@@ -0,0 +1,21 @@
+---
+'@objectstack/platform-objects': patch
+'@objectstack/spec': patch
+'@objectstack/cli': patch
+---
+
+feat(platform-objects): `sys_exchange_rate` — an organization's dated exchange rates, with a Setup list under Localization
+
+Clause-②: no
+Metadata-protocol: none
+
+A new system object holds the rates multi-currency amounts are converted with, one row per currency and effective date:
+
+- **Columns.** `currency` (an ISO 4217 code, checked on write), `rate` (exact decimal, 12 decimal places and 24 digits in all, strictly positive), `effective_date` (date) and `source` (`manual` / `import` / `app`, default `manual`).
+- **Direction.** One row means 1 unit of the organization's home currency (Localization → Default currency) = `rate` units of the row's currency, so a home amount is the foreign amount divided by `rate`. The sentence is exported as `EXCHANGE_RATE_DIRECTION` and shown on the Setup list page; the scale and precision are exported as `EXCHANGE_RATE_SCALE` and `EXCHANGE_RATE_PRECISION`.
+- **One rate per currency per day.** `(currency, effective_date)` is unique within an organization; two organizations may each hold their own EUR rate for the same day.
+- **Who.** Per organization (its `organization_id` is injected and the tenant wall scopes it). Organization administrators read and write it; rank-and-file members do not see it. Every change is captured in the audit log and shown on the record's History tab.
+- **Where.** Setup → Configuration → Exchange Rates, directly under Localization. `PlatformObjectsPlugin` registers the object with the other platform-infrastructure objects. `PLATFORM_OBJECTS_BY_PACKAGE` (`@objectstack/spec`) lists it under `platform-objects`, so a reference to `sys_exchange_rate` resolves as a real platform object.
+- **Upgrade ceremony.** The organization-ownership inventory (`@objectstack/cli`) lists `sys_exchange_rate`, so `os migrate organization-ownership` plans it instead of refusing it as an uninventoried platform table.
+
+Nothing reads the table yet: the write-time home-currency conversion that uses it ships in the same release.
@@ -813,11 +813,17 @@ The Setup app's anchors:
 | `group_people_org` | Users, organizations, business units, teams, invitations |
 | `group_access_control` | Positions, permission sets, sharing rules, API keys |
 | `group_approvals` | Approvals inbox, requests, history, delegations |
-| `group_configuration` | Settings, localization, authentication, email, storage, AI, feature flags, branding |
+| `group_configuration` | Settings, localization, exchange rates, authentication, email, storage, AI, feature flags, branding |
 | `group_diagnostics` | Sessions, notification events, audit log |
 | `group_integrations` | Webhooks, cloud connection |
 | `group_advanced` | OAuth applications |
 
+**Exchange Rates** (`sys_exchange_rate`, under Localization) holds an organization's dated rates, editable by
+its administrators. One row means 1 unit of the home currency (Localization → Default currency) = `rate` units
+of the row's currency, from its effective date until a later row for that currency. To record a month's rates,
+add one row per currency with the first day of the month as the effective date; a correction is an edit to that
+row, and every change lands in the audit log.
+
 Setup is for platform administration and needs `setup.access`. For
 project-specific administration pages, declare an app of your own.
 
 
@@ -781,6 +781,9 @@ export const ORGANIZATION_OWNERSHIP_INVENTORY: readonly InventoryEntry[] = [
   { object: 'sys_queue', census: PMAIN, fate: 'attribution', citation: `${CENSUS_MAIN} (in reach, added since the first census); ${D10_SINGLE}`, anchors: [] },
   { object: 'sys_queue_member', census: PMAIN, fate: 'attribution', citation: `${CENSUS_MAIN} (in reach); names its queue by name, not by id; ${D10_SINGLE}`, anchors: [] },
   { object: 'sys_assignment_cursor', census: PMAIN, fate: 'attribution', citation: `${CENSUS_MAIN} (in reach); names its rule by name, not by id; ${D10_SINGLE}`, anchors: [] },
+  // Exchange rates (`@objectstack/platform-objects`, #27185): an organization's
+  // administrators author its own rate table; no parent row anchors a rate.
+  { object: 'sys_exchange_rate', census: PMAIN, fate: 'attribution', citation: `${CENSUS_MAIN} (in reach, added since the first census); ${D10_SINGLE}`, anchors: [] },
   { object: 'sys_import_job', census: P1, fate: 'attribution', citation: `${D3_ORG_ROWS}; ${D10_SINGLE}`, anchors: [] },
   { object: 'sys_user_preference', census: P1, fate: 'attribution', citation: `${D3_ORG_ROWS}; ${D10_SINGLE}`, anchors: [] },
 
