DarkRoom/docs/outstanding.md

# DarkRoom — Outstanding work

**Status:** Living document · first written 2026-08-29
**Companion to:** [requirements.md §7](requirements.md), [technical-debt.md](technical-debt.md),
[traceability.md](traceability.md)

What is specified and not built, and for each cluster whether that is a decision, a dependency, or a
gap nobody has looked at.

This document exists because [traceability.md](traceability.md) cannot tell those apart. It reports
one number — the share of requirements carrying a `TRACES` tag — and a missing tag means either
"nobody has built this" or "somebody built it and did not say so". Both read the same way in the
summary table, which makes that figure pessimistic *and* uninformative at once: it understates what
works while hiding which of the remainder matters. Eight requirements gained a tag on this branch
because the code already satisfied them and nobody had said so. Everything below is the other kind.

It is also not a plan. [requirements.md §7](requirements.md) records what was deferred deliberately
and needs no argument; this records what is still nominally in scope, so that the distance between
the register and the binary is visible rather than something a reader has to reconstruct from a
percentage. Where the honest answer is "this requirement should be amended rather than met", it says
so — an unbuilt requirement that nobody intends to build is worse than a deferred one, because it
keeps costing attention.

**Several entries were struck between 2026-08-29 and 2026-08-30**, as two waves of work
landed: burst grouping (FR-CULL-5), Flatpak packaging (FR-PLAT-LIN-3), FR-CULL-3 in full,
Android memory pressure and lost-root recovery (FR-PLAT-AND-5, FR-PLAT-AND-2), image intents
(FR-PLAT-AND-6), and the job runner (FR-PLAT-AND-4's Rust half). What remains of each is
recorded where it appears rather than deleted, because a requirement that is *half* met is the
one most likely to be reported as closed.

---

## 1. Plugins — 21 requirements, and a contradiction to resolve before any of them

**Untagged:** FR-PLG-1, -1a, -2a, -2b, -2c, -3, -3a, -4, -4a, -5, -5a, -5b, -5c, -6, -6a, -7, -8,
-9, -10, -11, -12.

No plugin host exists. No crate loads anything at runtime: there is no manifest reader, no WASM or
Lua engine, no registry, no signature check, no install path, no capability grant, no per-plugin
failure ledger. `declared/mod.rs` says as much in its own documentation — the operation format is
"not a plugin directory read at startup".

**Two of §3.10's requirements are met, and they are the interesting two.** FR-PLG-2 and FR-PLG-2d —
the declarative node format — are built and tagged: `core/dr-pipeline/ops/*.yaml` compiled by
`build.rs`, with the restricted expression grammar in `declared/expr.rs` and a parity test asserting
a declared operation and a hand-written one produce identical output.
[code-health.md §3](code-health.md) calls it "a working plugin system that happens to resolve at
build time", and that is exactly right. What is missing is not the format; it is everything that
would let somebody who is not in this repository use it.

**The contradiction.** [requirements.md §7](requirements.md) lists `| Plugin API | — |` among the
things deferred for v1 — a bare row, where most deferrals carry a justifying note. §3.10 then spends
roughly 280 lines and 23 requirement IDs specifying that same Plugin API in detail. Both statements
are in the register of record, and the traceability denominator counts the second one: 21 IDs, 12%
of all 179 defined requirements, worth about twelve points of coverage on their own — and nearly a
third of everything the matrix reports as uncovered. A reader looking at the coverage figure has no
way to know that, or that the subsystem behind it is one the same document says is not in this
version.

**And D16 is open.** [Decision D16](requirements.md) — plugin licensing — records that GPLv3
answers the derivative-work question differently for each of §3.10's three plugin forms, and that
this "must be answered *before* an ecosystem exists, not after", because a term introduced later
cannot be applied to plugins already written. D16 explicitly does not block FR-PLG-2; it blocks
publishing a third-party format as stable.

