When one agent writes both the code and its check, a pass only shows the two agree.
The check was written by
sdt captures your worktree as you work and grades each state, so sdt green can return the last one that passed.
Capture starts when you run sdt init and keeps going from then on.
sdt watch on Linuxsdt undo reverses any operation you runsdt is a separate version control system that grades every state as it happens, so you never search for a break.
Here is what to know before you run sdt init.
A moment is a content-addressed state of your working tree that sdt captures on its own, with a stable id and a timestamp. It is not a commit and never shows up in sdt log. A change is something you create and name yourself with sdt save.
Yes, sdt is its own version control system, with its own object store, history model and commands. Its git interop works in both directions without loss, so full history, branches and tags move either way, and sdt export <dir> writes a plain git repo whenever you want one. That interop is what makes switching reversible, rather than sdt being git underneath.
Automatic capture is macOS only, where launchd starts it after a file changes and it stops again once it is done. On Linux you run sdt watch in a terminal instead, and it does the same work for as long as it keeps running.
Grading does nothing until you tell it which command to run with sdt config checks.full "<command>". From then on, every check runs inside a throwaway copy-on-write clone, so it never touches your worktree and never makes your terminal wait.
When an agent writes both the code and the test, a pass only proves that the code agrees with its own test. That is why sdt attaches a warrant to every verdict, which rates it on independence, relevance and discrimination. Relevance comes from file access times and is a conservative over-approximation on file systems other than APFS, while discrimination is only measured when the check itself changed and reads as unknown otherwise.
git history is a sequence of commits, and a commit is too coarse to tell you which state broke something, which is why bisect has to go searching after a failure. sdt records every captured state with a graded verdict attached, so sdt green can return the last one that passed. The difference is in what each system records, rather than in how quickly it can search.
No, because there is no account, no server and no telemetry. Sharing happens peer to peer, and the optional relay is one you run yourself, which cannot read anything that passes through it.
sdt seal encrypts a file in place and records it in .sdtsealed, the manifest of what is sealed and who can read it, so only the ciphertext is ever captured or shared. Anyone holding a key can run sdt unseal to write the plaintext back out.
Download a binary from GitHub Releases, and run sdt update whenever you want to update it in place. superdetermine is licensed under Apache-2.0 and lives at plyght/superdetermine. It is still early and opinionated, so its interfaces may change.
sdt is free and open source, and if you already have it, sdt update brings it up to date.