Visual Edit

Visual Edit

Use /visual-edit when the user wants to inspect or edit a real local app visually instead of generating standalone Alpine HTML. The source of truth is the running localhost app plus its route URLs. Design shows those routes as iframe-backed screens on the infinite canvas.

The editor is hosted at https://design.agent-native.com. Never start local Design; only the target app and bridge run locally.

Fast local startup

• Do not install this skill into the target app or start a local Design server. The skill belongs to the coding host; Design is always the hosted app above.
• If you need to start an Agent-Native framework app yourself, use AUTH_DISABLED=1 with its normal dev command. This is local-only and gives the visual editor the framework's dev identity without a user login.
• If an agent-owned local server redirects a requested screen to /sign-in, restart that server with AUTH_DISABLED=1 and probe the route again before opening Design. Never present a sign-in page as the requested screen.
• Before calling open-visual-edit, verify the target URL responds. Start an agent-owned dev server with its normal command when it is down, and wait for the requested routes to respond before opening Design. Never leave a dead localhost URL in the canvas.
• Preserve a server you did not start; use its existing authenticated browser session or explain that the target app, rather than Design, requires login.
• When the user gives explicit paths, skip route inventory and place those paths directly. Discover routes only when paths were not supplied.

Installation

npx @agent-native/core@latest skills add visual-edit installs the skill and hosted Design MCP connector. npx skills@latest add BuilderIO/agent-native --skill visual-edit installs instructions only; page-capable WebMCP hosts need no connector installation.

Put Design Beside The Chat

Prefer the interactive MCP App from open-visual-edit: it keeps Design beside chat and routes Apply design updates through the host's MCP Apps bridge. The host may ask the user to confirm the current conversation. Otherwise, openUrl is a credential-free, read-only fallback; never claim it is editable.

• Inline-browser hosts should open https://design.agent-native.com/visual-edit and call its open-visual-edit WebMCP tool. It works signed in or out; the one-time capability is not a Design account session. A page-capable browser controller is enough, so Claude-in-Chrome, Claude Code browser tools, the ChatGPT Chrome/browser extension, Puppeteer or Playwright MCP, CDP, and similar JavaScript-capable controllers do not need the hosted MCP connector.
• VS Code uses its Design webview/deep link. Without page WebMCP, use the hosted Design MCP connector and its normal OAuth/device authorization. Never replace either path with a local Design server.

Inside Design, use Show/Hide UI from the Cmd K menu or press Figma's Shift \ shortcut to toggle all editing chrome so only the canvas remains.

Browser WebMCP (Default Without Connector)

Without a connected Design MCP, use a visible browser tab with a main-world JavaScript evaluator. Prefer the host's inline browser; use external Chrome only when requested or unavailable. Open https://design.agent-native.com/visual-edit, keep it visible while tools register, and read the title before work. Never enter, copy, or request passwords, cookies, tokens, or codes. Signed-out loopback visual-edit works; other pages that block tools behind sign-in still require a signed-in tab. If the browser exposes CDP permissions, grant local-network-access to https://design.agent-native.com before calling page tools; otherwise use the page's Connect button and let the browser's permission prompt complete.

Use a native browser-session WebMCP bridge when the host provides one: list once with list-browser-session-webmcp-tools and run with run-browser-session-webmcp-tool, or use the list-host-webmcp-tools and run-host-webmcp-tool pair. Preserve the exact discovered name, origin, and args. Otherwise use the page-world API. Agent-Native pages expose this helper:

Example assumes signed-in or existing bridge; fresh signed-out loopback must add the locally held bridgeToken described below.

const an = window.__agentNativeWebMcp;
const status = await an.ready({ waitMs: 20_000 });
if (status.state !== "ready") throw new Error(status.error ?? status.state);
const tools = await an.tools("visual-edit");
if (!tools.some((tool) => tool.name === "open-visual-edit")) {
  throw new Error("open-visual-edit is not registered yet");
}
const result = await an.call("open-visual-edit", {
  devServerUrl: "http://localhost:5173",
  paths: ["/"],
  navigate: true,
}, { waitMs: 2_000 });
if (result.state === "pending") {
  // On the next evaluation, read the still-running call without replaying it.
  an.result(result.id);
}

