diff --git a/UAT_PLAYBOOK.md b/UAT_PLAYBOOK.md
index f0e1037..cf80f3f 100644
--- a/UAT_PLAYBOOK.md
+++ b/UAT_PLAYBOOK.md
@@ -125,6 +125,12 @@ CUSTOMER=$(kubectl get secret seed-uat-passwords -n groombook-uat \
 | TC-API-3.17 | Get pet profile summary — groomer restricted | GET /api/pets/{id}/profile-summary as groomer with no pet linkage | 403 Forbidden |
 | TC-API-3.18 | Get pet profile summary — visitCount returns full count | GET /api/pets/{id}/profile-summary with 2+ completed appointments | visitCount >= 2 (not capped at 1) |
 | TC-API-3.19 | Get pet profile summary — upcomingAppointment excludes past | GET /api/pets/{id}/profile-summary with a past confirmed/scheduled appointment | upcomingAppointment is null (past appointments filtered by startTime >= now) |
+| TC-API-3.19a | Get pet profile summary — customer owner-bypass (GRO-2013) | Sign in as `uat-customer@groombook.dev`; `POST /api/portal/session-from-auth`; then `GET /api/pets/{ownPetId}/profile-summary` with header `X-Impersonation-Session-Id: {sessionId}` for either of the customer's seeded pets (`c0000001-0000-0000-0000-000000000002` UAT Pup Alpha, `c0000001-0000-0000-0000-000000000003` UAT Pup Beta) | 200 OK, aggregated profile returned (owner-bypass: customer with valid portal session for pet's clientId is allowed even though rbac.ts auto-provisions them as a `groomer` staff row with no appointment linkage) |
+| TC-API-3.19b | Get pet profile summary — customer cross-tenant blocked (GRO-2013) | Sign in as `uat-customer@groombook.dev`; reuse the customer's sessionId from TC-API-3.19a; `GET /api/pets/{otherClientPetId}/profile-summary` for a pet owned by a different client (`c0000002-...` or any non-customer pet) | 403 Forbidden (owner-bypass requires session.clientId === pet.clientId) |
+| TC-API-3.19c | Get pet profile summary — customer without portal session header | Same as TC-API-3.19a but omit the `X-Impersonation-Session-Id` header | 403 Forbidden (no owner-bypass without valid portal session) |
+| TC-API-3.29 | Get pet profile summary — unknown UUID returns 404 (GRO-2014) | GET /api/pets/00000000-0000-0000-0000-000000000001/profile-summary while authenticated (any role) | 404 Not Found with body `{"error":"Not found"}` (was empty-body 500 in GRO-2014) |
+| TC-API-3.30 | Get pet profile summary — malformed UUID returns 404 (GRO-2014) | GET /api/pets/not-a-uuid/profile-summary while authenticated | 404 Not Found with body `{"error":"Not found"}` (was empty-body 500 in GRO-2014 — Postgres uuid cast failure) |
+| TC-API-3.31 | Get pet profile summary — never empty-body 500 (GRO-2014) | GET /api/pets/{anyId}/profile-summary across the test sweep | No response has status 500 with an empty body. Any 500 must include a JSON body `{"error":"Internal Server Error"}` |
 
 #### Seed Data Verification (GRO-1898)
 
diff --git a/apps/api/src/__tests__/petProfileSummary.test.ts b/apps/api/src/__tests__/petProfileSummary.test.ts
index f7e5686..91fe3bb 100644
--- a/apps/api/src/__tests__/petProfileSummary.test.ts
+++ b/apps/api/src/__tests__/petProfileSummary.test.ts
@@ -44,6 +44,7 @@ interface MockState {
   groomingLogs: Record<string, unknown>[];
   staffMembers: Record<string, unknown>[];
   services: Record<string, unknown>[];
+  impersonationSessions: Record<string, unknown>[];
 }
 
 let mock: MockState;
@@ -168,6 +169,19 @@ function resetMock() {
       { id: "service-1", name: "Full Groom", description: null, basePriceCents: 6000, durationMinutes: 120, active: true, createdAt: new Date(), updatedAt: new Date() },
       { id: "service-2", name: "Bath & Brush", description: null, basePriceCents: 4000, durationMinutes: 60, active: true, createdAt: new Date(), updatedAt: new Date() },
     ],
+    impersonationSessions: [
+      {
+        id: "sess-owner",
+        staffId: "staff-groomer-id",
+        clientId: CLIENT_ID,
+        reason: "sso-bridge",
+        status: "active",
+        startedAt: new Date("2024-11-01"),
+        endedAt: null,
+        expiresAt: new Date("2099-01-01T00:00:00Z"),
+        createdAt: new Date("2024-11-01"),
+      },
+    ],
   };
 }
 
@@ -177,6 +191,7 @@ vi.mock("../db/index.js", () => {
   const groomingVisitLogs = new Proxy({ _name: "groomingVisitLogs" }, { get: (t, p) => p === "_name" ? "groomingVisitLogs" : {} });
   const staff = new Proxy({ _name: "staff" }, { get: (t, p) => p === "_name" ? "staff" : {} });
   const services = new Proxy({ _name: "services" }, { get: (t, p) => p === "_name" ? "services" : {} });
+  const impersonationSessions = new Proxy({ _name: "impersonationSessions" }, { get: (t, p) => p === "_name" ? "impersonationSessions" : {} });
 
   // Tracks { [tableName]: { [alias]: SQLExpression } } for the current select() call
   let selectedColumns: Record<string, Record<string, unknown>> = {};
@@ -248,6 +263,7 @@ vi.mock("../db/index.js", () => {
             if (name === "groomingVisitLogs") return makeChainable(mock.groomingLogs);
             if (name === "staff") return makeChainable(mock.staffMembers);
             if (name === "services") return makeChainable(mock.services);
+            if (name === "impersonationSessions") return makeChainable(mock.impersonationSessions);
             return makeChainable([]);
           },
         };
@@ -261,6 +277,7 @@ vi.mock("../db/index.js", () => {
     groomingVisitLogs,
     staff,
     services,
+    impersonationSessions,
     and: vi.fn((a: unknown, b: unknown) => [a, b]),
     desc: vi.fn((c: unknown) => c),
     eq: vi.fn((_col: unknown, _val: unknown) => ({ col: _col, val: _val })),
@@ -399,4 +416,102 @@ describe("GET /:id/profile-summary — empty history", () => {
     expect(body.recentGroomingHistory).toEqual([]);
     expect(body.lastVisitDate).toBeNull();
   });
+});
+
+describe("GET /:id/profile-summary — owner-bypass via X-Impersonation-Session-Id (GRO-2013)", () => {
+  beforeEach(resetMock);
+
+  // Simulates the rbac.ts auto-provisioned "groomer" that a customer gets on first login:
+  // role=groomer, no linkage to any appointment.
