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fix(github): handle non-JSON upstream tool responses #388

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tlgimenes merged 3 commits into from
Apr 16, 2026
+4 −0
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fix(github): handle non-JSON upstream tool responses #388

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eed574a
fix(github): handle non-JSON upstream tool responses
tlgimenes Apr 15, 2026
58eae94
debug(github): log upstream callTool response for get_file_contents
tlgimenes Apr 16, 2026
528ed6d
fix: format console.log to pass oxfmt check
tlgimenes Apr 16, 2026
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4 changes: 4 additions & 0 deletions github/server/lib/mcp-proxy.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -168,6 +168,10 @@ export function buildUpstreamTools(
name: toolDef.name,
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@cubic-dev-ai cubic-dev-ai bot Apr 16, 2026 •
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P1: Non-JSON tool responses still throw Failed to parse instead of falling back to raw text/null.

Prompt for AI agents 
Check if this issue is valid — if so, understand the root cause and fix it. At github/server/lib/mcp-proxy.ts, line 189:

<comment>Non-JSON tool responses still throw `Failed to parse` instead of falling back to raw text/null.</comment>

<file context>
@@ -185,11 +186,10 @@ export function buildUpstreamTools(
           const parsed = safeJsonParse(msg);
-          if (parsed) {
-            return parsed;
+          if (!parsed) {
+            throw new Error(`Failed to parse: ${msg}`);
           }
</file context>
Fix with Cubic

arguments: context as Record<string, unknown>,
});
console.log(
`[mcp-proxy] callTool result for ${toolDef.name}:`,
JSON.stringify(result, null, 2),
);
const contents = result.content as
| Array<{ type: string; text?: string }>
| undefined;
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