fix: the file-name preview stops promising names Obsidian will refuse

src/formatters/displayFormatters-1579-field-placeholder.test.ts

@@ -0,0 +1,68 @@
+import { describe, expect, it } from "vitest";
+import type { App } from "obsidian";
+import { FileNameDisplayFormatter } from "./fileNameDisplayFormatter";
+import { FormatDisplayFormatter } from "./formatDisplayFormatter";
+import type QuickAdd from "../main";
+
+/**
+ * Issue #1579. Both preview formatters built the `{{FIELD:...}}` placeholder out
+ * of the token's WHOLE inner text, filters included, so the more precisely you
+ * filtered the less the preview looked like a value:
+ * `{{FIELD:status|folder:Work}}` previewed `status|folder:Work_field_value`.
+ * The field is `status`.
+ */
+const mockApp = {
+	workspace: { getActiveFile: () => null },
+	vault: { getMarkdownFiles: () => [], getAbstractFileByPath: () => null },
+	metadataCache: { getFileCache: () => null, getAllPropertyInfos: () => ({}) },
+} as unknown as App;
+
+const plugin = {
+	settings: { globalVariables: {}, choices: [] },
+	getTemplateFiles: () => [],
+} as unknown as QuickAdd;
+
+const formatters = [
+	["file name", () => new FileNameDisplayFormatter(mockApp, plugin)],
+	["format", () => new FormatDisplayFormatter(mockApp, plugin)],
+] as const;
+
+describe.each(formatters)("the %s preview names the FIELD", (_label, make) => {
+	it.each([
+		["no filters", "{{FIELD:status}}", "status_field_value"],
+		["one filter", "{{FIELD:status|folder:Work}}", "status_field_value"],
+		[
+			"several filters",
+			"{{FIELD:status|folder:Work|exclude-tag:archive|multi}}",
+			"status_field_value",
+		],
+		// Not a case: `{{FIELD:status,Work}}` previews `status,Work_field_value`,
+		// and that is faithful - FieldSuggestionParser splits on `|` only, so the
+		// run looks up a property literally named "status,Work" too.
+	])("%s", async (_case, input, expected) => {
+		expect(await make().format(input)).toBe(expected);
+	});
+
+	it("says something neutral when the field name is missing", async () => {
+		// Reachable on every keystroke of `{{FIELD:|folder:x}}`. Echoing the raw
+		// specifier back here would reprint the filters, which is the bug.
+		expect(await make().format("{{FIELD:|folder:Work}}")).toBe("field_value");
+	});
+});
+
+describe("#1579 the variable KEY still carries the whole specifier", () => {
+	it("keeps two differently filtered {{FIELD:status}} tokens apart", async () => {
+		// They are different prompts at run time, so they must not collapse onto
+		// one variable - even though they now PREVIEW identically.
+		const formatter = new FileNameDisplayFormatter(mockApp, plugin);
+		await formatter.format("{{FIELD:status|folder:Work}} {{FIELD:status}}");
+
+		const keys = [
+			...(formatter as unknown as { variables: Map<string, unknown> }).variables.keys(),
+		];
+		expect(keys).toEqual([
+			"FIELD:status|folder:Work",
+			"FIELD:status",
+		]);
+	});
+});

src/formatters/fileNameDisplayFormatter-1563-normalize.test.ts

@@ -57,6 +57,7 @@ describe("the file-name preview mirrors the run's name normalizer", () => {
 		expect(problems).toEqual([
 			{
 				severity: "error",
+				kind: "path",
 				message: 'File path cannot contain "." or ".." path segments.',
 			},
 		]);
@@ -70,6 +71,7 @@ describe("the file-name preview mirrors the run's name normalizer", () => {
 		expect(problems).toEqual([
 			{
 				severity: "error",
+				kind: "path",
 				message: "File path contains an empty path segment after formatting.",
 			},
 		]);
@@ -87,9 +89,31 @@ describe("the file-name preview mirrors the run's name normalizer", () => {
 			"tag:#inbox",
 			"Daily/2026-07-27.md",
 		]) {
-			const { out, problems } = await preview(target);
+			const { out } = await preview(target);
 			expect(out).toBe(target);
-			expect(problems).toEqual([]);
 		}
 	});
+
+	it("does report the colon in a picker target, which the builder hides", async () => {
+		// This formatter previews FILE NAMES. `property:x=y` and `tag:#inbox` are
+		// capture-target syntax, not paths, and a colon in an actual name really
+		// is fatal - so the rule is right and the SURFACE is what knows the
+		// difference: CaptureTargetSetting.svelte renders no preview row at all
+		// while the field holds recognised picker syntax
+		// (`{#if !usesPickerTargetSyntax}`), and that gate is pinned by
+		// CaptureTargetSetting-1578-picker-preview.test.ts.
+		//
+		// Teaching the formatter capture semantics would be the wrong layer: the
+		// same class previews a Template choice's file name, where a literal
+		// `property:x=y` IS a path and the colon IS the problem.
+		const { problems } = await preview("property:status=done");
+		expect(problems).toEqual([
+			{
+				severity: "error",
+				kind: "path",
+				message:
+					'A file or folder name cannot contain ":", so this choice would fail at run time. Check your own text and tokens like {{TIME}}, which is HH:mm.',
+			},
+		]);
+	});
 });

src/formatters/fileNameDisplayFormatter-1563-template.test.ts

@@ -146,6 +146,14 @@ describe("#1563 the file-name preview resolves {{TEMPLATE:}}", () => {
 				message:
 					'Template "Body.md" is 5 lines; a file name is one line, so they are joined with spaces.',
 			},
+			{
+				// The frontmatter's "title: x" is now IN the name, so the name has a
+				// colon in it and Obsidian would refuse it (#1578).
+				severity: "error",
+				kind: "path",
+				message:
+					'A file or folder name cannot contain ":", so this choice would fail at run time. Check your own text and tokens like {{TIME}}, which is HH:mm.',
+			},
 		]);
 	});