diff --git a/.github/workflows/package-check.yml b/.github/workflows/package-check.yml
new file mode 100644
index 0000000..b5336d2
--- /dev/null
+++ b/.github/workflows/package-check.yml
@@ -0,0 +1,58 @@
+name: Package Check
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: package-check-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  package-check:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          fetch-depth: 1
+          persist-credentials: false
+
+      - uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
+        with:
+          python-version: "3.12"
+
+      - name: Install build tooling
+        uses: ./.github/actions/setup-hatch
+
+      - name: Install test and distribution tooling
+        run: python -m pip install ".[test]" "twine>=4.0.0"
+
+      - name: Run unit tests
+        run: python -m pytest -q tests/unit
+
+      - name: Build distributions
+        run: hatch build
+
+      - name: Validate distributions
+        run: python -m twine check dist/*
+
+      - name: Install and smoke-test wheel
+        run: |
+          python -m venv "$RUNNER_TEMP/package-check"
+          "$RUNNER_TEMP/package-check/bin/pip" install --upgrade pip
+          "$RUNNER_TEMP/package-check/bin/pip" install dist/*.whl
+          "$RUNNER_TEMP/package-check/bin/python" -c "import socketdev; from socketdev.version import __version__; print('wheel smoke OK', __version__)"
+
+      - name: Upload distributions
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: socketdev-${{ github.sha }}
+          path: dist/*
+          if-no-files-found: error
+          retention-days: 14
diff --git a/.github/workflows/pr-preview.yml b/.github/workflows/pr-preview.yml
index 27f7711..0493175 100644
--- a/.github/workflows/pr-preview.yml
+++ b/.github/workflows/pr-preview.yml
@@ -1,141 +1,198 @@
-name: PR Preview
+name: Publish PR Preview
+
 on:
   pull_request:
-    types: [opened, synchronize, ready_for_review]
+    types: [labeled]
+  workflow_dispatch:
+    inputs:
+      pr_number:
+        description: Pull request number to publish
+        required: true
+        type: string
 
-# Cancel an in-flight preview when the PR is pushed again -- previews publish
-# to Test PyPI, so superseded runs shouldn't keep churning.
 concurrency:
-  group: pr-preview-${{ github.event.pull_request.number }}
-  cancel-in-progress: true
+  group: publish-pr-preview-${{ github.event.pull_request.number || github.run_id }}
+  cancel-in-progress: false
 
 jobs:
-  preview:
-    # Skip on:
-    #  - PRs from forks (no access to publish secrets / OIDC)
-    #  - Dependabot PRs: preview-publishing a dependency bump to Test PyPI is
-    #    pointless (no package version bump) and would fail the version check.
+  context:
     if: >-
-      github.event.pull_request.head.repo.full_name == github.repository &&
-      github.event.pull_request.user.login != 'dependabot[bot]'
+      github.event_name == 'workflow_dispatch' ||
+      (github.event.label.name == 'publish-preview' &&
+      github.event.pull_request.head.repo.full_name == github.repository)
     runs-on: ubuntu-latest
+    timeout-minutes: 5
     permissions:
-      id-token: write
       contents: read
-      pull-requests: write
+      pull-requests: read
+    outputs:
+      pr_number: ${{ steps.context.outputs.pr_number }}
+      head_sha: ${{ steps.context.outputs.head_sha }}
+    steps:
+      - name: Validate pull request context
+        id: context
+        uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
+        env:
+          DEFAULT_BRANCH: ${{ github.event.repository.default_branch }}
+          EVENT_PR_NUMBER: ${{ github.event.pull_request.number }}
+          INPUT_PR_NUMBER: ${{ inputs.pr_number }}
+          WORKFLOW_REF: ${{ github.ref }}
+        with:
+          script: |
+            const rawPrNumber = context.eventName === 'workflow_dispatch'
+              ? process.env.INPUT_PR_NUMBER
+              : process.env.EVENT_PR_NUMBER;
+            if (!/^[1-9][0-9]*$/.test(rawPrNumber || '')) {
+              core.setFailed('Pull request number must contain ASCII digits only.');
+              return;
+            }
+
+            if (context.eventName === 'workflow_dispatch') {
+              const defaultRef = `refs/heads/${process.env.DEFAULT_BRANCH}`;
+              if (process.env.WORKFLOW_REF !== defaultRef) {
+                core.setFailed(`Run manual previews from ${defaultRef}.`);
+                return;
+              }
+            }
+
+            const prNumber = Number(rawPrNumber);
+            if (!Number.isSafeInteger(prNumber)) {
+              core.setFailed('Pull request number is outside the supported range.');
+              return;
+            }
+            const {data: pullRequest} = await github.rest.pulls.get({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              pull_number: prNumber,
+            });
+            if (pullRequest.state !== 'open') {
+              core.setFailed(`Pull request #${prNumber} is not open.`);
+              return;
+            }
+            if (pullRequest.head.repo?.full_name !== `${context.repo.owner}/${context.repo.repo}`) {
+              core.setFailed('Preview publication is limited to branches in this repository.');
+              return;
+            }
+
+            core.setOutput('pr_number', String(prNumber));
+            core.setOutput('head_sha', pullRequest.head.sha);
+
+  build:
+    needs: context
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    permissions:
+      contents: read
+    outputs:
+      preview_version: ${{ steps.version.outputs.preview_version }}
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
+          ref: ${{ needs.context.outputs.head_sha }}
           fetch-depth: 0
           persist-credentials: false
+
       - uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
         with:
-          python-version: '3.13'
+          python-version: "3.12"
 
