As AI systems transition from isolated language models to autonomous and semi-autonomous agents, dominant failure modes shift from reasoning errors to orchestration failures. This study introduces the Blackboard Kernel (BK), a governed cognitive substrate that enforces typed internal state, evidence-based belief commitment, and constraint-gated action execution. In a controlled evaluation of 1,200 episodes, the deterministic BK agent achieves 100.0% task success with zero unsafe actions, and the LLM-backed BK agent achieves 99.0% task success with zero unsafe actions — while baseline architectures produce unsafe actions in 38.7–43.0% of episodes.