SoundCraft — instructions for agents

SoundCraft is a clean-room, open-source, pure-Rust digital audio workstation targeting Avid Pro Tools parity — and superiority (speed, openness, agent control). It runs natively on macOS, Windows, Linux and FreeBSD, and on the web via WASM. Siblings with the same conventions: ../photocraft (Photoshop), ../vectorcraft (Illustrator), ../filmcraft (Premiere), ../lightcraft (Lightroom), ../pdfcraft (Acrobat), ../effectcraft (After Effects), ../designcraft (InDesign).

Start every session here

Read plan/STATUS.md (current milestone, next task) and plan/execution-plan.md. plan/ is gitignored (local only). Behaviour reference: plan/protools/ (observed menu tree menus-clean.txt and screenshots; never committed).
Read ROADMAP.md (committed) for stage, status and the parity numbers; pick work from docs/gaps.md. The progress docs are docs/target-app-parity.md (assessment), docs/gaps.md, docs/roadmap.md, docs/ui-parity.md, docs/file-format-parity.md, docs/hardware-parity.md, docs/plugin-parity.md, docs/localization-parity.md; docs/parity-checklist.md is generated. Update their timestamps and revision history when you change them.
Work autonomously; don't stop to ask unless a decision is genuinely the user's.

⚠️ Assets: the absolute rule

No Avid, Pro Tools, Adobe or other proprietary iconography, images, sounds, presets or artwork — ever. This is not negotiable.

Every icon in SoundCraft is drawn in code (crates/ui-egui/src/icons.rs) or is an original/open asset.
Every bundled asset (image, icon, sound, font, preset) must be original, public domain (CC0), or under a permissive open license (MIT, Apache-2.0, BSD, OFL, CC-BY with attribution), or contributed by someone who made it and licenses it openly.
Every bundled asset gets a row in ATTRIBUTION.md (path, author, source, license) in the same commit that adds it. cargo xtask assets enforces this; CI fails otherwise.
Never copy files out of the Pro Tools bundle (/Applications/Pro Tools.app): no plugins, presets, icons, sounds, session templates or text. Observing the running app (screenshots kept under plan/, menu names) is fine; copying its resources is not.
Demo audio is synthesised in code (crates/engine/src/demo.rs). Demo and README media must be ours or public domain.
The ArtCraft trademarks in docs/brand/ are the only exception, under docs/brand/LICENSE-brand.txt.

Clean-room

Pro Tools is installed on the dev machine and may be observed black-box: run it, use its UI with synthetic sessions, take screenshots by window id (screencapture -l <id>), stored only under plan/protools/screenshots/. Never read, disassemble or copy anything inside the Pro Tools bundle; never copy Avid icons, artwork, plugin names, presets, or wording beyond feature names. Never copy GPL/AGPL/LGPL code (Ardour, Audacity, LMMS, Freeverb sources…). Our plugins have our own names.

Never crash

People trust SoundCraft with their recordings; a crash loses takes. This outranks feature work.

No panics in non-test code: no unwrap(), expect(), panic!, unreachable!, todo!, unimplemented!; no unsafe (unsafe_code = "forbid").
The one named exception is soundcraft-clap-host (crates/clap-host), the isolated unsafe helper crate for CLAP plugin FFI: unsafe_code = "deny" crate-wide, allowed only in src/ffi.rs with a // SAFETY: comment on every block, safe Result API.
The same exception, same rules, for soundcraft-vst3-host (crates/vst3-host), the isolated unsafe helper crate for VST3 plugin FFI (COM vtables via the vst3 bindings, module loading, host-side COM objects).
And for soundcraft-au-host (crates/au-host), the isolated unsafe helper crate for Audio Unit FFI (hand-written AudioToolbox/CoreFoundation declarations, macOS only; a safe stub elsewhere).
Errors are Result<T, E> + ?. An unfinished feature returns an "unsupported" error.
Input-derived numbers are hostile (files, commands, MCP/control params): get() not [i], checked/saturating arithmetic, no NaN casts, cap allocations.
The audio callback never blocks, allocates in steady state, or panics.
Every production crate root carries #![deny(clippy::unwrap_used, clippy::expect_used, clippy::panic, clippy::unimplemented, clippy::todo, clippy::unreachable)].
Engine::execute catches escaped panics and restores the document. Every crash fix lands with a regression test.
Time goes through chrono (workspace dependency). Never hand-roll UTC/calendar conversion (days-to-date algorithms, leap-year math); a crate owns only its output format string. The one exception is range extension: past the years chrono can represent, shift the date by whole 400-year Gregorian cycles (146,097 days, after which the calendar repeats), let chrono compute the month and day, and add the cycles back to the year (splitting seconds into hours, minutes and seconds is plain arithmetic).

