diff --git a/.changeset/docs-3003-readonly-server-enforced.md b/.changeset/docs-3003-readonly-server-enforced.md
new file mode 100644
index 0000000000..ae46cf9667
--- /dev/null
+++ b/.changeset/docs-3003-readonly-server-enforced.md
@@ -0,0 +1,16 @@
+---
+'@objectstack/spec': patch
+---
+
+docs(spec): `readonly` is server-enforced on UPDATE, not a UI-only affordance (#3003)
+
+The `readonly` field property was described as "Read-only in UI", which #3003
+proved to be exactly how integrators read it — approval/status/amount columns
+protected only by `readonly: true` were forged with a direct REST `PATCH`,
+self-approving a multi-stage approval on the released 15.0.0. Since #2948 the
+engine strips caller-supplied writes to statically-readonly fields from every
+non-system UPDATE (single-id and multi-row, symmetric with `readonlyWhen`;
+INSERT may still seed the column). The schema description and the field
+liveness ledger now state the server-side contract, and a dogfood conformance
+proof (`showcase-static-readonly.dogfood.test.ts` + an authz-matrix row) pins
+it end-to-end so it cannot silently regress to renderer-only.
diff --git a/content/docs/data-modeling/fields.mdx b/content/docs/data-modeling/fields.mdx
index bfa4d1075f..44770458f8 100644
--- a/content/docs/data-modeling/fields.mdx
+++ b/content/docs/data-modeling/fields.mdx
@@ -280,7 +280,7 @@ These properties are available on all field types:
 | `description` | `string` | — | Developer documentation |
 | `inlineHelpText` | `string` | — | Help text shown in UI |
 | `hidden` | `boolean` | `false` | Hide from default views |
-| `readonly` | `boolean` | `false` | Prevent editing |
+| `readonly` | `boolean` | `false` | Prevent editing — hidden from create/edit forms AND server-enforced: non-system `UPDATE` writes to the field are silently dropped (insert may still seed it) |
 | `sortable` | `boolean` | `true` | Allow sorting by this field |
 | `group` | `string` | — | Group name for organizing in forms (e.g. `'billing'`) |
 
diff --git a/content/docs/data-modeling/validation-rules.mdx b/content/docs/data-modeling/validation-rules.mdx
index a6d011e76c..c437e1c1ec 100644
--- a/content/docs/data-modeling/validation-rules.mdx
+++ b/content/docs/data-modeling/validation-rules.mdx
@@ -27,7 +27,7 @@ These properties apply to **all** field types and are validated by the base `Fie
 | `unique` | `boolean` | `false` | Enforces database-level uniqueness constraint |
 | `multiple` | `boolean` | `false` | Stores value as array (applicable for select, lookup, file, image) |
 | `hidden` | `boolean` | `false` | Excluded from default UI rendering |
-| `readonly` | `boolean` | `false` | Blocks user edits in UI forms |
+| `readonly` | `boolean` | `false` | Blocks user edits in UI forms; server-enforced on update — a non-system write to the field is silently dropped from the payload (insert exempt) |
 | `sortable` | `boolean` | `true` | Whether field appears in list view sort options |
 | `index` | `boolean` | `false` | Creates standard database index |
 | `externalId` | `boolean` | `false` | Marks field as external ID for upsert operations |
diff --git a/packages/dogfood/test/authz-conformance.matrix.ts b/packages/dogfood/test/authz-conformance.matrix.ts
index d12b0a4dfb..48fa69beb3 100644
--- a/packages/dogfood/test/authz-conformance.matrix.ts
+++ b/packages/dogfood/test/authz-conformance.matrix.ts
@@ -77,6 +77,10 @@ export const AUTHZ_CONFORMANCE: AuthzPrimitive[] = [
     note: 'These routes delegate straight to ObjectQL and were only shadowed when the REST plugin registered the same paths FIRST — so the posture depended on plugin registration order (a load-order change silently reopened it, no test failing). Gating each route makes the deny decision a property of this entry point too. Handler-level proof in plugin-hono-server/hono-anonymous-deny.test.ts.' },
