diff --git a/backend/security/src/migrations/015_root_membership_backfill_and_personal_org_reclassify.ts b/backend/security/src/migrations/015_root_membership_backfill_and_personal_org_reclassify.ts
index 014f2537..0e13caa0 100644
--- a/backend/security/src/migrations/015_root_membership_backfill_and_personal_org_reclassify.ts
+++ b/backend/security/src/migrations/015_root_membership_backfill_and_personal_org_reclassify.ts
@@ -11,15 +11,36 @@ import { ROOT_ORG_ID } from './014_seed_root_platform_organization'
  * amendment below — they are NOT independent):
  *
  *  (a) BACKFILL — every user without an existing `organization_memberships`
- *      row in the root org (ROOT_ORG_ID, any role) gets one with
- *      `role='member', status='active'`. A user who already has a row (most
- *      commonly the root org's own owner, seeded by migration 014) is left
- *      untouched — this is a "fill the gap", not a "reset everyone to
- *      member" migration. Runs even if `organizations` has no root row yet
- *      (defers to 0 rows matched, self-heals on a later boot once 014/015 or
- *      the monolith's chain seeds it) — a user whose org can't be resolved
- *      still isn't skipped outright, they simply pick up their root row the
- *      next time this migration (or the provisioning self-heal path) runs.
+ *      row in the root org gets one with `role='member', status='active'`.
+ *      A user who already has a row (most commonly the root org's own owner,
+ *      seeded by migration 014) is left untouched — this is a "fill the gap",
+ *      not a "reset everyone to member" migration. Runs even if
+ *      `organizations` has no root row yet (skips outright, self-heals on a
+ *      later boot once 014/015 or the monolith's chain seeds it) — a user
+ *      whose org can't be resolved still isn't skipped outright, they simply
+ *      pick up their root row the next time this migration (or the
+ *      provisioning self-heal path) runs.
+ *
+ *      ROOT ORG RESOLUTION (2026-08-16 P1 fix): this step does NOT hardcode
+ *      `ROOT_ORG_ID` into the INSERT. It resolves the actual root org row the
+ *      SAME WAY `portalRepository.ensureRootPortal()` does — prefer the row
+ *      whose id is `ROOT_ORG_ID`, else fall back to the oldest
+ *      `organizations` row of `type='platform'`. That fallback is required
+ *      because migration 014's own "adopt a pre-existing platform org rather
+ *      than creating a second one" branch can leave a prod DB with a real
+ *      platform-root org under a DIFFERENT id and NO `ROOT_ORG_ID` row at
+ *      all — exactly what happened on the 2026-07-29 rebuild (the adopted
+ *      org is `92f2020b-2bdb-41f0-98ff-1ef759b41741`, slug `fuzefront`,
+ *      which also means a second platform org can never be created under
+ *      `ROOT_ORG_ID` — that slug is taken). Hardcoding `ROOT_ORG_ID` here
+ *      made every INSERT violate `organization_memberships_organization_id_
+ *      foreign` (23503) on such a DB, which is NOT caught by
+ *      `ON CONFLICT DO NOTHING` (that only dedupes committed conflicts, it
+ *      does not catch a failed insert), and knex propagated the error out of
+ *      `initializeDatabase()` on every boot — the fuzefront-backend /
+ *      fuzefront-security 2026-08-16 P1 crashloop. If NO platform org exists
+ *      at all yet (fresh/schema-only DB), this step is skipped outright and
+ *      self-heals once one exists.
  *
  *  (b) RECLASSIFY — every `organizations` row with `type='personal'` becomes
  *      `type='organization'`. Non-destructive: nothing is deleted, no other
@@ -28,14 +49,16 @@ import { ROOT_ORG_ID } from './014_seed_root_platform_organization'
  *      enum value is kept for back-compat (Postgres cannot drop an enum
  *      value) but is no longer written once the flag is ON.
