diff --git a/docs/traceability.md b/docs/traceability.md
index 68cb37e..155ea81 100644
--- a/docs/traceability.md
+++ b/docs/traceability.md
@@ -9,8 +9,8 @@ Denominators are parsed from [`requirements.md`](requirements.md) at run time, n
 
 | Metric | Value |
 |---|---|
-| Source files scanned | 254 |
-| TRACES tags found | 732 |
+| Source files scanned | 256 |
+| TRACES tags found | 734 |
 | Requirements defined | 177 |
 | Requirements covered | 98 |
 | **Coverage** | **55.4%** (98/177) |
@@ -58,7 +58,7 @@ _None._
 | FR-CULL-9 | [`core/dr-catalog/src/faces.rs:1`](../core/dr-catalog/src/faces.rs#L1), [`core/dr-catalog/src/schema.rs:384`](../core/dr-catalog/src/schema.rs#L384), [`ui/dr-ui/src/faces.rs:1`](../ui/dr-ui/src/faces.rs#L1), [`ui/dr-ui/src/identity_ui.rs:1`](../ui/dr-ui/src/identity_ui.rs#L1) |
 | FR-DEV-2 | [`core/dr-pipeline/src/operation.rs:352`](../core/dr-pipeline/src/operation.rs#L352) |
 | FR-DEV-3 | [`core/dr-gpu/src/adjust.rs:2165`](../core/dr-gpu/src/adjust.rs#L2165), [`core/dr-gpu/src/adjust.rs:651`](../core/dr-gpu/src/adjust.rs#L651), [`core/dr-gpu/src/adjust.rs:770`](../core/dr-gpu/src/adjust.rs#L770), [`core/dr-gpu/src/adjust.rs:84`](../core/dr-gpu/src/adjust.rs#L84), [`core/dr-gpu/tests/tone_curve.rs:1`](../core/dr-gpu/tests/tone_curve.rs#L1), [`core/dr-pipeline/src/detail.rs:387`](../core/dr-pipeline/src/detail.rs#L387), [`core/dr-pipeline/src/detail.rs:465`](../core/dr-pipeline/src/detail.rs#L465), [`core/dr-pipeline/src/framing.rs:188`](../core/dr-pipeline/src/framing.rs#L188), [`core/dr-pipeline/src/framing.rs:362`](../core/dr-pipeline/src/framing.rs#L362), [`core/dr-pipeline/src/framing.rs:617`](../core/dr-pipeline/src/framing.rs#L617), [`core/dr-pipeline/src/graph.rs:169`](../core/dr-pipeline/src/graph.rs#L169), [`core/dr-pipeline/src/graph.rs:573`](../core/dr-pipeline/src/graph.rs#L573), [`core/dr-pipeline/src/mask.rs:120`](../core/dr-pipeline/src/mask.rs#L120), [`core/dr-pipeline/src/operation.rs:299`](../core/dr-pipeline/src/operation.rs#L299), [`core/dr-pipeline/src/operation.rs:479`](../core/dr-pipeline/src/operation.rs#L479), [`core/dr-pipeline/src/ops/capture_sharpen.rs:1`](../core/dr-pipeline/src/ops/capture_sharpen.rs#L1), [`core/dr-pipeline/src/ops/capture_sharpen.rs:207`](../core/dr-pipeline/src/ops/capture_sharpen.rs#L207), [`core/dr-pipeline/src/ops/curve.rs:1`](../core/dr-pipeline/src/ops/curve.rs#L1), [`core/dr-pipeline/src/ops/curve.rs:218`](../core/dr-pipeline/src/ops/curve.rs#L218), [`core/dr-pipeline/src/ops/curve.rs:631`](../core/dr-pipeline/src/ops/curve.rs#L631), [`core/dr-pipeline/src/ops/curve.rs:99`](../core/dr-pipeline/src/ops/curve.rs#L99), [`core/dr-pipeline/src/ops/local_contrast.rs:1`](../core/dr-pipeline/src/ops/local_contrast.rs#L1), [`core/dr-pipeline/src/ops/noise_reduction.rs:1`](../core/dr-pipeline/src/ops/noise_reduction.rs#L1), [`core/dr-pipeline/src/ops/noise_reduction.rs:270`](../core/dr-pipeline/src/ops/noise_reduction.rs#L270), [`core/dr-pipeline/src/sidecar.rs:156`](../core/dr-pipeline/src/sidecar.rs#L156), [`core/dr-pipeline/src/sidecar.rs:1627`](../core/dr-pipeline/src/sidecar.rs#L1627), [`core/dr-pipeline/src/sidecar.rs:1687`](../core/dr-pipeline/src/sidecar.rs#L1687), [`core/dr-pipeline/tests/tone_curve.rs:1`](../core/dr-pipeline/tests/tone_curve.rs#L1), [`ui/dr-ui/src/develop.rs:101`](../ui/dr-ui/src/develop.rs#L101), [`ui/dr-ui/src/develop.rs:1280`](../ui/dr-ui/src/develop.rs#L1280), [`ui/dr-ui/src/develop.rs:163`](../ui/dr-ui/src/develop.rs#L163), [`ui/dr-ui/src/develop.rs:1758`](../ui/dr-ui/src/develop.rs#L1758), [`ui/dr-ui/src/develop.rs:1776`](../ui/dr-ui/src/develop.rs#L1776), [`ui/dr-ui/src/develop.rs:1790`](../ui/dr-ui/src/develop.rs#L1790), [`ui/dr-ui/src/develop.rs:1812`](../ui/dr-ui/src/develop.rs#L1812), [`ui/dr-ui/src/develop.rs:1958`](../ui/dr-ui/src/develop.rs#L1958), [`ui/dr-ui/src/develop.rs:2056`](../ui/dr-ui/src/develop.rs#L2056), [`ui/dr-ui/src/develop.rs:326`](../ui/dr-ui/src/develop.rs#L326), [`ui/dr-ui/src/develop.rs:3287`](../ui/dr-ui/src/develop.rs#L3287), [`ui/dr-ui/src/develop.rs:363`](../ui/dr-ui/src/develop.rs#L363), [`ui/dr-ui/src/develop.rs:3851`](../ui/dr-ui/src/develop.rs#L3851), [`ui/dr-ui/src/develop.rs:3905`](../ui/dr-ui/src/develop.rs#L3905), [`ui/dr-ui/src/develop.rs:3949`](../ui/dr-ui/src/develop.rs#L3949), [`ui/dr-ui/src/develop.rs:3999`](../ui/dr-ui/src/develop.rs#L3999), [`ui/dr-ui/src/develop.rs:628`](../ui/dr-ui/src/develop.rs#L628), [`ui/dr-ui/src/develop.rs:675`](../ui/dr-ui/src/develop.rs#L675), [`ui/dr-ui/src/lib.rs:1422`](../ui/dr-ui/src/lib.rs#L1422), [`ui/dr-ui/src/lib.rs:2124`](../ui/dr-ui/src/lib.rs#L2124), [`ui/dr-ui/src/lib.rs:301`](../ui/dr-ui/src/lib.rs#L301), [`ui/dr-ui/src/library.rs:411`](../ui/dr-ui/src/library.rs#L411), [`ui/dr-ui/src/masks_ui.rs:218`](../ui/dr-ui/src/masks_ui.rs#L218), [`ui/dr-ui/src/masks_ui.rs:41`](../ui/dr-ui/src/masks_ui.rs#L41), [`ui/dr-ui/src/masks_ui.rs:816`](../ui/dr-ui/src/masks_ui.rs#L816), [`ui/dr-ui/src/masks_ui.rs:930`](../ui/dr-ui/src/masks_ui.rs#L930), [`ui/dr-ui/src/segmentation.rs:219`](../ui/dr-ui/src/segmentation.rs#L219), [`ui/dr-ui/src/segmentation.rs:322`](../ui/dr-ui/src/segmentation.rs#L322), [`ui/dr-ui/src/segmentation.rs:350`](../ui/dr-ui/src/segmentation.rs#L350), [`ui/dr-ui/ui/app.slint:2105`](../ui/dr-ui/ui/app.slint#L2105), [`ui/dr-ui/ui/app.slint:984`](../ui/dr-ui/ui/app.slint#L984) |
