feat(core): persist v2 session context epochs

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

@@ -32,5 +32,9 @@ export const migrations = (
     import("./migration/20260603141458_session_input_inbox"),
     import("./migration/20260603160727_jittery_ezekiel_stane"),
     import("./migration/20260604172448_event_sourced_session_input"),
+    import("./migration/20260604180746_add_session_context_epoch"),
+    import("./migration/20260604181329_add_session_context_updates"),
+    import("./migration/20260604181706_add_session_context_replacement"),
+    import("./migration/20260604181807_add_session_context_replacement_sequence"),
   ])
 ).map((module) => module.default) satisfies DatabaseMigration.Migration[]

packages/core/src/database/migration/20260604180746_add_session_context_epoch.ts

@@ -0,0 +1,19 @@
+import { Effect } from "effect"
+import type { DatabaseMigration } from "../migration"
+
+export default {
+  id: "20260604180746_add_session_context_epoch",
+  up(tx) {
+    return Effect.gen(function* () {
+      yield* tx.run(`
+        CREATE TABLE \`session_context_epoch\` (
+          \`session_id\` text PRIMARY KEY,
+          \`baseline\` text NOT NULL,
+          \`checkpoint\` text NOT NULL,
+          \`baseline_seq\` integer NOT NULL,
+          CONSTRAINT \`fk_session_context_epoch_session_id_session_id_fk\` FOREIGN KEY (\`session_id\`) REFERENCES \`session\`(\`id\`) ON DELETE CASCADE
+        );
+      `)
+    })
+  },
+} satisfies DatabaseMigration.Migration

packages/core/src/database/migration/20260604181329_add_session_context_updates.ts

@@ -0,0 +1,23 @@
+import { Effect } from "effect"
+import type { DatabaseMigration } from "../migration"
+
+export default {
+  id: "20260604181329_add_session_context_updates",
+  up(tx) {
+    return Effect.gen(function* () {
+      yield* tx.run(`
+        CREATE TABLE \`session_context_message\` (
+          \`session_id\` text NOT NULL,
+          \`seq\` integer NOT NULL,
+          \`parts\` text NOT NULL,
+          CONSTRAINT \`session_context_message_pk\` PRIMARY KEY(\`session_id\`, \`seq\`),
+          CONSTRAINT \`fk_session_context_message_session_id_session_id_fk\` FOREIGN KEY (\`session_id\`) REFERENCES \`session\`(\`id\`) ON DELETE CASCADE
+        );
+      `)
+      yield* tx.run(`ALTER TABLE \`session_context_epoch\` ADD \`revision\` integer DEFAULT 0 NOT NULL;`)
+      yield* tx.run(
+        `CREATE INDEX \`session_context_message_session_seq_idx\` ON \`session_context_message\` (\`session_id\`,\`seq\`);`,
+      )
+    })
+  },
+} satisfies DatabaseMigration.Migration

packages/core/src/database/migration/20260604181706_add_session_context_replacement.ts

@@ -0,0 +1,11 @@
+import { Effect } from "effect"
+import type { DatabaseMigration } from "../migration"
+
+export default {
+  id: "20260604181706_add_session_context_replacement",
+  up(tx) {
+    return Effect.gen(function* () {
+      yield* tx.run(`ALTER TABLE \`session_context_epoch\` ADD \`replacement_pending\` integer DEFAULT false NOT NULL;`)
+    })
+  },
+} satisfies DatabaseMigration.Migration

packages/core/src/database/migration/20260604181807_add_session_context_replacement_sequence.ts

@@ -0,0 +1,11 @@
+import { Effect } from "effect"
+import type { DatabaseMigration } from "../migration"
+
+export default {
+  id: "20260604181807_add_session_context_replacement_sequence",
+  up(tx) {
+    return Effect.gen(function* () {
+      yield* tx.run(`ALTER TABLE \`session_context_epoch\` ADD \`replacement_seq\` integer;`)
+    })
+  },
+} satisfies DatabaseMigration.Migration