{"name":"tengu_bg_prewarm_burst_concurrency","slug":"tengu-bg-prewarm-burst-concurrency","family":"flag","title":"Feature flags","noun":"feature flag","description":"Background session prewarm now checks the concurrency limit instead of the delay value.","description_source":"entry","described_by":{"version":"2.1.248","anchor":"prewarm-burst-guard-tested-the-wrong-value"},"presence":{"first_seen":"2.1.206","removed_in":null,"in_current_build":true,"newest_mined":"2.1.308","builds":91,"mined_builds":149,"first_cited":{"version":"2.1.248","released_at":"2026-08-27 20:35:36","spans":1}},"aliases":[],"entries":[{"version":"2.1.248","anchor":"prewarm-burst-guard-tested-the-wrong-value","heading":"Prewarm burst guard tested the wrong value","line":"Background session prewarm now checks the concurrency limit instead of the delay value.","released_at":"2026-08-27 20:35:36","reason":"gate cited by this entry, found in this entry's text"}],"entries_total":1,"docs":[],"docs_total":0,"gates":[{"version":"2.1.248","state":"unknown","account":null,"baseline":null,"code_default":null}],"related":[{"name":"tengu_bg_prewarm_burst_delay_ms","slug":"tengu-bg-prewarm-burst-delay-ms","description":"Default `15000` (milliseconds). How long the background-session supervisor waits, once it is ready, before its prewarm burst: restarting idle background sessions on a stale Claude Code version onto the running one, `tengu_bg_prewarm_burst_concurrency` (default `3`) at a time. The burst is skipped if the supervisor is shutting down, the concurrency is `0` or less, or `tengu_bg_attach_upgrade` is off."}],"url":"https:\/\/changelogs.core-directive.com\/reference\/flag\/tengu-bg-prewarm-burst-concurrency","family_url":"https:\/\/changelogs.core-directive.com\/reference\/flag.json"}