If the helper is absent, use standard WebMCP directly. document.modelContext is canonical; navigator.modelContext is deprecated:

const ctx = document.modelContext;
const tool = (await ctx.getTools()).find((candidate) => candidate.name === NAME);
if (!tool) throw new Error(`WebMCP tool not found: ${NAME}`);
const codex = typeof ctx.codexExecuteTool === "function" ||
  typeof ctx.codexGetTools === "function";
const result = await ctx.executeTool(tool, codex ? ARGS : JSON.stringify(ARGS));

The helper handles live discovery, partial registries, and pending calls. If a call returns state: "pending", read an.result(id) on the next evaluation; never replay a write. For Claude Code or Cowork, javascript_tool runs this page-world code with top-level await; for Codex open the page with cua.createBrowserTab("iab", url, { visible: true }), then use CDP Runtime.evaluate with awaitPromise: true; Puppeteer and Playwright MCP can use their page evaluator. Playwright isolated worlds cannot see document.modelContext. Keep evaluator output small, batch dependent calls, and do not navigate inside a batch.

Tool descriptors are page-local. Do not copy them into the host, hand-build authenticated HTTP requests, or replace named tools with clicks, typing, DOM automation, or screenshots. UI automation remains appropriate for canvas work without a named tool or when requested. If both bridges are unavailable after one discovery and one independent evaluator check, use hosted MCP/CLI before changing state.

For a fresh signed-out loopback connection, generate the bridge token locally, start the durable bridge with it, and pass that same token once as the page tool's bridgeToken; the page never returns it. Reuse a matching running bridge without the token. Account-backed or private Design work requires a signed-in session or the authenticated Design MCP connector. After canvas edits, call an.call("get-visual-edit-prompt", {}, { waitMs: 2_000 }) and apply the returned handoff. The page tool may show an approval dialog; let the user approve it and never bypass that consent.

Core Model

• Each screen is a URL-backed iframe, not copied HTML.
• Each screen keeps URL metadata: connectionId, routeId, path, url, bridgeUrl, title, and viewport size.
• Localhost Edit mode renders the running app through the local bridge as a live iframe with the same editor bridge used by HTML designs. It is never a frozen static DOM snapshot. Editing is direct DOM manipulation against that live document; the parallel /snapshot fetch feeds the editable source model only and must never be rendered in the frame.
• The /visual-edit skill needs no Design account sign-in. open-visual-edit mints a five-minute, single-use capability for the exact /visual-edit/:designId local-editor route. The MCP host redeems it outside model-visible text, then opens the existing editor with localhost edit access. A public /visual-edit/:designId route enables browser-only DOM editing of localhost screens; pending changes stay in the browser until applied. This capability is not an account session: /_agent-native/session remains signed out, and account-backed save/share/generate actions remain denied.
• The editor page registers a page-local WebMCP tool named get-visual-edit-prompt. Call it after canvas edits to retrieve the latest bounded source instructions instead of copying stale chat text. It returns status: "empty" when there is nothing to apply. If a previous editor session ended with unapplied edits, it returns status: "session-ended" with the pending count; status: "unknown" means the session marker could not be read and must not be treated as an empty result.
• The open-visual-edit action is owned by Design. From another app, use the hosted MCP server at https://design.agent-native.com/mcp or the page's WebMCP helper, not pnpm action in the target app. The page path works signed out only for loopback apps in public mode, using a short-lived capability-scoped principal; hosted MCP uses its normal OAuth identity.
• Ordinary public links stay read-only, including on loopback. Public /visual-edit/:designId is the browser-only DOM editing surface for public localhost designs; it never upgrades /design/* links or grants server writes. Loopback identity is not an authentication boundary because a tunnel or proxy can make a remote request appear local. Persisted writes remain role-gated.
• The live editor is same-origin through the local bridge proxy. This boots CSR apps and root-relative assets, but it is still a localhost editing proxy: app-origin cookies, WebSockets/HMR, SSE, and non-GET app API calls may need a future dev-server/plugin integration for perfect parity with the app's own origin.
• The canvas is the editing view; Interact runs the normal URL with rails and a device bar. Interact preserves navigation, scrolling, links, and controls; the canvas pans/zooms and suppresses native frame interaction.
• While a localhost screen has pending live visual edits, do not switch back to Interact until the user either applies the edits to source or explicitly aborts/discards the preview.
• Alt-drag duplicates a localhost frame and its URL metadata. Change the copy's path/query for another state; preserve the order of named or numbered flows. Shorthand like localhost:1234/onboarding/1 means http://localhost:1234/onboarding/1.

