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R02 · Artifact architecture

The replay protocol must not be the demo protocol.

Valve can change demo framing, protobuf messages, serializers, string tables, user commands, or entity rules. The browser should not need to know. It consumes a stable Subticked replay contract.

Non-negotiable architecture

The browser is not the parser.

Original demos remain private on server infrastructure. Dedicated parser compute produces a normalized replay artifact. The browser receives only validated, versioned, signed output designed for visualization.

0 bytes parser code in the client0 bytes raw demo from replay endpoints100% artifact identity and provenance

Artifact family

One replay is a manifest plus independently useful objects.

ReplayArtifact/
  manifest.jcs.json
  manifest.sig
  index.pb
  segments/core/000000.pb
  overlays/visibility/...
  overlays/research/...
  map-pack -> content-addressed reference

The small canonical manifest is signed. Dense tracks live in compact binary chunks. Optional overlays are independently fetched so normal playback does not pay for every research model.

Segments

Seek by object boundary, not by replaying the match.

Each temporal segment begins with a complete normalized keyframe and contains ordered deltas and events. Seeking restores the keyframe and applies changes through the target coordinate. Backward seek is reconstruction, not reverse simulation.

Integrity

Authorization and artifact authenticity solve different problems.

A short-lived capability permits a browser to fetch an artifact. A manifest signature proves which publication pipeline produced the bytes. Per-object hashes bind every chunk and map pack. Browser resource ceilings remain mandatory even after signature verification.

Evolution

Migrate on the server.

Parser build, artifact compiler, replay schema, map pack, and analysis model have separate identities. Older replay artifacts can be recompiled server-side. The browser supports a bounded schema window instead of accumulating generations of Source 2 compatibility logic.

Boundary

The browser may decode the Subticked artifact schema. That is not permission to include `.dem` framing, Source 2 protobuf descriptors, field paths, PacketEntities, user-command grammar, or parser profiles.