Example: AI agent loop

A runnable, self-contained demo of cadvm as the version / diff / verify layer under an AI-CAD agent — accept a good edit, catch and revert a regression. No LLM and no Open CASCADE: the part is an STL, so the geometric diff is pure Rust.

Script: examples/agent-loop.sh.

examples/agent-loop.sh    # after building or installing cadvm

What it runs

cadvm init
cadvm snapshot -m "baseline bracket"

# Agent adds a mounting boss → GATE: it must add material
cp block_v2.stl bracket.stl
cadvm snapshot -m "agent: add mounting boss"
cadvm verify HEAD~1 HEAD --expect 'added_tris>0'   # exit 0 = accept

# Agent regresses and drops the boss → GATE: nothing significant removed
cp block_v1.stl bracket.stl
cadvm snapshot -m "agent: regenerate (drops the boss)"
cadvm verify HEAD~1 HEAD --expect 'removed_tris<20' \
  || cadvm revert HEAD                              # exit 1 = revert

The accept/revert decision is driven by cadvm verify’s exit code — exactly the hook an agent or a CI gate uses.

What it prints

● baseline bracket committed

▶ Agent iteration: add a mounting boss
  verifying  added_tris > 0 …
  ✓ added_tris > 0   (actual 158)
  PASS (1 checks)
  ✓ accepted

▶ Agent iteration: (buggy) regenerates and loses the boss
  verifying  removed_tris < 20 …
  ✗ removed_tris < 20   (actual 158)
  FAIL (1/1 checks failed)
  ✗ regression caught — reverting to the good version

▶ The JSON an agent parses (verify --json):
{
  "file": "bracket.stl",
  "report": {
    "pass": true,
    "metrics": { "added_tris": 158, "removed_tris": 64, "unchanged_tris": 114,
                 "bbox_dx": 40, "bbox_dy": 30, "bbox_dz": 28 },
    "checks": [ { "metric": "added_tris", "op": "Gt", "expected": 0,
                  "actual": 158, "pass": true } ]
  }
}

▶ History (the bad iteration was reverted, the boss survives):
commit …  Revert "agent: regenerate (drops the boss)"
commit …  agent: regenerate (drops the boss)
commit …  agent: add mounting boss
commit …  baseline bracket

In an agent (via MCP)

The same loop runs as native tool calls — cadvm_snapshot, cadvm_verify, cadvm_revert — when cadvm is wired in as an MCP server.