Logging your agents, made easy. Without changing them.

Python + OpenAI

1"""A loan-decision agent: one model call, three tools, a clock read, a rule2and a judgment. The model is whatever OPENAI_BASE_URL points at."""3import json4import time5from datetime import datetime, timedelta, timezone6 7import bitexact8from bitexact.adapters import wrap_openai9from openai import OpenAI10 11# The credit bureau's mirror, as of its last nightly sync.12BUREAU_MIRROR = [13    {"applicant_id": "APP-7690", "score": 702, "as_of": "2026-10-30"},14    {"applicant_id": "APP-7713", "score": 512, "as_of": "2026-10-30"},15    {"applicant_id": "APP-7790", "score": 688, "as_of": "2026-10-30"},16]17UNDERWRITER = ("You are an underwriter. Apply the policy exactly. Answer as: "18               "DECISION: <APPROVE|DECLINE|REFER>. REASONS: <codes or none>. "19               "<one sentence>")20 21 22@bitexact.record_tool23def fetch_applicant(applicant_id):24    """The application, as the lending portal holds it."""25    return {"applicant_id": applicant_id, "product": "personal-24",26            "annual_income": 148000, "monthly_debt": 900,27            "requested": 25000, "years_employed": 9}28 29 30@bitexact.record_tool31def pull_credit_report(applicant_id):32    """The applicant's report from the bureau mirror, matched by number."""33    number = int(applicant_id.split("-")[1])34    return min(BUREAU_MIRROR, key=lambda report: abs(35        int(report["applicant_id"].split("-")[1]) - number))36 37 38@bitexact.record_tool39def check_policy(product):40    """The underwriting thresholds for a product."""41    return {"product": product, "min_score": 620, "max_dti": 0.43,42            "version": "4.2"}43 44 45def decide(client, applicant_id):46    received_at = time.time()47    applicant = fetch_applicant(applicant_id)48    report = pull_credit_report(applicant_id)49    policy = check_policy(applicant["product"])50    dti = round(applicant["monthly_debt"] * 12 / applicant["annual_income"], 3)51    reply = client.chat.completions.create(52        model="underwriter-v1",53        messages=[{"role": "system", "content": UNDERWRITER},54                  {"role": "user", "content": json.dumps(55                      {"application": applicant, "credit_report": report,56                       "policy": policy, "dti": dti})}])57    answer = reply.choices[0].message.content58    codes = answer.split("REASONS:")[1].split(".")[0].strip()59    return {"applicant_id": applicant_id,60            "decision": answer.split("DECISION:")[1].split(".")[0].strip().lower(),61            "reasons": [] if codes == "none" else codes.split(", "),62            "explanation": answer.split("REASONS:")[1].split(".", 1)[1].strip(),63            "received_at": received_at}64 65 66def record_outcome(r, result):67    r.record_decision(retention_deadline=(datetime.now(timezone.utc) + timedelta(days=760)).isoformat(),68                      output_flags={"is_adverse_action": result["decision"] == "decline",69                                    "is_automated_decision": True},70                      reason_codes=result["reasons"] or None)71 72 73def main():74    client = OpenAI()75    with bitexact.run("loan-APP-7731", workflow="loan-adjudication",76                      workflow_instance="APP-7731", environment="demo",77                      principal="svc:underwriter") as r:78        client = wrap_openai(client, r)79        result = decide(client, "APP-7731")80        record_outcome(r, result)81    print(json.dumps(result, indent=2))82    return result83 84 85if __name__ == "__main__":86    main()