       - name: Install build tooling
         uses: ./.github/actions/setup-hatch
 
-      - name: Inject full dynamic version
-        run: python .hooks/sync_version.py --dev
+      - name: Install distribution validator
+        run: python -m pip install "twine>=4.0.0"
 
-      - name: Check if version exists on Test PyPI
-        id: version_check
+      - name: Inject deterministic preview version
+        env:
+          PREVIEW_ID: ${{ github.run_id }}
+          RUN_ATTEMPT: ${{ github.run_attempt }}
         run: |
-          VERSION=$(hatch version | cut -d+ -f1)
-          echo "VERSION=$VERSION" >> $GITHUB_ENV
-          if curl -s -f https://test.pypi.org/pypi/socketdev/$VERSION/json > /dev/null; then
-            echo "Version ${VERSION} already exists on Test PyPI"
-            echo "exists=true" >> $GITHUB_OUTPUT
-          else
-            echo "Version ${VERSION} not found on Test PyPI - proceeding with test deployment"
-            echo "exists=false" >> $GITHUB_OUTPUT
-          fi
-
-      - name: Clean previous builds
-        run: rm -rf dist/ build/ *.egg-info
-
-      - name: Get Hatch version
+          PREVIEW_ID=$((PREVIEW_ID * 100 + RUN_ATTEMPT))
+          python .hooks/sync_version.py --dev --preview-id "$PREVIEW_ID" --skip-lock
+
+      - name: Read preview version
         id: version
-        run: |
-          VERSION=$(hatch version | cut -d+ -f1)
-          echo "VERSION=$VERSION" >> $GITHUB_ENV
+        run: echo "preview_version=$(hatch version)" >> "$GITHUB_OUTPUT"
 
-      - name: Build package
-        if: steps.version_check.outputs.exists != 'true'
+      - name: Build and validate distributions
         run: |
           hatch build
+          python -m twine check dist/*
+
+      - name: Install and smoke-test wheel locally
+        run: |
+          python -m venv "$RUNNER_TEMP/preview-check"
+          "$RUNNER_TEMP/preview-check/bin/pip" install --upgrade pip
+          "$RUNNER_TEMP/preview-check/bin/pip" install dist/*.whl
+          "$RUNNER_TEMP/preview-check/bin/python" -c "import socketdev; from socketdev.version import __version__; print('preview wheel smoke OK', __version__)"
+
+      - name: Upload preview distributions
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: socketdev-preview-${{ github.run_id }}-${{ github.run_attempt }}
+          path: dist/*
+          if-no-files-found: error
+          retention-days: 14
+
+  publish:
+    needs: [context, build]
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    permissions:
+      contents: read
+      id-token: write
+      pull-requests: write
+    steps:
+      - name: Download preview distributions
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
+        with:
+          name: socketdev-preview-${{ github.run_id }}-${{ github.run_attempt }}
+          path: dist
 
-      - name: Publish to Test PyPI
-        if: steps.version_check.outputs.exists != 'true'
+      - name: Publish to TestPyPI
         uses: pypa/gh-action-pypi-publish@dc37677b2e1c63e2034f94d8a5b11f265b73ba33 # v1.14.2
         with:
           repository-url: https://test.pypi.org/legacy/
           verbose: true
 
