diff --git a/.changeset/metadata-hmr.md b/.changeset/metadata-hmr.md
deleted file mode 100644
index 53a00d310..000000000
--- a/.changeset/metadata-hmr.md
+++ /dev/null
@@ -1,15 +0,0 @@
----
-"@objectstack/metadata": patch
-"@objectstack/studio": patch
-"@objectstack/cli": patch
----
-
-Metadata HMR via SSE — close the agent-edits → preview-refresh loop.
-
-- `@objectstack/metadata`: register `/api/v1/dev/metadata-events` SSE endpoint unconditionally;
-  add `POST` trigger that reloads the artifact and broadcasts a `reload` event to all listeners.
-- `@objectstack/cli` (`os dev`): chokidar-based watch on `objectstack.config.ts` and `src/`;
-  debounced recompile + `POST` to the HMR endpoint so the server reloads without restart.
-- `@objectstack/studio`: `useMetadataHmr` provider opens an `EventSource`, exposes a version
-  counter; previews include it in their query deps, and a top-bar badge surfaces connection
-  state and event counts for diagnostics.
diff --git a/.changeset/occ-if-match.md b/.changeset/occ-if-match.md
deleted file mode 100644
index 6878c747b..000000000
--- a/.changeset/occ-if-match.md
+++ /dev/null
@@ -1,46 +0,0 @@
----
-'@objectstack/spec': minor
-'@objectstack/objectql': minor
-'@objectstack/rest': minor
-'@objectstack/client': minor
----
-
-feat: Optimistic Concurrency Control (OCC) via `If-Match`
-
-Update and Delete requests now accept an optional version token. When supplied,
-the protocol compares it against the record's current `updated_at` (or `version`
-column when available) and rejects with `409 CONCURRENT_UPDATE` on mismatch,
-preventing silent overwrites when two clients edit the same record.
-
-**Wire formats** (opt-in, all server- and client-backward-compatible):
-
-- `PATCH /data/{object}/{id}` — supports `If-Match: "<token>"` header
-  *or* `expectedVersion: "<token>"` body field (body wins when both present).
-- `DELETE /data/{object}/{id}` — supports `If-Match` header *or*
-  `?expectedVersion=...` query param.
-- Conflict response: `409 { error, code: 'CONCURRENT_UPDATE', currentVersion,
-  currentRecord }` so the client can offer Reload / Overwrite / Cancel UX.
-
-**Behaviour**
-
-- Missing/empty version → no check (legacy callers unaffected).
-- Record not found during the version probe → no check; the downstream write
-  produces a normal `404`.
-- Object has no `updated_at` column → no check (explicit opt-out for objects
-  without timestamps).
-- Quoted RFC-7232 tokens (`"…"`) are accepted and unquoted before comparison.
-
-**Client**
-
-`client.data.update(resource, id, data, { ifMatch })` and
-`client.data.delete(resource, id, { ifMatch })` now forward the token as an
-`If-Match` header.
-
-Application-level CAS (findOne + compare in protocol.ts) is used in this slice
-to avoid touching every storage driver. A small TOCTOU window remains; for the
-B2B record-editing latencies this protects against, it is more than sufficient.
-Drivers may later be upgraded to atomic `WHERE id=? AND updated_at=?` writes
-for true CAS without changing the public API.
-
-Tests: 7 new cases in `protocol-data.test.ts` cover opt-in, match, mismatch,
-quote-stripping, no-timestamps, empty-token, and the delete path.
diff --git a/.changeset/slimy-corners-yell.md b/.changeset/slimy-corners-yell.md
deleted file mode 100644
index ed676730d..000000000
--- a/.changeset/slimy-corners-yell.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-"@objectstack/console": minor
----
-
-upgrade objectui
diff --git a/.changeset/solid-rabbits-matter.md b/.changeset/solid-rabbits-matter.md
deleted file mode 100644
index a93a2f8ca..000000000
--- a/.changeset/solid-rabbits-matter.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-"@objectstack/studio": patch
----
-
-fix
diff --git a/.changeset/studio-live-form-preview.md b/.changeset/studio-live-form-preview.md
deleted file mode 100644
index 9171b0ac5..000000000
--- a/.changeset/studio-live-form-preview.md
+++ /dev/null
@@ -1,22 +0,0 @@
----
-'@objectstack/studio': patch
----
-
-Studio: wire form previews to the **real running backend** instead of the
-hand-rolled disabled-input mockup.
-
-- New `LiveFormPreview` component renders `<ObjectForm>` from `@object-ui/plugin-form`
-  against the live `DataSource`, with a Create / Edit / Read-only mode toggle and a
-  record picker (top 10 most-recent records via `dataSource.find`) for Edit mode.
-- New `LivePreviewStatusBar` footer surfaces a pulsing **LIVE** indicator with
-  the backend base URL and bound object so it is obvious previews are real, not
-  mocked.
-- Playground "Form preview" tab now uses `LiveFormPreview` and correctly unwraps
-  the `{ type, items }` envelope returned by `client.meta.getItems('view')`
-  (previously the `.map` call silently threw, leaving the tab showing
-  "No forms yet" even when ten forms existed).
-- `MetadataPreview` routes both single-spec form views and multi-view docs
-  through `LiveFormPreview`; non-form previews now show the LIVE status bar.
-- Object detail page Forms/Views tabs now also detect multi-view documents
-  (where `object` is nested under `list.data.object` / `form.data.object`).
-- Removed legacy mock `FormPreview` component.
diff --git a/.changeset/studio-object-hub-package-id.md b/.changeset/studio-object-hub-package-id.md
deleted file mode 100644
index 066cf4ba0..000000000
--- a/.changeset/studio-object-hub-package-id.md
+++ /dev/null
@@ -1,15 +0,0 @@
----
-'@objectstack/studio': patch
----
-
-Studio: fix Object Hub Views / Forms / Hooks tabs all showing `(0)`.
-
-The `$package.objects.$name` route was passing the **URL slug** (e.g. `crm`)
-as `packageId` to `client.meta.getItems('view', { packageId })`, but the
-metadata server filter requires the **full package id** (e.g.
-`com.example.crm`). The server-side filter never matched, so the tabs
-silently fell back to empty arrays.
-
-Aligned the route with `$package.metadata.$type.$name`: resolve the slug via
-`usePackages(packageId)` and pass `selectedPackage.manifest.id` to the API
-(falling back to the raw slug until the package list loads).
diff --git a/.changeset/view-live-preview.md b/.changeset/view-live-preview.md
deleted file mode 100644
index 9e951cef4..000000000
--- a/.changeset/view-live-preview.md
+++ /dev/null
@@ -1,13 +0,0 @@
----
-"@objectstack/studio": patch
----
-
-Live preview for view/page/dashboard/report metadata.
-
-Adds a built-in `objectstack.view-preview` plugin that registers a
-`Live Preview` viewer (priority 50, beating the default JSON inspector)
-for `view`, `page`, `report`, and `dashboard` types. Opening any of
-these from the Views & Apps list now renders a real `@object-ui`
-preview (grid / kanban / calendar / form / detail) instead of a JSON
-tree. HMR is wired — source edits re-fetch the spec and remount the
-preview without a full page reload.
diff --git a/apps/account/CHANGELOG.md b/apps/account/CHANGELOG.md
index d81c860a7..cf610c64f 100644
--- a/apps/account/CHANGELOG.md
+++ b/apps/account/CHANGELOG.md
@@ -1,5 +1,14 @@
 # @objectstack/account
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/client@4.2.0
+  - @objectstack/client-react@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/apps/account/package.json b/apps/account/package.json
index 8bafdd72f..64b3e743c 100644
--- a/apps/account/package.json
+++ b/apps/account/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/account",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "description": "ObjectStack Account - End-user account & organization self-service portal",
   "license": "Apache-2.0",
   "private": true,
diff --git a/apps/console/CHANGELOG.md b/apps/console/CHANGELOG.md
index 42b61f0d9..c2afd1b2d 100644
--- a/apps/console/CHANGELOG.md
+++ b/apps/console/CHANGELOG.md
@@ -1,3 +1,9 @@
 # @objectstack/console
 