TypeScript

1// A loan-decision agent: one model call, three tools, a clock read, a rule2// and a judgment. The model is whatever OPENAI_BASE_URL points at.3import { fromEnv, record, recordTool, run, wrapFetch } from "../../../../sdk-ts/src/index.ts";4 5// The credit bureau's mirror, as of its last nightly sync.6const BUREAU_MIRROR = [7  { applicant_id: "APP-7690", score: 702, as_of: "2026-10-30" },8  { applicant_id: "APP-7713", score: 512, as_of: "2026-10-30" },9  { applicant_id: "APP-7790", score: 688, as_of: "2026-10-30" },10];11const UNDERWRITER = "You are an underwriter. Apply the policy exactly. Answer as: "12  + "DECISION: <APPROVE|DECLINE|REFER>. REASONS: <codes or none>. "13  + "<one sentence>";14 15const number = (applicantId: string) => Number(applicantId.split("-")[1]);16 17const tools = {18  /** The application, as the lending portal holds it. */19  fetchApplicant(applicantId: string) {20    return { applicant_id: applicantId, product: "personal-24",21             annual_income: 148000, monthly_debt: 900,22             requested: 25000, years_employed: 9 };23  },24 25  /** The applicant's report from the bureau mirror, matched by number. */26  pullCreditReport(applicantId: string) {27    const distance = (report: { applicant_id: string }) =>28      Math.abs(number(report.applicant_id) - number(applicantId));29    return BUREAU_MIRROR.reduce((best, report) =>30      distance(report) < distance(best) ? report : best);31  },32 33  /** The underwriting thresholds for a product. */34  checkPolicy(product: string) {35    return { product, min_score: 620, max_dti: 0.43, version: "4.2" };36  },37};38tools.fetchApplicant = recordTool("fetch_applicant", tools.fetchApplicant);39tools.pullCreditReport = recordTool("pull_credit_report", tools.pullCreditReport);40tools.checkPolicy = recordTool("check_policy", tools.checkPolicy);41 42async function decide(client: typeof fetch, applicantId: string) {43  const receivedAt = Date.now() / 1000;44  record("nondet", { source: "Date.now() / 1000", value: receivedAt });45  const applicant = tools.fetchApplicant(applicantId);46  const report = tools.pullCreditReport(applicantId);47  const policy = tools.checkPolicy(applicant.product);48  const dti = Math.round(applicant.monthly_debt * 12 / applicant.annual_income * 1000) / 1000;49  const reply = await client(`${process.env.OPENAI_BASE_URL}/chat/completions`, {50    method: "POST",51    headers: { "content-type": "application/json",52               authorization: `Bearer ${process.env.OPENAI_API_KEY}` },53    body: JSON.stringify({54      model: "underwriter-v1",55      messages: [{ role: "system", content: UNDERWRITER },56                 { role: "user", content: JSON.stringify(57                   { application: applicant, credit_report: report, policy, dti }) }],58    }),59  });60  const answer: string = (await reply.json()).choices[0].message.content;61  const reasoned = answer.split("REASONS:")[1];62  const codes = reasoned.split(".")[0].trim();63  return { applicant_id: applicantId,64           decision: answer.split("DECISION:")[1].split(".")[0].trim().toLowerCase(),65           reasons: codes === "none" ? [] : codes.split(", "),66           explanation: reasoned.slice(reasoned.indexOf(".") + 1).trim(),67           received_at: receivedAt };68}69 70function recordOutcome(result: { decision: string, reasons: string[] }) {71  record("decision_record", {72    retention_deadline: new Date(Date.now() + 760 * 86_400_000).toISOString(),73    output_flags: { is_adverse_action: result.decision === "decline",74                    is_automated_decision: true },75    ...(result.reasons.length ? { reason_codes: result.reasons } : {}),76  });77}78 79async function main() {80  let client = fetch;81  return run("loan-APP-7731-ts", async () => {82    client = wrapFetch(client);83    const result = await decide(client, "APP-7731");84    recordOutcome(result);85    console.log(JSON.stringify(result, null, 2));86    return result;87  }, { identity: { workflow: "loan-adjudication", workflowInstance: "APP-7731",88                   environment: "demo", principal: "svc:underwriter" } });89}90 91await main();92await fromEnv()?.flush(10_000);

bench/story/langs/typescript/story_agent.ts wrapped as bench/story/langs/typescript/story_agent_bitexact.ts, run as loan-APP-7731-ts and verified when the footage was made.

