Custody Survivability Definition

Defining Custody Survivability for Assessment

This memo is published by CustodyStress, an independent Bitcoin custody stress test that produces reference documents for individuals, families, and professionals.

How Survivability Language Gets Misread

The term "survivability" carries intuitive weight when encountered without prior exposure to the assessment model. It suggests resilience, durability, or positive outcome. These connotations precede any formal definition and shape how results are interpreted before the reader understands what was actually measured.

The memo applies before any specific survivability result is interpreted or relied upon. It exists to constrain meaning at the point of first contact, preventing semantic drift that accumulates when terms are read through everyday associations rather than defined boundaries.

Custody survivability, as used in this assessment, refers to modeled system behavior under explicitly stated stress assumptions. It describes how a custody arrangement behaves when subjected to a defined scenario—such as the owner's death, incapacity, or prolonged absence—based on the information provided at the time of assessment. The term does not extend beyond that bounded observation.

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How Survivability Language Gets Misread

Survivability is frequently interpreted as a positive judgment about the system when encountered without definitional context. The word itself carries evaluative overtones. A system described as "survivable" sounds like a system that has been approved, validated, or certified. Readers unfamiliar with the assessment model infer that survivability is a favorable designation, a mark of quality that distinguishes adequate systems from inadequate ones.

An executor encounters a document stating that custody "survives under the modeled scenario." The executor reads this as confirmation that the system is sound. The phrase feels like a verdict. The executor proceeds with confidence that the assessment has blessed the arrangement, not recognizing that the statement describes behavior under one specific set of assumptions rather than general fitness.

Survivability is often read as evidence of safety, soundness, or correctness. These concepts are related but distinct. Safety implies protection against harm. Soundness implies structural integrity. Correctness implies alignment with norms or standards. Survivability, as modeled, implies none of these. It describes whether recovery is viable under stated conditions. A system can be survivable under one scenario while being unsafe, unsound, or misaligned with the reader's expectations in other respects.

Survivability outcomes are commonly mistaken for guarantees of future access. The word "survives" suggests continuation. A system that survives appears to persist, to endure, to remain accessible. Readers project this forward, treating a survivability finding as assurance that access will be available when needed. The finding does not provide this assurance. It describes modeled behavior at a point in time, not predicted behavior across all future conditions.

A beneficiary reads that the custody system "survives" a death scenario. The beneficiary interprets this as a promise: when the time comes, access will be possible. Years pass. Circumstances change. The system configuration drifts. When the scenario actually occurs, the conditions no longer match those that were modeled. The survivability finding described a past state, not a durable property.

Survivability language is assumed to generalize beyond the modeled scenario. The assessment models specific stress conditions with specific assumptions about timing, availability, authority, and human behavior. Readers often assume that a positive finding under one scenario implies resilience under adjacent scenarios. A system that survives death may not survive incapacity. A system that survives orderly transition may not survive contested succession. The scenario boundary is invisible to readers who encounter only the outcome.

Survivability results are treated as durable properties rather than time-bound observations. The assessment captures system behavior at the moment of evaluation. Wallets, keys, documentation, and dependencies exist in a particular configuration. That configuration changes over time as devices are replaced, services are discontinued, passwords are forgotten, and relationships evolve. A survivability finding does not update itself. It describes a snapshot that may no longer reflect current reality.

Survivability is conflated with preparedness, planning quality, or technical sophistication. A system that survives a modeled scenario is not necessarily well-prepared, well-planned, or technically sophisticated. It may survive due to simplicity, luck, or favorable assumptions. Conversely, a system that does not survive under the model may be sophisticated and well-intentioned but exposed to a dependency the scenario reveals. Survivability describes outcome under stress, not the quality of decisions that produced the system.

Survivability labels are often read independently of the assumptions that produced them. The assumptions are essential to interpretation. A finding that custody survives assumes particular actors are available, particular documents are discoverable, particular services remain operational, and particular timeframes are respected. Strip away the assumptions and the finding loses meaning. Yet readers frequently encounter the label without the assumptions, either because the assumptions were not transmitted or because they were skipped during review.

