fix(settings): stop offering a column the backend rejects

Settings -> Track List Columns listed two rows both called "Track
Name", one of which could not be ticked, and a screen reader heard
"Show the Track Name column" twice with nothing to tell them apart.

They are `titleArtist` and `trackName`, and the issue left open which
way to fix it: a second label so the sort dropdown and the configurator
can say different words, or drop the row because the user cannot select
it. The code settles that. `titleArtist` is not in
`tracklist.AllColumnIDs`, so `Config.Validate()` returns `unknown
track-list column ID: "titleArtist"` -- ticking the row sends a column
set the backend rejects, `config-page` swallows the rejection into a
`console.error`, and the tick reverts. A second label would have named
a control that cannot work.

So a definition says whether it is a *choice*, and the configurator
reads `CONFIGURABLE_COLUMN_IDS` rather than `Object.keys(COLUMN_DEFS)`.

The new test reads Go's own list out of `backend/tracklist/config.go`
rather than writing it down a third time, since a third copy is the
fault one step earlier. Verified by planting: with the filter removed
all four assertions fail with the defect's own numbers.

Not fixed here, and filed as #231: `SetTrackListColumns` assigns before
it validates, so a rejected list stays in memory and `Save()` validates
the whole config -- one tick and no setting saves for the rest of the
session. That is reachable from any invalid input, not from this row.

Closes #197

CLAUDE.md

@@ -3275,6 +3275,27 @@ its own duplicates apart) — and changing either is invisible against an
 existing `YJ_HOME`, whose `config.toml` already holds the old list, so
 `make sandbox-seed NAME=default` before believing the app.
 
+**And the *valid* columns are declared twice too, which is the pair
+that drifted.** `tracklist.AllColumnIDs` is what the backend accepts;
+`COLUMN_DEFS` is what the frontend knows how to draw, and they are not
+the same set — `titleArtist` is a definition and not a choice, since it
+is the phone's stacked column and is picked by width in
+`PHONE_COLUMN_IDS`. Settings built its list from `Object.keys(
+COLUMN_DEFS)` and so offered it: **two rows both called "Track Name"**
+(#197), the second unselectable, because ticking it sends a column set
+Go rejects with `unknown track-list column ID` and `config-page`
+swallows that into a `console.error`. `CONFIGURABLE_COLUMN_IDS` is what
+the configurator reads now, derived from a `configurable` flag on the
+definition, and `settings-column-list.test.ts` reads Go's own list out
+of the source rather than writing it down a third time — the rule being
+about every column, so checking one checks nothing.
+
+One thing it does **not** fix, because it is reachable from any invalid
+input rather than from that row: `SetTrackListColumns` assigns before it
+validates, so a rejected list stays in memory and `Save()` validates the
+whole config — one tick and **no setting saves for the rest of the
+session**, silently. That is #231.
+
 **Event-driven communication**: Backend emits events via Wails runtime; frontend stores subscribe to them. Event names are constants in `backend/events/`.
 
 `frontend/src/events.ts` is **generated** from `backend/events/events.go`

frontend/src/components/config-page/config-page.ts

@@ -51,7 +51,7 @@ import type { BackgroundShade } from '@store/theme-store';
 import type { IconStyle } from '@store/favorites-store';
 import {
     COLUMN_DEFS,
-    ALL_COLUMN_IDS,
+    CONFIGURABLE_COLUMN_IDS,
 } from '@components/track-list/columns';
 
 import './config-field';
@@ -1640,7 +1640,7 @@ export class ConfigPage extends ViewLifecycleMixin(LitElement) {
             ...this.trackListCtrl.columnIds,
         ];
 
-        const disabledIds = ALL_COLUMN_IDS.filter(
+        const disabledIds = CONFIGURABLE_COLUMN_IDS.filter(
             (id) => !enabledIds.includes(id),
         );
 

