claude-opus-4-8
A Claude Code model, read out of the shipped bundle. No mined inventory carries it: everything below comes from what this site has written about it.
Opus 5 is now the default Opus, with a 1M-context option in the model picker.
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.219.
In the changelogs
25Releases whose published page names claude-opus-4-8.
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v2.1.290
/code-review mediumnow runs the high-effort recipe on most modelsOn every model without its own
/code-reviewrow, Opus 5.5 included,mediumnow runs the eight-angle high recipe instead of a single pass.high,xhighand Opus 5 are unchanged.found in this entry's text
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v2.1.284
Refused requests on Sonnet 5.5 now fall back to Sonnet 5
When a Sonnet 5.5 request is refused as cyber or frontier_llm, Claude Code now falls back to claude-sonnet-5 instead of an Opus model
found in this entry's text
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v2.1.280
New cheaper cost table for claude-opus-5-5
A new, cheaper token-cost tier now applies to the claude-opus-5-5 model id
found in this entry's text
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v2.1.280
Future model IDs (opus-4-6, opus-4-7, opus-4-8, sonnet-4-6) added to model-recency comparison list
Model-recency list gains claude-opus-4-6, claude-sonnet-4-6, claude-opus-4-7 and claude-opus-4-8
found in this entry's text
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v2.1.280
Safety-classification model routing table gains a 'frontier_llm' entry
Safety-classification model routing gains a new 'frontier_llm' category mapped to claude-opus-5
found in this entry's text
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v2.1.280
mid_conversation_system opt-out model list simplified to a version comparator
Mid-conversation system prompt opt-out now uses a version comparison instead of a fixed model-name list
found in this entry's text
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v2.1.280
New models are unpinned from launch-time forced effort by default; existing installs stay pinned
Newly launched models like claude-opus-4-7 and claude-fable-5 stay pinned to a launch effort level unless unpinned, but only on installs that predate this build
found in this entry's text
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v2.1.248
Model tables extended to Opus 4.7, 4.8 and Opus 5
Model tables now list claude-opus-4-7, claude-opus-4-8 and claude-opus-5.
named in this entry, found in this entry's text
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v2.1.248
Per-surface context limits for claude-sonnet-5
Context limits for claude-sonnet-5 are 500,000 on two surfaces and a million elsewhere.
found in this entry's text
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v2.1.248
Unreleased Mythos and next-generation model ids in the bundled tables
Model tables carry ids for a Mythos preview and a 5-series family, not selectable.
found in this entry's text
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v2.1.246
The claude-api skill's documents moved out of the bundle, unchanged
The claude-api skill's documents moved to separate files with identical content and paths.
found in this entry's text
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v2.1.246
Opus 4.8 hands off to a fresh session much earlier
On Opus 4.8, sessions hand work off to a fresh session far sooner; Sonnet 5 is unchanged.
found in this entry's text
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v2.1.238
Safety-classifier severity scoring extended to two more sites, both inert here
The safety classifier can score severity at agent handoff and sandboxed network access, but both stay silent.
found in this entry's text
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v2.1.220
Opus 5 is skipped when the client cannot see model entitlements
If your session has no model access info cached, Claude won't fall back to Opus 5.
found in this entry's text
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v2.1.220
Refusal fallback no longer picks Opus 5 when entitlements are unknown
When a refusal triggers a model switch and entitlements are unknown, you get Opus 4.8 instead of Opus 5.
found in this entry's text
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v2.1.219
Opus 5 replaces Opus 4.8 as the default Opus model
Opus 5 is now the default Opus, with a 1M-context option in the model picker.
found in this entry's text
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v2.1.219
Bundled Claude API skill docs rewritten around Opus 5
The bundled Claude API skill docs now target the new Opus, covering thinking defaults, fallbacks and fast mode.
found in this entry's text
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v2.1.219
The API skill's model placeholders now resolve to Claude Opus 5, with the previous Opus kept as a separate placeholder
The API skill's model placeholders now render Opus 5, keeping the previous Opus named separately.
found in this entry's text
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v2.1.219
Model-downgrade chain and effort tables know about Opus 5
Model fallbacks and reasoning-effort settings now handle Opus 5, stepping down to Opus 4.8 when needed.
found in this entry's text
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v2.1.219
Opus 5 wired through region env vars, refusal fallbacks and pricing copy
An Opus 5 model is wired through region variables, fast mode, 1M context and pricing text.
found in this entry's text
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v2.1.207
Default Model Upgraded to Claude Opus 4.8
found in this entry's text
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v2.1.206
Refusal Category Fallback Routing
found in this entry's text
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v2.1.197
Model Documentation Updated in API Reference Context
found in this entry's text
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v2.1.195
Model Catalog: New and Updated Models
found in this entry's text
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v2.1.182
Legacy Model Remapping — Clearer Warning and Opt-Out
found in this entry's text
First cited
8The earliest release whose published evidence quoted claude-opus-4-8 was v2.1.197, 30 Jun 2026. That is the oldest release this project wrote about it, so it is a floor on the name's age and not the release that introduced it. It is not a presence reading: which builds carried the name is the table below.
2 further spans in the ledger name it. The list above is the earliest first and stops at 6.
Presence across releases
0The miner has never read a build containing this name. It is here because a changelog entry of ours names it, which is evidence that it existed and not evidence of which releases carried it. The inventory starts at v2.1.138 and everything older than that was never mined.
Read out of the published npm bundle release by release, and out of Anthropic's own documentation as this site captured it. Nothing on this page is a description anybody here wrote about what the model does. All models.