system
A Claude Code settings key, read out of the shipped bundle. No mined inventory carries it: everything below comes from what this site has written about it.
SDK callers get an mcp_server_errors array naming rejected MCP configs, so CI can fail on it.
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.219.
In the changelogs
25Releases whose published page names system.
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v2.1.321
Notification messages no longer appear in stream-json output
System messages with subtype
ui_notifyorui_notify_cancelare now left out of Claude Code's stream-json outputfound in this entry's text
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v2.1.317
Programs built on Claude Code can mark a typed "ultrathink" to raise effort
SDK hosts can send
ultrathink_typedto say a person typed "ultrathink", so the turn runs at xhigh effort when the session allows itfound in this entry's text
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v2.1.309
Startup fails clearly when the system certificate store is empty
With CLAUDE_CODE_CERT_STORE=system, an empty or unreadable system store now stops startup instead of quietly using bundled certificates
found in this entry's text
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v2.1.307
Programs driving Claude Code can ask for an interrupted prompt to be requeued
A new internal option asks Claude Code to put a prompt back in its queue if an interrupt arrives just as the prompt is being picked up
found in this entry's text
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v2.1.282
SDK hosts can receive a session's list of published artifacts
A new internal
session_metadatamessage carries a session's artifact list so apps built on the SDK can keep a session summaryfound in this entry's text
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v2.1.281
SDK system event per_turn_effort_changed
A new internal SDK message reports when a conversation stops sending effort on every turn
found in this entry's text
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v2.1.281
SDK Remote Control: failures carry a failure_kind, and control errors gain an error_code
SDK Remote Control failures now report a
failure_kind, and failed enable requests return anerror_codesuch asremote_control_policy_disabledfound in this entry's text
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v2.1.280
Teammate name reservation expanded to include 'user' and 'system'
Teammate names "user" and "system" are now reserved alongside "main" and "team-lead"
named in this entry
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v2.1.280
Transcript repair now also fixes malformed 'system' rows, including stop-hook summaries
Transcript repair now also fixes corrupted 'system' rows, including stop-hook summary rows, and reports counts via telemetry
found in this entry's text
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v2.1.280
New detection for misordered 'system' role messages in API errors
Claude Code now recognizes API errors about misplaced 'system' role messages and pinpoints the offending message
found in this entry's text
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v2.1.277
New prompt-source classification for message origin telemetry
Internal telemetry now classifies where each message came from into one of nine categories
found in this entry's text
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v2.1.271
rapidFollowupPreempt SDK capability, gated behind tengu_zippy_spindle (default off)
New SDK capability lets a consumer ask Claude Code to auto-stop a turn when a rapid follow-up message arrives
found in this entry's text
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v2.1.271
New system event: turn_preempted for rapid follow-up messages, gated behind a rollout flag and client opt-in
A new turn_preempted event fires when Claude Code cancels a turn because you sent a follow-up message before it produced output
found in this entry's text
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v2.1.269
'Tether' thread-continuation requests can omit system prompt/tools when continuing, behind two off-by-default flags, with a fingerprint-mismatch circuit breaker
Continuing a server-side conversation thread can now skip resending the system prompt and tools list, with a fallback if the server disagrees
found in this entry's text
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v2.1.269
Model-parameter allowlist changed from array to Set
Internal list of allowed API request fields switched from an array to a Set
found in this entry's text
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v2.1.257
Mid-conversation tool-change surfacing to the model, gated off by default
Tools added or removed mid-conversation can be surfaced to the model, but the beta capability is gated off by default.
found in this entry's text
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v2.1.246
Local file reads route through the storage backend when it serves the space
Settings and marketplace files are read once through the storage layer instead of twice.
found in this entry's text
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v2.1.246
Storage backend gains two host-supplied options with no caller
Storage can accept a host-supplied config path and per-space service declarations, but nothing passes them.
found in this entry's text
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v2.1.242
A headless client for cloud sessions appears in the bundle
A full headless client for driving cloud sessions over stream-json is in the bundle.
found in this entry's text
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v2.1.229
Slash commands can mark themselves terminal-only, and SDK clients get the list
Terminal-only commands like /doctor and /exit are flagged so non-terminal hosts can hide them.
found in this entry's text
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v2.1.219
SDK init message reports skipped MCP server configs
SDK callers get an mcp_server_errors array naming rejected MCP configs, so CI can fail on it.
found in this entry's text
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v2.1.213
SDK Protocol: Plugin Version Field
found in this entry's text
- v2.1.204
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v2.1.196
awk Command Security Analysis
found in this entry's text
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v2.1.101
CLAUDE_CODE_CERT_STORE Environment Variable
found in this entry's text
First cited
0No release's published evidence quotes this name. The ledger indexes the Evidence lines of every changelog on this site, so this says nobody here has ever quoted it; it says nothing about how old the name is.
Presence across releases
0The miner has never read a build containing this name. It is here because a changelog entry of ours names it, which is evidence that it existed and not evidence of which releases carried it. The inventory starts at v2.1.138 and everything older than that was never mined.
Read out of the published npm bundle release by release, and out of Anthropic's own documentation as this site captured it. Nothing on this page is a description anybody here wrote about what the settings key does. All settings keys.