prometeu-runtime/docs/runtime/specs/15-asset-management.md

Asset Management

Domain: asset runtime surface Function: normative

This chapter defines the runtime-facing asset model of PROMETEU.

1 Scope

PROMETEU asset management is bank-centric.

Assets are:

• cold bytes stored in the cartridge;
• described by cartridge metadata;
• materialized into host-managed banks;
• separate from VM heap ownership.

This chapter describes the runtime contract currently visible in the codebase. It is not a full tooling pipeline specification.

2 Core Principles

1. asset residency is explicit;
2. asset memory belongs to the machine, not to the VM heap;
3. banks and slots are hardware/runtime concepts;
4. loading and activation are explicit operations;
5. asset memory does not participate in GC.

3 Cartridge Asset Artifact

The runtime currently consumes one primary cartridge asset artifact:

• assets.pa: autocontained asset artifact.

assets.pa carries, inside the same binary:

• fixed binary prelude;
• JSON header;
• payload bytes.

The JSON header carries:

• asset_table: metadata entries describing asset content;
• preload: optional initial residency requests consumed during cartridge initialization.

This chapter describes the runtime-facing asset contract. It does not define the Studio packer workflow or the shipper pipeline that publishes the cartridge.

3.1 assets.pa v1 envelope

assets.pa v1 is structured as:

[fixed binary prelude]
[json header]
[binary payload region]

The fixed binary prelude contains, at minimum:

• magic
• schema_version
• header_len
• payload_offset

It may additionally include:

• flags
• reserved
• header_checksum

3.2 Header and payload contract

The runtime loads:

• asset_table from the JSON header and keeps it live during cartridge execution;
• preload from the JSON header and consumes it only during boot.

Payload bytes are addressed from the payload region using offsets relative to payload_offset, not relative to the start of the whole file.

4 Asset Table

Current runtime-facing asset metadata includes:

AssetEntry {
  asset_id
  asset_name
  bank_type
  offset
  size
  decoded_size
  codec
  metadata
}

This table describes content identity and storage layout, not live residency.

offset is relative to the start of the payload region inside assets.pa.

5 Banks and Slots

The current runtime exposes bank types:

• TILES
• SOUNDS

Assets are loaded into explicit slots identified by bank context plus index.

Conceptual slot reference:

SlotRef { bank_type, index }

This prevents ambiguity between graphics and audio residency.

6 Load Lifecycle

The runtime asset manager exposes a staged lifecycle:

• PENDING
• LOADING
• READY
• COMMITTED
• CANCELED
• ERROR

High-level flow:

1. request load of an asset into a slot;
2. resolve the asset entry from live asset_table;
3. open the payload slice in assets.pa;
4. perform read/decode/materialization work;
5. mark the load READY;
6. explicitly commit;
7. activate the resident asset in the slot.

The canonical payload paths are:

• ROM -> open_slice -> CODEX/decode -> Bank
• ROM -> open_slice -> temporary in-memory blob -> CODEX/decode -> Bank

open_slice is the runtime-facing concept for opening a limited view over a payload slice. The runtime must not require the whole assets.pa payload to remain resident in RAM as its baseline operating mode.

OP_MODE selects between direct slice consumption and temporary materialization in memory.

For v1:

• OP_MODE is derived from codec/CODEX;
• explicit per-asset hinting is not part of the baseline contract.

The runtime does not treat asset installation as implicit side effect.

7 Residency and Ownership

Asset banks are host/runtime-owned memory.

Therefore:

• VM heap does not own asset residency;
• GC does not scan asset bank memory;
• shutting down a cartridge can release bank residency independently of VM heap behavior.
• the runtime must not keep the full assets.pa payload resident in RAM as a baseline requirement.

8 Bank Telemetry

The runtime surfaces bank and slot statistics such as:

• total bytes;
• used bytes;
• free bytes;
• inflight bytes;
• slot occupancy;
• resident asset identity per slot.

These metrics support debugging, telemetry, and certification-oriented inspection.

9 Preload

preload is stored in the JSON header of assets.pa.

These preload entries are consumed during cartridge initialization so the asset manager can establish initial residency before normal execution flow.

Lifecycle rule:

• preload is boot-time input only;
• it does not need to remain live after initialization completes.

10 Relationship to Other Specs

• 13-cartridge.md defines the cartridge package and the requirement that assets.pa carries its own asset header.
• 16-host-abi-and-syscalls.md defines the syscall boundary used to manipulate assets.
• 03-memory-stack-heap-and-allocation.md defines the distinction between VM heap memory and host-owned memory.

11 Syscall Surface and Status Policy

asset follows status-first policy.

Fault boundary:

• Trap: structural ABI misuse (type/arity/capability/shape mismatch);
• status: operational failure;
• Panic: internal invariant break only.

11.1 MVP syscall shape

• asset.load(name, kind, slot) -> (status:int, handle:int)
• asset.status(handle) -> status:int
• asset.commit(handle) -> status:int
• asset.cancel(handle) -> status:int

Rules:

• handle is valid only when load status is OK;
• failed load returns handle = 0;
• commit and cancel must not be silent no-op for unknown/invalid handle state.
• slot validation, kind mismatch, and residency/lifecycle rejection remain in asset status space and are not delegated to bank.

11.2 Minimum status tables

asset.load request statuses:

• 0 = OK
• 3 = ASSET_NOT_FOUND
• 4 = SLOT_KIND_MISMATCH
• 5 = SLOT_INDEX_INVALID
• 6 = BACKEND_ERROR

asset.status lifecycle statuses:

• 0 = PENDING
• 1 = LOADING
• 2 = READY
• 3 = COMMITTED
• 4 = CANCELED
• 5 = ERROR
• 6 = UNKNOWN_HANDLE

asset.commit and asset.cancel operation statuses:

• 0 = OK
• 1 = UNKNOWN_HANDLE
• 2 = INVALID_STATE