Quickstart

Set up the workspace, then scaffold a hub — a markdown file whose frontmatter anchors sentences to code:

surf init              # writes surf.toml + creates hubs/
surf new auth          # creates hubs/auth.md

Edit it: write a claim and point at: at the symbol it describes.

---
summary: How auth refresh rotation works.
anchors:
  - claim: refresh rotation is single-use; reuse triggers global logout
    at: src/auth/refresh.ts > rotateRefreshToken
---

# Auth

Prose a human (or agent) reads to understand this domain.

Then drive the loop:

surf lint     # does every anchor resolve to exactly one symbol?
surf check    # the gate — a brand-new claim is "unverified" until you seal it

UNVERIFIED  hubs/auth.md :: src/auth/refresh.ts > rotateRefreshToken
    run `surf verify`

You’ve read the prose and confirmed it’s true, so seal it — this writes the hash back into the frontmatter (verify only touches that one line):

surf verify
surf check    # surf check: all anchored spans match their stored hashes.

Now change the logic of rotateRefreshToken and run the gate again:

$ surf check
DIVERGED  hubs/auth.md :: src/auth/refresh.ts > rotateRefreshToken
    stored 9b1c33ade8f1 → now 4d5e6f2a0b7c  (magnitude: Small)
    claim: refresh rotation is single-use; reuse triggers global logout
surf check: 1 divergence(s).

The merge is blocked (non-zero exit) until someone re-reads the sentence. If it still holds, surf verify re-seals; if it’s now false, fix the prose first. Reformatting, comments, or renaming a local variable do not trip it — only logic does.

Machine-readable output for tooling and the optional reviewer plugin:

surf check --format json

{
  "version": 1,
  "divergences": [
    {
      "hub": "hubs/auth.md",
      "claim": "refresh rotation is single-use; reuse triggers global logout",
      "at": "src/auth/refresh.ts > rotateRefreshToken",
      "kind": "changed",
      "old_hash": "9b1c33ade8f1",
      "new_hash": "4d5e6f2a0b7c",
      "new_code": "function rotateRefreshToken(...) { ... }",
      "prose": "refresh rotation is single-use; reuse triggers global logout",
      "magnitude": "small"
    }
  ]
}

Next: Authoring hubs for writing good claims and choosing granularity, or the Command reference.