Claude Opus 4.5 and Sonnet 4.5 removed from /model selection, require launch flag
Anthropic has removed Claude Opus 4.5 and Sonnet 4.5 from the interactive /model selection menu within active sessions. This change affects users who previously could switch between models mid-session, particularly when managing token usage near context limits.
What changed
The /model command no longer lists Opus 4.5 or Sonnet 4.5 as available options during an ongoing session. Users discovered this when attempting to switch to less token-intensive models when approaching session context limits.
How to access older models
To use Opus 4.5 or Sonnet 4.5, you must now start a new session with the --model flag and specify the full model ID:
claude --model claude-opus-4-5-20250514
claude --model claude-sonnet-4-5-20250514The model ID format follows the pattern: claude-{family}-{version}-{date}. These older model IDs are not included in the /model picker interface and must be specified directly at session launch.
Practical implications
This change means you can't switch to these older models within an existing session. If you prefer using Opus 4.5 or Sonnet 4.5, you need to start fresh sessions with the appropriate flag. This affects workflow for users who regularly adjust model selection based on token consumption or specific task requirements.
📖 Read the full source: r/ClaudeAI
👀 See Also
Netlify CTO Dana Lawson: Writing Code Is No Longer the Job
Netlify CTO Dana Lawson argues that developer work shifts from writing code to orchestrating AI agents. Engineers become experience designers, curating agent outputs and managing system boundaries.
Persistent Data Loss in Claude Projects: Conversations Disappearing Without Recovery
A long-form writer reports losing entire days of work in Claude Projects due to conversations disappearing from the project chat list, unsearchable and unrecoverable, with no response from Anthropic support after three incidents.
Claude Shannon's 1950 Chess Paper Predicted GenAI's Core Problem: Guessing vs. Knowing
Shannon's 1950 chess paper framed the core challenge of AI: making 'tolerably good' decisions under uncertainty—exactly the problem generative AI faces today when it produces polished but wrong answers.
Granite 4.1: IBM's 8B Dense Model Matches 32B MoE in Benchmarks
IBM's Granite 4.1 8B dense model matches or beats the previous 32B MoE model on ArenaHard, BFCL V3, GSM8K, and more, thanks to improved training data quality.