 
@@ -254,14 +254,14 @@ describe('#17647 — Connect-an-Agent visibility: BOTH halves, over the wire', (
             .toContain('nav_connect_agent');
         // The Setup tree the platform admin is served BY THIS COMPOSITION: 9
         // authored groups less `group_approvals`, which nothing contributes
-        // into and the filter collapses, plus the 22 entries
+        // into and the filter collapses, plus the 23 entries
         // `SETUP_NAV_CONTRIBUTIONS` carries, plus the MCP one.
         // `nav_settings_branding` is not among them, and not because of a
         // tenancy wall (this harness boots none): since #24766 it is
         // contributed by `@objectstack/service-settings` together with the
         // `branding` namespace, offered only where no organization wall stands,
         // and this harness composes platform-objects and the MCP bundle alone.
-        expect(allowedIds).toHaveLength(31);
+        expect(allowedIds).toHaveLength(32);
         expect(allowedIds).not.toContain('nav_settings_branding');
         // The two per-user stores are reached from the User record page, not
         // from Setup's menu (#23803).
@@ -284,8 +284,8 @@ describe('#17647 — Connect-an-Agent visibility: BOTH halves, over the wire', (
         expect(withAccountHalf.statusCode).toBe(200);
         expect(withoutAccountHalf.statusCode).toBe(200);
         expect(navIds(withAccountHalf.body?.item)).toEqual(navIds(withoutAccountHalf.body?.item));
-        // 31: the composition the count in the test above states.
-        expect(navIds(withAccountHalf.body?.item)).toHaveLength(31);
+        // 32: the composition the count in the test above states.
+        expect(navIds(withAccountHalf.body?.item)).toHaveLength(32);
 
         // The mechanism behind the invariance, asserted rather than assumed:
         // the bundle aims exactly one contribution at `setup` and one at
 
@@ -187,7 +187,7 @@ import {
 } from '../src/metadata/index.js';
 
 // ── System ────────────────────────────────────────────────────────────────
-import { SysSetting, SysSecret, SysSettingAudit, SysMigration } from '../src/system/index.js';
+import { SysSetting, SysSecret, SysSettingAudit, SysMigration, SysExchangeRate } from '../src/system/index.js';
 
 // ── Existing Setup app + dashboards + translations ────────────────────────
 import { SETUP_APP } from '../src/apps/setup.app.js';
@@ -317,6 +317,7 @@ const config: ObjectStackDefinition = defineStack({
     SysSecret,
     SysSettingAudit,
     SysMigration,
+    SysExchangeRate,
   ] as any,
 
   apps: [SETUP_APP, STUDIO_APP, ACCOUNT_APP] as any,
 
@@ -126,6 +126,12 @@ export const SETUP_NAV_CONTRIBUTIONS: NavigationContribution[] = [
       // both directly. No `requiredPermissions` — matches Branding (read perm is
       // the app's base `setup.access`).
       { id: 'nav_settings_localization', type: 'url', label: 'Localization', url: '/apps/setup/system/settings/localization', icon: 'globe' },
+      // Multi-currency M1-1 (epic #8345): the dated rates from the home
+      // currency Localization sets, so the entry sits directly under it. The
+      // list page states the rate direction (`EXCHANGE_RATE_DIRECTION`). No
+      // `requiredPermissions`: the object grant decides who reads and writes
+      // (organization admins), and Setup itself already needs `setup.access`.
+      { id: 'nav_exchange_rates', type: 'object', label: 'Exchange Rates', objectName: 'sys_exchange_rate', viewName: 'all_rates', icon: 'arrow-right-left' },
       { id: 'nav_settings_company', type: 'url', label: 'Company', url: '/apps/setup/system/settings/company', icon: 'building-2' },
       // `nav_settings_branding` is contributed by `@objectstack/service-settings`
       // with the `branding` namespace, which is offered only where no
 