frontend/src/components/track-list/columns.ts

@@ -32,6 +32,18 @@ export interface ColumnDef {
     id: string;
     /** Human-readable header label. */
     label: string;
+    /**
+     * Whether Settings may offer this column. Defaults to true.
+     *
+     * A definition is not the same thing as a *choice*. `titleArtist`
+     * is the phone's stacked column, picked by width in
+     * `PHONE_COLUMN_IDS`, and `tracklist.AllColumnIDs` in Go does not
+     * list it — so a tick in the configurator sends a column set the
+     * backend rejects with `unknown track-list column ID`, the tick
+     * reverts on the next render, and the only trace is a
+     * `console.error` (#197).
+     */
+    configurable?: boolean;
     /** Extracts the display value from a track. */
     accessor: (track: library.Track) => string;
     /** Default CSS width (used when no saved width exists). */
@@ -98,11 +110,16 @@ export const COLUMN_DEFS: Record<string, ColumnDef> = {
     },
     titleArtist: {
         id: 'titleArtist',
-        // Named for what it sorts by, since that is the only place the
-        // label is user-visible: the phone has no column headers, and
-        // the page header's sort list is built from the *configured*
-        // columns rather than the drawn ones.
+        // Named for what it sorts by. That label is drawn nowhere
+        // today: the phone has no column headers, and the page header's
+        // sort list is built from the *configured* columns, which this
+        // one can never be — see `configurable` below.
         label: 'Track Name',
+        // Chosen by width, never by the user, and rejected by the
+        // backend if it ever were. #197: Settings listed it anyway, so
+        // there were two rows called "Track Name" and the second one
+        // could not be selected.
+        configurable: false,
         accessor: (t) => t.TrackName,
         defaultWidth: '1fr',
         comparator: (a, b) => compareStr(a.TrackName, b.TrackName),
@@ -266,10 +283,15 @@ export const COLUMN_DEFS: Record<string, ColumnDef> = {
 };
 
 /**
- * All column IDs in default display order.
- * Used by the settings UI to list available columns.
+ * The column IDs Settings may offer, in default display order.
+ *
+ * Not every definition is one: a column the user cannot choose has no
+ * row in the configurator, because a checkbox that cannot change
+ * anything is worse than an absent one — see `ColumnDef.configurable`.
  */
-export const ALL_COLUMN_IDS: string[] = Object.keys(COLUMN_DEFS);
+export const CONFIGURABLE_COLUMN_IDS: string[] = Object.keys(
+    COLUMN_DEFS,
+).filter((id) => COLUMN_DEFS[id]?.configurable !== false);
 
 /**
  * Column IDs that are always searched regardless of visibility.

