> ## Documentation Index > Fetch the complete documentation index at: https://docs.solved.gg/llms.txt > Use this file to discover all available pages before exploring further. # Principles > Definitions of full ECMAScript compatibility, matrix honesty, Linux-only policy, and exclusive API filters for pre-v0.0.1. # Principles These rules apply to every pre-v0.0.1 initiative. They keep roadmaps testable and prevent silent overclaims. ## 1. Own engine scripty implements JavaScript in a **Zig-native VM**. We never embed or fork V8, JavaScriptCore, or SpiderMonkey. Bun-exclusive surfaces that historically depended on JSC are implemented by **behavior compatibility** on scripty’s engine, not by shipping JSC. ## 2. What “fully compatible with the latest ECMAScript” means | Term | Definition | | ------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Latest edition** | The yearly ECMA-262 snapshot we claim. **Pinned baseline: ECMAScript 2026** (17th edition, June 2026; HTML [262.ecma-international.org/17.0](https://262.ecma-international.org/17.0/); program pin date 2026-07-17). | | **Re-pin** | When Ecma publishes a new edition, open an explicit re-pin task and finish the [Sources](/scripty/v0.0.1-dev/reference/sources) checklist **before** any release claims the new edition. | | **Oracle** | [Test262](https://github.com/tc39/test262) language tests for the pinned edition. | | **In-scope** | Language syntax, semantics, and built-ins required by the edition, plus Annex B only where we **opt in** and document it. | | **Out of scope for the ES bar** | Browser/Web IDL globals (DOM, `window`, …), HTML host hooks, and features we mark refused with a matrix reason. | | **v0.0.1 language exit** | Every **in-scope** feature-matrix row is `supported` or `dogfooded`, and CI Test262 for the in-scope set has **zero open blockers**. | “Fully compatible” is **not** “looks like a browser” and **not** “runs random npm.” It is **language-level** conformance against the pinned edition. Details: [ES scope](/scripty/v0.0.1-dev/es/scope) and [Test262](/scripty/v0.0.1-dev/es/test262). ## 3. Matrix honesty Every compatibility row uses exactly one of: | Status | Meaning | | ------------- | ------------------------------------------------- | | `unsupported` | Not implemented; must fail closed or be absent | | `partial` | Some paths work; gaps documented | | `supported` | Implemented with automated tests | | `dogfooded` | Supported **and** exercised on a first-party path | Vocabulary reference: [Status vocabulary](/scripty/v0.0.1-dev/reference/status-vocabulary). **Refuse** silent Node/Deno/Bun fallbacks on dogfood paths. **Refuse** “full support” claims until the matrix row says so. ## 4. Exclusive-surface filter (I2 / I3) | Initiative | Include | Exclude | | --------------------- | --------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------- | | **I2 Bun-exclusive** | APIs native to Bun that Node and Deno do **not** ship as first-class runtime APIs | Shared Node modules (`fs`, `http`, …), generic Web APIs present on all three | | **I3 Deno-exclusive** | APIs native to Deno that Bun and Node do **not** ship as first-class runtime APIs | Same shared surface; pure package-manager CLI unless it is a documented runtime API | Exclusivity is by **namespace + shape**, not raw capability. An API is in scope when its specific `Bun.*` / `bun:*` / `Deno.*` surface is not first-class in the other two runtimes — even if a similar capability exists there under a different name (e.g. `Bun.serve` is in I2 although `Deno.serve` exists, because the Bun-shaped API is not first-class in Node or Deno). Rows whose capability is shared but whose shape differs are tracked as `shape-only`. A capability exposed under the **same** first-class API on all three runtimes is not exclusive — track it in shared host / Node-compat work. ## 5. Platform and product locks (unchanged) | Lock | Rule | | -------------------------- | -------------------------------------------------------------------------------------------------------- | | **Linux-only** | Build, CI, docs claims, first-party dogfood — Linux only. No macOS/Windows ports. | | **No webview in scripty** | Desktop UI is host-owned (yappy). Scripty is embed + IPC only. | | **Repo boundary** | This product’s runtime lives in the scripty repo; host products (DX, yappy) stay out. | | **Equal frameworks later** | Next, Nuxt, Nest, Solid remain equal **after** the language gate — not a reason to park ES completeness. | ## 6. Fail closed Outside a `supported` / `dogfooded` row: * Prefer a clear error over a wrong result * Prefer “not implemented” over half-compatible quirks that look like success * Prefer updating the matrix over marketing prose ## 7. Sources of truth Pin external sources in [Sources](/scripty/v0.0.1-dev/reference/sources): * ECMA-262 **edition snapshot** HTML URL + catalog page + pin date (not only the living draft) * Test262 commit / tag used in CI * Bun docs / version for exclusive inventory * Deno docs / version for exclusive inventory When upstream moves, update the pin **and** the matrices in the same change set. ## Related topics - [Initiatives](/scripty/v0.0.1-dev/initiatives.md) - [I3 — Deno-exclusive surface](/scripty/v0.0.1-dev/deno-exclusive/index.md) - [Sources and pins](/scripty/v0.0.1-dev/reference/sources.md) - [Pre-v0.0.1 program](/scripty/v0.0.1-dev/index.md) - [I2 — Bun-exclusive surface](/scripty/v0.0.1-dev/bun-exclusive/index.md)