+## 4.2.0
+
+### Minor Changes
+
+- f197c7e: upgrade objectui
+
 ## 4.1.1
diff --git a/apps/console/package.json b/apps/console/package.json
index 04d70b358..fd43b1d95 100644
--- a/apps/console/package.json
+++ b/apps/console/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/console",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "private": true,
   "type": "module",
   "description": "ObjectStack Console - opinionated, fork-ready runtime console built on @object-ui/app-shell with the full plugin set wired up.",
diff --git a/apps/docs/CHANGELOG.md b/apps/docs/CHANGELOG.md
index 9d60f4f4d..b3f0c6229 100644
--- a/apps/docs/CHANGELOG.md
+++ b/apps/docs/CHANGELOG.md
@@ -1,5 +1,7 @@
 # @objectstack/docs
 
+## 4.2.0
+
 ## 4.1.1
 
 ## 4.1.0
diff --git a/apps/docs/package.json b/apps/docs/package.json
index 6a8acd847..3f98a6670 100644
--- a/apps/docs/package.json
+++ b/apps/docs/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/docs",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "private": true,
   "description": "ObjectStack Protocol Documentation Site",
   "license": "Apache-2.0",
diff --git a/apps/studio/CHANGELOG.md b/apps/studio/CHANGELOG.md
index cc77e0e3c..72104a33a 100644
--- a/apps/studio/CHANGELOG.md
+++ b/apps/studio/CHANGELOG.md
@@ -1,5 +1,77 @@
 # @objectstack/studio
 
+## 4.2.0
+
+### Patch Changes
+
+- 3a99239: Metadata HMR via SSE — close the agent-edits → preview-refresh loop.
+
+  - `@objectstack/metadata`: register `/api/v1/dev/metadata-events` SSE endpoint unconditionally;
+    add `POST` trigger that reloads the artifact and broadcasts a `reload` event to all listeners.
+  - `@objectstack/cli` (`os dev`): chokidar-based watch on `objectstack.config.ts` and `src/`;
+    debounced recompile + `POST` to the HMR endpoint so the server reloads without restart.
+  - `@objectstack/studio`: `useMetadataHmr` provider opens an `EventSource`, exposes a version
+    counter; previews include it in their query deps, and a top-bar badge surfaces connection
+    state and event counts for diagnostics.
+
+- bab9bb8: fix
+- 14f5cde: Studio: wire form previews to the **real running backend** instead of the
+  hand-rolled disabled-input mockup.
+
+  - New `LiveFormPreview` component renders `<ObjectForm>` from `@object-ui/plugin-form`
+    against the live `DataSource`, with a Create / Edit / Read-only mode toggle and a
+    record picker (top 10 most-recent records via `dataSource.find`) for Edit mode.
+  - New `LivePreviewStatusBar` footer surfaces a pulsing **LIVE** indicator with
+    the backend base URL and bound object so it is obvious previews are real, not
+    mocked.
+  - Playground "Form preview" tab now uses `LiveFormPreview` and correctly unwraps
+    the `{ type, items }` envelope returned by `client.meta.getItems('view')`
+    (previously the `.map` call silently threw, leaving the tab showing
+    "No forms yet" even when ten forms existed).
+  - `MetadataPreview` routes both single-spec form views and multi-view docs
+    through `LiveFormPreview`; non-form previews now show the LIVE status bar.
+  - Object detail page Forms/Views tabs now also detect multi-view documents
+    (where `object` is nested under `list.data.object` / `form.data.object`).
+  - Removed legacy mock `FormPreview` component.
+
+- f289927: Studio: fix Object Hub Views / Forms / Hooks tabs all showing `(0)`.
+
+  The `$package.objects.$name` route was passing the **URL slug** (e.g. `crm`)
+  as `packageId` to `client.meta.getItems('view', { packageId })`, but the
+  metadata server filter requires the **full package id** (e.g.
+  `com.example.crm`). The server-side filter never matched, so the tabs
+  silently fell back to empty arrays.
+
+  Aligned the route with `$package.metadata.$type.$name`: resolve the slug via
+  `usePackages(packageId)` and pass `selectedPackage.manifest.id` to the API
+  (falling back to the raw slug until the package list loads).
+
+- cefcf64: Live preview for view/page/dashboard/report metadata.
+
+  Adds a built-in `objectstack.view-preview` plugin that registers a
+  `Live Preview` viewer (priority 50, beating the default JSON inspector)
+  for `view`, `page`, `report`, and `dashboard` types. Opening any of
+  these from the Views & Apps list now renders a real `@object-ui`
+  preview (grid / kanban / calendar / form / detail) instead of a JSON
+  tree. HMR is wired — source edits re-fetch the spec and remount the
+  preview without a full page reload.
+
+- Updated dependencies [3a99239]
+- Updated dependencies [2869891]
+  - @objectstack/metadata@4.2.0
+  - @objectstack/spec@4.2.0
+  - @objectstack/objectql@4.2.0
+  - @objectstack/client@4.2.0
+  - @objectstack/runtime@4.2.0
+  - @objectstack/client-react@4.2.0
+  - @objectstack/platform-objects@4.2.0
+  - @objectstack/driver-memory@4.2.0
+  - @objectstack/plugin-msw@4.2.0
+  - @objectstack/service-ai@4.2.0
+  - @objectstack/service-analytics@4.2.0
+  - @objectstack/service-automation@4.2.0
+  - @objectstack/service-feed@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/apps/studio/package.json b/apps/studio/package.json
index e51093977..b8f972263 100644
--- a/apps/studio/package.json
+++ b/apps/studio/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/studio",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "description": "ObjectStack Studio - A metadata-driven admin interface for managing data and configuration",
   "license": "Apache-2.0",
   "type": "module",
diff --git a/examples/app-crm/CHANGELOG.md b/examples/app-crm/CHANGELOG.md
index 2e5fb1c2b..2f208d967 100644
--- a/examples/app-crm/CHANGELOG.md
+++ b/examples/app-crm/CHANGELOG.md
@@ -1,5 +1,16 @@
 # @objectstack/example-crm
 
+## 4.0.8
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/runtime@4.2.0
+  - @objectstack/driver-mongodb@4.2.0
+  - @objectstack/service-analytics@4.2.0
+  - @objectstack/service-automation@4.2.0
+
 ## 4.0.7
 
 ### Patch Changes
diff --git a/examples/app-crm/package.json b/examples/app-crm/package.json
index e978eeab2..8b176aab0 100644
--- a/examples/app-crm/package.json
+++ b/examples/app-crm/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/example-crm",
-  "version": "4.0.7",
+  "version": "4.0.8",
   "description": "Example CRM implementation using ObjectStack Protocol",
   "license": "Apache-2.0",
   "private": true,
diff --git a/examples/app-todo/CHANGELOG.md b/examples/app-todo/CHANGELOG.md
index 3e9e6ad7b..7f014ad92 100644
--- a/examples/app-todo/CHANGELOG.md
+++ b/examples/app-todo/CHANGELOG.md
@@ -1,5 +1,16 @@
 # @objectstack/example-todo
 
+## 4.0.8
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/objectql@4.2.0
+  - @objectstack/client@4.2.0
+  - @objectstack/runtime@4.2.0
+  - @objectstack/driver-memory@4.2.0
+
 ## 4.0.7
 
 ### Patch Changes
diff --git a/examples/app-todo/package.json b/examples/app-todo/package.json
index a24e2ea38..a795d7b56 100644
--- a/examples/app-todo/package.json
+++ b/examples/app-todo/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@example/app-todo",
-  "version": "4.0.7",
+  "version": "4.0.8",
   "description": "Example Todo App using ObjectStack Protocol",
   "license": "Apache-2.0",
   "private": true,
diff --git a/packages/adapters/express/CHANGELOG.md b/packages/adapters/express/CHANGELOG.md
index 85c308eb8..dff46eb38 100644
--- a/packages/adapters/express/CHANGELOG.md
+++ b/packages/adapters/express/CHANGELOG.md
@@ -1,5 +1,7 @@
 # @objectstack/express
 
