PDR-001: Single-user first; new features must not preclude multi-user

• Status: Accepted
• Date: 2026-07
• Related: #712 (multi-user umbrella), VISION.md (Current Posture)

Context

Multi-user support is a recurring community request (#712 tracks it), and it would be a deep platform redesign: auth, data scoping, permissions, and what "multi-user" even means for a privacy-first self-hosted tool (household/team vs. SaaS-style). That strategic call hasn't been made. Meanwhile, features keep shipping — and each one can silently bake in single-tenancy assumptions that make the future redesign more expensive.

Decision

Open Notebook remains a single-user product for now — but this is a directional constraint, not a verdict: new features must not gratuitously preclude multi-user. Concretely, when designing a feature, avoid hard-coding single-tenancy where a neutral choice costs the same: data models that could carry an owner scope, auth touchpoints that assume exactly one identity, global singletons for per-user state.

This record does not commit to building multi-user. It commits to keeping the door open until the vision call in #712 is made.

Alternatives considered

• Decide multi-user now — premature: the product core is still stabilizing (see Current Posture in VISION.md) and the design space (team vs. SaaS) is unresolved.
• Ignore it until decided — cheapest today, but every single-tenant assumption shipped becomes migration debt.

Consequences

• Card design/triage gains a concrete check: "does this preclude multi-user?"
• Slight design overhead on data-model and auth decisions.
• When the #712 vision call is made, a new PDR supersedes or extends this one.