chore(tabs): remove the home-tab constructor, keep the sentinel

scripts/homeSentinelSnapshot.test.ts

@@ -1,12 +1,13 @@
 import assert from 'node:assert/strict';
 import test from 'node:test';
 
-// The home screen sits in a tab, and that tab's path is the sentinel string
-// `'HOME'` rather than a file. `serializeState` filtered on `path !== ''`, so
-// the sentinel was written into the session snapshot; `restoreState` accepted
-// any non-empty string, so it came back; and startup then asked the backend to
-// read a file called `HOME`. The failure left a phantom tab that can never be
-// read, and a window whose only tab was the home screen came back empty.
+// The home screen used to sit in a tab, and that tab's path was the sentinel
+// string `'HOME'` rather than a file. `serializeState` filtered on
+// `path !== ''`, so the sentinel was written into the session snapshot;
+// `restoreState` accepted any non-empty string, so it came back; and startup
+// then asked the backend to read a file called `HOME`. The failure left a
+// phantom tab that can never be read, and a window whose only tab was the home
+// screen came back empty.
 //
 // `hasRealFilePath` in utils/tabFileActions.ts is the project's existing answer
 // to "is this path a file" — every other caller already used it.
@@ -41,16 +42,33 @@ g.window.__TAURI_INTERNALS__ = {
 };
 
 const { tabManager } = await import('../src/lib/stores/tabs.svelte.js');
+const { HOME_TAB_PATH } = await import('../src/lib/utils/homeTab.js');
 
 function reset() {
 	tabManager.closeAll();
 	localStore.clear();
 }
 
+/**
+ * A tab bearing the home sentinel.
+ *
+ * `TabManager.addHomeTab` used to build one; it lost its last caller when
+ * Ctrl+T settled on "new file" (#480) and was removed with it. The write-side
+ * rule it exercised here outlives it, because the two sides are one filter:
+ * `serializeState` and `restoreState` both reject on `hasRealFilePath`, and the
+ * read side still meets `HOME` in snapshots this app wrote before the fix.
+ * Pinning the write side is what keeps a future writer from putting the
+ * sentinel back into the file the read side is busy defending against.
+ */
+function openHomeTab() {
+	tabManager.addNewTab();
+	tabManager.activeTab!.path = HOME_TAB_PATH;
+}
+
 test('a session snapshot never carries the home tab', () => {
 	reset();
 	tabManager.addTab('/notes/a.md');
-	tabManager.addHomeTab();
+	openHomeTab();
 
 	const snapshot = JSON.parse(tabManager.serializeState());
 
@@ -62,7 +80,7 @@ test('a session snapshot never carries the home tab', () => {
 
 test('a window showing only the home tab writes an empty snapshot, not a HOME one', () => {
 	reset();
-	tabManager.addHomeTab();
+	openHomeTab();
 
 	assert.deepEqual(JSON.parse(tabManager.serializeState()).tabs, []);
 });

scripts/homeTabRender.test.ts

@@ -183,11 +183,33 @@ function reset() {
 	localStore.clear();
 }
 
+/**
+ * A tab bearing the home sentinel.
+ *
+ * `TabManager.addHomeTab` used to build one and these tests used to call it.
+ * That method lost its last caller when Ctrl+T settled on "new file" (#480)
+ * and was removed with it, so the state is assembled here instead.
+ *
+ * The gate still has to recognise the sentinel, which is why these tests did
+ * not go with the constructor: a session snapshot written before #401 can
+ * still hand a `HOME` path to a running window, and what keeps such a tab out
+ * is precisely the recognition this file evaluates.
+ *
+ * Setting `path` is the whole of it — `isHomePath` is a predicate over `path`
+ * and nothing else, which is the property the title test below pins. Building
+ * the state this way states that outright rather than inheriting a title from
+ * a constructor the gate is required to ignore.
+ */
+function openHomeTab() {
+	tabManager.addNewTab();
+	tabManager.activeTab!.path = HOME_TAB_PATH;
+}
+
 // --------------------------------------------------------------- the regression
 
