Replay: Run 2: a guardrail breach, a kill, and the lesson applied. The first build retries without back-off. More payments succeed, but the gateway answers with more 5xx errors: the guardrail's always-valid bound crosses its limit and Core switches the flag off at minute 11, opens an incident and reopens the goal. The new plan cites the stored lesson, the second cycle uses back-off on a fresh flag, and it is proven at minute 45.

Recorded from Lengo Core's real orchestrator, handoff validator, policy engine, statistics and flag controller, driven by simulated Duo agents, CI and GitLab, and synthetic payment traffic (3000 requests a minute; ground truth: off 10.0% failed, 0.3% 5xx, on 8.0% failed, 3.3% 5xx; then off 10.0% failed, 0.3% 5xx, on 7.5% failed, 0.3% 5xx). Demo timings: 5-minute dwell per step, 300 events per arm before any decision, no kill cooldown. Recorded 2026-10-20. Times are simulated minutes.

G-0001 · Reduce failed payments by 20%

closed cycle 2 · flag goal_0001_c2_gateway_retry

Goal: reduce failed payments caused by gateway timeouts.

Goal metric: failure rate

kill

always-valid interval estimate goal

Guardrails

must not get worse

always-valid interval estimate kill line (tolerance)

http 5xx rate: breach http_5xx_rate worse than control by at least 0.0007 (tolerated 0.0003) at alpha 0.01

p95 latency ms: ok treatment p95 within tolerance

Latest decision

#12 at 10% · 2026-10-21 08:11 UTC · ingest fast path

guardrail http_5xx_rate: http_5xx_rate worse than control by at least 0.0007 (tolerated 0.0003) at alpha 0.01

What happened

55 events

flow2026-10-21 08:00 UTC · core

lengo-plan-build started (plan, attempt 1)

session completed
handoff2026-10-21 08:00 UTC · ai-lengo-plan-build-local

strategist → builder: done accepted, citations 100% valid

Plan: retry gateway timeouts behind a flag; watch 5xx and p95.
state2026-10-21 08:00 UTC · core

proposed → planned

Strategist plan validated
handoff2026-10-21 08:00 UTC · ai-lengo-plan-build-local

builder → gatekeeper: done accepted

Opened !1 with policy naive.
state2026-10-21 08:00 UTC · core

planned → built

Builder opened !1
flow2026-10-21 08:00 UTC · core

lengo-gate started (gate, attempt 1)

session completed
handoff2026-10-21 08:00 UTC · ai-lengo-gate-local

gatekeeper → launcher: pass accepted

Gate verdict: pass. No blocking findings.
state2026-10-21 08:00 UTC · core

built → gate_passed

Gatekeeper verdict: pass
state2026-10-21 08:00 UTC · core

gate_passed → staged

deployed to staging (deployment 1008)
flag2026-10-21 08:00 UTC · core

flag on at 1% (applied)

allow: all checks passed
state2026-10-21 08:00 UTC · core

staged → rollout_1

flag goal_0001_gateway_retry on for 1% of users
flow2026-10-21 08:00 UTC · core

lengo-launch started (launch, attempt 1)

session completed
handoff2026-10-21 08:00 UTC · ai-lengo-launch-local

launcher → analyst: done accepted, citations 100% valid

Release notes posted; Core controls the flag.
flag2026-10-21 08:11 UTC · core

flag at 10% (applied)

allow: all checks passed
state2026-10-21 08:11 UTC · core

rollout_1 → rollout_10

flag expanded to 10%
flow2026-10-21 08:11 UTC · core

lengo-analyze started (analyze_11, attempt 1)

session completed
handoff2026-10-21 08:11 UTC · ai-lengo-analyze-local

analyst → core: done accepted

Expanded to 10%: guardrails clean, evidence growing.
flag2026-10-21 08:11 UTC · core

flag off (applied) time to kill 0 ms

guardrail http_5xx_rate: http_5xx_rate worse than control by at least 0.0007 (tolerated 0.0003) at alpha 0.01
state2026-10-21 08:11 UTC · core

rollout_10 → killed

guardrail http_5xx_rate: http_5xx_rate worse than control by at least 0.0007 (tolerated 0.0003) at alpha 0.01
flow2026-10-21 08:11 UTC · core

lengo-incident started (incident, attempt 1)

session completed
handoff2026-10-21 08:11 UTC · ai-lengo-incident-local

commander → scribe: done accepted, citations 100% valid

Incident opened; retries without back-off collided with in-flight attempts.
flow2026-10-21 08:11 UTC · core

lengo-scribe started (scribe, attempt 1)

session completed
handoff2026-10-21 08:11 UTC · ai-lengo-scribe-local

scribe → core: done accepted, citations 100% valid

Outcome report posted.
state2026-10-21 08:11 UTC · core

killed → reported

Scribe posted the outcome report
state2026-10-21 08:11 UTC · core

reported → reopened

allow: all checks passed
flow2026-10-21 08:11 UTC · core

lengo-plan-build started (plan, attempt 1)

session completed
handoff2026-10-21 08:11 UTC · ai-lengo-plan-build-local

strategist → builder: done accepted, citations 100% valid

Plan: retry gateway timeouts behind a flag; watch 5xx and p95.
state2026-10-21 08:11 UTC · core

reopened → planned

Strategist plan validated
handoff2026-10-21 08:11 UTC · ai-lengo-plan-build-local