-| FR-DEV-3a | [`core/dr-pipeline/build.rs:1807`](../core/dr-pipeline/build.rs#L1807), [`core/dr-pipeline/ops/exposure.yaml:1`](../core/dr-pipeline/ops/exposure.yaml#L1), [`core/dr-pipeline/src/descriptor.rs:117`](../core/dr-pipeline/src/descriptor.rs#L117), [`core/dr-pipeline/src/descriptor.rs:157`](../core/dr-pipeline/src/descriptor.rs#L157), [`core/dr-pipeline/src/descriptor.rs:177`](../core/dr-pipeline/src/descriptor.rs#L177), [`core/dr-pipeline/src/descriptor.rs:232`](../core/dr-pipeline/src/descriptor.rs#L232), [`core/dr-pipeline/src/framing.rs:259`](../core/dr-pipeline/src/framing.rs#L259), [`core/dr-pipeline/src/graph.rs:23`](../core/dr-pipeline/src/graph.rs#L23), [`core/dr-pipeline/src/graph.rs:250`](../core/dr-pipeline/src/graph.rs#L250), [`core/dr-pipeline/src/graph.rs:45`](../core/dr-pipeline/src/graph.rs#L45), [`core/dr-pipeline/src/graph.rs:58`](../core/dr-pipeline/src/graph.rs#L58), [`core/dr-pipeline/src/mask.rs:954`](../core/dr-pipeline/src/mask.rs#L954), [`core/dr-pipeline/src/operation.rs:328`](../core/dr-pipeline/src/operation.rs#L328), [`core/dr-pipeline/src/ops/curve.rs:318`](../core/dr-pipeline/src/ops/curve.rs#L318), [`ui/dr-ui/src/develop.rs:1177`](../ui/dr-ui/src/develop.rs#L1177), [`ui/dr-ui/src/lib.rs:595`](../ui/dr-ui/src/lib.rs#L595) |
+| FR-DEV-3a | [`core/dr-pipeline/build.rs:1807`](../core/dr-pipeline/build.rs#L1807), [`core/dr-pipeline/ops/exposure.yaml:1`](../core/dr-pipeline/ops/exposure.yaml#L1), [`core/dr-pipeline/src/descriptor.rs:117`](../core/dr-pipeline/src/descriptor.rs#L117), [`core/dr-pipeline/src/descriptor.rs:157`](../core/dr-pipeline/src/descriptor.rs#L157), [`core/dr-pipeline/src/descriptor.rs:177`](../core/dr-pipeline/src/descriptor.rs#L177), [`core/dr-pipeline/src/descriptor.rs:232`](../core/dr-pipeline/src/descriptor.rs#L232), [`core/dr-pipeline/src/framing.rs:259`](../core/dr-pipeline/src/framing.rs#L259), [`core/dr-pipeline/src/graph.rs:23`](../core/dr-pipeline/src/graph.rs#L23), [`core/dr-pipeline/src/graph.rs:250`](../core/dr-pipeline/src/graph.rs#L250), [`core/dr-pipeline/src/graph.rs:45`](../core/dr-pipeline/src/graph.rs#L45), [`core/dr-pipeline/src/graph.rs:58`](../core/dr-pipeline/src/graph.rs#L58), [`core/dr-pipeline/src/mask.rs:954`](../core/dr-pipeline/src/mask.rs#L954), [`core/dr-pipeline/src/operation.rs:328`](../core/dr-pipeline/src/operation.rs#L328), [`core/dr-pipeline/src/ops/curve.rs:318`](../core/dr-pipeline/src/ops/curve.rs#L318), [`ui/dr-ui/src/develop.rs:1177`](../ui/dr-ui/src/develop.rs#L1177), [`ui/dr-ui/src/lib.rs:595`](../ui/dr-ui/src/lib.rs#L595), [`ui/dr-ui/tests/ui_names_no_operation.rs:1`](../ui/dr-ui/tests/ui_names_no_operation.rs#L1) |