@@ -38,7 +38,7 @@ const OWNED_OBJECTS = new Set([
   // metadata (sys_view_definition retired as inert, ADR-0131 D13)
   'sys_metadata', 'sys_metadata_history', 'sys_metadata_audit',
   // system
-  'sys_setting', 'sys_secret', 'sys_setting_audit', 'sys_migration',
+  'sys_setting', 'sys_secret', 'sys_setting_audit', 'sys_migration', 'sys_exchange_rate',
 ]);
 
 describe('objects translation bundle ownership (ADR-0029 D8)', () => {
 
@@ -3530,5 +3530,46 @@ export const enObjects: NonNullable<TranslationData['objects']> = {
         label: "Updated At"
       }
     }
+  },
+  sys_exchange_rate: {
+    label: "Exchange Rate",
+    pluralLabel: "Exchange Rates",
+    description: "Exchange rates from the organization's home currency to a foreign currency, by effective date — the rates foreign-currency amounts are converted to the home currency with.",
+    fields: {
+      id: {
+        label: "ID"
+      },
+      currency: {
+        label: "Currency",
+        help: "ISO 4217 code of the foreign currency, uppercase (EUR, JPY, CHF)."
+      },
+      rate: {
+        label: "Rate",
+        help: "1 unit of the organization's home currency (Localization → Default currency) = Rate units of this currency. Example: home currency USD, currency EUR, rate 0.92 means 1 USD = 0.92 EUR."
+      },
+      effective_date: {
+        label: "Effective Date",
+        help: "First date this rate applies to. It stays in force until a later row for the same currency takes over."
+      },
+      source: {
+        label: "Source",
+        help: "How the row arrived: typed in Setup (manual), loaded from a file (import), or written by an app flow (app).",
+        options: {
+          manual: "Manual",
+          import: "Import",
+          app: "App"
+        }
+      }
+    },
+    _views: {
+      all_rates: {
+        label: "All",
+        description: "1 unit of the organization's home currency (Localization → Default currency) = Rate units of this currency. Example: home currency USD, currency EUR, rate 0.92 means 1 USD = 0.92 EUR.",
+        emptyState: {
+          title: "No exchange rates yet",
+          message: "Add one row per currency for each date its rate changes, for example one row per currency at the start of each month."
+        }
+      }
+    }
   }
 };
@@ -124,6 +124,7 @@ export const en: TranslationData = {
         // Configuration
         nav_settings_hub: { label: 'All Settings' },
         nav_settings_localization: { label: 'Localization' },
+        nav_exchange_rates: { label: 'Exchange Rates' },
         nav_settings_company: { label: 'Company' },
         nav_settings_mail: { label: 'Email' },
         nav_settings_branding: { label: 'Branding' },
 
@@ -3530,5 +3530,46 @@ export const esESObjects: NonNullable<TranslationData['objects']> = {
         label: "Actualizado el"
       }
     }
+  },
+  sys_exchange_rate: {
+    label: "Tipo de cambio",
+    pluralLabel: "Tipos de cambio",
+    description: "Tipos de cambio de la moneda local de la organización a una moneda extranjera, por fecha de entrada en vigor: los tipos con los que los importes en moneda extranjera se convierten a la moneda local.",
+    fields: {
+      id: {
+        label: "ID"
+      },
+      currency: {
+        label: "Moneda",
+        help: "Código ISO 4217 de la moneda extranjera, en mayúsculas (EUR, JPY, CHF)."
+      },
+      rate: {
+        label: "Tipo",
+        help: "1 unidad de la moneda local de la organización (Localización → Moneda predeterminada) = Tipo unidades de esta moneda. Ejemplo: moneda local USD, moneda EUR, tipo 0,92 significa 1 USD = 0,92 EUR."
+      },
+      effective_date: {
+        label: "Fecha de entrada en vigor",
+        help: "Primera fecha a la que se aplica este tipo. Sigue vigente hasta que una fila posterior de la misma moneda lo sustituya."
+      },
+      source: {
+        label: "Origen",
+        help: "Cómo llegó la fila: introducida en Setup (manual), cargada desde un archivo (importación) o escrita por un flujo de una aplicación (aplicación).",
+        options: {
+          manual: "Manual",
+          import: "Importación",
+          app: "Aplicación"
+        }
+      }
+    },
+    _views: {
+      all_rates: {
+        label: "Todos",
+        description: "1 unidad de la moneda local de la organización (Localización → Moneda predeterminada) = Tipo unidades de esta moneda. Ejemplo: moneda local USD, moneda EUR, tipo 0,92 significa 1 USD = 0,92 EUR.",
+        emptyState: {
+          title: "Aún no hay tipos de cambio",
+          message: "Añade una fila por moneda para cada fecha en que cambie su tipo, por ejemplo una fila por moneda al inicio de cada mes."
+        }
+      }
+    }
   }
 };