fix calendar time label axis width

docs/releases/unreleased.md

@@ -26,6 +26,8 @@ Example:
 
 ## Fixed
 
+- (#1898) Fixed Calendar Day view time labels shifting into the middle of the grid after switching views.
+  - Thanks to @ddevaal for reporting and confirming the regression.
 - (#1916) Fixed Markdown task links using Obsidian's generated filename label instead of the TaskNote title in the task link overlay.
   - Thanks to @minchinweb for reporting.
 - (#1911) Fixed recurrence choices starting from today instead of the selected calendar date when creating a task from Calendar view.

styles/advanced-calendar-view.css

@@ -1081,6 +1081,7 @@
     color: var(--text-muted);
     padding: 0;
     text-align: right;
+    width: 4rem;
 }
 
 .advanced-calendar-view .fc-timegrid-slot-label-frame {

tests/unit/issues/issue-1898-calendar-time-label-axis-width.test.ts

@@ -0,0 +1,39 @@
+/**
+ * Issue #1898: Calendar view time labels shifted to the center.
+ *
+ * The stale inline-width reset for FullCalendar slot labels must be paired with
+ * a fixed slot-label cell width. Without that CSS width, Day view can let the
+ * slot-label column expand to half of the calendar grid after the reset.
+ */
+
+import { describe, expect, it } from "@jest/globals";
+import fs from "fs";
+import path from "path";
+
+const repoRoot = path.resolve(__dirname, "../../..");
+
+function readRepoFile(relativePath: string): string {
+	return fs.readFileSync(path.join(repoRoot, relativePath), "utf-8");
+}
+
+function extractCssBlock(css: string, selector: string): string {
+	const escapedSelector = selector.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
+	const match = css.match(new RegExp(`${escapedSelector}\\s*\\{([^}]*)\\}`));
+	return match?.[1] ?? "";
+}
+
+describe("Issue #1898: Calendar time labels stay anchored to the axis", () => {
+	it("keeps reset slot labels on a fixed time-axis width", () => {
+		const source = readRepoFile("src/bases/CalendarView.ts");
+		const css = readRepoFile("styles/advanced-calendar-view.css");
+
+		const slotLabelBlock = extractCssBlock(
+			css,
+			".advanced-calendar-view .fc-timegrid-slot-label"
+		);
+
+		expect(source).toContain(".fc-timegrid-slot-label");
+		expect(slotLabelBlock).toContain("width: 4rem;");
+		expect(slotLabelBlock).toContain("text-align: right;");
+	});
+});