diff --git a/.github/workflows/internal-image.yml b/.github/workflows/internal-image.yml
new file mode 100644
index 0000000000..5b3d507cdd
--- /dev/null
+++ b/.github/workflows/internal-image.yml
@@ -0,0 +1,73 @@
+name: Internal Image
+
+on:
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.sha }}
+  cancel-in-progress: false
+
+permissions:
+  contents: read
+  packages: write
+
+jobs:
+  publish:
+    name: Build and publish CHEK image
+    runs-on: ubuntu-24.04
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1
+        with:
+          persist-credentials: false
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@96fe6ef7f33517b61c61be40b68a1882f3264fb8
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@bb05f3f5519dd87d3ba754cc423b652a5edd6d2c
+
+      - name: Log in to GHCR
+        uses: docker/login-action@dbcb813823bdd20940b903addbd779551569679f
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Refuse to overwrite immutable tag
+        env:
+          IMAGE_REF: ghcr.io/${{ github.repository }}:sha-${{ github.sha }}
+        run: |
+          if docker buildx imagetools inspect "${IMAGE_REF}" >/dev/null 2>inspect-error.log; then
+            echo "::error::Immutable image tag already exists: ${IMAGE_REF}"
+            exit 1
+          fi
+          if ! grep -Eiq 'manifest unknown|name unknown|not found' inspect-error.log; then
+            cat inspect-error.log >&2
+            echo "::error::Unable to prove immutable image tag is absent"
+            exit 1
+          fi
+
+      - name: Extract image metadata
+        id: meta
+        uses: docker/metadata-action@dc802804100637a589fabce1cb79ff13a1411302
+        with:
+          images: ghcr.io/${{ github.repository }}
+          tags: |
+            type=sha,prefix=sha-,format=long
+
+      - name: Build and push image
+        uses: docker/build-push-action@53b7df96c91f9c12dcc8a07bcb9ccacbed38856a
+        with:
+          context: .
+          file: Dockerfile
+          push: true
+          platforms: linux/amd64,linux/arm64
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha,scope=codex-lb-internal
+          cache-to: type=gha,mode=max,scope=codex-lb-internal
diff --git a/openspec/changes/publish-chek-internal-images/.openspec.yaml b/openspec/changes/publish-chek-internal-images/.openspec.yaml
new file mode 100644
index 0000000000..5081c98763
--- /dev/null
+++ b/openspec/changes/publish-chek-internal-images/.openspec.yaml
@@ -0,0 +1,2 @@
+schema: spec-driven
+created: 2026-08-12
diff --git a/openspec/changes/publish-chek-internal-images/proposal.md b/openspec/changes/publish-chek-internal-images/proposal.md
new file mode 100644
index 0000000000..aa4729c0b3
--- /dev/null
+++ b/openspec/changes/publish-chek-internal-images/proposal.md
@@ -0,0 +1,27 @@
+# Change: publish-chek-internal-images
+
+## Why
+
+CHEK deploys its maintained `chekdata/codex-lb` fork through ArgoCD. Production
+must consume an image built from the reviewed fork commit rather than an
+upstream image or a mutable local build, but the fork currently has no
+repository-owned image publisher.
+
+## What Changes
+
+- Add a focused GitHub Actions workflow that publishes the fork to
+  `ghcr.io/chekdata/codex-lb` after a push to `main` or an explicit manual run.
+- Publish both supported Linux architectures in one manifest.
+- Publish an immutable full-SHA tag for GitOps while granting the workflow only
+  read-content and write-package access; do not publish a mutable `main` tag.
+- Fail closed before building when the full-SHA tag already exists or the
+  registry cannot prove that it is absent.
+- Serialize all runs for the same commit across branch and tag aliases so the
+  absence check and first publication cannot race.
