Claude Code v2.1.285

Remote clients can get read receipts for messages they send to a session#

The remote connection can now report when an incoming message was read and track messages that arrive more than once

Unclear It is not clear what decides whether read receipts are offered for a given connection.

Code for handing off turns and connecting added MCP servers was reworked#

The code that hands a turn to another host, and that reports on MCP servers added during a session, appears in reworked form

Unclear This may be existing code that moved, and it is not clear whether any behaviour changed.

Remote session bridge reports read receipts and delivery#

The connection to remote sessions can now report when incoming messages are read and delivered, and flush streamed output sooner

Unclear What these new reporting options control for someone using a remote session is not clear.

Claude Code can now look up your computer's name#

Claude Code can now read the computer name, using macOS's own tool, the Windows COMPUTERNAME value, or the hostname elsewhere

Unclear Where the computer name is used is not clear.

Remote session control recognises a plugin connection request#

A list of remote-session request types now includes plugin_connect, and a broken check for tool_register was corrected

Unclear It is not clear what this list of request types controls.

Remote sessions hold settings steady while a device is attached#

Settings served to a remote session are frozen while a device is attached, and calls are now logged with their outcome

Unclear It is not clear whether this is active yet or what, if anything, a user will see.

Remote sessions record startup timing and artifact comment counts#

Remote sessions now measure how long a startup step takes, and queued-message reports count artifact comments

Internal additions for remote sessions#

Claude Code gains internal pieces for remote sessions that have no visible effect yet

Unclear How either new piece is used is not known.

Cancelling also clears a pending attach that was on hold#

Cancelling now also clears an attach that was being held, and a turn now waits for the session to settle before it starts

Unclear It is not clear what the held attach is or which kinds of session this affects.

Remote tunnel connections send a credential version and watch for lock changes#

Remote tunnel connections gain a header carrying a credential version, and a lock check now notices when the lock file has changed

Unclear It is not clear which feature uses the new header and lock check.

Remote sessions can track when the last full sign-in check happened#

Remote sessions gain bookkeeping for the time of the last full sign-in check before model requests, off unless a server value is set

Unclear What uses the recorded time, beyond keeping track of it, is not known.

A check for sessions started from claude.ai chat was revised#

Claude Code checks for sessions whose CLAUDE_CODE_SESSION_ORIGIN is claude_ai_chat together with a second condition

Unclear It is unclear what this check controls and what exactly changed in it.

Remote sessions can report their connection status to the server#

Remote sessions can now send their connection status to the server, not only a worker status

Unclear It is not clear whether the server does anything with the connection status yet.

Remote sessions track resumes and background tasks#

Remote sessions now note when a connection is a resume and report running background tasks

Unclear Where each of these is used, and whether anything gates them, is not clear.

Proxied cloud sessions change how they set up certificate trust#

The agent proxy now logs where its certificate authority comes from and runs a reconcile step when it comes from the environment

Unclear When the certificate comes from the environment rather than being fetched is not clear.

Bridge replies can now mark a resumed session#

Replies Claude Code passes along through its bridge now say when the session was resumed

Unclear Nothing yet shows what uses the two new names or whether the lists control what is allowed.

Remote connection setup retries now use shared timing with random spread#

When setting up a remote connection fails, the wait before retrying is now worked out by shared code with 25% random variation

Unclear Whether the actual waits differ from before is not clear.

Remote session sync no longer reports a direction#

Remote session sync status no longer includes a direction such as "through this computer"

Unclear What displays or uses this direction is not clear.

Waking a resumed remote session for restored background work keeps working the same way#

The two settings that decide whether a resumed remote session wakes for restored background agents and shells are still read, both falling back to on

Unclear It is not clear whether this build changes how these settings behave at all.

Usage data now records how long an API request takes to prepare#

Claude Code's usage data now includes how long it took to prepare each request before sending it

Request timing data now includes more of Claude Code's own overhead#

Usage data about each request to the model now records extra timing figures about Claude Code's own overhead

Tool summaries marked as tool-free helper requests, and more detail on denied prompts#

Requests that write short summaries of tool use are now marked as tool-free helpers, and usage reports on denials note unanswered prompts

Unclear It is not clear whether marking the summary request as tool-free changes how that request runs, or only how it is labelled.

Usage reporting for pinned memory files sends less information#

When a memory file is pinned, the usage report no longer reads the file or includes its pinned state

Home-directory recovery telemetry records whether it ran after an announced run#

Usage data sent when the home-directory setup recovers now also records whether recovery came after an announced run

Latency telemetry for non-interactive runs now measures each round#

Speed data from non-interactive runs now records each round of model requests separately, not just one total per turn

Unclear It is not clear whether this data is sent for every run or only for a sample.

Login refused by sign-in provider now recorded apart from organization refusals#

When login is refused because the sign-in provider is not allowed, Claude Code records that separately from refusals by the organization

Unclear It is not clear what causes a login to be refused with provider_not_allowed.

