diff --git a/launch-flap-churn.ps1 b/launch-flap-churn.ps1
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+++ b/launch-flap-churn.ps1
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+$env:ACDREAM_DAT_DIR   = "$env:USERPROFILE\Documents\Asheron's Call"
+$env:ACDREAM_LIVE      = "1"
+$env:ACDREAM_TEST_HOST = "127.0.0.1"
+$env:ACDREAM_TEST_PORT = "9000"
+$env:ACDREAM_TEST_USER = "testaccount"
+$env:ACDREAM_TEST_PASS = "testpassword"
+
+# Phase 1 portal-flood bounded-propagation PIN (2026-06-08).
+# Goal: on the doorway flap frames, show whether PortalVisibilityBuilder.Build's churn is
+# driven by redundant reciprocal back-contributions staying NON-EMPTY (the hypothesis).
+#
+#  1. [pv-input]    : per indoor-Build frame — outRoot + flood count + eye/player/yaw. The
+#                     flood-flip frames (e.g. 8<->3) are the flap; correlate with churn below.
+#  2. [portal-churn]: per Build call — cells, reEnqueues, rePoppedCells, maxPop=0x<cell>:<n>,
+#                     then per reciprocal call: recip[0x<neighbour> pre->post]. A back-contribution
+#                     that stays pre>0 AND post>0 on a cell that already contributed is the pin.
+# FLAP probe is intentionally OFF (its per-portal [flap] dump would drown the log).
+Remove-Item Env:\ACDREAM_PROBE_FLAP -ErrorAction SilentlyContinue
+$env:ACDREAM_PROBE_PVINPUT      = "1"
+$env:ACDREAM_PROBE_PORTAL_CHURN = "1"
+
+dotnet run --project src\AcDream.App\AcDream.App.csproj --no-build -c Debug 2>&1 |
+    Tee-Object -FilePath "flap-churn.log"