feat(server): Grok Build effort, auth, rewind, and usage [WIP - for content]

[t3dotgg]

Grok Build already exposes reasoning effort, login state, rewind, and token usage. T3 ignored all of that. You could not pick effort, a logged-out CLI still looked ready, and model changes forced a new thread.

T3 now reads the live Grok effort menu from ACP model _meta, sends session/set_model with _meta.reasoningEffort, and lets you change model or effort on the current thread. ACP login failures show as unauthenticated. Conversation rollback uses _x.ai/rewind. Prompt usage is emitted as thread.token-usage.updated. There is a Grok user guide.

Made with Grok 4.6.

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Note

Medium Risk
Changes Grok session lifecycle (model/effort switching, rewind mutating provider and in-memory turns) and auth probing; scope is Grok-only but rollback and turn trimming affect conversation integrity if mis-targeted.

Overview
Wires Grok Build into capabilities the CLI already exposes but T3 previously ignored: reasoning effort, login state, conversation rewind, and per-prompt token usage.

Reasoning & models: Effort menus come from ACP model _meta; the composer gets a Reasoning option (with fallbacks when discovery is thin). Selection is applied via session/set_model with _meta.reasoningEffort, optional --reasoning-effort at spawn, and in-thread model/effort changes (requiresNewThreadForModelChange is now false). Effort is not carried across a model switch unless explicitly requested.

Runtime behavior: After each prompt, usage from Grok metadata is published as thread.token-usage.updated. rollbackThread calls _x.ai/rewind/points / _x.ai/rewind/execute and trims local turn history. Provider status distinguishes unauthenticated Grok from other ACP failures and surfaces API-key vs session auth when discovery succeeds.

Supporting changes: setSessionModel accepts optional _meta; the ACP mock agent simulates rewind, usage, and effort metadata for tests. User docs add providers-grok.md; default text model for Grok is grok-build.

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Note

Add Grok Build reasoning effort, auth detection, rewind, and token usage support

• Adds reasoning effort selection to Grok sessions: the spawned CLI receives a --reasoning-effort flag, model capabilities expose a Reasoning selector, and applyGrokAcpModelSelection can switch effort without changing model.
• Implements rollbackThread for Grok using the _x.ai/rewind ACP extension: fetches rewind points, selects a target by turn count, executes the rewind, and trims in-memory turns.
• Extracts token usage from prompt _meta and publishes thread.token-usage.updated events after each turn.
• Auth detection in checkGrokProviderStatus now distinguishes API key vs. session auth and surfaces unauthenticated on ACP auth failures via isGrokAcpAuthFailure.
• Sets requiresNewThreadForModelChange to false and defaults the Grok provider model to grok-build.
• Adds a user-facing providers-grok.md guide covering login, model selection, reasoning effort, and troubleshooting.

^{Macroscope summarized 39ed592.}