Useful Canvas Sets

Use a focused batch of 3-7 frames by default: one ordered frame per requested route/query state, repeat routes at requested desktop/tablet/mobile viewports, and include URL-addressable empty, loading, error, modal-open, or selected-item states. Keep the Screens section readable so Layers remains useful while editing. Do not expand beyond 7 frames unless the user explicitly asks for an exhaustive audit or a complete route inventory.

Do not expand every discovered route or every viewport unless the user asks for an exhaustive audit. Preserve the user's labels and sequence so the canvas reads like the workflow they described.

Select And Reprompt

When a chat message begins with [Reprompt selection], the selected subtree is a hard write boundary. The only mutation path is propose-node-rewrite with the exact repromptId, target, and baseVersionHash captured in design-reprompt-pending:<designId>:<fileId>. Never use apply-visual-edit, apply-source-edit, write-source, write-local-file, edit-design, or any other content-writing action for that request. Clarifying questions are allowed, but a requested change must remain a proposal.

Produce one variant by default. Produce two or three only when the instruction asks for options. A retry includes priorProposalId; keep the same target and base version, incorporate the feedback, and call propose-node-rewrite again. The UI previews the returned subtree without persisting it.

Use resolve-node-rewrite for the accept/reject lifecycle. Accept applies the chosen variant as one version-checked inline/Yjs content transaction so one undo restores the prior structure; reject clears the proposal without changing content. For conversational resolution such as "apply the second one," call view-screen, read the active design.reprompt.proposal, and pass its proposalId plus the zero-based variantIndex to resolve-node-rewrite.

Review Quality

Treat the running app as truth, preserving its component language, tokens, route state, and content. Compare visual edits before/after at requested viewports and check meaningful URL, hover, focus, scroll, and modal states.

Account And Sharing Model

• The capability permits live iframe inspection, session-local edits, undo/redo, Apply design updates, and Copy prompt. These hand bounded source instructions to the coding agent; they do not persist account-owned Design data.
• Public /design/:id links stay read-only without a signed-in owner/editor session. Never use the local capability to upgrade that ordinary sharing surface.
• Prefer links returned by Design actions or /_agent-native/open deep links; never surface _session= tokens or hand-build capability URLs.
• Do not attempt account-backed write actions with the browser capability. The trusted local open-visual-edit CLI call may register its bridge, create or reuse its workspace-owned local design, and place screens without an account. Direct source-file action writes, generation, saving into an account, and sharing still require an authenticated action caller. If a signed-out visitor wants those durable account operations, send them through the framework sign-in return flow first.

Required Local Bridge

The live-edit bridge is unlocked by a shared secret (the "bridge token") that must match on two sides: the local bridge process, and the user's connection row in Design (which the browser reads to authorize /live-edit-bridge, /read-file, /write-file). Get them to match by letting the open-visual-edit action mint the token, then starting the bridge with it. This is the only ordering that works for the remote-MCP flow - the bridge cannot push its own token to the server without a CLI auth token, so the server mints instead and the bridge adopts. The connectionId (usually localhost_...) only identifies the row; never pass it as bridgeToken.

For a fresh signed-out browser flow, generate the token locally, keep it in the host process, and pass it once as the page tool's optional bridgeToken; the page never returns it:

BRIDGE_TOKEN="$(node -e 'process.stdout.write(require("node:crypto").randomBytes(32).toString("hex"))')"
AGENT_NATIVE_BRIDGE_TOKEN="$BRIDGE_TOKEN" npx @agent-native/core@latest design connect --url http://localhost:5173 --root . --daemon

Reuse an existing matching connection without bridgeToken; hosted MCP can mint the token when page WebMCP is unavailable.

From the target app repo, make sure its dev server is running, then:

1. Discover routes without starting a durable bridge (one-shot, exits):

npx @agent-native/core@latest design connect --url http://localhost:5173 --root . --json

This prints the manifest (routes + capabilities). Parse it to build routeManifest for the next step. (Skip this if the user already gave explicit paths/URLs to place.)

