ModelPort

Model Guide Index

Registry of dedicated model guides. Read this first: find the source and target model, open the guide, then follow its upgrade path.

Status values: current (default target), active (still served, not the default target), legacy (superseded guide kept for layered upgrades).

Anthropic

Model	Model ID	Guide	Status
Claude Fable 5.1	claude-fable-5-1	claude-fable-5-1.md	current (opt-in only)
Claude Opus 5.5	claude-opus-5-5	claude-opus-5-5.md	current (default Opus target)
Claude Sonnet 5.5	claude-sonnet-5-5	claude-sonnet-5-5.md	current
Claude Haiku 5.5	claude-haiku-5-5	claude-haiku-5-5.md	current
Claude Opus 4.8	claude-opus-4-8	claude-opus-4-8.md	legacy (layer under Opus 5.5)
Claude Opus 4.6	claude-opus-4-6	claude-opus-4-6.md	legacy
Claude Sonnet 4.5	claude-sonnet-4-5	claude-sonnet-4-5.md	legacy

Claude upgrade paths. Apply each step in order, then the target guide.

If you are on	Target	Path
Opus 4.x or older	claude-opus-5-5	claude-opus-4-6.md, claude-opus-4-8.md, then claude-opus-5-5.md
Opus 5	claude-opus-5-5	claude-opus-5-5.md
Sonnet 4.x or older	claude-sonnet-5-5	claude-sonnet-4-5.md, then claude-sonnet-5-5.md
Sonnet 5	claude-sonnet-5-5	claude-sonnet-5-5.md
Haiku 4.5 or older	claude-haiku-5-5	claude-haiku-5-5.md
Fable 5	claude-fable-5-1	claude-fable-5-1.md

Default target when the user says “latest Claude model” and names no tier: claude-opus-5-5.

OpenAI

Model	Model ID	Guide	Status
GPT-6 Astra, GPT-6.1 Sol, GPT-6 Sol, GPT-6 Luna	gpt-6-astra, gpt-6.1-sol, gpt-6-sol, gpt-6-luna	gpt-6.md	current
GPT-5.5	gpt-5.5	gpt-5-5.md	legacy (layer under GPT-6)

Google

Model	Model ID	Guide	Status
Gemini 3.8 Flash	gemini-3.8-flash	gemini-3-8-flash.md	current

Not covered

No dedicated guide: other providers, open-weight models, older Gemini releases. Use ../provider-checklists.md, then research (see “Freshness” below).

Freshness

Every guide carries a Last verified: date and a Source: line. Model facts (IDs, prices, defaults, deprecations) change faster than guides do.

• Guide verified within 30 days of today: trust it, still smoke test.
• Older than 30 days, or the target model is missing from this index: fetch the provider’s official migration page before editing. Record the page and date in the migration report.
• Facts from secondary sources are marked as such in the guide. Confirm them on the provider page before quoting prices or dates to the user.
• After refreshing a guide, update its Last verified: line and this index.

Official sources:

• Anthropic: models overview and model deprecations
• OpenAI: Using GPT-6 and the models page
• Google: Gemini models and the Gemini API changelog

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