Claude Code v2.1.251

What's changed

• Added PreModelSwitch and PostModelSwitch hook events (block, confirm, or annotate a model switch); SessionStart resume hooks now receive session staleness and the estimated re-cache cost
• Added live streaming of a foreground subagent's tool calls and results to Remote Control clients (background subagents, the default, still show status only)
• Added a Spend limit bar to /usage and a rate_limits.spend_limit status line field for developers behind a Claude apps gateway with spend limits
• Added a per-session prompt-cache line to /cost (hit ratio, misses, tokens re-cached, warm/cold) and a matching prompt_cache object for status line scripts
• Added attach, logs, stop, respawn, and rm to claude --help; the --resume message for a running background session now names the exact claude attach <id> command
• Fixed file tools (Read, Write, Edit) following a symlink swapped inside the working directory after the permission check, which could read or write outside the approved location
• Fixed plugin commands declared in a marketplace entry being able to point outside the plugin directory; such paths are now rejected with a path-traversal error
• Fixed project settings being able to enable detailed beta tracing or raw API body logging, and a lower-scope beta tracing endpoint bypassing an OTLP collector pinned by managed settings or a host app
• Fixed the Workflow tool reading (and quoting in errors) a scriptPath outside what the session may read before the permission check ran
• Fixed Grep and Glob not applying Read(...) deny rules to files reached through a symlinked search path
• Fixed conversations getting stuck on "text content blocks must be non-empty" errors after a turn where the model produced only thinking
• Fixed the first launch on a fresh install starting in default mode instead of auto mode for accounts whose startup default is auto mode
• Fixed Opus 5 requests failing with "effort … is not supported when thinking is disabled" when effort was xhigh/max and thinking was turned off; effort is now sent as high in that case
• Fixed replying to a message Claude Desktop delivered from another session: SendMessage to that session id now delivers through Claude Desktop instead of failing with "not reachable"
• Fixed TUI lag with many parallel subagents: per-second progress ticks now replace their predecessor instead of piling up in the transcript
• Fixed agent teams: a teammate's final answer not reaching the team lead — it now arrives in the idle notification instead of a content-free "available" notice
• Fixed background subagents being unable to reply to a message from an unnamed sibling or parent agent (from was the agent type, which is not an address)
• Fixed managed-settings disableAutoMode arriving mid-session not moving an already-running auto-mode session back to default mode
• Fixed a "switch to Opus 1M for 5x more context" tip that appeared even when the current Opus model already has a 1M context window
• Fixed Claude apps gateway sessions treating a stored Anthropic profile (e.g. a Console sign-in) as active: listing it in /status and retrying gateway 401s with it, though requests never use it
• Fixed cloud sessions telling Claude the model had changed when the host was only setting the session's initial model
• Fixed Remote Control reporting a failure when an organization's policy disables it; it now shows a single quiet notice instead
• Fixed /mcp reconnect on Remote Control showing a generic withheld-detail error instead of the real remedy when a server was disabled in another session
• Fixed --input-format stream-json: client-injected assistant tool calls sent without a message id were merged into the first one and their results lost, including when resuming older sessions
• Fixed session transcripts being silently overwritten when a directory change relocated a session onto an existing same-ID transcript
• Fixed background sessions and their sub