+## 4.2.0
+
 ## 4.1.1
 
 ## 4.1.0
diff --git a/packages/adapters/express/package.json b/packages/adapters/express/package.json
index 96f2f1b66..94c7a684f 100644
--- a/packages/adapters/express/package.json
+++ b/packages/adapters/express/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/express",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
diff --git a/packages/adapters/fastify/CHANGELOG.md b/packages/adapters/fastify/CHANGELOG.md
index 0c022231c..1d45ddb22 100644
--- a/packages/adapters/fastify/CHANGELOG.md
+++ b/packages/adapters/fastify/CHANGELOG.md
@@ -1,5 +1,7 @@
 # @objectstack/fastify
 
+## 4.2.0
+
 ## 4.1.1
 
 ## 4.1.0
diff --git a/packages/adapters/fastify/package.json b/packages/adapters/fastify/package.json
index e96f01d44..908b4f6ac 100644
--- a/packages/adapters/fastify/package.json
+++ b/packages/adapters/fastify/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/fastify",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
diff --git a/packages/adapters/hono/CHANGELOG.md b/packages/adapters/hono/CHANGELOG.md
index 200f1d271..bf4c40e6d 100644
--- a/packages/adapters/hono/CHANGELOG.md
+++ b/packages/adapters/hono/CHANGELOG.md
@@ -1,5 +1,11 @@
 # @objectstack/hono
 
+## 4.2.0
+
+### Patch Changes
+
+- @objectstack/plugin-hono-server@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/adapters/hono/package.json b/packages/adapters/hono/package.json
index cb9479de8..1b26defd3 100644
--- a/packages/adapters/hono/package.json
+++ b/packages/adapters/hono/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/hono",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
diff --git a/packages/adapters/nestjs/CHANGELOG.md b/packages/adapters/nestjs/CHANGELOG.md
index e816632cf..0789364a2 100644
--- a/packages/adapters/nestjs/CHANGELOG.md
+++ b/packages/adapters/nestjs/CHANGELOG.md
@@ -1,5 +1,7 @@
 # @objectstack/nestjs
 
+## 4.2.0
+
 ## 4.1.1
 
 ## 4.1.0
diff --git a/packages/adapters/nestjs/package.json b/packages/adapters/nestjs/package.json
index 03d5c377a..5d30bafb5 100644
--- a/packages/adapters/nestjs/package.json
+++ b/packages/adapters/nestjs/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/nestjs",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
diff --git a/packages/adapters/nextjs/CHANGELOG.md b/packages/adapters/nextjs/CHANGELOG.md
index 4a3c0a1a2..57584fd4c 100644
--- a/packages/adapters/nextjs/CHANGELOG.md
+++ b/packages/adapters/nextjs/CHANGELOG.md
@@ -1,5 +1,7 @@
 # @objectstack/nextjs
 
+## 4.2.0
+
 ## 4.1.1
 
 ## 4.1.0
diff --git a/packages/adapters/nextjs/package.json b/packages/adapters/nextjs/package.json
index 49ab026cb..967c62b21 100644
--- a/packages/adapters/nextjs/package.json
+++ b/packages/adapters/nextjs/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/nextjs",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
diff --git a/packages/adapters/nuxt/CHANGELOG.md b/packages/adapters/nuxt/CHANGELOG.md
index c27ce0132..4ae3f9ef3 100644
--- a/packages/adapters/nuxt/CHANGELOG.md
+++ b/packages/adapters/nuxt/CHANGELOG.md
@@ -1,5 +1,7 @@
 # @objectstack/nuxt
 
+## 4.2.0
+
 ## 4.1.1
 
 ## 4.1.0
diff --git a/packages/adapters/nuxt/package.json b/packages/adapters/nuxt/package.json
index 4d86c3bf3..d41510060 100644
--- a/packages/adapters/nuxt/package.json
+++ b/packages/adapters/nuxt/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/nuxt",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
diff --git a/packages/adapters/sveltekit/CHANGELOG.md b/packages/adapters/sveltekit/CHANGELOG.md
index 8cfedafaa..2b21c88d3 100644
--- a/packages/adapters/sveltekit/CHANGELOG.md
+++ b/packages/adapters/sveltekit/CHANGELOG.md
@@ -1,5 +1,7 @@
 # @objectstack/sveltekit
 
+## 4.2.0
+
 ## 4.1.1
 
 ## 4.1.0
diff --git a/packages/adapters/sveltekit/package.json b/packages/adapters/sveltekit/package.json
index 69168d11e..f165f91b8 100644
--- a/packages/adapters/sveltekit/package.json
+++ b/packages/adapters/sveltekit/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/sveltekit",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
diff --git a/packages/cli/CHANGELOG.md b/packages/cli/CHANGELOG.md
index 00b9eecfc..30ea5298d 100644
--- a/packages/cli/CHANGELOG.md
+++ b/packages/cli/CHANGELOG.md
@@ -1,5 +1,51 @@
 # @objectstack/cli
 
+## 4.2.0
+
+### Patch Changes
+
+- 3a99239: Metadata HMR via SSE — close the agent-edits → preview-refresh loop.
+
+  - `@objectstack/metadata`: register `/api/v1/dev/metadata-events` SSE endpoint unconditionally;
+    add `POST` trigger that reloads the artifact and broadcasts a `reload` event to all listeners.
+  - `@objectstack/cli` (`os dev`): chokidar-based watch on `objectstack.config.ts` and `src/`;
+    debounced recompile + `POST` to the HMR endpoint so the server reloads without restart.
+  - `@objectstack/studio`: `useMetadataHmr` provider opens an `EventSource`, exposes a version
+    counter; previews include it in their query deps, and a top-bar badge surfaces connection
+    state and event counts for diagnostics.
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/objectql@4.2.0
+  - @objectstack/rest@4.2.0
+  - @objectstack/client@4.2.0
+  - @objectstack/runtime@4.2.0
+  - @objectstack/core@4.2.0
+  - @objectstack/driver-memory@4.2.0
+  - @objectstack/driver-mongodb@4.2.0
+  - @objectstack/driver-sql@4.2.0
+  - @objectstack/driver-turso@4.2.0
+  - @objectstack/plugin-approvals@4.2.0
+  - @objectstack/plugin-audit@4.2.0
+  - @objectstack/plugin-auth@4.2.0
+  - @objectstack/plugin-email@4.2.0
+  - @objectstack/plugin-hono-server@4.2.0
+  - @objectstack/plugin-mcp-server@4.2.0
+  - @objectstack/plugin-reports@4.2.0
+  - @objectstack/plugin-security@4.2.0
+  - @objectstack/plugin-sharing@4.2.0
+  - @objectstack/service-ai@4.2.0
+  - @objectstack/service-analytics@4.2.0
+  - @objectstack/service-automation@4.2.0
+  - @objectstack/service-cache@4.2.0
+  - @objectstack/service-feed@4.2.0
+  - @objectstack/service-job@4.2.0
+  - @objectstack/service-package@4.2.0
+  - @objectstack/service-queue@4.2.0
+  - @objectstack/service-realtime@4.2.0
+  - @objectstack/service-settings@4.2.0
+  - @objectstack/service-storage@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/cli/package.json b/packages/cli/package.json
index 1778aa0d2..b961f6109 100644
--- a/packages/cli/package.json
+++ b/packages/cli/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/cli",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "description": "Command Line Interface for ObjectStack Protocol",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
diff --git a/packages/client-react/CHANGELOG.md b/packages/client-react/CHANGELOG.md
index 485e6b954..8488e191e 100644
--- a/packages/client-react/CHANGELOG.md
+++ b/packages/client-react/CHANGELOG.md
@@ -1,5 +1,14 @@
 # @objectstack/client-react
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/client@4.2.0
+  - @objectstack/core@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/client-react/package.json b/packages/client-react/package.json
index b310ff496..c6f472dc6 100644
--- a/packages/client-react/package.json
+++ b/packages/client-react/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/client-react",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "React hooks for ObjectStack Client SDK",
   "main": "dist/index.js",
diff --git a/packages/client/CHANGELOG.md b/packages/client/CHANGELOG.md
index 11a22fd77..5b35c5ced 100644
--- a/packages/client/CHANGELOG.md
+++ b/packages/client/CHANGELOG.md
@@ -1,5 +1,55 @@
 # @objectstack/client
 
