Authoring an Audio Test Case

An audio asset-generation test case asks a model to author one short game-audio clip — a sound effect or a snatch of music — through an audio binary, one recorded operation at a time, to match a written brief. Like every asset-generation case there is no target clip: the model is given a precise description of the sound and the freedom to build something that matches it, so the case rewards sound-design reasoning rather than the faithful reproduction of a supplied recording. It plays out entirely in the ear of a reviewer — the model cannot hear its own output, so the binary renders a waveform + spectrogram (and, for music, a piano-roll) it reads to see its progress. Authoring a case is mostly writing a precise, self-contained brief.

Manifests is the authoritative schema for the [audio] table and its rules; the Audio binaries page documents exactly how each tool behaves (the modular synth graph, the sample-library mixer, the note-sequencer over an instrument bank); the Overview says why the recorded actions — not the .wav on disk — are the output; and Evaluation covers how a clip is validated and reviewed. Read those first. This guide is self-contained; you do not need anything beyond the pages it links.

Drawing a 2D sprite, sculpting a 3D voxel or mesh, or building a playable game are different kinds (or a different test type) with their own manifests; see Authoring an Asset-Generation Test Case and Authoring an End-to-End Test Case.

A case is exactly one of three kinds, chosen by the manifest’s asset_kind — a version-level choice, not a variant axis:

sfx-synth — synthesize a sound effect from a modular synth graph alone (oscillators, noise, envelopes, filters, FM). It names no sample pack or bank: the sound is built from nothing but DSP. The worked example is spectra-laser (a synthesized laser-fire blip).
sfx-sample — layer a sound effect over a baked sample library, the game-audio-DAW tier: select, layer, time, pitch, and process recorded library clips (with synth voices for glue). It names a sample_pack = "name@version". The worked example is thunderhead-broadside (a layered naval-cannon report over the combat-core pack).
music — sequence a short piece as notes on instrument tracks over a baked instrument bank, and emit a portable .mid beside the .wav. It names an instrument_bank = "name@version". The worked example is thunderhead-theme (a short military battle theme over the gm-lite bank).

Read the worked example matching the kind you are authoring alongside this guide; a new case should look like it.

What an audio case is, and what gets seeded

A version lives under test-cases/<type>/<difficulty>/<slug>/<version>/. Versioning is per-case and immutable: once a run references a version, that version is frozen. Revise by adding a new version, never by editing a published one.

test-cases/<type>/<difficulty>/<slug>/<version>/
  test-case.toml         # manifest: type, asset_kind, audio, tool, output, the overall domain
  variants/              # one standalone TOML file per variant (listed in `variants`)
  prompt.hbs             # rendered per run into the model's instruction (NOT seeded)
  description.md         # site-facing prose (NOT seeded)
  README.md              # human overview (NOT seeded)
  specs/brief.md         # the brief: what to build + how the tool behaves — SEEDED

A run receives only the seeded files: the selected variant’s brief. There is no target clip — the model builds to match the brief, not to copy a supplied recording. It also gets the audio binary (sfx-synth, sfx-sample, or music) on its PATH, whose --help is the operations contract — no operations schema is seeded — plus a pre-seeded config next to the workspace (sfx-synth.config.json / sfx-sample.config.json / music.config.json) carrying the [audio] format and the log/preview/output paths, so no operation needs those flags. For an sfx-sample or music case the run is scheduled onto the image carrying the named pack or bank, so the library the model browses with list-samples (or the instruments it names with define-track) is already present. Everything marked NOT seeded is authoring- or site-side only.

Unlike the pixel tools, the audio binaries do not re-render after every call — rendering is a separate, on-request render step that mixes the recorded ops down to the .wav and draws the preview. The render is deterministic (synthesis noise draws from a fixed seed; sample mixing is a pure function of the placed layers), so replaying the recorded ops reproduces the same .wav — the recorded operation log is the authoritative output. There is no cheat-divergence check for audio (the emitted waveform is what is scored); the only contract check is that the clip is well-formed, within the declared format, no longer than max_duration_ms, and not silent.

Procedure

1. Choose the kind, and what naming a pack or bank implies

Pick the asset_kind by what skill you want to measure:

sfx-synth measures whether a model can build a sound from oscillators and noise alone — the rawest DSP tier. Name it when the sound is fundamentally synthetic (a laser, a UI blip, a sci-fi pulse) and you want no recorded material in play. It names neither a pack nor a bank.
sfx-sample measures whether a model can select, layer, time, pitch, and process library clips the way a game-audio DAW does — the tier the hard 3D cases’ weapon, naval, and footstep SFX use. It is a superset of sfx-synth (it still carries every synth voice, for glue), and it must name a sample_pack = "name@version".
music measures composition — pitches, beats, and durations on instrument tracks — the easiest of the three to author because the model works in the symbolic layer rather than shaping raw DSP. It must name an instrument_bank = "name@version" and emits a portable .mid beside the .wav.