  *
- * IDEMPOTENT: (a) is an INSERT..SELECT guarded by NOT EXISTS on the unique
- * (user_id, organization_id) pair, PLUS `ON CONFLICT DO NOTHING` as a second
- * belt-and-braces guard against a concurrent insert of the same pair between
- * the SELECT and the INSERT. (b) is a plain UPDATE whose WHERE clause matches
- * zero rows once every personal org has already been reclassified. Both are
- * safe to run any number of times with no diff after the first successful run
- * — verified by `tests/migrations.rootMembershipBackfill.test.ts` (run + re-run
- * on a scratch DB).
+ * IDEMPOTENT: (a) is a root-org lookup (safe to repeat; re-resolves the same
+ * row every run) followed by an INSERT..SELECT guarded by NOT EXISTS on the
+ * unique (user_id, organization_id) pair, PLUS `ON CONFLICT DO NOTHING` as a
+ * second belt-and-braces guard against a concurrent insert of the same pair
+ * between the SELECT and the INSERT. (b) is a plain UPDATE whose WHERE clause
+ * matches zero rows once every personal org has already been reclassified.
+ * Both are safe to run any number of times with no diff after the first
+ * successful run — verified by `tests/migrations.rootMembershipBackfill.test.ts`
+ * (run + re-run on a scratch DB, PLUS a dedicated "ROOT_ORG_ID row absent,
+ * only an adopted platform org exists" regression case for the P1 above).
  *
  * PRECONDITION on BOTH (a) and (b): the `ROOT_ORG_ID` row must exist. It is a
  * hard-coded constant, not a lookup, and migration 014 has two paths that
@@ -68,33 +91,21 @@ import { ROOT_ORG_ID } from './014_seed_root_platform_organization'
  * land in a deploy window (`deploy-window` label, FF-EPIC-17-S2 DoD).
  */
 export async function up(knex: Knex): Promise<void> {
-  // (a) Backfill root membership for every user lacking one.
-  //
-  // PRECONDITION: the root org row must actually exist. `ROOT_ORG_ID` is a
-  // hard-coded constant, not a lookup, and migration 014 has two paths that
-  // legitimately leave the row ABSENT — it adopts a pre-existing platform org
-  // under a different id, and it defers entirely when there is no user yet.
-  // Neither is an error there, but inserting memberships that reference a
-  // missing organization is a foreign-key violation (23503) that aborts the
-  // migration chain and crash-loops the service on boot. Verify, don't assume:
-  // a step that cannot tell "nothing to do" from "the thing I need is missing"
-  // eventually reports success for the wrong reason.
-  const rootOrg = await knex('organizations').where({ id: ROOT_ORG_ID }).first()
-  if (!rootOrg) {
-    const platform = await knex('organizations')
+  // (a) Resolve the ACTUAL root org row (see the P1 note above), then
+  // backfill root membership for every user lacking one against ITS id —
+  // never the bare ROOT_ORG_ID constant, which may have no `organizations`
+  // row at all on a DB that adopted a pre-existing platform org.
+  const rootOrg =
+    (await knex('organizations').where({ id: ROOT_ORG_ID }).first()) ??
+    (await knex('organizations')
       .where({ type: 'platform' })
       .orderBy('created_at', 'asc')
-      .first()
-    console.error(
-      `[015] SKIPPING root-membership backfill: organization ${ROOT_ORG_ID} does ` +
-        'not exist. ' +
-        (platform
-          ? `The platform organization in this database is ${platform.id}, which ` +
-            'migration 014 adopted rather than repointed. Resolve that first — ' +
-            'until then every ROOT_ORG_ID call site misses.'
-          : 'No platform organization exists at all; migration 014 deferred.') +
-      ' Not inserting memberships that would violate' +
-      ' organization_memberships_organization_id_foreign.'
+      .first())
+
+  if (!rootOrg) {
+    console.log(
+      '[015] no platform root organization exists yet — skipping root-membership ' +
+        'backfill (self-heals on a later boot once 014/ensureRootPortal() seeds one)'
     )
   } else {
     const backfillResult = await knex.raw(
@@ -107,10 +118,12 @@ export async function up(knex: Knex): Promise<void> {
          WHERE om.user_id = u.id AND om.organization_id = ?
