Claude Code 2.1.300 Release

Added

• Added virtualText to a mod's prompt decorations: text drawn in the prompt box that never enters the draft or the submitted prompt
• Added cache_creation_5m_tokens and cache_creation_1h_tokens to the OpenTelemetry api_request event, splitting cache writes by lifetime
• Added $.ui.view({ agentId }) for mods: shows an agent's transcript in the main view when you ask, and $.ui.view({}) goes back
• Added a dir prop on a mod's Text for right-to-left text: on Windows and in VS Code's terminal its rows read in that direction and sit flush right
• Added /advisor on Claude Platform on AWS; no advisor runs until you pick one with /advisor, advisorModel or --advisor, and CLAUDE_CODE_DISABLE_ADVISOR_TOOL=1 turns it off
• Added OpenTelemetry GenAI semantic-convention attributes to trace spans, such as gen_ai.provider.name, gen_ai.conversation.id, gen_ai.tool.name and error.type
• Added support for rewriting a workflow agent's prompt and model in the agent.spawn mod hook, which could only refuse workflow agents before
• Added the prompt.change mod hook, 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
• [VSCode] Added the claudeCode.attachSelection setting to stop text selected in the editor from being added to your messages
• [Claude Tag] Added support for Slack Connect channels: an Owner or Claude Tag admin can let Claude in Slack answer in channels shared with another organization; it's off by default
• [Claude Tag] Added a private Allow once / Deny card in Slack threads for connector actions that need your approval, so Claude asks instead of refusing; others only see that it's waiting on you
• [Claude Tag] Added support for Slack voice clips in Claude in Slack: Claude reads Slack's transcript of a clip when Slack has one

Changed

• Changed CLAUDE_CODE_PROVIDER_MANAGED_BY_HOST sessions to ignore CA-bundle, tool-proxy, git TLS and git config variables like SSL_CERT_FILE in settings; under Claude Desktop, only in project settings
• Changed exit to force-kill background commands still running 1.5 seconds after being asked to stop; in fullscreen mode they could previously be left running
• Changed Claude Desktop's Code tab to apply managed settings when forceLoginGatewayUrl names an Anthropic-operated gateway that serves the session's hostname; that gateway must be reachable at start
• Changed claude gateway to stop at start, naming the key, on a desktop: policy key that Claude Desktop cannot use from a gateway, where it earlier started with a warning
• Changed large requests to api.anthropic.com to use gzip compression even when telemetry is disabled; set CLAUDE_CODE_GZIP_REQUEST_BODIES=0 to turn it off
• Changed the claude-api skill to leave Managed Agents sessions in place unless you ask to archive or delete them
• Changed background sessions to resume a carried workflow through the Workflow tool's approval instead of running it from the handoff file
• Changed local session transcripts to also record each API request's system prompt, tools and parameters, so a transcript you choose to share can reproduce a request exactly
• Changed the /sandbox mode options to read "Sandbox commands" instead of "Sandbox BashTool"
• Changed PermissionRequest hooks in Cowork cloud sessions: a setMode update in a hook's allow is now ignored; the rest of the approval still applies
• Changed hooks: updatedInput from PreToolUse and PermissionRequest hooks is now validated like Claude's own input: unknown keys are dropped, and input the tool rejects denies the call
• Removed the --sandbox and --no-sandbox flags from claude remote-control, which had no effect; passing either now exits with an error. Set sandbox.enabled in settings to sandbox sessions
• [Claude Tag] Changed access bundles an admin attached to a Slack channel to keep applying once the channel becomes a Slack Connect channel, with no need to remove and re-attach them

Improved

• Improved WebFetch in Cowork cloud sessions to tell Claude that a page failed moments ago instead of fetching it again
• Improved mod sharing in the built-in plugin-authoring skill: Claude scans a mod's files for keys before opening them, and asks before scanning a folder outside the project
• Improved the note Claude 3 models get about an @-mentioned PDF, so they less often answer without reading it
• Improved artifact updates: Claude now applies a small change and republishes the artifact in one call, and makes larger edits and republishes within a single response