fix: parse XML-like function.arguments from OpenAI-compatible models

[octo-patch]

Fixes #11453

Problem

Some OpenAI-compatible models (e.g. local Qwen endpoints) return tool_calls[].function.arguments in an XML-like format rather than JSON:

<tool_call>
<function=ls>
<parameter=dirPath>src</parameter>
<parameter=recursive>True</parameter>
</function>
</tool_call>

Continue assumed JSON-only arguments in all tool-call parsing paths. When JSON.parse() failed, it silently returned {}, causing all required-argument validation to fail and tool calls to never execute correctly.

Solution

Add parseXmlToolCallArgs() to core/tools/parseArgs.ts as a fallback when JSON parsing fails. The function:

• Extracts <parameter=name>value</parameter> pairs via regex
• Applies scalar coercion: "true"/"false" → boolean, numeric strings → number, JSON-parseable strings → parsed value, everything else stays as a string

safeParseToolCallArgs() now tries XML parsing before returning {}.

The CLI streaming path (extensions/cli/src/stream/streamChatResponse.ts) also gets the same fallback: after all streaming chunks arrive, any tool call whose argumentsStr was never JSON-parseable is retried through parseXmlToolCallArgs().

Testing

• Added unit tests in core/tools/parseArgs.vitest.ts covering:
  • Full XML-wrapped payload with boolean and string params
  • Boolean coercion (True/False)
  • Numeric coercion (integer and float)
  • Plain string values that don't coerce
  • Existing JSON path is unchanged (no regression)

---

Summary by cubic

Fixes tool-call parsing when some OpenAI-compatible models return XML-like function.arguments, so tools receive correct parameters. Adds a fallback parser with simple type coercion and uses it in core parsing and CLI streaming.

• Bug Fixes
  • Added XML-like fallback in safeParseToolCallArgs(): parses <parameter=name>value</parameter> and coerces booleans, numbers, and JSON literals.
  • Applied the same fallback in the CLI streaming path after the stream ends for calls that never produced valid JSON.
  • Added tests covering XML parsing, value coercion, and no-regression for JSON inputs.

^{Written for commit f175f3b. Summary will update on new commits.}

[cubic-dev-ai]

2 issues found across 3 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="core/tools/parseArgs.ts">

<violation number="1" location="core/tools/parseArgs.ts:12">
P2: XML numeric coercion accepts non-finite numbers (e.g., `Infinity`), and downstream `getNumberArg` does not reject them.</violation>

<violation number="2" location="core/tools/parseArgs.ts:31">
P1: Model-controlled XML parameter names can pollute object prototype via `__proto__`, enabling inherited-arg presence bypasses.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review, or fix all with cubic.}

[cubic-dev-ai]

P1: Model-controlled XML parameter names can pollute object prototype via __proto__, enabling inherited-arg presence bypasses.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At core/tools/parseArgs.ts, line 31:

<comment>Model-controlled XML parameter names can pollute object prototype via `__proto__`, enabling inherited-arg presence bypasses.</comment>

<file context>
@@ -1,5 +1,46 @@
+ * <parameter=…> tags are found so callers can detect a failed parse.
+ */
+export function parseXmlToolCallArgs(argsStr: string): Record<string, any> {
+  const result: Record<string, any> = {};
+  const paramRegex = /<parameter=([^>]+)>([\s\S]*?)<\/parameter>/g;
+  let match: RegExpExecArray | null;
</file context>

Suggested change

	const result: Record<string, any> = {};
	const result: Record<string, any> = Object.create(null);

[cubic-dev-ai]

P2: XML numeric coercion accepts non-finite numbers (e.g., Infinity), and downstream getNumberArg does not reject them.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At core/tools/parseArgs.ts, line 12:

<comment>XML numeric coercion accepts non-finite numbers (e.g., `Infinity`), and downstream `getNumberArg` does not reject them.</comment>

<file context>
@@ -1,5 +1,46 @@
+  if (value.toLowerCase() === "false") return false;
+
+  // Numeric coercion — only if the string is entirely numeric
+  if (value.trim() !== "" && !isNaN(Number(value))) return Number(value);
+
+  // JSON coercion (for embedded arrays/objects/quoted strings)
</file context>

Suggested change

	if (value.trim() !== "" && !isNaN(Number(value))) return Number(value);
	const num = Number(value);
	if (value.trim() !== "" && Number.isFinite(num)) return num;