diff --git a/.github/workflows/test-ops-scripts.yml b/.github/workflows/test-ops-scripts.yml
index 3c6488fa..a6f342e1 100644
--- a/.github/workflows/test-ops-scripts.yml
+++ b/.github/workflows/test-ops-scripts.yml
@@ -1,19 +1,25 @@
 name: Ops Scripts Tests
 
-# Runs the unittest suite for scripts/ops/ on every PR + push that touches
-# the directory. Kept separate from the main CI so a script-only change
-# doesn't trigger the heavier Go/Canvas/Python pipelines.
+# Runs the unittest suite for scripts/ on every PR + push that touches
+# anything under scripts/. Kept separate from the main CI so a script-only
+# change doesn't trigger the heavier Go/Canvas/Python pipelines.
+#
+# Discovery: `unittest discover` from the scripts/ root walks recursively,
+# so both `scripts/test_*.py` and `scripts/ops/test_*.py` are picked up.
+# Tests should sit alongside the code they test (see
+# scripts/ops/test_sweep_cf_decide.py for the pattern; scripts/
+# test_build_runtime_package.py for the rewriter coverage).
 
 on:
   push:
     branches: [main, staging]
     paths:
-      - 'scripts/ops/**'
+      - 'scripts/**'
       - '.github/workflows/test-ops-scripts.yml'
   pull_request:
     branches: [main, staging]
     paths:
-      - 'scripts/ops/**'
+      - 'scripts/**'
       - '.github/workflows/test-ops-scripts.yml'
   merge_group:
     types: [checks_requested]
@@ -31,6 +37,14 @@ jobs:
       - uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
         with:
           python-version: '3.11'
-      - name: Run unittest
+      - name: Run scripts/ unittests (build_runtime_package, …)
+        # Top-level scripts/ tests live alongside their target file
+        # (e.g. scripts/test_build_runtime_package.py exercises
+        # scripts/build_runtime_package.py). discover from scripts/
+        # picks up only top-level test_*.py because scripts/ops/ has
+        # no __init__.py — that's intentional, so we run two passes.
+        working-directory: scripts
+        run: python -m unittest discover -t . -p 'test_*.py' -v
+      - name: Run scripts/ops/ unittests (sweep_cf_decide, …)
         working-directory: scripts/ops
         run: python -m unittest discover -p 'test_*.py' -v
diff --git a/scripts/test_build_runtime_package.py b/scripts/test_build_runtime_package.py
new file mode 100644
index 00000000..ec57b5e2
--- /dev/null
+++ b/scripts/test_build_runtime_package.py
@@ -0,0 +1,201 @@
+"""Tests for scripts/build_runtime_package.py — the wheel-build import rewriter.
+
+Run locally: ``python3 -m unittest scripts/test_build_runtime_package.py -v``
+
+Why this exists: PR #2433 shipped ``import inbox as _inbox_module`` inside
+the workspace runtime, and the rewriter expanded it to
+``import molecule_runtime.inbox as inbox as _inbox_module`` — invalid
+Python. The wheel-smoke gate caught it post-merge but couldn't block
+the merge (not a required check yet — see PR #2439). PR #2436 added a
+build-time gate that raises ``ValueError`` on this pattern; this file
+locks the rewriter's documented contract under unit test so the gate
+itself can't silently regress.
+
+Coverage:
+- ``import X``                  → ``import molecule_runtime.X as X``
+- ``import X.sub``              → ``import molecule_runtime.X.sub``
+- ``import X``  + trailing comment is preserved
+- ``from X import Y``           → ``from molecule_runtime.X import Y``
+- ``from X.sub import Y``       → ``from molecule_runtime.X.sub import Y``
+- ``from X import Y, Z``        → ``from molecule_runtime.X import Y, Z``
+- ``import X as Y``             → raises ValueError (the rewriter would
+  produce ``import molecule_runtime.X as X as Y``, syntax error)
+- non-allowlist module names    → not rewritten (regex anchors on the closed set)
+- Indented imports (inside def/class) keep their indentation.
