fix(vendor): the range watcher measures retail's cylinder-gap — the acceptance-band self-close is dead (Fable, from the live trace)

The vendor-verify gate's trace proved the entire walk-to-use chain
succeeding — arrival natural, Use dispatched, UseDone, the full
117-item ApproachVendor — and the panel still never appeared: the
range watcher's plain center-distance shortcut (AP-160) closed the
session the same frame it opened. The walk stops where the server
accepts (cylinder-gap: center minus both radii), which lands ~4.3 m
center against the vendor's authored 3 m — inside the acceptance
band, outside the watcher's bare-center check.

EnforceRange now measures cylinder-gap with both radii resolved
through the SAME ResolveObjectTableHost seam the movement arrival
uses — the seam whose absence was AP-160's original justification,
created by the previous commit's fix. The watcher and the walk agree
by construction. Unresolvable hosts degrade an operand to center
distance (close-early only, never holding a session ACE ended);
heights pass 0 (the host surface exposes radius only). AP-160
narrowed; #352 files the deferred cylinder-vs-center discriminating
unit test (needs a 38-member host fake; the live gate covered the
behavior today).

Clean-room complete solution: 11,536 passed / 4 skipped / 0 failed.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/ISSUES.md

@@ -24,6 +24,16 @@ What does NOT go here:
 - Every session: scan OPEN issues at start; promote/close anything we touched during the session before ending.
 - Promoting to a Phase: mark as `DONE (promoted to Phase X)` + commit SHA where the Phase entry landed.
 
+## #352 — Vendor range-watcher cylinder metric: discriminating unit test deferred
+
+**Status:** OPEN (filed 2026-08-08). The EnforceRange cylinder-gap fix
+(acceptance-band self-close, vendor-verify-gate.log evidence) landed with
+the existing 17-range/lifecycle tests green but WITHOUT a unit test that
+discriminates cylinder-vs-center (needs an IPhysicsObjHost fake — 38
+members — bound via BindObjectTableHostResolver; center>radius while
+cylinder<=radius stays open, radii-sabotage closes). Write it next
+session; the live gate covered the behavior.
+
 ## #351 — LandblockBuildOriginTests.FarLoad_StripsEnvCellsAndPhysics flake (Debug, load-sensitive)
 
 **Status:** OPEN (filed 2026-08-08). Seen three times today in Debug runs

src/AcDream.Runtime/Gameplay/RuntimeVendorRangeQuery.cs

@@ -87,18 +87,15 @@ public static class RuntimeVendorRangeQuery
     /// </para>
     ///
     /// <para>
-    /// <b>Distance metric divergence (register AP-160):</b> retail/ACE close
+    /// <b>Distance metric (AP-160 residual narrowed 2026-08-08):</b> the
-    /// on CYLINDER-GAP distance — both objects' own collision radius and
+    /// watcher measures retail's CYLINDER-GAP distance
-    /// height subtracted from the center distance
+    /// (<c>Position::cylinder_distance</c>) with both radii resolved through
-    /// (<c>Position::cylinder_distance</c>/ACE's <c>GetCylinderDistance</c>).
+    /// the same <c>ResolveObjectTableHost</c> seam the movement arrival
-    /// Runtime does not resolve a live per-NPC collision radius/height
+    /// uses — the plain-center-distance shortcut self-closed sessions the
-    /// outside the App-layer's Setup-cylinder resolver
+    /// server had just opened (the walk-to-use acceptance band; see the
-    /// (<c>WorldSelectionQuery</c>, App-only — out of reach per the
+    /// inline comment at the range check). Heights pass 0 (the host surface
-    /// Core-structure rules), so this uses plain 3D center-to-center
+    /// exposes radius only); an unresolvable host degrades that operand to
-    /// distance via <see cref="ObjectRangeMath.ObjectsInRange"/>'s
+    /// center distance, which only ever closes EARLY.
-    /// <c>useRadii: false</c> branch instead. Effect: the panel can close up
-    /// to (player radius + vendor radius) sooner than exact retail —
-    /// typically well under a meter for a two-legged NPC.
     /// </para>
     /// </summary>
     public static void EnforceRange(GameRuntime runtime)
@@ -148,15 +145,35 @@ public static class RuntimeVendorRangeQuery
         // an EXACT position match. That is retail's own behavior for a
         // radius-0 (or unauthored) handler, not a bug to paper over.
         float useRadius = vendorRecord.Snapshot.UseRadius ?? 0f;
+
+        // #vendor-verify-gate 2026-08-08: the watcher MUST measure with the
+        // same metric the walk-to-use arrival and ACE's acceptance use —
+        // cylinder-gap (center distance minus both bodies' radii), retail's
+        // Position::cylinder_distance. With plain center distance there is
+        // an acceptance band (bare UseRadius .. UseRadius + both radii,
+        // observed live: open accepted at 4.29 m center vs radius 3) where
+        // the server OPENS the session and this watcher instantly
+        // self-closed it — the panel flashed shut within one frame. The
+        // radii come from the same GetObjectA seam the movement arrival
+        // resolves through (ResolveObjectTableHost, lazy-minimal hosts
+        // included); an unresolvable host contributes 0 and degrades to
+        // center distance, which can only close EARLY, never hold a session
+        // ACE has ended.
+        float playerRadius =
+            runtime.EntityObjects.Physics.ResolveObjectTableHost(playerGuid)
+                ?.Radius ?? 0f;
+        float vendorRadius =
+            runtime.EntityObjects.Physics.ResolveObjectTableHost(vendorId)
+                ?.Radius ?? 0f;
         bool inRange = ObjectRangeMath.ObjectsInRange(
             AbsolutePosition(playerPosition),
-            0f,
+            playerRadius,
             0f,
             AbsolutePosition(vendorPosition),
-            0f,
+            vendorRadius,
             0f,
             useRadius,
-            useRadii: false,
+            useRadii: true,
             ignoreZDelta: false);
 
         if (!inRange)