docs: document built-in tool rate limiting [PLT-2390]

[iherdt]

What

Adds a public docs page for the Engine's built-in tool rate limiting under Contextual Access, plus navigation and cross-links:

• New page: app/en/operate/governance/contextual-access/rate-limiting/page.mdx
  • Rule anatomy: tool matchers (exact, Toolkit.*, *), limits, time windows (s, m, h, d, mo)
  • Enforcement semantics: fixed UTC-aligned windows, most-specific rule wins, per-tool and per-scope counters shared across users
  • What a rate-limited call sees (both the over-limit and unverified denial messages)
  • Dashboard walkthrough and API example (plugin_type: "rate_limit"), org and project scope
  • Fail-closed behavior and per-rule allow_on_unavailable
• Sidebar entry in _meta.tsx, card on the Contextual Access index, cross-link from Build Your Own

Why

Rate limiting shipped in the Engine and the Dashboard, but there was no public documentation for configuring it. Closes the docs gap tracked in PLT-2390.

Verification

• All factual claims checked against the Engine source (apps/engine/pkg/plugins/ratelimit/), API schemas, and route registration in ArcadeAI/monorepo
• Vale: 0 errors
• Full test suite passes (847 tests)

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Note

Low Risk
Documentation-only change; no product, auth, or enforcement code is modified.

Overview
Documents Arcade Engine built-in tool rate limiting so operators can cap tool calls without a webhook server.

The new Contextual Access page covers rule matchers (exact, toolkit, global), UTC-aligned windows, per-tool/per-scope counters shared across users, Dashboard and plugins API setup (plugin_type: "rate_limit"), and fail-closed behavior with optional allow_on_unavailable.

Also wires the page into the sidebar, the Contextual Access index, Build Your Own, and llms.txt.

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Project	Deployment	Actions	Updated (UTC)
docs	Ready	Preview	Aug 21, 2026 10:50pm