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DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

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Claude Code v2.0.77

14 entries read diff v2.0.76 → v2.0.77 Markdown

This release focuses on internal performance improvements with new slow operation detection and diagnostics, enhanced OAuth authentication recovery, better enterprise MCP policy enforcement, and updated max token handling for Claude Sonnet 4 with the 1M context beta. Several large dependency libraries (AJV JSON Schema validator, terminal setup helpers) were removed and replaced with more efficient alternatives.

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9 entries

Changesopen

EPIPE Error Handling for Piped Output#

What

Claude Code now gracefully handles broken pipe (EPIPE) errors when output is piped to another process that closes early.

Usage
claude -p "list files" | head -1  # No longer crashes if head closes early
Details
  • Prevents crashes when Claude Code's output is piped to a process that terminates before reading all output
  • Automatically destroys stdout/stderr streams on EPIPE instead of throwing an uncaught error
  • Improves CLI scripting reliability
Evidence

HS0() at line 519 (EPIPE handler, contains "EPIPE")

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

Enterprise MCP Exclusive Mode#

What

Enterprises can now configure MCP servers in exclusive mode, preventing users from adding custom MCP servers.

Usage: Configured via enterprise policy. When active, users see:

Cannot add MCP server: enterprise MCP configuration is active and has exclusive control over MCP servers
Details
  • Allows enterprises to lock down MCP server configuration
  • Users cannot add MCP servers via /mcp command or config files when active
  • Provides clear error messaging about why server addition is blocked
Evidence

jd() at line 398745 (MCP server add function, contains "enterprise MCP configuration is active and has exclusive control over MCP servers")

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

Custom Betas Validation for API Users#

What

API key users can now specify custom beta headers, with validation against an allowlist.

Details
  • Only the context-1m-2025-08-07 beta is currently allowed
  • Warnings are shown for disallowed beta headers
  • OAuth users cannot use custom betas (server-controlled)
Evidence

JrQ() at line 140738 (beta validation, contains "Custom betas are only available for API key users")

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

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

Slow Operation Detection and Diagnostics#

Performance monitoring has been added for operations that may cause UI lag or delays:

  • JSON.stringify, JSON.parse, and structuredClone operations now log warnings when they take >200ms
  • fs.writeFileSync operations include size information in slow operation warnings
  • execSync shell commands are monitored for slow execution
  • All slow operations are reported via telemetry for aggregate analysis
Evidence

duA() at line 3224 (slow operation wrapper, contains "[SLOW OPERATION DETECTED]")

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

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

OAuth 401 Error Recovery#

What

OAuth authentication now attempts to recover from 401 errors by re-reading credentials from the system keychain.

Details
  • When a 401 error occurs, Claude Code checks if the keychain has newer credentials
  • If different credentials are found, they're used without requiring re-authentication
  • Reduces unnecessary login prompts when tokens are refreshed externally
  • Telemetry event: tengu_oauth_401_recovered_from_keychain
Evidence

C1B() at line 146443 (OAuth recovery, contains "tengu_oauth_401_recovered_from_keychain")

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

Claude Sonnet 4 with 1M Context Beta Support#

What

The max tokens calculation now correctly handles Claude Sonnet 4 models using the 1M context beta.

Details
  • Previously only models with [1m] in the name got 1M max tokens
  • Now also applies when context-1m-2025-08-07 beta header is used with claude-sonnet-4 models
  • Enables proper token limits for Sonnet 4 + 1M context combinations
Evidence

R$() at line 1818 (max tokens calculation, contains "claude-sonnet-4" and T8A)

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

Filesystem Operations Logging Improvements#

What

All filesystem operations now include descriptive context in debug logs.

Details
  • Operations like readFileSync, writeFileSync, symlinkSync now log with path information
  • Improved format: readFileSync(/path/to/file) instead of just readFileSync
  • Helps diagnose file-related issues in debug mode
Evidence

CQ variable at line 2388 (filesystem wrapper, contains descriptive operation strings)

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

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

Plugin Hooks Cleanup#

What

Added function to cleanly remove plugin-sourced hooks while preserving non-plugin hooks.

Details
  • sy0() function filters out hooks that have a pluginRoot property
  • Enables proper plugin unloading without affecting built-in hooks
  • Improves plugin lifecycle management
Evidence

sy0() at line 2270 (plugin hooks cleanup, filters by "pluginRoot")

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

Configurable Timeout Validator#

What

New timeout configuration validator with sensible defaults and caps.

Details
  • Default: 30000ms (30 seconds)
  • Maximum: 150000ms (2.5 minutes)
  • Invalid values fall back to default with a warning
  • Values exceeding maximum are capped with a notice
Evidence

sx0() at line 1741 (timeout validator, contains "Invalid value", "Capped from")

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

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

1 entry

Bug Fixesopen

#

  • Fixed potential crash when OAuth tokens expire and keychain has updated credentials (C1B() at line 146443)
  • Improved handling of model region prefixes (us, eu, apac, global) for Bedrock deployments (Ad1() at line 139167, MoQ() at line 139171)
4 entries

Internal Changesopen

#

The following changes are internal and don't affect user-facing functionality:

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

Removed Libraries/Code#

  • AJV JSON Schema Validator: The large AJV library (~5000+ lines) has been removed. Schema validation now uses a different approach (likely Zod which was already present)
  • Terminal Setup Helpers: Functions for configuring iTerm2, WezTerm, Ghostty, and Kitty Shift+Enter bindings have been removed from the diff (the /terminal-setup command still exists but implementation may have changed)
  • Keychain Delete Sync: The synchronous UsQ() keychain delete function was replaced with an async version J1B()

Added Libraries#

  • YAML Parser: A full YAML parsing library has been bundled (likely for reading .yml/.yaml config files)

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

Refactoring#

  • Zod schema validation error messages now use .issues instead of .errors property
  • Cache invalidation function fl() added for OAuth credential cache
  • Various dependency updates (google-auth-library version string changes)
Verbatim
No official entry

Not individually listed upstream

v2.0.77 does not have its own entry in Anthropic’s official changelog, because prerelease builds are often folded into a neighbouring release. Browse the full changelog for the closest official notes. Everything else on this page came out of the bundle instead, which is why the two lists don't match.

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