Realign code with the 2026-07-31 rulings

The trash sorts by modified descending — the arrival rank mint retires
(Ranks.isOrderedForTrash one comparator, loader + merged order agree;
the legacy deleted: migration stamps modified from the tombstone
timestamp where parseable; delete undo steps validate existence-only;
agent guide v8). Trash selection goes kind-blind — ranges, marquee,
Select All, and the successor walk sweep both kinds; the guard moves to
the exits (mixed-payload drop refusal, copy/cut validation). The copy
stamping preflight widens back to comment depth (load-scoped posture —
the board always loads, the gesture refuses whole). Fixes a latent
no-op: trashed-lane drag restore never fired (DragSession.beginLanes
hard-coded the board container).

2403 tests in 413 suites green.

Claude-Session: https://claude.ai/code/session_01CqjXB7ASoWtbyoGod68k97

KanbanTests/AgentGuideTests.swift

@@ -687,6 +687,24 @@ struct AgentGuideContentTests {
         #expect(content.contains("the trash is the recoverable path for both"))
     }
 
+    /// **v8: the arrival rank is retired** (08-agent-integration.md's own line, re-ruled 2026-07-31:
+    /// "move the card **or lane** folder into `<root>/.trash/` and restamp `modified` (the trash
+    /// sorts newest-first by that stamp … no rank to mint)"). The guide has to teach the *stamp* as
+    /// the position and to leave `order` alone — and, just as load-bearing, it must no longer teach
+    /// the rank formula: an agent still computing "smallest `order` minus 1024" would be writing a
+    /// key the app now deliberately preserves for the restore.
+    @Test("v8 teaches the stamp as the trash's order, and the rank formula is gone")
+    func v8TrashOrderingVocabularyIsPresent() {
+        let content = AgentGuide.content
+        #expect(content.contains("sorts by `modified`, newest first**"))
+        #expect(content.contains("the stamp is also the position"))
+        #expect(content.contains("there is no rank to mint"))
+        #expect(content.contains("leave `order` exactly as it is"))
+        // The retired formula, in the two spellings the v7 literal used.
+        #expect(!content.contains("smallest `order` already in `.trash/`"))
+        #expect(!content.contains("Arrivals go on top"))
+    }
+
     /// The pathfinder's guide taught `media/` and tombstone deletes; both are retired
     /// (01-storage-format.md ▸ Changes from the pathfinder schema; ▸ Deletion). The one legitimate
     /// mention of `deleted:` is the warning never to write it.