 | FR-DEV-3b | [`core/dr-pipeline/src/descriptor.rs:177`](../core/dr-pipeline/src/descriptor.rs#L177), [`core/dr-pipeline/src/framing.rs:259`](../core/dr-pipeline/src/framing.rs#L259), [`core/dr-pipeline/src/graph.rs:58`](../core/dr-pipeline/src/graph.rs#L58), [`core/dr-pipeline/src/operation.rs:328`](../core/dr-pipeline/src/operation.rs#L328) |
 | FR-DEV-3c | [`core/dr-pipeline/build.rs:1807`](../core/dr-pipeline/build.rs#L1807), [`core/dr-pipeline/ops/exposure.yaml:1`](../core/dr-pipeline/ops/exposure.yaml#L1), [`core/dr-pipeline/src/graph.rs:250`](../core/dr-pipeline/src/graph.rs#L250), [`core/dr-pipeline/src/graph.rs:45`](../core/dr-pipeline/src/graph.rs#L45), [`core/dr-pipeline/src/mask.rs:954`](../core/dr-pipeline/src/mask.rs#L954), [`ui/dr-ui/src/develop.rs:4578`](../ui/dr-ui/src/develop.rs#L4578) |
 | FR-DEV-3d | [`core/dr-gpu/src/adjust.rs:1041`](../core/dr-gpu/src/adjust.rs#L1041), [`core/dr-gpu/src/adjust.rs:104`](../core/dr-gpu/src/adjust.rs#L104), [`core/dr-gpu/src/adjust.rs:770`](../core/dr-gpu/src/adjust.rs#L770), [`core/dr-gpu/src/adjust.rs:84`](../core/dr-gpu/src/adjust.rs#L84), [`core/dr-gpu/src/adjust.rs:986`](../core/dr-gpu/src/adjust.rs#L986), [`core/dr-gpu/tests/capture_sharpen.rs:434`](../core/dr-gpu/tests/capture_sharpen.rs#L434), [`core/dr-gpu/tests/detail_stage.rs:242`](../core/dr-gpu/tests/detail_stage.rs#L242), [`core/dr-gpu/tests/local_contrast.rs:476`](../core/dr-gpu/tests/local_contrast.rs#L476), [`core/dr-gpu/tests/noise_reduction.rs:556`](../core/dr-gpu/tests/noise_reduction.rs#L556), [`core/dr-pipeline/src/framing.rs:188`](../core/dr-pipeline/src/framing.rs#L188), [`core/dr-pipeline/src/graph.rs:612`](../core/dr-pipeline/src/graph.rs#L612), [`core/dr-pipeline/src/operation.rs:31`](../core/dr-pipeline/src/operation.rs#L31), [`core/dr-pipeline/src/operation.rs:352`](../core/dr-pipeline/src/operation.rs#L352), [`core/dr-pipeline/src/operation.rs:52`](../core/dr-pipeline/src/operation.rs#L52), [`core/dr-pipeline/src/operation.rs:70`](../core/dr-pipeline/src/operation.rs#L70) |
@@ -84,7 +84,7 @@ _None._
 | FR-EXP-9 | [`core/dr-decode/src/lib.rs:506`](../core/dr-decode/src/lib.rs#L506), [`core/dr-export/src/lib.rs:128`](../core/dr-export/src/lib.rs#L128), [`core/dr-export/src/lib.rs:1`](../core/dr-export/src/lib.rs#L1), [`core/dr-gpu/src/adjust.rs:1068`](../core/dr-gpu/src/adjust.rs#L1068), [`ui/dr-ui/src/develop.rs:2771`](../ui/dr-ui/src/develop.rs#L2771), [`ui/dr-ui/src/lib.rs:344`](../ui/dr-ui/src/lib.rs#L344) |
 | FR-NC-1 | [`core/dr-sync-nextcloud/src/auth.rs:132`](../core/dr-sync-nextcloud/src/auth.rs#L132), [`core/dr-sync-nextcloud/src/auth.rs:44`](../core/dr-sync-nextcloud/src/auth.rs#L44), [`core/dr-sync-nextcloud/src/session.rs:128`](../core/dr-sync-nextcloud/src/session.rs#L128), [`ui/dr-ui/src/launch.rs:256`](../ui/dr-ui/src/launch.rs#L256), [`ui/dr-ui/src/launch.rs:49`](../ui/dr-ui/src/launch.rs#L49), [`ui/dr-ui/src/launch_ui.rs:344`](../ui/dr-ui/src/launch_ui.rs#L344) |
