Sepsis bundle — antibiotics never go in before the blood cultures are

sepsis_bundle.cell

// ============================================================================
// SEPSIS BUNDLE — antibiotics never go in before the blood cultures are
// drawn, and the 1-hour clock is real
// ============================================================================
//
// The Surviving Sepsis "hour-1 bundle" saves lives by ordering: measure
// lactate, DRAW BLOOD CULTURES, then give broad-spectrum antibiotics, then
// start fluids — all within an hour of recognition. The ordering is not
// bureaucratic: give antibiotics before the cultures are drawn and you
// sterilize the sample, losing the chance to identify the organism and
// target therapy. The other failure is the clock: every minute of delay to
// antibiotics raises mortality.
//
// Here the bundle is a state machine where `antibiotics` is reachable ONLY
// after `cultures_drawn` — there is no edge that lets the drug precede the
// draw. A memory invariant pins elapsed minutes into [0,60]: a bundle
// charted as completed past the hour is a rejected write, so "we'll call it
// on-time" cannot be recorded. `completed` is terminal.
//
//   soma verify examples/corpus/medical/sepsis_bundle.cell
//   soma test   examples/corpus/medical/sepsis_bundle.cell
//   soma run    examples/corpus/medical/sepsis_bundle.cell demo
// ============================================================================

cell SepsisBundle {
    face {
        signal recognize(case_id: String) -> Map
        signal lactate(case_id: String) -> Map
        signal cultures(case_id: String) -> Map
        signal antibiotics(case_id: String, minute: Int) -> Map
        signal fluids(case_id: String) -> Map
        signal complete(case_id: String) -> Map
        signal bundle_state(case_id: String) -> String
        signal demo() -> String
    }

    memory {
        // Minute (0..60) at which antibiotics were given, relative to
        // recognition. The hour-1 target is the wall: charting a time past
        // 60 is a rejected write — you cannot record a late dose as if it
        // counted.
        abx_minute: Map<String, Int> [persistent, consistent]
        invariant abx_minute >= 0 && abx_minute <= 60
    }

    // The bundle order, made structural. `antibiotics` is unreachable
    // until `cultures_drawn` — the draw always precedes the drug.
    // `completed` is terminal.
    state bundle {
        initial: recognized
        recognized      -> lactate_measured
        lactate_measured -> cultures_drawn
        cultures_drawn  -> abx_given          // ONLY after the draw
        abx_given       -> fluids_started
        fluids_started  -> completed          // terminal
    }

    on recognize(case_id: String) {
        return map("ok", true, "state", get_status(case_id))
    }

    on lactate(case_id: String) {
        let r = try { transition(case_id, "lactate_measured") }
        if r.error != () { return map("ok", false, "reason", "{r.error}") }
        return map("ok", true, "state", get_status(case_id))
    }

    on cultures(case_id: String) {
        let r = try { transition(case_id, "cultures_drawn") }
        if r.error != () { return map("ok", false, "reason", "{r.error}") }
        return map("ok", true, "state", get_status(case_id))
    }

    // Antibiotics — refused before cultures are drawn (the machine raises),
    // and the time is pinned inside the hour by the invariant.
    on antibiotics(case_id: String, minute: Int) {
        let st = get_status(case_id)
        if st != "cultures_drawn" {
            return map("ok", false, "reason",
                "antibiotics before cultures would sterilize the sample (state {st})")
        }
        let w = try { abx_minute.set(case_id, minute) }
        if w.error != () {
            return map("ok", false, "reason", "past the hour-1 window: {w.error}")
        }
        transition(case_id, "abx_given")
        return map("ok", true, "minute", minute, "state", get_status(case_id))
    }

    on fluids(case_id: String) {
        let r = try { transition(case_id, "fluids_started") }
        if r.error != () { return map("ok", false, "reason", "{r.error}") }
        return map("ok", true, "state", get_status(case_id))
    }

    on complete(case_id: String) {
        let r = try { transition(case_id, "completed") }
        if r.error != () { return map("ok", false, "reason", "{r.error}") }
        return map("ok", true, "state", get_status(case_id))
    }

    on bundle_state(case_id: String) { return get_status(case_id) }

    on demo() {
        recognize("c-1")
        lactate("c-1")
        // the slip: try antibiotics before drawing cultures — REFUSED
        let early = antibiotics("c-1", 20)
        cultures("c-1")
        antibiotics("c-1", 35)
        fluids("c-1")
        complete("c-1")
        let st = bundle_state("c-1")
        print("abx before cultures: {early}")
        print("final state:         {st}")
        return "demo done"
    }
}

cell test SepsisTests {
    rules {
        assert recognize("a").ok == true
        assert lactate("a").ok == true

        // antibiotics cannot precede the culture draw
        assert antibiotics("a", 10).ok == false
        assert_fails transition("a", "abx_given")

        // correct order: draw, then give within the hour
        assert cultures("a").ok == true
        assert antibiotics("a", 40).ok == true
        assert fluids("a").ok == true
        assert complete("a").ok == true
        assert bundle_state("a") == "completed"

        // completed is terminal
        assert_fails transition("a", "abx_given")

        // the clock invariant refuses a dose charted past the hour
        assert recognize("b").ok == true
        assert lactate("b").ok == true
        assert cultures("b").ok == true
        assert antibiotics("b", 90).ok == false    // 90 > 60 — refused
        assert_fails abx_minute.set("b", 61)
    }
}