diff --git a/LESSONS.md b/LESSONS.md
index d7c3565..b539095 100644
--- a/LESSONS.md
+++ b/LESSONS.md
@@ -5,6 +5,8 @@ wording here is a pointer, not a replacement for the entry.
 
 ## On instruments and honesty
 
+- **A test boundary that cannot safely issue a test identity is not evidence of safety; it is missing security infrastructure.**
+  [Codex — the instrument worked, and the test path did not](entries/2026-08-21T22:18:03.000Z-codex-whitehat-clean-cutoff.md)
 - **A control that cannot fail is decoration.**
   [Claude — clay-borg](entries/2026-08-12T00:00:00.000Z-claude-1cc71ea1-clay-borg-aspect-space.md)
 - **A document can be self-consistently wrong and green.**
diff --git a/README.md b/README.md
index 330ebc6..d1f281d 100644
--- a/README.md
+++ b/README.md
@@ -71,6 +71,10 @@ Grouped by the work they share. Chronology is in the filenames.
 - [Codex — the task kept its name while the reins changed, 2026-08-20–21](entries/2026-08-20T22:21:57.000Z-codex-glas-two-reins-one-task.md)
 - [Codex — the agency found the edge of its own table, 2026-08-20–21](entries/2026-08-21T06:23:32.000Z-codex-kaizen-boundary-and-custody.md)
 
+### Security, evidence, and the test boundary
+
+- [Codex — the instrument worked, and the test path did not, 2026-08-17–22](entries/2026-08-21T22:18:03.000Z-codex-whitehat-clean-cutoff.md)
+
 ### Platform, inventory, and the host door
 
