diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 6732cf13..81a1196e 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -68,19 +68,60 @@ jobs:
       - name: Install Python dependencies
         run: uv sync --all-packages
 
+      - name: Prepare next prerelease branch
+        if: ${{ inputs.release_kind == 'rc' }}
+        run: |
+          set -euo pipefail
+
+          source_sha="$(git rev-parse HEAD)"
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+
+          if git ls-remote --exit-code --heads origin "${KTX_PRERELEASE_BRANCH}" >/dev/null 2>&1; then
+            git fetch origin "${KTX_PRERELEASE_BRANCH}"
+            git checkout -B "${KTX_PRERELEASE_BRANCH}" "origin/${KTX_PRERELEASE_BRANCH}"
+            git merge --no-edit "${source_sha}"
+          else
+            git checkout -B "${KTX_PRERELEASE_BRANCH}" "${source_sha}"
+          fi
+
+          git push --set-upstream origin "HEAD:${KTX_PRERELEASE_BRANCH}"
+        env:
+          KTX_PRERELEASE_BRANCH: next
+
       - name: Dry-run semantic release
         if: ${{ !inputs.publish_live }}
-        run: pnpm run semantic-release:dry-run
+        run: |
+          set -euo pipefail
+
+          if [ "${KTX_RELEASE_KIND}" = "rc" ]; then
+            export GITHUB_REF="refs/heads/${KTX_PRERELEASE_BRANCH}"
+            export GITHUB_REF_NAME="${KTX_PRERELEASE_BRANCH}"
+            export GITHUB_SHA="$(git rev-parse HEAD)"
+          fi
+
+          pnpm run semantic-release:dry-run
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           KTX_RELEASE_KIND: ${{ inputs.release_kind }}
+          KTX_PRERELEASE_BRANCH: next
           FORCE_RELEASE: ${{ inputs.force_release }}
 
       - name: Create semantic release
         if: ${{ inputs.publish_live }}
-        run: pnpm run semantic-release
+        run: |
+          set -euo pipefail
+
+          if [ "${KTX_RELEASE_KIND}" = "rc" ]; then
+            export GITHUB_REF="refs/heads/${KTX_PRERELEASE_BRANCH}"
+            export GITHUB_REF_NAME="${KTX_PRERELEASE_BRANCH}"
+            export GITHUB_SHA="$(git rev-parse HEAD)"
+          fi
+
+          pnpm run semantic-release
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           KTX_RELEASE_KIND: ${{ inputs.release_kind }}
+          KTX_PRERELEASE_BRANCH: next
           FORCE_RELEASE: ${{ inputs.force_release }}
           NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}
diff --git a/docs/release.md b/docs/release.md
index 670a6a70..075e2845 100644
--- a/docs/release.md
+++ b/docs/release.md
@@ -12,6 +12,11 @@ KTX has two npm release channels:
 - `rc` publishes prereleases such as `0.1.0-rc.2` to the npm `next` tag.
 - `stable` publishes normal releases such as `0.1.0` to the npm `latest` tag.
 
+Run rc releases from the source branch you want to publish. The workflow
+creates or updates the `next` prerelease branch from that source branch before
+running semantic-release, because semantic-release requires a dedicated
+prerelease branch in addition to the stable `main` branch.
+
 Run stable releases only from `main`. The workflow rejects stable releases from
 other branches.
 
@@ -43,8 +48,9 @@ publishing to npm.
    if semantic-release doesn't find a releasable commit.
 7. Run the workflow.
 
-The dry-run uses the same semantic-release configuration as a live release. It
-doesn't publish to npm and doesn't commit release files.
+The dry-run uses the same semantic-release configuration as a live release. For
+rc releases, it can create or update the `next` branch. It doesn't publish to
+npm and doesn't commit release files.
 
 ## Publish an rc release
 
@@ -53,15 +59,16 @@ promoting to `latest`.
 
 1. Open **Actions** in GitHub.
 2. Select **KTX Release**.
-3. Select the branch to release from.
+3. Select the source branch to release from.
 4. Set **release_kind** to `rc`.
 5. Set **publish_live** to `true`.
 6. Optional: Set **force_release** to `true`.
 7. Run the workflow.
 
-The workflow publishes `@kaelio/ktx` with `--access public --tag next`, runs the
-published package smoke test, creates a GitHub release, and commits
-`CHANGELOG.md`, `package.json`, and `release-policy.json`.
+The workflow merges the selected source branch into `next`, publishes
+`@kaelio/ktx` with `--access public --tag next`, runs the published package
+smoke test, creates a GitHub release, and commits `CHANGELOG.md`,
+`package.json`, and `release-policy.json` on `next`.
 
