Return the sorted, de-duplicated list of variable names the target's Postman or Bruno collection reads — from {{placeholder}} references in URLs, headers, bodies and auth blocks, and from pm.environment.get('name') / bru.getVar('name') / bru.getEnvVar('name') calls in pre-request and test scripts. Setter calls are intentionally excluded; globals-scope getters (pm.globals.get / bru.getGlobalEnvVar) are also excluded because the engine only seeds env-scope, so surfacing them would produce silent misses at scan time.

Only Postman/Bruno targets are supported; other schema types return 400. Malformed per-entry Bruno YAML is skipped so a collection accepted at upload time still yields a usable dropdown.