Single source of truth: keep one version of every decision

A single source of truth is the one agreed place that holds the current version of a piece of information; every copy defers to it. This guide shows why documentation drifts away from it, and how to keep it, for people and for the AI agents that now read the same documents.

Updated on 22 October 2026.

What a single source of truth means

The idea comes from data systems: each fact is stored once, and everything else refers to it. In documentation it means that for every decision, spec or rule, there is one document the team trusts, and other documents link to it instead of repeating it.

It does not mean one giant document, nor one tool for everything. It means that when two pages disagree, everyone knows which one wins, and the other is either fixed or clearly marked as old.

Why documentation drifts

Copies: a paragraph pasted into a brief, a slide or a ticket becomes a second version the moment the original changes.
Decisions made elsewhere: a call or a chat thread changes the plan, and the document is never updated.
No owner: a page everyone can edit and nobody answers for slowly stops being true.
Explorations that look final: three drafts of the same idea, none of them marked as a draft.
AI agents reading everything: an assistant given the whole wiki can quote an abandoned draft as confidently as the decision that replaced it.

Seven practices that keep one version

1. Give every document an owner

One named person answers for each document’s accuracy. Others can edit it; the owner decides when it is right.

2. Mark what is decided and what is not

Label each document as canon (the decision), exploration (a draft or an option), obsolete, or superseded by another document. A reader, or an agent, should never have to guess.

3. Link instead of copying

Where a brief needs the pricing rules, it links to the pricing spec. If a summary helps, say where it comes from and when it was written.

4. Write decisions where they will be read

Keep a decision log, or a decision record per important choice, linked from the documents it changes. The meeting is where a decision is made; the document is where it lives.

5. Supersede, do not delete

When a document is replaced, mark it superseded and point to its successor. The old reasoning stays available, and nobody mistakes it for the current one.

6. Review on a rhythm

Ask a named reviewer to approve important documents, and look again when the work they describe changes. A document’s date and status should say how fresh it is.

7. Give AI agents the source, not a copy

Connect assistants to the documents themselves, with the reader’s permissions, rather than pasting snapshots into chats. Tell them which documents are canon, and treat what they write as a draft until someone approves it.

Set it up in a week

List the ten documents your team relies on most, and give each an owner.
Mark each one canon, exploration or obsolete. Merge or retire duplicates, and mark the retired ones superseded.
Replace pasted passages with links to their source.
Start a decision log, and link this week’s decisions to the documents they change.
Connect your AI tools to the documents, and tell them to prefer canon.

How Nodary helps

Truth status: each document can be marked canon, exploration, obsolete, or superseded by another, and agents are told a document’s status before they read it.
Contradictions: when two documents disagree, Nodary shows both passages side by side, word for word, and proposes a resolution only when you ask.
Links and backlinks: a [[link]] points to the source, and each document lists what links to it, so you see what a change affects.
Reviews: you name one owner or admin of the workspace or of the document’s project, or ask them all; one of them approves the document or asks for changes, signed with who and when, and the person who asked decides only when nobody else can.
History: each editing session of up to ten minutes and every agent write make a version; a document keeps its 50 newest by people and its 50 newest by agents, so you compare versions and restore one.
Agents with permissions: Studio AI and the agents connected over MCP read the documents themselves, with the permissions of the person behind them.

What Nodary does not do: it does not decide what is true. A person sets a document’s status, and a contradiction is resolved only when someone chooses to.

Try it on your own documents. The Free plan needs no card.

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Common mistakes

Declaring one tool the source of truth while decisions keep living in chat.
Making the single source one huge document nobody can maintain.
Deleting old versions, which hides why things changed.
Assuming an AI assistant knows which document is current.

Questions

Is a single source of truth one tool or one document?

Neither, necessarily. It is one agreed place per piece of information. A team can use several tools, as long as each fact has one home and everything else links to it.

How is it different from a knowledge base?

A knowledge base is where a team keeps what it knows; a single source of truth is a rule about it: each fact lives once, and copies defer to it.

How do AI agents fit in?

Agents read the same documents as people, so they inherit the same problems. Give them the source rather than copies, mark what is canon, and review what they write before it becomes the source.

What should happen to outdated documents?

Mark them obsolete or superseded and point to what replaces them. Keeping them, clearly labelled, preserves the reasoning without misleading anyone.