{"version":"2.1.236","anchor":"the-message-tool-s-notify-when-idle-parameter-and-its-suppor","canonical_anchor":"the-message-tool-s-notify-when-idle-parameter-and-its-suppor","heading":"The message tool's notify_when_idle parameter and its supporting layer","tier":"soon","area":"Cross-Session Messaging","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.236\/e\/the-message-tool-s-notify-when-idle-parameter-and-its-suppor","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.236","markdown":"### The message tool's `notify_when_idle` parameter and its supporting layer\n\nClaude can ask another session to ping it when idle, but the parameter is hidden unless the gate is on.\n\n**What**\n\nThe tool Claude uses to message another session on the same machine gained a `notify_when_idle` input that subscribes to a single notice when that session next goes idle or exits; sent without a message body it is a pure subscription. The parameter is only added to the tool schema when cross-session messaging is on, so with the gate off the model never sees it.\n\n**Details**\n\n- Gate: `CLAUDE_CODE_HARBOR_KITE` environment variable, otherwise `tengu_harbor_kite` (fallback false), plus `tengu_harbor_kite_win` (fallback false) on Windows. Absent server config, invisible.\n- Refusal reasons each get their own sentence: `no-inbox`, `self-target`, `peer-unsupported`, `unreachable-namespace`, `cap`, `peer-gone`.\n- Subscriptions live in a table with a maximum size, eviction and expiry.\n- Sub-agents and teammates are refused, recorded as `subscribe_refused_principal`, under `cross_session_notify_idle` telemetry.\n\n**Evidence**\n\n`Ask a session ON THIS MACHINE to send you ONE notice when it next goes idle`\n\n- Flag `tengu_harbor_kite`: Off by default, switched on for this account (read for one account on one subscription tier against v2.1.236; this account: on, anonymous baseline: on, compiled default: off)\n- Flag `tengu_harbor_kite_win`: Off in both readings (read for one account on one subscription tier against v2.1.236; this account: off, anonymous baseline: off, compiled default: off)\n- Area: Cross-Session Messaging\n- Names: `notify_when_idle`\n- Tier: Nothing to try yet\n- Useful: 2\/5\n- Signal: 4\/5\n- Present in the build but not switched on"}