diff --git a/products/tasks/backend/constants.py b/products/tasks/backend/constants.py
index be3ea1c1a25e..302d592b8d81 100644
--- a/products/tasks/backend/constants.py
+++ b/products/tasks/backend/constants.py
@@ -290,6 +290,14 @@ def vm_sandbox_allowed_origins(*, distinct_id: str, organization_id: str) -> set
     }
 )
 
+# Stripped from the agent-server's process environment at launch (env -u).
+# Two categories:
+#   - code-injection vectors a resume snapshot could smuggle in (NODE_*, LD_*, DYLD_*);
+#   - the GitHub token, so the agent-server holds no frozen copy of the acting user's
+#     credentials. The token is delivered per command via the live /tmp/agent-env file
+#     (re-sourced by BASH_ENV, seeded before this unset), so git/gh still authenticate;
+#     removing the static process-env copy is what lets a mid-session logout or rebind
+#     actually take effect instead of being resurrected from os.environ.
 SANDBOX_AGENT_LAUNCH_UNSET_ENV_VARS: tuple[str, ...] = (
     "NODE_OPTIONS",
     "NODE_REPL_EXTERNAL_MODULE",
@@ -298,6 +306,8 @@ def vm_sandbox_allowed_origins(*, distinct_id: str, organization_id: str) -> set
     "LD_AUDIT",
     "DYLD_INSERT_LIBRARIES",
     "DYLD_LIBRARY_PATH",
+    "GITHUB_TOKEN",
+    "GH_TOKEN",
 )
 
 
diff --git a/products/tasks/backend/temporal/process_task/sandbox_credentials.py b/products/tasks/backend/temporal/process_task/sandbox_credentials.py
index 81ce5f20e9cd..15d0ed8044a0 100644
--- a/products/tasks/backend/temporal/process_task/sandbox_credentials.py
+++ b/products/tasks/backend/temporal/process_task/sandbox_credentials.py
@@ -19,11 +19,13 @@
     PrAuthorshipMode,
     get_github_token,
     get_pr_authorship_mode,
+    get_sandbox_github_identity_user,
     get_sandbox_github_token,
     get_task_run_credential_user,
     is_caller_token_run,
     is_slack_interaction_state,
     resolve_user_github_integration_for_task,
+    sandbox_identity_scope,
 )
 
 if TYPE_CHECKING:
@@ -159,7 +161,14 @@ def _live_sandboxes_for_user_integration(user_integration_id: int) -> list[tuple
             task__github_user_integration_id=user_integration_id,
         )
         .select_related("task")
-        .only("id", "state", "task__repository", "task__github_user_integration_id", "task__origin_product")
+        .only(
+            "id",
+            "state",
+            "task__repository",
+            "task__github_user_integration_id",
+            "task__origin_product",
+            "task__created_by_id",
+        )
     )
     for run in runs:
         sandbox_id = (run.state or {}).get("sandbox_id")
@@ -172,6 +181,13 @@ def _live_sandboxes_for_user_integration(user_integration_id: int) -> list[tuple
             continue
         if is_caller_token_run(str(run.id), run.state):
             continue
+        # A per-message actor transition may have rebound (or logged out) this sandbox's GitHub
+        # identity to someone other than the run owner. This loop carries the owner's token, so
+        # re-applying it would undo that transition and resurrect the owner's identity for the
+        # current actor. Skip when the sandbox is bound to a different actor.
+        bound_actor = get_sandbox_github_identity_user(sandbox_identity_scope(str(run.id), run.state))
+        if bound_actor is not None and bound_actor != run.task.created_by_id:
+            continue
         rows.append((str(run.id), sandbox_id, run.task.repository))
     return rows
 
diff --git a/products/tasks/backend/temporal/process_task/tests/test_sandbox_credentials.py b/products/tasks/backend/temporal/process_task/tests/test_sandbox_credentials.py
index 014fd645ff43..4457cb9b8bac 100644
--- a/products/tasks/backend/temporal/process_task/tests/test_sandbox_credentials.py
+++ b/products/tasks/backend/temporal/process_task/tests/test_sandbox_credentials.py
@@ -462,3 +462,43 @@ def _task(repo):
         result = _live_sandboxes_for_user_integration(integration.id)
 
         assert result == [(str(live_run.id), "sb-live", "org/live")]
+
+    @pytest.mark.parametrize("marker,included", [("none", True), ("owner", True), ("other", False)])
+    def test_actor_transition_gates_owner_token_propagation(self, marker, included):
+        from posthog.models import Organization, Team
+        from posthog.models.user import User
+        from posthog.models.user_integration import UserIntegration
+
+        from products.tasks.backend.models import Task, TaskRun
+        from products.tasks.backend.temporal.process_task.sandbox_credentials import (
+            _live_sandboxes_for_user_integration,
+        )
+        from products.tasks.backend.temporal.process_task.utils import mark_sandbox_github_identity
+
+        org = Organization.objects.create(name="o")
+        team = Team.objects.create(organization=org, name="t")
+        owner = User.objects.create(email="owner@test.com")
+        other = User.objects.create(email="other@test.com")
+        integration = UserIntegration.objects.create(
+            user=owner, kind=UserIntegration.IntegrationKind.GITHUB, integration_id="i1", config={}, sensitive_config={}
+        )
+        task = Task.objects.create(
+            team=team, created_by=owner, repository="org/repo", github_user_integration=integration
+        )
+        run = TaskRun.objects.create(
+            task=task,
+            team=team,
+            status=TaskRun.Status.IN_PROGRESS,
+            state={"sandbox_id": "sb-x", "pr_authorship_mode": "user"},
+        )
+        # An unset marker (no transition yet) and one bound to the owner both propagate; a marker
+        # bound to a different per-message actor means the sandbox was logged out / rebound, so the
+        # owner's rotating token must not overwrite it.
+        if marker == "owner":
+            mark_sandbox_github_identity("sb-x", owner.id)
+        elif marker == "other":
+            mark_sandbox_github_identity("sb-x", other.id)
+
+        result = _live_sandboxes_for_user_integration(integration.id)
+
+        assert (result == [(str(run.id), "sb-x", "org/repo")]) is included