Inside the agent-native monorepo itself, use the workspace CLI instead of npx — npx installs the last published @agent-native/core, which will not contain local changes and costs a slow install on every call:

pnpm dev:cli design connect --url http://localhost:5173 --root templates/<app> --json

2. For the hosted MCP path, call open-visual-edit (see Action Flow below) with NO bridgeToken. The server mints one, stores it on the user's connection row, copies it into the placed screens' metadata, and returns it to you as bridgeToken. Capture it.

3. Start the persistent bridge adopting that token (single line; prefer the env var so the secret does not appear in ps):

AGENT_NATIVE_BRIDGE_TOKEN="<bridgeToken from step 2>" npx @agent-native/core@latest design connect --url http://localhost:5173 --root . --daemon

(Equivalently, pass --bridge-token <token>.) This starts a detached bridge on http://127.0.0.1:7331, adopts the server-minted token — so bridge and row agree and live-edit authorizes with no self-registration — and stays alive after the command exits.

For a manual health/manifest check on the running bridge:

curl http://127.0.0.1:7331/health

/health needs no token. The full manifest at /manifest.json is preview-token protected, so an unauthenticated curl of it returns {"ok":false,"error":"invalid or missing preview token"} — that response means the bridge is up, not that it is broken.

Only use --json for the step-1 route probe. Never use --json, --once, or --dry-run for the durable step-3 bridge: they print the manifest and exit, so Design falls back to a non-editable live iframe.

The bridge listens on a single fixed port (7331) and refuses to start for a second, different app. It is detached with no log file, so if --daemon reports a timeout, check for a stale process (lsof -ti:7331) before retrying.

If local Design uses PGlite, never invoke the in-process CLI against that server: both open the same directory and the second owner is rejected. For a signed-out local test, start Design with AUTH_DISABLED=1, open /visual-edit, and call the server-action open-visual-edit through window.__agentNativeWebMcp after it registers. This keeps one PGlite owner; get-visual-edit-prompt is only the post-edit handoff. With auth enabled, sign in to hosted Design MCP or use shared Postgres before using the CLI action.

Action Flow

When a browser is available, reuse the local bridge and call the Design page's open-visual-edit WebMCP tool. For a fresh signed-out connection, pass the locally held bridgeToken; it reads its preview manifest and challenge proof, then sends both for validation. Hosted Design never fetches 127.0.0.1. If the page has no WebMCP, use the connected Design MCP server or its normal hosted MCP fallback.

From another app, call the connected Design MCP tool mcp__agent-native-design__open-visual-edit with the JSON arguments below. It registers or refreshes the localhost bridge, mints and stores the bridge token, creates or reuses a Design project, places URL-backed screens, stores visual-edit context, and navigates to overview mode in one call. Never run pnpm action from the target app's checkout: its local registry does not contain Design actions.

Call it before starting the durable bridge: it does not contact the bridge, so the server can mint bridgeToken for the bridge to adopt. Omit that input.

{
  "title": "Docs homepage visual edit",
  "devServerUrl": "http://localhost:5173",
  "bridgeUrl": "http://127.0.0.1:7331",
  "rootPath": "/absolute/path/to/app",
  "routeManifest": { "...": "from /manifest.json" },
  "paths": ["/", "/pricing", "/checkout?step=payment"]
}

The action returns designId, connectionId, bridgeToken, screens, urlPath, and credential-free openUrl. MCP App metadata carries the hidden one-time launcher. Keep the ids for follow-ups and pass the token to design connect; reusing the connection reuses its token.

Desktop and mobile side by side

Pass viewports to place every requested route once per viewport. Frames lay out as a grid: one row per route, one column per viewport. Presets are desktop (1280x900), laptop (1440x900), tablet (834x1112), and mobile (390x844); an explicit { "label": "...", "width": N, "height": N } also works.

