Bundle Entry: docs/spec/HOST_RUNTIME_BUNDLE_v0.1.md

Browser Host Runtime v0.1

Status: normative for wasm-host/browser-aligned first-party runtime behavior.

Goal

Define deterministic browser-oriented host capability behavior that can run identically in:

• native host CI/runtime (first-party runtime),
• WASI/wasm-host bridge profile lanes,
• browser wasm execution paths.

Runtime Profile Contract

caps.toml per-op policy supports:

• first_party_profile = "browser" for gfx/window::*, gfx/input::*, gfx/audio::*.

Profile guarantees:

• deterministic event emission driven by effect log ordering,
• no ambient host-time/input dependence outside logged payload/response terms,
• stable backend/adapter identity fields:
  • :backend = "browser-first-party-runtime"
  • :adapter = "browser-host"

Browser ABI Families

Baseline families:

• browser/window::*
  • browser/window::open
  • browser/window::close
  • browser/window::info
• browser/input::*
  • browser/input::poll
• browser/audio::*
  • browser/audio::set-master
  • browser/audio::enqueue
• browser/storage::*
  • browser/storage::get
  • browser/storage::set
  • browser/storage::delete

These ops are first-party deterministic by default and can be explicitly bridge-routed via per-op bridge policy (bridge_cmd or wasi_bridge_profile response mapping).

Determinism + Replay

• First-party browser runtime state is process-local deterministic state (window table, storage map, audio counters).
• run and replay must produce identical value hashes for the same program/log pair.
• WASI bridge-profile responses for browser families must preserve replay hash parity under scripts/check_agent_workflow_runtime_parity.sh.