Function backend_test_url 

pub fn backend_test_url() -> String

Local backend URL for client tests.

Each worktree publishes the stack on its own ports, so the address comes from the environment. dev/worktree-env writes it and the just recipes export it. The constant above is the fallback for a bare cargo test.

Native reads the variable at run time. Wasm has no std::env, so the value is baked in at build time instead; build through just wasm test so the worktree’s environment is loaded.