docs: document factory pattern for model reuse (#650)

[stack72]

Summary

• Add Scenario 5: Factory Pattern for Model Reuse to swamp-model/references/scenarios.md — covers when to use factory vs separate models, model definition with inputs schema, the name ↔ data name connection, create/delete workflow snippets, and input requirements for delete
• Add Factory Model Patterns section to swamp-workflow/references/data-chaining.md — covers calling one model multiple times, referencing factory instance data downstream, and delete step requirements with before/after examples
• Add brief pointer in swamp-model/SKILL.md after the Model Inputs Schema section

Key insight documented: globalArgument expressions are selectively evaluated — inputs not provided are skipped, and a runtime error only occurs if the method code actually tries to access an unresolved globalArgument. Delete steps always need instanceName (to key the data instance) but other create-time inputs are only required if the delete method implementation accesses them.

Closes #650

Test plan

• Documentation-only change, no code modified
• Verified all anchor links resolve within the files
• Verified line counts stay reasonable (SKILL.md: 550 lines)

🤖 Generated with Claude Code

[github-actions]

Adversarial Review

Critical / High

None.

Medium

None.

Low

None.

Verdict

PASS — This PR contains only documentation changes (Markdown skill reference files). No executable code is modified. The internal cross-references between the skill files are correctly formed. The YAML examples in the documentation are illustrative and consistent with the documented patterns elsewhere in the skill files.

No security, logic, error handling, concurrency, or resource management issues can exist in documentation-only changes.

[github-actions]

Review Summary

This is a well-structured documentation-only PR that adds the Factory Pattern for Model Reuse scenario to the swamp-model and swamp-workflow skills. The content closes #650.

Blocking Issues

None - This PR is ready to merge.

Analysis

Code Style (N/A - Documentation Only)

• No TypeScript code changes, so no strict mode or type violations
• No any types introduced
• No unit tests required for documentation

Content Quality

• Clear decision tree for when to use factory vs separate models
• Comprehensive YAML examples for create and delete workflows
• Well-documented explanation of the instanceName → name globalArgument → data instance keying relationship
• Helpful tables summarizing input requirements and CEL paths
• Key insight about selective evaluation of globalArguments is clearly explained

Cross-References

• SKILL.md:173-175 correctly references references/scenarios.md#scenario-5-factory-pattern-for-model-reuse
• data-chaining.md correctly references ../../swamp-model/references/scenarios.md#scenario-5-factory-pattern-for-model-reuse
• Both relative paths resolve correctly given the skill directory structure

Domain-Driven Design

Documentation aligns with DDD principles:

• Clear separation between model definition (template) and data instances (identities)
• The factory pattern uses instanceName as the identity key, properly explained
• Lifecycle documentation (create/delete) is consistent and thorough

Suggestions (Non-blocking)

1. Minor: The delete workflow example includes all inputs (cidrBlock, availabilityZone) even though the text explains they may be optional. This is actually good for completeness, and the table below clearly explains what's required vs optional.

LGTM - well-documented pattern that will help users understand model reuse!