+  const CUSTOMER_STAFF: StaffRow = {
+    id: "staff-customer-id",
+    oidcSub: null,
+    userId: "user-customer-id",
+    role: "groomer",
+    isSuperUser: false,
+    name: "UAT Customer",
+    email: "uat-customer@groombook.dev",
+    active: true,
+    icalToken: null,
+    createdAt: new Date(),
+    updatedAt: new Date(),
+  };
+
+  it("customer with valid portal session for pet's client returns 200 (owner-bypass)", async () => {
+    const app = makeApp(CUSTOMER_STAFF);
+    // Groomer has no appointment linkage — proves the bypass is via portal session, not linkage.
+    mock.appointments = [];
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`, {
+      headers: { "X-Impersonation-Session-Id": "sess-owner" },
+    });
+    expect(res.status).toBe(200);
+    const body = await res.json();
+    expect(body.id).toBe(PET_ID);
+    expect(body.name).toBe("Biscuit");
+    expect(body.clientId).toBe(CLIENT_ID);
+  });
+
+  it("customer without X-Impersonation-Session-Id header still gets 403 (no bypass)", async () => {
+    const app = makeApp(CUSTOMER_STAFF);
+    mock.appointments = [];
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`);
+    expect(res.status).toBe(403);
+  });
+
+  it("customer with portal session for a DIFFERENT client gets 403 (cross-tenant blocked)", async () => {
+    const app = makeApp(CUSTOMER_STAFF);
+    mock.appointments = [];
+    mock.impersonationSessions = [
+      {
+        id: "sess-other-client",
+        staffId: "staff-customer-id",
+        clientId: "00000000-0000-0000-0000-000000000099", // different from CLIENT_ID
+        reason: "sso-bridge",
+        status: "active",
+        startedAt: new Date("2024-11-01"),
+        endedAt: null,
+        expiresAt: new Date("2099-01-01T00:00:00Z"),
+        createdAt: new Date("2024-11-01"),
+      },
+    ];
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`, {
+      headers: { "X-Impersonation-Session-Id": "sess-other-client" },
+    });
+    expect(res.status).toBe(403);
+  });
+
+  it("customer with expired portal session still gets 403", async () => {
+    const app = makeApp(CUSTOMER_STAFF);
+    mock.appointments = [];
+    mock.impersonationSessions = [
+      {
+        id: "sess-expired",
+        staffId: "staff-customer-id",
+        clientId: CLIENT_ID,
+        reason: "sso-bridge",
+        status: "active",
+        startedAt: new Date("2024-01-01"),
+        endedAt: null,
+        expiresAt: new Date("2024-02-01T00:00:00Z"), // expired long ago
+        createdAt: new Date("2024-01-01"),
+      },
+    ];
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`, {
+      headers: { "X-Impersonation-Session-Id": "sess-expired" },
+    });
+    expect(res.status).toBe(403);
+  });
+
+  it("manager does NOT need the impersonation header (existing role check still works)", async () => {
+    const app = makeApp(MANAGER);
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`);
+    expect(res.status).toBe(200);
+  });
+
+  it("groomer with linkage to pet's client still works (regression — no regression from bypass)", async () => {
+    const app = makeApp(GROOMER);
+    // GROOMER fixture has appointments linked to staff-groomer-id in the mock state
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`);
+    expect(res.status).toBe(200);
+  });
 });
\ No newline at end of file
diff --git a/apps/api/src/routes/pets.ts b/apps/api/src/routes/pets.ts
index f8b6440..d678f6f 100644
--- a/apps/api/src/routes/pets.ts
+++ b/apps/api/src/routes/pets.ts
@@ -1,7 +1,7 @@
 import { Hono } from "hono";
 import { zValidator } from "@hono/zod-validator";
 import { z } from "zod/v3";
-import { and, desc, eq, exists, getDb, gte, groomingVisitLogs, or, pets, appointments, staff, services, sql } from "../db/index.js";
+import { and, desc, eq, exists, getDb, gte, groomingVisitLogs, impersonationSessions, or, pets, appointments, staff, services, sql } from "../db/index.js";
 import type { AppEnv } from "../middleware/rbac.js";
 import {
   getPresignedUploadUrl,
@@ -307,10 +307,38 @@ async function groomerLinkageCheck(
   return !!linkage;
 }
 
+/**
+ * Resolves the clientId from the X-Impersonation-Session-Id header, if present and active.
+ * Used by staff routes to allow a customer (auto-provisioned as a `groomer` staff row
+ * by rbac.ts) to access their own pet's data when they are the rightful owner.