 | FR-NC-10 | [`ui/dr-ui/src/export.rs:1`](../ui/dr-ui/src/export.rs#L1), [`ui/dr-ui/src/lib.rs:406`](../ui/dr-ui/src/lib.rs#L406), [`ui/dr-ui/src/library.rs:1588`](../ui/dr-ui/src/library.rs#L1588), [`ui/dr-ui/src/library.rs:448`](../ui/dr-ui/src/library.rs#L448), [`ui/dr-ui/src/library.rs:750`](../ui/dr-ui/src/library.rs#L750), [`ui/dr-ui/src/library.rs:953`](../ui/dr-ui/src/library.rs#L953), [`ui/dr-ui/src/library_ui.rs:1606`](../ui/dr-ui/src/library_ui.rs#L1606), [`ui/dr-ui/src/library_ui.rs:3362`](../ui/dr-ui/src/library_ui.rs#L3362), [`ui/dr-ui/src/library_ui.rs:498`](../ui/dr-ui/src/library_ui.rs#L498), [`ui/dr-ui/src/sidecar_cache.rs:1`](../ui/dr-ui/src/sidecar_cache.rs#L1) |
-| FR-NC-12 | [`core/dr-sync-nextcloud/src/lib.rs:34`](../core/dr-sync-nextcloud/src/lib.rs#L34), [`core/dr-sync-nextcloud/src/lib.rs:892`](../core/dr-sync-nextcloud/src/lib.rs#L892), [`core/dr-sync/src/lib.rs:157`](../core/dr-sync/src/lib.rs#L157), [`core/dr-sync/src/lib.rs:40`](../core/dr-sync/src/lib.rs#L40), [`core/dr-sync/src/reachability.rs:1`](../core/dr-sync/src/reachability.rs#L1) |
+| FR-NC-12 | [`core/dr-sync-nextcloud/src/lib.rs:34`](../core/dr-sync-nextcloud/src/lib.rs#L34), [`core/dr-sync-nextcloud/src/lib.rs:892`](../core/dr-sync-nextcloud/src/lib.rs#L892), [`core/dr-sync/src/lib.rs:157`](../core/dr-sync/src/lib.rs#L157), [`core/dr-sync/src/lib.rs:40`](../core/dr-sync/src/lib.rs#L40), [`core/dr-sync/src/reachability.rs:1`](../core/dr-sync/src/reachability.rs#L1), [`ui/dr-ui/src/remote.rs:1`](../ui/dr-ui/src/remote.rs#L1) |
 | FR-NC-2 | [`core/dr-sync-nextcloud/src/session.rs:128`](../core/dr-sync-nextcloud/src/session.rs#L128), [`core/dr-sync-nextcloud/src/session.rs:34`](../core/dr-sync-nextcloud/src/session.rs#L34) |
 | FR-NC-3 | [`core/dr-decode/src/locate.rs:1`](../core/dr-decode/src/locate.rs#L1), [`core/dr-decode/src/preview.rs:148`](../core/dr-decode/src/preview.rs#L148), [`core/dr-sync/src/capability.rs:41`](../core/dr-sync/src/capability.rs#L41), [`core/dr-thumbs/src/lib.rs:1`](../core/dr-thumbs/src/lib.rs#L1), [`ui/dr-ui/src/library.rs:1`](../ui/dr-ui/src/library.rs#L1), [`ui/dr-ui/src/library.rs:2604`](../ui/dr-ui/src/library.rs#L2604), [`ui/dr-ui/src/library.rs:2630`](../ui/dr-ui/src/library.rs#L2630), [`ui/dr-ui/src/library_ui.rs:1`](../ui/dr-ui/src/library_ui.rs#L1), [`ui/dr-ui/src/library_ui.rs:3624`](../ui/dr-ui/src/library_ui.rs#L3624), [`ui/dr-ui/src/library_ui.rs:4590`](../ui/dr-ui/src/library_ui.rs#L4590), [`ui/dr-ui/ui/app.slint:540`](../ui/dr-ui/ui/app.slint#L540), [`ui/dr-ui/ui/settings.slint:353`](../ui/dr-ui/ui/settings.slint#L353), [`ui/dr-ui/ui/settings.slint:72`](../ui/dr-ui/ui/settings.slint#L72) |