+
+## Impact
+
+- Affected capability: `github-automation`
+- Affected automation: `.github/workflows/internal-image.yml`
+- Production manifests can pin a reviewed `sha-*` image without depending on
+  upstream publishing permissions or abbreviated-tag collisions.
diff --git a/openspec/changes/publish-chek-internal-images/specs/github-automation/spec.md b/openspec/changes/publish-chek-internal-images/specs/github-automation/spec.md
new file mode 100644
index 0000000000..2a9d0d3541
--- /dev/null
+++ b/openspec/changes/publish-chek-internal-images/specs/github-automation/spec.md
@@ -0,0 +1,62 @@
+## ADDED Requirements
+
+### Requirement: CHEK fork publishes internally owned container images
+
+The `chekdata/codex-lb` repository SHALL build and publish a container image to
+`ghcr.io/chekdata/codex-lb` after changes land on `main` and when an operator
+explicitly dispatches the workflow. The published manifest MUST support
+`linux/amd64` and `linux/arm64`, MUST include an immutable `sha-<full-commit>`
+tag, and MUST NOT publish a mutable `main` tag. Production GitOps consumers
+MUST be able to select the immutable tag.
+
+Before publishing, the workflow MUST prove that the full-SHA tag does not
+already exist. It MUST fail without building when the tag exists and MUST fail
+closed when a registry or network error prevents that absence check. It MUST
+NOT overwrite a previously published full-SHA tag. Runs selecting the same
+commit through different branch or tag refs MUST be serialized by the full
+commit SHA and MUST NOT cancel the run that currently owns publication.
+
+The workflow MUST use pinned action revisions and MUST limit its repository
+permissions to reading contents and writing packages. Pull request events MUST
+NOT publish images.
+
+#### Scenario: Main commit produces an immutable multi-architecture image
+
+- **WHEN** a reviewed commit lands on `main`
+- **THEN** the workflow publishes `ghcr.io/chekdata/codex-lb:sha-<full-commit>`
+- **AND** the image manifest supports `linux/amd64` and `linux/arm64`
+- **AND** the run does not publish a mutable `main` tag
+
+#### Scenario: Pull request validation cannot publish a package
+
+- **WHEN** a pull request is opened or updated
+- **THEN** the internal image workflow does not run from that event
+- **AND** no image tag is published by the pull request
+
+#### Scenario: Operator can rebuild the current selected revision
+
+- **WHEN** an operator manually dispatches the workflow on an allowed ref
+- **AND** the selected commit's full-SHA tag does not yet exist
+- **THEN** the workflow builds and publishes the selected commit with its
+  immutable full-SHA tag
+
+#### Scenario: Repeated publication cannot change an immutable tag
+
+- **GIVEN** the selected commit's full-SHA tag already exists in GHCR
+- **WHEN** the workflow is rerun or manually dispatched for that commit
+- **THEN** it fails before the image build
+- **AND** the existing tag is not overwritten
+
+#### Scenario: Registry uncertainty fails closed
+
+- **GIVEN** the workflow cannot determine whether the full-SHA tag exists
+- **WHEN** the pre-publish check encounters a registry or network error
+- **THEN** the workflow fails without publishing
+
+#### Scenario: Branch and tag aliases cannot race publication
+
+- **GIVEN** a branch and a tag both select the same commit
+- **WHEN** push and manual-dispatch runs overlap for those refs
+- **THEN** the runs execute the absence check and publication serially
+- **AND** the later run observes the tag created by the first run and fails
+  before building
diff --git a/openspec/changes/publish-chek-internal-images/tasks.md b/openspec/changes/publish-chek-internal-images/tasks.md
new file mode 100644
index 0000000000..2cdbc3c5b0
--- /dev/null
+++ b/openspec/changes/publish-chek-internal-images/tasks.md
@@ -0,0 +1,16 @@
+# Tasks: publish-chek-internal-images
+
+## 1. Internal image publisher
+
+- [x] 1.1 Add a main-branch and manual-dispatch GHCR workflow with pinned actions
+- [x] 1.2 Build and publish a multi-architecture image for amd64 and arm64
+- [x] 1.3 Emit only an immutable full-SHA tag with minimal permissions
+- [x] 1.4 Refuse to overwrite an existing full-SHA tag and fail closed when its
+      registry state cannot be confirmed
+- [x] 1.5 Serialize publication by full commit SHA across branch and tag refs
+
+## 2. Verification
+
+- [x] 2.1 Validate the workflow YAML and repository action policy
+- [x] 2.2 Run strict OpenSpec validation
+- [ ] 2.3 Merge the focused PR and verify the first main-branch image manifest