diff --git a/.changeset/claim-seed-ownership-skip-external.md b/.changeset/claim-seed-ownership-skip-external.md
new file mode 100644
index 0000000000..f5b8dec9f9
--- /dev/null
+++ b/.changeset/claim-seed-ownership-skip-external.md
@@ -0,0 +1,7 @@
+---
+"@objectstack/plugin-security": patch
+---
+
+`claimSeedOwnership` now skips **external (federated) objects** — those with an `external` remote-table binding (ADR-0015) — the same way it already skips `managedBy` and `sys_*` objects.
+
+The seed-ownership backfill walks every registered object that exposes an `owner_id` column and re-owns its unowned rows to the first admin. Federated objects get `owner_id` auto-injected into their schema, so they passed the filter and the backfill issued `select id from <remote_table> where owner_id is null` against a read-only remote datasource whose table may not be provisioned yet at boot — producing startup errors like `Find operation failed … no such table: customers`. External objects are read-only (DDL forbidden, writes double-opt-in) and their ownership is not the platform's to reassign, so they are excluded from the scan entirely.
diff --git a/.changeset/wasm-sqlite-durability.md b/.changeset/wasm-sqlite-durability.md
new file mode 100644
index 0000000000..1b7f3919cd
--- /dev/null
+++ b/.changeset/wasm-sqlite-durability.md
@@ -0,0 +1,9 @@
+---
+"@objectstack/driver-sqlite-wasm": patch
+---
+
+Harden the wasm SQLite driver (the dev fallback used when native `better-sqlite3` has an ABI mismatch) against three failure modes that spammed `pnpm dev`:
+
+- **Atomic flushes.** The database was persisted with a plain `writeFile` that truncates-then-streams in place, so a process killed mid-write (a dev-server restart, Ctrl-C, or crash — likely under `on-write`, where every dispatcher tick flushes) left a torn file that sql.js rejected on the next boot with `database disk image is malformed`. Flushes now write to a sibling temp file, `fsync`, and atomically `rename()` over the target, so a reader always sees a complete image.
+- **Corruption self-heal.** When an on-disk image is already corrupt, the driver now detects it at open (via `PRAGMA quick_check`), quarantines the bad file to `<db>.corrupt-<timestamp>`, and boots on a fresh database — instead of failing every query forever with no path to recovery.
+- **`undefined` bindings.** A raw `undefined` binding made sql.js `throw` a plain string (`Wrong API use : tried to bind a value of an unknown type (undefined).`), which aborted the write and logged as a garbled char-indexed object. `undefined` is now coerced to SQL `NULL`, matching the driver's `useNullAsDefault` semantics and the native better-sqlite3 path.
diff --git a/packages/plugins/driver-sqlite-wasm/src/knex-wasm-dialect.ts b/packages/plugins/driver-sqlite-wasm/src/knex-wasm-dialect.ts
index 1183eb2a84..9fc8b39c8b 100644
--- a/packages/plugins/driver-sqlite-wasm/src/knex-wasm-dialect.ts
+++ b/packages/plugins/driver-sqlite-wasm/src/knex-wasm-dialect.ts
@@ -65,10 +65,20 @@ export interface WasmSqliteConnectionSettings {
 /**
  * Coerce JS values that sql.js cannot bind directly. Mirrors
  * `Client_BetterSQLite3._formatBindings`.
+ *
+ * `undefined` is mapped to `null`: sql.js's binder only accepts
+ * string/number/bigint/boolean/null (and array/blob) and `throw`s a *raw
+ * string* — `"Wrong API use : tried to bind a value of an unknown type
+ * (undefined)."` — for anything else. Because it throws a string rather than
+ * an `Error`, it logs as a garbled char-indexed object and aborts the whole
+ * write. Mapping to `null` matches the `useNullAsDefault` semantics the
+ * dialect is configured with, so a missing/undefined value persists as SQL
+ * `NULL` exactly as it would through better-sqlite3.
