Technical due diligence exists to answer one question: will the technology support the plan the valuation assumes? A quick look at the repo does not get you there. Here is the real scope.
Architecture and scalability
Can the current design carry the projected load, or is there a rewrite hidden in the roadmap? Reviewers look at the data model, the service boundaries, single points of failure, and the honest answer to “what breaks first at 10x.”
A system that needs re-platforming to hit its own targets is a material finding, not a footnote.
Code health, tests, and delivery
Test coverage on the paths that matter, a CI/CD pipeline that actually gates releases, dependency and licence hygiene, and how long it takes a new engineer to ship their first change. These predict how fast the team can execute post-deal.
Security, compliance, and key-person risk
Authentication and secrets handling, data-at-rest and in-transit encryption, the applicable compliance regimes and the gap to them, and — often the biggest risk — how much critical knowledge lives in one person's head with nothing written down.
Good diligence produces a ranked list of findings with cost-to-fix estimates, not a pass/fail stamp. That list is a negotiating input and a first 90-day plan.