 test('the home tab renders the home screen, not an empty document', () => {
 	reset();
-	tabManager.addHomeTab();
+	openHomeTab();
 
 	assert.equal(tabManager.activeTab?.path, HOME_TAB_PATH, 'precondition: the home tab is active');
 	assert.equal(
@@ -199,11 +221,12 @@ test('the home tab renders the home screen, not an empty document', () => {
 });
 
 test('a home tab opened next to files still renders the home screen', () => {
-	// Ctrl+T from a window that already has documents open — the reported path.
+	// Ctrl+T from a window that already had documents open — the path #392 was
+	// reported from, and the one a pre-#401 snapshot reproduces on startup.
 	reset();
 	tabManager.addTab('/notes/a.md');
 	tabManager.addTab('/notes/b.md');
-	tabManager.addHomeTab();
+	openHomeTab();
 
 	assert.equal(showsDocumentContainer(), false, `blank home tab alongside open files. Gate: ${gateSource}`);
 });
@@ -214,7 +237,7 @@ test('the home screen is reached by tab kind, never by the tab title', () => {
 	// `Recents` used to be enough to hide the editor. Nothing about which
 	// branch runs may depend on it.
 	reset();
-	tabManager.addHomeTab();
+	openHomeTab();
 	const home = tabManager.activeTab!;
 
 	for (const { code } of getSupportedLanguages()) {
@@ -273,15 +296,15 @@ test('the Home toolbar button still overlays the home screen on any tab', () =>
 	tabManager.addNewTab();
 	assert.equal(showsDocumentContainer(true), false, 'an untitled tab with showHome set');
 
-	tabManager.addHomeTab();
+	openHomeTab();
 	assert.equal(showsDocumentContainer(true), false, 'the home tab with showHome set');
 });
 
 test('switching from the home tab back to a file returns to the document', () => {
 	reset();
 	tabManager.addTab('/notes/a.md');
 	const file = tabManager.activeTab!.id;
-	tabManager.addHomeTab();
+	openHomeTab();
 	assert.equal(showsDocumentContainer(), false);
 
 	tabManager.setActive(file);

scripts/lossyDecodeSaveGuard.test.ts

@@ -60,7 +60,10 @@ test('the tab carries the fidelity of its buffer', () => {
 	assert.match(tabs, /hasReplacementChars: boolean;/);
 	assert.doesNotMatch(tabs, /hasReplacementChars\?: boolean;/);
 	assert.match(tabs, /setTabDecodedLossy\(id: string, lossy: boolean\)/);
-	assert.equal(tabs.match(/hasReplacementChars: false/g)?.length, 4);
+	// One per Tab construction site in this store: restoreState, addTab,
+	// addNewTab. It was four until addHomeTab lost its last caller and was
+	// removed (#480). A new site that forgets the field moves this number.
+	assert.equal(tabs.match(/hasReplacementChars: false/g)?.length, 3);
 });
 
 test('every load decides the flag instead of leaving it stale', () => {

scripts/renderedHtmlField.test.ts

@@ -433,7 +433,6 @@ test('every Tab construction site starts the rendered-HTML field empty', () => {
 	tabManager.restoreState(JSON.stringify({ tabs: [{ path: '/notes/b.md', title: 'b.md' }] }));
 	tabManager.addTab('/notes/a.md', '# a\n');
 	tabManager.addNewTab();
-	tabManager.addHomeTab();
 	tabManager.insertTransferredTab({
 		path: '/notes/c.md',
 		title: 'c.md',
@@ -452,7 +451,7 @@ test('every Tab construction site starts the rendered-HTML field empty', () => {
 		hasReplacementChars: false,
 	});
 
-	assert.equal(tabManager.tabs.length, 5, 'precondition: every construction site produced a tab');
+	assert.equal(tabManager.tabs.length, 4, 'precondition: every construction site produced a tab');
 	for (const tab of tabManager.tabs) {
 		assert.equal(tab.content, '', `${tab.path || tab.title} was constructed with a non-empty content field`);
 	}

scripts/tabPathIdentity.test.ts

@@ -190,13 +190,14 @@ test('untitled tabs are not files and do not collide', () => {
 	assert.equal(tabsFor('').length, 3);
 });
 
