chore(stpa): migrate 501 shorthand link fields to canonical blocks — rivet validate PASS

[avrabe]

Summary

rivet validate on main: FAIL (625 errors, 174 warnings, 0 broken cross-refs).
This PR: PASS (91 warnings) — all 625 cardinality ERRORs resolved.

Root cause

Rivet's schema declares link-fields for STPA types (e.g. uca.controller → issued-by, uca.hazards → leads-to-hazard). Authors used the shorthand form at the top level of each artifact:

- id: UCA-1
  type: uca
  controller: CTRL-PARSER
  hazards: [H-5]

Rivet's stpa-yaml source format does not expand shorthand into the links: graph, so every artifact's link-counter reported "requires N targets, found 0" despite the cross-refs resolving fine (hence the 0 broken cross-refs paradox).

Upstream fix tracked at pulseengine/rivet#154.

What this PR does

• Adds a canonical links: block to 501 artifacts across 4 of 8 STPA YAML files, derived from their existing shorthand fields.
• Preserves the shorthand fields (authors keep writing them; stpa-yaml keeps accepting them).
• Fixes 6 type: safety-requirement artifacts in rendering-analysis.yaml to type: requirement — that type isn't declared in any loaded schema.

Insertions per file:

File	Links added
safety/stpa/analysis.yaml	185
safety/stpa/solver-analysis.yaml	201
safety/stpa/security.yaml	106
safety/stpa/rendering-analysis.yaml	9
(requirements, architecture, validation, solver-requirements: unchanged)	0

Migration driver

scripts/stpa_migrate_links.py — text-based line transformer. Preserves all comments and formatting; only inserts new lines after each type: line.

Mapping table hardcoded from AS-5506D §4-§11 + rivet's stpa schema:

hazard.losses              → leads-to-loss
sub-hazard.parent          → refines
system-constraint.hazards  → prevents
uca.controller             → issued-by
uca.hazards                → leads-to-hazard
controller-constraint.controller → constrains-controller
controller-constraint.ucas → inverts-uca
controller-constraint.hazards → prevents
loss-scenario.uca / .ucas  → caused-by-uca
loss-scenario.hazards      → leads-to-hazard
control-action.source      → issued-by
control-action.target      → acts-on

Test plan

• rivet validate goes FAIL → PASS.
• Zero broken cross-refs before and after (invariant preserved).
• Diff verified — no deletions, pure additive insertions (except the 6 safety-requirement → requirement type corrections).
• Re-running the script on already-migrated files is idempotent (detects existing links: blocks and skips).

Not in this PR

• The 91 remaining warnings are traceability coverage gaps (e.g. "UCA should be addressed by at least one controller constraint"). Coverage gaps — real, but separate work.
• The 976 INFO-level schema-drift messages (fields like method, traces-to, mitigates not declared in schema) are unaffected by this migration. Fix requires either upstream rivet schema updates or further artifact rewriting — tracked at rivet#154.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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