feat(models): add OpenAI GPT-5.6 sol/terra/luna

[smakosh]

Summary

Adds OpenAI's new GPT-5.6 family — released today (2026-07-09) — to the model catalog, with openai + azure provider mappings following the gpt-5.5 / gpt-5.4 pattern.

Model	Positioning	Input / 1M	Cached / 1M	Output / 1M
gpt-5.6-sol	Frontier reasoning, complex professional work	$5.00	$0.50	$30.00
gpt-5.6-terra	Balanced intelligence and cost	$2.50	$0.25	$15.00
gpt-5.6-luna	Cost-optimized, high-volume tasks	$1.00	$0.10	$6.00

Shared specs (verified against OpenAI's model pages and pricing page)

• Context window 1,050,000 tokens, max output 128,000 tokens
• Knowledge cutoff February 16, 2026
• Reasoning (reasoningOutput: "omit"), vision, tools, web search ($0.01/call), structured outputs, Responses API
• Service tiers: flex (0.5×) and priority (2× — verified against OpenAI's priority pricing table, so serviceTierMultipliers: { priority: 2 } overrides the provider default 2.5×)
• Azure mappings marked test: "skip", mirroring the rest of the GPT-5.x family

Also included

• Changelog entry 2026-07-09-gpt-5-6-models + OG image (gpt-image-2, house circuit-board style)
• Curated model category lists refreshed (coding, creative-writing, translation, math) with the new family
• Code landing showcase flagship swapped gpt-5.5 → gpt-5.6-sol

Testing

• pnpm build — 17/17 tasks pass
• pnpm test:unit — 150/150 files, 2441 passed
• TEST_MODELS="openai/gpt-5.6-sol,openai/gpt-5.6-terra,openai/gpt-5.6-luna" pnpm test:e2e — 107 passed against the live OpenAI API, all three models exercised (streaming, reasoning, tools, JSON, etc.)

https://claude.ai/code/session_01C1G9vcptkguozAPhQS9Xec

Summary by CodeRabbit

• New Features

  • Added support for the GPT-5.6 model family in the model catalog, including Sol, Terra, and Luna.
  • Updated coding, writing, translation, and math model recommendations to include the new GPT-5.6 options.
  • Published a new changelog entry highlighting the GPT-5.6 family and how to use it with the same API flow.

• Bug Fixes

  • Refreshed the featured coding model selection so the latest recommended model appears first.

[steebchen]

Images automagically compressed by Calibre's image-actions ✨

Compression reduced images by 71.4%, saving 1.5 MB.

Filename	Before	After	Improvement	Visual comparison
apps/ui/public/changelog/gpt-5-6-models.png	2.1 MB	608.7 KB	71.4%	View diff

[coderabbitai]

Walkthrough

Adds three new OpenAI model definitions (gpt-5.6-sol, gpt-5.6-terra, gpt-5.6-luna) with provider configs and pricing, wires them into category allowlists and the coding showcase's recommended models, and adds a changelog entry announcing the release.

Changes

GPT-5.6 Model Rollout

Layer / File(s)	Summary
New GPT-5.6 model definitions packages/models/src/models/openai.ts	Adds gpt-5.6-sol, gpt-5.6-terra, and gpt-5.6-luna to openaiModels with OpenAI and Azure (test: "skip") provider configs, pricing, context/output limits, and feature flags.
Category filter and showcase wiring apps/ui/src/lib/model-category-filters.ts, apps/code/src/components/CodingModelsShowcase.tsx	Adds new model IDs to coding, creative-writing, translation, and math category allowlists, and swaps gpt-5.5 for gpt-5.6-sol in the coding showcase's recommended models.
Changelog entry apps/ui/src/content/changelog/2026-07-09-gpt-5-6-models.md	Adds a changelog page announcing GPT-5.6 family availability, with pricing comparison table, shared capabilities, and a getting-started curl example.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• theopenco/llmgateway#2059: Both PRs extend the openaiModels registry in packages/models/src/models/openai.ts with new model definitions.
• theopenco/llmgateway#2076: Both PRs add new GPT model entries to openaiModels (gpt-5.5 vs gpt-5.6-*).
• theopenco/llmgateway#2431: Both PRs modify RECOMMENDED_MODELS in CodingModelsShowcase.tsx to swap recommended model entries.

Suggested reviewers: steebchen

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: adding the OpenAI GPT-5.6 sol, terra, and luna models.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/gpt-5.6-models

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