Personal Self Digital Infrastructure

Abstract

Status of This Document#

This document is a Published Standard of the PSDI category, authored and stewarded by Soma & Mio. It is not a W3C, IETF, or ISO standard. The term "standard" is used in the sense of a published category definition paper that establishes normative vocabulary and architectural requirements for a new software category.

Feedback and errata should be directed to [email protected]. Future versions will be published at psdi.mysoma.space/changelog.

§1 Introduction#

The proliferation of large language models and agentic AI systems has created the technical preconditions for a new category of personal software: systems that maintain persistent, context-aware digital representations of individual human identity across time, channels, and physical-digital boundaries.

Prior to PSDI, no formal standard existed for how such systems should be architected, what principles they must uphold, or how they should interoperate. The result has been fragmented implementations with incompatible identity models, inconsistent permission semantics, and no shared vocabulary for describing the components of personal digital identity infrastructure.

This specification addresses that gap. It defines the PSDI category, establishes normative requirements for conformant implementations, and provides a reference taxonomy that enables interoperability, auditability, and long-term continuity of personal digital identity.

§2 Normative Definition#

PSDI (Personal Self Digital Infrastructure) is the category of software systems that create, maintain, and govern persistent digital representations of individual human identity — called selves — across time, context, and physical-digital boundaries.

A system is PSDI-conformant if and only if it implements all five core principles defined in §7 and provides at least one self-domain as defined in §4.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.

§3 Scope#

This specification applies to:

• Software systems that instantiate persistent digital selves
• Protocols for cross-self interaction and permission delegation
• Data models for self-domain context and memory
• Interfaces between digital selves and physical embodiment systems

This specification does not govern:

• General-purpose AI assistants without persistent identity
• Social media profiles or public identity representations
• Enterprise identity management (IAM) systems
• Blockchain-based identity systems (unless also PSDI-conformant)

§4 Self-Domain Model#

A self-domain is the atomic unit of PSDI architecture. Each self-domain is an isolated context space with its own:

• Identity namespace and persistent context store
• Permission boundary (no implicit cross-domain access)
• Designated operator and fallback protocol
• Embodiment interface specification

Self-domains MUST NOT share authentication credentials. Cross-domain interactions MUST be mediated by an explicit permission grant that is logged and auditable.

§5 Eight Selves#

The PSDI taxonomy defines eight canonical self-domains that together constitute a complete personal digital identity infrastructure. These definitions are derived from the actual operational purpose of each domain — not from etymological inference. Implementations MAY instantiate a subset; however, all eight MUST be architecturally supported. The eight selves are organized into two identity lines: Self Identity Line (5) and Family Identity Line (3).

See §5 Extended Reference: Eight Selves for full specifications of each self-domain.

§6 Permission Model#

Cross-self interactions are governed by the PSDI Permission Model, which requires:

1. Explicit declaration: The requesting self MUST declare the specific data or capability it requires from the target self.
2. Scope limitation: Granted permissions MUST be scoped to the minimum necessary for the declared purpose.
3. Auditability: All cross-self interactions MUST be logged with timestamp, requesting self, target self, and granted scope.
4. Revocability: Any granted permission MUST be revocable by the self owner at any time without requiring the requesting self's consent.

§7 Five Core Principles#

A PSDI-conformant system MUST implement all five core principles. These principles are normative and non-negotiable; partial compliance does not constitute PSDI conformance.

§8 Compliance Requirements#

To claim PSDI conformance, an implementation MUST:

1. Implement all five core principles (§7)
2. Provide at least one self-domain with a defined permission boundary
3. Maintain a durable context store with documented retention policy
4. Implement and document a crisis handoff protocol
5. Provide an embodiment interface (even if not currently connected to physical hardware)

Use the PSDI Compliance Self-Assessment to evaluate your implementation against these requirements.

§9 Versioning#

PSDI versions follow semantic versioning (MAJOR.MINOR). Breaking changes to normative requirements increment MAJOR. Additive clarifications increment MINOR. The current version is 1.0.

Implementations claiming conformance MUST specify which version of the standard they conform to. See Changelog for version history.

§10 Stewardship#

The PSDI standard is stewarded by Soma & Mio as the Category Definer. The steward is responsible for:

• Maintaining the normative specification
• Publishing errata and new versions
• Operating the reference implementation
• Reviewing adoption declarations

See Steward Reference for contact information and governance procedures.

References#