assure

The user has a BEFORE and an AFTER — two directories, two commits checked out side by side, a legacy system and its migration — and wants to know whether the AFTER still does what the BEFORE did. You declare how the two are observed; INVARA decides. Quote its words exactly.

0. The tool

export PYTHONPATH="${CLAUDE_PLUGIN_ROOT}/src"        # bash / zsh

$env:PYTHONPATH = "${CLAUDE_PLUGIN_ROOT}/src"        # PowerShell

Every step is python -m invara assure <step> ... --db .runtime/verify.db. Runs are local and offline; a request to any host but loopback makes a run UNVERIFIABLE.

1. Declare the two systems and how they are observed

Write the Equivalence Manifest (.invara/assure.manifest.json). It names both systems, how an input reaches them, which probes observe them, which policies relax exact comparison and why, and which claims are mandatory.

{
  "schema_version": "invara.assurance.manifest/1",
  "session_id": "migration-2026-09-03",
  "source_system": {"id": "before", "kind": "process", "command": ["python", "legacy.py"], "root": "$SOURCE_ROOT"},
  "target_system": {"id": "after", "kind": "process", "command": ["python", "-m", "newapp"], "root": "$TARGET_ROOT"},
  "input_domain": {"kind": "corpus", "delivery": "stdin_json", "corpus": [{"id": "c1", "input": {"...": "..."}}]},
  "probes": [
    {"id": "cli", "adapter": "process", "capture": ["stderr"], "mandatory": true},
    {"id": "out", "adapter": "json", "source": "stdout", "mandatory": true}
  ],
  "policies": [],
  "claims": [
    {"id": "corpus", "kind": "corpus_equivalence", "mandatory": true},
    {"id": "search", "kind": "counterexample_search", "mandatory": true, "params": {"runs": 100, "seconds": 300, "seed": 1}}
  ]
}

When the whole input space is small and enumerable, declare it and ask for a proof instead of a search:

"input_domain": {"kind": "finite", "delivery": "stdin_json", "finite": {"parameters": {"zone": {"range": [1, 5]}, "express": [false, true]}}},
"claims": [{"id": "domain", "kind": "finite_domain_proof", "mandatory": true}]