Error using PruningContentFilter in Playground: "Nested function calls are not permitted"

[TizianoSciarpetta]

Hi everyone,

I'm encountering an issue while trying to use the following configuration in the Playground:

CrawlerRunConfig(
cache_mode=CacheMode.BYPASS,
markdown_generator=DefaultMarkdownGenerator(
content_filter=PruningContentFilter(
threshold=0.4,
threshold_type="fixed"
)
)
)

When running this setup, I consistently receive the following error:

{
"error": "{"detail":"Nested function calls are not permitted"}"
}

From the error message, it seems like the problem might be related to how the configuration is being interpreted or executed internally—possibly due to nested calls within the markdown_generator or content_filter.

Has anyone experienced a similar issue or knows if this configuration is currently unsupported in the Playground environment? Any guidance or workaround would be greatly appreciated.

Thanks in advance!

[SohamKukreti]

Hi! You’re reading the error correctly, this is expected behavior in the Playground right now.

For security hardening, we explicitly disabled nested function calls in Playground config parsing, so expressions like:

CrawlerRunConfig(markdown_generator=DefaultMarkdownGenerator(content_filter=PruningContentFilter(...)))

are blocked and return:

Nested function calls are not permitted.

In deploy/docker/server.py, _safe_eval_config() walks the AST and rejects any nested ast.Call:

• if isinstance(node, ast.Call) and node is not call:
• raise ValueError("Nested function calls are not permitted")

This restriction was introduced in security commit:

• 2fc39cb — fix(security): remove eval() from computed fields, harden config deserializer
• Commit message explicitly mentions hardening _safe_eval_config and blocking risky constructs.

So yes, this pattern is currently unsupported in Playground by design (security reasons), not a bug in your specific config. The config should work normally.
Thanks!