**What would resolve this:** an edit to `requirements.md`, not code. Either §7 drops the row, or
§3.10 is marked deferred with the two built requirements carved out. Until one of those happens the
coverage figure is measuring a decision that has already been taken, and taking it again every time
somebody reads the matrix.

---

## 2. Culling — the stated differentiator, half built

[D11](requirements.md) names culling "the core differentiator". FR-CULL-1, -2, -3, -4 and -8 through
-12 are built. Three are not.

**FR-CULL-3 — Raw-truth overlays. Built, all three bullets.** Focus peaking is
`core/dr-gpu/src/focus.rs` and `ui/dr-ui/src/peaking.rs`; the raw histogram and the raw clipping
indicators are `core/dr-gpu/src/raw_histogram.rs` and the second reading of the panel in
`histogram.slint`.

Worth recording, because it is the thing this entry previously got wrong and the next reader will
have to check again. The display histogram — `dr-gpu/src/histogram.rs`, `ui/dr-ui/src/histogram.rs`
— is **not** this requirement and never was: it is tagged FR-DSP-7, it reads `AdjustPass`'s 8-bit
output, it counts clipping as `r == 255`, and so it describes the frame the display is about to
show, after the whole develop chain. FR-CULL-3 asks for the *sensor data*, on the explicit grounds
that a rendered image "systematically lies about what is recoverable in the raw". The two now sit in
one panel behind a chip row, which is the arrangement that keeps them from being mistaken for each
other: they answer different questions and both are true.

What the raw reduction cannot answer is written down rather than left to be discovered —
[architecture.md §5.5](architecture.md) records why it reduces over the demosaiced texture instead
of the CFA samples §5.5 originally specified, and what that costs in what it can say.

**FR-CULL-5 — Burst and near-duplicate grouping. Built.** `core/dr-catalog/src/bursts.rs`:
frames join a burst when they are adjacent in time *and* look like the frame before them, compared
adjacent-pair-only in one ordered walk. Signatures are 64-bit difference hashes taken from the
thumbnails `dr-thumbs` already holds, on a background pass after the thumbnail sweep — nothing at
import, nothing at query time. Nothing scores or rejects a frame: the representative is the
earliest, a fact about the clock, and a new burst arrives *open* so the pass never takes a row off
the screen.

Two threads left hanging. `core/dr-face/src/calibrate.rs` still says "since FR-CULL-5 already
groups bursts, positives are bootstrapped from bursts" while in fact bootstrapping from confirmed
labels — that comment was a forward reference and is now simply wrong, rather than premature.
And `dr_catalog::bursts::choose_representative` is written and tested but bound to no gesture, so
today the only override is expanding the burst.

`core/dr-catalog/src/dedup.rs` remains a different thing: re-import detection under FR-CAT-11,
matching a file against one already catalogued, not two photographs against each other.

**FR-CULL-6 — Compare and survey.** Absent. No side-by-side view, no synchronised zoom or pan.
This is the one of the four with no adjacent machinery at all, and it is also the one that most
directly distinguishes culling from browsing.

**FR-CULL-7 — Culling on tablet.** Absent, and blocked by the three above rather than independent
of them: there is no separate tablet culling surface to build until there is something to put on it.

---

## 3. FR-DEV-3g — AI denoise

Promoted into v1 by [D11](requirements.md), and named there as the precondition for deferring AI
masking — the argument being that one learned stage earns the runtime that a second could then
reuse. Only classical noise reduction exists: `ops/noise_reduction.rs`, a bilateral filter in two
arrangements, exact for luminance and separable for chroma. It is good, and it is not this.

`models/` holds two face models and nothing else; `core/dr-segment/models/` holds a YOLO
segmentation model for subject masks. There is no denoise model, no learned demosaic, and no
inference path that is not face or segmentation.

The obstacle is not the pipeline. It is that [D13](requirements.md) — model licensing — is still
open for the models that already ship, and adding a third learned stage adds a third licence to
answer for. Building the runtime before that is settled means owning the same problem in one more
place.

