Function activation_test_mode_enabled 

fn activation_test_mode_enabled() -> bool

Test-mode gate. When the env var NIXFLEET_AGENT_ACTIVATION_TEST_MODE is set to ANY value, handle_intent short-circuits the activation pipeline and emits LocalActivationCompleted with the intent’s target as the observed value. Smoke tests (tests/runtime_smoke.rs) MUST set this — they exercise the runtime integration end-to-end through the durable queue, not the actual activation subprocess. Production code paths must NEVER set it; the gate is read on every intent so a test setup mistake fails closed (no activation) rather than open (real subprocess).