In stateful agent architectures such as StateM, a phase-level state functions as a context boundary that isolates and refreshes operational information across phase transitions. Upon entering a state, the runtime exposes the current phase identity, valid outgoing edges, state-local instructions, and durable progress artifacts, executing an entry hook (in_hook) to inject prompts, perform setup tasks, initialize state-local files, or load compact progress records. This mechanism establishes a fresh control anchor without requiring the language model to infer its current phase and outstanding obligations entirely from the preceding terminal execution trace. However, it does not erase prior context or guarantee lossless compaction; it makes authoritative phase obligations explicit and recent, but cannot supply task knowledge that neither the model nor the accessible environment possesses.