{
  "title": "Tasks responsive visual edit",
  "devServerUrl": "http://localhost:5173",
  "bridgeUrl": "http://127.0.0.1:7331",
  "rootPath": "/absolute/path/to/app",
  "paths": ["/tasks", "/inbox"],
  "viewports": ["desktop", "mobile"]
}

Prefer this over two separate calls with defaultWidth/defaultHeight: it keeps each route's viewports aligned in a row and titles them Tasks — Desktop / Tasks — Mobile so the canvas reads clearly. viewports overrides defaultWidth/defaultHeight. With no routes/paths, it expands every route in the localhost manifest, which is usually far more frames than the user wants — name the paths.

Managing screens and breakpoints manually

Select a screen and use the right-rail Screen section to switch between Static HTML and URL-backed modes, edit its route/path, choose a localhost connection, add another URL screen, or remove the selected screen. URL mode keeps the iframe live; switching to Static stores a sanitized snapshot of the current frame, including its current client state when the page can provide it. The same operations are available to a page-capable agent through add-localhost-screens, update-screen-source, add-breakpoint, and remove-breakpoint.

Adding more page frames later

Call open-visual-edit again with the same designId and connectionId and only the new paths. Existing frames for the same route and viewport are refreshed in place rather than duplicated, and a frame the user has dragged or resized keeps its position unless you explicitly pass x/y/width/height.

{
  "designId": "<existing-design-id>",
  "connectionId": "<existing-connection-id>",
  "devServerUrl": "http://localhost:5173",
  "paths": ["/settings", "/team"],
  "startY": 2200
}

Do NOT add defaultWidth/defaultHeight just to restate the default size: supplying either one marks the viewport as explicitly requested, which overwrites frame sizes the user has already adjusted on the canvas.

For a numbered flow the user describes in chat, keep the labels and order:

{
  "designId": "<existing-design-id>",
  "connectionId": "<existing-connection-id>",
  "devServerUrl": "http://localhost:1234",
  "routes": [
    { "url": "localhost:1234/onboarding/1", "title": "Screen 1" },
    { "url": "localhost:1234/onboarding/2", "title": "Screen 2" },
    { "url": "localhost:1234/onboarding/3", "title": "Screen 3" }
  ]
}

If no routes or paths are supplied, open-visual-edit uses every route from the localhost manifest.

Fallback only when open-visual-edit is unavailable and hosted Design MCP is authorized:

1. Register or refresh the bridge with connect-localhost, passing the /manifest.json result as routeManifest and capabilities.
2. Create or reuse a Design project with create-design.
3. Place URL-backed screens with add-localhost-screens.
4. Navigate to overview mode with navigate.

The fallback still targets https://design.agent-native.com; only the app and bridge URLs are localhost. Never run pnpm action from templates/design.

Open The Design Surface

• Use the link, deepLink, or MCP App embed returned by Design actions so the user sees the canvas. Prefer the MCP App; its host launcher carries the one-time capability. The credential-free openUrl is read-only fallback.
• Never return or open a hand-built /design/:id?_session=... URL.
• If the user is working in VS Code, the Agent-Native extension can open the same URL via vscode://builder.agent-native/open?url=<encoded-design-url>. Its Agent-Native: Open Design Canvas command also starts the local bridge and opens hosted Design in the VS Code side panel.
• Once open-visual-edit returns the expected screenCount, hand back the link and stop. Do not open it yourself in a browser-automation tool to screenshot or poll until it renders — a cold dev server can take 10-30s regardless of who's watching, and that wait adds nothing the response didn't already confirm. Reach for browser automation only if the user later reports the canvas is broken.

Applying Visual Edits Back To Source

With the Design tab closed, recover the bridge handoff with:

npx @agent-native/core@latest design pending --root .

It prints the source prompt; empty JSON means this bridge has no pending edits.

Canvas edits on a localhost screen do not write source as you make them. They accumulate as pending edits and the editor shows an Apply design updates button on the canvas. An MCP App sends the bounded prompt to the host; otherwise it uses the local Design agent. The dropdown's Copy prompt to your agent action is the manual fallback.

ChatGPT, Claude, and WebMCP hosts receive a short instruction to call get-visual-edit-prompt; Apply sends the same batch when the host bridge is available, while ordinary browsers copy the detailed handoff.