 | FR-NC-4 | [`core/dr-sync-nextcloud/src/propfind.rs:100`](../core/dr-sync-nextcloud/src/propfind.rs#L100), [`core/dr-sync-nextcloud/src/propfind.rs:51`](../core/dr-sync-nextcloud/src/propfind.rs#L51), [`core/dr-sync/src/capability.rs:6`](../core/dr-sync/src/capability.rs#L6), [`core/dr-sync/src/lib.rs:157`](../core/dr-sync/src/lib.rs#L157), [`core/dr-sync/src/scan.rs:93`](../core/dr-sync/src/scan.rs#L93), [`ui/dr-ui/src/launch.rs:49`](../ui/dr-ui/src/launch.rs#L49) |
diff --git a/ui/dr-ui/tests/ui_names_no_operation.rs b/ui/dr-ui/tests/ui_names_no_operation.rs
new file mode 100644
index 0000000..c7a20a1
--- /dev/null
+++ b/ui/dr-ui/tests/ui_names_no_operation.rs
@@ -0,0 +1,271 @@
+// TRACES: FR-DEV-3a
+//! The interface must not name an operation.
+//!
+//! This is the property the whole declarative pipeline rests on. A node in
+//! `core/dr-pipeline/ops/` is one file precisely because nothing in `ui/` has
+//! to learn about it: the panel builds controls from the parameter kinds the
+//! core publishes and never asks which operation it is drawing (ARCH §4.3a,
+//! FR-DEV-3a).
+//!
+//! Until now that was maintained by discipline alone, and the failure mode is
+//! silent and cumulative. Special-casing one operation to fix a layout problem
+//! is defensible on its own; by the fifth the panel names half the chain and
+//! "a new operation is one file" has quietly stopped being true, without any
+//! single commit having broken it.
+//!
+//! ## What counts as naming
+//!
+//! An operation id appearing as a **string literal** — `"exposure"`, in Rust
+//! or in Slint. That is the form a special case takes, because the id is how
+//! the panel would have to recognise the operation it wanted to treat
+//! differently.
+//!
+//! Bare words are deliberately not matched. Three ids — `texture`, `contrast`
+//! and `clarity` — are also ordinary graphics and English terms, and `texture`
+//! in particular appears throughout `dr-ui` meaning a GPU texture. Matching
+//! those would produce a test that fails constantly for reasons unrelated to
+//! the invariant, which is a test people delete.
+//!
+//! ## What is exempt
+//!
+//! Code under `#[cfg(test)]`. The invariant is about the interface that ships;
+//! a unit test asserting that `labels::resolve("clarity")` yields `"Clarity"`
+//! is testing the localisation table, not special-casing an operation. There is
+//! exactly one such case today, in `labels.rs`.
+
+use std::fs;
+use std::path::{Path, PathBuf};
+
+/// Below this, assume the scan broke rather than that the code is clean.