Survivability is interpreted as endorsement when encountered by third parties without context. An attorney reviewing estate documents sees a survivability profile. The attorney has no relationship with the original assessment and no exposure to the methodology. The word "survives" reads as approval. The attorney may rely on that perceived approval when advising clients, not recognizing that the assessment described behavior rather than recommending structure.

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Why Interpretation Fails

The dynamics of interpretation failure around survivability are structural rather than incidental. They arise from the gap between how the term is defined and how it is naturally read.

The system models how custody behaves under explicitly defined stress, not how it performs in general. The assessment does not evaluate the system across all possible conditions. It selects a scenario, defines assumptions, and observes behavior within that frame. Performance outside the frame is not measured and cannot be inferred from performance within it. General reliability is a different question than scenario-specific survivability.

Survivability modeling observes behavior under constrained assumptions that may not recur. The scenario assumes particular conditions: a specific trigger event, a specific set of actors, a specific information state, a specific timeline. These conditions are chosen to be realistic but are not predictions. Actual events may diverge. The assumptions that produced the finding may never manifest in the form the model anticipated.

Survivability outcomes are conditional on timing, availability, authority, and human behavior. Each of these factors can change independently. Timing affects whether actions can be taken before constraints bind. Availability determines whether necessary actors and artifacts are present. Authority governs whether legal and operational permissions align. Human behavior introduces variance that models cannot fully capture. A survivability finding holds only while these conditions remain consistent with the assumptions.

Meaning degrades when survivability is detached from its scenario framing. The scenario is not a backdrop; it is the definition. Survivability outside a scenario is undefined. When the scenario is omitted, forgotten, or misunderstood, the term loses its referent. What remains is a word that sounds positive but no longer points to a specific observation.

Third-party readers infer normative meaning when definitions are absent. Without explicit definition, readers supply their own. The everyday meaning of "survive" is normative—it implies success, continuation, positive outcome. Third parties who encounter survivability language without the assessment context read it through this normative lens. They believe something has been evaluated and approved, when in fact something has been modeled and described.

Language implies durability unless explicitly bounded by scope and time. Words persist. Documents circulate. A survivability finding made in 2023 may be encountered in 2028 without any indication that it has expired or that circumstances have changed. The finding reads as current because nothing in its form signals otherwise. Readers assume validity unless told otherwise, and the document does not tell them otherwise on its own.

Stress modeling captures one slice of possible failure space, not the full surface. The assessment examines behavior under defined stress. It does not examine behavior under stress that was not defined. Other scenarios, other triggers, other failure modes remain outside the model. A system that survives the modeled scenario may fail under adjacent scenarios that were not tested. The model illuminates one region while leaving others in darkness.

Modeled survivability can coexist with unmodeled collapse. A system can be survivable under the death scenario and vulnerable under the incapacity scenario. It can survive orderly succession and fail under contested succession. It can survive with current service providers and fail if those providers change terms or cease operation. The survivability finding does not preclude failure; it describes behavior under one set of conditions while remaining silent about others.

Interpretation drift introduces reliance risk that the system does not model. As survivability language moves through conversations, documents, and decisions, its meaning shifts. Each reader adds their own interpretation. Each transmission loses context. By the time the term reaches a decision point, it may carry connotations the original assessment never intended. Reliance based on drifted meaning creates risk the assessment cannot account for.

Guarantees are inferred when survivability is treated as a property rather than an observation. A property belongs to the system. An observation belongs to the assessment. Survivability is an observation: the system behaved this way under these conditions at this time. Treating it as a property—something the system possesses durably—converts an observation into an expectation. Expectations invite reliance. Reliance based on misclassified observations produces outcomes the assessment did not promise.

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Conclusion

The definition of survivability applies only within the stated assumptions and does not persist beyond them.

Survivability describes modeled behavior under stated stress conditions at a point in time. It is an observation, not a property. It is bounded, not general. It is descriptive, not evaluative. Recognizing these constraints allows survivability findings to be read for what they describe rather than what they appear to promise.

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System Context

Examining Bitcoin Custody Under Stress

Bitcoin Custody Maturity Level as an Imported Framework

Bitcoin Custody Risk Assessment as Exposure Mapping

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