---
id: "first-revision-safe-write"
type: "guide"
title: "Perform a first revision-safe read/write"
summary: "Read a record, write with expected revision, verify."
why: "Revision preconditions prevent lost updates."
audiences: ["developers"]
related: ["record-revisions"]
invariants: ["Never omit expected revision on conditional writes"]
---
# Perform a first revision-safe read/write

Read a record, write with expected revision, verify.

## Why this path

Revision preconditions prevent lost updates.

## Invariants

- Never omit expected revision on conditional writes

## Steps

1. **Read current record and revision** — Revision N known
2. **Write with expected revision N** — Success or conflict

## Verification

- Record shows revision N+1 on success