+///
+/// The dangerous failure of a test like this is not a false alarm, which
+/// someone investigates — it is silently examining nothing and reporting
+/// success. An early version cut each file at the first *textual* match of
+/// `#[cfg(test)]`, which in `develop.rs` is a doc comment discussing the
+/// attribute: it read 18% of the most important file in the scan and passed.
+///
+/// `dr-ui` is currently 75% shipping code by line. The floor is set well under
+/// that so ordinary movement does not trip it, and well over the number a
+/// parsing bug produces.
+const MIN_SHIPPING_FRACTION: f64 = 0.60;
+
+/// Every operation id the pipeline declares.
+///
+/// Read from the declarations rather than listed here, so a node added
+/// tomorrow is covered without anyone remembering to extend this file — the
+/// same reason `traceability` parses its denominators from `requirements.md`
+/// at run time.
+fn operation_ids(ops_dir: &Path) -> Vec<String> {
+    let mut ids = Vec::new();
+
+    let entries =
+        fs::read_dir(ops_dir).unwrap_or_else(|e| panic!("cannot read {}: {e}", ops_dir.display()));
+
+    for entry in entries {
+        let path = entry.expect("read dir entry").path();
+
+        if path.extension().and_then(|e| e.to_str()) != Some("yaml") {
+            continue;
+        }
+        // `_helpers.yaml` declares the shared WGSL library, not a node, and has
+        // no `id:`. The leading underscore is the documented marker.
+        if path
+            .file_name()
+            .and_then(|n| n.to_str())
+            .is_some_and(|n| n.starts_with('_'))
+        {
+            continue;
+        }
+
+        let text = fs::read_to_string(&path)
+            .unwrap_or_else(|e| panic!("cannot read {}: {e}", path.display()));
+
+        let id = text
+            .lines()
+            .find_map(|l| l.strip_prefix("id:"))
+            .map(str::trim)
+            .unwrap_or_else(|| panic!("{} declares no id:", path.display()));
+
+        ids.push(id.to_string());
+    }
+
+    assert!(
+        !ids.is_empty(),
+        "found no operation declarations in {} — the path is wrong, and a scan \
+         over nothing passes for the wrong reason",
+        ops_dir.display()
+    );
+
+    ids
+}
+
+/// Every `.rs` and `.slint` file under a directory.
+fn sources(dir: &Path, out: &mut Vec<PathBuf>) {
+    let entries =
+        fs::read_dir(dir).unwrap_or_else(|e| panic!("cannot read {}: {e}", dir.display()));
+
+    for entry in entries {
+        let path = entry.expect("read dir entry").path();
+        if path.is_dir() {
+            sources(&path, out);
+        } else if matches!(
+            path.extension().and_then(|e| e.to_str()),
+            Some("rs") | Some("slint")
+        ) {
+            out.push(path);
+        }
+    }
+}
+
+/// Blank out string literals and line comments, so a brace inside either does
+/// not move the depth count.
+///
+/// Raw strings and block comments are not handled. Neither appears around a
+/// `#[cfg(test)]` item in this crate, and [`MIN_SHIPPING_FRACTION`] is the
+/// backstop if that ever stops being true.
+fn strip_literals_and_comments(line: &str) -> String {
+    let mut out = String::with_capacity(line.len());
+    let mut chars = line.chars().peekable();
+    let mut in_string = false;
+
+    while let Some(c) = chars.next() {
+        if in_string {
+            match c {
+                '\\' => {
+                    chars.next();
+                }
+                '"' => in_string = false,
+                _ => {}
+            }
+            continue;
+        }
+        match c {
+            '"' => in_string = true,
+            '/' if chars.peek() == Some(&'/') => break,
+            _ => out.push(c),
+        }
+    }
+
+    out
+}
+
+/// The lines of a file that ship, each with its 1-based number.
+///
+/// For Rust, every `#[cfg(test)]` item is dropped. The attribute must be the
+/// whole line — a doc comment *mentioning* it is prose, not an attribute, and
+/// treating the two alike is the bug [`MIN_SHIPPING_FRACTION`] describes.
