deer-flow/docs/full-stack-plugins.md

Full-stack plugin contributions

A deployment-installed Python extension can register a PluginContribution with optional browser code, authenticated backend actions and model tools. This extends the existing install(registry, config) workflow. MCP and Skills keep their existing APIs and lifecycles. Public contracts live in deerflow_extension_api (0.2.3).

The browser contribution API is experimental. BrowserModule(code=...) remains the self-contained transport; BrowserAssets(root=...) adds manifest-listed resources without changing the page/action API or requiring a host frontend rebuild.

What users see

Capability Center has an Extensions tab with read-only information and deployment status. A plugin can add a conversation action, its own workspace page and an optional sidebar entry. The bookmarks example uses all three: save the last visible answer, then search, rename or delete it under My bookmarks. Existing notification and Markdown/JSON export behavior is unchanged.

Registration and execution

registry.plugin(...) returns True when accepted. Its default public protocol implementation returns False on a host without support, so packages must check the result. A declaration needs a unique namespace and at least one browser module, backend action or tool. Validation happens before registration; install failures use the existing positional rollback and source attribution.

• BrowserModule(module, code, public_fields=()) contains a self-contained ES module, at most 512 KiB. It may export surfaces and conversationActions with apiVersion: 1.
• BrowserAssets(module, root, manifest="ui_manifest.json", public_fields=()) loads a versioned resource manifest from an installed package (details below).
• BackendAction(name, handler) declares an async handler receiving a JSON object and ActionContext(principal, settings). The principal comes from host authentication.
• ModelTool(name, description, input_schema, handler, group="extensions") declares an async handler with a ToolContext that additionally carries the thread ID. Object schemas must be inline: reference resolution is rejected. Tools enter the ordinary host tool assembly, including group filtering and later authorization.
• SettingsField describes a non-secret deployment value. There is no online override store or settings write API. Browser clients see only enabled and explicitly listed public fields. Plugin code remains responsible for business authorization.

Tool names are namespace-derived and collision-checked. Tool inputs are bounded to 256 KiB, outputs to 64 KiB and execution to 30 seconds. Backend actions accept object inputs up to 256 KiB and have a 30-second timeout. Cancellation does not guarantee rollback of external effects or already-running worker-thread operations.

Durable batch_task workers pin the Gateway app's extension snapshot at startup and use it for both plugin tools and subagent execution. Recovered items use the new worker's snapshot after restart; no Python snapshot is stored in the durable execution_spec. Standalone batch services without an explicit snapshot capture the process default once at construction.

Browser API

The authenticated host exposes:

Route	Purpose
GET /api/plugins	Deployed descriptors, public configuration and declared actions
GET /api/plugins/modules/{module}/{sha256}.mjs	Installed code with a content revision
GET /api/plugins/{namespace}/assets/{revision}/{path}	One manifest-listed static resource
POST /api/plugins/{namespace}/actions/{name}	Invoke one declared backend action

The host does not accept filesystem paths, import strings or arbitrary remote URLs from the browser. Inline modules use JavaScript content type and private no-store caching; packaged assets use their declared file type and private immutable caching. Both transports send nosniff. Existing Gateway session/CSRF policies apply; PATs do not gain a new route allowlist. The browser sends its descriptor's viewer ID so the action route can reject a stale view after account changes, in addition to normal request authentication.

Inline module downloads honor NEXT_PUBLIC_BACKEND_BASE_URL, including a path prefix, and use the host's authenticated fetch helper before importing a temporary Blob URL. The URL is released after import, including on failure. Browser modules must be self-contained: relative imports and assets resolved against import.meta.url are unsupported. Deployments with a Content Security Policy must allow blob: in script-src and the configured backend in connect-src; split-origin backends must allow credentialed CORS from the frontend, as for other host API calls.

