diff --git a/SeaHaven.Services/Helpers/WorkOrderMediaAuthorization.cs b/SeaHaven.Services/Helpers/WorkOrderMediaAuthorization.cs
index 5034a0e..2af3080 100644
--- a/SeaHaven.Services/Helpers/WorkOrderMediaAuthorization.cs
+++ b/SeaHaven.Services/Helpers/WorkOrderMediaAuthorization.cs
@@ -6,8 +6,11 @@ namespace SeaHaven.Services.Helpers
 {
     /// <summary>
     /// Claims-derived authorization for work-order media read/mutations.
-    /// True multi-tenant CustomerId/TenantId is not modeled on WorkOrder/JWT;
-    /// scope is role + Assigned (<see cref="WorkOrder.AssignTo"/>) for Technician.
+    /// Organization scope matches the board: callers must already have resolved
+    /// the work order via <c>ApplyBaseScope</c> (non-deleted, non-template).
+    /// Staff may access any in-org work order; technicians only when
+    /// <see cref="WorkOrder.AssignTo"/> matches the actor. See
+    /// <c>docs/adr/0001-work-order-single-org-scope.md</c>.
     /// </summary>
     public static class WorkOrderMediaAuthorization
     {
@@ -51,14 +54,19 @@ namespace SeaHaven.Services.Helpers
         }
 
         /// <summary>
-        /// Staff: any in-scope (non-deleted/non-template) work order.
-        /// Technician: only work orders assigned to the caller. Out-of-scope → NotFound (no disclosure).
+        /// Caller-scope check after a base-scoped (in-org) work-order load.
+        /// Staff: any in-org work order already resolved via <c>ApplyBaseScope</c>.
+        /// Technician: only when assigned to the caller.
+        /// Out of caller scope → NotFound (no disclosure).
         /// </summary>
         public static void EnsureWorkOrderInCallerScope(
             ClaimsPrincipal user,
             string actorId,
             WorkOrder workOrder)
         {
+            // Organization boundary is enforced by the data-layer ApplyBaseScope
+            // load that produced <paramref name="workOrder"/>. Staff are authorized
+            // for any in-org work order (same as the board). See ADR 0001.
             if (IsStaff(user))
                 return;
 
diff --git a/SeaHaven.Services/Implementation/WorkOrderMediaService.cs b/SeaHaven.Services/Implementation/WorkOrderMediaService.cs
index f224388..a75df3e 100644
--- a/SeaHaven.Services/Implementation/WorkOrderMediaService.cs
+++ b/SeaHaven.Services/Implementation/WorkOrderMediaService.cs
@@ -34,6 +34,8 @@ namespace SeaHaven.Services.Implementation
         {
             WorkOrderMediaAuthorization.EnsureCanRead(user, actorId);
 
+            // Organization scope: ApplyBaseScope via Exists / GetWorkOrderForMedia.
+            // Outside org (deleted/template/missing) → null (no disclosure). ADR 0001.
             if (!await _detailData.ExistsAsync(workOrderId, cancellationToken))
                 return null;
 
@@ -257,7 +259,7 @@ namespace SeaHaven.Services.Implementation
             string actorId,
             CancellationToken cancellationToken)
         {
-            // Base-scoped lookup: deleted/template work orders surface as NotFound (no disclosure).
+            // Organization scope via ApplyBaseScope: deleted/template → NotFound (ADR 0001).
             var workOrder = await _mediaData.GetTrackedWorkOrderAsync(workOrderId, cancellationToken);
             if (workOrder == null)
                 throw new WorkOrderBoardValidationException("NotFound", "Work order not found.");
diff --git a/SeaHavenIndustries.Tests/WorkOrderPhase6Tests.cs b/SeaHavenIndustries.Tests/WorkOrderPhase6Tests.cs
index a2e467f..0d2f6fc 100644
--- a/SeaHavenIndustries.Tests/WorkOrderPhase6Tests.cs
+++ b/SeaHavenIndustries.Tests/WorkOrderPhase6Tests.cs
@@ -731,6 +731,57 @@ public class WorkOrderMediaServiceTests
             service.GetMediaAsync(1, AuthenticatedUser(), "actor-1", cts.Token));
     }
 
+    /// <summary>
+    /// Out-of-organization-scope (single-org analogue of SH-116 cross-tenant):
+    /// deleted work orders are outside ApplyBaseScope → null / no media disclosure.
+    /// </summary>
+    [Fact]
+    public async Task GetMedia_StaffOnDeletedWorkOrder_ReturnsNull_OutOfOrgScope()
+    {
+        var (context, service) = CreateSut();
+        context.workOrders.Add(new WorkOrder
+        {
+            Id = 1,
+            IsDeleted = true,
+            BeforPhotoAttachment = "https://example.com/before.jpg"
+        });
+        await context.SaveChangesAsync();
+
+        var media = await service.GetMediaAsync(1, AuthenticatedUser(), "actor-1");
+
+        Assert.Null(media);
+    }
+
+    /// <summary>
+    /// Out-of-organization-scope: template work orders are outside ApplyBaseScope.
+    /// </summary>
+    [Fact]
+    public async Task GetMedia_StaffOnTemplateWorkOrder_ReturnsNull_OutOfOrgScope()
+    {
+        var (context, service) = CreateSut();
+        context.workOrders.Add(new WorkOrder
+        {
+            Id = 1,
+            istemplate = true,
+            BeforPhotoAttachment = "https://example.com/before.jpg"
+        });
+        await context.SaveChangesAsync();
+
+        var media = await service.GetMediaAsync(1, AuthenticatedUser(), "actor-1");
+
+        Assert.Null(media);
+    }
+
+    [Fact]
+    public async Task GetMedia_MissingWorkOrder_ReturnsNull_OutOfOrgScope()
+    {
+        var (_, service) = CreateSut();
+
+        var media = await service.GetMediaAsync(99, AuthenticatedUser(), "actor-1");
+
+        Assert.Null(media);
+    }
+
     [Fact]
     public async Task DeleteMedia_ReadOnlyWorkOrder_Throws()
     {
@@ -937,8 +988,11 @@ public class WorkOrderMediaServiceTests
         Assert.Equal("Forbidden", ex.Code);
     }
 
