Removes the release-candidate framing from the docs for the 4.5 GA: the
`@rc` install caveats on the `skills` CLI command, and the AI Agents and
Prompts release-candidate banner (a shared snippet used across the
ai-chat and prompts pages) plus the `>=4.5.0-rc.0` compatibility pin in
the AI reference.
## Summary
Documents the two lower-level chat backend APIs and restructures the
Building agents section so it has a sane reading order.
**Custom agents page.** `chat.customAgent()` was effectively
undocumented (one passing mention) and `chat.createSession()` was buried
at the bottom of the Backend page, prompted by a customer asking whether
dropping down a level was supported at all. Both now live on one
dedicated page framed as a composition: register with `customAgent`,
then drive turns with the managed `createSession` iterator or a
hand-rolled primitives loop. The page covers the patterns the managed
lifecycle otherwise handles for you, each verified against a running
agent: seeding history on continuation runs (and why the seed must go
through the turn-0 `addIncoming`, which replaces the accumulator),
persisting the user message before streaming so a mid-stream reload
keeps it, racing `totalUsage` after a stop so the loop cannot wedge, and
the single-message wire shape.
**Backend page.** Now leads with a decision table across the three
abstraction levels and focuses on `chat.agent()`, routing to the new
page. Stale examples that read a plural `messages` field off the wire
payload are fixed (copy-pasting them broke turn accumulation), and the
ChatSessionOptions / ChatTurn reference tables gain their missing rows
(`compaction`, `pendingMessages`, usage fields, `setMessages`,
`prepareStep`).
**Anatomy page + reorder.** The Building agents group opened with the
long How it works mechanics page, a wall right after the Quick Start. A
short Anatomy page now leads the group: the three moving parts, one
annotated example where each region names the page that covers it, and a
routing table. How it works moves to the end of the group as the depth
payoff, matching where peer docs put their internals pages.
All pages visually verified against a local Mintlify build; cross-links
and anchors updated across the section.
## Summary
Documents the new `tools` option on `chat.agent` (companion to #3790).
Adds a dedicated [Tools](/ai-chat/tools) guide: the three places tools
show up (config, `toStreamTextOptions`, `streamText`), why declaring
them on the config matters for `toModelOutput` across turns, static vs
per-turn tools, the typed `run()` payload,
`InferChatUIMessageFromTools`, the relationship to skills, and the
manual `convertToModelMessages` path for `customAgent` loops.
Threads the option through the rest of the guide: the reference tables,
a happy-path section on the backend page, the types page, and the HITL /
skills / tool-result-auditing patterns. Corrects the sub-agents guide,
where the `toModelOutput` compression was implied to work across turns
but silently degraded from turn 2 without config tools.
Also unstacks the three callouts that were piled under the
`chat.agent()` header on the backend page, and adds a changelog entry.
Eric Allam