claude-sonnet-4-5
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.
Writing a file you have not read is now decided locally by model and permissions, not a server flag.
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.228.
In the changelogs
14Releases whose published page names claude-sonnet-4-5.
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v2.1.295
Proxy model-list warnings now cover every provider and catch typos
Warnings about upstream model lists in proxy settings now apply to every provider, accept wildcards, and flag entries that match no usable model
found in this entry's text
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v2.1.293
Haiku model names now go through the third-party Sonnet default check
On third-party providers, Haiku model names are no longer skipped by the check that sets up the Sonnet default model
found in this entry's text
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v2.1.284
Sonnet 5.5 added and made the default for the
sonnetmodel nameSonnet 5.5 (
claude-sonnet-5-5) is now in the model list and is whatsonnetpicks when using Anthropic directlyfound in this entry's text
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v2.1.284
The sonnet model name now points to Sonnet 5.5 on the Anthropic API
Choosing sonnet now selects Sonnet 5.5 instead of Sonnet 5 on the Anthropic API, while Bedrock, Vertex and other providers keep older models
found in this entry's text
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v2.1.284
Gateway model list marks 1M-context models, and telemetry export can use Google sign-in
The gateway now flags which models support the 1M context window, and telemetry export gains an
auth.googleoption for Google access tokensfound in this entry's text
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v2.1.283
The Sonnet 1M-context check now covers full Sonnet model names
Switching to any Sonnet model name ending in [1m] now checks for 1M-context access, except four older Sonnet models
found in this entry's text
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v2.1.236
ANTHROPIC_DEFAULT_MODELsets the model when nothing else doesSet ANTHROPIC_DEFAULT_MODEL and it becomes your model whenever no flag or ANTHROPIC_MODEL applies.
found in this entry's text
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v2.1.232
The managed-configuration schema and Zod 4 are bundled into the CLI
The full Claude Desktop managed-config schema, covering MCP policy and egress limits, is now bundled in.
found in this entry's text
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v2.1.228
Write-before-Read rule is now decided locally, not by a remote flag
Writing a file you have not read is now decided locally by model and permissions, not a server flag.
found in this entry's text
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v2.1.201
claude-sonnet-5 added to model compatibility list
found in this entry's text
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v2.1.195
Vertex 1M Context Warning for Unsupported Models
found in this entry's text
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v2.1.51
Model Selector Version Hints
found in this entry's text
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v2.0.59
Extended Thinking Mode for claude-opus-4-5
found in this entry's text
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v2.0.0
Claude Sonnet 4.5 Model
found in this entry's text
First cited
2The earliest release whose published evidence quoted claude-sonnet-4-5 was v2.1.232, 13 Aug 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.
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.