Instance Identity in Persistent World Systems
Most interactive systems present a world without maintaining one.
A session begins. Content is generated, retrieved, or rendered. The session ends. The world — if there was one — does not persist. The next session begins from the same initial conditions.
This is the default case. Its prevalence makes it easy to overlook as a design decision. It is not neutral. It encodes a specific ontological commitment: that the system has no persistent identity between interactions. What appears to be a continuing world is a surface pattern re-instantiated on demand.
The concept of Instance addresses this directly.
A Formal Definition
An Instance is a specific running manifestation of a World, distinguished by three structural properties.
Unique identity. An Instance is individuated — it can be distinguished from other Instances of the same World, and from the World definition itself. Identity persists across time: the Instance at Round 40 is the same Instance as at Round 1, not a successor.
Accumulated state. An Instance maintains a state that changes in only one direction: forward. Each action applied to the Instance modifies its state. That state is the product of all prior actions in their causal sequence. The state is never rewound. The Instance at any given moment contains its entire history encoded in its current configuration.
Session independence. Sessions connect to an Instance; they do not constitute it. An Instance continues to exist between sessions. Its state at the beginning of a new session is identical to its state at the end of the previous one. The Instance does not reset when a session ends.
Instance vs Session
A session is time-bounded: it begins when a connection is established and ends when that connection is closed. Sessions are the unit of interaction.
An Instance is time-continuous: it persists regardless of whether a session is active. The Instance is the unit of identity.
The confusion between the two produces a specific misclassification: treating an Instance as though it were session-scoped. Under this model, users expect each connection to begin from initial conditions. When the system instead begins from the Instance's accumulated state, the behavior reads as unexpected rather than as a structural property.
Session-scoped systems have no memory of previous sessions because they have no persistent identity across sessions. Instance-bearing systems carry prior sessions in their state because sessions are episodes within a single continuing identity, not independent invocations.
Instance vs World
A World is a definition: the rules, entities, causal structure, and possibility space that govern a simulation. The World specifies what kinds of events can occur, what kinds of entities exist, and how state evolves in response to actions.
An Instance is a specific trajectory through that possibility space. Where a World defines what can happen, an Instance records what has happened — in a specific sequence, producing a specific accumulated state.
The relationship parallels the distinction between a class definition and a running process: the class specifies structure; the instance is a specific execution with its own accumulated history. Multiple Instances can run from a single World definition while diverging entirely in their states.
This distinction determines what a reset actually affects.
Instance vs Save State
A save state is a snapshot of an Instance's state at a specific moment, preserved for restoration purposes. The semantics are backward-directed: the save state exists to support returning the Instance to a prior configuration.
An Instance's running state is forward-directed. It maintains only the current state, which encodes the causal history of everything that produced it. There is no mechanism for returning to a prior state — only continuing from the present one.
Save states introduce reversibility into systems. Instances, structurally, are irreversible. A system that can be restored to a prior state has not maintained persistent identity — it has maintained persistent availability of prior states. The distinction is significant: one is a temporal structure; the other is a restoration mechanism imposed on top of one.
Reset Semantics: Instance and World
Resetting an Instance does not reset the World.
A reset terminates the current Instance's causal chain and initializes a new Instance from zero. The new Instance begins with no accumulated state. The World definition remains unchanged — the same rules, entities, and possibility space that governed the original Instance now govern the replacement.
This is not reversal. The original Instance's history is not undone. A new process begins from initial conditions within the same World. The result is a new trajectory, not a corrected prior one.
Conflating Instance reset with World reset produces a specific error: treating the reset as removal of something from the World. What is removed is the Instance — a specific running process. The World persists independently of any Instance running within it.
Causality and Continuity
The Instance is the unit of causal continuity in persistent world systems.
Causal continuity means that the state at any moment is a function of the state at the immediately prior moment plus the action applied to it. No state is generated independently. Each state is causally downstream of all prior states.
This chain is the Instance's identity across time. What makes Round 40 "the same Instance" as Round 1 is not an unchanging substrate — the state has changed substantially. It is the unbroken causal chain connecting each state to the next that constitutes identity. Remove the chain and you do not have an older version of the same Instance; you have a different system.
A system without Instance identity cannot maintain causal continuity across sessions. Each session begins from initial conditions, and the causal chain starts fresh. Whatever occurs in one session has no structural effect on the next.
Cognitive Implications of Instance Absence
Systems without persistent Instance identity produce a characteristic interaction pattern: users accumulate no meaningful model of system state between sessions.
In a session-scoped system, there is nothing to return to. A new session is not a continuation — it is a new invocation. The user's knowledge of prior system state becomes structurally irrelevant between sessions, because that state does not persist into the next invocation.
This forecloses a class of cognitive engagement that Instance-bearing systems support: orientation within an ongoing state. In a persistent system, the question "where does this world currently stand?" has a determinate answer independent of whether any user is present. The question presupposes that the world has a state that persists between observations — which presupposes an Instance.
The absence of Instance identity is not a feature deficit. It is an ontological commitment: the system is not a continuing subject. It is a process that begins when invoked.
The Instance is what makes the world real between observations.
For a structural analysis of what distinguishes persistent worlds from game systems at the organizational level, see Persistent World ≠ Game. For the causal mechanics underlying state accumulation, see Game Mechanics vs State Dynamics.