frontend/test/components/settings-column-list.test.ts

@@ -0,0 +1,190 @@
+/**
+ * Settings offers the columns the backend will accept, and no others.
+ *
+ * The list is built from `COLUMN_DEFS`, which is the *drawing* table:
+ * every definition the track list knows how to render, including
+ * `titleArtist` — the phone's stacked column, chosen by width in
+ * `PHONE_COLUMN_IDS` and never by a person. `tracklist.AllColumnIDs` in
+ * Go does not list that id, so the configurator offered a nineteenth
+ * row that could not be ticked:
+ *
+ * ```
+ * validate = unknown track-list column ID: "titleArtist"
+ * titleArtist valid = false
+ * ```
+ *
+ * What a user saw was **two rows both called "Track Name"** (#197), one
+ * of which did nothing — and a screen reader heard "Show the Track Name
+ * column" twice with nothing to tell them apart, which is `a11y.32`'s
+ * complaint inside the list that was fixed for exactly that.
+ *
+ * It is worse than an inert control, which is why the duplicate name
+ * was not the thing to fix. `SetTrackListColumns` assigns before it
+ * validates, so a rejected list stays in memory and `Save()` validates
+ * the whole config:
+ *
+ * ```
+ * later, unrelated SetThemeAccentColor = could not save config: invalid
+ *   config: ... unknown track-list column ID: "titleArtist"
+ * ```
+ *
+ * — one tick and no setting saves for the rest of the session. That
+ * half is filed separately; this file keeps the row from being offered.
+ *
+ * The last test is the one that would have caught it when the column
+ * was added: the two lists are in different languages, so nothing but a
+ * sweep can hold them together.
+ */
+import { beforeEach, describe, expect, it } from 'vitest';
+
+import '@components/config-page/config-page';
+
+import {
+  COLUMN_DEFS,
+  CONFIGURABLE_COLUMN_IDS,
+} from '@components/track-list/columns';
+import { flush, stub } from '@test/support/harness';
+import { fixture, shadowAll } from '@test/support/render';
+
+/** Go's own list of column ids, as text. */
+const GO_CONFIG = Object.values(
+  import.meta.glob<string>('../../../backend/tracklist/config.go', {
+    eager: true,
+    query: '?raw',
+    import: 'default',
+  }),
+)[0];
+
+/**
+ * The ids `tracklist.AllColumnIDs` actually contains.
+ *
+ * Read out of the source rather than written down here, because a
+ * third copy of this list is a third thing to forget — which is the
+ * defect, one copy earlier.
+ */
+function goColumnIDs(source: string): string[] {
+  const constants = new Map<string, string>();
+  const constBlock = /const \(([\s\S]*?)\n\)/.exec(source)?.[1] ?? '';
+
+  for (const [, name, id] of constBlock.matchAll(
+    /(\w+)\s+ColumnID\s*=\s*"([^"]+)"/g,
+  )) {
+    constants.set(name!, id!);
+  }
+
+  const listBlock =
+    /var AllColumnIDs = \[\]ColumnID\{([\s\S]*?)\n\}/.exec(source)?.[1] ?? '';
+
+  return [...listBlock.matchAll(/(\w+),/g)]
+    .map(([, name]) => constants.get(name!))
+    .filter((id): id is string => id !== undefined);
+}
+
+/**
+ * The column rows, and only those.
+ *
+ * Settings’ view-visibility list (#25) is drawn with the same two
+ * classes, so a bare `.column-label` sweeps 29 rows across two
+ * sections — and "Albums" the destination sitting beside "Album" the
+ * column is not the fault this file is about. The `for`/`id` prefix is
+ * what tells them apart.
+ */
+const COLUMN_ROW_LABEL = 'label.column-label[for^="column-"]';
+const COLUMN_ROW_BOX = 'input.column-toggle[id^="column-"]';
+
+/** The rows the configurator draws, by their visible name. */
+async function columnRowNames(): Promise<string[]> {
+  const page = await fixture('config-page');
+
+  await flush();
+  await page.updateComplete;
+
+  // Every section renders collapsed, and a collapsed body is `hidden`.
+  for (const section of shadowAll<HTMLElement>(page, 'config-section')) {
+    section.shadowRoot
+      ?.querySelector<HTMLButtonElement>('button[aria-expanded="false"]')
+      ?.click();
+  }
+
+  await flush();
+  await page.updateComplete;
+
+  return shadowAll<HTMLElement>(page, COLUMN_ROW_LABEL).map(
+    (label) => label.textContent?.trim() ?? '',
+  );
+}
+
+describe('the Settings column list', () => {
+  beforeEach(() => {
+    for (const path of [
+      'library.Library.GetAllLibrariesWithTrackCounts',
+      'jobs.Service.GetJobs',
+      'download.Service.ListProviders',
+      'download.Service.ProviderKinds',
+    ]) {
+      stub(path, []);
+    }
+
+    stub('config.Config.GetShortcuts', {});
+    stub('config.Config.GetDownloadPreferences', {});
+    stub('config.Config.GetThemeAccentColor', '#ffd43b');
+    stub('config.Config.GetThemeBackgroundShade', 'dark');
+  });
+
+  it('names each row once', async () => {
+    const names = await columnRowNames();
+
+    // A sweep over nothing passes.
+    expect(names.length, 'the page draws column rows').toBeGreaterThan(5);
+
+    const seen = new Set<string>();
+    const duplicated = names.filter((name) => !seen.add(name));
+
+    expect(duplicated).toEqual([]);
+    expect(names.filter((n) => n === 'Track Name')).toHaveLength(1);
+  });
+
+  it('gives each checkbox a name that identifies it', async () => {
+    // The visible half above is what was reported; this is the half a
+    // screen reader gets, and it is the one `config-page` computes
+    // from the same string.
+    const page = await fixture('config-page');
+
+    await flush();
+    await page.updateComplete;
+
+    const labels = shadowAll<HTMLInputElement>(page, COLUMN_ROW_BOX).map(
+      (box) => box.getAttribute('aria-label') ?? '',
+    );
+
+    expect(labels.length, 'the page draws column checkboxes').toBeGreaterThan(5);
+    expect(new Set(labels).size).toBe(labels.length);
+  });
+});
+
+describe('the column table', () => {
+  it('offers no column the backend would reject', async () => {
+    const accepted = goColumnIDs(GO_CONFIG ?? '');
+
+    // Two non-vacuity guards: a glob that stopped matching, and a
+    // parse that stopped finding the list it names.
+    expect(GO_CONFIG, 'backend/tracklist/config.go is readable').toBeTruthy();
+    expect(accepted.length, 'AllColumnIDs was parsed').toBeGreaterThan(10);
+
+    expect(
+      CONFIGURABLE_COLUMN_IDS.filter((id) => !accepted.includes(id)),
+    ).toEqual([]);
+  });
+
+  it('still knows how to draw every column it offers', async () => {
+    // The filter must not have taken a column *out* of the drawing
+    // table: `configurable` says what Settings may list, not what the
+    // list may render.
+    expect(
+      CONFIGURABLE_COLUMN_IDS.filter((id) => COLUMN_DEFS[id] === undefined),
+    ).toEqual([]);
+    expect(CONFIGURABLE_COLUMN_IDS).not.toContain('titleArtist');
+    expect(COLUMN_DEFS['titleArtist'], 'the phone still has its column')
+      .toBeTruthy();
+  });
+});