---

## 4. The render path — FR-DSP-2, FR-DSP-4, NFR-RES-2

**FR-DSP-2 — Tiled computation. Unbuilt, and under challenge.** [architecture.md §6.2](architecture.md)
calls for tiling "from day one" on the grounds that retrofitting it is a rewrite. It was not built,
and the evidence has since moved. `core/dr-gpu/tests/frame_budget.rs` carries the argument in its
own header: one fused dispatch over a viewport-sized target is comfortably inside the frame budget,
and "if that stops being true, the recommendation to strike tiled computation from the interactive
path stops being supported, and this test is what says so."
[technical-debt.md TD-4](technical-debt.md) reaches the same place from the other direction — a
tiled convolution at clarity's radius reads nearly twice the taps that an untiled one does, so the
stage that looks most like it wants a tile cache is the stage that would be hurt most by one.

What exists is the declaration and not the mechanism: `DetailPass::radius` is documented as the halo
a tile would have to be grown by, with a test that pins it, and there is no scheduler to read it.
That is deliberate plumbing, not an oversight.

**So the open question here is not "when is tiling built" but "is FR-DSP-2 still a requirement".**
Two measurements say it costs more than it saves on the interactive path. Neither says anything
about the export path or about a device under memory pressure, which is where the case for it
actually lives — and that is spike S6, which has not run.

**FR-DSP-4 — Progressive refinement.** Unbuilt. FR-DSP-1's proxy rendering and TD-4's
quarter-resolution base are adjacent and are not it: both are fixed choices about what resolution to
compute at, where FR-DSP-4 asks for a first frame that is deliberately cheap and a second that
replaces it. Nothing tracks a "this frame is provisional" state.

**NFR-RES-2 — Images larger than GPU memory.** No answer, and §4.3 knows it: the requirement text
itself asks the reader to "decide explicitly" how ARCH §6.4 and NFR-RES-2 are reconciled. There is
no headroom budget, no allocation-failure fallback, and no spill. Spike S6 — a tiled pipeline on a
mid-range Android device with an image larger than available GPU memory — is the one that would
settle both this and FR-DSP-2, and there is no evidence it has run.

---

## 5. Android beyond running, and Flatpak

The Android app is not a stub — it builds an APK, runs the whole application, unpacks bundled face
models, and has been measured on a tablet ([faces.md §12.1](faces.md),
[technical-debt.md TD-1](technical-debt.md)). What is missing is the platform contract around it.

**FR-PLAT-AND-1 is tagged and should not be relied on.** The requirement demands that library access
be obtained *exclusively* through the Storage Access Framework. There is no SAF code: no
`ACTION_OPEN_DOCUMENT_TREE`, no `takePersistableUriPermission`, no `DocumentsContract`. The two tags
rest on a `SourceRef::Document` variant that nothing constructs and a volumes helper, which is the
"plumbing a future feature would use" case [CONTRIBUTING.md](../CONTRIBUTING.md) and
[code-health.md CH-4](code-health.md) both warn about. Android reaches a library through a Nextcloud
account or a folder, over paths, like the desktop.

That has a consequence for the rest of the cluster: **FR-PLAT-AND-2** — detecting the loss of a
granted tree permission and marking images offline rather than deleting rows — cannot be built until
there is a permission to lose. It is listed here as unbuilt, but it is blocked, not skipped.

**FR-PLAT-AND-4 — half built.** The runner is done (`core/dr-catalog/src/runner.rs`): the
queue that `jobs.rs` always had is now claimed from, completed, failed and recovered after a
crash, which is FR-PLAT-AND-3's resumability as much as this requirement's. What is missing is
the platform half — a foreground `Service`, `FOREGROUND_SERVICE` and `POST_NOTIFICATIONS` in the
manifest, and a stated Doze behaviour. The build step that blocked it is no longer a blocker: the
APK now compiles its own Java.

Note also that **no handler is registered**, deliberately. The only enqueue site reachable in the
shipping app produces remote thumbnail jobs already served by the async grid worker, and
`walk::scan_root` — which holds the other two enqueue sites — has no caller outside an example.
Wiring the sweep to claim from the queue is the honest next step and is an async rewrite of
`library.rs`.

