docs: add GPT-5.6 Sol and Terra to the predefined agent LLM models - #11440

• Gather context (PR diff, changed file, repo docs conventions)
• Understand the request (docs review)
• Review the change
• Post review

What changed: two entries appended to the OpenAI GPT list of predefined llm values in docs-mintlify/admin/ai/index.mdx:93-94.

- `gpt_5_4`
+ `gpt_5_6_sol`
+ `gpt_5_6_terra`
- `o3`

Assessment:

• Correct file — this is the active /docs-mintlify site, not the deprecated /docs. ✅
• Placement and ordering are consistent with the surrounding list: version-ascending within the GPT group, o* reasoning models still last. ✅
• Naming style matches the existing convention (lowercase, _-separated version, variant suffix), same shape as gpt_5_mini. ✅
• Surgical edit to an existing page rather than new content — matches docs-mintlify/CLAUDE.md guidance. ✅
• No new page, so no docs.json navigation update is needed. ✅
• Nothing security-, performance-, or test-related applies to a two-line list addition. No test coverage gap: these identifiers aren't defined anywhere in this repo (grep for gpt_5_4/gpt_5_3 matches only this doc page), so the enum is validated on the Cube cloud side.

One thing I can't verify from this repo: because the model identifiers live outside the monorepo, I can't confirm that gpt_5_6_sol and gpt_5_6_terra are the exact strings the platform accepts. Worth a quick check against the cloud-side enum before merge — a typo here would only surface as a runtime config error for users.

Optional, not blocking: the list doesn't indicate which models are available on which plan tiers or which are recommended defaults, so readers picking a model get no guidance. That's pre-existing and out of scope for this PR.

• Gather context (PR diff, changed file, docs conventions)
• Understand the request (docs review, re-run on synchronize)
• Check for stale review threads to resolve
• Review the change
• Post review

What changed — unchanged from my previous pass; the diff against origin/master is still exactly two appended list entries in docs-mintlify/admin/ai/index.mdx:93-94:

  - `gpt_5_4`
+ - `gpt_5_6_sol`
+ - `gpt_5_6_terra`
  - `o3`

Assessment:

• Correct file — the active /docs-mintlify site, not the deprecated /docs. ✅
• Placement and ordering match the surrounding list: version-ascending within the GPT group, o* models still last. ✅
• Naming matches the existing convention (lowercase, _-separated version, variant suffix), same shape as gpt_5_mini. ✅
• Surgical edit to an existing page — matches docs-mintlify/CLAUDE.md guidance on preferring small edits over new content. ✅
• No new page, so no docs.json navigation update needed. ✅
• Nothing security-, performance-, or test-related applies to a two-line list addition. No test-coverage gap: these identifiers aren't defined anywhere in this repo, so the enum is validated cloud-side.

Previously open question — now closed. I'd flagged that I couldn't verify the exact strings from this repo. @igorlukanin confirmed both keys match the cloud-side enum (PredefinedLLMProviders in cube-runtime#1112, predefined_llm in cubejs-enterprise#13569), and that this PR intentionally lands last of the three. Nothing left to check.

No unresolved review threads on this PR, so nothing to resolve or dedupe against.

Optional, not blocking and pre-existing: the list gives no signal about plan-tier availability or which model is the recommended default, so readers picking a model get no guidance. Out of scope here.