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Origin tracing

Every bugfix has a hidden backstory. Someone shipped the bug — in some PR, on some day, probably with an approving review. But by the time the fix merges, nobody's asking where the bug came from; everyone has moved on. Which means the most valuable lesson in the whole incident goes unlearned.

Origin tracing recovers that backstory. Point it at a bugfix PR and it traces each meaningful line the fix touches back through the repository's history to the pull request(s) that originally introduced the buggy code — and then shows you how risky those PRs scored when they were analyzed.

What a trace looks like

A finished trace leads with a plain-language summary:

This bugfix corrects 18 lines originally introduced by 3 pull requests — 2 of them scored High or Critical, accounting for 14 of the 18 traced lines.

Read that again, because it's the punchline of the whole product: the risky PRs Firetrail flagged months ago are the ones your team is now paying to fix. That's Future Debug Cost stopping being a theory and becoming a receipt. (And when a low-scoring PR turns out to be a bug origin, that's honest feedback about the score's limits — you'll see that too. The aggregate record lives in Business Impact.)

Each origin PR, in detail

Below the summary, every origin PR gets a card:

  • its number, title, and author — the full context of the original change,
  • the lines fixed here that it introduced — the specific overlap between that PR and this fix,
  • its risk score at the time, with a partial badge if it was a very large PR that got a partial analysis,
  • its top risk drivers as chips — what kind of risky it was, and
  • an expandable list of the files this fix touches from that origin.

Running a trace

On a bugfix PR, use the 🔥 Trace Origins action. Tracing runs in the background and narrates its progress — "Blaming changed lines → finding origin PRs" → "Analyzing origin PRs' risk" → "Done" — so you can see where it is on a large fix.

The connection also works in the other direction, automatically: when a new PR edits code that a past bugfix traced back to, the PR analysis view shows a risky history callout — this area has bitten you before — with links to those bugfixes.

Availability

Origin tracing is included on the Business plan. See Plans & billing.