A named pack or bank is a name@version baked into the run-container image, never a path in this repo. The audio files are not committed here; a run container is offline, so the palette is baked into the sfx-sample / music image at build time and the case’s manifest simply names which baked palette it expects. The run is then scheduled onto the matching image. The currently-published palettes a case can name today are combat-core (a sample pack) and gm-lite (an instrument bank). If you need a palette that does not exist yet, publish it first — see Publishing an Audio Sample Pack — and pin its name@version here. A sample_pack/instrument_bank value that is not pinned is a build error, not a silent fallback, so a case can only name a palette that has been published.

Pick a catalog slug for the lineage (e.g. spectra-laser) and a version (vX.Y.Z).

2. Write the brief

Write specs/brief.md — a single self-contained file. Because the reviewer hears the finished clip against this text, describe the sound, not the operations:

the sound’s character and role — what it is and where a game uses it (a fighter’s primary laser fire; a battleship’s main-gun broadside; a short battle theme that plays over a briefing screen), in concrete sonic terms — bright vs. dark, tight vs. booming, its pitch register, its grit or cleanliness;
its envelope and timing within max_duration_ms — the shape over time: a sharp transient attack, how long the body sustains, the decay and the tail. For music, the tempo, meter, and roughly how many bars it runs. State it so the whole clip fits inside the cap you set;
the layers, synth graph, or note material — conceptually — for sfx-synth, the voices that stack (a low boom body, a noise crack, a pitch-swept zap); for sfx-sample, the kind of layers to composite from the pack (a deep cannon blast, a metal-debris tail, a synth sub for weight) — describe the ingredients, not the exact sample names, since the model must reason over the library itself; for music, the instruments, the melodic/harmonic idea, and the feel;
mono or stereo — and, if stereo matters, how the image should be placed;
for sfx-sample / music, which pack or bank it draws from — name it (e.g. “layer from the combat-core sample pack” / “voiced from the gm-lite instrument bank”) so the brief matches the manifest, and remind the model it browses the library by metadata (list-samples / sample-info) because it cannot audition audio.

Also state how the tool behaves: that the audio binary is the only way to shape sound, that it renders only on the render command (the model must call it to see its waveform/spectrogram progress), that the recorded operations are the output, and that it should read the binary’s --help for the exact operation vocabulary.

The same self-containment and precise-values rules as any spec apply: the brief must stand on its own, with no link outside the seeded set, and every audible detail written in real terms. The shared quality directive (the brief is the floor, not the goal — produce the best-sounding clip you can within its constraints) is auto-prepended to every asset-generation prompt at render time, so the brief need not restate it.

3. Write `prompt.hbs`

A short instruction that points the model at the seeded brief, tells it to read the binary’s --help for the operations (and, for a sampled kind, to browse the library with list-samples first), and states the hard requirements: shape sound only through the tool; call render to preview; keep the clip within max_duration_ms; return when finished. The template renders in strict mode, so use only the documented variables — {{variant.slug}} / {{variant.name}} / {{variant.description}} and {{#each specs}}.

4. Write the manifest

Author test-case.toml per the schema:

Metadata — name, difficulty, and tags, all required and site-facing.
type = "asset-generation" — required. Omitting it defaults to end-to-end, which then rejects the tables below.
asset_kind — "sfx-synth", "sfx-sample", or "music".
[audio] — replaces the [canvas]/[voxel] table. It fixes the output format: sample_rate (Hz), channels ("mono" or "stereo"), and max_duration_ms (any positive clip-length cap), all required. An sfx-sample case additionally names sample_pack = "name@version"; a music case names instrument_bank = "name@version"; an sfx-synth case names neither.
[tool] — the binary (matching the kind) and the preview path the binary writes the waveform + spectrogram to on render (a piano-roll as well, for music). No operations schema — the binary’s --help is the contract.
[output] — the actions op log the binary records; this is the authoritative output. Core emits the rendered clip.wav (and, for music, a portable clip.mid) automatically — these are not manifest-declared.
No [model] — an audio case declares none; it authors one clip and is judged subjectively, with no required-animation contract.
variants — an ordered array of paths to standalone variant files under variants/ (the first is the default; at least one is required, usually base). As a root key it must precede the first table header. A variant here varies only the seeded brief (an additive [[spec]]) the model builds toward — a tighter register, a shorter cap, a required technique.
[[domain]] — the single overall scoring domain, and no [[review_item]] checklist: the clip is judged as a whole against its brief, so the reviewer plays it, reads the brief, and gives one rating, which is the run’s rating (see Judged on one overall rating). The domain is reporter-side and not seeded; everything a checklist item would have named belongs in the brief.

