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

Source: Dev.to

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

This isn’t an extreme example; it’s happening in many workplaces right now. Engineers call this chaos the absence of a Single Source of Truth (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.

“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.

What Is a Single Source of Truth?

• Definition: Any piece of information exists in exactly one place. All other copies are derived from or reference that place.
• Benefit: Eliminates confusion about which version is correct.
• Result: Even a simple declaration like “this is the source” cuts most of the chaos.

Real‑World Example: Shift Scheduler

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
• 15‑minute interval attendance counts

Claude Code suggested the following architecture:

flowchart TD
    A[YAML config file (staff info, constraints) – SSOT] --> B[Python script (auto‑calculation)]
    B --> C[Excel output (display only)]

• YAML is the one true source.
• Excel is just output, regenerated from the YAML each run.
• Editing the Excel directly is futile; the next run overwrites it.
• Want to change data? Change the YAML.

Once I adopted this approach, SSOT appeared everywhere:

Engineers absorb SSOT naturally while learning to code, but non‑engineers often run entire operations without it.

Where SSOT Shows Up in Everyday Work

• Schedule: A single Google Sheet is the authoritative schedule; no other document is edited directly.
• Meeting notes: A Notion page holds the notes; Slack summaries link to it instead of duplicating content.
• Key numbers: A specific spreadsheet column is the source; reports pull from that column rather than copy values.

You don’t need new software—just a decision about where the “source” lives and a commitment to reference it everywhere else.

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).