## Definition
**Memory scope promotion discipline** is the rule that a fact must reach stability before it is written to a memory layer with a slower decay rate. Promoting a session-level observation to project or user memory too early embeds a tentative state as canonical truth — a silent hallucination factory for future agents.
## The Decay-Tiered Write Rule
The three scopes in a [[Layered Memory Architecture]] carry implicit commitments:
| Scope | Decay rate | Write trigger |
| ------- | ---------- | ---------------------------------------------------------- |
| Session | Fast | Any working decision in the current turn |
| Project | Medium | Decision is shipped, tested, or explicitly ratified |
| User | Slow | Stable preference observed across multiple sessions |
The discipline: **only promote when the fact is stable at the destination layer's timescale.** A naming convention agreed in turn 3 may be reversed in turn 9 — let it live in session scope until it ships.
## Two Failure Modes to Avoid
1. **Premature promotion.** Writing a session decision to project memory before it is stable. Future agents read it as settled when it may have been superseded two turns later.
2. **Scope contamination.** Writing project facts into user memory. "User prefers PostgreSQL" is not a user preference; it is a project constraint. Misrouting it pollutes the user scope with data that expires when the project changes.
## Practical Signal for Promotion
The author's heuristic from Module 6: wait until the change *ships or is otherwise stable* before writing it to a layer with slow decay. Concrete triggers:
- **Session → Project**: a PR is merged, or the decision survives a full session review unchanged.
- **Project → User**: a working pattern is observed across multiple independent projects.
Until those triggers fire, keep the fact in the faster-decay scope — or don't write it at all.
## Relation to Auto-Memory
[[Auto-memory]] agents write on their own initiative; the promotion discipline is the human policy that governs *which scope* each write targets. Without it, auto-memory defaults to writing wherever is convenient, which tends to be project scope — and project scope stales faster than user scope allows.
## Related
- [[Layered Memory Architecture]]
- [[Auto-memory]]
- [[Context vs Memory]]
- [[Architecture Decision Record]]
## Sources
- [[Modern AI Software Engineering - The Orchestrators Playbook]]