From 6da2b2d87e45a157f52e3dd1abd14f21e56079d7 Mon Sep 17 00:00:00 2001
From: Linus Groh <mail@linusgroh.de>
Date: Thu, 7 May 2026 22:23:41 +0100
Subject: [PATCH] Implement error stack parsing for kiesel

---
 jest.config.js        |  2 +-
 lib/agents/kiesel.js  | 38 +++++++++++++++++---------
 test/agents/kiesel.js | 62 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 88 insertions(+), 14 deletions(-)
 create mode 100644 test/agents/kiesel.js

diff --git a/jest.config.js b/jest.config.js
index 1a8223b..8e28322 100644
--- a/jest.config.js
+++ b/jest.config.js
@@ -11,7 +11,7 @@ const jestConfig = {
   //   },
   // },
   rootDir: "./",
-  testMatch: ["<rootDir>/test/*.js"],
+  testMatch: ["<rootDir>/test/*.js", "<rootDir>/test/agents/*.js"],
   testPathIgnorePatterns: [],
   transform: {},
   verbose: true,
diff --git a/lib/agents/kiesel.js b/lib/agents/kiesel.js
index d375be8..407503a 100644
--- a/lib/agents/kiesel.js
+++ b/lib/agents/kiesel.js
@@ -3,7 +3,8 @@ import fs from "node:fs";
 import * as runtimePath from "../runtime-path.js";
 import { ConsoleAgent } from "../ConsoleAgent.js";
 
-const errorRe = /^Uncaught exception: (.+?)(?:: (.+))?$/m;
+const ERROR_REGEXP = /^Uncaught exception: (?<name>.+?)(?:: (?<message>.+))?$/m;
+const STACK_FRAME_REGEXP = /^ {2}at fn (?<functionName>.+)$/;
 
 class KieselAgent extends ConsoleAgent {
   static RUNTIME = fs.readFileSync(runtimePath.for("kiesel"), "utf8");
@@ -27,30 +28,41 @@ class KieselAgent extends ConsoleAgent {
   }
 
   parseError(str) {
-    const match = str.match(errorRe);
-
-    if (!match) {
+    const errorMatch = str.match(ERROR_REGEXP);
+    if (!errorMatch) {
       return null;
     }
 
-    const name = match[1] ? match[1].trim() : "";
-    const message = match[2] ? match[2].trim() : "";
+    const { name, message = "" } = errorMatch.groups;
+    const stack = [];
+
+    const lines = str.slice(errorMatch[0].length).split(/\r?\n/g);
+    for (const line of lines) {
+      const stackFrameMatch = line.match(STACK_FRAME_REGEXP);
+      if (stackFrameMatch) {
+        const { functionName } = stackFrameMatch.groups;
+        stack.push({
+          source: line,
+          functionName,
+        });
+      }
+    }
 
     return {
       name,
       message,
-      stack: [],
+      stack,
     };
   }
 
   normalizeResult(result) {
-    const match = result.stdout.match(errorRe);
-
-    if (match) {
-      result.stdout = result.stdout.replace(errorRe, "");
-      result.stderr = match[0];
+    const errorMatch = ERROR_REGEXP.exec(result.stdout);
+    if (errorMatch) {
+      const { index } = errorMatch;
+      const stdout = result.stdout;
+      result.stdout = stdout.slice(0, index);
+      result.stderr = stdout.slice(index);
     }
-
     return result;
   }
 }
diff --git a/test/agents/kiesel.js b/test/agents/kiesel.js
new file mode 100644
index 0000000..ae05dfd
--- /dev/null
+++ b/test/agents/kiesel.js
@@ -0,0 +1,62 @@
+import KieselAgent from "../../lib/agents/kiesel.js";
+
+describe("KieselAgent", () => {
+  describe("normalizeResult", () => {
+    it("works", () => {
+      const agent = new KieselAgent();
+      const result = {
+        stdout: `ok
+Uncaught exception: Error: boom
+  at fn foo
+  at fn bar
+  at fn baz
+`,
+        stderr: "",
+        error: null,
+      };
+
+      const normalized = agent.normalizeResult(result);
+
+      expect(normalized).toEqual({
+        stdout: `ok
+`,
+        stderr: `Uncaught exception: Error: boom
+  at fn foo
+  at fn bar
+  at fn baz
+`,
+        error: null,
+      });
+    });
+  });
+
+  describe("parseError", () => {
+    it("works", () => {
+      const agent = new KieselAgent();
+      const parsed = agent.parseError(`Uncaught exception: Error: boom
+  at fn foo
+  at fn bar
+  at fn baz
+`);
+
+      expect(parsed).toEqual({
+        name: "Error",
+        message: "boom",
+        stack: [
+          {
+            source: "  at fn foo",
+            functionName: "foo",
+          },
+          {
+            source: "  at fn bar",
+            functionName: "bar",
+          },
+          {
+            source: "  at fn baz",
+            functionName: "baz",
+          },
+        ],
+      });
+    });
+  });
+});