docs: add claim boundary

Author: LalaSkye

CLAIM_BOUNDARY.md

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+# Claim Boundary
+
+Date: 2026-05-11
+Repository: `LalaSkye/execution-boundary-lab`
+
+## Purpose
+
+This file keeps the repository's claim surface bounded to deterministic failure demonstration and conformance-surface work.
+
+## Allowed claims
+
+This repository may be described as:
+
+- a bounded artefact
+- a deterministic failure harness
+- a path-local demonstration
+- a conformance test surface
+- a research architecture work surface
+- a negative-case inspection surface
+
+## Mechanism claim
+
+Safe wording:
+
+> `execution-boundary-lab` demonstrates that syntactically valid structured inputs can produce unintended state changes when they reach execution without upstream admissibility gating.
+
+## Evidence claim
+
+Safe wording:
+
+> The repository provides contaminated cases, a naive executor, traces, and tests that make the failure mode inspectable.
+
+## Forbidden claims
+
+Do not claim:
+
+- adoption
+- validation
+- endorsement
+- certification
+- compliance
+- production readiness
+- field impact
+- proven market demand
+- path-universal coverage
+- standardisation
+- production security coverage
+- that this repository includes the full Trinity gate implementation
+
+## Comparison boundary
+
+Do not use this repository to attack or rank other projects.
+
+If another system is relevant, treat it as a separate artefact lane requiring direct inspection.
+
+## Public sentence
+
+> This is a deterministic negative-case harness: it shows what can go wrong when admissibility is absent before execution.
+
+## Stop line
+
+If the evidence is not in the cases, tests, traces, specification, or receipt, do not claim it.