ADR-006: Exit Code Behavior

Status: Accepted

Context: CI pipelines need clear pass/fail signals.

Decision: Exit 0 if no findings meet the threshold. Exit 1 if any finding at or above the threshold. Exit 2 for usage/file errors. Default threshold is HIGH. Configurable via --fail-on.

Rationale: - Matches Hadolint's --failure-threshold and KICS's severity-mapped exit codes. - Default behavior is strict (fail on high/critical) but teams can relax with --fail-on critical or tighten with --fail-on low. - Exit 2 for file/config errors distinguishes "your compose file has issues" from "compose-lint itself couldn't run." - A rule that raises is isolated rather than aborting the run (the failure is reported to stderr and the sweep continues), and maps to exit 2 for the same reason: it means compose-lint itself couldn't complete the analysis, not that the file failed the lint. This keeps a crash from being silently truncated mid-sweep or mistaken for a clean exit-1 findings result.