fix: address stack trace review feedback

Cap clipboard prefill content, clarify command registration readiness, and add regression coverage for shared stack frame parsing.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 6e50dc26-84c4-4532-a7d3-88f6fe016780

Author: wenytang-ms

src/stackTraceLinkProvider.ts

@@ -27,8 +27,9 @@ const MAX_LINKS_PER_DOCUMENT = 2000;
 // Only resolve to source locations the language server is expected to return.
 const ALLOWED_SOURCE_SCHEMES = new Set<string>(["file", "jdt"]);
 
-// Cap how much of the clipboard we scan when deciding whether to prefill (ReDoS hygiene).
-const MAX_CLIPBOARD_SCAN_LENGTH = 20000;
+// Bound both stack-trace detection and scratch-document prefill so a large clipboard cannot create
+// an expensive untitled document (and keeps the detection regex input bounded).
+const MAX_CLIPBOARD_PREFILL_LENGTH = 20000;
 
 interface IStackFrameLinkArgs {
     stackTrace: string;
@@ -131,15 +132,16 @@ async function analyzeStackTrace(): Promise<void> {
     // The command itself is auto-instrumented via instrumentOperationAsVsCodeCommand, so no
     // manual telemetry is needed here to track invocations.
     const clipboard = await env.clipboard.readText();
-    const looksLikeTrace = parseJavaStackFrame(clipboard.slice(0, MAX_CLIPBOARD_SCAN_LENGTH)) !== undefined;
-    const content = looksLikeTrace ? clipboard : "";
+    const clipboardContent = clipboard.slice(0, MAX_CLIPBOARD_PREFILL_LENGTH);
+    const looksLikeTrace = parseJavaStackFrame(clipboardContent) !== undefined;
+    const content = looksLikeTrace ? clipboardContent : "";
     const document = await workspace.openTextDocument({ language: "log", content });
     await window.showTextDocument(document);
 }
 
 export function registerStackTraceLinkProvider(context: ExtensionContext): void {
-    // The commands are always available: the palette command must not depend on server
-    // readiness, and the click handler is only ever reached from links the provider creates.
+    // Register handlers immediately for programmatic invocations and existing command links.
+    // Palette visibility and creation of new links are gated on language-server readiness elsewhere.
     context.subscriptions.push(
         commands.registerCommand(NAVIGATE_TO_STACK_FRAME_COMMAND, navigateToStackFrame),
         instrumentOperationAsVsCodeCommand(ANALYZE_STACK_TRACE_COMMAND, analyzeStackTrace),

test/stackFrameParser.test.ts

@@ -0,0 +1,43 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license.
+
+import * as assert from "assert";
+
+import { parseJavaStackFrame } from "../src/stackFrameParser";
+
+suite("parseJavaStackFrame", () => {
+    test("parses a tab-indented stack frame", () => {
+        const stackTrace = "com.example.App.main(App.java:42)";
+
+        assert.deepStrictEqual(parseJavaStackFrame(`\tat ${stackTrace}`), {
+            stackTrace,
+            methodName: "com.example.App.main",
+            lineNumber: 42,
+            startIndex: 4,
+            length: stackTrace.length,
+        });
+    });
+
+    test("preserves a module prefix", () => {
+        const stackTrace = "java.base/java.util.ArrayList.forEach(ArrayList.java:1511)";
+
+        assert.deepStrictEqual(parseJavaStackFrame(`\tat ${stackTrace}`), {
+            stackTrace,
+            methodName: "java.util.ArrayList.forEach",
+            lineNumber: 1511,
+            startIndex: 4,
+            length: stackTrace.length,
+        });
+    });
+
+    test("calculates the link range within prefixed output", () => {
+        const stackTrace = "com.example.Worker.run(Worker.java:7)";
+        const line = `[stderr] \tat ${stackTrace} ~[app.jar:1.0]`;
+        const frame = parseJavaStackFrame(line);
+
+        assert.ok(frame);
+        assert.strictEqual(frame.startIndex, line.indexOf(stackTrace));
+        assert.strictEqual(frame.length, stackTrace.length);
+        assert.strictEqual(line.substring(frame.startIndex, frame.startIndex + frame.length), stackTrace);
+    });
+});