   { id: 'default-profile', summary: 'app-declared default profile (isDefault)', state: 'enforced',
     enforcement: 'plugin-security/security-plugin.ts fallback resolution', proof: 'showcase-default-profile.dogfood.test.ts' },
+  { id: 'readonly-static-write', summary: 'static `readonly: true` stripped from non-system UPDATE payloads (#2948 / #3003 — a direct PATCH cannot forge approval/status/amount columns the UI never renders)', state: 'enforced',
+    enforcement: 'objectql/engine.ts update — stripReadonlyFields on both the single-id and multi-row paths (caller-supplied keys only, so audit-hook/middleware server stamps survive; isSystem exempt; symmetric with the readonlyWhen strip)',
+    proof: 'showcase-static-readonly.dogfood.test.ts',
+    note: 'The #3003 field report: `readonly: true` used to be UI-only, so a logged-in non-admin self-approved a 4-stage approval (approval_status/approval_stage/confirmed_total) with one same-session REST PATCH on a draft record — RECORD_LOCKED only guards pending flows, and the draft never entered one. The strip is SILENT (HTTP 200, persisted value kept — reject-vs-strip decided in #2948 for readonlyWhen symmetry). INSERT is deliberately exempt (create may seed a readonly column: defaultValue, import, migration), also symmetric with readonlyWhen. Engine-level unit/integration proof in objectql/plugin.integration.test.ts (#2948 suite: forge stripped, server stamp survives, system context allowed).' },
 
   // ── ADR-0057 — ERP authorization core (enforced + e2e proven) ──────────
   { id: 'scope-depth', summary: 'permission-grant access DEPTH (own/own_and_reports/unit/unit_and_below/org)', state: 'enforced',
diff --git a/packages/dogfood/test/authz-conformance.test.ts b/packages/dogfood/test/authz-conformance.test.ts
index d79545b15f..c52d897c46 100644
--- a/packages/dogfood/test/authz-conformance.test.ts
+++ b/packages/dogfood/test/authz-conformance.test.ts
@@ -80,6 +80,10 @@ const HIGH_RISK = [
   // #2567 — every anonymous-deny HTTP surface is high-risk: it guards the
   // same object data as REST `/data` through a sibling entry point.
   'anonymous-deny-meta', 'anonymous-deny-graphql', 'anonymous-deny-hono-data',
+  // #2948/#3003 — write-integrity face: without the strip, `readonly: true`
+  // is false compliance (declared ≠ enforced) and approval/status columns are
+  // one direct PATCH away from self-approval.
+  'readonly-static-write',
 ];
 
 describe('ADR-0056 D10 — authorization conformance matrix', () => {
diff --git a/packages/dogfood/test/showcase-static-readonly.dogfood.test.ts b/packages/dogfood/test/showcase-static-readonly.dogfood.test.ts
new file mode 100644
index 0000000000..17f05fd442
--- /dev/null
+++ b/packages/dogfood/test/showcase-static-readonly.dogfood.test.ts
@@ -0,0 +1,84 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+//
+// @proof: readonly-static-write
+//
+// #2948 / #3003 — static `readonly: true` is SERVER-enforced on UPDATE, not a
+// UI-only affordance. The #3003 field report: an approval-flow object declared
+// `approval_status` / `approval_stage` as `readonly: true`, the create/edit
+// forms never rendered them — and a logged-in, non-admin user forged all of
+// them (plus an amount column) with one direct REST PATCH from the same
+// session, self-approving a 4-stage approval. The strip added for #2948
+// (`stripReadonlyFields`, objectql/engine.ts) closes exactly that: on a
+// non-system UPDATE, caller-supplied writes to statically-readonly fields are
+// silently dropped (HTTP 200, persisted value kept) — symmetric with the
+// `readonlyWhen` strip. INSERT is deliberately exempt (a create may seed a
+// readonly column: defaultValue, import, migration), matching `readonlyWhen`.
