Claude Code v2.1.15 / Changelog

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4 entries

Changesopen

Cowork Plugins Directory Support [Hidden]#

What

A new hidden --cowork flag enables an alternate plugin directory for development and testing workflows.

Usage

# Via CLI flag
claude plugins list --cowork
claude plugins install my-plugin --cowork

# Via environment variable
CLAUDE_CODE_USE_COWORK_PLUGINS=true claude

Details

When enabled, plugins are stored in cowork_plugins/ instead of plugins/
Settings file changes to cowork_settings.json instead of settings.json
The --cowork flag is hidden from help output (.hideHelp())
Only available with user scope for certain commands; attempting to use with other scopes results in an error
Can be enabled via CLAUDE_CODE_USE_COWORK_PLUGINS environment variable

Evidence

Cn5() at line 90980 (plugin directory selector, contains "cowork_plugins"), CLI definitions at line 560985 (contains "--cowork", "Use cowork_plugins directory")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

API Billing Attribution Headers #

What

Claude Code now sends version and entrypoint information in API requests for better usage tracking and diagnostics.

Details

Header format: x-anthropic-billing-header: cc_version=2.1.15.{hash}; cc_entrypoint={entrypoint}
The entrypoint is read from CLAUDE_CODE_ENTRYPOINT environment variable (defaults to "unknown")
Previously this header was stubbed to always return an empty string (gated by tengu_ant_attribution_header_new flag)

Evidence

X61() at line 158274 (attribution header generator, contains "x-anthropic-billing-header")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

React Compiler Memoization #

What

The entire UI layer has been updated to use React Compiler's automatic memoization through useMemoCache.

Details

In v2.1.14: Only 1 reference to react.memo_cache_sentinel (the definition in React internals)
In v2.1.15: 736 usages across UI components
A new shared e() function wraps useMemoCache for use across all components
This provides automatic fine-grained memoization without manual useMemo/useCallback calls
Should improve rendering performance by avoiding unnecessary re-renders

Evidence

e = function(A) { return dn5.H.useMemoCache(A) } at line 92039, 736 occurrences of Symbol.for("react.memo_cache_sentinel") checks throughout UI code

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Remote Mode State Tracking #

What

Added internal state tracking for remote/teleport mode sessions.

Details

New isRemoteMode boolean state in the global state object
Getter Hf1() and setter Fg6() functions added
Used to modify behavior when running in remote session context (e.g., preventing empty input submission)

Evidence

k6.isRemoteMode = A at line 2350, usage checks at lines 548372 and 548402

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

1 entry

Notesopen

The --cowork flag and cowork plugins directory are hidden internal features, likely intended for Anthropic development and testing workflows. They are not documented in public help output and should be considered unsupported for general users.

Claude Code v2.1.15

Changesopen

Cowork Plugins Directory Support [Hidden]#

API Billing Attribution Headers#

React Compiler Memoization#

Remote Mode State Tracking#

Notesopen

#

Anthropic’s official release notes

API Billing Attribution Headers #

React Compiler Memoization #

Remote Mode State Tracking #