+## 4.2.0
+
+### Minor Changes
+
+- 2869891: feat: Optimistic Concurrency Control (OCC) via `If-Match`
+
+  Update and Delete requests now accept an optional version token. When supplied,
+  the protocol compares it against the record's current `updated_at` (or `version`
+  column when available) and rejects with `409 CONCURRENT_UPDATE` on mismatch,
+  preventing silent overwrites when two clients edit the same record.
+
+  **Wire formats** (opt-in, all server- and client-backward-compatible):
+
+  - `PATCH /data/{object}/{id}` — supports `If-Match: "<token>"` header
+    _or_ `expectedVersion: "<token>"` body field (body wins when both present).
+  - `DELETE /data/{object}/{id}` — supports `If-Match` header _or_
+    `?expectedVersion=...` query param.
+  - Conflict response: `409 { error, code: 'CONCURRENT_UPDATE', currentVersion,
+currentRecord }` so the client can offer Reload / Overwrite / Cancel UX.
+
+  **Behaviour**
+
+  - Missing/empty version → no check (legacy callers unaffected).
+  - Record not found during the version probe → no check; the downstream write
+    produces a normal `404`.
+  - Object has no `updated_at` column → no check (explicit opt-out for objects
+    without timestamps).
+  - Quoted RFC-7232 tokens (`"…"`) are accepted and unquoted before comparison.
+
+  **Client**
+
+  `client.data.update(resource, id, data, { ifMatch })` and
+  `client.data.delete(resource, id, { ifMatch })` now forward the token as an
+  `If-Match` header.
+
+  Application-level CAS (findOne + compare in protocol.ts) is used in this slice
+  to avoid touching every storage driver. A small TOCTOU window remains; for the
+  B2B record-editing latencies this protects against, it is more than sufficient.
+  Drivers may later be upgraded to atomic `WHERE id=? AND updated_at=?` writes
+  for true CAS without changing the public API.
+
+  Tests: 7 new cases in `protocol-data.test.ts` cover opt-in, match, mismatch,
+  quote-stripping, no-timestamps, empty-token, and the delete path.
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/client/package.json b/packages/client/package.json
index a9cc91096..0fdadaf4f 100644
--- a/packages/client/package.json
+++ b/packages/client/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/client",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Official Client SDK for ObjectStack Protocol",
   "main": "dist/index.js",
diff --git a/packages/core/CHANGELOG.md b/packages/core/CHANGELOG.md
index 54c67a26a..63d6d0894 100644
--- a/packages/core/CHANGELOG.md
+++ b/packages/core/CHANGELOG.md
@@ -1,5 +1,12 @@
 # @objectstack/core
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/core/package.json b/packages/core/package.json
index 8bca576ce..97d463675 100644
--- a/packages/core/package.json
+++ b/packages/core/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/core",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Microkernel Core for ObjectStack",
   "type": "module",
diff --git a/packages/create-objectstack/CHANGELOG.md b/packages/create-objectstack/CHANGELOG.md
index a406f8a99..ee9eda892 100644
--- a/packages/create-objectstack/CHANGELOG.md
+++ b/packages/create-objectstack/CHANGELOG.md
@@ -1,5 +1,7 @@
 # create-objectstack
 
+## 4.2.0
+
 ## 4.1.1
 
 ## 4.1.0
diff --git a/packages/create-objectstack/package.json b/packages/create-objectstack/package.json
index 6041d0401..10d6c30f1 100644
--- a/packages/create-objectstack/package.json
+++ b/packages/create-objectstack/package.json
@@ -1,6 +1,6 @@
 {
   "name": "create-objectstack",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "description": "Create a new ObjectStack project — npx create-objectstack",
   "bin": {
     "create-objectstack": "./bin/create-objectstack.js"
diff --git a/packages/formula/CHANGELOG.md b/packages/formula/CHANGELOG.md
index ebee20cba..24fe3b36b 100644
--- a/packages/formula/CHANGELOG.md
+++ b/packages/formula/CHANGELOG.md
@@ -1,5 +1,12 @@
 # @objectstack/formula
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/formula/package.json b/packages/formula/package.json
index e3808f376..5ca14ed97 100644
--- a/packages/formula/package.json
+++ b/packages/formula/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/formula",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "ObjectStack canonical expression engine — CEL (cel-js) + ObjectStack stdlib + dialect registry",
   "main": "dist/index.js",
diff --git a/packages/metadata/CHANGELOG.md b/packages/metadata/CHANGELOG.md
index 01f7d20b3..9e5ab4f23 100644
--- a/packages/metadata/CHANGELOG.md
+++ b/packages/metadata/CHANGELOG.md
@@ -1,5 +1,25 @@
 # @objectstack/metadata
 
+## 4.2.0
+
+### Patch Changes
+
+- 3a99239: Metadata HMR via SSE — close the agent-edits → preview-refresh loop.
+
+  - `@objectstack/metadata`: register `/api/v1/dev/metadata-events` SSE endpoint unconditionally;
+    add `POST` trigger that reloads the artifact and broadcasts a `reload` event to all listeners.
+  - `@objectstack/cli` (`os dev`): chokidar-based watch on `objectstack.config.ts` and `src/`;
+    debounced recompile + `POST` to the HMR endpoint so the server reloads without restart.
+  - `@objectstack/studio`: `useMetadataHmr` provider opens an `EventSource`, exposes a version
+    counter; previews include it in their query deps, and a top-bar badge surfaces connection
+    state and event counts for diagnostics.
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+  - @objectstack/platform-objects@4.2.0
+  - @objectstack/types@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/metadata/package.json b/packages/metadata/package.json
index b96ced76a..0f79fd56a 100644
--- a/packages/metadata/package.json
+++ b/packages/metadata/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/metadata",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Metadata loading, saving, and persistence for ObjectStack",
   "type": "module",
diff --git a/packages/objectql/CHANGELOG.md b/packages/objectql/CHANGELOG.md
index a45ca6b7e..81ec86d9f 100644
--- a/packages/objectql/CHANGELOG.md
+++ b/packages/objectql/CHANGELOG.md
@@ -1,5 +1,57 @@
 # @objectstack/objectql
 