+//
+// Proven here on the REAL showcase app over HTTP: `showcase_contact.lead_score`
+// is the stand-in for the #3003 approval/status/amount columns — readonly,
+// "computed by scoring rules — not user-editable", never on the create form.
+
+import { describe, it, expect, beforeAll, afterAll } from 'vitest';
+import showcaseStack from '@objectstack/example-showcase';
+import { bootStack, type VerifyStack } from '@objectstack/verify';
+
+const OBJ = '/data/showcase_contact';
+const idOf = (b: any) => b?.id ?? b?.record?.id ?? b?.data?.id ?? b?.recordId;
+const recordOf = (b: any) => b?.record ?? b?.data ?? b;
+
+describe('showcase: static readonly write enforcement (#2948 / #3003)', () => {
+  let stack: VerifyStack;
+  let token: string;
+  let contactId: string;
+
+  beforeAll(async () => {
+    stack = await bootStack(showcaseStack);
+    await stack.signIn();
+    token = await stack.signUp('ro-worker@verify.test');
+
+    // INSERT exemption (documented contract, symmetric with `readonlyWhen`):
+    // a create MAY seed a readonly column — the scoring pipeline, an import,
+    // or a migration legitimately writes the initial value.
+    const created = await stack.apiAs(token, 'POST', OBJ, {
+      name: 'Readonly Probe',
+      email: 'ro-probe@verify.test',
+      lead_score: 10,
+    });
+    expect(created.status).toBeLessThan(300);
+    contactId = idOf(await created.json());
+    expect(contactId).toBeTruthy();
+  }, 60_000);
+
+  afterAll(async () => { await stack?.stop(); });
+
+  it('INSERT may seed the readonly field (documented exemption)', async () => {
+    const res = await stack.apiAs(token, 'GET', `${OBJ}/${contactId}`);
+    expect(res.status).toBe(200);
+    expect(recordOf(await res.json()).lead_score, 'insert-seeded value persisted').toBe(10);
+  });
+
+  it('a direct PATCH forging the readonly field is silently stripped — sibling editable fields still land', async () => {
+    // The #3003 move: same logged-in session, straight to the REST API with a
+    // payload the UI would never produce.
+    const forge = await stack.apiAs(token, 'PATCH', `${OBJ}/${contactId}`, {
+      lead_score: 99999,
+      notes: 'legitimate edit in the same payload',
+    });
+    // The strip is SILENT by contract (like `readonlyWhen`): 200, not 4xx.
+    expect(forge.status, 'strip is silent — the request succeeds').toBe(200);
+
+    const after = recordOf(await (await stack.apiAs(token, 'GET', `${OBJ}/${contactId}`)).json());
+    expect(after.lead_score, 'forged readonly value must NOT persist').toBe(10);
+    expect(after.notes, 'editable field from the same payload still lands').toBe(
+      'legitimate edit in the same payload',
+    );
+  });
+
+  it('a PATCH carrying ONLY the forged readonly field is a no-op on the record', async () => {
+    const forge = await stack.apiAs(token, 'PATCH', `${OBJ}/${contactId}`, { lead_score: -1 });
+    expect(forge.status).toBe(200);
+
+    const after = recordOf(await (await stack.apiAs(token, 'GET', `${OBJ}/${contactId}`)).json());
+    expect(after.lead_score, 'readonly value survives an all-forged payload').toBe(10);
+  });
+});
diff --git a/packages/spec/liveness/field.json b/packages/spec/liveness/field.json
index 04f45b96b9..a7454d941d 100644
--- a/packages/spec/liveness/field.json
+++ b/packages/spec/liveness/field.json
@@ -74,7 +74,8 @@
     },
     "readonlyWhen": {
       "status": "live",
-      "note": "renderer CEL."
