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Claude Code 2.1.300 adds virtualText to prompt decorations and an AWS advisor
Claude Code 2.1.300 adds prompt virtual text, split cache-write metrics, an agent-transcript view API, and AWS /advisor.
Searcher → Analyst → Writer → Editor · subagentic-20261014-202641
Claude Code 2.1.300 was published on October 14, 2026, at 18:24:25 UTC. The release adds virtualText to a mod's prompt decorations, and it adds $.ui.view({ agentId }) to show an agent transcript. The agent.spawn hook can now rewrite a workflow agent's prompt and model. OpenTelemetry api_request events split cache writes by lifetime, and /advisor is available on Claude Platform on AWS.
virtualText that never enters the prompt
virtualText is text drawn in the prompt box that never enters the draft or the submitted prompt. It was added to a mod's prompt decorations.
A dir prop on a mod's Text supports right-to-left text. On Windows and in VS Code's terminal, its rows read in that direction and sit flush right.
The prompt.change mod hook is raised when the prompt box's text changes without a typed edit: a recalled history entry, a clear, an undo, or a plugin's fill.
An agent transcript view, and a spawn hook that can rewrite
$.ui.view({ agentId }) shows an agent's transcript in the main view when you ask. $.ui.view({}) goes back.
The agent.spawn mod hook can rewrite a workflow agent's prompt and model. Before this, the hook could only refuse workflow agents.
An advisor that stays idle
/advisor is available on Claude Platform on AWS. No advisor runs until you pick one with /advisor, advisorModel or --advisor. CLAUDE_CODE_DISABLE_ADVISOR_TOOL=1 turns it off.
Finer cache and span fields
OpenTelemetry api_request events now include cache_creation_5m_tokens and cache_creation_1h_tokens, splitting cache writes by lifetime.
Trace spans now include OpenTelemetry GenAI semantic-convention attributes, such as gen_ai.provider.name, gen_ai.conversation.id, gen_ai.tool.name and error.type.
In VS Code, claudeCode.attachSelection stops text selected in the editor from being added to your messages.
Read the v2.1.300 release notes before you call $.ui.view or rely on the updated agent.spawn hook. If you decorate prompts, try virtualText on a session you already run. On Claude Platform on AWS, leave the advisor unset until you choose one with /advisor.