-      - name: Comment on PR
-        if: steps.version_check.outputs.exists != 'true'
+      - name: Comment on pull request
         uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
         env:
-          VERSION: ${{ env.VERSION }}
+          PREVIEW_VERSION: ${{ needs.build.outputs.preview_version }}
+          PR_NUMBER: ${{ needs.context.outputs.pr_number }}
         with:
           script: |
-            const version = process.env.VERSION;
-            const prNumber = context.payload.pull_request.number;
-            const owner = context.repo.owner;
-            const repo = context.repo.repo;
-            // Find existing bot comments
-            const comments = await github.rest.issues.listComments({
+            const marker = '<!-- socketdev-pr-preview -->';
+            const prNumber = Number(process.env.PR_NUMBER);
+            const version = process.env.PREVIEW_VERSION;
+            const body = `${marker}
+            🚀 SDK preview published: \`socketdev==${version}\`
+
+            \`\`\`bash
+            pip install --index-url https://test.pypi.org/simple/ --extra-index-url https://pypi.org/simple socketdev==${version}
+            \`\`\`
+
+            TestPyPI's package index can take several minutes to expose a newly uploaded version.`;
+            const {data: comments} = await github.rest.issues.listComments({
               owner: context.repo.owner,
               repo: context.repo.repo,
               issue_number: prNumber,
             });
-
-            const botComment = comments.data.find(comment =>
-              comment.user.type === 'Bot' &&
-              comment.body.includes('🚀 Preview package published!')
+            const existing = comments.find(comment =>
+              comment.user.type === 'Bot' && comment.body.includes(marker)
             );
-
-            const comment = `
-            🚀 Preview package published!
-
-            Install with:
-            \`\`\`bash
-            pip install --index-url https://test.pypi.org/simple/ --extra-index-url https://pypi.org/simple socketdev==${version}
-            \`\`\``;
-
-            if (botComment) {
-              // Update existing comment
+            if (existing) {
               await github.rest.issues.updateComment({
-                owner: owner,
-                repo: repo,
-                comment_id: botComment.id,
-                body: comment
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                comment_id: existing.id,
+                body,
               });
             } else {
-              // Create new comment
               await github.rest.issues.createComment({
-                owner: owner,
-                repo: repo,
+                owner: context.repo.owner,
+                repo: context.repo.repo,
                 issue_number: prNumber,
-                body: comment
+                body,
               });
             }
-
-      - name: Verify package is available
-        if: steps.version_check.outputs.exists != 'true'
-        id: verify_package
-        env:
-          VERSION: ${{ env.VERSION }}
-        run: |
-          for i in {1..30}; do
-            if pip install --index-url 'https://test.pypi.org/simple/' --extra-index-url 'https://pypi.org/simple' socketdev==${VERSION}; then
-              echo "Package ${VERSION} is now available and installable on Test PyPI"
-              pip uninstall -y socketdev
-              echo "success=true" >> $GITHUB_OUTPUT
-              exit 0
-            fi
-            echo "Attempt $i: Package not yet installable, waiting 20s... (${i}/30)"
-            sleep 20
-          done
-          echo "success=false" >> $GITHUB_OUTPUT
-          exit 1
diff --git a/.hooks/sync_version.py b/.hooks/sync_version.py
index 7a8ab24..32869c3 100755
--- a/.hooks/sync_version.py
+++ b/.hooks/sync_version.py
@@ -124,13 +124,44 @@ def run_uv_lock() -> bool:
     return before != after
 
 
+def read_preview_id():
+    if "--preview-id" not in sys.argv:
+        return None
+
+    option_index = sys.argv.index("--preview-id")
+    try:
+        preview_id = sys.argv[option_index + 1]
+    except IndexError:
+        print("❌ `--preview-id` requires a numeric value.")
+        sys.exit(1)
+
+    if not preview_id.isascii() or not preview_id.isdigit():
+        print("❌ `--preview-id` must contain ASCII digits only.")
+        sys.exit(1)
+    return preview_id
+
+
 def main():
     dev_mode = "--dev" in sys.argv
+    skip_lock = "--skip-lock" in sys.argv
+    preview_id = read_preview_id()
     current_version = read_version_from_version_file(VERSION_FILE)
     previous_version = read_version_from_git("socketdev/version.py")
 
     print(f"Current: {current_version}, Previous: {previous_version}")
 
+    if preview_id is not None:
+        if not dev_mode:
+            print("❌ `--preview-id` can only be used with `--dev`.")
+            sys.exit(1)
+        base_version = current_version.split(".dev")[0]
+        new_version = f"{base_version}.dev{preview_id}"
+        inject_version(new_version)
+        if not skip_lock:
+            run_uv_lock()
+        print(f"✅ Prepared deterministic preview version {new_version}.")
+        sys.exit(0)
+
     if current_version == previous_version:
         if dev_mode:
             base_version = current_version.split(".dev")[0] if ".dev" in current_version else current_version
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 0000000..5775220
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,49 @@
+# Contributing
+
+## Development setup
+
+Use Python 3.9 or newer. Create and activate a virtual environment, then
+install the package with its development and test dependencies:
+
+```bash
+python -m venv .venv
+source .venv/bin/activate
+python -m pip install -e ".[dev,test]"
+```
+
+Before opening a pull request, run the focused checks for your change. The
+complete local check is:
+
+```bash
+python -m pytest
+hatch build
+python -m twine check dist/*
+```
+
+## Pull request validation
+
+The `Package Check` workflow runs automatically for pull requests. It runs the
+unit tests, builds and validates the distributions, smoke-tests the wheel, and
+uploads the distributions as workflow artifacts. It does not publish a package.
+
+## Publishing a pull request preview
+
+Preview publication is intentionally opt-in. Only request a preview for code
+that is trusted to run with the repository's publishing permissions.
+
+For a pull request from this repository, apply the `publish-preview` label. The
+`Publish PR Preview` workflow will build and validate a uniquely versioned
+`socketdev` prerelease, publish it to TestPyPI, and add or update a pull request
+comment with the exact version and installation command. Both label-triggered
+and manually dispatched previews are limited to open pull requests whose
+branches belong to this repository.
+
+The workflow reacts when the label is added; pushing another commit while the
+label remains on the pull request does not publish a new preview. To publish the
+new pull request head or retry a failed publication, remove `publish-preview`
+and apply it again.
+
+Maintainers can also open **Actions > Publish PR Preview > Run workflow**, run
+it from the repository's default branch, and enter the pull request number.
+Manual dispatch is useful when a label should remain unchanged or a
+publication needs to be retried.