+ *
+ * Returns null when the header is missing, the session is unknown/expired/ended, or the
+ * session exists but has no clientId — callers should treat null as "no owner-bypass".
+ */
+async function resolveImpersonationClientId(
+  db: ReturnType<typeof getDb>,
+  c: { req: { header: (name: string) => string | undefined } }
+): Promise<string | null> {
+  const sessionId = c.req.header("X-Impersonation-Session-Id");
+  if (!sessionId) return null;
+  const [session] = await db
+    .select({ clientId: impersonationSessions.clientId, status: impersonationSessions.status, expiresAt: impersonationSessions.expiresAt })
+    .from(impersonationSessions)
+    .where(eq(impersonationSessions.id, sessionId))
+    .limit(1);
+  if (!session) return null;
+  if (session.status !== "active") return null;
+  if (session.expiresAt <= new Date()) return null;
+  return session.clientId;
+}
+
 /**
  * GET /:id/profile-summary
  * Returns aggregated profile: basic pet fields + grooming history + visit stats + upcoming appointment.
  * Groomer RBAC: same visibility rules as GET /:id.
+ * Owner-bypass (GRO-2013): a customer who supplies a valid X-Impersonation-Session-Id
+ * for the pet's owning client may read their own pet's summary, even though rbac.ts
+ * auto-provisions them as a `groomer` staff row with no appointment linkage.
  */
 petsRouter.get("/:id/profile-summary", async (c) => {
   const db = getDb();
@@ -321,7 +349,15 @@ petsRouter.get("/:id/profile-summary", async (c) => {
   const [row] = await db.select().from(pets).where(eq(pets.id, petId));
   if (!row) return c.json({ error: "Not found" }, 404);
 
+  // Owner-bypass: customer with a valid portal session for this pet's client
+  // is allowed to view their own pet's profile summary (GRO-2013).
+  let isOwner = false;
   if (isGroomer) {
+    const ownerClientId = await resolveImpersonationClientId(db, c);
+    isOwner = !!ownerClientId && ownerClientId === row.clientId;
+  }
+
+  if (isGroomer && !isOwner) {
     const hasLinkage = await groomerLinkageCheck(db, row.clientId, staffRow);
     if (!hasLinkage) return c.json({ error: "Forbidden" }, 403);
   }
diff --git a/packages/db/migrations/0039_extend_pet_profile_columns_idempotent.sql b/packages/db/migrations/0039_extend_pet_profile_columns_idempotent.sql
new file mode 100644
index 0000000..f38869b
--- /dev/null
+++ b/packages/db/migrations/0039_extend_pet_profile_columns_idempotent.sql
@@ -0,0 +1,27 @@
+-- Migration: 0039_extend_pet_profile_columns_idempotent.sql
+-- GRO-2033: re-register the temperament/medical/preferred-cuts columns from
+-- 0034 with an idempotent ADD COLUMN IF NOT EXISTS + a monotonic journal
+-- `when` (1780000000001), above the 0033 high-water mark (1779500000000)
+-- and above the most recent applied migration 0038 (1780000000000).
+--
+-- 0034_extend_pet_profile_columns.sql was authored on 2026-05-28 with
+-- `when` = 1751140800000 (2025-06-28) — *below* the 0033 high-water mark
+-- of 1779500000000 (2026-05-23). drizzle-orm@0.38.4
+-- (pg-core/dialect.js#migrate) only applies a migration when
+-- `migration.folderMillis > lastDbMigration.created_at`, so on prod —
+-- whose last applied entry was 0033 at created_at=1779500000000 — 0034
+-- was silently skipped, leaving `pets.temperament_score` (and friends)
+-- missing. The migrate Job still exits 0 ("migrations applied
+-- successfully!") because the journal high watermark *was* advanced by
+-- 0038, but no schema change ever ran for 0034. Seed/reset then crash on:
+--   PostgresError: column "temperament_score" does not exist (42703)
+--
+-- Same pattern as GRO-1999 (0037 → 0038): do NOT modify 0034 in-place
+-- (UAT/dev have already applied it via their lower watermarks). Add a
+-- new idempotent migration with a monotonic `when` instead so existing
+-- DBs apply it cleanly and fresh DBs are a no-op-after-no-op.
+
+ALTER TABLE "pets" ADD COLUMN IF NOT EXISTS "temperament_score" integer;
+ALTER TABLE "pets" ADD COLUMN IF NOT EXISTS "temperament_flags" jsonb DEFAULT '[]';
+ALTER TABLE "pets" ADD COLUMN IF NOT EXISTS "medical_alerts" jsonb DEFAULT '[]';
+ALTER TABLE "pets" ADD COLUMN IF NOT EXISTS "preferred_cuts" jsonb DEFAULT '[]';
diff --git a/packages/db/migrations/0040_register_missing_coat_type_values.sql b/packages/db/migrations/0040_register_missing_coat_type_values.sql
new file mode 100644
index 0000000..88ff7ec
--- /dev/null
+++ b/packages/db/migrations/0040_register_missing_coat_type_values.sql
@@ -0,0 +1,26 @@
+-- Migration: 0040_register_missing_coat_type_values.sql
+-- GRO-2033: re-register the 'short' / 'medium' / 'silky' coat_type enum
+-- values that 0036 added with `when` = 1751480000000 — *below* the 0033
+-- high-water mark of 1779500000000. drizzle-orm@0.38.4
+-- (pg-core/dialect.js#migrate) silently skipped 0036 on prod for the same
+-- reason it skipped 0034 (see 0039). 0036 itself was idempotent
+-- (`ADD VALUE IF NOT EXISTS`), but its journal entry was never applied,
+-- so the values are not in the prod enum.
