dtourolleandClaude Opus 5
617262b4da
There was none. 14 documents, 177 numbered requirements, and all of it written for someone who has already decided to work on this — nothing that tells a newcomer which door is unlocked, what a first build needs, or why it takes so long. CONTRIBUTING.md points the first door at the operation format, because "add a develop node" is a genuinely one-file contribution and the best first experience this codebase can offer: no Rust, no shader edit, no UI change, and its tests declared in the same file. It teaches the architecture's central idea on the way through, which is why the invariant test added in the previous commit is named there rather than left to be discovered. Three things that were folklore are now written down: Git LFS is a prerequisite, the first build resolves 826 crates and is not hanging, and Slint needs pkg-config, libfontconfig1-dev and libxkbcommon-dev. The LFS one proved itself while writing this — a fresh worktree hit exactly the failure `dr-segment`'s build script is written to catch, which is the argument for saying so before it happens rather than after. rust-toolchain.toml pins 1.92.0 because `build-and-test.yml` already does and says why: a floating toolchain turns an unrelated push into a mystery failure. The two checks that gate every push are the two most sensitive to compiler version — rustfmt's output changes between releases, so a contributor on a newer stable can produce a diff nobody wrote on a line nobody touched, and `clippy -D warnings` is the same story with new lints. `rust-version = "1.92"` in the manifest stays where it is; it is a minimum, and this is the upper bound it cannot express. Also states the convention the tooling cannot enforce, from code-health.md CH-4: close a requirement with a test that would fail if the behaviour were removed. Coverage that moves slowly and means something beats coverage that moves quickly. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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Contributing to DarkRoom
There is a lot of documentation here — 14 documents and 177 numbered requirements — and almost all of it is written for someone who has already decided to work on this. This file is the other thing: how to get a first change landed without reading any of it.
The shortest useful contribution
A develop operation is one file. Not one file plus a registration, plus a shader edit, plus a control in the UI — one file:
core/dr-pipeline/ops/split_toning.yaml
build.rs finds it with read_dir, compiles it into Rust implementing
Operation, and from there it is indistinguishable from a hand-written node.
It arrives with controls built from its declared parameter kinds, a place in
the chain from order:, a place in the panel from attributes:, sidecar
persistence, and its own tests — which are declared in the same file and run
under cargo test.
Read core/dr-pipeline/ops/README.md and
copy exposure.yaml. Split toning,
colour zones, selective colour and channel-mixer variants are all pure point
operations, which means all of them are declarations rather than code.
If you want to understand one thing about the architecture before starting,
make it this: the core describes its capabilities and the interface composes
them. No code in ui/ names an operation, and a test enforces that
(ui/dr-ui/tests/ui_names_no_operation.rs). It is why your node needs no UI
change.
Getting it to build
Git LFS is required. Model weights are stored in LFS, and a clone made without it leaves a ~130-byte text pointer where an 11 MB model should be:
git lfs install && git lfs pull
Forget this and dr-segment's build script stops with an instruction rather
than embedding the pointer and failing at inference time — but it is easier to
run the two commands now.
The toolchain pins itself. rust-toolchain.toml selects 1.92.0 and rustup
fetches it on first use. Do not override it; cargo fmt and clippy are both
version-sensitive and CI runs exactly this version.
System packages. Slint and winit need these at build time. On Debian or Ubuntu:
sudo apt-get install pkg-config libfontconfig1-dev libxkbcommon-dev
Then:
cargo run -p darkroom-desktop
The first build resolves 826 crates and takes a while — on a laptop, long enough to look like a hang. It is not one.
Android is a containerised toolchain and is not needed for most work; see
docker/android/README.md if you get there.
What CI will check
All four of these run on every push, so run them before you send anything:
cargo fmt --all -- --check
cargo clippy --workspace --all-targets -- -D warnings
cargo test --workspace
cargo build --workspace --release
GPU tests skip themselves where there is no adapter rather than failing — a test that cannot run is not evidence either way — so a green run on a machine without a GPU is expected, and does not mean the GPU paths were exercised.
Requirements and traceability
requirements.md is the register of record.
traceability.md is generated from TRACES: tags in
the source and must never be hand-edited:
// TRACES: FR-DEV-3a | FR-DEV-3c
Tags are read from .rs, .slint, .wgsl and .yaml — the last so a
declared operation can record the requirement it satisfies, since the Rust it
generates lands in OUT_DIR and is not scanned.
A pre-commit hook regenerates the matrix and stages it whenever you touch something that can carry a tag, so you should not have to think about it. If you do need to run it by hand:
cargo run -p traceability -- report
Note that it tracks line numbers, so a change that only moves code still moves the matrix. Never regenerate it with a stale prebuilt binary.
One convention that the tooling cannot enforce. A tag proves that a tag
exists, not that the code under it does the thing — docs/code-health.md
CH-4 has the details, and two requirements currently read as covered on the
strength of plumbing a future feature would use. So: close a requirement
with a test that would fail if the behaviour were removed. Coverage that
moves slowly and means something beats coverage that moves quickly.
Two invariants the build defends
Worth knowing before you trip one, because both failures name a requirement rather than a line:
- No operation may be named in
ui/(FR-DEV-3a). Special-casing one operation in the panel to fix a layout problem is how a generated interface stops being generated. If a node needs presentation the panel cannot give it, the answer is apresentation:hint in the declaration and aWidgetKind, not a branch indevelop.rs. - The operation schema rejects ambiguity at build time: a duplicate
order:, a filename disagreeing with itsid:, a default outside its own range, an expression naming something that is not a parameter. Each error names the key you got wrong and exits rather than panicking.
Commit messages
Imperative subject describing the change from the reader's side — "Offer the merge when two people turn out to share a name", not "fix: merge dialog". No conventional-commits prefixes.
The body is where the reasoning goes, and it is expected to be substantial when the change is. This codebase records why far more than most, in commits and in comments alike, and that is the single habit most worth adopting: the constraint you worked around is invisible to whoever reads the diff next.
One commit per change. If you fixed two things, that is two commits.
Where to read next, in order
| Document | Read it when |
|---|---|
core/dr-pipeline/ops/README.md |
Adding or changing a develop operation — start here regardless |
docs/architecture.md |
Anything touching the render path, catalog or sync |
docs/code-health.md |
Deciding what to work on; grades each seam by what it costs |
docs/technical-debt.md |
Something looks wrong — check it was not chosen |
docs/requirements.md |
Reference, not reading |
technical-debt.md is the one to check before "fixing" anything surprising.
It records compromises that were deliberate, each with the reasoning and a
falsifiable condition for when it stops being one — the point being that you
can tell a constraint from an accident without asking.
Licence
GPL-3.0-or-later. By contributing you agree your work is licensed the same way.