DEV Community

Yurukusa
Yurukusa

Posted on • Edited on

Single Source of Truth: The Concept Non-Engineers Don't Know (But Should)

#claudecode #ai #productivity #beginners

The "Final Version" Problem

Does this look familiar?

schedule_april.xlsx
schedule_april_revised.xlsx
schedule_april_revised2.xlsx
schedule_april_tanaka_checked.xlsx
schedule_april_FINAL.xlsx
schedule_april_FINAL_actually_final.xlsx
Enter fullscreen mode Exit fullscreen mode

This isn't an extreme example. This is happening in some workplace right now.

Engineers have a name for this chaos: the absence of SSOT.

What Is SSOT?

Single Source of Truth - one location holds the authoritative version of any given piece of information. Everything else either points to it or is generated from it.

That's it.

"The correct shift schedule lives here." "The latest meeting notes are here." "This number comes from here." - deciding on a single "here" is practicing SSOT.

How I Encountered This Concept

I built a shift optimization tool with Claude Code for a daycare center (140 children, ~40 staff). The system needed to handle part-time fixed schedules, rotation schedules, room-by-room staffing requirements, and 15-minute interval attendance counts.

Claude Code proposed this structure:

YAML config file (staff info, constraints) ? This is the SSOT
        ?
  Python script (auto-calculation)
        ?
  Excel output (display only)
Enter fullscreen mode Exit fullscreen mode

The YAML is the "one true source." Excel is just output - generated from the YAML. Edit the Excel directly and the next run overwrites it. Want to change data? Change the YAML.

That's when I understood why schedule management had always been chaotic.

Multiple people editing their own copies of an Excel file, with no clear answer to "which one is correct" - that's SSOT fragmented across a dozen files.

SSOT Is Everywhere in AI-Assisted Work

Once I started using Claude Code seriously, SSOT appeared everywhere.

CLAUDE.md - All instructions to Claude Code live here. One file. If I put conflicting instructions in multiple places, the AI gets confused. One file = one source of truth for AI behavior.

content-manifest.yaml - I publish articles to Zenn, Qiita, note, and dev.to. URLs, draft paths, publish status - all in one YAML file. "Did I publish that article to Zenn?" is no longer a question.

git - Every engineer knows this, but the concept is pure SSOT: the repository is the single authoritative version of the code. Local changes don't "count" until they're committed.

Why This Matters for Non-Engineers

Engineers absorb SSOT naturally while learning to code. It never gets written up as a concept worth teaching.

But non-engineers are running entire operations without it.

The Excel spreadsheet copied into three team members' inboxes. The schedule posted in Slack, printed on paper, and entered into Google Calendar. The budget tracked in one sheet, reported from a different sheet, analyzed in a third sheet - all manually kept "in sync."

When you understand that the chaos has a name - and a solution - the fix becomes obvious: pick one place and make everything else reference it.

The First Step

You don't need new software. You need a decision.

  • This Google Sheet is the authoritative schedule. No other document is edited directly.
  • This Notion page is where meeting notes live. Slack summaries link to it, not duplicate it.
  • This spreadsheet column is the source for this number. Reports pull from it, not copy it.

You won't get it perfect. That's fine. Even declaring "this is the source" cuts most of the confusion.

Summary

Single Source of Truth (SSOT): Any piece of information exists in exactly one place. Everything else is derived from or references that one place.

For engineers, obvious. For non-engineers, a genuine revelation.

I discovered this concept while building a shift scheduler with AI. The moment I understood it, I saw it everywhere - and started applying it to everything.

This is part of the series "Engineering Concepts I Learned Working with AI (as a Non-Engineer)".

Tools mentioned:

  • cc-health-check - 20-point Claude Code environment diagnostic. Browser-based, no install.
  • claude-code-hooks - Hook collection to prevent AI agent runaway. Cost alerts, deadlock prevention, logging.

More tools: Dev Toolkit - 56 free browser-based tools for developers. JSON, regex, colors, CSS, SQL, and more. All single HTML files, no signup.

Top comments (0)