feat(db): move container config from filesystem to DB

Source of truth for container runtime config moves from
groups/<folder>/container.json to a new container_configs table.
The file becomes a materialized view written at spawn time.

- New container_configs table with scalar columns (provider, model,
  effort, image_tag, assistant_name, max_messages_per_prompt) and
  JSON columns (mcp_servers, packages_apt, packages_npm, skills,
  additional_mounts)
- Startup backfill seeds DB from existing container.json files
- materializeContainerJson() replaces readContainerConfig + ensureRuntimeFields
- Self-mod handlers (install_packages, add_mcp_server) write to DB
- Provider cascade simplified: session -> container_configs -> 'claude'
- ncl groups config-{get,update,add-mcp-server,remove-mcp-server,
  add-package,remove-package} custom operations
- restartAgentGroupContainers() helper for config change propagation
- Container side unchanged (still reads /workspace/agent/container.json)

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

src/db/container-configs.ts

@@ -0,0 +1,84 @@
+import type { ContainerConfigRow } from '../types.js';
+import { getDb } from './connection.js';
+
+export function getContainerConfig(agentGroupId: string): ContainerConfigRow | undefined {
+  return getDb().prepare('SELECT * FROM container_configs WHERE agent_group_id = ?').get(agentGroupId) as
+    | ContainerConfigRow
+    | undefined;
+}
+
+export function getAllContainerConfigs(): ContainerConfigRow[] {
+  return getDb().prepare('SELECT * FROM container_configs').all() as ContainerConfigRow[];
+}
+
+/** Insert a new config row. Caller must supply all JSON fields (use defaults for empty). */
+export function createContainerConfig(config: ContainerConfigRow): void {
+  getDb()
+    .prepare(
+      `INSERT INTO container_configs (
+        agent_group_id, provider, model, effort, image_tag, assistant_name,
+        max_messages_per_prompt, skills, mcp_servers, packages_apt, packages_npm,
+        additional_mounts, updated_at
+      ) VALUES (
+        @agent_group_id, @provider, @model, @effort, @image_tag, @assistant_name,
+        @max_messages_per_prompt, @skills, @mcp_servers, @packages_apt, @packages_npm,
+        @additional_mounts, @updated_at
+      )`,
+    )
+    .run(config);
+}
+
+/** Create an empty config row with sensible defaults. Idempotent — no-ops if row exists. */
+export function ensureContainerConfig(agentGroupId: string): void {
+  getDb()
+    .prepare(
+      `INSERT OR IGNORE INTO container_configs (agent_group_id, updated_at)
+       VALUES (?, ?)`,
+    )
+    .run(agentGroupId, new Date().toISOString());
+}
+
+/** Update scalar fields on a config row. Only touches fields present in `updates`. */
+export function updateContainerConfigScalars(
+  agentGroupId: string,
+  updates: Partial<
+    Pick<
+      ContainerConfigRow,
+      'provider' | 'model' | 'effort' | 'image_tag' | 'assistant_name' | 'max_messages_per_prompt'
+    >
+  >,
+): void {
+  const fields: string[] = [];
+  const values: Record<string, unknown> = { agent_group_id: agentGroupId };
+
+  for (const [key, value] of Object.entries(updates)) {
+    if (value !== undefined) {
+      fields.push(`${key} = @${key}`);
+      values[key] = value;
+    }
+  }
+  if (fields.length === 0) return;
+
+  fields.push('updated_at = @updated_at');
+  values.updated_at = new Date().toISOString();
+
+  getDb()
+    .prepare(`UPDATE container_configs SET ${fields.join(', ')} WHERE agent_group_id = @agent_group_id`)
+    .run(values);
+}
+
+/** Overwrite a JSON column wholesale. Used for skills, mcp_servers, packages_*, additional_mounts. */
+export function updateContainerConfigJson(
+  agentGroupId: string,
+  column: 'skills' | 'mcp_servers' | 'packages_apt' | 'packages_npm' | 'additional_mounts',
+  value: unknown,
+): void {
+  const now = new Date().toISOString();
+  getDb()
+    .prepare(`UPDATE container_configs SET ${column} = ?, updated_at = ? WHERE agent_group_id = ?`)
+    .run(JSON.stringify(value), now, agentGroupId);
+}
+
+export function deleteContainerConfig(agentGroupId: string): void {
+  getDb().prepare('DELETE FROM container_configs WHERE agent_group_id = ?').run(agentGroupId);
+}