+      "evidence": "packages/objectql/src/validation/rule-validator.ts",
+      "note": "renderer CEL + server write path: stripReadonlyWhenFields drops UPDATE writes when the predicate is TRUE against {...previous, ...data} (B2); INSERT exempt."
     },
     "visibleWhen": {
       "status": "live",
@@ -86,7 +87,9 @@
     },
     "readonly": {
       "status": "live",
-      "note": "renderer."
+      "evidence": "packages/objectql/src/validation/rule-validator.ts",
+      "proof": "packages/dogfood/test/showcase-static-readonly.dogfood.test.ts#readonly-static-write",
+      "note": "renderer + server write path: stripReadonlyFields drops non-system UPDATE writes to the field (#2948/#3003 — was renderer-only, i.e. false compliance for approval/status columns); INSERT exempt, symmetric with readonlyWhen."
     },
     "hidden": {
       "status": "live",
diff --git a/packages/spec/scripts/liveness/proof-registry.mts b/packages/spec/scripts/liveness/proof-registry.mts
index 9581104567..2c28ab87dc 100644
--- a/packages/spec/scripts/liveness/proof-registry.mts
+++ b/packages/spec/scripts/liveness/proof-registry.mts
@@ -143,6 +143,19 @@ export const HIGH_RISK_CLASSES: HighRiskClass[] = [
     // a declaration whose sweeper stopped running is dead surface (ADR-0049).
     ledgerBindings: [{ type: 'object', path: 'lifecycle' }],
   },
+  {
+    id: 'readonly-static-write',
+    label: 'Static readonly write enforcement',
+    summary:
+      'a statically `readonly: true` field cannot be forged by a non-system UPDATE — the write is stripped server-side, not merely hidden by the form (#2948/#3003: approval/status/amount columns "protected" only by readonly were one direct PATCH away from self-approval).',
+    proofId: 'readonly-static-write',
+    proofRef: 'packages/dogfood/test/showcase-static-readonly.dogfood.test.ts#readonly-static-write',
+    bound: true,
+    // `readonly` was renderer-only until #2948 — declared ≠ enforced is exactly
+    // the false-compliance class ADR-0049 closes. The proof pins the server-side
+    // strip (forge dropped, sibling edit lands, insert exempt) over real HTTP.
+    ledgerBindings: [{ type: 'field', path: 'readonly' }],
+  },
   {
     id: 'form-widget',
     label: 'Form layout / section / widget',
diff --git a/packages/spec/scripts/liveness/proof-registry.test.ts b/packages/spec/scripts/liveness/proof-registry.test.ts
index ab0260152f..2162afd463 100644
--- a/packages/spec/scripts/liveness/proof-registry.test.ts
+++ b/packages/spec/scripts/liveness/proof-registry.test.ts
@@ -104,6 +104,7 @@ describe('registry invariants', () => {
     expect([...BOUND_PROOF_PATHS.keys()].sort()).toEqual(
       [
         'field/type',
+        'field/readonly',
         'flow/nodes.type',
         'flow/runAs',
         'permission/rowLevelSecurity.using',
diff --git a/packages/spec/src/data/field.zod.ts b/packages/spec/src/data/field.zod.ts
index 4b950998c7..b2b379beab 100644
--- a/packages/spec/src/data/field.zod.ts
+++ b/packages/spec/src/data/field.zod.ts
@@ -613,7 +613,7 @@ export const FieldSchema = lazySchema(() => z.object({
 
   /** Security & Visibility */
   hidden: z.boolean().default(false).describe('Hidden from default UI'),
-  readonly: z.boolean().default(false).describe('Read-only in UI'),
+  readonly: z.boolean().default(false).describe('Read-only — never editable in forms, AND server-enforced on UPDATE: a non-system write to this field is silently dropped from the payload (#2948/#3003; symmetric with `readonlyWhen`). INSERT may still seed it (defaultValue, import).'),
 
   /**
    * [ADR-0066 D3] Capabilities required to READ/EDIT this field. A field