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Capsules

A Capsule is Murmur's primary execution abstraction.

A capsule launches from a manifest, installs its declared artifacts, executes inside a constrained environment, writes outputs, and exits.

Isolation model

Murmur uses the WASM Component Model as the primary execution boundary:

  • WASM components run in a sandboxed runtime
  • WASI capabilities explicitly control filesystem and network access
  • Manifest capability grants are part of the security policy

For tool artifacts, Murmur supports both:

  • WASM tools (preferred, stronger isolation)
  • Native tools (compatibility path, process-level boundary)

Lifecycle

Typical lifecycle:

  1. Launch capsule
  2. Read manifest
  3. Resolve and install artifacts
  4. Execute workload
  5. Write outputs/logs
  6. Exit

Capsules are designed to be fast-starting and horizontally scalable.

Why WASM

WASM enables consistent execution contracts and explicit capability boundaries, while still allowing portable packaging and composable interfaces between runtime components.