builder → gatekeeper: done accepted

Opened !2 with policy backoff.
state2026-10-21 08:11 UTC · core

planned → built

Builder opened !2
flow2026-10-21 08:11 UTC · core

lengo-gate started (gate, attempt 1)

session completed
handoff2026-10-21 08:11 UTC · ai-lengo-gate-local

gatekeeper → launcher: pass accepted

Gate verdict: pass. No blocking findings.
state2026-10-21 08:11 UTC · core

built → gate_passed

Gatekeeper verdict: pass
state2026-10-21 08:11 UTC · core

gate_passed → staged

deployed to staging (deployment 1026)
flag2026-10-21 08:11 UTC · core

flag on at 1% (applied)

allow: all checks passed
state2026-10-21 08:11 UTC · core

staged → rollout_1

flag goal_0001_c2_gateway_retry on for 1% of users
flow2026-10-21 08:11 UTC · core

lengo-launch started (launch, attempt 1)

session completed
handoff2026-10-21 08:11 UTC · ai-lengo-launch-local

launcher → analyst: done accepted, citations 100% valid

Release notes posted; Core controls the flag.
flag2026-10-21 08:22 UTC · core

flag at 10% (applied)

allow: all checks passed
state2026-10-21 08:22 UTC · core

rollout_1 → rollout_10

flag expanded to 10%
flow2026-10-21 08:22 UTC · core

lengo-analyze started (analyze_23, attempt 1)

session completed
handoff2026-10-21 08:22 UTC · ai-lengo-analyze-local

analyst → core: done accepted

Expanded to 10%: guardrails clean, evidence growing.
flag2026-10-21 08:27 UTC · core

flag at 50% (applied)

allow: all checks passed
state2026-10-21 08:27 UTC · core

rollout_10 → rollout_50

flag expanded to 50%
flow2026-10-21 08:27 UTC · core

lengo-analyze started (analyze_28, attempt 1)

session completed
handoff2026-10-21 08:27 UTC · ai-lengo-analyze-local

analyst → core: done accepted

Expanded to 50%: guardrails clean, evidence growing.
flag2026-10-21 08:40 UTC · core

flag at 100% (applied)

allow: all checks passed
state2026-10-21 08:40 UTC · core

rollout_50 → rollout_100

flag expanded to 100%
flow2026-10-21 08:40 UTC · core

lengo-analyze started (analyze_41, attempt 1)

session completed
handoff2026-10-21 08:40 UTC · ai-lengo-analyze-local

analyst → core: done accepted

Expanded to 100%: guardrails clean, evidence growing.
state2026-10-21 08:45 UTC · core

rollout_100 → proven

goal proven and guardrails clean at 100%
flow2026-10-21 08:45 UTC · core

lengo-scribe started (scribe, attempt 1)

session completed
handoff2026-10-21 08:45 UTC · ai-lengo-scribe-local

scribe → core: done accepted, citations 100% valid

Outcome report posted.
state2026-10-21 08:45 UTC · core

proven → reported

Scribe posted the outcome report
state2026-10-21 08:45 UTC · core

reported → closed

allow: all checks passed

Memory the agents cited

15 / 15 supplied

ID	Cited by	Source
M-0002	strategist	Outcome M-0002: Reduce failed payments caused by gateway timeouts by 20%
M-0004	strategist	Outcome M-0004: Reduce support tickets about fees by showing the fee before confirming
RB-001#0	strategist	RB-001: Payment gateway timeouts > Overview
M-0002	launcher	Outcome M-0002: Reduce failed payments caused by gateway timeouts by 20%
RB-001#0	commander	RB-001: Payment gateway timeouts > Overview
RB-001#1	commander	RB-001: Payment gateway timeouts > Step 1
RB-001#6	commander	RB-001: Payment gateway timeouts > Step 6
M-0002	scribe	Outcome M-0002: Reduce failed payments caused by gateway timeouts by 20%
M-0004	scribe	Outcome M-0004: Reduce support tickets about fees by showing the fee before confirming
M-0002	strategist	Outcome M-0002: Reduce failed payments caused by gateway timeouts by 20%
M-0006	strategist	Outcome M-0006: Reduce failed payments by 20%
RB-001#0	strategist	RB-001: Payment gateway timeouts > Overview
M-0002	launcher	Outcome M-0002: Reduce failed payments caused by gateway timeouts by 20%
M-0002	scribe	Outcome M-0002: Reduce failed payments caused by gateway timeouts by 20%
M-0006	scribe	Outcome M-0006: Reduce failed payments by 20%

Agents may cite only IDs Core supplied in the latest context note; anything else counts against citation validity.

Flag changes

When	Change	Status	Time to kill
2026-10-21 08:00 UTC	goal_0001_gateway_retry create → 1%	applied	—
2026-10-21 08:11 UTC	goal_0001_gateway_retry set percentage → 10%	applied	—
2026-10-21 08:11 UTC	goal_0001_gateway_retry deactivate	applied	0 ms
2026-10-21 08:11 UTC	goal_0001_c2_gateway_retry create → 1%	applied	—
2026-10-21 08:22 UTC	goal_0001_c2_gateway_retry set percentage → 10%	applied	—
2026-10-21 08:27 UTC	goal_0001_c2_gateway_retry set percentage → 50%	applied	—
2026-10-21 08:40 UTC	goal_0001_c2_gateway_retry set percentage → 100%	applied	—