**FR-PLAT-AND-5 — built.** A tiered eviction registry drives GPU caches, then proxies, then
thumbnails, from `MainEvent::LowMemory` and `MainEvent::Stop`.

**FR-PLAT-AND-6 — built, with one half unwired.** VIEW, SEND and SEND_MULTIPLE filters, the launch
Intent read over JNI, and an `ExportProvider` rooted at `getFilesDir()` rather than AndroidX's
`FileProvider`. The outbound share has no caller in `ui/` yet. **None of the runtime behaviour has
been exercised on a device** — the tests read the manifest and the Java through `include_str!`,
which catches a deleted filter but not a class loader that cannot find the class.

**FR-PLAT-LIN-3 — packaged, not satisfied.** There is a Flatpak manifest now, granting no
filesystem permission of any kind, plus AppStream metainfo and `docs/distribution.md`. The
requirement is still not met, and cannot be met by packaging: a folder library is chosen by typing
an absolute path, nothing in the tree calls the FileChooser portal, and inside the sandbox `$HOME`
holds only `.var/app/...`. `dr_plat::volumes()` reads `/proc/self/mountinfo`, so a card mounted on
the host is invisible to a sandboxed process as well. The fix is an `ashpd` directory picker beside
`LocalStorage::grant`, not a change to the manifest. No Flatpak has been built here —
`flatpak-builder` is not installed — so the permission set is reasoned, not observed.

**NFR-COMPAT-2 — distribution channels.** Unstated, and this is the requirement that makes the
others binding: §4.8 observes that the decision to publish on Play is what turns SAF from a
preference into a constraint. Spike S11, the Play permissions dry-run that would settle it, has not
run. Related, NFR-COMPAT-1's baseline is real but scattered — API 28/36 live in the Android
Dockerfile and are checked in CI against the built ELF, which is good — while the items the
requirement singles out are missing: whether `shaderFloat16` and 16-bit storage are required (the
one it flags as jeopardising R1), minimum RAM, minimum desktop Mesa, and a named reference device
from a second GPU vendor.

**NFR-OPS-2 and NFR-OPS-4.** Crash reporting is a `log::error!` panic hook on Android and nothing at
all on desktop: no local crash record, no backtrace capture, no upload path and therefore no opt-in
gate to guard it. Update and first run are undefined; the concrete reason NFR-OPS-4 gives — that D2
pins rawler at a non-SemVer alpha whose camera-support fixes users will need — is unaddressed, and
there is no update mechanism of any kind.

---

## 6. Accessibility and internationalisation — the hard half is done and the easy half is not

**NFR-A11Y-1 — Localisation.** `@tr(` appears **zero** times across 14,482 lines of Slint. That
number overstates the problem, because the part that is genuinely architectural was got right:
`LocalizedKey` keeps display strings out of `core/` entirely, every operation publishes a key rather
than a label, and `labels::resolve` is the single point where a key becomes text. What that single
point does, however, is a hardcoded English `match` in Rust source — so changing a translation
requires a recompile, which is the one thing the requirement explicitly forbids. There is no message
catalogue in any format, no locale-resolution rule, and no decision recorded about RTL.

The work left is therefore smaller than it looks and entirely mechanical: a catalogue format, a load
path behind `resolve`, and `@tr(` around the Slint literals. The design it needs already exists.

**NFR-A11Y-2 — Accessibility.** `accessible-*` appears five times in the whole interface, all five
on one control — the parameter slider in `adjust.slint` — and nothing is set from the Rust side at
all. Everything else in eighteen Slint files is unnamed to AT-SPI and TalkBack. The requirement's own
caveat, that Slint's Android accessibility needs verifying, is spike S13, which has not run.

**NFR-A11Y-3 — Colour-independent status.** No compliance work found. This is cheap to satisfy while
a control is being written and expensive to retrofit across forty of them, which is an argument for
doing it as part of the NFR-A11Y-2 pass rather than after it.

