The Mutation Timeline

Mutability × Time: The Compound Risk – Part 2/4

 

Every mutable instance follows a predictable arc of decay. It begins life pristine—freshly instantiated with clean state and clear purpose. But from that moment forward, each interaction leaves a mark, each modification accumulates risk, and each passing moment expands the surface area for unexpected behavior.

The timeline unfolds in stages. Birth brings the instance into existence with its initial state. Initialization sets up the foundational data, often still predictable and controlled. Critically, the gap between birth and initialization creates a vulnerability window—the instance exists but isn't fully functional, creating opportunities for misuse or partial operation. Then comes Drift—the gradual accumulation of state changes that weren't part of the original design contract. What follows is Contamination, where unrelated concerns begin bleeding into the instance's responsibilities, creating hidden dependencies. Finally, Corruption arrives when the instance's actual behavior diverges so far from its intended purpose that it becomes actively harmful.

Each stage compounds the problems of the previous one. A small drift in state becomes the foundation for contamination. Contamination creates the conditions for corruption. The debugging difficulty doesn't just increase linearly—it explodes exponentially because each new problem interacts with all the accumulated baggage from before. You're not just fixing the current issue; you're untangling a web of historical decisions that may no longer make sense or may not even be documented.

This creates what we might call the "state archaeology problem." When an instance misbehaves, the critical question becomes: how did it get into this state? But mutable instances don't keep journals. The path from pristine birth to current corruption is often irretrievable, lost in the mists of countless method calls, property updates, and side effects that seemed harmless at the time.

Our agent status manager exemplified this timeline perfectly. Born clean in the dependency factory, it lived in limbo until the orchestrator finally provided an agent ID—a dangerous gap where the instance existed but couldn't fulfill its purpose. It drifted when developers started reusing it across workflows, became contaminated when multiple agent IDs started competing for attention, and finally corrupted when state from one workflow began polluting another's execution.

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Previous: Part 1 – The Lifespan Paradox
Next: Part 3 – Invisible Coupling