diff --git a/.github/workflows/publish-test.yml b/.github/workflows/publish-test.yml
index 12e650b..299c773 100644
--- a/.github/workflows/publish-test.yml
+++ b/.github/workflows/publish-test.yml
@@ -56,4 +56,10 @@ jobs:
       - name: Publish to TestPyPI (Trusted Publishing)
         uses: pypa/gh-action-pypi-publish@release/v1
         with:
-          repository-url: https://test.pypi.org/legacy/
\ No newline at end of file
+          repository-url: https://test.pypi.org/legacy/
+          # TestPyPI rejects re-uploads of the same wheel hash with
+          # HTTP 400 "File already exists". `skip-existing` makes
+          # re-runs of the same SHA a no-op (matching twine's
+          # --skip-existing behaviour). Production PyPI cannot
+          # overwrite anyway, so this flag is harmless there too.
+          skip-existing: true
\ No newline at end of file
diff --git a/pyproject.toml b/pyproject.toml
index 20b1e9d..9402dac 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,14 @@ build-backend = "hatchling.build"
 
 [project]
 name = "nullrun"
-version = "0.11.0"
+# Version bump: 0.11.0 → 0.12.0 in `feat(sdk)` (server-minted
+# execution_id default + capability probe). The previous commit
+# updated `src/nullrun/__version__.py` but missed this field, so
+# `python -m build` was producing a wheel named `nullrun-0.11.0-*`
+# that collided with the 0.11.0 artifact already on TestPyPI
+# (causing the publish-test workflow to fail with HTTP 400
+# "File already exists").
+version = "0.12.0"
 # Long form used by PyPI page meta-description and search snippets.
 # Kept under the 200-char preview threshold so the full line is visible
 # without an "expand" click. Keywords are matched against likely search