+--
+-- Same pattern as GRO-1999 (0037 → 0038) and 0039: do NOT modify 0036 in
+-- place. Add a new entry with a monotonic `when` (1780000000002) so
+-- existing prod re-applies it; UAT/dev are a safe no-op because the
+-- statements are `IF NOT EXISTS` and the values are already there.
+--
+-- Postgres restriction: `ALTER TYPE ... ADD VALUE` cannot run inside a
+-- transaction block, so we emit individual auto-commit DDL statements
+-- (no BEGIN/COMMIT). drizzle-kit migrate executes inside a tx; with
+-- `ADD VALUE IF NOT EXISTS` Postgres is permissive and treats it as a
+-- regular DDL statement that *can* run inside a tx in 9.6+ when no new
+-- value is actually added. If you ever rename this to add a value that
+-- doesn't exist on every target DB, lift it out of the journal
+-- transaction (single-statement file) — see GRO-1999 commit 423d4bf.
+
+ALTER TYPE "coat_type" ADD VALUE IF NOT EXISTS 'short';
+ALTER TYPE "coat_type" ADD VALUE IF NOT EXISTS 'medium';
+ALTER TYPE "coat_type" ADD VALUE IF NOT EXISTS 'silky';
diff --git a/packages/db/migrations/meta/_journal.json b/packages/db/migrations/meta/_journal.json
index 0645748..47e54de 100644
--- a/packages/db/migrations/meta/_journal.json
+++ b/packages/db/migrations/meta/_journal.json
@@ -267,6 +267,20 @@
       "when": 1780000000000,
       "tag": "0038_register_extra_large_pet_size_category",
       "breakpoints": true
+    },
+    {
+      "idx": 39,
+      "version": "7",
+      "when": 1780000000001,
+      "tag": "0039_extend_pet_profile_columns_idempotent",
+      "breakpoints": true
+    },
+    {
+      "idx": 40,
+      "version": "7",
+      "when": 1780000000002,
+      "tag": "0040_register_missing_coat_type_values",
+      "breakpoints": true
     }
   ]
 }
diff --git a/src/__tests__/petProfileSummary.test.ts b/src/__tests__/petProfileSummary.test.ts
new file mode 100644
index 0000000..069d1cb
--- /dev/null
+++ b/src/__tests__/petProfileSummary.test.ts
@@ -0,0 +1,569 @@
+/**
+ * Pet Profile Summary Tests
+ *
+ * Covers GET /api/pets/:id/profile-summary in the deployed tree (root src/).
+ *
+ * Two suites share one mock harness:
+ *
+ *   1. GRO-2013 owner-bypass (the deployed-tree port of #135):
+ *      A customer who is auto-provisioned as a `groomer` staff row by rbac.ts
+ *      (with no appointment linkage) may still read their own pet's summary
+ *      when they supply a valid X-Impersonation-Session-Id whose clientId
+ *      matches the pet's clientId.
+ *
+ *   2. GRO-2014 error handling (deployed tree):
+ *      - Empty-body 500 must never escape the route — the onError handler
+ *        converts unhandled errors into a structured JSON 500.
+ *      - Malformed UUIDs must return 404 (not 500 via a Postgres uuid cast).
+ *      - Missing staff context must return 401 (not TypeError on staffRow.id).
+ *      - Pet not found must return 404.
+ *      - Groomer with no appointment linkage must return 403.
+ *      - Manager and groomer with linkage must receive the summary body.
+ *
+ * Deployed tree handler: src/routes/pets.ts. The mock queries the
+ * `appointments` table (the live schema) for visit history, not
+ * `groomingVisitLogs`.
+ */
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { Hono } from "hono";
+import type { AppEnv, StaffRow } from "../middleware/rbac.js";
+
+// ─── Staff fixtures ──────────────────────────────────────────────────────────
+
+const MANAGER: StaffRow = {
+  id: "staff-manager-id",
+  oidcSub: "oidc-manager-sub",
+  userId: null,
+  role: "manager",
+  isSuperUser: true,
+  name: "Manager McManager",
+  email: "manager@example.com",
+  active: true,
+  icalToken: null,
+  createdAt: new Date(),
+  updatedAt: new Date(),
+};
+
+const GROOMER: StaffRow = {
+  ...MANAGER,
+  id: "staff-groomer-id",
+  oidcSub: "oidc-groomer-sub",
+  role: "groomer",
+  isSuperUser: false,
+  name: "Groomer Gary",
+  email: "groomer@example.com",
+};
+
+/**
+ * Mirrors the auto-provisioned "groomer" staff row rbac.ts creates for an
+ * OIDC user (e.g. uat-customer@groombook.dev) on first login: role=groomer,
+ * no appointment linkage.
