fix: create missing period folders and explain failures

Clicking a week/month/quarter/year in a vault whose configured folder does
not exist yet failed with a generic 'Failed to create X note: <raw error>',
because vault.create refuses to create parent folders. Create the folder
(and any missing ancestors) first, then report what actually went wrong.

- Every failure path now names the offending path and the reason, and points
  at the relevant settings section; diagnostic notices stay up for 10s.
- A configured-but-missing template used to fall back to basic frontmatter
  silently; the creation notice now says the template was not found.
- The unreachable !date.isValid() branch after detectPeriodType is gone; the
  'not a periodic note' notice now lists the configured formats it expected.

src/main.ts

@@ -5,6 +5,7 @@ import {
 	WorkspaceLeaf,
 	Notice,
 	TFile,
+	TFolder,
 	TAbstractFile,
 	getAllTags,
 	moment,
@@ -527,31 +528,105 @@ export default class WaypointPlugin extends Plugin {
 		if (!file) {
 			file = await this.createPeriodNote(fullPath, periodSettings, date, config.label);
 			if (!file) return;
-			new Notice(`Created ${config.label.toLowerCase()} note: ${filename}`);
 		}
 
 		const target = leaf || this.app.workspace.getLeaf(false);
 		await target.openFile(file);
 	}
 
-	/** Create a period note from its template, or from minimal frontmatter. */
+	/**
+	 * Create a period note from its template, or from minimal frontmatter.
+	 *
+	 * Every failure path names the offending path and the reason: the usual
+	 * cause is a configured folder that does not exist yet, which `vault.create`
+	 * refuses outright rather than creating.
+	 */
 	private async createPeriodNote(
 		fullPath: string,
 		periodSettings: PeriodNoteSettings,
 		date: moment.Moment,
 		label: string,
 	): Promise<TFile | null> {
+		const noun = label.toLowerCase();
+		const slash = fullPath.lastIndexOf('/');
+		const folder = slash < 0 ? '' : fullPath.slice(0, slash);
+
 		try {
-			const templateFile = this.resolveTemplateFile(periodSettings.templateFile);
-			const content = templateFile
-				? await this.app.vault.read(templateFile)
-				: `---\ntype: ${periodSettings.typeProperty}\ndate: ${date.format('YYYY-MM-DD')}\n---\n\n`;
-			return await this.app.vault.create(fullPath, content);
+			await this.ensureFolderExists(folder);
 		} catch (err: unknown) {
-			const message = err instanceof Error ? err.message : String(err);
-			new Notice(`Failed to create ${label.toLowerCase()} note: ${message}`);
+			new Notice(
+				`Waypoint: could not create the folder "${folder}" for the ${noun} note.\n`
+				+ `${describeError(err)}\n`
+				+ 'Check Settings → Waypoint Sidebar → Periodic Notes.',
+				DIAGNOSTIC_NOTICE_MS,
+			);
 			return null;
 		}
+
+		const configuredTemplate = periodSettings.templateFile;
+		const templateFile = this.resolveTemplateFile(configuredTemplate);
+
+		let content: string;
+		if (templateFile) {
+			try {
+				content = await this.app.vault.read(templateFile);
+			} catch (err: unknown) {
+				new Notice(
+					`Waypoint: could not read the template "${templateFile.path}" for the ${noun} note.\n`
+					+ describeError(err),
+					DIAGNOSTIC_NOTICE_MS,
+				);
+				return null;
+			}
+		} else {
+			content = `---\ntype: ${periodSettings.typeProperty}\ndate: ${date.format('YYYY-MM-DD')}\n---\n\n`;
+		}
+
+		let file: TFile;
+		try {
+			file = await this.app.vault.create(fullPath, content);
+		} catch (err: unknown) {
+			new Notice(
+				`Waypoint: could not create the ${noun} note at "${fullPath}".\n${describeError(err)}`,
+				DIAGNOSTIC_NOTICE_MS,
+			);
+			return null;
+		}
+
+		// A configured-but-missing template otherwise fails silently: the note
+		// just appears with the fallback frontmatter and no explanation.
+		if (configuredTemplate && !templateFile) {
+			new Notice(
+				`Created ${noun} note: ${file.basename}\n`
+				+ `Template "${configuredTemplate}" was not found, so a basic note was created instead.`,
+				DIAGNOSTIC_NOTICE_MS,
+			);
+		} else {
+			new Notice(`Created ${noun} note: ${file.basename}`);
+		}
+		return file;
+	}
+
+	/**
+	 * Create `folder` and any missing ancestors.
+	 * `vault.create` throws when the parent folder is absent, so this runs first.
+	 */
+	private async ensureFolderExists(folder: string): Promise<void> {
+		if (!folder) return;
+		if (this.app.vault.getAbstractFileByPath(folder) instanceof TFolder) return;
+
+		let path = '';
+		for (const segment of folder.split('/')) {
+			if (!segment) continue;
+			path = path ? `${path}/${segment}` : segment;
+			if (this.app.vault.getAbstractFileByPath(path) instanceof TFolder) continue;
+			try {
+				await this.app.vault.createFolder(path);
+			} catch (err: unknown) {
+				// Someone else may have created it between the check and the call.
+				if (!(this.app.vault.getAbstractFileByPath(path) instanceof TFolder)) throw err;
+			}
+		}
 	}
 
 	/** The setting may or may not already carry the .md extension. */
@@ -591,17 +666,19 @@ export default class WaypointPlugin extends Plugin {
 
 		const detected = this.detectPeriodType(file.basename);
 		if (!detected) {
-			new Notice('Current file is not a periodic note (daily/weekly/monthly/quarterly/yearly)');
+			const formats = PERIOD_DETECTION_ORDER
+				.map(p => `${PERIOD_CONFIGS[p].label.toLowerCase()} "${this.settings[PERIOD_CONFIGS[p].key].nameFormat}"`)
+				.join(', ');
+			new Notice(
+				`Waypoint: "${file.basename}" does not match any configured periodic note format.\n`
+				+ `Expected one of: ${formats}.`,
+				DIAGNOSTIC_NOTICE_MS,
+			);
 			return;
 		}
 
 		const { period, date } = detected;
 
-		if (!date.isValid()) {
-			new Notice(`Could not parse date from filename: ${file.basename}`);
-			return;
-		}
-
 		const amount = direction === 'next' ? 1 : -1;
 
 		// Map period to moment duration unit
@@ -649,3 +726,10 @@ function basenameFromPath(path: string): string {
 	const name = path.slice(path.lastIndexOf('/') + 1);
 	return name.replace(/\.[^/.]+$/, '');
 }
+
+/** Notices that carry a diagnosis need longer on screen than the default. */
+const DIAGNOSTIC_NOTICE_MS = 10000;
+
+function describeError(err: unknown): string {
+	return err instanceof Error ? err.message : String(err);
+}