diff --git a/layers/registry/server/utils/github-client.ts b/layers/registry/server/utils/github-client.ts
index ef097657..9d0f0dd8 100644
--- a/layers/registry/server/utils/github-client.ts
+++ b/layers/registry/server/utils/github-client.ts
@@ -587,8 +587,15 @@ export async function getTree(
   // into the inventory: sync uses absent paths to retire Skills.
   const rootSha = initial.data.sha
   const incomplete: TreeResponse = { sha: rootSha, tree: [], truncated: true }
+  // The discarded recursive response can hold 100,000 entries. Release it
+  // before reading subtrees, so both inventories never share the working set.
+  initial.data = incomplete
   const pending = [{ sha: rootSha, prefix: '', recursive: false }]
   const entries: TreeEntry[] = []
+  // scienceide_env exhausted Worker memory on five expansion attempts. Bound
+  // retained strings as well as objects; long paths defeat an entry-only cap.
+  const maxRetainedChars = 8 * 1024 * 1024
+  let retainedChars = 0
   let rateLimit = initial.rateLimit
   let requests = 1
   while (pending.length > 0) {
@@ -613,10 +620,13 @@ export async function getTree(
       pending.push({ ...next, recursive: false })
       continue
     }
-    if (entries.length + result.data.tree.length > 250_000)
+    if (entries.length + result.data.tree.length > 100_000)
       return { ...result, data: incomplete, rateLimit, notModified: false }
     for (const entry of result.data.tree) {
       const path = next.prefix ? `${next.prefix}/${entry.path}` : entry.path
+      retainedChars += path.length + entry.sha.length
+      if (retainedChars > maxRetainedChars)
+        return { ...result, data: incomplete, rateLimit, notModified: false }
       entries.push({ path, type: entry.type, sha: entry.sha, size: entry.size })
       if (!next.recursive && entry.type === 'tree')
         pending.push({ sha: entry.sha, prefix: path, recursive: true })
diff --git a/test/unit/github-client-tree.test.ts b/test/unit/github-client-tree.test.ts
index 1cd04e19..3aa9ab38 100644
--- a/test/unit/github-client-tree.test.ts
+++ b/test/unit/github-client-tree.test.ts
@@ -73,4 +73,23 @@ describe('getTree', () => {
     expect(fetchMock.mock.calls.length).toBeGreaterThan(1)
     expect(fetchMock.mock.calls.length).toBeLessThanOrEqual(64)
   })
+
+  it('stops expansion when long paths exceed the retained tree budget', async () => {
+    const subtree = Array.from({ length: 20_000 }, (_, i) => ({
+      path: `${'directory/'.repeat(50)}${i}/SKILL.md`,
+      type: 'blob',
+      sha: 'a'.repeat(40),
+    }))
+    vi.stubGlobal('fetch', vi.fn(async (url: string) => Response.json(
+      url.endsWith('root?recursive=1')
+        ? { sha: 'root', truncated: true, tree: [] }
+        : url.endsWith('root')
+          ? { sha: 'root', tree: [{ path: 'vendor', type: 'tree', sha: 'subtree' }] }
+          : { sha: 'subtree', tree: subtree },
+    )))
+
+    const result = await getTree('acme', 'large', 'root', {}, { expandTruncated: true })
+
+    expect(result.data).toEqual({ sha: 'root', tree: [], truncated: true })
+  })
 })