Verirun gives a coding agent an agent-independent way to prove that the software it just built actually behaves correctly — by launching the app, driving it, and collecting its own evidence (UI tree, filesystem, SQLite, process state, logs), then producing a verdict-of-record the agent cannot fabricate through the MCP/API surface.

The agent connects to Verirun as an MCP (stdio) client. It is treated as an untrusted planner: it may request actions and relay requirements, but every receipt, observation, and verdict is stamped by Verirun itself. A requirement the agent relays carries no authority — a CONFIRMED verdict comes only from Verirun's own invariants (e.g. "the target must not crash or hang") or from a requirement the user authored directly.

What it is (and is not)

Is: independent evidence collection + an auditable verdict-of-record. When the UI says "Saved" but the file was never written, Verirun catches it from the filesystem — not from the app's own claim (receipt ≠ effect).
Trust boundary (V0, stated honestly): the run record is protected against fabrication via the MCP/API surface. It does not detect out-of-band tampering by another same-user process with file-write access. This is a TCB limitation, published as-is — not a marketing claim.

Requirements

Windows 10/11.
Node.js ≥ 22. On an LTS Node, the native dependency (better-sqlite3) installs from a prebuilt binary — no C++ build tools needed. On a brand-new non-LTS Node a prebuild may not exist yet; use an LTS Node or install the Windows build tools if the install falls back to compiling.

Quick start

# Run the MCP server (stdio). Point your coding agent's MCP config at this.
npx verirun mcp

# Environment self-check.
npx verirun doctor

Before publishing a release, run a manual pre-publish smoke: npm ci → npm test → npm pack → install the tarball on a clean prefix → verirun doctor. Publish by hand with npm publish --provenance and 2FA.

Claude Code — .mcp.json
Codex — MCP server config
Cursor — mcp.json

How a run works

verify_begin — declare the workspace + the scope paths this run may touch, and for a web app the declared_endpoints it may read. Over-broad scope (drive root, user profile, workspace root, wildcard hosts) is refused.
target_launch — Verirun launches the app and starts a supervised watcher.
Drive the app: ui_inspect, ui_search, ui_act (tiered input), wait_until. ui_inspect walks the full depth by default and bounds the reply by node count instead — truncatedNodes says how many it left out, and max_nodes raises the budget when you want the whole tree. Chromium-backed UIs (Electron apps, web pages) build their tree lazily, so the walk repeats until two passes agree across a real pause — settle_gap_ms tunes that pause and treeSettled reports whether they ever agreed, with the whole settle capped at six seconds. Starting a Chromium target with --force-renderer-accessibility makes its tree complete from the first query, and Verirun says so when the flag is missing rather than adding it for you: changing how the app under test runs is not a runtime's call. For a targeted lookup at any depth, use ui_search.
Assert on evidence: observe_filesystem, observe_sqlite, observe_logs, observe_http, assert_evaluate — the evaluator collects its own evidence; cherry-picked agent references cannot steer the result. A web app keeps its effect on a server, so observe_http reads the endpoint itself: GET/HEAD only, no ambient credentials, and redirects are reported rather than followed, so a 3xx cannot carry the read outside what you declared. It needs the net_read capability, which is never granted by default. Declare a host by IP and no name resolution is involved at all; declare it by name and it is pinned to the addresses it resolved to when scope was granted, so a later DNS change refuses the read instead of following it elsewhere. A deployment that legitimately rotates addresses (a proxy or CDN) can be allowed to move with VERIRUN_ALLOW_ENDPOINT_REPIN=1 — a user-side setting, never agent-declarable — and every move is recorded in the run.
verify_finalize — Verirun writes the verdict-of-record (report.md + verdict.json) and tears the run down. A run whose scripted action came back other than EXECUTED cannot tell a wrong app from a scenario that never happened, so a missing effect is reported INCONCLUSIVE with the unexecuted steps named — never as a suspected app defect.

Inspect any run's evidence chain, trust-tagged by origin:

npx verirun show <run-id>

An agent cannot know which account you test with and must never hold your secret, so auth lives on your side. Write http-auth.json in the run store (verirun doctor prints the path and the exact shape):

{
  "staging-api": {
    "header": "Authorization",
    "secret": "Bearer <token>",
    "endpoint": "https://staging.example.com/api"
  }
}

A short-lived token (OAuth, a signed session cookie) goes in as a command instead of a value — its stdout is the secret, cached for ttl_seconds:

{
  "oauth-api": {
    "header": "Authorization",
    "secret_command": "gcloud auth print-identity-token",
    "ttl_seconds": 300,
    "endpoint": "https://api.example.com/v1"
  }
}

The agent then passes auth: "staging-api" to observe_http or an http_response assertion — a name, never a value. Each profile is bound to the endpoint prefix it may be sent to, so an agent cannot point your token at a server of its choosing; cleartext http is accepted for loopback only; if the endpoint echoes the secret back, it is scrubbed out of the body before the agent or the run record sees it; and when an auth command fails, the agent is told the exit status and nothing more — run the command yourself to see why.

Input tiers (Windows)

Tier A — UIA patterns (invoke / set-value): targeted, no synthetic input.
Tier B — post-message keyed input: HWND-targeted, no focus steal (cannot type into most text boxes — measured).
Tier C — send-input / click: OS-wide, steals focus, can interleave with your typing. Off unless VERIRUN_ALLOW_INPUT_INJECTION=1 (a user-side setting, never agent-declarable), with a focus pre-check and abort-on-focus-loss.

Telemetry

Opt-in only. Nothing is collected or transmitted by default. verirun telemetry on starts local metric capture you can inspect with verirun telemetry show; V0 has no network sink.