- Create patterns/ directory with README, manifest, and 10 initial patterns covering Ollama JSON fallback, API escaping, deprecation, PTY auth, queue-poll, LLM-as-parser, credential rotation, reverse proxy binding, human approval gates, and transient retry. - Wire pattern loading into architecture/pipeline.js based on task tags. - Update architecture/orchestrator.js to load patterns and surface them in the system prompt. - Update MEMORY.md, ARCHITECTURE.md, and CONTEXT.md to document the registry and record the decision.
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Pattern: JSON Escaping for Downstream APIs
Symptom
An n8n workflow passes LLM-generated text into a downstream API call, and the request fails with a JSON parse error, malformed payload, or unexpected truncation. The generated text contains quotes, newlines, backslashes, emojis, or control characters that break JSON encoding.
Affected Projects
- LinkedIn content automation (LinkedIn REST API posts)
- AI video generation pipeline (ComfyUI / JSON2Video payloads)
- Any n8n workflow that injects LLM output into an HTTP Request node body
Root Cause
LLMs produce human-readable text; downstream APIs consume machine-readable JSON. Naive string concatenation or weak JSON serialization allows unescaped characters to corrupt the payload. The failure often appears at the receiving API, making root-cause diagnosis slower.
Standard Fix
- Treat LLM output as untrusted string data.
- Always serialize it through a proper JSON encoder (
JSON.stringifyin JS,json.dumpsin Python) before embedding in a payload. - If building a payload string manually, escape quotes, backslashes, newlines, and control characters; better, avoid manual string building entirely.
- Add a validation step that parses the final payload with
JSON.parsebefore sending. - For n8n, prefer expression mapping through structured fields rather than raw body strings.
When to Apply
- Any new integration where LLM-generated content becomes part of an API request body.
- Any HTTP Request node in n8n that builds a JSON body from expressions containing LLM output.
Verification
- Test with adversarial LLM output containing quotes, newlines, unicode, and backslashes.
- Confirm the receiving API parses the payload correctly.
- Log payload shape (without secrets) for debugging.
Related Patterns
ollama-structured-output-fallbackllm-as-parser-fallback