# ADR 0005 — Math-stack selection for the Quantum Wildbeyond expansion ## Status Accepted (2026-06-10). Dependency installs pending capacity window; contracts in MODULE-CONTRACTS-2026-06-26.md §V2 are written against this decision. ## Context The expansion mandate supplies a 20-domain catalog of JS/TS math libraries (`math_libs.md` / key-libraries CSV) and asks for quantum, reaction-diffusion, graph-theoretic, geometric, audio-spectral, statistical, and lore systems. A deep-research pass over integration specifics was run; its **adversarial verification stage was killed by a session capacity limit, so its claims are recorded as plausible-but-unverified leads, not facts** (per Master File III: insufficient measurements mean UNKNOWN, not false). Decisions below therefore prefer options that are robust under uncertainty and isolate every dependency behind an owned facade (Master File II, law 4). ## Decisions | Domain | Choice | Rationale | | ------------------ | -------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Quantum register | **Pure TS statevector** (`src/math/quantum.ts`, n ≤ 8) | Research leads indicate `quantum-circuit` is ~14.5 MB unpacked CJS with antlr4 + mathjs runtime deps and no ESM/types — absurd cost for 32 amplitudes. 200 owned lines are faster, typed, testable, allocation-free. | | Reaction-diffusion | **CPU Gray-Scott** on Float32Array ping-pong → three `DataTexture` | gpu-io's three.js context sharing (initWithThreeRenderer / attachToThreeTexture / state resets) is real but unverified and adds GL state-management risk; 128² CPU is <0.5 ms every 2nd frame — comfortably in budget. gpu-io remains the documented upgrade path if grid size grows. | | Graph analysis | **graphology + graphology-communities-louvain + graphology-metrics** | Maintained, TS-native, exactly fits community/pagerank needs; runs on slow cadence (240/600 frames) so per-pass cost is off the hot path. | | Voronoi | **d3-delaunay** (+ @types if needed) | Canonical, tiny, built once over 24 static sites. | | Lore hashing | **@noble/hashes** (sha2/sha256) | Audited, zero-dep, sync, tree-shakable. | | Streaming stats | **simple-statistics** | Zero-dep functional API for regression/stddev on small rings. | | Audio spectra | **Native Web Audio AnalyserNode** | On the user's own catalog (§9); zero bytes, allocation-free polling into a pre-allocated Uint8Array. Meyda rejected as overweight for 4 bands. | | ODE integration | **Owned RK4** (if/when attractor ribbons land) | Fixed-step RK4 is allocation-free and sufficient for visualization; `ode45-cash-karp` allocates per call in a hot path. | ## Consequences - Bundle growth is bounded to small, typed, maintained deps; the two heavy candidates (quantum-circuit, gpu-io) are excluded with documented re-entry paths. - Every dep gets: facade module, NOTICE.md license entry, contract section. - If the deep-research claims are later re-verified and contradict any lead relied on here, this ADR must be amended before the affected system changes.