A page surface declares id, slot: "page", title, mount(root, context) and optional navigation: { label, labelZh?, icon? }. The host generates the URL /workspace/extensions/{namespace}/{id} and mounts only that registered page. mount returns a synchronous dispose() callback. The context includes locale, public settings, an abort signal and a namespace-bound callBackend helper. The optional openConversation(threadId) host helper reads current conversation metadata through the authenticated API and uses the host's normal/custom-agent routing rules. Missing or inaccessible conversations reject without navigating; unmount/account changes abort pending reads and prevent late navigation. Cleanup aborts outstanding work and fences late callbacks. Plugin async work should observe the signal and release resources in dispose().

Conversation actions receive a conversation context and host services. The latestVisibleAnswer and conversationText services reuse the existing export sanitizer; sidebar reads go through the authenticated conversation API. Plugin code must still escape user/model text when rendering it. Factories and availability callbacks must be synchronous; invalid Promise returns are rejected and their rejections consumed. The host validates each locale-dependent action group and evaluates availability inside a per-plugin error boundary. A malformed or throwing contribution is omitted without removing healthy plugin actions or failing the conversation page. Plugin tool names that collide with ordinary tools follow the host's ordinary-first deduplication; unrelated tools remain available. Duplicate names within the plugin tool set still fail strict validation.

Packaged resources (assets-v1)

Register a package-owned directory alongside the Python implementation:

from pathlib import Path
from deerflow_extension_api import BrowserAssets, PluginContribution

registry.plugin(PluginContribution(
    namespace="community.example",
    title="Example",
    frontend=BrowserAssets("example.v1", Path(__file__).parent),
))

Place ui_manifest.json at that root, and include it and every listed file in the installed wheel. The bookmarks package is a working example. Its manifest uses this schema:

{
  "schema_version": 1,
  "entry": "static/dist/index.mjs",
  "files": [
    "static/dist/index.mjs",
    "static/dist/chunks/bookmarks.mjs",
    "static/dist/styles.css",
    "static/dist/bookmark.svg"
  ]
}

entry must be a listed .js or .mjs ES module exporting the existing browser API v1 object. Relative static/dynamic imports and new URL(..., import.meta.url) resolve within the revision's URL tree. Bundle third-party dependencies into the package: bare npm imports and shared host React instances are not provided. Emit relative URLs, not absolute /assets/... paths from a bundler's default public path.

The manifest accepts only schema_version, entry and files; unknown versions, extra/duplicate keys, duplicate paths, missing files and symlinks are rejected at registration. The declared root itself must not be a symlink (including a dangling link); ordinary parent directory aliases are resolved before checking package files. Paths use ASCII letters, digits, _, -, . and / separators; segments must start with a letter, digit, _ or -. Dotfiles, dot segments, empty segments, percent encoding, query strings and backslashes are rejected. No directory listing or unlisted file is served. Limits: 64 KiB manifest, 256 files, 4 MiB per file and 16 MiB total per plugin. These limits bound the in-memory startup snapshot.

Supported types are JS/MJS, CSS, JSON/source maps, WASM, PNG/JPEG/GIF/WebP/SVG/ICO and WOFF/WOFF2/TTF/OTF. HTML and executable server files are not served. SVG can contain active document content, so asset responses carry Content-Security-Policy: sandbox: direct navigation cannot execute scripts or retain the Gateway's origin. This document restriction preserves image, stylesheet and module subresource use; it does not sandbox the plugin JavaScript deliberately loaded into the host page. Do not list secrets or private build sources; any authenticated user can download listed assets, including source maps, even when the contribution is disabled.

The host snapshots all listed bytes during registration and computes a SHA-256 revision over the manifest, paths and file content hashes. Changing any resource changes every resource URL's revision. Requests read that immutable snapshot, not the filesystem. Responses require authentication and send Cache-Control: private, max-age=31536000, immutable, Vary: Cookie, Authorization and the file's MIME type. Missing files/revisions return 404 with private, no-store. There is no public CDN contract or retained historical snapshot. A browser can retain already cached code after removal; uncached old resources require a page reload after restart/upgrade. Installation and authorization are not instantaneous cache revocation.

