diff --git a/.github/workflows/package.yml b/.github/workflows/package.yml
index 926fcbb..85c36e2 100644
--- a/.github/workflows/package.yml
+++ b/.github/workflows/package.yml
@@ -325,18 +325,18 @@ jobs:
           name: base-cli-release-metadata-${{ github.run_id }}
           path: dist
 
-      - name: Create or update GitHub Release
+      - name: Create GitHub Release
         env:
           GH_TOKEN: ${{ github.token }}
         run: |
           tag="$GITHUB_REF_NAME"
           assets=(dist/*.whl dist/*.tar.gz dist/SHA256SUMS dist/SBOM.spdx.json dist/RELEASE-BOM-ROW.json)
           if gh release view "$tag" --repo "$GITHUB_REPOSITORY" >/dev/null 2>&1; then
-            gh release upload "$tag" "${assets[@]}" --clobber --repo "$GITHUB_REPOSITORY"
-          else
-            gh release create "$tag" "${assets[@]}" \
-              --repo "$GITHUB_REPOSITORY" \
-              --title "$tag" \
-              --generate-notes \
-              --notes "Published distributions and release metadata for $tag. See CHANGELOG.md for the reviewed release notes."
+            echo "Published release $tag already exists; refusing to replace immutable release assets." >&2
+            exit 1
           fi
+          gh release create "$tag" "${assets[@]}" \
+            --repo "$GITHUB_REPOSITORY" \
+            --title "$tag" \
+            --generate-notes \
+            --notes "Published distributions and release metadata for $tag. See CHANGELOG.md for the reviewed release notes."
diff --git a/README.md b/README.md
index 0d0ae5a..23dc8dd 100644
--- a/README.md
+++ b/README.md
@@ -33,6 +33,8 @@ Compatibility results and the permissioned-adopter policy are documented in
 the [adoption and compatibility evidence guide](https://basefoundry.github.io/base-cli/adoption-evidence/).
 The [compatibility dashboard](https://basefoundry.github.io/base-cli/compatibility-dashboard/)
 shows the declared and CI-tested dependency and platform support boundaries.
+The shared Base ecosystem boundary is maintained in the [Base ecosystem
+platform, license, and release policy](https://github.com/basefoundry/base/blob/main/docs/ecosystem-policy.md).
 
 ## Quick start
 
@@ -67,8 +69,10 @@ Release builds, TestPyPI rehearsals, and protected PyPI publication are
 documented in [`docs/releasing.md`](https://basefoundry.github.io/base-cli/releasing/). The package exposes
 `base_cli.__version__`, which matches the distribution version.
 
-The package is distributed under the Apache License 2.0. Base itself remains
-licensed separately under AGPL-3.0-or-later.
+The package is distributed under the Apache License 2.0. Base is licensed under
+Apache-2.0 starting with v1.9.0; earlier Base releases retain the license stated
+in their release documentation. The two projects remain independently licensed
+and independently released.
 
 `base_cli` is designed to be embedded by applications rather than to define
 an application's project model. Base is one consumer of the library, not part
diff --git a/docs/platform-support.md b/docs/platform-support.md
index ce0824e..89a314d 100644
--- a/docs/platform-support.md
+++ b/docs/platform-support.md
@@ -19,6 +19,11 @@ Native Windows support applies to the generic Python package. It does not make
 Base or `basectl` natively Windows-compatible; those consumers have their own
 Unix-tooling and shell boundaries. The package does not provide package-manager
 integration, shell startup management, or WSL/Windows path translation.
+The coordinated Base release matrix is intentionally narrower: Base records
+Ubuntu 24.04 and macOS 14 combinations in its release BOM. See the [Base
+ecosystem platform, license, and release
+policy](https://github.com/basefoundry/base/blob/main/docs/ecosystem-policy.md)
+for the cross-repository boundary.
 
 Recursive invocation-temp content erasure requires descriptor-relative,
 no-follow directory operations. Linux, macOS, and WSL2 provide those
diff --git a/docs/releasing.md b/docs/releasing.md
index b3c2766..99f8c94 100644
--- a/docs/releasing.md
+++ b/docs/releasing.md
@@ -4,6 +4,11 @@ The `base-cli` distribution is built and published from the standalone
 `basefoundry/base-cli` repository. The package name on PyPI is `base-cli`; the
 Python import name is `base_cli`.
 
+`base-cli` releases are independent of Base releases. The shared provider,
+platform, license, and release-artifact rules are summarized in the [Base
+ecosystem platform, license, and release
+policy](https://github.com/basefoundry/base/blob/main/docs/ecosystem-policy.md).
+
 ## Version and tag contract
 
 `VERSION` is the release version source of truth. The build backend reads it for
@@ -44,8 +49,9 @@ the exact reviewed wheel, sdist, `SHA256SUMS`, `SBOM.spdx.json`, and
 `RELEASE-BOM-ROW.json` downloaded from the build job. GitHub-generated
 comparison notes are supplemented by the
 dated section in `CHANGELOG.md`; the tagged release is rejected when `VERSION`
-or that section does not match the tag. Rerunning a tag updates an existing
-release's assets with `--clobber` instead of creating a second release.
+or that section does not match the tag. Published tags and release assets are
+immutable. A rerun that finds an existing GitHub Release fails closed;
+corrections require a new patch version.
 
 ## Independent verification
 
diff --git a/tests/test_package_workflow.py b/tests/test_package_workflow.py
index 1ffb200..47fc459 100644
--- a/tests/test_package_workflow.py
+++ b/tests/test_package_workflow.py
@@ -8,3 +8,11 @@ def test_package_workflow_uses_numeric_reproducibility_epoch() -> None:
 
     assert "github.event.head_commit.timestamp" not in workflow
     assert workflow.count("SOURCE_DATE_EPOCH: '0'") == 2
+
+
+def test_package_workflow_does_not_replace_published_release_assets() -> None:
+    workflow = (Path(__file__).resolve().parents[1] / ".github/workflows/package.yml").read_text(encoding="utf-8")
+
+    assert "Create GitHub Release" in workflow
+    assert "refusing to replace immutable release assets" in workflow
+    assert "--clobber" not in workflow