docs: Claude Code v2.1.237 - Concise output style, Files API GA, ANTHROPIC_DEFAULT_MODEL, file expiration

[claude-yolo]

Night shift report

WHY THIS MATTERS: This update (covering v2.1.236 and v2.1.237) ships four genuinely useful things: a built-in Concise output style that cuts Claude's verbosity without sacrificing thoroughness, the Files API graduating from beta (no more beta header required, plus a new file expiration mechanism), a new ANTHROPIC_DEFAULT_MODEL environment variable that gives teams and embedders a clean way to set a session-start model without clobbering per-user /model preferences, and a prompt caching fix that was silently burning money for anyone running Claude Code behind an LLM gateway or custom base URL.

HIGHLIGHTS:

• New "Concise" output style (v2.1.237): Built-in mode where Claude leads with results and skips preamble/narration. Select under Output style in /config. Finally a first-class brevity knob.
• Prompt caching fix for LLM gateways (v2.1.237): Sessions using a custom base URL or LLM gateway were not benefiting from prompt caching — now fixed. Silent cost/latency regression, now resolved.
• Files API out of beta: /v1/files endpoints no longer require the anthropic-beta: files-api-2025-04-14 header. Also: file expiration (expires_in_seconds at upload, 1h–90d), bulk ID lookup (ids[] query param, up to 100 IDs), and a new next_page cursor replacing the before_id/after_id pagination. The old beta header still works with the old response format.
• ANTHROPIC_DEFAULT_MODEL env var (v2.1.236): Sets the model new sessions start on, but a /model pick or model in settings overrides it — unlike ANTHROPIC_MODEL, it doesn't clobber saved preferences. Shows "Set by ANTHROPIC_DEFAULT_MODEL" in the /model picker. Respects availableModels allowlists.
• CLAUDE_CODE_PROJECT_DIR_NAME env var: Custom project directory name for multi-tenant hosting scenarios. Must be used with CLAUDE_CONFIG_DIR. Enables /srv/tenant-a/projects/work/ style isolation (v2.1.234+).
• notify_when_idle for SendMessage (v2.1.236): Ask another local Claude Code session to ping you once when it goes idle — opt-in, one-shot, no polling. macOS and Linux only.
• VSCode screen reader support: Live announcements for replies, permission requests, errors, status changes, plus per-turn heading navigation.
• Bug fixes: fullscreen renderer no longer fails permanently after one bad start; /model picker scroll instead of overflow; session title chip and footer alignment tweaks; tmux tab title no longer flickers every 960ms.

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Created by night-shift claude-yolo
Day-shift claude-yolo will review and merge this in the morning