agent couldn't parse W&B run config YAML and failed with a config parse error

TL;DR

Parse the config as the YAML it is, with attention to how W and B writes it: run configs include typed values, nested structures, and sometimes anchors or custom formatting that a naive loader or a regex scraper mangles. Load with a full YAML parser, inspect the failing document around the reported line, and normalise typed wrappers, such as value objects, before reading fields.

agent couldn't parse W&B run config YAML and failed with a config parse error

Use this when

• The run or call fails with this symptom: agent could not parse a W and B run config YAML and failed with a config parse error.
• You are working on an agent reading W and B run configs exported as YAML and the failure repeats on the same run or configuration.
• You need the failing run, call, or stage isolated before changing code or thresholds.

Not for this skill when

• A config file that is genuinely malformed from a hand edit, where the fix is correcting the file rather than the parser.
• The error text names a different tool, stage, or root cause. Match the verbatim error first and use that skill.

Steps

1. Load the file with a standard YAML parser and capture the exact line and column of the parse failure. Verify: the failure location is known
2. Inspect that region for the usual W and B shapes: nested value objects, anchors, or unquoted strings containing colons. Verify: the offending construct is identified
3. Parse through a normalisation step that unwraps typed value objects into plain scalars after loading. Verify: the config loads into plain fields
4. Validate the parsed result by checking the fields the agent needs exist with expected types before use. Verify: required fields are present and typed correctly

Variant phrasings

agent could not parse wandb run config yaml

The verbatim phrasing.

wandb config yaml parse error agent value objects

The value-object phrasing.

agent failed reading run config yaml anchors fix

The anchors phrasing.

Compatibility: Agent parsers reading Weights and Biases run config files in YAML

Why it happens

Run configs are written for the tracker's own reader, not for generic tools, so they use the corners of YAML that simple parsers and hand-rolled splitting handle badly. The parse error is a format mismatch between writer and reader, not corrupt data.

Edge cases / pitfalls

• Prefer the tracker's API or its own export for config data when available; files are the fallback, not the interface.
• A config with duplicate keys loads differently across parsers; check for duplicates if values look wrong after a clean parse.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_uQeCIgV2QUA76pe3Z3zfEA