        )
        ON CONFLICT (user_id, organization_id) DO NOTHING`,
-      [ROOT_ORG_ID, ROOT_ORG_ID]
+      [rootOrg.id, rootOrg.id]
     )
     console.log(
-      `[015] root-membership backfill: inserted ${backfillResult.rowCount ?? 0} row(s)`
+      `[015] root-membership backfill: inserted ${backfillResult.rowCount ?? 0} row(s) ` +
+        `against root org ${rootOrg.id}` +
+        (rootOrg.id === ROOT_ORG_ID ? '' : ' (adopted platform org, not the canonical ROOT_ORG_ID)')
     )
   }
 
diff --git a/backend/security/tests/migrations.rootMembershipBackfill.test.ts b/backend/security/tests/migrations.rootMembershipBackfill.test.ts
index 02723ba5..e0b3420e 100644
--- a/backend/security/tests/migrations.rootMembershipBackfill.test.ts
+++ b/backend/security/tests/migrations.rootMembershipBackfill.test.ts
@@ -287,3 +287,156 @@ describe('migration 015 — root-membership backfill + personal-org reclassify (
     expect(rootOrg).toBeDefined()
   })
 })
+
+/**
+ * 2026-08-16 P1 regression — reproduces the exact prod condition that put
+ * fuzefront-backend/-security into a crashloop: `organizations` has NO row
+ * whose id is the canonical `ROOT_ORG_ID` (`…0010`), because migration 014's
+ * "adopt a pre-existing platform org rather than creating a second one"
+ * branch had already run against a DB whose platform org was created under a
+ * random id (prod: `92f2020b-2bdb-41f0-98ff-1ef759b41741`, slug `fuzefront`).
+ * Pre-fix, migration 015 hardcoded `ROOT_ORG_ID` into the backfill INSERT,
+ * which violated `organization_memberships_organization_id_foreign` (23503)
+ * on exactly this DB shape — uncaught by `ON CONFLICT DO NOTHING` (that only
+ * dedupes committed conflicts, not a failed insert) — and knex propagated the
+ * error out of `initializeDatabase()` on every boot.
+ *
+ * Uses its own scratch DB (not the suite above) so this describe block can
+ * freely omit ROOT_ORG_ID from `organizations` without disturbing the
+ * happy-path tests, which assume it exists.
+ */
+describe('migration 015 — resilient when the canonical ROOT_ORG_ID row is absent (2026-08-16 P1 regression)', () => {
+  let reachable = false
+  let db: any
+  let ROOT_ORG_ID: string
+  let migration015: { up(knex: any): Promise<void>; down(knex: any): Promise<void> }
+  const TEST_DB2 = 'fuzefront_security_root_backfill_missing_root_test'
+
+  beforeAll(async () => {
+    reachable = await pgReachable()
+    if (!reachable) return
+
+    process.env.USE_POSTGRES = 'true'
+    process.env.NODE_ENV = 'production'
+    process.env.DB_HOST = HOST
+    process.env.DB_PORT = String(PORT)
+    process.env.DB_USER = USER
+    process.env.DB_PASSWORD = PASSWORD
+    process.env.DB_NAME = TEST_DB2
+
+    const admin = new Client({ host: HOST, port: PORT, user: USER, password: PASSWORD, database: 'postgres' })
+    await admin.connect()
+    await admin.query(`DROP DATABASE IF EXISTS ${TEST_DB2}`)
+    await admin.query(`CREATE DATABASE ${TEST_DB2}`)
+    await admin.end()
+
+    const core = require('@fuzefront/core')
+    const migDir = path.join(__dirname, '..', 'dist', 'migrations')
+    // Run only the schema chain, NOT 014/015 — this test seeds the
+    // "adopted platform org, ROOT_ORG_ID absent" condition by hand and then
+    // invokes 015's up() directly, mirroring how the real deploy runs it.
+    await core.runMigrations({ migrationsTableName: 'knex_migrations', migrationsDir: migDir })
+    core.initializeDatabaseConnection({ migrationsTableName: 'knex_migrations', migrationsDir: migDir })
+    db = core.db
+
+    const rootOrgMigration = require('../src/migrations/014_seed_root_platform_organization')
+    ROOT_ORG_ID = rootOrgMigration.ROOT_ORG_ID
+    migration015 = require('../src/migrations/015_root_membership_backfill_and_personal_org_reclassify')
+
+    // The full chain above already ran 014/015 on a zero-user DB, so they
+    // deferred (no organizations row at all yet) — confirmed below. Now
+    // simulate the prod condition: a platform org exists under a RANDOM id
+    // (adopted, e.g. by an earlier ensureRootPortal() run), and ROOT_ORG_ID
+    // itself has no row.
