```plaintext
%% Observability Stack Architecture (ADR-0025)
%% C4 Component diagram showing telemetry flow

flowchart TB
    subgraph apps["📦 Applications"]
        direction LR
        go["Go Apps<br/>(OTEL SDK)"]
        python["Python Apps<br/>(OTEL SDK)"]
        node["Node.js Apps<br/>(OTEL SDK)"]
        java["Java Apps<br/>(OTEL SDK)"]
    end

    subgraph collection["📡 Telemetry Collection"]
        otel["OpenTelemetry<br/>Collector<br/>━━━━━━━━<br/>OTLP gRPC :4317<br/>OTLP HTTP :4318"]
    end

    subgraph storage["💾 Storage Layer"]
        direction LR
        
        subgraph metrics_store["Metrics"]
            prometheus["📊 Prometheus<br/>14d retention<br/>50GB"]
        end

        subgraph logs_traces["Logs & Traces"]
            clickstack["📋 ClickStack<br/>(ClickHouse)"]
        end
    end

    subgraph visualization["📈 Visualization"]
        grafana["🎨 Grafana<br/>Dashboards<br/>& Exploration"]
    end

    subgraph alerting["🔔 Alerting Pipeline"]
        alertmanager["⚠️ Alertmanager"]
        ntfy["📱 ntfy<br/>(Push)"]
        discord["💬 Discord"]
    end

    %% App to collector
    go -->|"OTLP"| otel
    python -->|"OTLP"| otel
    node -->|"OTLP"| otel
    java -->|"OTLP"| otel

    %% Collector to storage
    otel -->|"Metrics"| prometheus
    otel -->|"Logs"| clickstack
    otel -->|"Traces"| clickstack

    %% Storage to visualization
    prometheus --> grafana
    clickstack --> grafana

    %% Alerting flow
    prometheus -->|"PrometheusRules"| alertmanager
    alertmanager --> ntfy
    ntfy --> discord

    classDef app fill:#3498db,color:white
    classDef otel fill:#e74c3c,color:white
    classDef storage fill:#27ae60,color:white
    classDef viz fill:#9b59b6,color:white
    classDef alert fill:#f39c12,color:black

    class go,python,node,java app
    class otel otel
    class prometheus,clickstack storage
    class grafana viz
    class alertmanager,ntfy,discord alert

```