+"""
+from __future__ import annotations
+
+import os
+import sys
+import unittest
+
+# scripts/build_runtime_package.py lives at scripts/ — add scripts/ to sys.path
+# so the import works whether unittest is invoked from repo root or scripts/.
+HERE = os.path.dirname(os.path.abspath(__file__))
+if HERE not in sys.path:
+    sys.path.insert(0, HERE)
+
+import build_runtime_package as M  # noqa: E402
+
+
+def rewrite(text: str) -> str:
+    """Run the rewriter end-to-end so the test exercises the same path
+    used by the wheel build (regex compile + substitution)."""
+    regex = M.build_import_rewriter()
+    return M.rewrite_imports(text, regex)
+
+
+class TestBareImportRewriting(unittest.TestCase):
+    def test_plain_import_aliases_to_preserve_binding(self):
+        self.assertEqual(
+            rewrite("import inbox\n"),
+            "import molecule_runtime.inbox as inbox\n",
+        )
+
+    def test_plain_import_with_trailing_comment_is_preserved(self):
+        # Real-world shape from a2a_mcp_server.py — the comment must
+        # survive the rewrite without losing its leading-space buffer.
+        self.assertEqual(
+            rewrite("import inbox  # noqa: E402\n"),
+            "import molecule_runtime.inbox as inbox  # noqa: E402\n",
+        )
+
+    def test_import_dotted_keeps_dotted_form(self):
+        # `import X.sub` is rare for our modules but the rewriter must
+        # not double-alias — we want `import molecule_runtime.X.sub`,
+        # not `import molecule_runtime.X.sub as X.sub` (invalid).
+        self.assertEqual(
+            rewrite("import platform_tools.registry\n"),
+            "import molecule_runtime.platform_tools.registry\n",
+        )
+
+    def test_indented_import_preserves_indentation(self):
+        src = "def foo():\n    import inbox\n    return inbox.x\n"
+        out = rewrite(src)
+        self.assertIn("    import molecule_runtime.inbox as inbox\n", out)
+
+
+class TestFromImportRewriting(unittest.TestCase):
+    def test_from_module_import_simple(self):
+        self.assertEqual(
+            rewrite("from inbox import InboxState\n"),
+            "from molecule_runtime.inbox import InboxState\n",
+        )
+
+    def test_from_dotted_import(self):
+        self.assertEqual(
+            rewrite("from platform_tools.registry import TOOLS\n"),
+            "from molecule_runtime.platform_tools.registry import TOOLS\n",
+        )
+
+    def test_from_import_multiple_symbols(self):
+        # Multi-import statement — the rewriter only touches the module
+        # prefix, not the names being imported.
+        self.assertEqual(
+            rewrite("from a2a_tools import (foo, bar, baz)\n"),
+            "from molecule_runtime.a2a_tools import (foo, bar, baz)\n",
+        )
+
+    def test_from_import_block_form(self):
+        src = (
+            "from a2a_tools import (\n"
+            "    tool_check_task_status,\n"
+            "    tool_commit_memory,\n"
+            ")\n"
+        )
+        out = rewrite(src)
+        self.assertIn("from molecule_runtime.a2a_tools import (\n", out)
+        # Trailing names + closer are unchanged.
+        self.assertIn("    tool_check_task_status,\n", out)
+        self.assertIn(")\n", out)
+
+
+class TestImportAsAliasRejection(unittest.TestCase):
+    """The key regression class — the failure mode that shipped in PR #2433."""
+
+    def test_import_as_alias_raises_value_error(self):
+        with self.assertRaises(ValueError) as ctx:
+            rewrite("import inbox as _inbox_module\n")
+        msg = str(ctx.exception)
+        # Error must name the offending module + suggest the fix.
+        self.assertIn("inbox", msg)
+        self.assertIn("as <alias>", msg)
+        self.assertIn("from", msg)  # suggests `from X import …`
+
+    def test_import_as_alias_indented_still_rejected(self):
+        # Indented (inside def/class) — same hazard, same rejection.
+        with self.assertRaises(ValueError):
+            rewrite("def foo():\n    import inbox as _x\n")
+
+    def test_import_as_alias_with_trailing_comment_still_rejected(self):
+        with self.assertRaises(ValueError):
+            rewrite("import inbox as _x  # comment\n")
+
+    def test_plain_import_with_as_in_comment_does_not_trip(self):
+        # The detection strips comments before pattern-matching, so a
+        # comment containing "as foo" must NOT trigger the rejection.