+## 4.2.0
+
+### Minor Changes
+
+- 2869891: feat: Optimistic Concurrency Control (OCC) via `If-Match`
+
+  Update and Delete requests now accept an optional version token. When supplied,
+  the protocol compares it against the record's current `updated_at` (or `version`
+  column when available) and rejects with `409 CONCURRENT_UPDATE` on mismatch,
+  preventing silent overwrites when two clients edit the same record.
+
+  **Wire formats** (opt-in, all server- and client-backward-compatible):
+
+  - `PATCH /data/{object}/{id}` — supports `If-Match: "<token>"` header
+    _or_ `expectedVersion: "<token>"` body field (body wins when both present).
+  - `DELETE /data/{object}/{id}` — supports `If-Match` header _or_
+    `?expectedVersion=...` query param.
+  - Conflict response: `409 { error, code: 'CONCURRENT_UPDATE', currentVersion,
+currentRecord }` so the client can offer Reload / Overwrite / Cancel UX.
+
+  **Behaviour**
+
+  - Missing/empty version → no check (legacy callers unaffected).
+  - Record not found during the version probe → no check; the downstream write
+    produces a normal `404`.
+  - Object has no `updated_at` column → no check (explicit opt-out for objects
+    without timestamps).
+  - Quoted RFC-7232 tokens (`"…"`) are accepted and unquoted before comparison.
+
+  **Client**
+
+  `client.data.update(resource, id, data, { ifMatch })` and
+  `client.data.delete(resource, id, { ifMatch })` now forward the token as an
+  `If-Match` header.
+
+  Application-level CAS (findOne + compare in protocol.ts) is used in this slice
+  to avoid touching every storage driver. A small TOCTOU window remains; for the
+  B2B record-editing latencies this protects against, it is more than sufficient.
+  Drivers may later be upgraded to atomic `WHERE id=? AND updated_at=?` writes
+  for true CAS without changing the public API.
+
+  Tests: 7 new cases in `protocol-data.test.ts` cover opt-in, match, mismatch,
+  quote-stripping, no-timestamps, empty-token, and the delete path.
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+  - @objectstack/formula@4.2.0
+  - @objectstack/types@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/objectql/package.json b/packages/objectql/package.json
index 7db340fa1..f7a472b8b 100644
--- a/packages/objectql/package.json
+++ b/packages/objectql/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/objectql",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Isomorphic ObjectQL Engine for ObjectStack",
   "main": "dist/index.js",
diff --git a/packages/platform-objects/CHANGELOG.md b/packages/platform-objects/CHANGELOG.md
index caea0e0bb..39db9339d 100644
--- a/packages/platform-objects/CHANGELOG.md
+++ b/packages/platform-objects/CHANGELOG.md
@@ -1,5 +1,12 @@
 # @objectstack/platform-objects
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/platform-objects/package.json b/packages/platform-objects/package.json
index fbadd45bb..81235c853 100644
--- a/packages/platform-objects/package.json
+++ b/packages/platform-objects/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/platform-objects",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Core platform object schemas for ObjectStack — identity, security, audit, tenant, and metadata objects",
   "main": "dist/index.js",
diff --git a/packages/plugins/driver-memory/CHANGELOG.md b/packages/plugins/driver-memory/CHANGELOG.md
index 05b6fac64..2eb7ae4dd 100644
--- a/packages/plugins/driver-memory/CHANGELOG.md
+++ b/packages/plugins/driver-memory/CHANGELOG.md
@@ -1,5 +1,13 @@
 # @objectstack/driver-memory
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/plugins/driver-memory/package.json b/packages/plugins/driver-memory/package.json
index bb6f9197b..a5466cb26 100644
--- a/packages/plugins/driver-memory/package.json
+++ b/packages/plugins/driver-memory/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/driver-memory",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "In-Memory Driver for ObjectStack (Reference Implementation)",
   "main": "dist/index.js",
diff --git a/packages/plugins/driver-mongodb/CHANGELOG.md b/packages/plugins/driver-mongodb/CHANGELOG.md
index d0ffb4e51..dadcfff4b 100644
--- a/packages/plugins/driver-mongodb/CHANGELOG.md
+++ b/packages/plugins/driver-mongodb/CHANGELOG.md
@@ -1,5 +1,13 @@
 # @objectstack/driver-mongodb
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/plugins/driver-mongodb/package.json b/packages/plugins/driver-mongodb/package.json
index 81bfb46aa..f916ff59a 100644
--- a/packages/plugins/driver-mongodb/package.json
+++ b/packages/plugins/driver-mongodb/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/driver-mongodb",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "MongoDB Driver for ObjectStack - Native document database driver via official mongodb client",
   "main": "dist/index.js",
diff --git a/packages/plugins/driver-sql/CHANGELOG.md b/packages/plugins/driver-sql/CHANGELOG.md
index d5bf795cc..4da6554e9 100644
--- a/packages/plugins/driver-sql/CHANGELOG.md
+++ b/packages/plugins/driver-sql/CHANGELOG.md
@@ -1,5 +1,13 @@
 # @objectstack/driver-sql
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/plugins/driver-sql/package.json b/packages/plugins/driver-sql/package.json
index 7e52fa75e..94dce8870 100644
--- a/packages/plugins/driver-sql/package.json
+++ b/packages/plugins/driver-sql/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/driver-sql",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "SQL Driver for ObjectStack - Supports PostgreSQL, MySQL, SQLite via Knex",
   "main": "dist/index.js",
diff --git a/packages/plugins/driver-turso/CHANGELOG.md b/packages/plugins/driver-turso/CHANGELOG.md
index a189437c6..923ea1372 100644
--- a/packages/plugins/driver-turso/CHANGELOG.md
+++ b/packages/plugins/driver-turso/CHANGELOG.md
@@ -1,5 +1,14 @@
 # @objectstack/driver-turso
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+  - @objectstack/driver-sql@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/plugins/driver-turso/package.json b/packages/plugins/driver-turso/package.json
index 1ac447f52..8aaf23f22 100644
--- a/packages/plugins/driver-turso/package.json
+++ b/packages/plugins/driver-turso/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/driver-turso",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Turso/libSQL Driver for ObjectStack — Edge-first SQLite with embedded replicas and multi-tenancy",
   "keywords": [
diff --git a/packages/plugins/plugin-approvals/CHANGELOG.md b/packages/plugins/plugin-approvals/CHANGELOG.md
index ce9fbe05d..b38b3af0c 100644
--- a/packages/plugins/plugin-approvals/CHANGELOG.md
+++ b/packages/plugins/plugin-approvals/CHANGELOG.md
@@ -1,5 +1,15 @@
 # @objectstack/plugin-approvals
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+  - @objectstack/formula@4.2.0
+  - @objectstack/platform-objects@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/plugins/plugin-approvals/package.json b/packages/plugins/plugin-approvals/package.json
index e191940ba..0ea3469b5 100644
--- a/packages/plugins/plugin-approvals/package.json
+++ b/packages/plugins/plugin-approvals/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/plugin-approvals",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Multi-step approval engine for ObjectStack — sys_approval_process + sys_approval_request + sys_approval_action + IApprovalService.",
   "main": "dist/index.js",
diff --git a/packages/plugins/plugin-audit/CHANGELOG.md b/packages/plugins/plugin-audit/CHANGELOG.md
index c83536941..93a039f59 100644
--- a/packages/plugins/plugin-audit/CHANGELOG.md
+++ b/packages/plugins/plugin-audit/CHANGELOG.md
@@ -1,5 +1,14 @@
 # @objectstack/plugin-audit
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+  - @objectstack/platform-objects@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/plugins/plugin-audit/package.json b/packages/plugins/plugin-audit/package.json
index 8153328d3..e7f530654 100644
--- a/packages/plugins/plugin-audit/package.json
+++ b/packages/plugins/plugin-audit/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/plugin-audit",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Audit Plugin for ObjectStack — System audit log object and audit trail",
   "main": "dist/index.js",
diff --git a/packages/plugins/plugin-auth/CHANGELOG.md b/packages/plugins/plugin-auth/CHANGELOG.md
index b87b06e45..861ec90d1 100644
--- a/packages/plugins/plugin-auth/CHANGELOG.md
+++ b/packages/plugins/plugin-auth/CHANGELOG.md
@@ -1,5 +1,14 @@
 # Changelog
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+  - @objectstack/platform-objects@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/plugins/plugin-auth/package.json b/packages/plugins/plugin-auth/package.json
index 081dde5fa..1f8c49c92 100644
--- a/packages/plugins/plugin-auth/package.json
+++ b/packages/plugins/plugin-auth/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/plugin-auth",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Authentication & Identity Plugin for ObjectStack",
   "main": "dist/index.js",
diff --git a/packages/plugins/plugin-dev/CHANGELOG.md b/packages/plugins/plugin-dev/CHANGELOG.md
index 385431434..23eb1fc74 100644
--- a/packages/plugins/plugin-dev/CHANGELOG.md
+++ b/packages/plugins/plugin-dev/CHANGELOG.md
@@ -1,5 +1,13 @@
 # @objectstack/plugin-dev
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/plugins/plugin-dev/package.json b/packages/plugins/plugin-dev/package.json
index dfd073fd7..0ae409865 100644
--- a/packages/plugins/plugin-dev/package.json
+++ b/packages/plugins/plugin-dev/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/plugin-dev",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Development Mode Plugin for ObjectStack — auto-enables all services with in-memory implementations",
   "main": "dist/index.js",
diff --git a/packages/plugins/plugin-email/CHANGELOG.md b/packages/plugins/plugin-email/CHANGELOG.md
index b845f341d..9ef2f18b3 100644
--- a/packages/plugins/plugin-email/CHANGELOG.md
+++ b/packages/plugins/plugin-email/CHANGELOG.md
@@ -1,5 +1,14 @@
 # @objectstack/plugin-email
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+  - @objectstack/platform-objects@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/plugins/plugin-email/package.json b/packages/plugins/plugin-email/package.json
index f69684635..3433a2d41 100644
--- a/packages/plugins/plugin-email/package.json
+++ b/packages/plugins/plugin-email/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/plugin-email",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Email service plugin for ObjectStack — IEmailService + transport-pluggable outbound delivery with sys_email persistence.",
   "main": "dist/index.js",
diff --git a/packages/plugins/plugin-hono-server/CHANGELOG.md b/packages/plugins/plugin-hono-server/CHANGELOG.md
index 4b392fd7a..da7988e72 100644
--- a/packages/plugins/plugin-hono-server/CHANGELOG.md
+++ b/packages/plugins/plugin-hono-server/CHANGELOG.md
@@ -1,5 +1,13 @@
 # @objectstack/plugin-hono-server
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/plugins/plugin-hono-server/package.json b/packages/plugins/plugin-hono-server/package.json
index ea6c22ce7..de93ee2f3 100644
--- a/packages/plugins/plugin-hono-server/package.json
+++ b/packages/plugins/plugin-hono-server/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/plugin-hono-server",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Standard Hono Server Adapter for ObjectStack Runtime",
   "main": "dist/index.js",
diff --git a/packages/plugins/plugin-mcp-server/CHANGELOG.md b/packages/plugins/plugin-mcp-server/CHANGELOG.md
index 11d09d671..a84c3c780 100644
--- a/packages/plugins/plugin-mcp-server/CHANGELOG.md
+++ b/packages/plugins/plugin-mcp-server/CHANGELOG.md
@@ -1,5 +1,13 @@
 # @objectstack/plugin-mcp-server
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/plugins/plugin-mcp-server/package.json b/packages/plugins/plugin-mcp-server/package.json
index ece60a258..abc7906de 100644
--- a/packages/plugins/plugin-mcp-server/package.json
+++ b/packages/plugins/plugin-mcp-server/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/plugin-mcp-server",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "MCP Runtime Server Plugin for ObjectStack — exposes AI tools, data resources, and agent prompts via the Model Context Protocol",
   "type": "module",
diff --git a/packages/plugins/plugin-msw/CHANGELOG.md b/packages/plugins/plugin-msw/CHANGELOG.md
index a5c50ea0f..315210f6d 100644
--- a/packages/plugins/plugin-msw/CHANGELOG.md
+++ b/packages/plugins/plugin-msw/CHANGELOG.md
@@ -1,5 +1,15 @@
 # @objectstack/plugin-msw
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/objectql@4.2.0
+  - @objectstack/core@4.2.0
+  - @objectstack/types@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/plugins/plugin-msw/package.json b/packages/plugins/plugin-msw/package.json
index eef072300..c4718284d 100644
--- a/packages/plugins/plugin-msw/package.json
+++ b/packages/plugins/plugin-msw/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/plugin-msw",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "description": "MSW (Mock Service Worker) Plugin for ObjectStack Runtime",
   "license": "Apache-2.0",
   "main": "dist/index.js",
diff --git a/packages/plugins/plugin-reports/CHANGELOG.md b/packages/plugins/plugin-reports/CHANGELOG.md
index a9321360b..bbbb46544 100644
--- a/packages/plugins/plugin-reports/CHANGELOG.md
+++ b/packages/plugins/plugin-reports/CHANGELOG.md
@@ -1,5 +1,14 @@
 # @objectstack/plugin-reports
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+  - @objectstack/platform-objects@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/plugins/plugin-reports/package.json b/packages/plugins/plugin-reports/package.json
index 011e030ce..4183c8f6f 100644
--- a/packages/plugins/plugin-reports/package.json
+++ b/packages/plugins/plugin-reports/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/plugin-reports",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Saved reports + scheduled email digests for ObjectStack — sys_saved_report + sys_report_schedule + IReportService.",
   "main": "dist/index.js",
diff --git a/packages/plugins/plugin-security/CHANGELOG.md b/packages/plugins/plugin-security/CHANGELOG.md
index b07f577c6..79bea3634 100644
--- a/packages/plugins/plugin-security/CHANGELOG.md
+++ b/packages/plugins/plugin-security/CHANGELOG.md
@@ -1,5 +1,14 @@
 # @objectstack/plugin-security
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+  - @objectstack/platform-objects@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/plugins/plugin-security/package.json b/packages/plugins/plugin-security/package.json
index 6804ffca5..c7c742219 100644
--- a/packages/plugins/plugin-security/package.json
+++ b/packages/plugins/plugin-security/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/plugin-security",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Security Plugin for ObjectStack — RBAC, RLS, and Field-Level Security Runtime",
   "main": "dist/index.js",
diff --git a/packages/plugins/plugin-sharing/CHANGELOG.md b/packages/plugins/plugin-sharing/CHANGELOG.md
index e505e319b..0e1199e86 100644
--- a/packages/plugins/plugin-sharing/CHANGELOG.md
+++ b/packages/plugins/plugin-sharing/CHANGELOG.md
@@ -1,5 +1,15 @@
 # @objectstack/plugin-sharing
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/objectql@4.2.0
+  - @objectstack/core@4.2.0
+  - @objectstack/platform-objects@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/plugins/plugin-sharing/package.json b/packages/plugins/plugin-sharing/package.json
index 6b326982c..44c50b499 100644
--- a/packages/plugins/plugin-sharing/package.json
+++ b/packages/plugins/plugin-sharing/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/plugin-sharing",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Record-level sharing for ObjectStack — sys_record_share + middleware that enforces sharingModel + ISharingService.",
   "main": "dist/index.js",
diff --git a/packages/plugins/plugin-webhooks/CHANGELOG.md b/packages/plugins/plugin-webhooks/CHANGELOG.md
index eed8d6ce1..09d4b6491 100644
--- a/packages/plugins/plugin-webhooks/CHANGELOG.md
+++ b/packages/plugins/plugin-webhooks/CHANGELOG.md
@@ -1,5 +1,13 @@
 # @objectstack/plugin-webhooks
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/plugins/plugin-webhooks/package.json b/packages/plugins/plugin-webhooks/package.json
index 0409ae111..0daecd6ea 100644
--- a/packages/plugins/plugin-webhooks/package.json
+++ b/packages/plugins/plugin-webhooks/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/plugin-webhooks",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Outbound webhook delivery plugin for ObjectStack — fan-out data.record.* events to external HTTP(S) sinks with HMAC signing and retry.",
   "main": "dist/index.js",
diff --git a/packages/rest/CHANGELOG.md b/packages/rest/CHANGELOG.md
index 6dea938c0..242018705 100644
--- a/packages/rest/CHANGELOG.md
+++ b/packages/rest/CHANGELOG.md
@@ -1,5 +1,56 @@
 # @objectstack/rest
 