+ */
+const CUSTOMER_STAFF: StaffRow = {
+  ...MANAGER,
+  id: "staff-customer-id",
+  oidcSub: null,
+  userId: "user-customer-id",
+  role: "groomer",
+  name: "UAT Customer",
+  email: "uat-customer@groombook.dev",
+};
+
+// ─── Mutable mock state ─────────────────────────────────────────────────────
+
+const CLIENT_ID = "c0000001-0000-0000-0000-000000000001";
+const PET_ID = "c0000001-0000-0000-0000-000000000002";
+const OTHER_CLIENT_PET_ID = "c0000002-0000-0000-0000-000000000099";
+const UNKNOWN_PET_UUID = "00000000-0000-0000-0000-000000000001";
+
+const futureDate = () => new Date(Date.now() + 30 * 60_000);
+const pastDate = () => new Date(Date.now() - 5 * 60_000);
+
+function makePet(overrides: Record<string, unknown> = {}) {
+  return {
+    id: PET_ID,
+    clientId: CLIENT_ID,
+    name: "Biscuit",
+    species: "dog",
+    breed: "Golden Retriever",
+    weightKg: "30.00",
+    dateOfBirth: null,
+    healthAlerts: null,
+    groomingNotes: null,
+    cutStyle: null,
+    shampooPreference: null,
+    specialCareNotes: null,
+    customFields: {},
+    petSizeCategory: "large",
+    coatType: "double",
+    photoKey: null,
+    photoUploadedAt: null,
+    createdAt: new Date("2024-01-01"),
+    updatedAt: new Date("2024-01-01"),
+    ...overrides,
+  };
+}
+
+function makeAppointment(overrides: Record<string, unknown> = {}) {
+  return {
+    id: "appt-1",
+    clientId: CLIENT_ID,
+    petId: PET_ID,
+    serviceId: "service-1",
+    staffId: GROOMER.id,
+    batherStaffId: null,
+    status: "completed",
+    startTime: new Date("2024-06-01T09:00:00Z"),
+    endTime: new Date("2024-06-01T11:00:00Z"),
+    notes: null,
+    priceCents: 6000,
+    seriesId: null,
+    seriesIndex: null,
+    groupId: null,
+    confirmationStatus: "confirmed",
+    confirmedAt: null,
+    cancelledAt: null,
+    confirmationToken: null,
+    customerNotes: null,
+    createdAt: new Date("2024-05-15"),
+    updatedAt: new Date("2024-05-15"),
+    ...overrides,
+  };
+}
+
+function makeService(overrides: Record<string, unknown> = {}) {
+  return {
+    id: "service-1",
+    name: "Full Groom",
+    description: null,
+    basePriceCents: 6000,
+    durationMinutes: 120,
+    active: true,
+    createdAt: new Date(),
+    updatedAt: new Date(),
+    ...overrides,
+  };
+}
+
+function makeSession(overrides: Record<string, unknown> = {}) {
+  return {
+    id: "sess-owner",
+    staffId: CUSTOMER_STAFF.id,
+    clientId: CLIENT_ID,
+    reason: "sso-bridge",
+    status: "active",
+    startedAt: new Date(),
+    endedAt: null,
+    expiresAt: futureDate(),
+    createdAt: new Date(),
+    ...overrides,
+  };
+}
+
+// ─── DB mock state ──────────────────────────────────────────────────────────
+
+let petsTable: Record<string, unknown>[];
+let appointmentsTable: Record<string, unknown>[];
+let servicesTable: Record<string, unknown>[];
+let sessionsTable: Record<string, unknown>[];
+
+// selectQueue: queries resolve in FIFO order. Each .from(table) result
+// returns a chain that resolves to the next queued row set on a terminal
+// call (.where()/.orderBy()/.limit()).
+//
+// A queued entry of `{ table: "pets", rows: null, throw: "..." }` tells the
+// mock to throw instead of returning rows — used by the GRO-2014 "JSON
+// envelope on downstream error" test. Any other queued entry with `rows`
+// resolves to those rows. An entry with `rows: []` returns an empty array
+// (no rows, no throw).
+let selectQueue: Array<{
+  table: string;
+  rows: unknown[] | null;
+  throw?: string;
+}> = [];
+
+function enqueue(table: string, rows: unknown[] = []) {
+  selectQueue.push({ table, rows });
+}
+
+function enqueueThrow(table: string, message: string) {
+  selectQueue.push({ table, rows: null, throw: message });
+}
+
+function resetMock() {
+  petsTable = [makePet()];
+  appointmentsTable = [makeAppointment()];
+  servicesTable = [makeService()];
+  sessionsTable = [makeSession()];
+  selectQueue = [];
+}
+
+// ─── Module mocks ───────────────────────────────────────────────────────────
+
+vi.mock("@groombook/db", () => {
+  function makeTable(name: string) {
+    return new Proxy(
+      { _name: name },
+      {
+        get(target, prop) {
+          if (prop === "_name") return name;
+          if (prop === "$inferSelect") return {};
+          return { table: name, column: prop };
+        },
+      }
+    );
+  }
+
+  function sqlMock(_strings: TemplateStringsArray, ..._params: unknown[]) {
+    const queryString = _strings[0];
+    return {
+      queryChunks: [queryString],
+      as: (alias: string) => ({
+        queryChunks: [queryString],
+        fieldAlias: alias,
+        getSQL() { return this.queryChunks; },
+      }),
+    };
+  }
+
+  function takeQueuedRows(tableName: string): unknown[] {
+    const next = selectQueue.shift();
+    if (next && next.table === tableName) {
+      if (next.throw) {
+        throw new Error(next.throw);
+      }
+      return next.rows ?? [];
+    }
+    return [];
+  }
+
+  // Wrap a finalised result in a Proxy that exposes chainable methods
+  // and the resolved rows. Each call to a chainable method (where/orderBy/
+  // limit/...) returns the SAME rows so the route's natural await on the
+  // chain resolves to the queued data.
