diff --git a/engineering/0018/SESSION-0018.0-TRANSCRIPT-2026-06-10T21-50--INPROGRESS.md b/engineering/0018/SESSION-0018.0-TRANSCRIPT-2026-06-10T21-50--INPROGRESS.md
index 3f665fe..e69b91c 100644
--- a/engineering/0018/SESSION-0018.0-TRANSCRIPT-2026-06-10T21-50--INPROGRESS.md
+++ b/engineering/0018/SESSION-0018.0-TRANSCRIPT-2026-06-10T21-50--INPROGRESS.md
@@ -18,8 +18,48 @@
 
 ```
 
+## Plan
+
+> Anchor: design specs/gitea-forge-backups.md (engineering#30) — SLICE-3
+> (Retention / rotation proven → guards BO-1 durability). Eligibility: ELIGIBLE (R2a).
+
+SLICE-3 proves T-4 (retention) on the scratch bucket
+`gs://wiggleverse-gitea-backups-scratch` (kept from SLICE-2): an over-age object
+is purged by the lifecycle policy, in-window objects and prior (noncurrent)
+versions survive (INV-5). Approach: mirror the prod bucket's config on scratch
+(versioning + the committed lifecycle JSON) plus a test rule keyed on
+`daysSinceCustomTime` (the controllable analogue of `age`, which cannot be
+back-dated); seed over-age / in-window / versioned-pair objects; wait for the
+GCS lifecycle pass (≤ 24–48 h) with a deterministic verify script; then update
+the infra doc + spec changelog and ship via PR. No prod mutation — prod's
+lifecycle/versioning were applied in SLICE-1 and are drift-checked read-only.
+
+## Execution log (checkpoint 2026-06-10T22:00 PST)
+
+- Branch `worktree-gitea-backups-slice-3` off `origin/main` (in the
+  slice-2 worktree, adopted — two concurrent sessions in flight: 0009, 0017).
+- Plan written: `docs/superpowers/plans/2026-06-10-gitea-backups-slice-3.md`.
+- Tasks 1–4 done: scratch bucket versioning enabled + T-4 lifecycle applied
+  (committed `infra/gitea-backup/t4-scratch-lifecycle.json`); prod bucket
+  drift-checked clean (lifecycle == committed JSON, versioning on);
+  `infra/gitea-backup/t4-retention-check.sh` (seed/verify) committed; fixtures
+  seeded (overage customTime 2026-04-27; inwindow; versioned pair) and verify
+  exercised its PENDING path (exit 1). Branch pushed.
+- Now waiting on the GCS lifecycle pass (≤ ~48 h; expected ≤ ~24 h), polling
+  hourly via verify.
+
 ## Deferred decisions
 
 _Autonomous-mode low-confidence calls the driver made and would have
 liked operator input on. Appended as the session runs; surfaced at
 finalize. Empty if none._
+
+- **T-4 over-age trigger uses `daysSinceCustomTime: 30`, not prod's `age: 30`**
+  — `age` cannot be back-dated, so executing the real rule means 30 days of
+  wall clock. Same threshold, same lifecycle Delete engine; substitution
+  documented in the infra doc. Confidence: high, but it is a fidelity call the
+  operator may want to revisit.
+- **The 7-day noncurrent purge is config-verified, not execution-verified** —
+  executing it adds ≥ 7 days for the same Delete machinery already exercised by
+  the over-age purge. Versioning *protection* (prior version survives) is
+  execution-verified.