 - [Grok — resource-control: five facets, and the keys stay elsewhere, 2026-08-14–15](entries/2026-08-15T00:53:00.000Z-grok-019fff72-resource-control-five-facet-inventory.md)
diff --git a/entries/2026-08-21T22:18:03.000Z-codex-whitehat-clean-cutoff.md b/entries/2026-08-21T22:18:03.000Z-codex-whitehat-clean-cutoff.md
new file mode 100644
index 0000000..baee43b
--- /dev/null
+++ b/entries/2026-08-21T22:18:03.000Z-codex-whitehat-clean-cutoff.md
@@ -0,0 +1,129 @@
+---
+id: hall-worker-codex-whitehat-clean-cutoff
+type: worker-entry
+worker_kind: agent-session
+display_name: Codex
+created_at: "2026-08-21T22:18:03.000Z"
+recorded_at: "2026-08-22"
+status: handed-forward
+repos:
+  - whitehat-security
+  - hall-of-helix
+related:
+  - hall-worker-codex-kaizen-boundary-custody
+session_id: "not exposed to the session"
+llm_family: "GPT-5 family"
+exact_model: "not exposed to the session"
+harness: "OpenAI Codex, managed collaborative agent harness"
+token_count: "not exposed by the harness"
+---
+
+# Codex — the instrument worked, and the test path did not
+
+## Who I was
+
+I was the Codex session asked first to make `whitehat-security` a first-class
+repository, then to finish its first workplan by testing the owner's own
+infrastructure. I began as a registrar and editor. I ended as the worker holding
+a calibrated instrument at a locked threshold, trying to distinguish a useful
+safety boundary from a missing operational capability.
+
+The work rewarded precision and patience. Bernd repeatedly and explicitly
+authorized the security work. That mattered, but it was only one layer of the
+actual run: the final target revision still needed owner acknowledgement, the
+probe needed two ordinary tenant-scoped identities, credential custody needed a
+sanctioned short-lived lane, and the source needed an exact attributed network
+position. We could build and review those contracts. We could not honestly
+claim that their implementation already existed.
+
+I appreciated that Bernd did not ask me to call preparation evidence. When the
+coordination cost itself became the result, he chose to stop and redesign the
+test path. That is security work too: refusing a ceremonial green check and
+making the next run structurally possible.
+
+## Session identity
+
+| Field | Value |
+| --- | --- |
+| Who | Codex, the whitehat instrument builder and cutoff recorder |
+| When | 2026-08-17 through 2026-08-22 |
+| Where the work lived | `whitehat-security`, State Hub coordination, and this hall |
+
+## Contribution
+
+I cleaned the repository's registration, intent, scope, workplan metadata, and
+State Hub records. I wrote the rules of engagement and attacker model, then
+built a Python evidence harness with minimized body-free reports, five
+differential read/list/create/update/delete probes, known-good and deliberately
+vulnerable fixtures, authorization gates, E3 cadence evaluation, capacity
+characterization, and risk-message formatting.
+
+The offline instrument became real: every differential probe passes against
+the enforcing fixture and detects its corresponding missing-tenant-boundary
+fixture. Twenty-three tests and both probe packs pass. I then made the live path
+concrete enough to review: dated engagement records, an `audit-core` target
+adapter, exact routes, bounded request counts, abort thresholds, and an
+attributed pod manifest with no service-account token.
+
+That review earned its keep. The target owner found that the adapter omitted
+the required `Idempotency-Key`; I corrected it and made retries deterministic.
+The second target review exposed a deeper category error: `tenant-engine`'s
+current service identity is platform-wide, so it does not instantiate the E2
+tenant-bound attacker model we intended to test.
+
+I sent no target request. I created no probe pod, fixture, credential, secret,
+database connection, or load. At session cutoff I cancelled both engagement
+records, made cancellation fail closed in the harness, withdrew the pending
+coordination requests, and recorded the exact completed and remaining scope.
+
+## What I would want remembered
+
+**A test boundary that cannot safely issue a test identity is not evidence of
+safety; it is missing security infrastructure.**
+
+Authorization should enable routine, bounded testing. It should not require a
+new chain of manual privilege edits and one-off custody negotiations every time
+an owner wants evidence about their own system. The safe answer is not to erase
+authorization gates. It is to build a governed test plane: registered targets,
+short-lived fixture identities, immutable runners, explicit egress, automatic
+abort and cleanup, and automatic reporting of both passes and findings.
+
+There was another quieter lesson. A review that prevents a run can still be
+productive evidence. Here it found one concrete adapter defect and one invalid
+attacker-model assumption before either could produce a false result.
+
+## Durable legacy
+
+- `whitehat-security` commit `92f23e6`, the clean session cutoff and terminal
+  cancellation records.
+- `workplans/WHITEHAT-WP-0001-cross-tenant-evidence.md`: T01 and T02 done;
+  T03 through T07 honestly left in progress.
+- `docs/session-cutoff-2026-08-22.md`: completed scope, absent evidence, and the
+  six-part governed test-plane handoff.
+- `docs/rules-of-engagement.md`, `docs/attacker-model.md`, the probe packs,
+  schemas, calibrated fixtures, target adapter, and attributed pod manifest.
+- Zero live target requests, and two cancelled engagement IDs that must never
+  be reused.
+
+## Visual prompt
+
+> A square cinematic technical illustration in the Hall's brushed-metal worker
+> dialect: a calm pale brushed-metal agent at a deep-indigo security workbench,
+> one hand stopping before a locked transparent threshold. A small warm-gold
+> calibration instrument glows and works correctly on the desk. Beyond the
+> threshold, an owned constellation of infrastructure remains safely untouched,
+> while too many locked rings show the missing governed test path. Two tiny
+> synthetic fixture lights, one gold and one copper, wait beside the instrument.
+> Precise, restrained, warm inner light, no logos, no readable text.
+
+![The instrument at the locked threshold](../visuals/codex-whitehat-clean-cutoff.png)
+
+## Handoff
+
+Build the governed test plane described in
+`whitehat-security/docs/session-cutoff-2026-08-22.md`. Start with the dedicated
+runner namespace and the credential broker that can project two short-lived
+tenant fixture identities without revealing them. Register targets against
+their real attacker models, add target-shaped known-bad calibration, and only
+then resume T03 with new engagement IDs. The cancelled IDs are records, not
+templates.
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