+  function wrapRows(rows: unknown[]): unknown {
+    return new Proxy(rows, {
+      get(target, prop: string | symbol) {
+        if (prop === "where" || prop === "orderBy" || prop === "limit"
+          || prop === "leftJoin" || prop === "innerJoin" || prop === "from") {
+          return () => wrapRows(rows);
+        }
+        if (prop === "then") {
+          return (onFulfilled?: (v: unknown) => unknown, onRejected?: (e: unknown) => unknown) =>
+            Promise.resolve(rows).then(onFulfilled, onRejected);
+        }
+        if (prop === Symbol.iterator) {
+          return function* () { for (const v of target) yield v; };
+        }
+        if (prop === Symbol.asyncIterator) {
+          return async function* () { for (const v of target) yield v; };
+        }
+        // @ts-expect-error proxy access
+        return target[prop];
+      },
+    });
+  }
+
+  return {
+    getDb: () => ({
+      select: (_cols?: Record<string, unknown>) => ({
+        from: (table: { _name?: string }) => wrapRows(takeQueuedRows(table._name ?? "")),
+      }),
+      insert: () => ({ values: () => ({ returning: () => [{}] }) }),
+      update: () => ({ set: () => ({ where: () => ({ returning: () => [{}] }) }) }),
+      delete: () => ({ where: () => ({ returning: () => [{}] }) }),
+    }),
+    pets: makeTable("pets"),
+    appointments: makeTable("appointments"),
+    staff: makeTable("staff"),
+    services: makeTable("services"),
+    impersonationSessions: makeTable("impersonationSessions"),
+    and: vi.fn((..._args: unknown[]) => ({})),
+    desc: vi.fn((c: unknown) => c),
+    eq: vi.fn((_a: unknown, _b: unknown) => ({})),
+    exists: vi.fn(() => true),
+    or: vi.fn((..._args: unknown[]) => ({})),
+    sql: sqlMock,
+  };
+});
+
+vi.mock("../lib/s3.js", () => ({
+  getPresignedUploadUrl: vi.fn(),
+  getPresignedGetUrl: vi.fn(),
+  deleteObject: vi.fn(),
+}));
+
+// ─── Import after mocks are set up ──────────────────────────────────────────
+
+const { petsRouter } = await import("../routes/pets.js");
+
+// ─── App builder ────────────────────────────────────────────────────────────
+
+function buildApp(staffRow: StaffRow | null) {
+  const app = new Hono<AppEnv>();
+  app.use("*", async (c, next) => {
+    if (staffRow) {
+      c.set("jwtPayload", { sub: staffRow.oidcSub ?? staffRow.userId ?? "" });
+      c.set("staff", staffRow);
+    }
+    await next();
+  });
+  app.route("/pets", petsRouter);
+  return app;
+}
+
+// ─── Reset before each test ─────────────────────────────────────────────────
+
+beforeEach(() => {
+  resetMock();
+  vi.clearAllMocks();
+});
+
+// ─── GRO-2014 error-handling suite ──────────────────────────────────────────
+
+describe("GET /:id/profile-summary — GRO-2014 error handling", () => {
+  it("returns 404 (not 500) for a malformed UUID path param", async () => {
+    const app = buildApp(MANAGER);
+    const res = await app.request("/pets/not-a-uuid/profile-summary");
+    expect(res.status).toBe(404);
+    const body = (await res.json()) as { error: string };
+    expect(body.error).toBe("Not found");
+  });
+
+  it("returns 401 when staff context is missing (defense in depth)", async () => {
+    const app = buildApp(null);
+    const res = await app.request(`/pets/${UNKNOWN_PET_UUID}/profile-summary`);
+    expect(res.status).toBe(401);
+    const body = (await res.json()) as { error: string };
+    expect(body.error).toBe("Unauthorized");
+  });
+
+  it("returns 404 when authenticated and pet does not exist", async () => {
+    enqueue("pets", []);
+    const app = buildApp(MANAGER);
+    const res = await app.request(`/pets/${UNKNOWN_PET_UUID}/profile-summary`);
+    expect(res.status).toBe(404);
+    const body = (await res.json()) as { error: string };
+    expect(body.error).toBe("Not found");
+  });
+
+  it("returns 403 when groomer has no appointment linkage to the pet's client", async () => {
+    enqueue("pets", petsTable);
+    enqueue("appointments", []); // linkage check returns empty → 403
+    const app = buildApp(GROOMER);
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`);
+    expect(res.status).toBe(403);
+    const body = (await res.json()) as { error: string };
+    expect(body.error).toBe("Forbidden");
+  });
+
+  it("returns 200 with summary for a manager (no groomer linkage check)", async () => {
+    enqueue("pets", petsTable);
+    enqueue("appointments", appointmentsTable); // history
+    enqueue("appointments", [{ count: 1 }]);    // visit count
+    enqueue("appointments", []);                // upcoming (none)
+    const app = buildApp(MANAGER);
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`);
+    expect(res.status).toBe(200);
+    const body = (await res.json()) as Record<string, unknown>;
+    expect(body.id).toBe(PET_ID);
+    expect(body.name).toBe("Biscuit");
+    expect(body.visitCount).toBe(1);
+    expect(body.upcomingAppointment).toBeNull();
+    expect(body.recentGroomingHistory).toBeInstanceOf(Array);
+  });
+
+  it("returns 200 with summary for a groomer with appointment linkage", async () => {
+    enqueue("pets", petsTable);
+    enqueue("appointments", [{ id: "appt-1" }]); // linkage found
+    enqueue("appointments", appointmentsTable);  // history
+    enqueue("appointments", [{ count: 1 }]);     // visit count
+    enqueue("appointments", []);                 // upcoming
+    const app = buildApp(GROOMER);
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`);
+    expect(res.status).toBe(200);
+    const body = (await res.json()) as Record<string, unknown>;
+    expect(body.id).toBe(PET_ID);
+  });
+
+  it("returns a JSON envelope (not empty body) when a downstream query throws", async () => {
+    enqueueThrow("pets", "simulated postgres uuid cast failure");
+    const app = buildApp(MANAGER);
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`);
+    expect(res.status).toBe(500);
+    const body = (await res.json()) as { error: string };
+    expect(body.error).toBe("Internal Server Error");
+  });
+});
+
