fix: propagate mermaid-cli stderr in rendering errors#83
Merged
veelenga merged 3 commits intoveelenga:mainfrom Mar 10, 2026
Merged
fix: propagate mermaid-cli stderr in rendering errors#83veelenga merged 3 commits intoveelenga:mainfrom
veelenga merged 3 commits intoveelenga:mainfrom
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When mermaid-cli fails, execFileAsync throws with `.stderr` containing
the actual parse error details (e.g., "Parse error on line 3..."), but
only the generic `error.message` ("Command failed: npx ...") was
surfaced to the MCP response. This made it impossible for Claude to
self-correct Mermaid syntax errors.
Extract stderr from the caught error and include it in the thrown Error
message so that detailed diagnostics reach the MCP client.
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When mermaid-cli fails, execFileAsync throws with
.stderrcontaining the actual parse error details (e.g., "Parse error on line 3..."), but only the genericerror.message("Command failed: npx ...") was surfaced to the MCP response. This made it difficult for Claude to self-correct Mermaid syntax errors.Extract stderr from the caught error and include it in the thrown Error message so that detailed diagnostics reach the MCP client.