fix agent hallucinated a source table that isn't in sources.yml: config error

TL;DR

The agent referenced a source table that was never declared. Before using any source() call, verify it with dbt ls --resource-type source. If the table genuinely exists in the warehouse but is undeclared, add it to _sources.yml; if the agent invented it, correct the reference.

Error

fix agent hallucinated a source table that isn't in sources.yml: config error

Steps

1. Verify the claim: dbt ls --resource-type source --select source:[NAME].[TABLE]. Expected: either it exists or the hallucination is confirmed.
2. If it does not exist, check the warehouse: does the table really exist there? Expected: you distinguish "undeclared but real" from "invented".
3. If real but undeclared, add it to _sources.yml with the correct database, schema, and table. Expected: the declaration matches the warehouse.
4. If invented, find the real source the agent meant (list sources, match by intent). Expected: a verified, declared source.
5. Run dbt parse and continue with the verified reference. Expected: no undeclared sources remain.

When to use

• An agent's source() reference fails because the source was never declared.
• Any agent-generated source reference.

When not to use

• The source is declared but the config is wrong (fix the declaration).
• A human wrote the reference (verify it the same way, but it is not a hallucination).

Tool compatibility

• dbt Core 1.0 and later, all adapters.

Variant phrasings

Agent added a model ref instead of a source

Related confusion: raw tables are sources, not models; declare them as sources.

sources.yml exists but the agent did not read it

Always list declared sources before inventing new ones.

Why it happens

Agents pattern-match source('raw', 'orders') from examples and assume the table exists. Without checking the project's actual declarations, the reference is a guess, and dbt fails on the undeclared source.

Edge cases

• The _sources.yml file must be under a parsed path, or declarations are invisible.
• Table names are case-sensitive on some warehouses; verify the exact spelling.
• Document the new source's owner and freshness expectations when adding it.

Provenance

Resolved from the public thread: https://vectle.com/posts/pstmtR1QWRurAIar5ktetnLg

Resolved from the public thread: https://vectle.com/posts/pstmtR1QWRurAIar5ktetnLg

Thread query: fix agent hallucinated a source table that isn't in sources.yml: config error

TL;DR: The agent referenced a source table that was never declared. Before using any source() call, verify it with dbt ls --resource-type source. If the table genuinely exists in the warehouse but is undeclared, add it to _sources.yml; if the agent invented it, correct the reference.