Agent guide v6 - warn against lane-glob moves

A real agent incident (2026-07-29): moving cards with mv <lane>/* swept
the lane's own index.md along with the card folders, overwriting the
destination lane's identity file and leaving the source lane index-less
(the Implementation board briefly lost its lane titles; restored from
its auto-commit history). Both guide generations taught the correct
named-folder form but never said why it is load-bearing.

v6 adds the one-folder-at-a-time bullet to Moving and reordering:
a lane folder holds its own index.md beside its cards, so a glob
sweeps the identity file with them. Boards heal to v6 on their next
open per the first-line marker rule. The guide tests now derive
their expected marker and current/newer versions from
AgentGuide.version instead of a hardcoded literal, so the next bump
cannot silently break them.

1669 green on both schemes.

Claude-Session: https://claude.ai/code/session_01SR4XGjmBE16ZUYWpfFHXwY

Kanban/Storage/AgentGuide.swift

@@ -44,8 +44,11 @@ enum AgentGuide {
 
     /// The guide the app ships. **v4 was the pathfinder's**, and real boards carry it; v5 is the
     /// rewrite's guide (lanes, `.trash/`, `attachments/`, `modified-by`, the `CLAUDE.user.md`
-    /// pointer) and supersedes it on the next open.
+    /// pointer) and supersedes it on the next open. v6 adds the one-folder-at-a-time move warning:
-    static let version = 5
+    /// a real agent incident (2026-07-29) showed `mv <lane>/*` sweeping the lane's own `index.md`
+    /// along with the cards and destroying the destination lane's identity — the guide now says
+    /// *why* the named-folder form is load-bearing, not just what to type.
+    static let version = 6
 
     // MARK: - The version marker
 
@@ -327,6 +330,10 @@ enum AgentGuide {
     - Move to another lane: `mv <laneA>/<card-uuid> <laneB>/` — the folder move
       IS the move. Then set the card's `order` to place it among the
       destination's cards, update `modified`, and re-stamp `modified-by`.
+    - Move folders **one at a time, by name** — never `mv <laneA>/* <laneB>/`.
+      A lane folder holds its own `index.md` beside its cards, so a glob
+      sweeps the lane's identity file along with them and overwrites the
+      destination lane's.
     - Reorder within a lane: rewrite only that card's `order`.
 
     ## Editing and deleting

KanbanTests/AgentGuideTests.swift

@@ -95,7 +95,7 @@ struct AgentGuideMarkerTests {
     @Test("The guide the app ships carries the current marker in its first line")
     func shippedGuideCarriesTheMarker() {
         let firstLine = String(AgentGuide.content.prefix { !$0.isNewline })
-        #expect(firstLine.contains("lanework-agent-guide v5"))
+        #expect(firstLine.contains("lanework-agent-guide v\(AgentGuide.version)"))
         #expect(AgentGuide.installedVersion(of: AgentGuide.content) == AgentGuide.version)
         // Files the app creates end with LF (01-storage-format.md § Encoding and line endings).
         #expect(AgentGuide.content.hasSuffix("\n"))
@@ -152,8 +152,8 @@ struct AgentGuideDecisionTests {
     /// "Never downgraded" — a newer app version may have written it.
     @Test("Current and newer are left alone")
     func currentAndNewerAreLeftAlone() {
-        #expect(AgentGuide.decide(state(.file(text: guideText(version: 5)))) == .leaveAlone)
+        #expect(AgentGuide.decide(state(.file(text: guideText(version: AgentGuide.version)))) == .leaveAlone)
-        #expect(AgentGuide.decide(state(.file(text: guideText(version: 6)))) == .leaveAlone)
+        #expect(AgentGuide.decide(state(.file(text: guideText(version: AgentGuide.version + 1)))) == .leaveAlone)
         #expect(AgentGuide.decide(state(.file(text: AgentGuide.content))) == .leaveAlone)
     }
 
@@ -200,7 +200,7 @@ struct AgentGuideStoreTests {
         store.refreshAgentGuide()
 
         let written = try String(decoding: fixture.data(AgentGuide.filename), as: UTF8.self)
-        #expect(written.prefix { !$0.isNewline }.contains("lanework-agent-guide v5"))
+        #expect(written.prefix { !$0.isNewline }.contains("lanework-agent-guide v\(AgentGuide.version)"))
         #expect(written == AgentGuide.content)
         #expect(!fixture.exists(AgentGuide.userFilename))
         #expect(brackets.begins == 1, "one bracket — one app-mediated reload, one commit")
@@ -232,9 +232,10 @@ struct AgentGuideStoreTests {
     func currentGuideIsNotRewritten() throws {
         let fixture = try makeBoard()
         defer { fixture.tearDown() }
-        // Deliberately *not* the app's own text: a v5 marker is the whole gate, and a file carrying
+        // Deliberately *not* the app's own text: a current marker is the whole gate, and a file
-        // one must survive verbatim even when its body differs from what this version would write.
+        // carrying one must survive verbatim even when its body differs from what this version
-        let url = try writeRoot(AgentGuide.filename, Data(guideText(version: 5).utf8), in: fixture)
+        // would write.
+        let url = try writeRoot(AgentGuide.filename, Data(guideText(version: AgentGuide.version).utf8), in: fixture)
         let before = try stat(url)
         let store = try BoardStore(rootURL: fixture.root)
         let brackets = GuideBracketLog()