+// ─── GRO-2013 owner-bypass suite ────────────────────────────────────────────
+
+describe("GET /:id/profile-summary — owner-bypass (GRO-2013)", () => {
+  it("returns 404 when the pet does not exist", async () => {
+    enqueue("pets", []);
+    const app = buildApp(MANAGER);
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`);
+    expect(res.status).toBe(404);
+  });
+
+  it("returns 200 with aggregated profile for a manager", async () => {
+    enqueue("pets", petsTable);
+    enqueue("appointments", appointmentsTable);
+    enqueue("appointments", [{ count: 1 }]);
+    enqueue("appointments", []);
+
+    const app = buildApp(MANAGER);
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`);
+    expect(res.status).toBe(200);
+    const body = await res.json();
+    expect(body.id).toBe(PET_ID);
+    expect(body.name).toBe("Biscuit");
+    expect(body.recentGroomingHistory).toBeInstanceOf(Array);
+    expect(body.visitCount).toBe(1);
+    expect(body.upcomingAppointment).toBeNull();
+  });
+
+  it("returns 200 for a groomer with appointment linkage to the pet's client", async () => {
+    enqueue("pets", petsTable);
+    enqueue("appointments", [{ id: "appt-1" }]); // linkage found
+    enqueue("appointments", appointmentsTable);
+    enqueue("appointments", [{ count: 1 }]);
+    enqueue("appointments", []);
+
+    const app = buildApp(GROOMER);
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`);
+    expect(res.status).toBe(200);
+  });
+
+  it("returns 403 for a groomer with no appointment linkage and no bypass header", async () => {
+    enqueue("pets", petsTable);
+    enqueue("appointments", []); // no linkage
+
+    const app = buildApp(GROOMER);
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`);
+    expect(res.status).toBe(403);
+  });
+
+  it("customer-as-groomer with valid active session for pet's client returns 200", async () => {
+    enqueue("pets", petsTable);
+    enqueue("impersonationSessions", sessionsTable); // active session found
+    enqueue("appointments", appointmentsTable);
+    enqueue("appointments", [{ count: 1 }]);
+    enqueue("appointments", []);
+
+    const app = buildApp(CUSTOMER_STAFF);
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`, {
+      headers: { "X-Impersonation-Session-Id": "sess-owner" },
+    });
+    expect(res.status).toBe(200);
+    const body = await res.json();
+    expect(body.id).toBe(PET_ID);
+  });
+
+  it("customer-as-groomer with no header still gets 403 (no bypass)", async () => {
+    enqueue("pets", petsTable);
+
+    const app = buildApp(CUSTOMER_STAFF);
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`);
+    expect(res.status).toBe(403);
+  });
+
+  it("customer-as-groomer with session for a DIFFERENT client gets 403 (cross-tenant blocked)", async () => {
+    // Session exists but clientId !== pet.clientId → bypass does not apply
+    // → falls through to groomer linkage check → no linkage → 403
+    enqueue("pets", petsTable);
+    enqueue("impersonationSessions", [
+      makeSession({
+        id: "sess-other-client",
+        clientId: "c0000000-0000-0000-0000-000000000099", // different from CLIENT_ID
+      }),
+    ]);
+    enqueue("appointments", []); // no linkage → 403
+
+    const app = buildApp(CUSTOMER_STAFF);
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`, {
+      headers: { "X-Impersonation-Session-Id": "sess-other-client" },
+    });
+    expect(res.status).toBe(403);
+  });
+
+  it("customer-as-groomer with expired session still gets 403", async () => {
+    enqueue("pets", petsTable);
+    enqueue("impersonationSessions", [
+      makeSession({ id: "sess-expired", expiresAt: pastDate() }),
+    ]);
+    enqueue("appointments", []); // no linkage → 403
+
+    const app = buildApp(CUSTOMER_STAFF);
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`, {
+      headers: { "X-Impersonation-Session-Id": "sess-expired" },
+    });
+    expect(res.status).toBe(403);
+  });
+
+  it("customer-as-groomer with ended (status != active) session still gets 403", async () => {
+    enqueue("pets", petsTable);
+    enqueue("impersonationSessions", [
+      makeSession({ id: "sess-ended", status: "ended" }),
+    ]);
+    enqueue("appointments", []); // no linkage → 403
+
+    const app = buildApp(CUSTOMER_STAFF);
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`, {
+      headers: { "X-Impersonation-Session-Id": "sess-ended" },
+    });
+    expect(res.status).toBe(403);
+  });
+
+  it("customer-as-groomer with unknown session id still gets 403", async () => {
+    enqueue("pets", petsTable);
+    enqueue("impersonationSessions", []); // session not found
+    enqueue("appointments", []); // no linkage → 403
+
+    const app = buildApp(CUSTOMER_STAFF);
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`, {
+      headers: { "X-Impersonation-Session-Id": "sess-unknown" },
+    });
+    expect(res.status).toBe(403);
+  });
+
+  it("manager does NOT need the impersonation header (existing role check still works)", async () => {
+    enqueue("pets", petsTable);
+    enqueue("appointments", appointmentsTable);
+    enqueue("appointments", [{ count: 1 }]);
+    enqueue("appointments", []);
+
+    const app = buildApp(MANAGER);
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`);
+    expect(res.status).toBe(200);
+  });
+
+  it("groomer with linkage to pet's client still works (regression — no regression from bypass)", async () => {
+    enqueue("pets", petsTable);
+    enqueue("appointments", [{ id: "appt-1" }]); // linkage found
+    enqueue("appointments", appointmentsTable);
+    enqueue("appointments", [{ count: 1 }]);
+    enqueue("appointments", []);
+
+    const app = buildApp(GROOMER);
+    const res = await app.request(`/pets/${PET_ID}/profile-summary`);
+    expect(res.status).toBe(200);
+  });
+
+  it("owner-bypass: customer cannot view another client's pet (cross-tenant block)", async () => {
+    // The customer has a valid session for CLIENT_ID, but the pet belongs
+    // to a different client → isOwner=false → falls through to groomer
+    // linkage check → 403.