---

## 7. Catalog and sync

**FR-CAT-14 — Migration import.** Reading ratings, labels, keywords and collections out of a
Lightroom `.lrcat` or a darktable `library.db`. Unbuilt. The destination is not: keywords,
collections, ratings and the cross-device merge rules are all built and tested, and
`keywords.rs` already anticipates the arrival ("an import from Lightroom can bring in…"). What is
missing is only the two source adapters — which is a comparatively contained piece of work for a
requirement that decides whether somebody can try this software on a library they already have.

**FR-NC-11 — Initial catalog build.** Using WebDAV `SEARCH` (RFC 5323) against `/remote.php/dav/`,
filtered by mimetype and paginated, in preference to walking folders with PROPFIND. Unbuilt: no
`SEARCH` request is issued anywhere. The PROPFIND walk this exists to replace is fully built and
well optimised — ETag pruning under FR-NC-4 turns an unchanged 50k library into one request — so the
gap is narrower than it reads. It is the *first* build against a large remote library that pays, and
that is the moment a new user meets.

**FR-CAT-13 — XMP interoperability, tagged and not met.** Read and write standard XMP sidecars. The
single tag sits on `keywords.rs`, which stores keywords; no XMP is parsed or written anywhere in the
tree, and `dr-export`'s metadata module says so about its own half ("neither is read by `dr-decode`
today"). Listed here rather than silently, because a tag makes a gap invisible and this one is
load-bearing for interoperating with the editors FR-CAT-14 imports from.

---

## 8. The performance targets are unverified, not unmet

Eleven of the fifteen §4.1 targets carry no tag: NFR-P2, -P3, -P4, -P6, -P7, -P8, -P10, -P11, -P12,
-P14, -P15. That is the uninteresting part of this section.

The interesting part is that §8 and §4.1 both require the same thing, in the same words, and it does
not exist: an automated benchmark suite against a synthetic 50k catalog, run per commit, where **"a
regression beyond a stated tolerance is a build failure, not a notification."** There is no
`benches/` directory in the workspace, no criterion dependency, and no synthetic catalog. The three
CI workflows run `cargo fmt --check`, clippy, `cargo test --workspace`, a release build, an Android
cross-build and a layering check. None of them measures anything, so there is no baseline to
regress against and no tolerance to exceed.

What does exist is narrower and genuinely good: `dr-gpu/examples/frame_budget` is a real instrument,
its results are committed in [frame-budget.md](frame-budget.md) with the machine and profile named,
and TD-4's before-and-after was measured with it. But it is run by hand — frame-budget.md's own
instruction is "rerun and diff this file" — and the guard version that does live in CI skips itself
where there is no GPU adapter, which the workflow notes is the normal case on a runner, while
asserting its CPU half only when `debug_assertions` is off, which a dev-profile `cargo test` is not.
In CI it therefore asserts approximately nothing.

**The claim to take from this is precise.** Nothing here says the performance targets are missed.
Several are plausibly met. It says that if one were broken tomorrow, nobody would find out — which
is the failure mode §8 was written to prevent, and the reason it belongs in this document rather
than in a backlog.

---

## 9. Two core requirements that cannot be closed as written

**R1 — Cross-platform output within a bounded tolerance.** §2 states that the threshold "must be
fixed before spike S9", because S9 both validates R1 and calibrates what tolerance is achievable.
The threshold was never fixed and S9 has not run, so R1 currently has no acceptance criterion at
all — there is nothing a test could assert.

The matrix used to report R1 as *covered*, and what covered it was two string literals: fixtures
inside the traceability tool's own unit tests, which the tool scans along with everything else,
because a fixture demonstrating tag extraction was indistinguishable from a tag. The extractor now
asks where the tag sits — a tag is the first word of a comment, not a string appearing anywhere on a
line — and R1 is untagged again, which is the honest reading while it has no acceptance criterion to
tag anything against.
NFR-OPS-1 was covered by tags that were real rather than fixtures, which is the worse case of the
two: one on `compute_coverage` and one on the gesture extractor, both on the traceability tool. A
coverage calculation and a documentation generator are not diagnostics under any reading, and the
requirement asks for a rotating, size-capped on-disk log in the XDG state directory, credential
redaction, and a consented diagnostics bundle. None of that exists — logging goes to stderr and
logcat — so both tags have been removed and NFR-OPS-1 is untagged. It is the case
[CONTRIBUTING.md](../CONTRIBUTING.md) warns about in its own words: a tag proves a tag exists.

