Function local_channel_id 

pub fn local_channel_id() -> String

This process’s own channel id — AGENTMUX_CHANNEL, default "stable".

The single source of the channel string written into every shared registry entry (write_shared_from_env and siblings), and — as of SPEC_JEKT_CROSS_CHANNEL_TRUST_2026_09_02.md Phase B — the string injected into each agent’s MCP env as AGENTMUX_CHANNEL so the source_channel a sender binds into its cross-channel signature (§D5) is byte-identical to the channel a receiver finds on the entry it verifies against. Two independent reads of the env var would agree today; one function guarantees they keep agreeing.