test: add regression test for pre-execution backtick strip and inputs-only check

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/resources/extensions/gsd/tests/pre-exec-backtick-strip.test.ts

@@ -0,0 +1,68 @@
+/**
+ * Regression test for #3626 / #3649 — pre-execution-checks false positives
+ *
+ * Two sources of false positives were fixed:
+ *   1. normalizeFilePath did not strip backtick wrapping from LLM-generated
+ *      paths like `src/foo.ts`, causing file-existence checks to fail (#3649).
+ *   2. checkFilePathConsistency checked both task.files and task.inputs, but
+ *      task.files ("files likely touched") intentionally includes files that
+ *      will be created by the task, so they don't need to pre-exist (#3626).
+ */
+
+import { describe, it } from 'node:test'
+import assert from 'node:assert/strict'
+import { normalizeFilePath, checkFilePathConsistency } from '../pre-execution-checks.ts'
+import { readFileSync } from 'node:fs'
+import { resolve } from 'node:path'
+
+const src = readFileSync(
+  resolve(process.cwd(), 'src', 'resources', 'extensions', 'gsd', 'pre-execution-checks.ts'),
+  'utf-8',
+)
+
+describe('normalizeFilePath backtick stripping (#3649)', () => {
+  it('strips backticks from file paths', () => {
+    assert.equal(normalizeFilePath('`src/foo.ts`'), 'src/foo.ts')
+  })
+
+  it('strips backticks even when mixed with other normalization', () => {
+    assert.equal(normalizeFilePath('`./src//bar.ts`'), 'src/bar.ts')
+  })
+
+  it('leaves normal paths unchanged', () => {
+    assert.equal(normalizeFilePath('src/foo.ts'), 'src/foo.ts')
+  })
+
+  it('handles empty string', () => {
+    assert.equal(normalizeFilePath(''), '')
+  })
+})
+
+describe('checkFilePathConsistency checks task.inputs not task.files (#3626)', () => {
+  it('source uses only task.inputs in filesToCheck', () => {
+    // Verify the fix structurally: the spread should be [...task.inputs] only
+    const fnStart = src.indexOf('export function checkFilePathConsistency(')
+    assert.ok(fnStart !== -1, 'checkFilePathConsistency function must exist')
+
+    // Find the filesToCheck assignment
+    const filesToCheckLine = src.indexOf('filesToCheck', fnStart)
+    assert.ok(filesToCheckLine !== -1, 'filesToCheck assignment must exist')
+
+    // Extract the line
+    const lineEnd = src.indexOf('\n', filesToCheckLine)
+    const line = src.slice(filesToCheckLine, lineEnd)
+
+    // Must include task.inputs
+    assert.ok(
+      line.includes('task.inputs'),
+      'filesToCheck must reference task.inputs',
+    )
+
+    // Must NOT include task.files
+    assert.ok(
+      !line.includes('task.files'),
+      'filesToCheck must NOT reference task.files — files likely touched include ' +
+        'files the task will create, so they do not need to pre-exist',
+    )
+  })
+})