  */
 function formatBindings(bindings: unknown[] | undefined): unknown[] {
   if (!bindings) return [];
   return bindings.map((b) => {
+    if (b === undefined) return null;
     if (b instanceof Date) return b.valueOf();
     if (typeof b === 'boolean') return Number(b);
     return b;
diff --git a/packages/plugins/driver-sqlite-wasm/src/sqlite-wasm-driver-durability.test.ts b/packages/plugins/driver-sqlite-wasm/src/sqlite-wasm-driver-durability.test.ts
new file mode 100644
index 0000000000..0643aace84
--- /dev/null
+++ b/packages/plugins/driver-sqlite-wasm/src/sqlite-wasm-driver-durability.test.ts
@@ -0,0 +1,123 @@
+// Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
+
+import { describe, it, expect, afterEach } from 'vitest';
+import {
+  mkdtempSync,
+  rmSync,
+  writeFileSync,
+  readFileSync,
+  readdirSync,
+  existsSync,
+  statSync,
+} from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+
+import { SqliteWasmDriver } from '../src/index.js';
+
+/**
+ * Durability + resilience regressions for the wasm SQLite driver — the dev
+ * fallback used whenever native better-sqlite3 has an ABI mismatch.
+ *
+ *  1. Flushes must be ATOMIC. A non-atomic overwrite torn by a mid-write kill
+ *     left "database disk image is malformed" on the next boot.
+ *  2. An already-corrupt on-disk image must SELF-HEAL: quarantine the bad file
+ *     and boot on a fresh database instead of failing every query forever.
+ *  3. `undefined` bindings must persist as SQL NULL rather than throwing sql.js's
+ *     raw-string "Wrong API use : tried to bind a value of an unknown type".
+ */
+describe('SqliteWasmDriver durability & resilience', () => {
+  const dirs: string[] = [];
+  const drivers: SqliteWasmDriver[] = [];
+
+  function newDir(): string {
+    const dir = mkdtempSync(join(tmpdir(), 'wasm-dur-'));
+    dirs.push(dir);
+    return dir;
+  }
+
+  function track(d: SqliteWasmDriver): SqliteWasmDriver {
+    drivers.push(d);
+    return d;
+  }
+
+  afterEach(async () => {
+    await Promise.all(drivers.splice(0).map((d) => d.disconnect().catch(() => {})));
+    for (const dir of dirs.splice(0)) rmSync(dir, { recursive: true, force: true });
+  });
+
+  it('writes the database file atomically (no leftover temp files)', async () => {
+    const dir = newDir();
+    const file = join(dir, 'atomic.db');
+    const driver = track(new SqliteWasmDriver({ filename: file, persist: 'on-write' }));
+    await driver.initObjects([{ name: 'acct', fields: { name: { type: 'string' } } }]);
+
+    await (driver as any).knex('acct').insert({ id: 'a1', name: 'A' });
+    await (driver as any).flush();
+
+    expect(existsSync(file)).toBe(true);
+    expect(statSync(file).size).toBeGreaterThan(0);
+    // The temp file used for the atomic rename must not survive a clean flush.
+    const leftovers = readdirSync(dir).filter((f) => f.includes('.tmp-'));
+    expect(leftovers).toEqual([]);
+
+    // The written file is a valid, re-readable SQLite image.
+    const reopened = track(
+      new SqliteWasmDriver({ filename: file, persist: 'on-disconnect' }),
+    );
+    const rows = await (reopened as any).knex('acct');
+    expect(rows.length).toBe(1);
+    expect(rows[0].name).toBe('A');
+  });
+
+  it('self-heals a corrupt database image by quarantining it and booting fresh', async () => {
+    const dir = newDir();
+    const file = join(dir, 'corrupt.db');
+    // A file that starts with the SQLite magic header but is otherwise garbage:
+    // sql.js opens it, then blows up on the first page read ("malformed").
