fix(backend): filter PEP 440 .dev versions in fuzzy version matching

e2e/backend/test_dev_version_filter

@@ -0,0 +1,48 @@
+#!/usr/bin/env bash
+
+# Test that PEP 440 .dev versions are filtered out during fuzzy version matching
+# Regression test for https://github.com/jdx/mise/discussions/8784
+#
+# The bug: VERSION_REGEX only catches "-dev" (hyphen) but not ".dev" (dot),
+# so PEP 440 dev versions like "2026.3.3.162408.dev0" slip through the
+# pre-release filter and incorrectly satisfy a request for "2026.3.3".
+
+# Create a custom plugin that returns versions including .dev suffixes
+PLUGIN_DIR="$MISE_DATA_DIR/plugins/devtest"
+mkdir -p "$PLUGIN_DIR/bin"
+
+cat <<'LISTALL' >"$PLUGIN_DIR/bin/list-all"
+#!/usr/bin/env bash
+echo "2026.3.2 2026.3.3.dev0 2026.3.3 2026.3.3.162408.dev0 2026.3.4.dev1"
+LISTALL
+chmod +x "$PLUGIN_DIR/bin/list-all"
+
+cat <<'INSTALL' >"$PLUGIN_DIR/bin/install"
+#!/usr/bin/env bash
+mkdir -p "$ASDF_INSTALL_PATH/bin"
+cat <<EOF >"$ASDF_INSTALL_PATH/bin/devtest"
+#!/usr/bin/env bash
+echo "devtest $ASDF_INSTALL_VERSION"
+EOF
+chmod +x "$ASDF_INSTALL_PATH/bin/devtest"
+INSTALL
+chmod +x "$PLUGIN_DIR/bin/install"
+
+# Test 1: latest for "2026.3.3" should return exactly "2026.3.3", not a dev version
+assert "mise latest devtest@2026.3.3" "2026.3.3"
+
+# Test 2: latest for "2026.3" should return "2026.3.3" (highest stable), not a dev version
+assert "mise latest devtest@2026.3" "2026.3.3"
+
+# Test 3: If user explicitly requests a dev version by exact match, it should work
+mise install devtest@2026.3.3.dev0
+assert_contains "mise x devtest@2026.3.3.dev0 -- devtest" "2026.3.3.dev0"
+
+# Test 4: Install stable version, then verify it resolves correctly even with
+# the dev version already installed (core bug from the discussion)
+mise install devtest@2026.3.3
+assert_contains "mise x devtest@2026.3.3 -- devtest" "devtest 2026.3.3"
+assert_not_contains "mise x devtest@2026.3.3 -- devtest" "dev0"
+
+# Test 5: latest for a version that only has dev releases should return nothing
+assert_empty "mise latest devtest@2026.3.4"

src/plugins/mod.rs

@@ -216,7 +216,7 @@ pub fn warn_if_env_plugin_shadows_registry(name: &str, plugin_path: &Path) {
 
 pub static VERSION_REGEX: Lazy<regex::Regex> = Lazy::new(|| {
     Regex::new(
-        r"(?i)(^Available versions:|-src|-dev|-latest|-stm|[-\\.]rc|-milestone|-alpha|-beta|[-\\.]pre|-next|-test|([abc])[0-9]+|snapshot|SNAPSHOT|master)"
+        r"(?i)(^Available versions:|-src|[-\\.]dev|-latest|-stm|[-\\.]rc|-milestone|-alpha|-beta|[-\\.]pre|-next|-test|([abc])[0-9]+|snapshot|SNAPSHOT|master)"
     )
         .unwrap()
 });
@@ -426,4 +426,31 @@ mod tests {
             _ => panic!("Expected a git plugin"),
         }
     }
+
+    #[test]
+    fn test_version_regex_filters_prerelease() {
+        // Standard pre-release patterns
+        assert!(VERSION_REGEX.is_match("1.0.0-alpha"));
+        assert!(VERSION_REGEX.is_match("1.0.0-beta"));
+        assert!(VERSION_REGEX.is_match("1.0.0-rc1"));
+        assert!(VERSION_REGEX.is_match("1.0.0.rc1"));
+        assert!(VERSION_REGEX.is_match("1.0.0-dev"));
+        assert!(VERSION_REGEX.is_match("1.0.0-pre1"));
+        assert!(VERSION_REGEX.is_match("1.0.0.pre1"));
+
+        // PEP 440 dot-separated dev versions (GitHub discussion #8784)
+        assert!(
+            VERSION_REGEX.is_match("2026.3.3.dev0"),
+            "PEP 440 .dev suffix should be filtered"
+        );
+        assert!(
+            VERSION_REGEX.is_match("2026.3.3.162408.dev0"),
+            "PEP 440 .dev suffix with build number should be filtered"
+        );
+
+        // Stable versions should NOT match
+        assert!(!VERSION_REGEX.is_match("1.0.0"));
+        assert!(!VERSION_REGEX.is_match("2026.3.3"));
+        assert!(!VERSION_REGEX.is_match("22.6.0"));
+    }
 }