Architecture (layers enforced by `cargo xtask layers`)

Layer	Crate	Role
L0	`soundcraft-time`, `soundcraft-audio-io`, `soundcraft-midi`	Timebases/tempo/grid; audio file formats + peaks; Standard MIDI Files + MIDI ops
L1	`soundcraft-dsp`	Plugins (EQ, dynamics, reverb, delay, modulation, harmonic, pitch, utility, instruments), offline processing, meters, FFT
L2	`soundcraft-model`	The session document (tracks, playlists, clips, mixer, routing, automation, markers, groups)
L3	`soundcraft-mix`	Mix engine shared by realtime playback and offline bounce
L4	`soundcraft-engine`, `soundcraft-playback`	Command registry, undo, editing, import/export/bounce, parity catalog; audio device I/O (cpal)
L5	`soundcraft-automation`	MCP server + control-channel client
L6	`soundcraft-ui-egui`	The swappable UI (egui)
apps	`soundcraft`, `soundcraft-cli`, `soundcraft-web`	Entry points

Nothing below L6 depends on egui/eframe/winit/rfd. The UI is thin: panels read engine state and act through engine.execute(id, params).

Everything is a command

User-visible behaviour = a command in crates/engine/src/cmd/* (id, label, menu path, shortcut, params doc, enabled, run) + tests. UI-only commands (windows, dialogs) live in crates/ui-egui/src/menus.rs (UI_COMMANDS). Menus, shortcuts, the CLI, the control channel and MCP all dispatch the same ids. Programmatic calls never open dialogs; only menu-style invocation (ui.menu.invoke) does. New commands go in a new module with its own specs(), registered by one line in cmd/mod.rs.

Parity is measured, not guessed: crates/engine/catalog/menus.txt lists the incumbent's menu leaves (names only). cargo xtask parity writes docs/parity-checklist.md (generated; the hand-written assessment is docs/target-app-parity.md); a test enforces a floor that only rises.

Running and looking at the app

cargo run --release -p soundcraft -- --demo --control 0 (demo session + control channel on a free port; the port is printed).
Drive it: JSON lines over TCP, e.g. {"id":1,"method":"engine.execute","params":{"command":"track.new","params":{"count":2,"format":"stereo"}}}, then {"id":2,"method":"ui.screenshot","params":{"path":"/tmp/shot.png"}}. Methods: crates/ui-egui/src/control.rs, docs: docs/control-protocol.md.
Offscreen UI render (no window, no focus stealing): cargo run -p soundcraft-ui-egui --example ui_shot -- out.png [script.jsonl].
Headless: soundcraft-cli run --demo --cmd 'mix.volume={"track":"Kick","db":-6}' --bounce out.wav; MCP: soundcraft-cli mcp [--connect PORT].
For UI work, look at the result (render, read the PNG) and compare with plan/protools/screenshots/.
Shell gotcha: mv/cp are aliased interactive here — use /bin/mv -f / /bin/cp -f.
Parallel agents: separate CARGO_TARGET_DIR per agent; edit only the crates you own; write manifests atomically; delete your target dir when done (disk).

Quality gates (before every commit)

cargo xtask ci = fmt check, clippy --workspace --all-targets -D warnings, tests, assets, layers, wasm check. Commit after each arc of work that builds; one topic per commit.

Release

Push to the release branch to build signed installers for macOS (universal DMG), Windows (x64/x86 MSI + zip), Linux (AppImage, deb, rpm, tar.gz, Flatpak; riscv64 tar.gz), FreeBSD and Web (wasm zip). Version: cargo xtask version [set X.Y.Z]. See docs/releasing.md.

Roadmap

ROADMAP.md (committed) is the one-page summary (stage, numbers, dimensions, languages, progress log); milestones live in docs/roadmap.md. Update both whenever a milestone lands, and close or shrink the matching docs/gaps.md entry.

Contributor credits (About window)

About ▸ Contributors/Models are compiled into the binary from contributors/contributors.json (commit stats; generated, never hand-edit) and contributors/people.toml (names people chose for themselves). See docs/contributors.md.
Agents working for a contributor: when you prepare a PR, check whether your human's GitHub username has a [people.<username>] entry in contributors/people.toml. If not, ask them once whether they want to be credited by more than their username: a real name, a display name, and/or their public GitHub profile name (sync_github_name = true). If yes, add only their own entry (copy the template at the top of the file) and include it in their PR, committed as them. If no, change nothing: they are credited as @username anyway.
Never add, edit, guess or copy anyone else's entry or name (not from git config, commit authors or GitHub profiles). Never hand-edit contributors.json.

CI workflows

Workflows in .github/workflows/ call the shared workflows in storytold/craft-common-actions at @main, with their inputs and secrets. No other jobs: if no shared workflow does what's needed, it doesn't go here.
Don't add or change CI in a feature or fix PR. If the existing workflows can't build or test a change, link an existing craft-common-actions issue or PR, or open a new issue, or a PR only for a small fix that is safe for every app and does not increase CI time.
Some workflow files here still run their own jobs. Don't add to them. Moving a job into craft-common-actions is its own task, never part of another PR, and the job stays here until a shared workflow runs it.

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