digraph lifecycle {
    rankdir=TB
    bgcolor="#0a0e17"
    fontname="Helvetica"
    node [fontname="Helvetica" fontsize=11 style=filled color="#1e2a4a" fontcolor="#e8eaf0"]
    edge [fontname="Helvetica" fontsize=9 fontcolor="#8892a8" color="#4a5568"]

    label="Lambda execution environment lifecycle"
    labelloc=t
    fontsize=16
    fontcolor="#0066ff"

    subgraph cluster_cold {
        label="Cold start (first invocation on a fresh execution environment)"
        style=dashed
        color="#ff3d00"
        fontcolor="#ff3d00"

        download [label="1. Download code\nzip / container layers" fillcolor="#243056" shape=box]
        bootstrap [label="2. Start runtime\nbootstrap (python3.x)" fillcolor="#243056" shape=box]
        init [label="3. Init phase\nrun module-level code\nimport boto3 / aioboto3\nbuild clients\n(billed; capped at 10 s)" fillcolor="#1a1a3a" shape=box fontcolor="#ffc107"]
    }

    subgraph cluster_invoke {
        label="Invocation"
        style=dashed
        color="#1e2a4a"
        fontcolor="#8892a8"

        handler [label="handler(event, context)\nyour code runs\n(billed)" fillcolor="#0d1a33" shape=box]
        respond [label="return / raise" fillcolor="#121829" shape=box]
    }

    subgraph cluster_warm {
        label="Warm reuse (subsequent invocations on the same environment)"
        style=dashed
        color="#00c853"
        fontcolor="#00c853"

        thaw [label="thaw\n(microseconds)" fillcolor="#1a3a1a" shape=box]
        reuse [label="globals retained:\nclients, /tmp,\nin-memory caches" fillcolor="#1a3a1a" shape=note fontcolor="#00c853"]
    }

    freeze [label="freeze\nprocess paused\n(after handler returns)" fillcolor="#121829" shape=box]
    shutdown [label="shutdown\nidle ~5–15 min →\nenv torn down\n/tmp gone" fillcolor="#121829" shape=box fontcolor="#ff3d00"]

    download -> bootstrap
    bootstrap -> init
    init -> handler [label="event arrives" color="#0066ff"]
    handler -> respond
    respond -> freeze

    freeze -> thaw [label="next event" color="#00c853"]
    thaw -> handler [label="reuse env" color="#00c853"]
    reuse -> handler [style=dotted color="#00c853"]

    freeze -> shutdown [label="idle too long" style=dashed color="#ff3d00"]
}