Use canonical builder source hash

tests/test_template_init.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 import asyncio
-import hashlib
+import gzip
 import io
 import json
 import tarfile
@@ -22,6 +22,7 @@ from agent_builder.tools import (
     _replace_workspace_files,
     _render_a2a_init_template,
     _render_skill_md,
+    _source_bundle_hash,
     _tarball_workspace_dir,
     ToolContext,
     build_tools,
@@ -382,9 +383,9 @@ class TemplateInitTests(unittest.TestCase):
         }
         for rel, content in files.items():
             workspace.write_bytes(prefix + rel, content.encode("utf-8"))
-        source_hash = hashlib.sha256(
+        source_hash = _source_bundle_hash(
             _tarball_workspace_dir(_WorkspaceObjectStore(workspace), prefix)
-        ).hexdigest()
+        )
         workspace.write_bytes(
             prefix + _BUILDER_STATE_FILE,
             json.dumps({
@@ -478,6 +479,27 @@ class TemplateInitTests(unittest.TestCase):
         self.assertEqual(result["error"], "sandbox_not_passed")
         self.assertEqual(_FakeAsyncClient.posts, [])
 
+    def test_source_bundle_hash_ignores_archive_metadata(self) -> None:
+        def bundle_with_mtime(mtime: int) -> bytes:
+            raw = io.BytesIO()
+            with tarfile.open(fileobj=raw, mode="w") as tf:
+                body = b"print('ok')\n"
+                info = tarfile.TarInfo(name="agent.py")
+                info.size = len(body)
+                info.mode = 0o644
+                info.mtime = mtime
+                tf.addfile(info, io.BytesIO(body))
+            compressed = io.BytesIO()
+            with gzip.GzipFile(fileobj=compressed, mode="wb", mtime=mtime) as gz:
+                gz.write(raw.getvalue())
+            return compressed.getvalue()
+
+        first = bundle_with_mtime(1)
+        second = bundle_with_mtime(2)
+
+        self.assertNotEqual(first, second)
+        self.assertEqual(_source_bundle_hash(first), _source_bundle_hash(second))
+
     def test_cp_compose_meta_agent_posts_manifest_and_records_state(self) -> None:
         workspace = _FakeWorkspace()
         tools = build_tools(