+    const preexisting = await db('organizations').where({ id: ROOT_ORG_ID }).first()
+    if (preexisting) {
+      throw new Error('test setup invariant violated: ROOT_ORG_ID row should not exist yet')
+    }
+
+    const adoptedOwnerId = uuidv4()
+    await db('users').insert({
+      id: adoptedOwnerId,
+      email: 'adopted-owner@test.local',
+      first_name: 'Adopted',
+      last_name: 'Owner',
+      roles: JSON.stringify(['admin', 'user']),
+      created_at: new Date(),
+      updated_at: new Date(),
+    })
+    await db('organizations').insert({
+      id: uuidv4(),
+      name: 'FuzeFront',
+      slug: 'fuzefront', // matches prod: this slug is already taken by the adopted org
+      owner_id: adoptedOwnerId,
+      type: 'platform',
+      settings: JSON.stringify({}),
+      metadata: JSON.stringify({ root: true }),
+      is_active: true,
+      provisioning_state: 'active',
+    })
+  }, 60000)
+
+  afterAll(async () => {
+    if (db) await db.destroy()
+  })
+
+  async function createUser(): Promise<string> {
+    const id = uuidv4()
+    await db('users').insert({
+      id,
+      email: `missing-root-${id.slice(0, 8)}@test.local`,
+      first_name: 'MissingRoot',
+      last_name: 'Test',
+      roles: JSON.stringify(['user']),
+      created_at: new Date(),
+      updated_at: new Date(),
+    })
+    return id
+  }
+
+  it('does NOT throw an FK violation, backfills against the ADOPTED org, and creates no second platform org', async () => {
+    if (!reachable) return console.warn('Postgres unreachable — skipping')
+
+    // Precondition matching prod exactly.
+    const canonical = await db('organizations').where({ id: ROOT_ORG_ID }).first()
+    expect(canonical).toBeUndefined()
+    const adopted = await db('organizations').where({ type: 'platform' }).first()
+    expect(adopted).toBeDefined()
+
+    const user = await createUser()
+
+    // Pre-fix this threw a Postgres 23503 FK violation. Post-fix it must
+    // resolve to the adopted org and succeed.
+    await expect(migration015.up(db)).resolves.toBeUndefined()
+
+    const membership = await db('organization_memberships')
+      .where({ user_id: user, organization_id: adopted.id })
+      .first()
+    expect(membership).toMatchObject({ role: 'member', status: 'active' })
+
+    // No row was ever inserted under the (still-nonexistent) canonical id.
+    const canonicalMembership = await db('organization_memberships')
+      .where({ organization_id: ROOT_ORG_ID })
+      .first()
+    expect(canonicalMembership).toBeUndefined()
+
+    // Exactly ONE platform org — the fix must never create a second one.
+    const platformOrgs = await db('organizations').where({ type: 'platform' })
+    expect(platformOrgs).toHaveLength(1)
+    expect(platformOrgs[0].id).toBe(adopted.id)
+  })
+
+  it('is idempotent when re-run against the same adopted-root DB', async () => {
+    if (!reachable) return console.warn('Postgres unreachable — skipping')
+
+    const membershipsBefore = await db('organization_memberships').select('id').orderBy('id')
+    const orgsBefore = await db('organizations').select('id', 'type').orderBy('id')
+
+    await expect(migration015.up(db)).resolves.toBeUndefined()
+
+    const membershipsAfter = await db('organization_memberships').select('id').orderBy('id')
+    const orgsAfter = await db('organizations').select('id', 'type').orderBy('id')
+    expect(membershipsAfter).toEqual(membershipsBefore)
+    expect(orgsAfter).toEqual(orgsBefore)
+  })
+})
diff --git a/backend/src/migrations/022_root_membership_backfill_and_personal_org_reclassify.ts b/backend/src/migrations/022_root_membership_backfill_and_personal_org_reclassify.ts
index a78728d9..7eb43812 100644
--- a/backend/src/migrations/022_root_membership_backfill_and_personal_org_reclassify.ts
+++ b/backend/src/migrations/022_root_membership_backfill_and_personal_org_reclassify.ts
@@ -16,13 +16,33 @@ import { ROOT_ORG_ID } from './015_seed_root_platform_organization'
  * amendment below — they are NOT independent):
  *
  *  (a) BACKFILL — every user without an existing `organization_memberships`
- *      row in the root org (ROOT_ORG_ID, any role) gets one with
- *      `role='member', status='active'`. A user who already has a row (most
- *      commonly the root org's own owner, seeded by migration 015) is left
- *      untouched — this is a "fill the gap", not a "reset everyone to
- *      member" migration. A user whose org can't be resolved still isn't
- *      skipped outright — root membership is universal and never depends on
- *      org resolution.