There is no [[reference]] (an audio case has no target clip), no [build] table, and no [[check]] — declaring any is rejected.

Two realistic manifests. First, the sfx-synth worked example — a synthesized laser blip, no pack:

slug       = "spectra-laser"
name       = "Spectra Laser"
difficulty = "easy"
tags       = ["asset-generation", "audio", "sfx", "synth"]
type       = "asset-generation"
asset_kind = "sfx-synth"
prompt     = "prompt.hbs"

variants = ["variants/base.toml"]

[audio]
sample_rate     = 44100      # output sample rate in Hz (required)
channels        = "mono"     # "mono" | "stereo" (required)
max_duration_ms = 600        # cap on the rendered clip's length in ms (required, positive)
                             # sfx-synth names NO sample_pack / instrument_bank

[tool]
binary  = "sfx-synth"        # the audio binary for this kind
preview = "waveform.png"     # where the binary writes the waveform + spectrogram on `render`

[output]
actions = "actions.json"     # the recorded op log; clip.wav is emitted automatically by core

# The self-contained brief, seeded for EVERY variant (dest defaults to source).
[[spec]]
source = "specs/brief.md"

[[domain]]
id = "overall"
name = "Overall"
description = "How good the produced asset is overall, judged against the brief."

Second, the sfx-sample worked example — thunderhead-broadside, layered over the combat-core sample pack (a music case is identical in shape but names instrument_bank = "gm-lite@0.1.0" instead of sample_pack, and its preview also carries a piano-roll):

slug       = "thunderhead-broadside"
name       = "Thunderhead Broadside"
difficulty = "hard"
tags       = ["asset-generation", "audio", "sfx", "naval"]
type       = "asset-generation"
asset_kind = "sfx-sample"
prompt     = "prompt.hbs"

variants = ["variants/base.toml"]

[audio]
sample_rate     = 44100          # output sample rate in Hz (required)
channels        = "stereo"       # "mono" | "stereo" (required)
max_duration_ms = 3500           # cap on the rendered clip's length in ms (required, positive)
sample_pack     = "combat-core@0.1.0"  # sfx-sample ONLY: the baked pack (name@version), never a repo path
                                 # (music would name instrument_bank = "gm-lite@0.1.0" instead)

[tool]
binary  = "sfx-sample"           # the audio binary for this kind
preview = "waveform.png"         # where the binary writes the waveform + spectrogram on `render`

[output]
actions = "actions.json"         # the recorded op log; clip.wav is emitted automatically by core

# The self-contained brief, seeded for EVERY variant (dest defaults to source).
[[spec]]
source = "specs/brief.md"

[[domain]]
id = "overall"
name = "Overall"
description = "How good the produced asset is overall, judged against the brief."

Each variants entry points at a standalone file whose top-level keys are the variant’s own fields; the base variant is usually just its slug/name and an empty additive spec = [].

5. Write the non-seeded docs

description.md (site blurb) and README.md (human overview). These never reach a run; keep them honest about what is seeded and which pack or bank the case expects.

Validate your work

There is no separate authoring linter — you validate a case by resolving and seeding it. For every variant:

tcab prompt --test-case <slug> --version <version> --variant <variant>
tcab seed   --test-case <slug> --version <version> --variant <variant>

prompt renders the instruction (catching strict-mode template errors and manifest problems — including a missing [audio] field, a sample_pack on a non-sfx-sample case, an instrument_bank on a non-music case, or a stray [[reference]]/[build]/ [[check]]). seed writes the seeded repository to disk so you can read exactly what the model would receive — the brief plus the seeded audio config — and confirm it is self-contained. If you named a sample_pack or instrument_bank, double-check it is a published, pinned name@version (combat-core / gm-lite today); an unpinned palette is a build error. When the case is ready, exercise it end to end with Run a Test Case.

Next steps

Publishing an Audio Sample Pack — if your case needs a pack or bank that does not exist yet, curate, publish, and pin it before naming it in the manifest.
Reviewing Test Run Results — assess a run of your case, playing the clip against the brief.