+## 4.2.0
+
+### Minor Changes
+
+- 2869891: feat: Optimistic Concurrency Control (OCC) via `If-Match`
+
+  Update and Delete requests now accept an optional version token. When supplied,
+  the protocol compares it against the record's current `updated_at` (or `version`
+  column when available) and rejects with `409 CONCURRENT_UPDATE` on mismatch,
+  preventing silent overwrites when two clients edit the same record.
+
+  **Wire formats** (opt-in, all server- and client-backward-compatible):
+
+  - `PATCH /data/{object}/{id}` — supports `If-Match: "<token>"` header
+    _or_ `expectedVersion: "<token>"` body field (body wins when both present).
+  - `DELETE /data/{object}/{id}` — supports `If-Match` header _or_
+    `?expectedVersion=...` query param.
+  - Conflict response: `409 { error, code: 'CONCURRENT_UPDATE', currentVersion,
+currentRecord }` so the client can offer Reload / Overwrite / Cancel UX.
+
+  **Behaviour**
+
+  - Missing/empty version → no check (legacy callers unaffected).
+  - Record not found during the version probe → no check; the downstream write
+    produces a normal `404`.
+  - Object has no `updated_at` column → no check (explicit opt-out for objects
+    without timestamps).
+  - Quoted RFC-7232 tokens (`"…"`) are accepted and unquoted before comparison.
+
+  **Client**
+
+  `client.data.update(resource, id, data, { ifMatch })` and
+  `client.data.delete(resource, id, { ifMatch })` now forward the token as an
+  `If-Match` header.
+
+  Application-level CAS (findOne + compare in protocol.ts) is used in this slice
+  to avoid touching every storage driver. A small TOCTOU window remains; for the
+  B2B record-editing latencies this protects against, it is more than sufficient.
+  Drivers may later be upgraded to atomic `WHERE id=? AND updated_at=?` writes
+  for true CAS without changing the public API.
+
+  Tests: 7 new cases in `protocol-data.test.ts` cover opt-in, match, mismatch,
+  quote-stripping, no-timestamps, empty-token, and the delete path.
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+  - @objectstack/service-package@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/rest/package.json b/packages/rest/package.json
index 520dbb191..6732023c3 100644
--- a/packages/rest/package.json
+++ b/packages/rest/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/rest",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "ObjectStack REST API Server - automatic REST endpoint generation from protocol",
   "type": "module",
diff --git a/packages/runtime/CHANGELOG.md b/packages/runtime/CHANGELOG.md
index 84cc3de96..58dc02c2f 100644
--- a/packages/runtime/CHANGELOG.md
+++ b/packages/runtime/CHANGELOG.md
@@ -1,5 +1,19 @@
 # @objectstack/runtime
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/rest@4.2.0
+  - @objectstack/core@4.2.0
+  - @objectstack/formula@4.2.0
+  - @objectstack/plugin-auth@4.2.0
+  - @objectstack/plugin-security@4.2.0
+  - @objectstack/service-i18n@4.2.0
+  - @objectstack/types@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/runtime/package.json b/packages/runtime/package.json
index 07811ab4c..012ec261a 100644
--- a/packages/runtime/package.json
+++ b/packages/runtime/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/runtime",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "ObjectStack Core Runtime & Query Engine",
   "type": "module",
diff --git a/packages/services/service-ai/CHANGELOG.md b/packages/services/service-ai/CHANGELOG.md
index 4a0f58e60..5ae39e06c 100644
--- a/packages/services/service-ai/CHANGELOG.md
+++ b/packages/services/service-ai/CHANGELOG.md
@@ -1,5 +1,13 @@
 # @objectstack/service-ai
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/services/service-ai/package.json b/packages/services/service-ai/package.json
index 8932890d3..25affe37c 100644
--- a/packages/services/service-ai/package.json
+++ b/packages/services/service-ai/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/service-ai",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "AI Service for ObjectStack — implements IAIService with LLM adapter layer, conversation management, tool registry, and REST/SSE routes",
   "type": "module",
diff --git a/packages/services/service-analytics/CHANGELOG.md b/packages/services/service-analytics/CHANGELOG.md
index 4aa1527a9..80cfdf87f 100644
--- a/packages/services/service-analytics/CHANGELOG.md
+++ b/packages/services/service-analytics/CHANGELOG.md
@@ -1,5 +1,13 @@
 # Changelog — @objectstack/service-analytics
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/services/service-analytics/package.json b/packages/services/service-analytics/package.json
index faeb2972d..44463c65c 100644
--- a/packages/services/service-analytics/package.json
+++ b/packages/services/service-analytics/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/service-analytics",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Analytics Service for ObjectStack — implements IAnalyticsService with multi-driver strategy pattern (NativeSQL, ObjectQL, InMemory)",
   "type": "module",
diff --git a/packages/services/service-automation/CHANGELOG.md b/packages/services/service-automation/CHANGELOG.md
index 23cc4d246..ccf680787 100644
--- a/packages/services/service-automation/CHANGELOG.md
+++ b/packages/services/service-automation/CHANGELOG.md
@@ -1,5 +1,14 @@
 # @objectstack/service-automation
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+  - @objectstack/formula@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/services/service-automation/package.json b/packages/services/service-automation/package.json
index f47838038..1b33d6090 100644
--- a/packages/services/service-automation/package.json
+++ b/packages/services/service-automation/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/service-automation",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Automation Service for ObjectStack — implements IAutomationService with plugin-based DAG flow execution engine",
   "type": "module",
diff --git a/packages/services/service-cache/CHANGELOG.md b/packages/services/service-cache/CHANGELOG.md
index f68680fdb..2d1014836 100644
--- a/packages/services/service-cache/CHANGELOG.md
+++ b/packages/services/service-cache/CHANGELOG.md
@@ -1,5 +1,13 @@
 # @objectstack/service-cache
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/services/service-cache/package.json b/packages/services/service-cache/package.json
index db8c6ecef..0f03182bf 100644
--- a/packages/services/service-cache/package.json
+++ b/packages/services/service-cache/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/service-cache",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Cache Service for ObjectStack — implements ICacheService with in-memory and Redis adapters",
   "type": "module",
diff --git a/packages/services/service-feed/CHANGELOG.md b/packages/services/service-feed/CHANGELOG.md
index e6089fa88..cd6bfa14a 100644
--- a/packages/services/service-feed/CHANGELOG.md
+++ b/packages/services/service-feed/CHANGELOG.md
@@ -1,5 +1,13 @@
 # @objectstack/service-feed
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/services/service-feed/package.json b/packages/services/service-feed/package.json
index 906b6aae1..ffbaf0304 100644
--- a/packages/services/service-feed/package.json
+++ b/packages/services/service-feed/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/service-feed",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Feed/Chatter Service for ObjectStack — implements IFeedService with in-memory adapter for comments, reactions, field changes, and record subscriptions",
   "type": "module",
diff --git a/packages/services/service-i18n/CHANGELOG.md b/packages/services/service-i18n/CHANGELOG.md
index 3633f5274..531a86abb 100644
--- a/packages/services/service-i18n/CHANGELOG.md
+++ b/packages/services/service-i18n/CHANGELOG.md
@@ -1,5 +1,13 @@
 # @objectstack/service-i18n
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/services/service-i18n/package.json b/packages/services/service-i18n/package.json
index dc085e30a..95271938b 100644
--- a/packages/services/service-i18n/package.json
+++ b/packages/services/service-i18n/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/service-i18n",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "I18n Service for ObjectStack — implements II18nService with file-based locale loading",
   "type": "module",
diff --git a/packages/services/service-job/CHANGELOG.md b/packages/services/service-job/CHANGELOG.md
index 0936f330b..dc84acaca 100644
--- a/packages/services/service-job/CHANGELOG.md
+++ b/packages/services/service-job/CHANGELOG.md
@@ -1,5 +1,14 @@
 # @objectstack/service-job
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+  - @objectstack/platform-objects@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/services/service-job/package.json b/packages/services/service-job/package.json
index 3da401910..5fc4968d3 100644
--- a/packages/services/service-job/package.json
+++ b/packages/services/service-job/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/service-job",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Job Service for ObjectStack — implements IJobService with setInterval and cron scheduling",
   "type": "module",
diff --git a/packages/services/service-package/CHANGELOG.md b/packages/services/service-package/CHANGELOG.md
index ea7b97303..a60735893 100644
--- a/packages/services/service-package/CHANGELOG.md
+++ b/packages/services/service-package/CHANGELOG.md
@@ -1,5 +1,13 @@
 # @objectstack/service-package
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/services/service-package/package.json b/packages/services/service-package/package.json
index cdf30271f..96542bef9 100644
--- a/packages/services/service-package/package.json
+++ b/packages/services/service-package/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/service-package",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Package management service for ObjectStack — publish, install, and manage packages",
   "type": "module",
diff --git a/packages/services/service-queue/CHANGELOG.md b/packages/services/service-queue/CHANGELOG.md
index 7a6c73fc3..e3306ee3d 100644
--- a/packages/services/service-queue/CHANGELOG.md
+++ b/packages/services/service-queue/CHANGELOG.md
@@ -1,5 +1,14 @@
 # @objectstack/service-queue
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+  - @objectstack/platform-objects@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/services/service-queue/package.json b/packages/services/service-queue/package.json
index 99bd52183..027714c70 100644
--- a/packages/services/service-queue/package.json
+++ b/packages/services/service-queue/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/service-queue",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Queue Service for ObjectStack — implements IQueueService with in-memory and BullMQ adapters",
   "type": "module",
diff --git a/packages/services/service-realtime/CHANGELOG.md b/packages/services/service-realtime/CHANGELOG.md
index 91ec29ef3..c2dd7c989 100644
--- a/packages/services/service-realtime/CHANGELOG.md
+++ b/packages/services/service-realtime/CHANGELOG.md
@@ -1,5 +1,14 @@
 # @objectstack/service-realtime
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+  - @objectstack/platform-objects@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/services/service-realtime/package.json b/packages/services/service-realtime/package.json
index a82204a34..ad6e03033 100644
--- a/packages/services/service-realtime/package.json
+++ b/packages/services/service-realtime/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/service-realtime",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Realtime Service for ObjectStack — implements IRealtimeService with WebSocket and in-memory pub/sub",
   "type": "module",
diff --git a/packages/services/service-settings/CHANGELOG.md b/packages/services/service-settings/CHANGELOG.md
index 1e0f68fee..2e9b47388 100644
--- a/packages/services/service-settings/CHANGELOG.md
+++ b/packages/services/service-settings/CHANGELOG.md
@@ -1,5 +1,14 @@
 # @objectstack/service-settings
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+  - @objectstack/platform-objects@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/services/service-settings/package.json b/packages/services/service-settings/package.json
index 7e1d441ff..14c7cbe45 100644
--- a/packages/services/service-settings/package.json
+++ b/packages/services/service-settings/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/service-settings",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Settings service for ObjectStack — manifest registry + K/V resolver (Env > Tenant > User > Default) + REST routes. See ADR-0007.",
   "type": "module",
diff --git a/packages/services/service-storage/CHANGELOG.md b/packages/services/service-storage/CHANGELOG.md
index 7c96441fb..3d0dd5a8c 100644
--- a/packages/services/service-storage/CHANGELOG.md
+++ b/packages/services/service-storage/CHANGELOG.md
@@ -1,5 +1,13 @@
 # @objectstack/service-storage
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+  - @objectstack/core@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/services/service-storage/package.json b/packages/services/service-storage/package.json
index 1babd75d2..b6f433f28 100644
--- a/packages/services/service-storage/package.json
+++ b/packages/services/service-storage/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/service-storage",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Storage Service for ObjectStack — implements IStorageService with local filesystem and S3 adapter skeleton",
   "type": "module",
diff --git a/packages/spec/CHANGELOG.md b/packages/spec/CHANGELOG.md
index 0e831b2ed..ff02e2841 100644
--- a/packages/spec/CHANGELOG.md
+++ b/packages/spec/CHANGELOG.md
@@ -1,5 +1,49 @@
 # @objectstack/spec
 