+ *      row in the root org gets one with `role='member', status='active'`.
+ *      A user who already has a row (most commonly the root org's own owner,
+ *      seeded by migration 015) is left untouched — this is a "fill the gap",
+ *      not a "reset everyone to member" migration. A user whose org can't be
+ *      resolved still isn't skipped outright — root membership is universal
+ *      and never depends on org resolution.
+ *
+ *      ROOT ORG RESOLUTION (2026-08-16 P1 fix): this step does NOT hardcode
+ *      `ROOT_ORG_ID` into the INSERT. It resolves the actual root org row the
+ *      SAME WAY `portalRepository.ensureRootPortal()` does — prefer the row
+ *      whose id is `ROOT_ORG_ID`, else fall back to the oldest
+ *      `organizations` row of `type='platform'`. That fallback is required
+ *      because migration 015's own "adopt a pre-existing platform org rather
+ *      than creating a second one" branch can leave a prod DB with a real
+ *      platform-root org under a DIFFERENT id and NO `ROOT_ORG_ID` row at
+ *      all — exactly what happened on the 2026-07-29 rebuild (the adopted
+ *      org is `92f2020b-2bdb-41f0-98ff-1ef759b41741`, slug `fuzefront`,
+ *      which also means a second platform org can never be created under
+ *      `ROOT_ORG_ID` — that slug is taken). Hardcoding `ROOT_ORG_ID` here
+ *      made every INSERT violate `organization_memberships_organization_id_
+ *      foreign` (23503) on such a DB, which is NOT caught by
+ *      `ON CONFLICT DO NOTHING` (that only dedupes committed conflicts, it
+ *      does not catch a failed insert), and knex propagated the error out of
+ *      `initializeDatabase()` on every boot — the fuzefront-backend /
+ *      fuzefront-security 2026-08-16 P1 crashloop. If NO platform org exists
+ *      at all yet (fresh/schema-only DB), this step is skipped outright and
+ *      self-heals once one exists.
  *
  *  (b) RECLASSIFY — every `organizations` row with `type='personal'` becomes
  *      `type='organization'`. Non-destructive: nothing is deleted, no other
@@ -31,15 +51,18 @@ import { ROOT_ORG_ID } from './015_seed_root_platform_organization'
  *      enum value is kept for back-compat (Postgres cannot drop an enum
  *      value) but is no longer written once the flag is ON.
  *
- * IDEMPOTENT: (a) is an INSERT..SELECT guarded by NOT EXISTS on the unique
- * (user_id, organization_id) pair, PLUS `ON CONFLICT DO NOTHING` as a second
- * belt-and-braces guard against a concurrent insert of the same pair between
- * the SELECT and the INSERT. (b) is a plain UPDATE whose WHERE clause matches
- * zero rows once every personal org has already been reclassified. Both are
- * safe to run any number of times with no diff after the first successful
- * run — verified by `backend/security/tests/
- * migrations.rootMembershipBackfill.test.ts` (run + re-run on a scratch DB);
- * this monolith copy is byte-identical SQL, so the same proof applies.