• Style, text, and drag/drop structure edits all collect into the same pending batch, so the user can make several changes and apply once.
• After the write lands, the target app's own dev-server HMR refreshes the frames — no manual reload. If frames do not refresh, the write did not land; say so rather than assuming.
• The separate disk-icon "Apply to source" button is the deterministic whole-file HTML/CSS writer. It is intentionally disabled for compiled .jsx/.tsx routes — those must go through the agent path above.

Editing URLs

Keep localhost screens as URL files plus screenMetadata[fileId]. Do not replace them with copied srcdoc HTML unless the user explicitly asks for a frozen snapshot. To change a state, rerun open-visual-edit with the new path/query, use the Screen settings section, call update-screen-source, or duplicate the screen and update the copy's URL metadata.

Local Files in the Code Tab

Once a connection is registered, the design editor's Code panel (left rail → Code, or navigate --view editor --designId <id> --leftPanel code) shows a local-files workspace root for that connection next to the design's own files. Treat that root like VS Code opened at the connected project directory: file tree, search, open/edit, and save are backed by the real local files. It lists the connected app's text/code files through the bridge (list-local-files / read-local-file); build output, node_modules, .git, and secret-looking paths (.env*, key files) are always excluded.

• Browsing and reading need only editor access on the design plus the running bridge.
• Saving goes through write-local-file: the first save opens the write-consent dialog (an 8-hour, folder-scoped grant) and retries automatically once granted. Only text/code files are writable; secret paths are always blocked.
• If the agent calls write-local-file directly (not through a UI save) and it fails with "no write-consent grant", call request-localhost-write-consent. It opens the write-consent dialog in the editor, or reports alreadyGranted if one already exists. Granting is human-only — grant-localhost-write-consent is hidden from agents, so you cannot approve it yourself. Tell the user to click "Allow writes", then retry write-local-file once. Do not keep retrying blindly: the write stays blocked until the user approves.
• Saves are conflict-checked against the file's on-disk version — a file that changed since it was read fails with a version conflict instead of being overwritten.

React Source Writeback

• Use compiler/debug provenance (project-relative file, line, column, component, and runtime multiplicity) to locate React/TSX source. Treat it as evidence, not as permission for a generic AST structural transform.
• Read positionPrecision on every anchor before you trust line/column. authored means those are the real JSX coordinates. transformed means they are the dev server's own output coordinates — React 19 removed _debugSource and exposes only an owner stack, so this is the normal case on a Vite/Next dev server, and the line will not match the file. unknown means no tier was reported. On anything but authored, use the file and component to find the element by its JSX shape and re-derive the line from the file you read; never edit at the reported line.
• A single-instance leaf text edit, literal className/class edit, or flat literal style={{ ... }} property may use apply-visual-edit with a local-file source and a complete target.sourceAnchor. Forward the anchor's positionPrecision with it — the action refuses a transformed anchor with status: "needsAgent" instead of seeking to a line that means something else in the authored file. Preview first (omit persist), inspect proposedDiff, then call with persist: true.
• Reparenting, grouping/ungrouping, wrappers, dynamic expressions, repeated .map() instances, shared components, breakpoint-scoped edits, and cross-file changes go through the coding agent with complete subject/target anchors and their runtime relationship. apply-visual-edit refuses these with status: "needsAgent" rather than guessing.
• Before each write, read the file and pass its exact versionHash to write-local-file with requireExpectedVersionHash: true; on conflict, re-read and re-plan. Keep the optimistic preview until HMR/runtime confirms the result. Human write consent remains mandatory and agents cannot grant it.

Verification

For a plain "open this app" request, open-visual-edit's own response is the verification — see Open The Design Surface. Reach for the checks below only to diagnose an actual report, or to confirm an applied edit landed:

• list-localhost-connections returns the expected connection and routes.
• The Design editor opens in overview mode.
• Every requested screen renders the intended localhost URL, showing real app content rather than an endless loading spinner.
• The screen iframe carries a src, not a srcdoc. A localhost screen with a srcdoc is a bug, not a slow load — check it in the browser devtools before reporting the canvas as working.
• Alt-dragging a screen copies the URL-backed frame, not an inline HTML clone.
• A query/path edit changes only the target screen's URL metadata and iframe.
• get-visual-edit-prompt returns the latest pending source handoff from the page without requiring a Design account.
• The Code tab shows a local-files root for the connection and opens its files.