+    /// <summary>
+    /// Out-of-organization-scope mutation: missing id → NotFound (no disclosure).
+    /// </summary>
     [Fact]
-    public async Task EnsureCanMutateMedia_MissingWorkOrder_ThrowsNotFound()
+    public async Task EnsureCanMutateMedia_MissingWorkOrder_ThrowsNotFound_OutOfOrgScope()
     {
         var (_, service) = CreateSut();
         var ex = await Assert.ThrowsAsync<WorkOrderBoardValidationException>(() =>
@@ -946,8 +1000,11 @@ public class WorkOrderMediaServiceTests
         Assert.Equal("NotFound", ex.Code);
     }
 
+    /// <summary>
+    /// Out-of-organization-scope mutation: deleted WO outside ApplyBaseScope → NotFound.
+    /// </summary>
     [Fact]
-    public async Task EnsureCanMutateMedia_DeletedWorkOrder_ThrowsNotFound()
+    public async Task EnsureCanMutateMedia_DeletedWorkOrder_ThrowsNotFound_OutOfOrgScope()
     {
         var (context, service) = CreateSut();
         context.workOrders.Add(new WorkOrder
@@ -965,8 +1022,11 @@ public class WorkOrderMediaServiceTests
         Assert.Equal("NotFound", ex.Code);
     }
 
+    /// <summary>
+    /// Out-of-organization-scope mutation: template WO outside ApplyBaseScope → NotFound.
+    /// </summary>
     [Fact]
-    public async Task EnsureCanMutateMedia_TemplateWorkOrder_ThrowsNotFound()
+    public async Task EnsureCanMutateMedia_TemplateWorkOrder_ThrowsNotFound_OutOfOrgScope()
     {
         var (context, service) = CreateSut();
         context.workOrders.Add(new WorkOrder
diff --git a/docs/adr/0001-work-order-single-org-scope.md b/docs/adr/0001-work-order-single-org-scope.md
new file mode 100644
index 0000000..4abacc7
--- /dev/null
+++ b/docs/adr/0001-work-order-single-org-scope.md
@@ -0,0 +1,71 @@
+# ADR 0001: Work-order media uses single-org scope (board-aligned)
+
+## Status
+
+Accepted — 2026-08-04
+
+## Context
+
+SH-116 requires that cross-tenant, unauthorized, and out-of-scope media access
+be rejected without metadata disclosure. The repository hard rule
+(`ARCHITECTURE_AND_CODE_QUALITY.md` §2) requires **server-derived tenant
+scope**: filtering by tenant/customer/owner comes from the authenticated
+principal and the data layer, never from client-supplied body/query as the
+source of truth.
+
+The work-order domain does not model `TenantId` / `CustomerId` on `WorkOrder`
+or on JWT claims. The board, search, and detail paths already treat the
+deployment as a single organization: staff see any work order that passes
+`ApplyBaseScope` (non-deleted, non-template). Introducing a multi-tenant key
+would require product modeling plus a schema migration, which is out of scope
+for the SH-116 media contract.
+
+## Decision
+
+Work-order media authorization matches the board:
+
+1. **Organization / “tenant” boundary** = `ApplyBaseScope` in the data layer
+   (`istemplate != true` and not deleted). Lookups outside that set resolve as
+   missing → `NotFound` / null (no disclosure).
+2. **Authorization at service entry** from claims: staff roles
+   (`Admin`, `Manager`, `Dispatcher`, `Supervisor`) may read/mutate any
+   in-org work order; role `User` (technician) only when
+   `WorkOrder.AssignTo == actorId`; delete remains staff-only.
+3. Scope is never taken from request body or query as the trust source;
+   `actorId` and roles come from the authenticated principal.
+
+This satisfies server-derived scope for the current single-org deployment.
+True multi-tenant isolation remains deferred until product models a tenant key
+and emits a matching claim.
+
+## Consequences
+
+- Out-of-organization-scope tests cover deleted, template, and missing work
+  order ids (GET and mutations) as the single-org analogue of SH-116
+  “cross-tenant” rejection.
+- Staff org-wide access by numeric id remains intentional and aligned with the
+  board; it is not a substitute for future multi-tenant keys.
+- Reviewers of media PRs should cite this ADR when evaluating tenant-scope
+  findings against SH-116.
+
+## Excepted / clarified rule
+
+Hard rule: **server-derived tenant scope**
+(`ARCHITECTURE_AND_CODE_QUALITY.md` §2).
+
+Clarification: in the work-order domain, the server-derived scope key is the
+organization boundary enforced by `ApplyBaseScope` plus claims-derived
+role/assignee — not a `TenantId`/`CustomerId` column. Absence of a multi-tenant
+key is an accepted product/architecture state until superseded.
+
+## Review / expiry
+
+Re-review by **2027-02-04**, or earlier if product introduces
+`TenantId`/`CustomerId` on work orders or JWT claims.
+
+## References
+
+- SH-116 — Completion document: fields + media categorization
+- PR that relies on this ADR: Sea-Haven-Industries/shoc-backend#47
+- `WorkOrderBoardQueryFilters.ApplyBaseScope`
+- `WorkOrderMediaAuthorization`