+ * IDEMPOTENT: (a) is a root-org lookup (safe to repeat; re-resolves the same
+ * row every run) followed by an INSERT..SELECT guarded by NOT EXISTS on the
+ * unique (user_id, organization_id) pair, PLUS `ON CONFLICT DO NOTHING` as a
+ * second belt-and-braces guard against a concurrent insert of the same pair
+ * between the SELECT and the INSERT. (b) is a plain UPDATE whose WHERE clause
+ * matches zero rows once every personal org has already been reclassified.
+ * Both are safe to run any number of times with no diff after the first
+ * successful run — verified by `backend/security/tests/
+ * migrations.rootMembershipBackfill.test.ts` (run + re-run on a scratch DB,
+ * PLUS a dedicated "ROOT_ORG_ID row absent, only an adopted platform org
+ * exists" regression case for the P1 above); this monolith copy is
+ * byte-identical SQL, so the same proof applies.
  *
  * PRECONDITION on BOTH (a) and (b): the `ROOT_ORG_ID` row must exist. It is a
  * hard-coded constant, not a lookup, and migration 015 has two paths that
@@ -72,33 +95,21 @@ import { ROOT_ORG_ID } from './015_seed_root_platform_organization'
  * land in a deploy window (`deploy-window` label, FF-EPIC-17-S2 DoD).
  */
 export async function up(knex: Knex): Promise<void> {
-  // (a) Backfill root membership for every user lacking one.
-  //
-  // PRECONDITION: the root org row must actually exist. `ROOT_ORG_ID` is a
-  // hard-coded constant, not a lookup, and migration 015 has two paths that
-  // legitimately leave the row ABSENT — it adopts a pre-existing platform org
-  // under a different id, and it defers entirely when there is no user yet.
-  // Neither is an error there, but inserting memberships that reference a
-  // missing organization is a foreign-key violation (23503) that aborts the
-  // migration chain and crash-loops the service on boot. Verify, don't assume:
-  // a step that cannot tell "nothing to do" from "the thing I need is missing"
-  // eventually reports success for the wrong reason.
-  const rootOrg = await knex('organizations').where({ id: ROOT_ORG_ID }).first()
-  if (!rootOrg) {
-    const platform = await knex('organizations')
+  // (a) Resolve the ACTUAL root org row (see the P1 note above), then
+  // backfill root membership for every user lacking one against ITS id —
+  // never the bare ROOT_ORG_ID constant, which may have no `organizations`
+  // row at all on a DB that adopted a pre-existing platform org.
+  const rootOrg =
+    (await knex('organizations').where({ id: ROOT_ORG_ID }).first()) ??
+    (await knex('organizations')
       .where({ type: 'platform' })
       .orderBy('created_at', 'asc')
-      .first()
-    console.error(
-      `[022] SKIPPING root-membership backfill: organization ${ROOT_ORG_ID} does ` +
-        'not exist. ' +
-        (platform
-          ? `The platform organization in this database is ${platform.id}, which ` +
-            'migration 015 adopted rather than repointed. Resolve that first — ' +
-            'until then every ROOT_ORG_ID call site misses.'
-          : 'No platform organization exists at all; migration 015 deferred.') +
-      ' Not inserting memberships that would violate' +
-      ' organization_memberships_organization_id_foreign.'
+      .first())
+
+  if (!rootOrg) {
+    console.log(
+      '[022] no platform root organization exists yet — skipping root-membership ' +
+        'backfill (self-heals on a later boot once 015/ensureRootPortal() seeds one)'
     )
   } else {
     const backfillResult = await knex.raw(
@@ -111,10 +122,12 @@ export async function up(knex: Knex): Promise<void> {
          WHERE om.user_id = u.id AND om.organization_id = ?
        )
        ON CONFLICT (user_id, organization_id) DO NOTHING`,
-      [ROOT_ORG_ID, ROOT_ORG_ID]
+      [rootOrg.id, rootOrg.id]
     )
     console.log(
-      `[022] root-membership backfill: inserted ${backfillResult.rowCount ?? 0} row(s)`
+      `[022] root-membership backfill: inserted ${backfillResult.rowCount ?? 0} row(s) ` +
+        `against root org ${rootOrg.id}` +
+        (rootOrg.id === ROOT_ORG_ID ? '' : ' (adopted platform org, not the canonical ROOT_ORG_ID)')
     )
   }