sem

sem — Semantic Version Control

sem extends Git with entity-level operations. Instead of "lines 43-51 changed", it tells you "function validateToken was modified in src/auth.ts". It parses 30+ languages via tree-sitter and works in any Git repo with no setup.

When to reach for sem

• User asks "what changed in this commit / PR / branch?"
• User wants to know what will break if they change a function
• User asks who last touched a function or class
• User wants to trace how a function evolved over time
• You need structured, token-efficient code context for an LLM subtask
• You're doing a code review and want entity-level signal, not line noise

Commands

sem diff — what changed?

sem diff                          # working tree changes
sem diff --staged                 # staged only
sem diff --commit abc1234         # specific commit
sem diff --from HEAD~5 --to HEAD  # commit range
sem diff file1.ts file2.ts        # compare two files (no git needed)
sem diff --format json            # structured output for further processing
sem diff --format markdown        # for PRs / reports
sem diff -v                       # verbose: word-level inline diffs
sem diff --file-exts .py .rs      # filter by extension

Change types: added, modified (structural vs cosmetic), deleted, renamed/moved.

sem impact — blast radius

sem impact validateToken          # everything affected if this changes
sem impact validateToken --deps   # direct dependencies only
sem impact validateToken --dependents  # direct dependents only
sem impact validateToken --tests  # affected tests only
sem impact validateToken --json
sem impact validateToken --file src/auth.ts  # disambiguate

Use this before refactoring or deleting a function to understand scope.

sem blame — who last touched this?

sem blame src/auth.ts             # entity-level blame for a file
sem blame src/auth.ts --json

Unlike git blame, this shows who last modified each function, not each line.