diff --git a/.changeset/pg-ce-sessions-bigint-last-activity.md b/.changeset/pg-ce-sessions-bigint-last-activity.md
new file mode 100644
index 0000000000..3c6fdf1aae
--- /dev/null
+++ b/.changeset/pg-ce-sessions-bigint-last-activity.md
@@ -0,0 +1,7 @@
+---
+"@runfusion/fusion": patch
+---
+
+summary: Fix startup failure where the SQLite → PostgreSQL migration aborted on CE session timestamps.
+category: fix
+dev: project.ce_sessions.last_activity_at was `integer` but stores epoch milliseconds, overflowing PG int4 and failing first-boot auto-migration. Now `bigint` in the Drizzle shape and CE plugin schema-hook DDL, with an idempotent `ALTER COLUMN ... TYPE bigint` for datadirs that already materialized the integer column.
diff --git a/packages/core/src/__tests__/postgres/schema-epoch-ms-integer-overflow.test.ts b/packages/core/src/__tests__/postgres/schema-epoch-ms-integer-overflow.test.ts
new file mode 100644
index 0000000000..a934bcdaf6
--- /dev/null
+++ b/packages/core/src/__tests__/postgres/schema-epoch-ms-integer-overflow.test.ts
@@ -0,0 +1,39 @@
+/*
+FNXC:PostgresSchema 2026-07-13-19:40:
+Regression invariant for the SQLite → PostgreSQL first-boot migration failure
+where project.ce_sessions.last_activity_at was declared `integer` but stores
+epoch milliseconds (Date.now() ≈ 1.78e12), overflowing PG integer (max ~2.1e9)
+and aborting startup ("value ... is out of range for type integer").
+
+Invariant across ALL schemas (project/central/archive/plugin): a numeric column
+whose name marks it as a point-in-time value (`*_at`, `*_time`, `*_timestamp`)
+must be bigint, never 32-bit integer. Timestamp columns stored as ISO text are
+fine; durations/counters (`*_ms` intervals, counts) fit integer and are exempt.
+*/
+import { describe, it, expect } from "vitest";
+import { getTableColumns, getTableName } from "drizzle-orm";
+import { PgTable } from "drizzle-orm/pg-core";
+import * as schema from "../../postgres/schema/index.js";
+
+const TIMESTAMP_NAME = /(_at|_time|_timestamp)$/;
+
+function collectTables(mod: Record<string, unknown>): PgTable[] {
+  return Object.values(mod).filter((v): v is PgTable => v instanceof PgTable);
+}
+
+describe("PG schema epoch-ms columns", () => {
+  it("declares every numeric *_at/*_time/*_timestamp column as bigint, not integer", () => {
+    const offenders: string[] = [];
+    for (const mod of [schema.project, schema.central, schema.archive, schema.plugin]) {
+      for (const table of collectTables(mod as Record<string, unknown>)) {
+        for (const column of Object.values(getTableColumns(table))) {
+          if (!TIMESTAMP_NAME.test(column.name)) continue;
+          if (column.getSQLType() === "integer") {
+            offenders.push(`${getTableName(table)}.${column.name}`);
+          }
+        }
+      }
+    }
+    expect(offenders).toEqual([]);
+  });
+});
diff --git a/packages/core/src/postgres/plugin-schema-hook.ts b/packages/core/src/postgres/plugin-schema-hook.ts
index de9c145529..99011dddac 100644
--- a/packages/core/src/postgres/plugin-schema-hook.ts
+++ b/packages/core/src/postgres/plugin-schema-hook.ts
@@ -107,10 +107,16 @@ export const cePluginSchemaInit: PluginSchemaInitHook = {
         artifact_path text,
         error text,
         turn_interval_ms integer NOT NULL DEFAULT 120000,
-        last_activity_at integer NOT NULL,
+        last_activity_at bigint NOT NULL,
         created_at text NOT NULL,
         updated_at text NOT NULL
       );
+      -- FNXC:PostgresSchema 2026-07-13-19:35:
+      -- last_activity_at holds epoch milliseconds (Date.now()), which overflows
+      -- PG integer. Datadirs created before this fix materialized the column as
+      -- integer via the CREATE TABLE IF NOT EXISTS above, so widen it in place.
+      -- Idempotent: ALTER ... TYPE bigint on an already-bigint column is a no-op.
+      ALTER TABLE project.ce_sessions ALTER COLUMN last_activity_at TYPE bigint;
       CREATE INDEX IF NOT EXISTS "idxCeSessionsStatusUpdated"
         ON project.ce_sessions(status, updated_at DESC, id);
       CREATE INDEX IF NOT EXISTS "idxCeSessionsStageCreated"
diff --git a/packages/core/src/postgres/schema/plugin.ts b/packages/core/src/postgres/schema/plugin.ts
index 4da7bf699d..08fbf75bc2 100644
--- a/packages/core/src/postgres/schema/plugin.ts
+++ b/packages/core/src/postgres/schema/plugin.ts
@@ -16,7 +16,7 @@
  * while still materializing on a fresh database.
  */
 
-import { text, integer, boolean, foreignKey, index, uniqueIndex } from "drizzle-orm/pg-core";
+import { text, integer, bigint, boolean, foreignKey, index, uniqueIndex } from "drizzle-orm/pg-core";
 import { projectSchema } from "./project.js";
 
 /**
@@ -87,7 +87,14 @@ export const ceSessions = projectSchema.table("ce_sessions", {
   artifactPath: text("artifact_path"),
   error: text("error"),
   turnIntervalMs: integer("turn_interval_ms").notNull().default(120000),
-  lastActivityAt: integer("last_activity_at").notNull(),
+  /*
+  FNXC:PostgresSchema 2026-07-13-19:35:
+  last_activity_at stores epoch milliseconds (Date.now()), which overflows PG
+  integer (max ~2.1e9) — epoch-ms values are ~1.78e12. Must be bigint like the
+  other epoch-ms columns (see project.ts pr_* tables). An integer column here
+  broke the SQLite → PostgreSQL first-boot auto-migration and blocked startup.
+  */
+  lastActivityAt: bigint("last_activity_at", { mode: "number" }).notNull(),
   createdAt: text("created_at").notNull(),
   updatedAt: text("updated_at").notNull(),
 }, (t) => [