Fix tooltip _position migration writes invalid empty string

[swashbuck]

Subject of the issue

The _tooltip._position migration writes an empty string '', which is not a valid value for the _position enum in the schema. Any course migrated through this step then fails modern-schema validation (for example when imported into the authoring tool). The bug is present on master (6.20.1).

Your environment

• Framework 5.56.2, adapt-contrib-hotgraphic 6.20.1 (also present on master)
• N/A (build-time migration, not browser)

Steps to reproduce

1. Take a hotgraphic course authored before v6.13.1 (no _tooltip._position on items).
2. Migrate it up through v6.13.1 (e.g. grunt migration:test --file=adapt-contrib-hotgraphic, or import into the authoring tool).
3. Validate the migrated content against the current component schema.

Expected behaviour

After migration, each item's _tooltip._position should hold the schema default "bottom" (a valid enum value), so the content validates.

Actual behaviour

The v6.12.1 > v6.13.1 migration sets _tooltip._position to ''. _position was introduced in v6.13.1 already carrying an enum and a "bottom" default; '' is not a permitted value, so validation fails, e.g.:

/_items/0/_tooltip/_position must be equal to one of the allowed values

The migration's own checkContent passes only because it asserts the same invalid ''.

Suggested Fix (if known)

In migrations/v6.js, set _tooltip._position to the schema default 'bottom' in both the mutateContent ("add item _tooltip._position attribute") and the matching checkContent.

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Posted via collaboration with Claude Code

[swashbuck]

Additional context for reviewers on why this has gone unnoticed: at runtime hotgraphicModel.js does

tooltipConfig._position = tooltipConfig._position || 'outside bottom middle middle';

so an empty-string _position is falsy and silently falls back to a default. The empty string is therefore harmless at runtime, which is why courses migrated through this step have run fine. It only surfaces when the migrated content is validated against the modern component schema (e.g. on authoring-tool import), where '' is not a member of the _position enum.

Setting the migration value to the schema default 'bottom' makes migrated content identical to content authored fresh against the current schema (where Ajv applies the 'bottom' default), so this is preferable to widening the enum to accept ''.

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Posted via collaboration with Claude Code