-test('the home tab is a singleton on its own terms, not through the path rule', () => {
-	reset();
-	tabManager.addHomeTab();
-	const home = tabManager.activeTabId;
-	tabManager.addTab('/notes/a.md');
-	tabManager.addHomeTab();
-
-	assert.equal(tabsFor('HOME').length, 1);
-	assert.equal(tabManager.activeTabId, home);
-});
+// There used to be a test here that the home tab was a singleton on its own
+// terms rather than through the path rule: `addHomeTab` re-activated the
+// existing home tab instead of building a second one, and it had to, because
+// `claimPath` returns early for anything that is not a real file path and so
+// would never have de-duplicated two of them.
+//
+// `addHomeTab` was the only way to make a home tab and it is gone (#480), which
+// takes the singleton rule with it — there is no longer a second call to make.
+// The half that outlives it, that the sentinel is not a file path and is not
+// subject to the claim rule, is `hasRealFilePath`'s job and is covered where
+// that predicate is: homeSentinelSnapshot.test.ts and homeTabRender.test.ts.

scripts/untitledTitle.test.ts

@@ -40,7 +40,9 @@ test('works with localized bases', () => {
 test('new tabs are created with numbered untitled titles', () => {
 	const tabs = readSource('src/lib/stores/tabs.svelte.ts');
 	assert.match(tabs, /nextUntitledTitle\(/);
-	// both creation paths go through the helper
-	const addNewTab = sliceBetween(tabs, 'addNewTab()', 'addHomeTab()');
+	// both creation paths go through the helper. The slice ends at the next
+	// method after `addNewTab`, which used to be `addHomeTab` until that one
+	// lost its last caller and was removed (#480).
+	const addNewTab = sliceBetween(tabs, 'addNewTab()', 'insertTransferredTab(');
 	assert.match(addNewTab, /nextUntitledTitle\(/);
 });

src/lib/MarkdownViewer.svelte

@@ -3321,7 +3321,6 @@ import { createDocumentSession, type LoadMarkdownOptions } from './sessions/docu
 								ontoggleEdit={() => toggleEdit()}
 								ontoggleLive={toggleLiveMode}
 								ontoggleSplit={() => tabManager.activeTabId && toggleSplitView(tabManager.activeTabId)}
-								onhome={() => (showHome = true)}
 								onnextTab={() => tabManager.cycleTab('next')}
 								onprevTab={() => tabManager.cycleTab('prev')}
 								onundoClose={handleUndoCloseTab}

src/lib/components/Editor.svelte

@@ -47,7 +47,6 @@
 		ontoggleEdit,
 		ontoggleLive,
 		ontoggleSplit,
-		onhome,
 		onnextTab,
 		onprevTab,
 		onundoClose,
@@ -65,7 +64,6 @@
 		ontoggleEdit?: () => void;
 		ontoggleLive?: () => void;
 		ontoggleSplit?: () => void;
-		onhome?: () => void;
 		onnextTab?: () => void;
 		onprevTab?: () => void;
 		onundoClose?: () => void;

