hostSessionId
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.
Session registration now reports a hostSessionId read from the CLAUDE_CODE_HOST_SESSION_ID environment variable
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.274.
In the changelogs
2Releases whose published page names hostSessionId.
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v2.1.274
hostSessionId now reported, reading CLAUDE_CODE_HOST_SESSION_ID
Session registration now reports a hostSessionId read from the CLAUDE_CODE_HOST_SESSION_ID environment variable
found in this entry's text
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v2.1.274
Session metadata gains hostSessionId and outsideOrgReader fields
Session metadata and permission info now include new hostSessionId and outsideOrgReader fields
named in this entry, found in this entry's text
First cited
1The earliest release whose published evidence quoted hostSessionId was v2.1.274, 16 Sep 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.
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.