Discovery labels the transport inline-v1 or assets-v1. The frontend rejects unknown transports and treats an omitted transport as legacy inline v1. Deploy the matching host frontend/backend together before installing an assets-v1 plugin; this does not make old host frontends support the new transport.

For packaged JavaScript the host inserts a native module script with crossorigin="use-credentials", then obtains exports from the document's module map. This preserves authenticated static and lazy imports without rewriting source or Blob URLs. See the HTML module-script credential rules. URLs honor NEXT_PUBLIC_BACKEND_BASE_URL, including relative/absolute prefixes. The host stops waiting after 30 seconds and rejects that contribution, removing its loading script node. This is a waiting deadline, not execution cancellation: native module fetching/evaluation can continue and top-level side effects can occur later. A late completion cannot change the already rejected host result. Blocking synchronous plugin code can also delay the deadline's timer. Trusted plugins should keep top-level code free of user-visible side effects, start UI work in mount and release it in dispose. This loader does not provide preemption, rollback or a security sandbox.

Module exports are shared within a document. Keep viewer data in per-mount state, observe the host abort signal and clear it on dispose; never retain principals or private results in module-level state across account changes. Split-origin deployments need exact-origin credentialed CORS and working session cookies; browser third-party cookie restrictions still apply.

Other resource requests are the plugin's responsibility: attach a stylesheet or image with crossOrigin = "use-credentials", and use fetch(url, { credentials: "include" }) for WASM, JSON or binary assets. CSS font/background requests do not universally carry cross-origin session cookies. Prefer same-origin deployment for such CSS references, or fetch with credentials and construct a FontFace/Blob URL, releasing it on dispose. The host does not rewrite CSS URLs or add authorization tokens to URLs. CSP must allow the backend origin in the applicable script-src, style-src, img-src, font-src and connect-src directives. Inline-v1 still needs blob: in script-src.

Trust and lifecycle

Browser and Python plugins are trusted operator-installed code. Browser modules run in the main page. Shadow DOM scopes CSS; it is not a security sandbox, and a plugin can access same-origin browser capabilities. No shared React instance is promised: plugins mount their own DOM rather than providing a component for the host React tree. Sandboxed iframes, right-side panels, composer selection and version negotiation beyond API v1 checks are follow-up designs discussed in #5510 and #5539.

Install, remove, enable/disable or upgrade with the existing deployment/CLI workflow and restart the service. Python packages must be delivered into the actual execution environment. Once this host contract is installed, a new compatible plugin does not require plugin-specific host frontend compilation. Container delivery still needs a persistent package installation or an image containing the package.

Browsers retain their discovered plugin set until manual refresh; there is no automatic refresh or hot-unload guarantee. Old UI does not guarantee old backend code is retained across a service restart. A changed asset revision or removed action fails explicitly and requires reload. Disabled/unloaded pages have no navigation entry after refresh; visiting an unavailable page directly does not mount a plugin.

Validation scope

The bookmark E2E test runs the production frontend against real Python action handlers and SQLite, with synthetic authentication and scripted LangGraph ToolNode calls. It covers persistence, owner isolation, read-only deployment management and the full page workflow. It does not claim live model behavior or a full production deployment. The example uses single-host storage, not a multi-node persistence contract.

plugin-assets.spec.ts also checks authenticated static/lazy imports, CSS and images, plus direct SVG navigation through the real Gateway asset route. Its script-execution control removes the sandbox header from the same SVG to verify the restriction. To exercise the actual Turbopack development build, start the frontend with DEER_FLOW_DEV_BUNDLER=turbo pnpm dev, then run PLAYWRIGHT_SKIP_WEB_SERVER=1 pnpm exec playwright test tests/e2e/bookmark-plugin.spec.ts. Set PLAYWRIGHT_BASE_URL if the development server uses a port other than 3000.