Your app crashed.
Something else caused it.

// Execution layer
(:Trace {id, entry_endpoint})
(:Span  {id, start_ns, end_ns, status})

// Stateful entity layer — the bridge between traces
(:StateEntity   {entity_type: "Order", primary_key: "8812"})
(:StateMutation {seq_no, ts_ns, field, old_val, new_val, lock_held: false})

// Code & Git layer
(:ASTFunction {name, file_path, line_range})
(:GitCommit   {sha, mr_iid})

// Causal edges
(:Span)-[:EXECUTED_FUNCTION]->(:ASTFunction)
(:Span)-[:WROTE_ENTITY {ts_ns, delta_json, tx_isolation}]->(:StateEntity)
(:Span)-[:READ_ENTITY  {ts_ns, snapshot_version}]->(:StateEntity)
(:StateMutation)-[:HAPPENED_BEFORE {delta_ms: 38, concurrent_overlap: true}]->(:StateMutation)

// From the crashing span, hop across shared StateEntity nodes to find
// every OTHER independent trace that mutated the same entity before the crash
MATCH (crash_trace:Trace)-[:HAS_SPAN]->(crash_span:Span {id: $crash_span_id})
MATCH (crash_span)-[r_read:READ_ENTITY|WROTE_ENTITY]->(entity:StateEntity)
MATCH (other_trace:Trace)-[:HAS_SPAN]->(mutator_span:Span)-[r_write:WROTE_ENTITY]->(entity)
WHERE other_trace.id <> crash_trace.id
  AND r_write.ts_ns <= r_read.ts_ns
  AND (r_read.ts_ns - r_write.ts_ns) < 60000000000 // 60s causal window
MATCH (mutator_span)-[:EXECUTED_FUNCTION]->(upstream_fn:ASTFunction)
MATCH (crash_span)-[:EXECUTED_FUNCTION]->(crash_fn:ASTFunction)
RETURN
  entity.primary_key AS collided_entity,
  other_trace.entry_endpoint AS interfering_request,
  other_trace.payload_json AS interfering_payload,
  (r_read.ts_ns - r_write.ts_ns) / 1000000.0 AS race_window_ms,
  r_write.lock_held AS was_locked,
  upstream_fn.file_path AS upstream_mutator_file,
  upstream_fn.name AS upstream_mutator_function,
  crash_fn.name AS downstream_crash_symptom
ORDER BY r_write.ts_ns ASC

// Exact chain of state transitions: entity creation → corrupted read.
// Produces the ordered requests, payloads and ms delays for the replay test.
MATCH (entity:StateEntity {primary_key: "8812"})
MATCH (first:StateMutation {seq_no: 0})-[:MUTATED]->(entity)
MATCH (crash:Span {id: $crash_span_id})
MATCH p = shortestPath((first)-[:HAPPENED_BEFORE|CAUSED_READ*..12]->(crash))
UNWIND nodes(p) AS step
OPTIONAL MATCH (s:Span)-[:EMITTED]->(step)
OPTIONAL MATCH (t:Trace)-[:HAS_SPAN]->(s)
RETURN t.entry_endpoint AS request, t.payload_json AS payload,
       step.field AS field, step.old_val AS old_val, step.new_val AS new_val,
       step.ts_ns / 1000000.0 AS ts_ms
ORDER BY ts_ms ASC

# tests/repro/test_incident_8812.py — generated from graph:incident_8812
import asyncio
import pytest
from tests.repro.harness import Barrier, replay, wallet_credits

@pytest.mark.asyncio
async def test_incident_8812_cross_trace_race(client, worker, seed_order):
    await seed_order(id=8812, status="PENDING", amount=4500)
    barrier = Barrier(parties=3)

    # Causal subgraph: A1 (-38ms) → B2 (-26ms) → C3 (0ms)
    webhook  = replay(client.post, "/webhooks/payment",
                      json={"order_id": 8812, "event": "payment.retry"},
                      barrier=barrier, offset_ms=0)
    expiry   = replay(worker.expire_cart, order_id=8812,
                      barrier=barrier, offset_ms=12)
    checkout = replay(client.post, "/checkout/capture",
                      json={"order_id": 8812}, barrier=barrier, offset_ms=38)

    _, _, res = await asyncio.gather(webhook, expiry, checkout)

    assert res.status_code == 200, res.json()   # RED: 500 InvalidStateError
    assert await wallet_credits(8812) == 1      # no double-credit

  # payments/webhooks.py — upstream mutator, not the crashing line
  def apply_webhook(db, event):
-     order = db.query(Order).get(event.order_id)
+     order = (db.query(Order)
+                .filter_by(id=event.order_id)
+                .with_for_update()            # SELECT ... FOR UPDATE
+                .one())
+     if order.last_event_id == event.id:     # idempotency guard
+         return order
      order.status = transition(order.status, event)
+     order.last_event_id = event.id
      db.commit()

  # graph diff: lock_held false → true · race_condition_reproduced → resolved