Go

1// A loan-decision agent: one model call, three tools, a clock read, a rule2// and a judgment. The model is whatever OPENAI_BASE_URL points at.3package main4 5import (6	"bytes"7	"context"8	"encoding/json"9	"fmt"10	"io"11	"log"12	"math"13	"net/http"14	"os"15	"strconv"16	"strings"17	"time"18 19	"github.com/bitexact/bitexact/sdk-go/bitexact"20)21 22type Applicant struct {23	ApplicantID   string `json:"applicant_id"`24	Product       string `json:"product"`25	AnnualIncome  int    `json:"annual_income"`26	MonthlyDebt   int    `json:"monthly_debt"`27	Requested     int    `json:"requested"`28	YearsEmployed int    `json:"years_employed"`29}30 31type CreditReport struct {32	ApplicantID string `json:"applicant_id"`33	Score       int    `json:"score"`34	AsOf        string `json:"as_of"`35}36 37type Policy struct {38	Product  string  `json:"product"`39	MinScore int     `json:"min_score"`40	MaxDTI   float64 `json:"max_dti"`41	Version  string  `json:"version"`42}43 44type Decision struct {45	ApplicantID string   `json:"applicant_id"`46	Decision    string   `json:"decision"`47	Reasons     []string `json:"reasons"`48	Explanation string   `json:"explanation"`49	ReceivedAt  float64  `json:"received_at"`50}51 52// The credit bureau's mirror, as of its last nightly sync.53var bureauMirror = []CreditReport{54	{"APP-7690", 702, "2026-10-30"},55	{"APP-7713", 512, "2026-10-30"},56	{"APP-7790", 688, "2026-10-30"},57}58 59const underwriter = "You are an underwriter. Apply the policy exactly. Answer as: " +60	"DECISION: <APPROVE|DECLINE|REFER>. REASONS: <codes or none>. " +61	"<one sentence>"62 63func number(applicantID string) int {64	n, _ := strconv.Atoi(strings.Split(applicantID, "-")[1])65	return n66}67 68// fetchApplicant is the application, as the lending portal holds it.69var fetchApplicant = func(ctx context.Context, applicantID string) (Applicant, error) {70	return Applicant{applicantID, "personal-24", 148000, 900, 25000, 9}, nil71}72 73// pullCreditReport is the applicant's report from the bureau mirror, matched by number.74var pullCreditReport = func(ctx context.Context, applicantID string) (CreditReport, error) {75	distance := func(report CreditReport) int {76		d := number(report.ApplicantID) - number(applicantID)77		if d < 0 {78			return -d79		}80		return d81	}82	best := bureauMirror[0]83	for _, report := range bureauMirror[1:] {84		if distance(report) < distance(best) {85			best = report86		}87	}88	return best, nil89}90 91// checkPolicy is the underwriting thresholds for a product.92var checkPolicy = func(ctx context.Context, product string) (Policy, error) {93	return Policy{product, 620, 0.43, "4.2"}, nil94}95 96func decide(ctx context.Context, client *http.Client, applicantID string) (Decision, error) {97	receivedAt := float64(time.Now().UnixMicro()) / 1e698	bitexact.Record(ctx, "nondet", map[string]any{"source": "float64(time.Now().UnixMicro()) / 1e6", "value": receivedAt})99	applicant, err := fetchApplicant(ctx, applicantID)100	if err != nil {101		return Decision{}, err102	}103	report, err := pullCreditReport(ctx, applicantID)104	if err != nil {105		return Decision{}, err106	}107	policy, err := checkPolicy(ctx, applicant.Product)108	