test(agent): cover pluginized agent runner runtime

src/langbot/pkg/agent/runner/registry.py

@@ -146,8 +146,10 @@ class AgentRunnerRegistry:
         Returns:
             List of runner descriptors
         """
-        if use_cache and self._cache is not None:
-            # Filter from cache
+        if use_cache and self._cache is not None and self._cache:
+            # Filter from cache. Do not treat an empty cache as final because the
+            # plugin runtime may still be launching installed plugins when the
+            # first metadata request arrives.
             return self._filter_runners_by_bound_plugins(self._cache, bound_plugins)
 
         # Discover fresh (always full list)

src/langbot/pkg/persistence/alembic/versions/0006_normalize_mcp_remote_mode.py

@@ -10,7 +10,7 @@ ssereadtimeout) live in ``extra_args`` and are left untouched — the
 auto-detecting remote transport consumes them regardless.
 
 Revision ID: 0006_normalize_mcp_remote_mode
-Revises: 0005_add_llm_context_length
+Revises: 8d3a1f2c4b6e
 Create Date: 2026-06-21
 """
 
@@ -18,7 +18,7 @@ import sqlalchemy as sa
 from alembic import op
 
 revision = '0006_normalize_mcp_remote_mode'
-down_revision = '0005_add_llm_context_length'
+down_revision = '8d3a1f2c4b6e'
 branch_labels = None
 depends_on = None