSH_REVIEW_EVENT, input);

ghengeveld approved these changes May 27, 2026

View reviewed changes

improve server instructions

7d424c1

yannbf merged commit b38e71c into main May 28, 2026
16 checks passed

yannbf deleted the yann/agentic-review-mcp-integration branch May 28, 2026 08:09

This was referenced May 28, 2026

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storybook-app-bot Bot mentioned this pull request Jun 5, 2026

Version Packages #275

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		/** Default MCP endpoint path. Kept in sync with `DEFAULT_MCP_ENDPOINT` in preset.ts. */
		const DEFAULT_ENDPOINT = '/mcp';

		// Hand the payload off to @storybook/addon-review
		server.ctx.custom?.options?.channel?.emit(PUSH_REVIEW_EVENT, input);


		Anti-pattern: editing a theme token that only one component reads, then publishing a review with just that one component's story. The token change is visible on every page that renders the component — include those pages.

		Always include the returned reviewUrl in your final user-facing response so the user can open it.`,

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