Worker Self-reports Snapshot Compatibility #2348

service WorkerService {
  rpc Register(RegisterRequest) returns (RegisterResponse);
}

message RegisterRequest {
  // +k8s:required
  ObjectRef worker = 1;

  // +k8s:required
  WorkerResources capacity = 2;

  // Runtime that new and cold-booted actors start under.
  // Snapshots matching default_runtime can also warm-boot on this worker.
  // +k8s:required
  SandboxRuntime default_runtime = 3;

  // Additional runtimes (excluding default_runtime) that this worker can
  // restore snapshots from right now.
  // +k8s:optional
  // +k8s:maxItems=32
  repeated SandboxRuntime restorable_runtimes = 4;
}

message SandboxRuntime {
  // e.g. "gvisor", "microvm"
  // +k8s:required
  string sandbox_class = 1;

  // SandboxConfig or version name (e.g. "gvisor-2"), informational only,
  // never used during scheduling.
  // +k8s:optional
  string name = 2;

  // Primary compatibility version stamped onto an actor's snapshot when a
  // checkpoint is taken on this runtime. Snapshots matching `version` can
  // warm-boot on this runtime.
  // +k8s:required
  VersionedSandboxCompat version = 3;

  // [Post-GA] Additional compatibility versions (excluding `version`) that can
  // warm-boot directly onto this runtime (either an older schema version like
  // "v1", or an older runtime asset digest whose checkpoints this binary can
  // restore).
  // During scheduling, a snapshot can warm-boot on this runtime if its version
  // matches either `version` or one of `compatible_versions`.
  // When the actor suspends again, its new snapshot is stamped with the primary `version`.
  // +k8s:optional
  // repeated VersionedSandboxCompat compatible_versions = 4;
}

message VersionedSandboxCompat {
  // Compatibility schema version (e.g. "v1") defining which runtime and
  // hardware attributes are recorded and how they are computed.
  // +k8s:required
  string version = 1;

  // Key-value compatibility attributes defined by this schema version, covering
  // both runtime assets (e.g. "gvisor_asset_hash") and effective guest hardware
  // features after masking (e.g. "architecture", "cpu_features").
  // Matched by exact equality of all keys and values within the same version.
  // +k8s:required
  repeated AttributeEntry attributes = 2;
}

message AttributeEntry {
  string key = 1;
  string value = 2;
}