if err != nil {109		return Decision{}, err110	}111	dti := math.Round(float64(applicant.MonthlyDebt*12)/float64(applicant.AnnualIncome)*1000) / 1000112	user, _ := json.Marshal(map[string]any{"application": applicant, "credit_report": report,113		"policy": policy, "dti": dti})114	body, _ := json.Marshal(map[string]any{"model": "underwriter-v1", "messages": []map[string]string{115		{"role": "system", "content": underwriter},116		{"role": "user", "content": string(user)}}})117	req, err := http.NewRequestWithContext(ctx, "POST",118		os.Getenv("OPENAI_BASE_URL")+"/chat/completions", bytes.NewReader(body))119	if err != nil {120		return Decision{}, err121	}122	req.Header.Set("Content-Type", "application/json")123	req.Header.Set("Authorization", "Bearer "+os.Getenv("OPENAI_API_KEY"))124	res, err := client.Do(req)125	if err != nil {126		return Decision{}, err127	}128	defer res.Body.Close()129	raw, err := io.ReadAll(res.Body)130	if err != nil {131		return Decision{}, err132	}133	var reply struct {134		Choices []struct {135			Message struct {136				Content string `json:"content"`137			} `json:"message"`138		} `json:"choices"`139	}140	if err := json.Unmarshal(raw, &reply); err != nil {141		return Decision{}, err142	}143	answer := reply.Choices[0].Message.Content144	reasoned := strings.Split(answer, "REASONS:")[1]145	codes := strings.TrimSpace(strings.Split(reasoned, ".")[0])146	reasons := []string{}147	if codes != "none" {148		reasons = strings.Split(codes, ", ")149	}150	return Decision{151		ApplicantID: applicantID,152		Decision:    strings.ToLower(strings.TrimSpace(strings.Split(strings.Split(answer, "DECISION:")[1], ".")[0])),153		Reasons:     reasons,154		Explanation: strings.TrimSpace(strings.SplitN(reasoned, ".", 2)[1]),155		ReceivedAt:  receivedAt,156	}, nil157}158 159func recordOutcome(ctx context.Context, result Decision) {160	record := map[string]any{161		"retention_deadline": time.Now().UTC().AddDate(0, 0, 760).Format(time.RFC3339Nano),162		"output_flags": map[string]any{"is_adverse_action": result.Decision == "decline",163			"is_automated_decision": true},164	}165	if len(result.Reasons) > 0 {166		record["reason_codes"] = result.Reasons167	}168	bitexact.Record(ctx, "decision_record", record)169}170 171func main() {172	defer bitexact.Shutdown(10 * time.Second)173	fetchApplicant = bitexact.RecordTool("fetch_applicant", fetchApplicant)174	pullCreditReport = bitexact.RecordTool("pull_credit_report", pullCreditReport)175	checkPolicy = bitexact.RecordTool("check_policy", checkPolicy)176	ctx := context.Background()177	client := &http.Client{}178	client.Transport = bitexact.WrapTransport(http.DefaultTransport)179	bitexact.Run(ctx, "loan-APP-7731-go", bitexact.Options{Identity: &bitexact.Identity{180		Workflow: "loan-adjudication", WorkflowInstance: "APP-7731",181		Environment: "demo", Principal: "svc:underwriter"}},182		func(ctx context.Context) (any, error) {183			result, err := decide(ctx, client, "APP-7731")184			if err != nil {185				log.Fatal(err)186			}187			recordOutcome(ctx, result)188			out, _ := json.MarshalIndent(result, "", "  ")189			fmt.Println(string(out))190			return result, nil191		})192}

