The artifact is rich because it has to be. A pull request title summarizes intent. The description articulates motivation. The diff captures the actual change. The review comments expose disagreement, trade-offs, and the things that almost shipped. The linked tickets connect the change to product context. Read together, a sequence of pull requests is a much higher-fidelity record of what a team is actually doing than the roadmap it is theoretically following.
What the product layer typically sees is the roadmap and the ticket queue. What it rarely sees is the PR stream. The result is a known gap: leadership thinks the team is building feature X (because feature X is on the roadmap), while the team is actually spending sixty percent of its cycle on a refactor that no roadmap captures. Both sides are operating in good faith; they just have different visibility into what the work actually is. Reading PRs as product signal closes the gap.
Roadmap drift becomes visible earlier when PRs are read this way. The pattern of code changes precedes the pattern of shipped features by weeks; if the PR stream shows the team systematically working on payments infrastructure when the roadmap says they are working on growth, the divergence is visible while it can still be discussed, rather than at the end of the quarter when the roadmap commitments come due. The leading indicator was always there; the product layer just was not looking at it.
Silent technical debt is the second thing that surfaces. Refactors, migrations, deprecations, and infrastructural cleanups all show up clearly in the PR stream and almost never on the roadmap. Treating them as invisible means the prioritization layer operates with incomplete information about cost — what looks like a small feature can be expensive because it touches infrastructure that is mid-migration, and the infrastructure is mid-migration because someone made the (correct) call to fix it, without that call appearing on any product surface.
The reverse is also true. Reading PRs lets product see the assumptions engineering is making. A PR title that says "add support for v3 of the auth API" implies that v3 is the path forward; if product had assumed v2 was stable, that assumption is now challenged. Most of these mismatches are small. The valuable ones are the ones that would have surfaced as a surprise three months later, and instead surface as a five-minute conversation on a PR review.