diff --git a/scripts/lib/skill-evolution/versioning.js b/scripts/lib/skill-evolution/versioning.js
index 307fa599f..32bc83858 100644
--- a/scripts/lib/skill-evolution/versioning.js
+++ b/scripts/lib/skill-evolution/versioning.js
@@ -83,7 +83,8 @@ function parseVersionNumber(fileName) {
     return null;
   }
 
-  return Number(match[1]);
+  const version = Number(match[1]);
+  return Number.isSafeInteger(version) && version >= 1 ? version : null;
 }
 
 function listVersions(skillPath) {
@@ -170,16 +171,19 @@ function getEvolutionLog(skillPath, logType) {
 
 function createVersion(skillPath, options = {}) {
   const skillFilePath = ensureSkillExists(skillPath);
-  ensureSkillVersioning(skillPath);
 
   const versions = listVersions(skillPath);
   const versionsDir = getVersionsDir(skillPath);
-  const occupiedPaths = new Set(fs.readdirSync(versionsDir));
+  const occupiedPaths = new Set(fs.existsSync(versionsDir) ? fs.readdirSync(versionsDir) : []);
   let nextVersion = versions.length === 0 ? 1 : versions[versions.length - 1].version + 1;
   // Listing excludes non-files, but their paths remain user-owned and occupied.
-  while (occupiedPaths.has(`v${nextVersion}.md`)) {
+  while (Number.isSafeInteger(nextVersion) && occupiedPaths.has(`v${nextVersion}.md`)) {
     nextVersion += 1;
   }
+  if (!Number.isSafeInteger(nextVersion)) {
+    throw new Error('Skill snapshot version range is exhausted; existing snapshots were preserved');
+  }
+  ensureSkillVersioning(skillPath);
   const snapshotPath = path.join(versionsDir, `v${nextVersion}.md`);
   const skillContent = fs.readFileSync(skillFilePath, 'utf8');
   const createdAt = options.timestamp || new Date().toISOString();
diff --git a/tests/lib/skill-evolution-storage.test.js b/tests/lib/skill-evolution-storage.test.js
index 4b070ba06..8cc7a8a1b 100644
--- a/tests/lib/skill-evolution-storage.test.js
+++ b/tests/lib/skill-evolution-storage.test.js
@@ -66,5 +66,41 @@ test('health skips malformed amendment rows while retaining a valid pending prop
   assert.equal(report.skills.find(skill => skill.skill_id === 'demo').pending_amendments, 1);
 });
 
+test('snapshot allocation ignores invalid numeric names and preserves their contents', fixture => {
+  const { skillDir, versionsDir } = fixture;
+  fs.mkdirSync(versionsDir);
+  const names = ['v0.md', 'v9007199254740992.md', `v${'9'.repeat(80)}.md`];
+  for (const name of names) fs.writeFileSync(path.join(versionsDir, name), 'preserve');
+  assert.deepEqual(versioning.listVersions(skillDir), []);
+  const snapshot = versioning.createVersion(skillDir);
+  assert.equal(snapshot.version, 1);
+  assert.equal(fs.readFileSync(snapshot.path, 'utf8'), '# Original\n');
+  for (const name of names) assert.equal(fs.readFileSync(path.join(versionsDir, name), 'utf8'), 'preserve');
+});
+
+test('exhausted snapshot numbering refuses creation before initializing evolution logs', fixture => {
+  const { skillDir, versionsDir } = fixture;
+  fs.mkdirSync(versionsDir);
+  const last = path.join(versionsDir, `v${Number.MAX_SAFE_INTEGER}.md`);
+  fs.writeFileSync(last, 'preserve');
+  assert.throws(() => versioning.createVersion(skillDir), /snapshot version range is exhausted/);
+  assert.deepEqual(fs.readdirSync(versionsDir), [`v${Number.MAX_SAFE_INTEGER}.md`]);
+  assert.equal(fs.readFileSync(last, 'utf8'), 'preserve');
+  assert.equal(fs.existsSync(versioning.getEvolutionDir(skillDir)), false);
+});
+
+test('an occupied final safe snapshot path refuses creation while preserving the directory', fixture => {
+  const { skillDir, versionsDir } = fixture;
+  fs.mkdirSync(versionsDir);
+  fs.writeFileSync(path.join(versionsDir, `v${Number.MAX_SAFE_INTEGER - 1}.md`), 'preserve');
+  const occupied = path.join(versionsDir, `v${Number.MAX_SAFE_INTEGER}.md`);
+  fs.mkdirSync(occupied);
+  fs.writeFileSync(path.join(occupied, 'keep.txt'), 'preserve');
+  assert.throws(() => versioning.createVersion(skillDir), /snapshot version range is exhausted/);
+  assert.equal(fs.readdirSync(versionsDir).length, 2);
+  assert.equal(fs.readFileSync(path.join(occupied, 'keep.txt'), 'utf8'), 'preserve');
+  assert.equal(fs.existsSync(versioning.getEvolutionDir(skillDir)), false);
+});
+
 console.log(`Results: Passed: ${passed}, Failed: ${failed}`);
 process.exitCode = failed > 0 ? 1 : 0;