 ## Publish a stable release
 
diff --git a/scripts/release-workflow.test.mjs b/scripts/release-workflow.test.mjs
index 8e8d6df0..d2936207 100644
--- a/scripts/release-workflow.test.mjs
+++ b/scripts/release-workflow.test.mjs
@@ -16,9 +16,13 @@ describe('release workflow', () => {
     assert.match(workflow, /^  contents: write$/m);
     assert.match(workflow, /fetch-depth: 0/);
     assert.match(workflow, /registry-url: "https:\/\/registry\.npmjs\.org"/);
+    assert.match(workflow, /Prepare next prerelease branch/);
+    assert.match(workflow, /git checkout -B "\$\{KTX_PRERELEASE_BRANCH\}"/);
+    assert.match(workflow, /GITHUB_REF="refs\/heads\/\$\{KTX_PRERELEASE_BRANCH\}"/);
     assert.match(workflow, /pnpm run semantic-release:dry-run/);
     assert.match(workflow, /pnpm run semantic-release$/m);
     assert.match(workflow, /KTX_RELEASE_KIND: \$\{\{ inputs.release_kind \}\}/);
+    assert.match(workflow, /KTX_PRERELEASE_BRANCH: next/);
     assert.match(workflow, /FORCE_RELEASE: \$\{\{ inputs.force_release \}\}/);
     assert.match(workflow, /NODE_AUTH_TOKEN: \$\{\{ secrets.NPM_TOKEN \}\}/);
     assert.doesNotMatch(workflow, /^  push:/m);
diff --git a/scripts/semantic-release-config.cjs b/scripts/semantic-release-config.cjs
index 85df2620..66b9aad7 100644
--- a/scripts/semantic-release-config.cjs
+++ b/scripts/semantic-release-config.cjs
@@ -82,6 +82,10 @@ function releaseKind(env) {
   return env.KTX_RELEASE_KIND || env.INPUT_RELEASE_KIND || 'rc';
 }
 
+function prereleaseBranch(env) {
+  return env.KTX_PRERELEASE_BRANCH || env.INPUT_PRERELEASE_BRANCH || 'next';
+}
+
 function releaseTag(kind) {
   return kind === 'rc' ? 'next' : 'latest';
 }
@@ -91,7 +95,7 @@ function releaseBranches(env = process.env) {
   const kind = releaseKind(env);
 
   if (kind === 'rc') {
-    return [{ name: branch, prerelease: 'rc', channel: 'next' }];
+    return ['main', { name: prereleaseBranch(env), prerelease: 'rc', channel: 'next' }];
   }
 
   if (kind === 'stable') {
@@ -170,6 +174,7 @@ function createReleaseConfig(env = process.env) {
 
 module.exports = {
   createReleaseConfig,
+  prereleaseBranch,
   releaseBranches,
   releaseKind,
   releaseTag,
diff --git a/scripts/semantic-release-config.test.mjs b/scripts/semantic-release-config.test.mjs
index f61d3498..0a267d77 100644
--- a/scripts/semantic-release-config.test.mjs
+++ b/scripts/semantic-release-config.test.mjs
@@ -10,14 +10,15 @@ function releaseExecOptions(config) {
 }
 
 describe('semantic-release config', () => {
-  it('configures manual rc releases on the selected branch with next channel', () => {
+  it('configures rc releases on a dedicated next prerelease branch', () => {
     assert.equal(releaseKind({ KTX_RELEASE_KIND: 'rc' }), 'rc');
     assert.equal(releaseTag('rc'), 'next');
-    assert.deepEqual(releaseBranches({ KTX_RELEASE_KIND: 'rc', GITHUB_REF_NAME: 'release-candidate' }), [
-      { name: 'release-candidate', prerelease: 'rc', channel: 'next' },
+    assert.deepEqual(releaseBranches({ KTX_RELEASE_KIND: 'rc', GITHUB_REF_NAME: 'main' }), [
+      'main',
+      { name: 'next', prerelease: 'rc', channel: 'next' },
     ]);
 
-    const config = createReleaseConfig({ KTX_RELEASE_KIND: 'rc', GITHUB_REF_NAME: 'release-candidate' });
+    const config = createReleaseConfig({ KTX_RELEASE_KIND: 'rc', GITHUB_REF_NAME: 'main' });
     assert.match(
       releaseExecOptions(config).prepareCmd,
       /update-public-release-version\.mjs "\$\{nextRelease\.version\}" "next"/,