docs: Claude Code v2.1.216 - disable filesystem sandbox layer, hooks continueOnBlock, rewind symlink fix

[claude-yolo]

Night shift report

WHY THIS MATTERS: v2.1.216 ships one genuinely new sandboxing knob (sandbox.filesystem.disabled) that operators will want to evaluate — it lets you sandbox network access without filesystem restrictions, a meaningful posture shift for teams who trust their code but not their network calls. Two behavior changes (hooks deny semantics, rewind symlink handling) are silent breaking changes that could surprise existing setups: hooks that relied on PreToolUse deny feeding the reason back to Claude now end the turn instead, and /rewind now silently skips symlinked/hard-linked files rather than writing through them.

HIGHLIGHTS:

• New: sandbox.filesystem.disabled — set to true in user/managed/CLI settings to turn off filesystem isolation while keeping network isolation; lets subprocesses touch the full host filesystem while their network egress stays locked to allowedDomains. Requires v2.1.216. Project settings (.claude/settings.json) cannot set this — only user or managed settings can, preventing a checked-out repo from widening its own sandbox. Security note: with auto-allow on, a sandboxed command can now write shell startup files or executables, creating escalation risk; docs include a new Warning block.
• Breaking (hooks): PreToolUse deny behavior flipped — before v2.1.210, deny returned the reason to Claude as a tool error and the turn continued; now by default the turn ends and the reason appears as a chat warning. New continueOnBlock: true flag restores the old feed-back-to-Claude behavior. PostToolUse also gains continueOnBlock: true support.
• Breaking (rewind): /rewind now skips symlinked and hard-linked files with a "Restored the code, but skipped N files" warning instead of writing/deleting through links silently. Affects dotfile-manager symlinks and pnpm hard-links. Debug log (/debug before restore) names the skipped paths.
• Chrome auth change: Chrome integration now requires interactive /login auth; sessions using API keys or claude setup-token long-lived tokens no longer attempt to connect (previously they tried and failed with 403).
• Streaming improvement: Headless JSON-stream mode now waits up to 30 seconds for a slow consumer to drain queued output before exit (was ~2 seconds), preventing truncated large responses.
• New OTEL config: CLAUDE_CODE_OTEL_CONTENT_MAX_LENGTH configures the inline truncation limit for OTEL_LOG_TOOL_CONTENT=1 and OTEL_LOG_RAW_API_BODIES (was hardcoded at 60 KB). Requires v2.1.214+.
• CHANGELOG entry: Fable 5 usage-credits consent prompt now starts with the decline option focused (UX change, not a feature).
• Support articles, metadata: ~30 support articles refreshed (CDN image tokens, minor wording) — noise.

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