+    const junk = Buffer.concat([
+      Buffer.from('SQLite format 3\0', 'binary'),
+      Buffer.alloc(4096, 0xab),
+    ]);
+    writeFileSync(file, junk);
+
+    const warnings: string[] = [];
+    const driver = track(
+      new SqliteWasmDriver({
+        filename: file,
+        persist: 'on-write',
+        logger: { warn: (m: string) => warnings.push(m) },
+      }),
+    );
+
+    // Boot must succeed and queries must work on the fresh database.
+    await driver.initObjects([{ name: 'acct', fields: { name: { type: 'string' } } }]);
+    await (driver as any).knex('acct').insert({ id: 'a1', name: 'healed' });
+    const rows = await (driver as any).knex('acct');
+    expect(rows.length).toBe(1);
+
+    // The corrupt bytes were preserved in a sibling quarantine file, and a
+    // warning was surfaced.
+    const quarantined = readdirSync(dir).filter((f) => f.includes('.corrupt-'));
+    expect(quarantined.length).toBe(1);
+    expect(readFileSync(join(dir, quarantined[0]))).toEqual(junk);
+    expect(warnings.some((w) => w.includes('corrupt'))).toBe(true);
+  });
+
+  it('persists an undefined binding as SQL NULL instead of throwing', async () => {
+    const driver = track(new SqliteWasmDriver({ filename: ':memory:' }));
+    await driver.initObjects([
+      { name: 'acct', fields: { name: { type: 'string' }, note: { type: 'string' } } },
+    ]);
+    const knex = (driver as any).knex;
+
+    // A raw binding of `undefined` is exactly what tripped sql.js's binder.
+    await expect(
+      knex('acct').insert({ id: 'a1', name: 'A', note: undefined }),
+    ).resolves.not.toThrow();
+
+    const rows = await knex('acct').where('id', 'a1');
+    expect(rows.length).toBe(1);
+    expect(rows[0].note).toBeNull();
+  });
+});
diff --git a/packages/plugins/driver-sqlite-wasm/src/wasm-connection.ts b/packages/plugins/driver-sqlite-wasm/src/wasm-connection.ts
index 384fa99872..826395381c 100644
--- a/packages/plugins/driver-sqlite-wasm/src/wasm-connection.ts
+++ b/packages/plugins/driver-sqlite-wasm/src/wasm-connection.ts
@@ -97,6 +97,13 @@ async function loadSqlJs(
  * configurable persistence strategy so the on-disk file stays in sync.
  */
 export class WasmSqliteConnection {
+  /**
+   * Process-wide counter making each atomic-write temp filename unique, so
+   * concurrent connections (or overlapping flushes) never target the same
+   * temp path. Combined with `process.pid` for cross-process uniqueness.
+   */
+  private static tmpSeq = 0;
+
   readonly filename: string;
   readonly persist: PersistMode;
   readonly isEphemeral: boolean;
@@ -177,7 +184,71 @@ export class WasmSqliteConnection {
       if (e?.code !== 'ENOENT') throw e;
     }
 
-    this.db = bytes ? new SQL.Database(bytes) : new SQL.Database();
+    if (!bytes) {
+      this.db = new SQL.Database();
+      return;
+    }
+
+    // Open the on-disk bytes, but guard against a corrupt image. A torn write
+    // (process killed mid-flush before atomic writes existed) or otherwise
+    // damaged file makes `new SQL.Database(bytes)` either throw ("file is not a
+    // database") or open a handle whose every query fails with "database disk
+    // image is malformed" — which, for a background dispatcher on a tick loop,
+    // means the same error spammed forever with no path to recovery. Detect it
+    // once at open, quarantine the bad file, and start fresh so the dev server
+    // becomes usable again instead of wedging.
