perf(agent-runner): improve session registry and orchestrator efficiency

- Add pre-computed _authorized_ids (frozenset) at session registration for O(1) lookup
- Refactor is_resource_allowed() from linear search to set membership check
- Add thread-safe locking to get_session_registry() singleton
- Cache _session_registry and _state_store references in orchestrator __init__
- Add asyncio.gather() for parallel resource building in AgentResourceBuilder
- Create shared test fixtures in tests/unit_tests/agent/conftest.py
- Update test files to import from shared conftest.py

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/langbot/pkg/persistence/alembic/versions/0004_migrate_runner_config.py

@@ -0,0 +1,124 @@
+"""Migrate pipeline config to new runner format
+
+Revision ID: 0004_migrate_runner_config
+Revises: 0003_add_rerank_models
+Create Date: 2026-05-10
+"""
+
+import json
+import sqlalchemy as sa
+from alembic import op
+
+revision = '0004_migrate_runner_config'
+down_revision = '0003_add_rerank_models'
+branch_labels = None
+depends_on = None
+
+# Mapping from old built-in runner names to official plugin runner IDs
+OLD_RUNNER_TO_PLUGIN_RUNNER_ID = {
+    'local-agent': 'plugin:langbot/local-agent/default',
+    'dify-service-api': 'plugin:langbot/dify-agent/default',
+    'n8n-service-api': 'plugin:langbot/n8n-agent/default',
+    'coze-api': 'plugin:langbot/coze-agent/default',
+    'dashscope-app-api': 'plugin:langbot/dashscope-agent/default',
+    'langflow-api': 'plugin:langbot/langflow-agent/default',
+    'tbox-app-api': 'plugin:langbot/tbox-agent/default',
+}
+
+
+def is_plugin_runner_id(runner_id: str) -> bool:
+    """Check if runner ID is in plugin:* format."""
+    return runner_id.startswith('plugin:')
+
+
+def migrate_pipeline_config(config: dict) -> dict:
+    """Migrate pipeline config to new format."""
+    new_config = dict(config)
+    ai_config = new_config.get('ai', {})
+    if not ai_config:
+        return new_config
+
+    runner_config = ai_config.get('runner', {})
+    runner_configs = ai_config.get('runner_config', {})
+
+    # Check for new format first
+    runner_id = runner_config.get('id')
+    if runner_id and is_plugin_runner_id(runner_id):
+        # Already in new format, no need to migrate
+        return new_config
+
+    # Check for old format
+    old_runner_name = runner_config.get('runner')
+    if old_runner_name:
+        # Map to new runner ID
+        if is_plugin_runner_id(old_runner_name):
+            runner_id = old_runner_name
+        else:
+            runner_id = OLD_RUNNER_TO_PLUGIN_RUNNER_ID.get(old_runner_name, old_runner_name)
+
+        # Set new format
+        runner_config['id'] = runner_id
+
+        # Remove old runner field if it's a mapped built-in runner
+        if old_runner_name in OLD_RUNNER_TO_PLUGIN_RUNNER_ID:
+            del runner_config['runner']
+
+        # Migrate runner-specific config and remove old config blocks
+        if old_runner_name in ai_config:
+            old_runner_config = ai_config[old_runner_name]
+            if old_runner_config:
+                runner_configs[runner_id] = old_runner_config
+            # Remove old config block after migration
+            del ai_config[old_runner_name]
+
+        # Also check if runner_id has config under other old name formats
+        for old_name, mapped_id in OLD_RUNNER_TO_PLUGIN_RUNNER_ID.items():
+            if mapped_id == runner_id and old_name in ai_config:
+                runner_configs[runner_id] = ai_config[old_name]
+                # Remove old config block after migration
+                del ai_config[old_name]
+
+    # Update configs
+    ai_config['runner'] = runner_config
+    ai_config['runner_config'] = runner_configs
+    new_config['ai'] = ai_config
+
+    return new_config
+
+
+def upgrade() -> None:
+    """Migrate existing pipeline configs to new runner format."""
+    conn = op.get_bind()
+    inspector = sa.inspect(conn)
+
+    # Check if pipelines table exists (may not exist in fresh install)
+    if 'pipelines' not in inspector.get_table_names():
+        return
+
+    # Get all pipelines
+    result = conn.execute(sa.text('SELECT uuid, config FROM pipelines'))
+    pipelines = result.fetchall()
+
+    for pipeline_uuid, config_json in pipelines:
+        if not config_json:
+            continue
+
+        try:
+            config = json.loads(config_json)
+            migrated_config = migrate_pipeline_config(config)
+
+            # Only update if config changed
+            if json.dumps(config, sort_keys=True) != json.dumps(migrated_config, sort_keys=True):
+                conn.execute(
+                    sa.text('UPDATE pipelines SET config = :config WHERE uuid = :uuid'),
+                    {'config': json.dumps(migrated_config), 'uuid': pipeline_uuid}
+                )
+        except Exception:
+            # Skip invalid configs
+            continue
+
+
+def downgrade() -> None:
+    """Downgrade is not supported for data migration."""
+    # No downgrade - keep configs in new format
+    pass