**R2 — Efficient display of huge RAW libraries.** Its acceptance criterion contains "*(figure
TBD)*" — the scroll velocity below which no cell may render as a placeholder — and asks for a stated
prefetch margin and cache-hit rate. No figure is stated anywhere in the tree, neither quantity is
measured, and [TD-2](technical-debt.md) and [TD-3](technical-debt.md) both describe the thumbnail
path falling short of it in ways that were measured. R2 was deliberately left untagged on this branch
for that reason: the machinery is substantial and the criterion is unmet and partly undefined.

Both belong with §8 above. A requirement whose threshold was never chosen and a target nothing
measures fail in the same way — not by being wrong, but by being unfalsifiable.

---

## 10. Spikes

§9 defines fourteen validation spikes and says of three of them: "S1, S2 and S10 are the three that
can invalidate the architecture."

Only **S1** (Slint + wgpu zero-copy on Linux) and **S14** (the face pipeline on a real library) have
recorded results. S14's are the best evidence of any spike — a dedicated document, a measured pass
over an 18,143-face library, a named device and a reproducible command — though D13's licensing half
remains open.

**S6, S9, S10, S11 and S13 show no evidence of having run at all.** Each is referenced only from the
requirement text that asks for it:

| Spike | Would settle | Blocked on |
|---|---|---|
| S6 | FR-DSP-2, NFR-RES-2 — tiling and images larger than GPU memory | Nothing; needs a device and a large image |
| S9 | R1's tolerance threshold, and therefore R1 | Nothing; the threshold is defined *by* running it |
| S10 | Whether SAF at 10k files meets NFR-P1/P3 | §5 — there is no SAF code to measure |
| S11 | NFR-COMPAT-2, and whether Play makes SAF binding | Nothing |
| S13 | NFR-A11Y-2 on Android | §6 — there is almost nothing to test with |

S2, S3, S4, S5, S7, S8 and S12 are also unrun, several with acknowledgements in the code that say
so (`dr-sync/src/upload.rs` on S8, `dr-sync-nextcloud/src/lib.rs` on S3). S2 is one of the three
architecture-invalidating spikes and needs Adreno and Mali hardware, which the manifest notes no
emulator represents.

The pattern is worth stating rather than leaving to be inferred: the spikes that ran are the ones
whose subject was being built anyway. The ones that did not are the ones that would have said
whether something *should* be built — which is the opposite of the order §9 asks for.

---

## 11. D12, which governs all of the above

[Decision D12 — scope versus pace](requirements.md) is still **OPEN**, and says:

> The calibration selected an ambitious feature set — full tablet editing, full ingest, culling as a
> differentiator, complete GPU masking, AI denoise, Fuji-first colour, deep sync, sidecar durability
> — against a stated pace of evenings and weekends, indefinitely.
>
> **Those are not compatible as stated.**

Sections 1 through 10 are what that incompatibility looks like eleven versions later, and they land
almost exactly where D12 predicted: tablet editing carries SAF at unproven scale, background
execution limits and two GPU vendors to validate (§5), and every one of those is unbuilt or unrun.
The parts that *were* built — the develop pipeline, sync, faces, the catalog — are the parts that
did not need a decision first.

D12 is not resolved by choosing to work faster. It is resolved by moving requirements across the
line into §7, which costs nothing but the admission, and which this document is intended to make
easy: every cluster above is a candidate, and each says what it would take to build and what it
would cost to drop. Resolving D12 sets D3 and [architecture.md §10](architecture.md)'s Phase 2.