Files
DarkRoom/CONTRIBUTING.md
T
dtourolleandClaude Opus 5 95847e3a31 Say which channels v1 ships through, and that the Flatpak cannot reach a library
NFR-COMPAT-2 asks for the v1 channels to be stated, and says why in its own
second sentence: the channel decision and the storage design are coupled. There
was nowhere that statement lived. packaging/ held a PKGBUILD and a desktop
entry, which is a recipe rather than a decision, and the coupling the
requirement points at was therefore invisible.

docs/distribution.md states five channels and, more usefully, which two of them
exist only as promises. It also records what every channel has to get right
independently of format — the one identifier that appears in four places, the
metainfo, Vulkan being a requirement rather than a preference while NFR-R8 is
open, a secrets daemon being optional rather than required, and the LFS pointer
check that stops a package shipping 130 bytes where an 11 MB model should be.

§4 is the part worth reading. Preparing a Flatpak is what surfaced that
FR-PLAT-LIN-3 is not satisfied and cannot be satisfied by packaging alone: a
folder library is chosen by typing an absolute path into an EndpointOnly field
that checks it with std::fs, and nothing in the tree calls the FileChooser
portal. Inside a sandbox that path does not exist, so the launch screen refuses
it. Import fails one step earlier, because a sandboxed process reads its own
mount namespace and a card mounted on the host is not in it.

That is written down rather than fixed with --filesystem=host, and the argument
for not fixing it that way is §2: the Arch package and an AppImage both hand the
application the same unrestricted process the developer runs it in, so Flatpak
is the only Linux channel that tests whether a design assumed unrestricted
access. Granting the permission removes the only reason to ship it.

The reverse coupling on Android is recorded too. NFR-COMPAT-2 says Play
distribution is what makes ARCH §6.9 binding; §6.9 is verified rather than
assumed, so SAF is already unconditional and a sideloaded build would gain
nothing by asking for more. Play is deferred over the GPLv3 question, which is
a licence-reading exercise and blocks nothing in the storage design.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-29 20:18:20 +02:00

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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`](core/dr-pipeline/ops/README.md) and
copy [`exposure.yaml`](core/dr-pipeline/ops/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:
```bash
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:
```bash
sudo apt-get install pkg-config libfontconfig1-dev libxkbcommon-dev
```
**Then:**
```bash
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`](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:
```bash
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`](docs/requirements.md) is the register of record.
[`traceability.md`](docs/traceability.md) is generated from `TRACES:` tags in
the source and must never be hand-edited:
```rust
// 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:
```bash
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 a `presentation:` hint in the declaration and a `WidgetKind`,
not a branch in `develop.rs`.
- **The operation schema rejects ambiguity at build time**: a duplicate
`order:`, a filename disagreeing with its `id:`, 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`](core/dr-pipeline/ops/README.md) | Adding or changing a develop operation — start here regardless |
| [`docs/architecture.md`](docs/architecture.md) | Anything touching the render path, catalog or sync |
| [`docs/code-health.md`](docs/code-health.md) | Deciding what to work on; grades each seam by what it costs |
| [`docs/technical-debt.md`](docs/technical-debt.md) | Something looks wrong — check it was not chosen |
| [`docs/distribution.md`](docs/distribution.md) | Packaging a build, or adding a permission to one |
| [`docs/requirements.md`](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.