AI Coding Tools Roundup: Claude Code 2.1.284 Makes Auto Mode the Default as Copilot Adds Sonnet 5.5
The biggest AI coding story today is a tooling one. Anthropic shipped Claude Code v2.1.284 on September 28, which starts interactive sessions in auto mode by default and makes Claude Sonnet 5.5 and Opus 5.5 the default models. On the same day, GitHub announced Claude Sonnet 5.5 in GitHub Copilot. Codex CLI and OpenCode had quieter days.
Claude Code 2.1.284: Auto Mode Becomes the Default
The most consequential change in the release notes (see the Claude Code changelog) is that interactive terminal and VS Code sessions now start in auto mode when no permission mode is configured, on every plan and provider. If you prefer the old behavior, permissions.defaultMode still overrides it. Teams that rely on the previous default should set it explicitly rather than assume.
Auto mode also got a finer permission control: a new "Yes, but ask again next time" answer for reads outside the working directories lets you allow a single read without opting into all later ones.
New Default Models: Sonnet 5.5 and Opus 5.5
Version 2.1.284 adds claude-sonnet-5-5 as the default Sonnet model on the Anthropic API, with a 1M context window and pricing of $2/$10 per million tokens and $0.20 per million for cache reads. claude-opus-5-5 becomes the default Opus model, also with 1M context, at $4/$20 per million tokens. For the API-level details, see our earlier Claude Sonnet 5.5 developer guide and Anthropic's news page.
Other Notable Claude Code Additions
- Spend visibility: dollar amounts now appear in /usage and the status line spend limit (for example "$271.40 / $500.00 spent this month") when the Claude apps gateway runs this version or later.
- MCP recovery: /mcp reconnect all retries every failed or unauthenticated MCP server at once, and resumed sessions now wait up to 10 seconds for a connecting server instead of failing with "No such tool available".
- Effort controls: the /effort slider keys are rebindable, and Ultracode is now its own toggle that no longer forces xhigh effort.
- Enterprise gateway: Google Cloud OTLP telemetry export, certificate-based (private_key_jwt) authentication to identity providers, and higher request-header limits for users in many groups.
Reliability and Security Fixes Worth Noting
- "Prompt is too long" errors that persisted after compaction now trigger a second, more aggressive compaction.
- Damaged response streams and overload errors after a thinking block are retried instead of surfacing raw errors like "undefined is not an object".
- Under managed settings, plugins can no longer pre-approve their own tools via allowed-tools unless they come from an official Anthropic source or one your managed settings vouch for.
- The ANTHROPIC_FOUNDRY_RESOURCE value is now validated, and invisible characters or markup-imitating tags are neutralized in MEMORY.md and recalled memory notes before reaching the model.
GitHub Copilot: Claude Sonnet 5.5 Is Rolling Out
According to the GitHub changelog, Sonnet 5.5 is generally available in VS Code, Visual Studio, GitHub.com, JetBrains IDEs, Xcode, Eclipse, Copilot CLI and mobile, for Copilot Pro, Pro+, Max, Business and Enterprise users through the model picker. Rollout is gradual, so it may not appear immediately. GitHub says its testing showed Sonnet 5.5 matching Sonnet 5 on coding tasks while using significantly fewer steps, tokens and tool calls, and finishing faster. It targets well-scoped everyday work such as building features and fixing bugs. Billing is usage-based at provider list pricing.
For Business and Enterprise admins, new models default to enabled unless the global default or that specific model is disabled in the Copilot model policy, so check your settings if you restrict model access. More Copilot news is tracked in the Copilot changelog.
Codex CLI and OpenCode: Quiet Day
OpenAI's Codex releases page shows only 0.160.0 alpha builds since yesterday's stable 0.158.0, and OpenCode remains on v1.18.33 from September 28. Neither has a new stable release to report.
What It Means for Developers
- Set permissions.defaultMode explicitly in shared project settings before your team updates Claude Code, so nobody is surprised by auto mode.
- If you pin models with managed settings, review availableModels, since the new defaults change which models start by default.
- Copilot admins should decide whether Sonnet 5.5 should be enabled for their organization, because it defaults to on.
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