+    try {
+      const candidate = new SQL.Database(bytes);
+      this.assertReadable(candidate);
+      this.db = candidate;
+    } catch (err) {
+      await this.quarantineCorruptFile(err);
+      this.db = new SQL.Database();
+    }
+  }
+
+  /**
+   * Force sql.js to actually read a page so a malformed image surfaces now
+   * rather than on the first business query. `PRAGMA quick_check` walks the
+   * b-tree structure without the full-scan cost of `integrity_check`; a healthy
+   * database returns a single `ok` row. Any thrown error (raw string or Error)
+   * or a non-`ok` result is treated as corruption.
+   */
+  private assertReadable(db: Database): void {
+    const res = db.exec('PRAGMA quick_check(1)');
+    const first = res?.[0]?.values?.[0]?.[0];
+    if (typeof first === 'string' && first.toLowerCase() !== 'ok') {
+      throw new Error(`sqlite quick_check failed: ${first}`);
+    }
+  }
+
+  /**
+   * Move a corrupt database file aside so its bytes are preserved for
+   * post-mortem while a fresh, empty database takes its place. Best-effort:
+   * failures here must not prevent the server from booting on a clean DB.
+   */
+  private async quarantineCorruptFile(cause: unknown): Promise<void> {
+    if (!this.fs) return;
+    const reason =
+      typeof cause === 'string' ? cause : (cause as Error)?.message ?? String(cause);
+    const backup = `${this.filename}.corrupt-${Date.now()}`;
+    try {
+      await this.fs.rename(this.filename, backup);
+      this.logger.warn(
+        `[driver-sqlite-wasm] Database image at ${this.filename} is corrupt ` +
+          `(${reason}). Quarantined to ${backup} and starting from an empty ` +
+          `database so the server can boot.`,
+      );
+    } catch (renameErr) {
+      // Could not move it aside (e.g. permissions) — overwrite is still better
+      // than looping forever on a malformed image. Warn loudly and continue.
+      this.logger.warn(
+        `[driver-sqlite-wasm] Database image at ${this.filename} is corrupt ` +
+          `(${reason}) and could not be quarantined (${String(renameErr)}). ` +
+          `Starting from an empty database; the corrupt file will be overwritten ` +
+          `on the next flush.`,
+      );
+    }
   }
 
   /**
@@ -271,8 +342,8 @@ export class WasmSqliteConnection {
       try {
         const exported = this.db.export();
         // sql.js returns a Uint8Array; Buffer.from on it shares memory but
-        // works fine for the synchronous writeFile enqueue below.
-        await this.fs!.writeFile(this.filename, Buffer.from(exported));
+        // works fine for the atomic write below.
+        await this.atomicWriteFile(Buffer.from(exported));
       } catch (err) {
         this.dirty = true; // let a later flush retry
         throw err;
@@ -284,6 +355,50 @@ export class WasmSqliteConnection {
     await step;
   }
 
+  /**
+   * Write the database bytes to disk atomically: write to a sibling temp file,
+   * fsync it, then `rename()` it over the target.
+   *
+   * A plain `writeFile(this.filename, …)` truncates the target and streams the
+   * new bytes in place, so a process killed mid-write (a dev-server restart,
+   * Ctrl-C, or crash — likely under `on-write`, where every dispatcher tick
+   * flushes) leaves a half-written file. sql.js then rejects that file on the
+   * next boot with "database disk image is malformed". `rename(2)` is atomic
+   * within a filesystem, so a reader always sees either the complete old file
+   * or the complete new one — never a torn image. The temp file lives in the
+   * same directory as the target so the rename stays intra-filesystem.
+   */
+  private async atomicWriteFile(data: Buffer): Promise<void> {
+    if (!this.fs) return;
+    const tmp = `${this.filename}.tmp-${process.pid}-${(WasmSqliteConnection.tmpSeq += 1)}`;
+    let handle: import('node:fs/promises').FileHandle | undefined;
+    try {
+      handle = await this.fs.open(tmp, 'w');
+      await handle.writeFile(data);
+      // Flush the bytes to the platter before the rename so a crash can't leave
+      // a renamed-but-empty file behind on filesystems that reorder the two.
