fix(workflows): preserve valid empty strings during import

[BillLeoutsakosvl346]

Workflow import converted every empty subblock string to null, losing cleared text and explicit empty dropdown choices. Preserve empty strings for scalar string-valued controls and declared single-select empty choices, using the repaired field type. Multi-select fields retain legacy blank-to-null normalization and preserve valid empty arrays; invalid dropdown blanks still allow configured defaults.

Validation: 42 focused import/roundtrip/sanitization tests pass (5 regression cases added), app typecheck passes, changed-file Biome and API validation pass. The roundtrip regression fails on staging with null instead of ''. Browser import/export passed with a synthetic three-block workflow: exported cleared code and sandbox selection stayed '', explicit language stayed null, and input-format stayed []. Running the imported workflow succeeded and displayed '', null, 0, and false unchanged in its output.

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1 Skipped Deployment

Project	Deployment	Actions	Updated
docs	Skipped		Sep 9, 2026 1:37am UTC

[greptile-apps]

Confidence Score: 4/5

The PR should not merge until empty strings on multi-select selectors continue to normalize rather than being preserved as scalar values.

Findings

1.  Multi-select blanks stay scalar ▶

Summary

• Resolves malformed subblocks using their configured field type.
• Preserves empty strings for recognized string-valued controls and selectors.
• Adds import round-trip and focused sanitization regression coverage.
• The selector classification needs to distinguish single-select from array-valued multi-select fields.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart TD
  A[Imported subblock value is empty string] --> B[Repair metadata from block config]
  B --> C{Control accepts empty string?}
  C -->|Text-like or declared empty single-select| D[Preserve empty string]
  C -->|Non-string or invalid dropdown blank| E[Normalize to null]
  C -->|Current blanket selector branch| F[Multi-select selector incorrectly preserves scalar empty string]

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[greptile-apps]

Multi-select blanks stay scalar

Multi-select selectors store arrays, but this condition treats every selector as accepting an empty string. When an imported workflow contains a legacy '' for a multi-select selector such as departmentIds, folderSelection, or channelFilter, sanitization preserves that scalar instead of normalizing it, leaving the field with a value that conflicts with its array contract. Exclude multi-select selectors from empty-string preservation.

Suggested change

	if (EMPTY_STRING_TYPES.has(type) || type.endsWith('-selector')) return true
	if (EMPTY_STRING_TYPES.has(type) || (type.endsWith('-selector') && !config?.multiSelect)) return true