+    enqueue("pets", [
+      makePet({ id: OTHER_CLIENT_PET_ID, clientId: "c0000002-0000-0000-0000-000000000002" }),
+    ]);
+    enqueue("impersonationSessions", sessionsTable); // valid session, but for CLIENT_ID
+    enqueue("appointments", []); // no linkage → 403
+
+    const app = buildApp(CUSTOMER_STAFF);
+    const res = await app.request(`/pets/${OTHER_CLIENT_PET_ID}/profile-summary`, {
+      headers: { "X-Impersonation-Session-Id": "sess-owner" },
+    });
+    expect(res.status).toBe(403);
+  });
+});
diff --git a/src/routes/pets.ts b/src/routes/pets.ts
index ffe494c..45dcde2 100644
--- a/src/routes/pets.ts
+++ b/src/routes/pets.ts
@@ -7,6 +7,7 @@ import {
   eq,
   exists,
   getDb,
+  impersonationSessions,
   or,
   pets,
   appointments,
@@ -23,6 +24,23 @@ import {
 
 export const petsRouter = new Hono<AppEnv>();
 
+// Convert Zod validation errors from 422 to 400 and ensure any thrown error
+// returns a structured JSON body rather than Hono's default empty-body 500.
+// GRO-2014: profile-summary previously bubbled unhandled errors and produced
+// an empty-body 500. Mirror the onError pattern already used in invoices.ts
+// and reports.ts so every error has a JSON envelope.
+petsRouter.onError((err, c) => {
+  if (err instanceof z.ZodError) {
+    return c.json({ error: "Validation failed", issues: err.issues }, 400);
+  }
+  console.error("[pets] unhandled error", err);
+  return c.json({ error: "Internal Server Error" }, 500);
+});
+
+// UUID format used by all pet routes — guards path params against malformed
+// values before they hit Drizzle / Postgres uuid columns (which would throw).
+const uuidSchema = z.string().uuid();
+
 const createPetSchema = z.object({
   clientId: z.string().uuid(),
   name: z.string().min(1).max(200),
@@ -109,18 +127,73 @@ petsRouter.get("/:id", async (c) => {
   return c.json(row);
 });
 
+/**
+ * Resolves the clientId from the X-Impersonation-Session-Id header, if present and active.
+ * Used by staff routes to allow a customer (auto-provisioned as a `groomer` staff row
+ * by rbac.ts) to access their own pet's data when they are the rightful owner.
+ *
+ * Returns null when the header is missing, the session is unknown/expired/ended, or the
+ * session exists but has no clientId — callers should treat null as "no owner-bypass".
+ */
+async function resolveImpersonationClientId(
+  db: ReturnType<typeof getDb>,
+  c: { req: { header: (name: string) => string | undefined } }
+): Promise<string | null> {
+  const sessionId = c.req.header("X-Impersonation-Session-Id");
+  if (!sessionId) return null;
+  const [session] = await db
+    .select({
+      clientId: impersonationSessions.clientId,
+      status: impersonationSessions.status,
+      expiresAt: impersonationSessions.expiresAt,
+    })
+    .from(impersonationSessions)
+    .where(eq(impersonationSessions.id, sessionId))
+    .limit(1);
+  if (!session) return null;
+  if (session.status !== "active") return null;
+  if (session.expiresAt <= new Date()) return null;
+  return session.clientId;
+}
+
 petsRouter.get("/:id/profile-summary", async (c) => {
   const db = getDb();
   const petId = c.req.param("id");
+
+  // GRO-2014: validate UUID format before hitting Postgres. Passing a non-UUID
+  // string to a uuid column makes the driver throw, which previously surfaced
+  // as an empty-body 500 to clients.
+  const parsedId = uuidSchema.safeParse(petId);
+  if (!parsedId.success) {
+    return c.json({ error: "Not found" }, 404);
+  }
+
+  // Defense in depth: resolveStaffMiddleware should always populate `staff`
+  // for protected routes (or short-circuit with 401/403 of its own). Guard
+  // anyway so a misconfigured route mount can't trigger a TypeError on
+  // staffRow.id when the linkage check runs.
   const staffRow = c.get("staff");
-  const isGroomer = staffRow?.role === "groomer";
+  if (!staffRow) {
+    return c.json({ error: "Unauthorized" }, 401);
+  }
+  const isGroomer = staffRow.role === "groomer";
 
   // Fetch the pet
   const [pet] = await db.select().from(pets).where(eq(pets.id, petId));
   if (!pet) return c.json({ error: "Not found" }, 404);
 
-  // Groomer RBAC: check appointment linkage to this pet's client
+  // Owner-bypass (GRO-2013): a customer who supplies a valid
+  // X-Impersonation-Session-Id for the pet's owning client may read their
+  // own pet's summary, even though rbac.ts auto-provisions them as a
+  // `groomer` staff row with no appointment linkage.
+  let isOwner = false;
   if (isGroomer) {
+    const ownerClientId = await resolveImpersonationClientId(db, c);
+    isOwner = !!ownerClientId && ownerClientId === pet.clientId;
+  }
+
+  // Groomer RBAC: check appointment linkage to this pet's client
+  if (isGroomer && !isOwner) {
     const [linkage] = await db
       .select({ id: appointments.id })
       .from(appointments)