fix: add classpath hint to find_agent_jar for Gradle JAR resolution

Gradle resolves the codeflash-runtime JAR to ~/.gradle/caches/, not
~/.m2/. Add an optional classpath parameter to find_agent_jar() that
searches the resolved classpath for the JAR before falling back to
the existing ~/.m2 / resources / dev-build chain.

Thread the parameter through build_javaagent_arg, build_agent_env,
instrument_source_for_line_profiler, and line_profiler_step so the
optimization pipeline passes the resolved classpath automatically.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

codeflash/languages/java/function_optimizer.py

@@ -404,7 +404,9 @@ class JavaFunctionOptimizer(FunctionOptimizer):
             line_profiler_output_path = get_run_tmp_file(Path("line_profiler_output.json"))
 
             success = self.language_support.instrument_source_for_line_profiler(
-                func_info=self.function_to_optimize, line_profiler_output_file=line_profiler_output_path
+                func_info=self.function_to_optimize,
+                line_profiler_output_file=line_profiler_output_path,
+                project_classpath=self._get_project_classpath(),
             )
             if not success:
                 return {"timings": {}, "unit": 0, "str_out": ""}

codeflash/languages/java/line_profiler.py

@@ -13,6 +13,7 @@ from __future__ import annotations
 
 import json
 import logging
+import os
 import re
 from pathlib import Path
 from typing import TYPE_CHECKING, Any
@@ -130,9 +131,9 @@ class JavaLineProfiler:
         config_output_path.write_text(json.dumps(config, indent=2), encoding="utf-8")
         return config_output_path
 
-    def build_javaagent_arg(self, config_path: Path) -> str:
+    def build_javaagent_arg(self, config_path: Path, classpath: str | None = None) -> str:
         """Return the -javaagent JVM argument string."""
-        agent_jar = find_agent_jar()
+        agent_jar = find_agent_jar(classpath=classpath)
         if agent_jar is None:
             msg = f"{AGENT_JAR_NAME} not found in resources or dev build directory"
             raise FileNotFoundError(msg)
@@ -565,12 +566,20 @@ def find_method_for_line(
     return Path(file_path).name, line_num
 
 
-def find_agent_jar() -> Path | None:
+def find_agent_jar(classpath: str | None = None) -> Path | None:
     """Locate the profiler agent JAR file (now bundled in codeflash-runtime).
 
-    Checks local Maven repo, package resources, and development build directory.
+    Checks the resolved classpath (if provided), local Maven repo, package resources,
+    and development build directory.
     """
-    # Check local Maven repository first (fastest)
+    # Check resolved classpath first (Gradle projects resolve here, not ~/.m2)
+    if classpath:
+        for entry in classpath.split(os.pathsep):
+            jar_path = Path(entry)
+            if "codeflash-runtime" in jar_path.name and jar_path.suffix == ".jar" and jar_path.exists():
+                return jar_path
+
+    # Check local Maven repository (Maven projects resolve here)
     m2_jar = (
         Path.home()
         / ".m2"

codeflash/languages/java/support.py

@@ -590,7 +590,7 @@ class JavaSupport(LanguageSupport):
         )
 
     def instrument_source_for_line_profiler(
-        self, func_info: FunctionToOptimize, line_profiler_output_file: Path
+        self, func_info: FunctionToOptimize, line_profiler_output_file: Path, project_classpath: str | None = None
     ) -> bool:
         """Prepare line profiling via the bytecode-instrumentation agent.
 
@@ -602,6 +602,7 @@ class JavaSupport(LanguageSupport):
         Args:
             func_info: Function to profile.
             line_profiler_output_file: Path where profiling results will be written by the agent.
+            project_classpath: Resolved classpath from the build tool, used to locate the agent JAR.
 
         Returns:
             True if preparation succeeded, False otherwise.
@@ -619,7 +620,7 @@ class JavaSupport(LanguageSupport):
                 source=source, file_path=func_info.file_path, functions=[func_info], config_output_path=config_path
             )
 
-            self.line_profiler_agent_arg = profiler.build_javaagent_arg(config_path)
+            self.line_profiler_agent_arg = profiler.build_javaagent_arg(config_path, classpath=project_classpath)
             self.line_profiler_warmup_iterations = profiler.warmup_iterations
             return True
         except Exception:

codeflash/languages/java/tracer.py

@@ -132,9 +132,9 @@ class JavaTracer:
         env["JAVA_TOOL_OPTIONS"] = f"{existing} {jfr_opts}".strip()
         return env
 
-    def build_agent_env(self, config_path: Path) -> dict[str, str]:
+    def build_agent_env(self, config_path: Path, classpath: str | None = None) -> dict[str, str]:
         env = os.environ.copy()
-        agent_jar = find_agent_jar()
+        agent_jar = find_agent_jar(classpath=classpath)
         if agent_jar is None:
             msg = "codeflash-runtime JAR not found, cannot run tracing agent"
             raise FileNotFoundError(msg)