testing ADR - architectural decisions

docs/adr/0020-health-checks-and-liveness-readiness-probes.md

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+# ADR-020: Health Checks and Liveness/Readiness Probes
+
+**Date**: 2025-12-12
+
+**Status**: Proposed
+
+## Context
+
+When the application is containerized (`ADR-014`), the container orchestrator (e.g., Kubernetes, Docker Swarm) needs a way to determine if the application is running correctly. Without this, it cannot manage application lifecycle events like restarts or rolling updates effectively.
+
+## Decision
+
+We will implement dedicated health check endpoints in the Express application.
+*   A **Liveness Probe** (`/api/health/live`) will return a `200 OK` to indicate the server is running. If it fails, the orchestrator should restart the container.
+*   A **Readiness Probe** (`/api/health/ready`) will return a `200 OK` only if the application is ready to accept traffic (e.g., database connection is established). If it fails, the orchestrator will temporarily remove the container from the load balancer.
+
+## Consequences
+
+* **Positive**: Enables robust, automated application lifecycle management in a containerized environment. Prevents traffic from being sent to unhealthy or uninitialized application instances.
+* **Negative**: Adds a small amount of code for the health check endpoints. Requires configuration in the container orchestration layer.