Claude Code now times how long image resizing takes#

Claude Code now measures how long it takes to resize an image and to shrink it to fit a size limit

Unclear It is not clear where these timings are reported.

Usage data labels model restrictions as coming from an allowlist more often#

A check in how Claude Code reports where a model restriction came from now always gives the same answer

Unclear Whether this check is newly disabled in this release is not established.

Internal reporting on why parts of a request miss the prompt cache#

Claude Code now measures and reports internally why the end of a conversation is left out of the prompt cache

Unclear It is not clear where this reporting is sent or whether a switch controls it.

Detection of sign-in forwarded over SSH now checks for a placeholder#

Claude Code recognises SSH-forwarded sign-in when a socket is set and exactly one credential variable holds the value ssh-placeholder

Unclear It is not clear which part of Claude Code acts on this check.

Foundry connections identify themselves with their own name#

Requests Claude Code sends through its Foundry connection now identify themselves as AnthropicFoundry/JS

Remote tool calls handle approvals that arrive after a stop more carefully#

When Claude runs tools remotely, an approval that arrives after a stop is now recorded, and the end of the work waits for pending questions

Unclear It is not clear whether this changes anything a user would notice.

Stricter directory listing on Linux#

On Linux, a new directory listing refuses links, unusual paths and folders blocked by read rules, and caps how many entries it returns

Unclear It is not known which feature uses this listing or whether it is switched on.

Write tool instructions drop a separate warning for files outside your project folder#

The Write tool's instructions no longer carry a special warning about files outside the working directory and simply say overwriting an unread file fails

Unclear It is not clear when the removed wording was shown, since the stock Write description captured under this release is unchanged from the previous one, and whether the tool itself behaves differently.

Handling of the --tools flag reorganized, with the same warnings#

The code that reads --tools and warns about unknown tool names was moved into one place; the warning text is unchanged

Unclear The typo warning may now be skipped for some names that appear in a particular list, which would be a small behaviour change.

Streaming checks for Anthropic, gateway and AWS providers are shared#

Claude Code now handles streamed replies from Anthropic, gateways and Anthropic on AWS through one shared check, and the Bedrock guard is unchanged

Unclear Some requests now also record a timestamp, and what it is used for is not known.

A request can now list the built-in tools#

One of Claude Code's requests now includes a list of built-in tools when one is provided

Unclear It is not clear which request carries this list or what supplies it.

Cloud sessions check this computer's session records differently#

A cloud session running without a window now checks this computer's session records only when a condition allows it

Unclear What decides whether the check runs, and what it means for you, is not known.

Turn limits and built-in tool lists are now passed along with session options#

When Claude Code passes on session options, it now includes the turn limit and the built-in tool list when they are set

Unclear Which part of Claude Code receives and uses these options is not stated.

Shorter schema description for the cloud session directory_sync field#

The schema text for directory_sync now points to a separate document instead of explaining its states inline

Clearer warning when a session record lookup fails#

A logged warning about searching other project folders for a session's record now says plainly what could not be determined

A turn limit is now passed along with a request when one is set#

When a maxTurns turn limit is set, Claude Code now sends it along with a request instead of leaving it out

Unclear Which request now carries the turn limit is not settled.

Cloud file downloads now record why they fail and how long steps take#

Downloading files in cloud sessions now records failure reasons and timings for image preparation, writing and hashing

Unclear Where these totals are sent was not established.

Browser MCP server setup now runs a bundled Playwright script#

Claude Code can build a browser MCP server that runs a bundled Playwright script with node and sets CLAUDE_TEST_PROJECT_DIR

Unclear It is not clear what switches the browser server on or where it is used.

New names for MCP connections and appending to a session#

Three new names appear for connecting to MCP, appending to a session and a plain MCP server call, next to existing ones

Unclear What uses these names and whether anything restricts them is not clear.

MCP tool calls made from task code can now connect to a server#

The link that lets task code call MCP tools can now also connect to a named MCP server, and one callback's errors are logged and ignored

Unclear How this new connect ability is exposed to users is not clear.

Connecting an MCP server now fails cleanly if it leaves the session first#

If an MCP server is removed before it finishes connecting, the connection attempt now reports a failure

Unclear It is not clear which parts of Claude Code use these new connection steps.

MCP discovery cache now limited to dynamic toolbox servers in cloud sessions#

With MCP_DISCOVERY_CACHE on, only dynamic toolbox HTTP servers in cloud sessions that send two identifying headers can use the cache

Schema conversion library updated#

The bundled zod library was updated, changing how some tool and MCP schemas are converted to and from JSON Schema

Invalid multipleOf values are reported instead of written into JSON Schema#

A multipleOf divisor of zero or a non-finite number now produces an error instead of being written into a JSON Schema

Updated data validation library changes some schema checks#

Claude Code ships a newer version of Zod, the library that checks data shapes, with small changes to validation and JSON Schema output

Bundled validation library can check MAC addresses and credit card numbers#

The library Claude Code uses to check data formats now recognises MAC addresses and credit card numbers

Bundled data validation library updated#

The library Claude Code uses to check that data has the right shape was updated, with little visible effect

Sandbox file storage gains directory listing and an optional sync-on-write#

The sandbox's file storage on Linux, macOS and Windows can now list directories and optionally flush files to disk as they are created

Unclear What turns the write-through option on is not clear.

