Pin openrewrite Python package version in PythonRewriteRpc bootstrap

PythonRewriteRpc.bootstrapOpenrewrite() was running bare `pip install
openrewrite` without a version specifier, unlike the JavaScript side
which reads /META-INF/version.txt and pins `@openrewrite/rewrite@<version>`.

This meant the Python RPC could end up with a mismatched openrewrite
package version, and the existence-only check meant users could get
stuck on a stale version indefinitely.

Changes:
- Generate META-INF/version.txt in the build (PEP 440 format) so the
  Java code can read the expected Python package version at runtime
- Pin `openrewrite==<version>` in bootstrapOpenrewrite() for release
  and CI builds; skip pinning for local .dev0 builds
- Track installed version via a marker file to detect and upgrade
  stale installs
- Add license exclude for version.txt and .gitignore entry

Author: knutwannheden

rewrite-python/.gitignore

@@ -0,0 +1 @@
+src/main/resources/META-INF/version.txt

rewrite-python/build.gradle.kts

@@ -1,5 +1,6 @@
 @file:Suppress("UnstableApiUsage")
 
+import nl.javadude.gradle.plugins.license.LicenseExtension
 import java.time.LocalDateTime
 import java.time.format.DateTimeFormatter
 
@@ -196,7 +197,7 @@ tasks.withType<Test> {
 // This is separate from Gradle because IntelliJ's Gradle integration doesn't support Python source roots.
 
 // ============================================
-// Python Publishing Tasks (PyPI)
+// Version Resource (for RPC version pinning)
 // ============================================
 
 // Generate a PEP 440 compliant version for CI builds
@@ -211,6 +212,31 @@ val pythonVersion: String = if (System.getenv("CI") != null) {
     project.version.toString().replace("-SNAPSHOT", ".dev0")
 }
 
+// Write version.txt resource so PythonRewriteRpc can pin the pip package version
+val generateVersionTxt by tasks.registering {
+    group = "python"
+    description = "Generate META-INF/version.txt for RPC version pinning"
+
+    val versionTxt = file("src/main/resources/META-INF/version.txt")
+    inputs.property("version", pythonVersion)
+    outputs.file(versionTxt)
+
+    doLast {
+        versionTxt.parentFile.mkdirs()
+        versionTxt.writeText(pythonVersion)
+    }
+}
+
+listOf("sourcesJar", "processResources", "licenseMain", "assemble").forEach {
+    tasks.named(it) {
+        dependsOn(generateVersionTxt)
+    }
+}
+
+// ============================================
+// Python Publishing Tasks (PyPI)
+// ============================================
+
 // Task to update version in pyproject.toml
 val pythonUpdateVersion by tasks.registering {
     group = "python"
@@ -364,3 +390,7 @@ val printTestClasspath by tasks.registering {
     }
 }
 
+extensions.configure<LicenseExtension> {
+    exclude("**/version.txt")
+}
+

rewrite-python/src/main/java/org/openrewrite/python/rpc/PythonRewriteRpc.java

@@ -19,6 +19,7 @@
 import lombok.RequiredArgsConstructor;
 import org.jspecify.annotations.Nullable;
 import org.openrewrite.*;
+import org.openrewrite.internal.StringUtils;
 import org.openrewrite.marketplace.RecipeBundleResolver;
 import org.openrewrite.marketplace.RecipeMarketplace;
 import org.openrewrite.python.*;
@@ -607,19 +608,36 @@ public PythonRewriteRpc get() {
          * This is required for the RPC server to start.
          */
         private void bootstrapOpenrewrite(Path pipPackagesPath) {
-            Path rewriteModule = pipPackagesPath.resolve("rewrite");
-            if (Files.exists(rewriteModule)) {
-                return; // Already installed
+            String version = StringUtils.readFully(
+                    PythonRewriteRpc.class.getResourceAsStream("/META-INF/version.txt"));
+            boolean pinVersion = !version.isEmpty() && !version.endsWith(".dev0");
+
+            Path versionMarker = pipPackagesPath.resolve(".openrewrite-version");
+            if (Files.exists(pipPackagesPath.resolve("rewrite"))) {
+                // Already installed — check if version matches
+                if (!pinVersion) {
+                    return;
+                }
+                try {
+                    if (Files.exists(versionMarker) &&
+                            version.equals(new String(Files.readAllBytes(versionMarker), StandardCharsets.UTF_8).trim())) {
+                        return; // Correct version already installed
+                    }
+                } catch (IOException ignored) {
+                    // Can't read marker, reinstall to be safe
+                }
             }
 
+            String packageSpec = pinVersion ? "openrewrite==" + version : "openrewrite";
+
             try {
                 Files.createDirectories(pipPackagesPath);
 
                 ProcessBuilder pb = new ProcessBuilder(
                         pythonPath.toString(),
                         "-m", "pip", "install",
                         "--target=" + pipPackagesPath.toAbsolutePath().normalize(),
-                        "openrewrite"
+                        packageSpec
                 );
                 pb.redirectErrorStream(true);
                 if (log != null) {
@@ -652,6 +670,11 @@ private void bootstrapOpenrewrite(Path pipPackagesPath) {
                 if (exitCode != 0) {
                     throw new RuntimeException("Failed to bootstrap openrewrite package, pip install exited with code " + exitCode);
                 }
+
+                // Write version marker so we can detect stale installs
+                if (pinVersion) {
+                    Files.write(versionMarker, version.getBytes(StandardCharsets.UTF_8));
+                }
             } catch (IOException e) {
                 throw new UncheckedIOException("Failed to bootstrap openrewrite package", e);
             } catch (InterruptedException e) {