fix(converter): don't let trailing braces corrupt valid JSON extraction

[ErenAta16]

_JSON_PATTERN = re.compile(r"({.*})", re.DOTALL) in converter.py greedily matches from the first { to the last } anywhere in the string. If the LLM's output contains a complete, valid JSON object followed by commentary that itself references curly braces - mentioning the schema, a code snippet, a set literal, anything - the match swallows that trailing text too, and json.loads fails on the resulting garbage even though the actual JSON object was perfectly well formed:

result = '''Here is the extracted data:
{"name": "Alice", "age": 30}

Note: this response follows the requested schema (see the format described as {"type": "object"} in the task).'''

match = _JSON_PATTERN.search(result)
json.loads(match.group())
# json.decoder.JSONDecodeError: Extra data: line 3 column 1 (char 30)

In handle_partial_json, that JSONDecodeError triggers an immediate fall through to convert_with_instructions (a re-prompt), discarding output that was already correct.

This is a different failure mode from #5460 (closed via #5461), which was about the regex false-positively matching brace-delimited text that isn't JSON at all (e.g. GraphQL schemas). This one is a false-negative: genuinely valid JSON gets corrupted because of what comes after it.

Fix

Replaced the regex-based extraction with json.JSONDecoder(strict=False).raw_decode(result, start), starting at the first {. raw_decode parses exactly one JSON value and stops there, so trailing braces elsewhere in the string can't corrupt an otherwise-valid match. The GraphQL fall-through from #5461 is preserved, since raw_decode still raises JSONDecodeError on non-JSON brace-delimited content for the same reason json.loads did.

Applied to both handle_partial_json and async_handle_partial_json, which shared the identical pattern. Also drops the now-unused re import and the _JSON_PATTERN constant.

Testing

Added test_handle_partial_json_ignores_braces_in_trailing_commentary to tests/utilities/test_converter.py, covering the exact repro above.

Ran the full tests/utilities/test_converter.py suite: 51/52 passing. The one failure (test_supports_function_calling_false) is pre-existing and unrelated - it needs the optional litellm package, which isn't installed in my sandbox, and I confirmed it fails identically on unpatched main before making any changes.

I did try a second test with brace-containing text on both sides of the target object, expecting it to also resolve correctly - it doesn't, because raw_decode starting at the first { will happily parse an earlier, self-contained JSON-looking object if one exists before the real one. That's a real limitation, but a different (arguably harder - which object is "the" answer?) problem than what this PR fixes, so I removed that test rather than either overclaiming or scope-creeping the fix. Happy to discuss if that's worth a follow-up.

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📝 Walkthrough

Walkthrough

Changes

Partial JSON Parsing

Layer / File(s)	Summary
Deterministic JSON extraction lib/crewai/src/crewai/utilities/converter.py	Replaces regex-based extraction with a helper that finds the first { and decodes one JSON value using JSONDecoder.raw_decode.
Sync and async partial JSON integration lib/crewai/src/crewai/utilities/converter.py, lib/crewai/tests/utilities/test_converter.py	Updates both handlers to use the helper and adds synchronous and asynchronous coverage for braces in trailing commentary.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: fixing JSON extraction when trailing braces appear in commentary.
Description check	✅ Passed	The description is directly about the converter JSON extraction bug and the implemented fix, so it matches the changeset.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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[coderabbitai]

🧹 Nitpick comments (1)

lib/crewai/tests/utilities/test_converter.py (1)

228-242: 📐 Maintainability & Code Quality | 🔵 Trivial | 💤 Low value

Consider adding an async equivalent test.

Both handle_partial_json and async_handle_partial_json now share _extract_first_json_object, so the extraction logic is covered. However, there's no async test for the trailing-commentary scenario. Adding one would provide symmetric coverage for the async path, which the PR objectives explicitly mention.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@lib/crewai/tests/utilities/test_converter.py` around lines 228 - 242, Add an
async counterpart to
test_handle_partial_json_ignores_braces_in_trailing_commentary, using the same
JSON input with brace-containing trailing commentary and awaiting
async_handle_partial_json. Assert the returned value is a SimpleModel with the
expected name and age to provide equivalent coverage for the async path.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@lib/crewai/tests/utilities/test_converter.py`:
- Around line 228-242: Add an async counterpart to
test_handle_partial_json_ignores_braces_in_trailing_commentary, using the same
JSON input with brace-containing trailing commentary and awaiting
async_handle_partial_json. Assert the returned value is a SimpleModel with the
expected name and age to provide equivalent coverage for the async path.

---

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• lib/crewai/src/crewai/utilities/converter.py
• lib/crewai/tests/utilities/test_converter.py

[ErenAta16]

Fair point - added test_async_handle_partial_json_ignores_braces_in_trailing_commentary alongside the sync one, since both paths share _extract_first_json_object. Full suite still at 52/53 (same pre-existing unrelated litellm-dependency failure as before).