Ghost Bugs Awakened: How Call Graph Shifts Expose Hidden Defects

CI failures often surface pre-existing bugs rather than new regressions, but distinguishing between them requires recognizing that call graph changes—not code changes—are the true diagnostic variable. Understanding this pattern prevents developers from misattributing existing defects to recent changes and avoids unnecessary rollbacks. This insight is particularly valuable in complex systems where code path routing can expose masked vulnerabilities in async/sync implementations or platform-specific edge cases.