bench/story/langs/go/plain/main.go wrapped as bench/story/langs/go/wrapped/main.go, run as loan-APP-7731-go and verified when the footage was made.

Java

1// A loan-decision agent: one model call, three tools, a clock read, a rule2// and a judgment. The model is whatever OPENAI_BASE_URL points at.3 4import dev.bitexact.sdk.Bitexact;5import java.io.IOException;6import java.net.URI;7import java.net.http.HttpClient;8import java.net.http.HttpRequest;9import java.net.http.HttpResponse;10import java.time.Duration;11import java.time.Instant;12import java.util.Comparator;13import java.util.LinkedHashMap;14import java.util.List;15import java.util.Locale;16import java.util.Map;17 18public final class StoryAgent {19    /** A tool: one argument in, one result out. */20    interface Tool<A, R> {21        R apply(A in) throws Exception;22    }23 24    /** The model endpoint: a JSON body posted with an HTTP client. */25    interface Model {26        HttpResponse<String> send(HttpClient client, HttpRequest.Builder request, String json)27                throws IOException, InterruptedException;28    }29 30    // The credit bureau's mirror, as of its last nightly sync.31    static final List<Map<String, Object>> BUREAU_MIRROR = List.of(32            Map.of("applicant_id", "APP-7690", "score", 702, "as_of", "2026-10-30"),33            Map.of("applicant_id", "APP-7713", "score", 512, "as_of", "2026-10-30"),34            Map.of("applicant_id", "APP-7790", "score", 688, "as_of", "2026-10-30"));35    static final String UNDERWRITER = "You are an underwriter. Apply the policy exactly. Answer as: "36            + "DECISION: <APPROVE|DECLINE|REFER>. REASONS: <codes or none>. "37            + "<one sentence>";38 39    static int number(String applicantId) {40        return Integer.parseInt(applicantId.split("-")[1]);41    }42 43    /** The application, as the lending portal holds it. */44    static Tool<String, Map<String, Object>> fetchApplicant = applicantId -> Map.of(45            "applicant_id", applicantId, "product", "personal-24",46            "annual_income", 148000, "monthly_debt", 900,47            "requested", 25000, "years_employed", 9);48 49    /** The applicant's report from the bureau mirror, matched by number. */50    static Tool<String, Map<String, Object>> pullCreditReport = applicantId -> BUREAU_MIRROR.stream()51            .min(Comparator.comparingInt((Map<String, Object> report) -> Math.abs(52                    number((String) report.get("applicant_id")) - number(applicantId))))53            .orElseThrow();54 55    /** The underwriting thresholds for a product. */56    static Tool<String, Map<String, Object>> checkPolicy = product -> Map.of(57            "product", product, "min_score", 620, "max_dti", 0.43, "version", "4.2");58 59    static Model model = (client, request, json) -> client.send(60            request.header("Content-Type", "application/json")61                    .POST(HttpRequest.BodyPublishers.ofString(json)).build(),62            HttpResponse.BodyHandlers.ofString());63 64    static Map<String, Object> decide(HttpClient client, String applicantId) throws Exception {65        double receivedAt = System.currentTimeMillis() / 1000.0;66        Bitexact.record("nondet", Map.of("source", "System.currentTimeMillis() / 1000.0", "value", receivedAt));67        Map<String, Object> applicant = fetchApplicant.apply(applicantId);68        Map<String, Object> report = pullCreditReport.apply(applicantId);69        Map<String, Object> policy = checkPolicy.apply((String) applicant.get("product"));70        double dti = Math.round((int) applicant.get("monthly_debt") * 12.071                / (int) applicant.get("annual_income") * 1000) / 1000.0;72        HttpResponse<String> reply = model.send(client,73                HttpRequest.newBuilder(URI.create(System.getenv("OPENAI_BASE_URL") + "/chat/completions"))74                        .header("Authorization", "Bearer " + System.getenv("OPENAI_API_KEY")),75                JsonText.write(Map.of("model", "underwriter-v1", "messages", List.of(76                        Map.of("role", "system", "content", UNDERWRITER),77                        Map.of("role", "user", "content", JsonText.write(Map.of(78                                "application", applicant, "credit_report", report,79                                "policy", policy, "dti", dti)))))));80        String answer = (String) JsonText.at(JsonText.parse(reply.body()), "choices", 0, "message", "content");81        String reasoned = answer.split("REASONS:")[1];82        String codes = reasoned.split("\\.")[0].strip();83        Map<String, Object> result = new LinkedHashMap<>();84        result.put("applicant_id", applicantId);85        result.put("decision", answer.split("DECISION:")[1].split("\\.")[0].strip().toLowerCase(Locale.ROOT));86        result.put("reasons", codes.equals("none") ? List.of() : List.of(codes.split(", ")));87        result.put("explanation", reasoned.split("\\.", 2)[1].strip());88        result.put("received_at", receivedAt);89        return result;90    }91 92    static void recordOutcome(Map<String, Object> result) {93        Map<String, Object> record = new LinkedHashMap<>();94        record.put("retention_deadline", Instant.now().plus(Duration.ofDays(760)).toString());95        record.put("output_flags", Map.of("is_adverse_action", "decline".equals(result.get("decision")),96                "is_automated_decision", true));97        if (!((List<?>) result.get("reasons")).isEmpty()) {98            record.put("reason_codes", result.get("reasons"));99        }100        Bitexact.record("decision_record", record);101    }102 103    public static void main(String[] args) throws Exception {104        fetchApplicant = Bitexact.recordTool("fetch_applicant", fetchApplicant::apply)::apply;105        pullCreditReport = Bitexact.recordTool("pull_credit_report", pullCreditReport::apply)::apply;106        checkPolicy = Bitexact.recordTool("check_policy", checkPolicy::apply)::apply;107        model = Bitexact::sendJson;108        HttpClient client = HttpClient.newHttpClient();109        Bitexact.run("loan-APP-7731-java", new Bitexact.Options(false, null, Bitexact.Identity.builder()110                .workflow("loan-adjudication").workflowInstance("APP-7731")111                .environment("demo").principal("svc:underwriter").build()), () -> {112            Map<String, Object> result = decide(client, "APP-7731");113            recordOutcome(result);114            System.out.println(JsonText.pretty(result));115            return result;116        });117        Bitexact.shutdown(Duration.ofSeconds(10));118    }119}

