Semantic Diff

A Semantic Diff is a diff by meaning, not by file. A line diff shows that text moved. A semantic diff shows how the intent changed: which guarantees were added, which never rules were weakened, which proof went stale.

Part of the family of concepts for working with large changes.

Why meaning, not lines

The changes that matter most in a review are often invisible in a line diff:

• A never rule quietly weakened from "never log the token" to "never log the token in production."
• A guarantee removed as a side effect of a refactor.
• A proof artifact that went stale because the code moved underneath it.

A line diff shows churn. A semantic diff shows the change in trust.

Shape

Semantic diff (since HEAD~1)
  15 missions changed
  10 guarantees added
  8 never rules added
  0 never rules weakened
  14 verification rules added
  1 proof artifact became stale
  3 new chains created

The line that matters most is often the smallest: 3 never rules weakened is a one-word change in the text and a major change in trust.

In review

Semantic Diff is how IntentLang improves both code review and release review. A reviewer reads what changed about the intent first, then drills into the code for the changes that actually move risk. It pairs with the Build Session Digest (what changed this session) and the Proof Matrix (what is verified now).

Worked example

The semantic-diff block in examples/mvp-customer-portal/intent-session-summary.json shows the shape for the customer portal's first session.

Where it comes from (planned)

intent diff ./intent --since HEAD~1 is a planned command owned by the SkillsTech Compiler. This repo teaches the concept and ships the example fixture.