+## 4.2.0
+
+### Minor Changes
+
+- 2869891: feat: Optimistic Concurrency Control (OCC) via `If-Match`
+
+  Update and Delete requests now accept an optional version token. When supplied,
+  the protocol compares it against the record's current `updated_at` (or `version`
+  column when available) and rejects with `409 CONCURRENT_UPDATE` on mismatch,
+  preventing silent overwrites when two clients edit the same record.
+
+  **Wire formats** (opt-in, all server- and client-backward-compatible):
+
+  - `PATCH /data/{object}/{id}` — supports `If-Match: "<token>"` header
+    _or_ `expectedVersion: "<token>"` body field (body wins when both present).
+  - `DELETE /data/{object}/{id}` — supports `If-Match` header _or_
+    `?expectedVersion=...` query param.
+  - Conflict response: `409 { error, code: 'CONCURRENT_UPDATE', currentVersion,
+currentRecord }` so the client can offer Reload / Overwrite / Cancel UX.
+
+  **Behaviour**
+
+  - Missing/empty version → no check (legacy callers unaffected).
+  - Record not found during the version probe → no check; the downstream write
+    produces a normal `404`.
+  - Object has no `updated_at` column → no check (explicit opt-out for objects
+    without timestamps).
+  - Quoted RFC-7232 tokens (`"…"`) are accepted and unquoted before comparison.
+
+  **Client**
+
+  `client.data.update(resource, id, data, { ifMatch })` and
+  `client.data.delete(resource, id, { ifMatch })` now forward the token as an
+  `If-Match` header.
+
+  Application-level CAS (findOne + compare in protocol.ts) is used in this slice
+  to avoid touching every storage driver. A small TOCTOU window remains; for the
+  B2B record-editing latencies this protects against, it is more than sufficient.
+  Drivers may later be upgraded to atomic `WHERE id=? AND updated_at=?` writes
+  for true CAS without changing the public API.
+
+  Tests: 7 new cases in `protocol-data.test.ts` cover opt-in, match, mismatch,
+  quote-stripping, no-timestamps, empty-token, and the delete path.
+
 ## 4.1.1
 
