`removeCodeBlocks` fails to strip markdown fences from truncated LLM responses

[bsmoreno2910]

🐛 Describe the bug

Bug Description

removeCodeBlocks uses a regex that requires both opening and closing backtick fences to match:

return text.replace(/```(?:\w+)?\n?([\s\S]*?)```/g, "$1").trim();

When the LLM returns a very long JSON response wrapped in ```json ``` that gets truncated (no closing fence arrives), the regex does not match. The raw text — starting with ```json — is passed directly to JSON.parse, causing a crash.

---

Error

Failed to parse memory actions from LLM response: ```json
{
  "memory": [
    ...
    {
      "id": SyntaxError: Unexpected token '`', "```json
{
"... is not valid JSON
    at JSON.parse (<anonymous>)
    at _Memory.addToVectorStore (mem0ai/src/oss/src/memory/index.ts:370:28)
    at _Memory.add (mem0ai/src/oss/src/memory/index.ts:243:31)
    at OSSProvider.add (index.ts:263:20)

---

Steps to Reproduce

1. Use mem0ai with a LLM that wraps JSON responses in markdown code blocks
2. Trigger a memory add operation where the LLM response is long enough to be truncated before the closing ``` (e.g., agent replies containing large code blocks or architecture documents in the same conversation)
3. Observe Failed to parse memory actions from LLM response in logs

---

Root Cause

The regex /```(?:\w+)?\n?([\s\S]*?)```/g is non-greedy and requires a closing ``` to capture the inner content. A truncated response only has the opening fence — the regex silently skips it and returns the original text unchanged, which still starts with ```json.

---

Suggested Fix

function removeCodeBlocks(text) {
  // Handle complete code blocks (opening + closing fence)
  let result = text.replace(/```(?:\w+)?\n?([\s\S]*?)```/g, "$1").trim();
  // Handle truncated responses where closing ``` never arrives
  result = result.replace(/^```(?:\w+)?\n?/, "").replace(/\n?```$/, "").trim();
  return result;
}

This is a two-pass approach:

• First pass: strips complete ```lang ... ``` blocks (existing behavior)
• Second pass: strips any remaining leading/trailing fence markers (handles truncation)

---

Environment

Field	Value
mem0ai version	0.3.3 (npm)
LLM	claude-haiku-4-5 via LiteLLM proxy
Affected function	removeCodeBlocks in dist/oss/index.js line ~2648
Affected callers	addToVectorStore (line ~4764), updateMemory (line ~4804)

---

Notes

• The removeCodeBlocks function is already used in the right places — only the implementation needs to be updated
• This fix is backwards-compatible and does not affect responses that are already clean JSON
• Workaround applied locally by patching dist/oss/index.js directly

[Jah-yee]

I have submitted PR #4415 which fixes this issue. The fix adds a second pass to strip any remaining leading/trailing fence markers when the closing fence is missing due to truncation.