src/lib/stores/tabs.svelte.ts

@@ -2,7 +2,6 @@ import { t } from '../utils/i18n.js';
 import { nextUntitledTitle } from '../utils/untitledTitle.js';
 import { settings } from './settings.svelte.js';
 import { hasRealFilePath } from '../utils/tabFileActions.js';
-import { HOME_TAB_PATH, isHomePath } from '../utils/homeTab.js';
 import { buildTransferredTab, type TransferableTab } from '../utils/tabTransfer.js';
 import { canonicalizePath, isSameFilePath } from '../utils/pathIdentity.js';
 import { retainTabModels } from '../utils/tabModels.js';
@@ -214,9 +213,9 @@ class TabManager {
 	 * Untitled tabs have no disk backing and are resolved at close, so they
 	 * are not persisted.
 	 *
-	 * The filter is `hasRealFilePath`, not `path !== ''`: the home screen sits
-	 * in a tab whose path is `HOME_TAB_PATH`, which passes the non-empty test
-	 * and used to be written into the snapshot. Restoring it then asked the
+	 * The filter is `hasRealFilePath`, not `path !== ''`: the home screen used
+	 * to sit in a tab whose path is `HOME_TAB_PATH`, which passes the non-empty
+	 * test and so was written into the snapshot. Restoring it then asked the
 	 * backend to read a file under that name, and the failure left a
 	 * permanently unreadable phantom tab — or, when the home tab was the only
 	 * one, a window that came back empty.
@@ -394,10 +393,10 @@ class TabManager {
 	 * `''` for a tab whose file is read afterwards, which is what both callers
 	 * in the app do. It is NOT the rendered `content`: that starts empty here
 	 * as it does at every other construction site (`addNewTab`, `restoreState`,
-	 * `addHomeTab`, `buildTransferredTab`), and the first preview render fills
-	 * it. Seeding it from this argument put Markdown in the field that is
-	 * injected via `{@html}` — sanitized at the sink, so it showed as escaped
-	 * source rather than being a hole, but it is not what that field means.
+	 * `buildTransferredTab`), and the first preview render fills it. Seeding it
+	 * from this argument put Markdown in the field that is injected via
+	 * `{@html}` — sanitized at the sink, so it showed as escaped source rather
+	 * than being a hole, but it is not what that field means.
 	 */
 	addTab(path: string, rawContent: string = '', pathKey?: string) {
 		// Opening a file that is already open activates that tab instead of
@@ -482,40 +481,6 @@ class TabManager {
 		this.activeTabId = id;
 	}
 
-	addHomeTab() {
-		const homeTab = this.tabs.find(t => isHomePath(t.path));
-		if (homeTab) {
-			this.activeTabId = homeTab.id;
-			return;
-		}
-
-		const id = crypto.randomUUID();
-		this.tabs.push({
-			id,
-			path: HOME_TAB_PATH,
-			title: t('tabs.home', settings.language),
-			content: '',
-			rawContent: '',
-			originalContent: '',
-			scrollTop: 0,
-			isDirty: false,
-			isEditing: false,
-			history: [],
-			historyIndex: 0,
-			editorViewState: null,
-			scrollPercentage: 0,
-			anchorLine: 0,
-			isSplit: false,
-			splitRatio: 0.5,
-			isScrollSynced: false,
-			collapsedHeaders: new Set<string>(),
-			isTruncated: false,
-			hasReplacementChars: false
-		});
-
-		this.activeTabId = id;
-	}
-
 	/**
 	 * Insert a tab that arrived from another window (cross-window transfer).
 	 * The snapshot carries the unsaved buffer — see tabTransfer.ts. Rendered

src/lib/utils/homeTab.ts

@@ -14,6 +14,20 @@
  * A tab kind is not really a path, and nothing stops a document from being
  * opened at a relative path spelled exactly `HOME`. Neither is fixed here, but
  * both are now a single edit rather than a search-and-replace.
+ *
+ * Nothing in the app constructs such a tab any more. `TabManager.addHomeTab`
+ * was the only constructor, its only caller was the Ctrl+T branch in
+ * MarkdownViewer.svelte, and that branch now opens a new file instead (#480) —
+ * so the method went with it.
+ *
+ * The sentinel and its reader stay, because a tab carrying it can still arrive
+ * from outside this build. Snapshots written before #401 have `HOME` in them
+ * and are sitting on users' disks; what turns those away is `hasRealFilePath`
+ * in tabFileActions.ts, and that predicate is spelled in terms of `isHomePath`.
+ * The recognition IS the rejection — drop it and the sentinel is readmitted as
+ * a phantom tab pointing at a file that can never be read (#401). The gate in
+ * MarkdownViewer.svelte and the tab-strip guards keep reading it for the same
+ * reason: they are what a stray home tab would run into (#429).
  */
 export const HOME_TAB_PATH = 'HOME';