diff --git a/app/composables/query-state.ts b/app/composables/query-state.ts
index 881b938..2b8606b 100644
--- a/app/composables/query-state.ts
+++ b/app/composables/query-state.ts
@@ -56,10 +56,15 @@ export function asOneOf<T extends string>(options: readonly T[]) {
 
 export const asRange = {
   parse: (raw: string): [number, number] => {
-    const [lo, hi] = raw.split('-').map(Number)
-    if (lo === undefined || hi === undefined) throw new Error('bad range')
-    if (!Number.isFinite(lo) || !Number.isFinite(hi))
+    const [loRaw, hiRaw, extra] = raw.split('-', 3)
+    if (!loRaw?.trim() || !hiRaw?.trim() || extra !== undefined)
       throw new Error('bad range')
+
+    const lo = Number(loRaw)
+    const hi = Number(hiRaw)
+    if (!Number.isFinite(lo) || !Number.isFinite(hi) || lo > hi)
+      throw new Error('bad range')
+
     return [lo, hi]
   },
   serialize: ([lo, hi]: [number, number]) => `${lo}-${hi}`,
diff --git a/scripts/tests/query-state.test.ts b/scripts/tests/query-state.test.ts
new file mode 100644
index 0000000..7f849bf
--- /dev/null
+++ b/scripts/tests/query-state.test.ts
@@ -0,0 +1,27 @@
+import { describe, expect, it } from 'vitest'
+import { asRange } from '../../app/composables/query-state.ts'
+
+describe('stroke range query parsing', () => {
+  it.each([
+    ['1-36', [1, 36]],
+    ['10-10', [10, 10]],
+  ])('accepts %s', (raw, expected) => {
+    expect(asRange.parse(raw)).toEqual(expected)
+  })
+
+  it.each([
+    // Reversed bounds would match nothing yet read as a legitimate empty table.
+    '20-10',
+    // A third segment would otherwise be dropped without a trace.
+    '1-2-3',
+    'x-10',
+    '10-x',
+    // Number('') is 0, so an empty segment must be rejected before conversion.
+    '-10',
+    '10-',
+    '0-',
+    '-',
+  ])('rejects %s so the query falls back to the default', (raw) => {
+    expect(() => asRange.parse(raw)).toThrow()
+  })
+})