From 5885d740cf9eb90ad741e4226ee456e8588f9837 Mon Sep 17 00:00:00 2001
From: Andrew Kent <andrew@braintrustdata.com>
Date: Mon, 20 Apr 2026 22:18:21 -0600
Subject: [PATCH] add fallback logic to other jaavagent detector

---
 .../dev/braintrust/system/AgentBootstrap.java | 53 +++++++++++++++----
 .../braintrust/system/AgentBootstrapTest.java | 20 +++++++
 2 files changed, 63 insertions(+), 10 deletions(-)

diff --git a/braintrust-java-agent/bootstrap/src/main/java/dev/braintrust/system/AgentBootstrap.java b/braintrust-java-agent/bootstrap/src/main/java/dev/braintrust/system/AgentBootstrap.java
index 048d2685..bdca80a0 100644
--- a/braintrust-java-agent/bootstrap/src/main/java/dev/braintrust/system/AgentBootstrap.java
+++ b/braintrust-java-agent/bootstrap/src/main/java/dev/braintrust/system/AgentBootstrap.java
@@ -117,21 +117,54 @@ static List<AgentKind> detectAgents() {
         try {
             var info = ProcessHandle.current().info();
             var arguments = info.arguments();
-            if (arguments.isEmpty()) return agents;
-            for (var arg : arguments.get()) {
-                if (!arg.startsWith("-javaagent:")) continue;
-                // Strip optional =agentargs suffix: -javaagent:/path/to.jar=args
-                var jarPath = arg.substring("-javaagent:".length());
-                var eqIdx = jarPath.indexOf('=');
-                if (eqIdx >= 0) jarPath = jarPath.substring(0, eqIdx);
-                agents.add(classifyAgentJar(jarPath));
+            if (arguments.isPresent()) {
+                for (var arg : arguments.get()) {
+                    if (!arg.startsWith("-javaagent:")) continue;
+                    agents.add(classifyAgentJar(stripAgentPath(arg)));
+                }
+            } else {
+                // arguments() is often empty on Linux; fall back to commandLine()
+                var cmdLine = info.commandLine();
+                if (cmdLine.isPresent()) {
+                    agents.addAll(detectAgentsFromCommandLine(cmdLine.get()));
+                }
             }
-        } catch (Throwable ignored) {
-            // ProcessHandle unavailable — return empty, callers fall back gracefully.
+        } catch (Throwable t) {
+            log("error detecting agents: " + t.getMessage());
+            log(t);
+        }
+        return agents;
+    }
+
+    /** Extracts {@code -javaagent:} entries from a raw command line string. */
+    static List<AgentKind> detectAgentsFromCommandLine(String cmdLine) {
+        var agents = new ArrayList<AgentKind>();
+        var prefix = "-javaagent:";
+        int idx = 0;
+        while ((idx = cmdLine.indexOf(prefix, idx)) >= 0) {
+            int start = idx + prefix.length();
+            // The jar path ends at the next whitespace (or end of string).
+            // An '=' before whitespace separates jar path from agent args.
+            int end = start;
+            while (end < cmdLine.length() && cmdLine.charAt(end) != ' ') {
+                end++;
+            }
+            var token = cmdLine.substring(start, end);
+            var eqIdx = token.indexOf('=');
+            var jarPath = eqIdx >= 0 ? token.substring(0, eqIdx) : token;
+            agents.add(classifyAgentJar(jarPath));
+            idx = end;
         }
         return agents;
     }
 
+    private static String stripAgentPath(String arg) {
+        var jarPath = arg.substring("-javaagent:".length());
+        var eqIdx = jarPath.indexOf('=');
+        if (eqIdx >= 0) jarPath = jarPath.substring(0, eqIdx);
+        return jarPath;
+    }
+
     private static AgentKind classifyAgentJar(String jarPath) {
         try (var jar = new JarFile(jarPath, false)) {
             Manifest manifest = jar.getManifest();
diff --git a/braintrust-java-agent/src/test/java/dev/braintrust/system/AgentBootstrapTest.java b/braintrust-java-agent/src/test/java/dev/braintrust/system/AgentBootstrapTest.java
index 477f195e..a508c3a5 100644
--- a/braintrust-java-agent/src/test/java/dev/braintrust/system/AgentBootstrapTest.java
+++ b/braintrust-java-agent/src/test/java/dev/braintrust/system/AgentBootstrapTest.java
@@ -168,6 +168,26 @@ void detectAgentsIncludesBraintrust() {
                 "did not expect DATADOG in plain test JVM, got: " + agents);
     }
 
+    @Test
+    void detectAgentsFromCommandLine() {
+        var cmdLine =
+                "/usr/bin/java -Dfoo=bar"
+                        + " -javaagent:/path/to/dd-java-agent-1.61.1.jar"
+                        + " -javaagent:/tmp/braintrust-java-agent.jar"
+                        + " -XX:TieredStopAtLevel=1 -cp foo.jar Main";
+        var agents = AgentBootstrap.detectAgentsFromCommandLine(cmdLine);
+        assertEquals(2, agents.size(), "expected 2 agents, got: " + agents);
+        // classifyAgentJar won't find real JARs at these paths, so both will be UNKNOWN;
+        // the important thing is that parsing found 2 -javaagent entries.
+    }
+
+    @Test
+    void detectAgentsFromCommandLineWithAgentArgs() {
+        var cmdLine = "/usr/bin/java -javaagent:/path/agent.jar=someArgs -cp foo.jar Main";
+        var agents = AgentBootstrap.detectAgentsFromCommandLine(cmdLine);
+        assertEquals(1, agents.size(), "expected 1 agent, got: " + agents);
+    }
+
     @Test
     void otelAutoconfigureProducesRealTracer() {
         assertEquals(