Decision Logs: Capturing the 'Why' Behind Code Changes

What this article solves: Six months from now, nobody will remember why you chose Redis over Memcached—unless the decision left receipts. This guide covers automated decision logs from the places your team already argues productively.

Who this is for: Tech leads who want ADRs without assigning a part-time historian.

The problem with manual decision logs

Manual ADRs die because they compete with shipping.

Teams either:

Code changes daily. Memory does not.

Where decisions actually happen

SourceWhat you capture
**GitHub** PR + reviewApproach, rejected alternatives, merge proof
**Slack** threadFast tradeoffs, incident-driven reversals
**Fathom** (or call notes)"We agreed to delay the migration" that never became a ticket
**Confluence**Stakeholder-facing decision record for compliance
**Linear / Jira**Business scope and "we shipped X for ticket Y"

You rarely need all five in one entry. A schema decision might be PR + Supabase migration link. A product pivot might be Fathom summary + Notion RFC + PR.

What a good automated decision entry looks like

  1. One-sentence decision — "Use idempotency keys on webhook handler"
  2. Tradeoffs — pulled from review comments, not invented
  3. Sources — clickable PR, thread, call summary, wiki page
  4. Status — superseded when a later PR reverses it (link forward)

If an engineer cannot verify in two clicks, it is marketing—not a decision log.

Fathom: decisions that never became tickets

The most expensive knowledge is what was said on a call and nowhere else.

Connecting Fathom lets meeting summaries sit next to the PR that implemented (or blocked) the idea. Future you does not need to ask "what did we agree on in that roadmap review?"

Confluence: when the company still wants a wiki face

Confluence pages are often the audit-friendly version of a decision. Great—keep them. Just do not type them from memory every Friday.

Generate the engineer-facing log from GitHub and Slack; link to Confluence for the polished narrative. One brain, two audiences.

Setup checklist

The outcome

New hires read why, not just what. Incident responders see which decision created the fragile edge. Auditors follow Confluence links to PR proof.

The why survives because it was never trapped in one person's head.

Capture decisions from your stack