@@ -11,6 +11,12 @@ function parseDateArg(value: string): string {
 	return v.parse(filterDateSchema, value);
 }
 
+/**
+ * Shared date-range CLI flags for OpenCode reports.
+ *
+ * Both `since` and `until` accept `YYYYMMDD` strings and use `parseDateArg`
+ * for the same format validation before satisfying Gunshi's `Args` shape.
+ */
 export const dateFilterArgs = {
 	since: {
 		type: 'custom',
@@ -25,3 +31,25 @@ export const dateFilterArgs = {
 		parse: parseDateArg,
 	},
 } as const satisfies Args;
+
+if (import.meta.vitest != null) {
+	const { describe, expect, it } = import.meta.vitest;
+
+	describe('dateFilterArgs', () => {
+		it('should parse main-mode compatible since and until args', () => {
+			expect(dateFilterArgs.since.short).toBe('s');
+			expect(dateFilterArgs.since.description).toBe('Filter from date (YYYYMMDD format)');
+			expect(dateFilterArgs.since.parse('20240102')).toBe('20240102');
+			expect(() => dateFilterArgs.since.parse('2024-01-02')).toThrow(
+				'Date must be in YYYYMMDD format',
+			);
+
+			expect(dateFilterArgs.until.short).toBe('u');
+			expect(dateFilterArgs.until.description).toBe('Filter until date (YYYYMMDD format)');
+			expect(dateFilterArgs.until.parse('20240103')).toBe('20240103');
+			expect(() => dateFilterArgs.until.parse('2024-01-03')).toThrow(
+				'Date must be in YYYYMMDD format',
+			);
+		});
+	});
+}
@@ -1,20 +1,18 @@
+import { dateFilterArgs } from '../_shared-args.ts';
 import { dailyCommand } from './daily.ts';
 import { monthlyCommand } from './monthly.ts';
 import { sessionCommand } from './session.ts';
 import { weeklyCommand } from './weekly.ts';
 
-export { dailyCommand } from './daily.ts';
-export { monthlyCommand } from './monthly.ts';
-export { sessionCommand } from './session.ts';
-export { weeklyCommand } from './weekly.ts';
+export { dailyCommand, monthlyCommand, sessionCommand, weeklyCommand };
 
 if (import.meta.vitest != null) {
 	const { describe, expect, it } = import.meta.vitest;
 
 	type DateArg = {
-		short: string;
-		description: string;
-		parse: (value: string) => string;
+		readonly short: string;
+		readonly description: string;
+		readonly parse: (value: string) => string;
 	};
 	type CommandWithDateArgs = {
 		args: {
@@ -29,18 +27,11 @@ if (import.meta.vitest != null) {
 			['weekly', weeklyCommand],
 			['monthly', monthlyCommand],
 			['session', sessionCommand],
-		])('should expose main-mode compatible since and until args for %s', (_name, command) => {
+		])('should expose shared since and until args for %s', (_name, command) => {
 			const args = (command as CommandWithDateArgs).args;
 
-			expect(args.since?.short).toBe('s');
-			expect(args.since?.description).toBe('Filter from date (YYYYMMDD format)');
-			expect(args.since?.parse('20240102')).toBe('20240102');
-			expect(() => args.since?.parse('2024-01-02')).toThrow('Date must be in YYYYMMDD format');
-
-			expect(args.until?.short).toBe('u');
-			expect(args.until?.description).toBe('Filter until date (YYYYMMDD format)');
-			expect(args.until?.parse('20240103')).toBe('20240103');
-			expect(() => args.until?.parse('2024-01-03')).toThrow('Date must be in YYYYMMDD format');
+			expect(args.since).toBe(dateFilterArgs.since);
+			expect(args.until).toBe(dateFilterArgs.until);
 		});
 	});
 }
@@ -123,6 +123,12 @@ export type LoadedSessionMetadata = {
 	directory: string;
 };
 
+/**
+ * Date range options for loading OpenCode messages.
+ *
+ * `since` and `until` use `YYYYMMDD` strings so the loader can apply the same
+ * lexicographic date comparison semantics as the main CLI.
+ */
 export type LoadOpenCodeMessagesOptions = {
 	since?: string;
 	until?: string;
@@ -499,5 +505,26 @@ if (import.meta.vitest != null) {
 				await rm(root, { recursive: true, force: true });
 			}
 		});
+
+		it('should return no OpenCode messages for non-overlapping date ranges', async () => {
+			const root = await createOpenCodeMessageFixture([
+				createTestMessage('msg_20240101', '2024-01-01T12:00:00.000Z'),
+				createTestMessage('msg_20240102', '2024-01-02T12:00:00.000Z'),
+				createTestMessage('msg_20240103', '2024-01-03T12:00:00.000Z'),
+			]);
+
+			try {
+				vi.stubEnv(OPENCODE_CONFIG_DIR_ENV, root);
+
+				const entries = await loadOpenCodeMessages({
+					since: '20240104',
+					until: '20240105',
+				});
+
+				expect(getSortedIsoTimestamps(entries)).toEqual([]);
+			} finally {
+				await rm(root, { recursive: true, force: true });
+			}
+		});
 	});
 }