diff --git a/.github/workflows/purview-release.yml b/.github/workflows/purview-release.yml
index bb44b35..d11878b 100644
--- a/.github/workflows/purview-release.yml
+++ b/.github/workflows/purview-release.yml
@@ -21,7 +21,8 @@ on:
         type: string
       release-branch:
         description: >-
-          Branch that triggers this release (main or release). Used only for the concurrency group.
+          Branch that triggers this release (main or release). Retained for backward compatibility;
+          callers now control release serialization via their own concurrency group.
         required: false
         default: main
         type: string
@@ -67,10 +68,6 @@ permissions:
   contents: write
   packages: read
 
-concurrency:
-  group: purview-release-${{ inputs.release-branch }}
-  cancel-in-progress: false
-
 jobs:
   release:
     name: Release
diff --git a/README.md b/README.md
index 2e21520..bc89469 100644
--- a/README.md
+++ b/README.md
@@ -45,6 +45,10 @@ name: Release
 on:
   push:
     branches: [main]
+concurrency:
+  # Serialize releases; callers own concurrency (see docs/releasing.md).
+  group: release-${{ github.ref }}
+  cancel-in-progress: false
 jobs:
   release:
     uses: purview-dev/build/.github/workflows/purview-release.yml@main
diff --git a/docs/releasing.md b/docs/releasing.md
index efe03b5..907b895 100644
--- a/docs/releasing.md
+++ b/docs/releasing.md
@@ -19,6 +19,16 @@ Each repository is gated by a pull-request build. Two release trigger models are
 
 In both models the reusable `purview-release.yml` workflow reads `package.json`'s `version`, skips when the `v{version}` tag already exists, and otherwise runs the pipeline with `Release__Mode` set. Because publication is idempotent (`--skip-duplicate`) and the tag is created by the workflow, re-merging `main` into `release` after a failed release is safe.
 
+The reusable workflow does **not** define a concurrency group. GitHub Actions cancels a run as a deadlock when a caller workflow and the reusable workflow it calls share the same concurrency group (the caller's `purview-release-main` collided with the reusable workflow's `purview-release-${{ inputs.release-branch }}` resolving to the same value, producing *"Canceling since a deadlock was detected for concurrency group"*). Callers must own release serialization by defining their own `concurrency` block:
+
+```yaml
+concurrency:
+  group: release-${{ github.ref }}
+  cancel-in-progress: false
+```
+
+The `release-branch` input is retained for backward compatibility only.
+
 ## This repository's CI/CD
 
 This repository dogfoods the shared tool. CI performs locked restore, warnings-as-errors compilation, packing, installation from the generated package, then runs `purview-build` against this repository so the project builds and packs itself.