fix: accept uppercase V prefix in --tag

Fold a leading uppercase `V` (a common paste) to the canonical lowercase
`v` before validating `--tag`. The remainder of the tag stays
case-sensitive on purpose: the validated value is used verbatim as a git
ref, which is case-sensitive on GitHub, so rewriting label/build-metadata
casing could point at a tag that does not exist. Adds a normalization test.

Author: chordpli

src/specify_cli/_version.py

@@ -305,13 +305,20 @@ def _validate_tag(tag: str) -> str:
 
     Accepts vX.Y.Z plus an optional dev or alpha/beta/rc suffix and/or an
     optional build-metadata suffix, which may combine (for example:
-    v1.0.0-rc1, v0.8.0.dev0, v0.8.0+build.42, v1.0.0-rc1+build.42). Rejects
-    everything else, including bare 'latest', hash refs, branch names, and
-    numeric versions without the 'v' prefix.
+    v1.0.0-rc1, v0.8.0.dev0, v0.8.0+build.42, v1.0.0-rc1+build.42). An
+    uppercase ``V`` prefix is accepted and folded to the canonical lowercase
+    ``v``. Rejects everything else, including bare 'latest', hash refs, branch
+    names, and numeric versions without the 'v' prefix.
     """
     tag = tag.strip()
     if not tag:
         raise typer.BadParameter(_INVALID_TAG_MESSAGE)
+    # Fold a leading uppercase `V` (a common paste) to the canonical lowercase
+    # `v`. The remainder stays case-sensitive on purpose: the validated tag is
+    # used verbatim as a git ref, which is case-sensitive on GitHub, so we must
+    # not rewrite label/build-metadata casing into a ref that may not exist.
+    if tag[:1] == "V":
+        tag = "v" + tag[1:]
     if not _TAG_REGEX.match(tag):
         raise typer.BadParameter(_INVALID_TAG_MESSAGE)
     try:

tests/test_self_upgrade_verification.py

@@ -421,6 +421,21 @@ def test_valid_build_metadata_tag(self, uv_tool_argv0, clean_environ):
         assert result.exit_code == 0
         assert "Target version: v0.8.0+build.42" in strip_ansi(result.output)
 
+    def test_uppercase_v_prefix_is_folded_to_lowercase(
+        self, uv_tool_argv0, clean_environ
+    ):
+        # A pasted uppercase `V` prefix is accepted and normalized to `v` so
+        # the git ref matches the canonical lowercase release tag.
+        with patch("specify_cli._version.shutil.which", return_value="uv"), patch(
+            "specify_cli._version._get_installed_version", return_value="0.7.5"
+        ):
+            result = runner.invoke(
+                app,
+                ["self", "upgrade", "--dry-run", "--tag", "V0.7.6"],
+            )
+        assert result.exit_code == 0
+        assert "Target version: v0.7.6" in strip_ansi(result.output)
+
     def test_valid_prerelease_with_build_metadata_tag(
         self, uv_tool_argv0, clean_environ
     ):