Make it impossible to make a reference to a link that does not exist

[konard]

Summary

• Implement validation to prevent references to non-existent links in query operations
• Allow references to link IDs that will become available after the current operation
• Add comprehensive test coverage for the validation functionality

Changes Made

• Added ValidateLinksExistOrWillBeCreated function to check link references
• Collect all link IDs that will be created in substitution patterns
• Validate that references in both restriction and substitution patterns are valid
• Support for mutual references between links created in same operation
• Proper handling of variables ($var), wildcards (*), and definitions vs references

Test Coverage

• Test for invalid reference to non-existent link (should throw exception)
• Test for valid self-references (should succeed)
• Test for mutual cross-references in same operation (should succeed)
• Test for references to existing links (should succeed)
• Test for update operations with invalid references (should throw exception)
• Test that variables and wildcards are not validated (should succeed)

Example Behaviors

❌ Invalid (now prevented):

clink '() ((1: 10 20))' # Links 10 and 20 don't exist and won't be created

✅ Valid (still allowed):

clink '() ((1: 1 2) (2: 2 1))' # Both links created in same operation
clink '() ((1: 1 1))'          # Self-reference
clink '(() ((1: $var *)))'     # Variables and wildcards

🤖 Generated with Claude Code

Co-Authored-By: Claude [email protected]

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Resolves #15