Is this a new bug in dbt-core?

• I believe this is a new bug in dbt-core
• I have searched the existing issues, and I could not find an existing issue for this bug

Current Behavior

Fusion has a new configuration named static_analysis: https://docs.getdbt.com/docs/fusion/new-concepts#configuring-static_analysis

This is an Enum value in Fusion, with potential values on | off | unsafe

dbt Core respects this as a top-level configuration, but it doesn't do any more detailed type validation.

There is therefore a distinction between:

models:
  - name: my_model
    config:
      static_analysis: 'off'

and:

models:
  - name: my_model
    config:
      static_analysis: off

Can you spot the difference?

• The first one will serialize to manifest.json with "static_analysis": "off"
• The second one will serialize to manifest.json with "static_analysis": false

Why? Because yaml interprets off as falsy:

• https://stackoverflow.com/questions/42283732/are-on-and-off-supposed-to-be-interpreted-as-true-or-false-in-yaml-1-2
• https://yaml.org/type/bool.html

This leads to an error if/when Fusion tries to deserialize a manifest.json (v12) produced by dbt Core, as for deferral / state:modified -

error: dbt1013: YAML error: invalid type: boolean `false`, expected a Value::Tagged enum
  --> state/manifest.json
  Finished 'compile'  with 1 error in 3s 274ms

Expected Behavior

dbt Core serializes static_analysis to manifest.json as a string, not a boolean

Steps To Reproduce

-- models/my_model.sql
select 1 as id

models:
  - name: my_model
    config:
      static_analysis: off

dbt parse → examine manifest.json, or:

% dbt ls -s my_model --output json --output-keys config -q | jq .config.static_analysis
false

Relevant log output

Environment

- OS: macOS 15.6.1
- Python: 3.9.6
- dbt: 1.10.11

Which database adapter are you using with dbt?

No response

Additional Context

Users can switch static_analysis: off to static_analysis: 'off' to work around this issue in the meantime