+fn shipping_lines(path: &Path, text: &str) -> Vec<(usize, String)> {
+    let lines: Vec<&str> = text.lines().collect();
+
+    if path.extension().and_then(|e| e.to_str()) != Some("rs") {
+        return lines
+            .iter()
+            .enumerate()
+            .map(|(i, l)| (i + 1, (*l).to_string()))
+            .collect();
+    }
+
+    let mut out = Vec::new();
+    let mut i = 0;
+
+    while i < lines.len() {
+        if lines[i].trim() != "#[cfg(test)]" {
+            out.push((i + 1, lines[i].to_string()));
+            i += 1;
+            continue;
+        }
+
+        // Skip the item the attribute applies to: through its brace block, or
+        // to the `;` if it has none — `#[cfg(test)] use ...;` is legal.
+        let mut j = i + 1;
+        let mut depth: i32 = 0;
+        let mut opened = false;
+
+        while j < lines.len() {
+            let stripped = strip_literals_and_comments(lines[j]);
+            depth += stripped.matches('{').count() as i32;
+            depth -= stripped.matches('}').count() as i32;
+
+            if stripped.contains('{') {
+                opened = true;
+            }
+            if opened && depth <= 0 {
+                break;
+            }
+            if !opened && stripped.contains(';') {
+                break;
+            }
+            j += 1;
+        }
+
+        i = j + 1;
+    }
+
+    out
+}
+
+#[test]
+fn the_interface_names_no_operation() {
+    let crate_root = Path::new(env!("CARGO_MANIFEST_DIR"));
+    let repo = crate_root
+        .parent()
+        .and_then(Path::parent)
+        .expect("ui/dr-ui has a grandparent");
+
+    let ids = operation_ids(&repo.join("core/dr-pipeline/ops"));
+
+    let mut files = Vec::new();
+    sources(&crate_root.join("src"), &mut files);
+    sources(&crate_root.join("ui"), &mut files);
+
+    let mut offences = Vec::new();
+    let mut total = 0usize;
+    let mut scanned = 0usize;
+
+    for path in &files {
+        let text = fs::read_to_string(path)
+            .unwrap_or_else(|e| panic!("cannot read {}: {e}", path.display()));
+
+        total += text.lines().count();
+        let shipping = shipping_lines(path, &text);
+        scanned += shipping.len();
+
+        for (n, line) in shipping {
+            for id in &ids {
+                if line.contains(&format!("\"{id}\"")) {
+                    offences.push(format!(
+                        "  {}:{n} names \"{id}\"\n      {}",
+                        path.strip_prefix(repo).unwrap_or(path).display(),
+                        line.trim()
+                    ));
+                }
+            }
+        }
+    }
+
+    let fraction = scanned as f64 / total as f64;
+    assert!(
+        fraction >= MIN_SHIPPING_FRACTION,
+        "only {scanned} of {total} lines ({:.0}%) were scanned, below the {:.0}% \
+         floor — `shipping_lines` is dropping code it should be reading, and \
+         this test is passing without having looked. Fix the scan before \
+         trusting the result.",
+        fraction * 100.0,
+        MIN_SHIPPING_FRACTION * 100.0
+    );
+
+    assert!(
+        offences.is_empty(),
+        "\n\nFR-DEV-3a: the interface must not name an operation.\n\n{}\n\n\
+         The core declares capabilities and the frontend composes them, which is \
+         why adding a develop node is one file in core/dr-pipeline/ops/ and \
+         touches no UI. A special case here takes that away from every node \
+         added afterwards.\n\n\
+         If a node needs presentation the panel cannot currently give it, the \
+         answer is a `presentation:` hint in its declaration and a `WidgetKind` \
+         the panel implements for every node that asks — see \
+         core/dr-pipeline/ops/README.md and `develop::supported`.\n\n\
+         Test code is exempt; this scans only what ships.\n",
+        offences.join("\n")
+    );
+}