docs(agent-plugin): add install guides for the Arcade agent plugin

[teallarson]

Closes GRO-303.

Important

DO NOT MERGE / KEEP DRAFT. The plugin repository and production gateway are live, but the GRO-309 launch and marketing gate still needs explicit verification. Keep this PR gated until that approval is confirmed and Teal authorizes removing the gate.

Adds a Get Started section for installing Arcade through the agent plugin. The install paths and support matrix are synced to the released arcade-plugin v0.2.1 documentation.

Pages

app/en/get-started/agent-plugin/ sits second in Get Started as the personal-use path that needs no gateway or API-key setup before installation.

• Overview — client-native installation for Claude Code, Codex and ChatGPT local, Cursor, VS Code, Copilot CLI, and Claude Desktop; the released support matrix; sign-in; and sample prompts
• Claude Desktop — plugin marketplace and tools-only connector options, plus the Chat versus Cowork and Code capability split
• Any MCP client — the production Streamable HTTP gateway URL for OpenCode and other MCP clients
• From trial to team rollout — the path to a dedicated gateway, curated tools, and organization-managed end-user identities

The overview uses tabs because the client-specific install content is short and belongs beside the capability matrix. Existing MCP client guides continue to document a gateway you control and point personal-use readers to the plugin where applicable.

Released installation paths

The cross-client npx plugins add command does not finish every supported client install in v0.2.1, so the page now uses the client-native paths from the released source:

• Claude Code and Codex use their native marketplace commands.
• Cursor individual installs clone into Cursor's local plugin directory; Teams and Enterprise use a team marketplace import.
• VS Code uses Chat: Install Plugin From Source and chat.plugins.enabled.
• Copilot CLI uses copilot plugin install.
• Claude Desktop uses Customize → Plugins → Add marketplace.

The commands were source-checked against the released v0.2.1 documentation, not tested against the user's installed clients. Repository-based install commands are not release-pinned and can resolve newer repository content.

Completed fixes cover native Desktop and client-specific installation and connection guidance, Codex skill invocation, required permissions and possible reauthentication, and organization identity providers only when the organization uses one. Fallbacks require authorization and stop on sign-in or permission denial. App-connection identity wording now describes the verified connection identity rather than making unsupported absolute isolation claims.

Current plugin state

Current plugin main is 6f4cdc7695b1953cdb2b7d207e53e5abb9738d1c, including merged #26's hard-disabled telemetry foundation; plugin package metadata remains v0.2.1. Adapter and reporting PRs #27, #28, and #29 remain unmerged, as does the proposed v0.3.0 release #30. No environment setting enables telemetry in the current build. Hosted gateway and app requests still occur.

Shared values

lib/agent-plugin.ts holds the two shared values:

export const AGENT_PLUGIN_GATEWAY_URL = "https://api.arcade.dev/mcp/arcade";
export const AGENT_PLUGIN_REPO = "ArcadeAI/arcade-plugin";

lib/remark-substitute.ts resolves those tokens in prose, inline code, fenced code blocks, and link targets, including the raw Markdown used by copy-page and agent-facing outputs. The obsolete universal install-command token was removed.

tests/broken-link-check.test.ts resolves the tokens before link validation so substituted URLs are not treated as relative paths.

Generated llms.txt

public/llms.txt contains current titles and useful descriptions for the install-guide and MCP-client pages changed here.

During readiness work, the generator's recorded base SHA was found to be missing from repository history. The current workflow treats that Git error as zero changed pages and reports success without regeneration. Its configured OpenAI key also returned 401 when generation was forced. Those are repository-wide generator reliability issues and are intentionally not fixed in this focused documentation PR; they need a separate follow-up with tests and an explicit decision about failing versus deterministic fallback behavior.

Because of that known issue, a green Generate LLMSTXT check on this PR is not evidence that regeneration occurred. Review the committed public/llms.txt diff directly.

Not included

• A .mcpb Desktop Extension. The v0.2.1 release intentionally installs Claude Desktop from the plugin marketplace and offers the production gateway as the tools-only connector path.
• Automatic installation. The docs describe and verify official commands but do not modify a reviewer's local client configuration.
• Generator infrastructure changes. The workflow and generator source match main; the reliability fix is saved separately for follow-up review.

Human review and release prerequisites

• Mateo's review asked for a plain-language explanation of what the plugin bundles. The opening paragraph now names the hosted gateway, two skills, three commands, and arcade-operator. His previous Changes requested review is now Dismissed, not an approval; its dismissal does not establish GRO-309 launch approval.
• GRO-309 launch and marketing approval remains the release gate even though the repository is public and https://api.arcade.dev/mcp/arcade is the production endpoint.
• Keep the PR draft until GRO-309 approval is confirmed and Teal authorizes removing the body launch gate.

Verification

• Current head: 4fee3995deb7c81f7947db536863b038ae4ebb6b; conflict resolution is complete.
• Independently verified exact-head GitHub job: lint, typecheck, build, and tests pass. Schema validation, redirects, external URL checks, and Vale also pass.
• Exact-head Vercel deployment completed successfully at 19:34 UTC.
• Independent source review found no blocking P1/P2 issues.
• Cloud desktop preview checks passed all six install tabs, the support table, privacy and fallback guidance, the Desktop link, and substituted commands. Clipboard verification was inconclusive.
• Cursor reported local tests with 885 passed and 2 skipped, a build with 303 pages, and mobile checks at 390 × 844 with no horizontal overflow. These are Cursor's reported results, not independently verified local or mobile results.
• No completed current-head Bugbot result was visible; no Bugbot pass is claimed.
• Generate LLMSTXT is green, but its log shows a bad base SHA and zero changed pages. This is not evidence that regeneration occurred; review the committed public/llms.txt diff directly.

Preview: Vercel deployment

— Strider 🐦‍⬛, Teal's agent · approved by Teal.

🤖 Originally generated with Claude Code; readiness cleanup updated with Codex.

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Project	Deployment	Actions	Updated
docs	Ready	Preview	Oct 12, 2026 7:34pm UTC

[torresmateo]

I like these docs with a small caveat.

I think we're introducing two things that look very similar to MCP gateways and if you're not deep in the weeds of what's a plugin vs a gateway vs a server things can spiral very quickly.

On the overview page, I think we need a sentence on the plugin overview page that explains what it is as clearly as possible, telling users the things that are bundled at the beginning of that page.

pat leave