 ## 4.1.0
diff --git a/packages/spec/package.json b/packages/spec/package.json
index 812a61fb6..31a32fe93 100644
--- a/packages/spec/package.json
+++ b/packages/spec/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/spec",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "description": "ObjectStack Protocol & Specification - TypeScript Interfaces, JSON Schemas, and Convention Configurations",
   "license": "Apache-2.0",
   "main": "dist/index.js",
diff --git a/packages/types/CHANGELOG.md b/packages/types/CHANGELOG.md
index 057db1a1c..5a50f7af9 100644
--- a/packages/types/CHANGELOG.md
+++ b/packages/types/CHANGELOG.md
@@ -1,5 +1,12 @@
 # @objectstack/types
 
+## 4.2.0
+
+### Patch Changes
+
+- Updated dependencies [2869891]
+  - @objectstack/spec@4.2.0
+
 ## 4.1.1
 
 ### Patch Changes
diff --git a/packages/types/package.json b/packages/types/package.json
index e027dc0e1..fb9594a8d 100644
--- a/packages/types/package.json
+++ b/packages/types/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@objectstack/types",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "license": "Apache-2.0",
   "description": "Shared interfaces describing the ObjectStack Runtime environment",
   "main": "dist/index.js",
diff --git a/packages/vscode-objectstack/CHANGELOG.md b/packages/vscode-objectstack/CHANGELOG.md
index bde68f661..94cb99da0 100644
--- a/packages/vscode-objectstack/CHANGELOG.md
+++ b/packages/vscode-objectstack/CHANGELOG.md
@@ -1,5 +1,7 @@
 # objectstack-vscode
 
+## 4.2.0
+
 ## 4.1.1
 
 ## 4.1.0
diff --git a/packages/vscode-objectstack/package.json b/packages/vscode-objectstack/package.json
index 9f3122adb..638d54101 100644
--- a/packages/vscode-objectstack/package.json
+++ b/packages/vscode-objectstack/package.json
@@ -2,7 +2,7 @@
   "name": "objectstack-vscode",
   "displayName": "ObjectStack",
   "description": "ObjectStack Protocol — Autocomplete, validation, and inline diagnostics for .object.ts, .view.ts, and objectstack.config.ts files",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "publisher": "objectstack",
   "license": "Apache-2.0",
   "repository": {