+        self.assertEqual(
+            rewrite("import inbox  # rewriter produces alias as inbox\n"),
+            "import molecule_runtime.inbox as inbox  # rewriter produces alias as inbox\n",
+        )
+
+    def test_import_followed_by_comma_is_not_an_alias(self):
+        # `import inbox, os` — comma is not `as`, must not be rejected.
+        # Our regex captures `inbox` then `,` — only `inbox` gets prefixed.
+        # `os` is not in TOP_LEVEL_MODULES so it's left alone.
+        out = rewrite("import inbox, os\n")
+        # The first module is rewritten; the second (non-allowlist) is not.
+        self.assertIn("import molecule_runtime.inbox as inbox", out)
+
+
+class TestOutsideAllowlistModules(unittest.TestCase):
+    def test_third_party_imports_unchanged(self):
+        # `httpx`, `os`, `re` etc. are not in TOP_LEVEL_MODULES — the
+        # regex must not match them. This is the closed-list invariant
+        # that prevents accidental rewrites of stdlib / third-party.
+        src = "import httpx\nimport os\nfrom re import match\n"
+        self.assertEqual(rewrite(src), src)
+
+    def test_short_name_collision_avoided(self):
+        # `from a2a.server.X import Y` must not match the bare `a2a`
+        # prefix — `a2a` isn't in our allowlist (we allow `a2a_tools`,
+        # `a2a_client`, etc., but not bare `a2a`). Belt-and-suspenders.
+        src = "from a2a.server.routes import create_agent_card_routes\n"
+        self.assertEqual(rewrite(src), src)
+
+
+class TestEndToEndShape(unittest.TestCase):
+    """Reproduces the PR #2433 → #2436 incident shape."""
+
+    def test_pr_2433_pattern_now_rejected(self):
+        # The exact line PR #2433 added (inside main()), which produced
+        # `import molecule_runtime.inbox as inbox as _inbox_module` —
+        # invalid syntax in the published wheel.
+        with self.assertRaises(ValueError) as ctx:
+            rewrite(
+                "    import inbox as _inbox_module\n"
+                "    _inbox_module.set_notification_callback(_on_inbox_message)\n"
+            )
+        # Error message includes the offending line so the operator
+        # knows exactly where to fix.
+        self.assertIn("inbox", str(ctx.exception))
+
+    def test_pr_2436_fix_pattern_works(self):
+        # The fix-forward shape (#2436): top-level `import inbox`,
+        # bridge wired in main() via `inbox.set_notification_callback`.
+        src = (
+            "import inbox\n"
+            "\n"
+            "def main():\n"
+            "    inbox.set_notification_callback(cb)\n"
+        )
+        out = rewrite(src)
+        self.assertIn("import molecule_runtime.inbox as inbox\n", out)
+        # The callable reference inside main() is left alone — only
+        # imports get rewritten, not arbitrary `inbox.foo` callsites
+        # (those resolve via the module binding the rewrite preserves).
+        self.assertIn("    inbox.set_notification_callback(cb)\n", out)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/workspace/a2a_mcp_server.py b/workspace/a2a_mcp_server.py
index 09512f26..b3255bf0 100644
--- a/workspace/a2a_mcp_server.py
+++ b/workspace/a2a_mcp_server.py
@@ -17,9 +17,11 @@ import json
 import logging
 import sys
 
-import inbox  # noqa: F401  — bridge wiring lives in main(); the rewriter
-#                              produces `import molecule_runtime.inbox as inbox`
-#                              which preserves this binding for set_notification_callback.
+# Top-level (not inside main()) so the wheel rewriter expands this to
+# `import molecule_runtime.inbox as inbox`. A local `import inbox as _x`
+# would expand to `import molecule_runtime.inbox as inbox as _x`,
+# which is invalid — see scripts/build_runtime_package.py:rewrite_imports.
+import inbox
 
 from a2a_tools import (
     tool_check_task_status,