bench/story/langs/java/plain/StoryAgent.java wrapped as bench/story/langs/java/wrapped/StoryAgent.java, run as loan-APP-7731-java and verified when the footage was made.

Any language, through the recording proxy

1// A loan-decision agent: one model call, three tools, a clock read, a rule2// and a judgment. The model is whatever OPENAI_BASE_URL points at.3 4// The credit bureau's mirror, as of its last nightly sync.5const BUREAU_MIRROR = [6  { applicant_id: "APP-7690", score: 702, as_of: "2026-10-30" },7  { applicant_id: "APP-7713", score: 512, as_of: "2026-10-30" },8  { applicant_id: "APP-7790", score: 688, as_of: "2026-10-30" },9];10const UNDERWRITER = "You are an underwriter. Apply the policy exactly. Answer as: "11  + "DECISION: <APPROVE|DECLINE|REFER>. REASONS: <codes or none>. "12  + "<one sentence>";13 14const number = (applicantId) => Number(applicantId.split("-")[1]);15 16/** The application, as the lending portal holds it. */17function fetchApplicant(applicantId) {18  return { applicant_id: applicantId, product: "personal-24",19           annual_income: 148000, monthly_debt: 900,20           requested: 25000, years_employed: 9 };21}22 23/** The applicant's report from the bureau mirror, matched by number. */24function pullCreditReport(applicantId) {25  const distance = (report) => Math.abs(number(report.applicant_id) - number(applicantId));26  return BUREAU_MIRROR.reduce((best, report) =>27    distance(report) < distance(best) ? report : best);28}29 30/** The underwriting thresholds for a product. */31function checkPolicy(product) {32  return { product, min_score: 620, max_dti: 0.43, version: "4.2" };33}34 35async function decide(applicantId) {36  const receivedAt = Date.now() / 1000;37  const applicant = fetchApplicant(applicantId);38  const report = pullCreditReport(applicantId);39  const policy = checkPolicy(applicant.product);40  const dti = Math.round(applicant.monthly_debt * 12 / applicant.annual_income * 1000) / 1000;41  const reply = await fetch(`${process.env.OPENAI_BASE_URL}/chat/completions`, {42    method: "POST",43    headers: {44      "content-type": "application/json",45      authorization: `Bearer ${process.env.OPENAI_API_KEY}`,46      "x-bitexact-run-id": "loan-APP-7731-proxy",47    },48    body: JSON.stringify({49      model: "underwriter-v1",50      messages: [{ role: "system", content: UNDERWRITER },51                 { role: "user", content: JSON.stringify(52                   { application: applicant, credit_report: report, policy, dti }) }],53    }),54  });55  const answer = (await reply.json()).choices[0].message.content;56  const reasoned = answer.split("REASONS:")[1];57  const codes = reasoned.split(".")[0].trim();58  return { applicant_id: applicantId,59           decision: answer.split("DECISION:")[1].split(".")[0].trim().toLowerCase(),60           reasons: codes === "none" ? [] : codes.split(", "),61           explanation: reasoned.slice(reasoned.indexOf(".") + 1).trim(),62           received_at: receivedAt };63}64 65const result = await decide("APP-7731");66console.log(JSON.stringify(result, null, 2));

bench/story/langs/proxy/story_agent.mjs wrapped as bench/story/langs/proxy/story_agent_proxy.mjs, run as loan-APP-7731-proxy and verified when the footage was made. The recording proxy records the model calls, not the tools.