+      await handle.sync();
+      await handle.close();
+      handle = undefined;
+      await this.fs.rename(tmp, this.filename);
+    } catch (err) {
+      if (handle) {
+        try {
+          await handle.close();
+        } catch {
+          /* ignore */
+        }
+      }
+      // Clean up the temp file so a failed flush doesn't litter the data dir.
+      try {
+        await this.fs.unlink(tmp);
+      } catch {
+        /* ignore */
+      }
+      throw err;
+    }
+  }
+
   /** Close the database, flushing any pending writes first. */
   async close(): Promise<void> {
     if (this.destroyed) return;
diff --git a/packages/plugins/plugin-security/src/claim-seed-ownership.test.ts b/packages/plugins/plugin-security/src/claim-seed-ownership.test.ts
index a7c08492aa..2fbc8fcc8d 100644
--- a/packages/plugins/plugin-security/src/claim-seed-ownership.test.ts
+++ b/packages/plugins/plugin-security/src/claim-seed-ownership.test.ts
@@ -55,6 +55,25 @@ describe('claimSeedOwnership', () => {
     expect(updates).toHaveLength(0);
   });
 
+  it('skips external (federated) objects even when they expose owner_id', async () => {
+    // Federated read-only objects (ADR-0015) bind to a remote table; the
+    // platform must not scan or re-own them — and the remote table may not even
+    // exist at boot, so a scan would error with "no such table".
+    const schemas = [
+      {
+        name: 'showcase_ext_customer',
+        external: { remoteName: 'customers' },
+        fields: [{ name: 'owner_id' }],
+      },
+    ];
+    const { ql, updates } = makeQL(schemas, {
+      showcase_ext_customer: [{ id: 'c1', owner_id: null }],
+    });
+    expect(await claimSeedOwnership(ql, ADMIN)).toEqual([]);
+    expect(ql.find).not.toHaveBeenCalled();
+    expect(updates).toHaveLength(0);
+  });
+
   it('skips objects without an owner_id field', async () => {
     const schemas = [{ name: 'crm_pricebook', fields: [{ name: 'name' }] }];
     const { ql, updates } = makeQL(schemas, { crm_pricebook: [{ id: 'p1' }] });
diff --git a/packages/plugins/plugin-security/src/claim-seed-ownership.ts b/packages/plugins/plugin-security/src/claim-seed-ownership.ts
index 845efc1bc5..2ceff135b3 100644
--- a/packages/plugins/plugin-security/src/claim-seed-ownership.ts
+++ b/packages/plugins/plugin-security/src/claim-seed-ownership.ts
@@ -54,7 +54,9 @@ function hasOwnerField(schema: ServiceObject): boolean {
  * Walks `ql.registry.getAllObjects()`, filters to schemas that
  *   (a) are not `managedBy` (skip sys_/auth/platform tables),
  *   (b) are not `sys_*`-namespaced,
- *   (c) declare an `owner_id` field,
+ *   (c) are not `external` (federated remote-table bindings — read-only, DDL
+ *       forbidden, and their `owner_id` is not ours to reassign),
+ *   (d) declare an `owner_id` field,
  * and updates the unowned rows as `isSystem`. Returns a per-object summary.
  */
 export async function claimSeedOwnership(
@@ -80,6 +82,13 @@ export async function claimSeedOwnership(
     if (!schema?.name) continue;
     if ((schema as any).managedBy) continue;
     if (schema.name.startsWith('sys_')) continue;
+    // External (federated) objects bind to a remote table on another datasource
+    // (ADR-0015): reads are remapped, DDL is forbidden, and writes need a double
+    // opt-in. Their `owner_id` — if the remote even has the column — is not the
+    // platform's to reassign, and the remote table may not be provisioned when
+    // this runs at boot (e.g. a fixture that seeds later), so a scan errors with
+    // "no such table". Skip them entirely.
+    if ((schema as any).external) continue;
     if (!hasOwnerField(schema)) continue;
 
     try {