feat(core): admit v2 skill guidance (#30843)

packages/core/src/database/migration.gen.ts

@@ -33,5 +33,6 @@ export const migrations = (
     import("./migration/20260603160727_jittery_ezekiel_stane"),
     import("./migration/20260604172448_event_sourced_session_input"),
     import("./migration/20260605003541_add_session_context_snapshot"),
+    import("./migration/20260605042240_add_context_epoch_agent"),
   ])
 ).map((module) => module.default) satisfies DatabaseMigration.Migration[]

packages/core/src/database/migration/20260605042240_add_context_epoch_agent.ts

@@ -0,0 +1,11 @@
+import { Effect } from "effect"
+import type { DatabaseMigration } from "../migration"
+
+export default {
+  id: "20260605042240_add_context_epoch_agent",
+  up(tx) {
+    return Effect.gen(function* () {
+      yield* tx.run(`ALTER TABLE \`session_context_epoch\` ADD \`agent\` text DEFAULT 'build' NOT NULL;`)
+    })
+  },
+} satisfies DatabaseMigration.Migration