Every documented AI agent-memory reorganization trigger fires on an accumulated threshold, not a session boundary

Four independently-designed agent-memory systems converge on the same trigger shape: a running quantity crosses a threshold, not a session or actor boundary.

• Generative Agents (Park et al. 2023, arXiv:2304.03442) fire their reflection-synthesis step on accumulated importance: "we generate reflections when the sum of the importance scores for the latest events perceived by the agents exceeds a threshold (150 in our implementation)."
• MemGPT (Packer et al. 2023, arXiv:2310.08560) evicts on context-window occupancy: the queue manager warns "when the prompt tokens exceed the 'warning token count' of the underlying LLM's context window (e.g. 70% of the context window)" and flushes at "the 'flush token count' (e.g. 100% of the context window)."
• LangChain langmem (langchain-ai.github.io/langmem/guides/summarization/) summarizes on a token budget: "If the messages in state["messages"] fit into max_tokens_before_summary budget, we will simply return those messages. Otherwise, we will summarize."
• Anthropic compaction (platform.claude.com/docs/en/build-with-claude/compaction) is configured on a token count: "Claude automatically summarizes your conversation when it reaches the configured token threshold," where the "value must be at least 50,000 tokens."

Even the field's closest whole-store analogue, Anthropic's Dreams, has no automatic trigger documented — every path is a developer-issued dreams.create(...) call — and the only recommended cue is again capacity: "When a store reaches its 2,000-memory limit, writes to new memories fail," so run "a dreaming session... before the store fills up." No documented mechanism ties reorganization to session count, session boundaries, or a change of model/agent.

This is direct evidence from the vault's own peer field that current practice does not treat session onset as a reorganization trigger — it does not rule out onset as an untried better trigger, only establish it is not the converged answer. It bears on question-new-session-onset-as-rewiring-trigger (evidence against the free-lunch reading) and on question-consolidation-pass-vs-revisit-protocol — the accumulated-vs- targeted framing is the same choice the vault faces. Cost corollary: claim-localized-memory-maintenance-cost-advantage. moc-schema-change-and-restructuring.