The sandbox check for disableNoSandbox gains an extra condition#

A sandbox check can now pass on a new condition before it looks at the disableNoSandbox setting

Unclear What the new condition tests, and what passing this check allows, are not clear.

Sandbox keeps extra track of symbolic links#

The sandbox now keeps two more lists about symbolic links, though what uses them is not yet visible

Unclear What reads these lists, and so what they change in practice, is not established.

Sandbox package registry defaults now come from a shared list#

The sandbox's default allowed package registries, such as registry.npmjs.org and pypi.org, now come from a shared list

Unclear It is not clear which hosts the shared list contains.

Startup telemetry notes early feature-setting fetches on a warm wake#

Startup telemetry for waits on remote feature settings now records whether the fetch started early on a warm wake

Unclear It is not clear what the tengu_cobalt_thicket gate itself controls.

Two startup waits are now timed and logged#

Claude Code now logs and measures how long it waits at startup for the model list refresh and MCP policy settings

Changed list of startup flags Claude Code singles out#

Claude Code now keeps a set of startup flags, including --print, --background and --version, that it treats as a group

Unclear How Claude Code uses this set of flags at startup is not shown.

More detailed timing of session startup#

Claude Code now measures how long each part of starting a session takes, for internal diagnostics

Unclear Where these timings are sent is not known.

Removed and discarded queued commands are tracked more precisely#

When a queued command is removed, its log entry now includes an ID, and discarded commands pass through an extra step

Unclear It is not clear what the extra step for discarded commands does.

Two kinds of background hints no longer hide each other#

Background hints marked key-only are now de-duplicated separately, so both kinds can appear in one run

Unclear It is not clear what a keyOnly hint shows in the interface.

Queued commands can now carry an ID in the session log#

Records of queued commands in the session log can now include an ID for the command

Unclear It is not clear which parts of Claude Code fill in the command ID.

Losing sign-in partway through a session counts as a temporary feature-flag failure#

When sign-in is lost mid-session, fetching feature settings now treats it as a temporary failure rather than a lasting one

Unclear It is unclear what a user would notice differently when sign-in is lost during a session.

Startup wait for feature settings reorganised and now recorded#

How Claude Code decides whether to wait for feature settings at startup was reorganised, and the wait is now recorded

Unclear It is unclear whether how long startup waits has itself changed.

An internal feature now follows a different server-side switch#

A feature that followed one server-side switch now follows a differently named one, still on by default when the server sends nothing

Unclear It is not clear what feature this switch controls.

The list of core skills now comes from Anthropic's server#

Claude Code now takes its list of core skills from a list sent by Anthropic's server, falling back to the last list it received

Unclear What the checks that empty the list look at is not settled.

Some built-in skills can now be hidden by an extra filter#

Claude Code gained another way to drop bundled skills, keeping only those on a kill switch's survivor list

Unclear It is not clear what condition triggers this filter or what the name check tests.

Skills sync reports more timing details#

Claude Code's skills sync diagnostics now record how long listing skills takes and, at startup, how long before the first message can go

Windows: Claude Code now looks at git's longpaths setting#

On Windows, Claude Code adds a new way to list folders and now includes git's longpaths setting among the git settings it checks

Unclear It is not clear what Claude Code does with the longpaths setting or the new folder-listing function.

On WSL, Claude Code now checks whether a path is on a Windows drive#

On WSL, Claude Code reads the system's mount list to tell whether a path sits on a Windows-side drive, and file checks compare link counts and file IDs

Unclear It is not clear what Claude Code does differently once it decides a path is on a Windows-side drive.

ALLUSERSPROFILE is allowed through, and the Opus 4 output limit table is gone#

ALLUSERSPROFILE joins a list of allowed Windows variables, and a table fixing Opus 4 and 4.1 output at 8192 tokens was replaced

Unclear What the variable list governs, and where the Opus 4 limits now come from, is not stated.

Which attachments become reminders to the model is now decided by their role#

Claude Code now uses each attachment's recorded role, not a fixed list, to decide which attachments become system reminders

Unclear It is not clear which attachment types are handled differently now, or what the accountMemoryWithheld option does.

Changed rule for which failed downloads are counted#

A failed download that was not a prefetch now always counts; a prefetch counts only if data arrived or it was too large

Unclear What this check feeds into, including whether a counted failure means the download is not retried, is not clear.

Access check results are remembered with a status#

Claude Code's saved result for one access check now stores a status, and a hit is logged as remembered instead of cached

Unclear It is not clear what statuses other than accessible can be stored.

Access check now reports an outdated result as accessible#

Claude Code's Mantle access check now records an "outdated" result as accessible in its usage data, not just an "accessible" one

Unclear It is not clear what the Mantle probe checks or whether anything besides reporting changes.