feat(v2): builder-agent self-modification WIP + container-config as per-group file

Checkpoints the builder-agent dev-agent/worktree/swap flow (create_dev_agent,
request_swap, classifier, deadman, promote) before pivoting to a unified
draft-activate approach with OS-level RO enforcement. Lifts container_config
out of the agent_groups row into groups/<folder>/container.json so install_packages,
add_mcp_server, and rebuild flows can eventually route through the same draft
path as source edits.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/types.ts

@@ -5,7 +5,6 @@ export interface AgentGroup {
   name: string;
   folder: string;
   agent_provider: string | null;
-  container_config: string | null; // JSON: { additionalMounts, timeout }
   created_at: string;
 }
 
@@ -180,6 +179,47 @@ export interface PendingCredential {
   created_at: string;
 }
 
+// ── Pending swaps (central DB, builder-agent feature) ──
+
+/** Classification of a swap's diff — drives approval routing + warning UX. */
+export type SwapClassification = 'group' | 'host' | 'combined';
+
+/**
+ * Swap lifecycle status. Transitions:
+ *   pending_approval → awaiting_confirmation → (finalized | rolled_back | rejected)
+ * `rejected` is also reachable directly from pending_approval.
+ */
+export type SwapStatus =
+  | 'pending_approval'
+  | 'awaiting_confirmation'
+  | 'finalized'
+  | 'rolled_back'
+  | 'rejected';
+
+/**
+ * Deadman handshake state — only meaningful while status = awaiting_confirmation.
+ *   pending_restart  — swap applied, container/host restarting, message 1 not yet sent.
+ *   message1_sent    — handshake prompt delivered, waiting for user confirm/rollback.
+ */
+export type SwapHandshakeState = 'pending_restart' | 'message1_sent';
+
+export interface PendingSwap {
+  request_id: string;
+  dev_agent_id: string;
+  originating_group_id: string;
+  dev_branch: string;
+  commit_sha: string;
+  classification: SwapClassification;
+  status: SwapStatus;
+  summary_json: string;
+  pre_swap_sha: string | null;
+  db_snapshot_path: string | null;
+  deadman_started_at: string | null;
+  deadman_expires_at: string | null;
+  handshake_state: SwapHandshakeState | null;
+  created_at: string;
+}
+
 // ── Agent destinations (central DB) ──
 
 export interface AgentDestination {