Write down what is not built, so the gap reads as a decision

The traceability matrix reports one number and cannot say what it means.
An untagged requirement is either one nobody built or one somebody built
and did not label, and both look identical in the summary table. Eight of
the second kind were tagged in the previous commit. This is the first
kind, written out with the reasoning, so that the distance between the
register and the binary is something a reader can see rather than
reconstruct from a percentage.

Eleven clusters, each verified against the tree rather than inherited
from a survey. Several turned out to be more interesting than "not done":

Plugins are 21 untagged requirements — nearly a third of the shortfall —
and §7 already lists the Plugin API as out of scope for v1 while §3.10
spends 280 lines specifying it. The two that *are* built, FR-PLG-2 and
FR-PLG-2d, are the declarative operation format, which is a plugin system
that resolves at build time. The fix here is an edit to requirements.md,
not code, and D16 has to be answered before any format is called stable.

FR-DSP-2 is not merely unbuilt; it is under challenge. frame_budget.rs
and TD-4 independently argue that tiling costs more than it saves on the
interactive path, so the open question is whether the requirement should
survive, not when it will be met — and the spike that would settle it, S6,
has not run.

NFR-A11Y-1's hard half is done and its easy half is not. LocalizedKey
already keeps display strings out of core/ and labels::resolve is a single
resolution point; what that point does is a hardcoded English match, so a
translation needs a recompile, which is the one thing the requirement
forbids.

The §4.1 performance targets are unverified rather than unmet. §8 requires
a per-commit benchmark suite whose regressions fail the build; there is no
benches/ directory, no criterion, and no benchmark step in any of the
three CI workflows. The one guard that does live in CI skips itself
without a GPU adapter and asserts its CPU half only in release, while CI
tests in dev. Nothing says the targets are missed. It says nobody would
find out.

And three requirements are reported as covered while not being met: R1 and
NFR-OPS-1 are tagged only by string literals inside the traceability
tool's own tests, which it scans along with everything else, and
FR-CAT-13's single tag sits on keyword storage while no XMP is parsed or
written anywhere. CONTRIBUTING already warns that a tag proves a tag
exists; these are the specific ones.

Focus peaking, burst grouping, Flatpak packaging and the Android platform
integration are being built in parallel and are marked in progress rather
than listed as absent, so those lines can be struck as they land.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/outstanding.md

@@ -0,0 +1,351 @@
+# 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.
+
+**Four of these are being built right now**, in parallel worktrees, and are marked **⟳ in
+progress** where they appear: focus peaking (part of FR-CULL-3), burst grouping (FR-CULL-5),
+Flatpak packaging (FR-PLAT-LIN-3), and Android platform integration (FR-PLAT-AND-2/4/5/6). Strike
+those lines as they land rather than rewriting around them.
+
+---
+
+## 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, -4 and -8 through -12
+are built. Four are not.
+
+**FR-CULL-3 — Raw-truth overlays.** Focus peaking does not exist anywhere; the string appears zero
+times in the tree. A histogram and clipping indicators *do* exist, but they are not the ones this
+requirement asks for: they live in the develop view under FR-DSP-7, they are threshold readouts
+rather than per-pixel overlays on the image, and `develop.rs` says plainly that what they count is
+"the levels the display will show" — the pipeline result, not the sensor data. FR-CULL-3 exists
+because a culling decision made against a rendered preview is a decision made against the wrong
+image. **⟳ in progress** (focus peaking).
+
+**FR-CULL-5 — Burst and near-duplicate grouping.** Absent. Worth knowing before it is built:
+`core/dr-face/src/calibrate.rs` already *assumes* it exists — "since FR-CULL-5 already groups
+bursts, positives are bootstrapped from bursts" — and in fact bootstraps from confirmed labels
+instead. That comment is a forward reference to this requirement and will need correcting either
+way. `core/dr-catalog/src/dedup.rs` is not this: it is re-import detection under FR-CAT-11, matching
+a file against one already catalogued, not two photographs against each other. **⟳ in progress**.
+
+**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** (managed background execution, foreground service for exports, stated Doze
+behaviour): the manifest declares one activity, no service, and neither `FOREGROUND_SERVICE` nor
+`POST_NOTIFICATIONS`. **FR-PLAT-AND-5** (`onTrimMemory` with a stated eviction order): no callback
+is registered, though the eviction order it is supposed to drive is specified in FR-NC-6's text.
+**FR-PLAT-AND-6** (view and share intents, `FileProvider`): the only intent filter is
+`MAIN`/`LAUNCHER`. **⟳ in progress** for this group.
+
+**FR-PLAT-LIN-3 — Flatpak.** `packaging/` holds an Arch `PKGBUILD` and a `.desktop` entry. There is
+no Flatpak manifest, nothing goes through a portal, and `platform/dr-plat/src/secrets.rs` talks to
+the Secret Service directly rather than through the portal the requirement names. **⟳ in progress**.
+
+**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.
+
+Worse, the matrix reports R1 as *covered*. Both of its tags are string literals inside the
+traceability tool's own unit tests (`tools/traceability/src/lib.rs`), which the tool scans along with
+everything else, because a fixture demonstrating tag extraction is indistinguishable from a tag.
+NFR-OPS-1 is covered the same way, from a tag on `compute_coverage` — and no rotating, size-capped
+on-disk log exists; logging goes to stderr and logcat. These are two of the cases
+[CONTRIBUTING.md](../CONTRIBUTING.md) already warns about, now named.
+
+**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.