HMAA (Hierarchical Mission Authority Architecture) is a deterministic authority-management framework for autonomous systems operating in safety-critical and contested environments. This deposit contains the HMAA Technical Assurance Report v2.4.2, which specifies and evaluates an authority engine that computes a scalar authority value A ∈ [0,1] from four inputs: Q: operator quality C: context confidence E: environmental threat τ: sensor trust The engine uses a multiplicative base × gate × damping × τ structure with an Environmental Warning (EW) hysteresis state machine and a five-tier authority classification (T0–T4). The report includes: A complete, self-contained piecewise mathematical specification of the engine (eng()), sufficient for independent re-implementation Explicit EW hysteresis rules and dynamic weighting under EW A deterministic boundary test suite (10 test vectors) covering invariant boundaries, EW thresholds, and guard behavior Monte Carlo simulations with reproducible CLI commands and a fixed canonical seed A formal safety assurance case (hazards H1–H5b), plus an FMEA and threat model An Evidence Register mapping claims to CLI runs and content-stable SHA-256 hashes (excluding timestamp/run_id) Scope / limitations: This is a software model and simulation report (not a certified flight computer). Safety properties are empirically validated using Monte Carlo tests plus deterministic boundary vectors; formal proof and hardware-in-the-loop validation are listed as future work. How to reproduce (high level): The report provides command-line invocations for the core scenarios (CI gate, adversarial Monte Carlo, EW hysteresis stress, nominal scenario) and expected summary statistics.