Kit branches a generic ACP subagent only when the agent advertises the ACP session/fork capability. If that capability is absent, fork returns an unsupported error; only the exact acp.kit harness receives Kit's private transcript-cloning fallback.
This leaves otherwise reusable ACP harnesses without a branching path. A generic fallback would need a safe, interoperable snapshot mechanism rather than assuming that a completed prompt can be replayed without changing behavior.
Relevant implementation: src/tools/subagent.rs (Subagents::fork) and src/acp_child.rs (ChildSession::supports_native_fork).
Kit branches a generic ACP subagent only when the agent advertises the ACP
session/forkcapability. If that capability is absent,forkreturns an unsupported error; only the exactacp.kitharness receives Kit's private transcript-cloning fallback.This leaves otherwise reusable ACP harnesses without a branching path. A generic fallback would need a safe, interoperable snapshot mechanism rather than assuming that a completed prompt can be replayed without changing behavior.
Relevant implementation:
src/tools/subagent.rs(Subagents::fork) andsrc/acp_child.rs(ChildSession::supports_native_fork).