agentId
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.
TaskOutput ignores the old wait_up_to setting and just uses the 30 second default timeout.
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.221.
In the changelogs
25Releases whose published page names agentId.
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v2.1.301
Sessions without local disk storage drop transcript entries instead of writing them
In sessions with no local disk, transcript entries with nowhere to go are now dropped with an error, and metadata folders are no longer created
found in this entry's text
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v2.1.280
Plugin/SDK host API: new
$.session.sendoperationPlugins and SDK integrations gain a session.send call to message a target by name, agent id, or session/agent address
found in this entry's text
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v2.1.280
Plugin
$.session.messagesand$.session.usagenow accept an agentId/as parameterPlugin session.messages and session.send can now target a specific agent via an agentId/as parameter
found in this entry's text, named in this entry
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v2.1.280
SDK tool-result streaming can attach agentId/durationMs for Task-like tools
Streamed tool results for the Task tool can now include an agent ID and duration
found in this entry's text, named in this entry
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v2.1.280
Task delegation now carries usage stats forward
Sub-task handoff now carries forward token, tool-use, and duration stats
found in this entry's text
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v2.1.277
A tool-input schema case (C4) was removed from a validator
A tool-input validation case for task_id/agentId/bash_id fields was removed from a validator
found in this entry's text
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v2.1.275
Coordinator Bash safety restriction exists but is compiled off
A safety check that would block risky Bash calls from a coordinator agent exists in the code but is turned off
found in this entry's text
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v2.1.273
Tool-execution hook context object substantially reworked
The context object passed to tool-execution hooks was substantially reworked with many new fields
found in this entry's text
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v2.1.271
Hooks execution now tracks a live per-host list of running hooks
Claude Code now tracks a live list of running hooks per host, with an agent ID threaded through
found in this entry's text
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v2.1.271
turn.step plugin hook events now carry an agentId
The turn.step hook event now includes an agentId field
found in this entry's text
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v2.1.271
Server tool-use turn metadata now includes agentId
Server-side tool-use tracking now records which agent made the call
found in this entry's text
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v2.1.269
$.agent.spawn SDK call now returns an agentId on success
The agent.spawn plugin action now returns the new agent's ID on success
found in this entry's text
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v2.1.267
Tool-call context now threads an agentId into the managed-pass invocation
Tool-call context now passes through the id of the agent that invoked it
found in this entry's text
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v2.1.257
Spinner/stall telemetry now resets per agent
Spinner stall detection now resets when the active agent changes instead of carrying state across agents.
found in this entry's text
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v2.1.257
ToolSearchTool now scopes MCP tool filtering by agent/session betas
ToolSearch now filters the tool pool per agent and session betas before running its search.
found in this entry's text
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v2.1.242
Session journal keys are checked for consistency
A key naming a session's own journal is rejected if it also carries agent or run details.
found in this entry's text
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v2.1.225
Task-notification wake routing runs on a timer
Background task notifications get checked on a repeating timer and delivered per agent without duplicates.
found in this entry's text
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v2.1.221
TaskOutput no longer honours the legacy wait_up_to parameter
TaskOutput ignores the old wait_up_to setting and just uses the 30 second default timeout.
found in this entry's text
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v2.1.221
Auto mode exit message is tailored, and subagents no longer get it
The auto mode exit notice now matches how you configured it, and subagents no longer see it.
found in this entry's text
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v2.1.217
tengu_moth_copse— Voice/MCP URL Elicitation Toggle [Feature-Flagged]found in this entry's text
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v2.1.206
EndConversation Tool [Feature-Flagged]
found in this entry's text
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v2.1.198
Agent Spawn Results: Internal Metadata Privacy
found in this entry's text
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v2.1.179
Spinner State Is Now Per-Agent
found in this entry's text
- v2.1.21
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v2.0.28
Agent Result Tracking
found in this entry's text
First cited
20The earliest release whose published evidence quoted agentId was v2.1.179, 16 Jun 2026. That is the oldest release this project wrote about it, so it is a floor on the name's age and not the release that introduced it. It is not a presence reading: which builds carried the name is the table below.
14 further spans in the ledger name it. The list above is the earliest first and stops at 6.
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.