fix: duplicate card/note creation under StrictMode (updater side effects)

frontend/e2e/atlas-authoring.spec.ts

@@ -64,6 +64,9 @@ test('atlas creation core: tray, placement popover, right-click create, sticky n
     await expect(draftTextarea).toHaveCount(0)
     const sticky = page.getByTestId('atlas-sticky-note').filter({ hasText: 'ZzE2eStickyNoteText' })
     await expect(sticky).toBeVisible()
+    // Regression: one blur commits exactly ONE note (the same
+    // StrictMode updater-side-effect class as the card popover).
+    await expect(sticky).toHaveCount(1)
     // No kind chip (a card's own front face always renders one) and a
     // distinct node type from a card.
     await expect(sticky.locator('[data-testid="atlas-note-file-tag"]')).toHaveCount(0)
@@ -139,6 +142,11 @@ test('atlas creation core: tray, placement popover, right-click create, sticky n
     await popover.getByTestId('atlas-placement-submit').click()
     await expect(popover).not.toBeVisible()
     await expect(noteCard(page, 'ZzE2eRootCard')).toBeVisible()
+    // Regression: one confirm creates exactly ONE card. StrictMode
+    // double-invokes setState updater functions, so a service call
+    // living inside one fires twice -- every C-flow confirm produced
+    // duplicate cards until the call moved out of the updater.
+    await expect(noteCard(page, 'ZzE2eRootCard')).toHaveCount(1)
 
     // --- After zooming into an area, repeat -> the new card's parent
     // IS that area, not root: "Example area" seeds exactly 2 children

frontend/src/atlas/useAtlasCreation.ts

@@ -179,9 +179,19 @@ export function useAtlasCreation({ parentID, allCards, notes, readOnly, screenTo
 
   const cancelPopover = useCallback(() => setPopover(null), [])
 
+  // The service calls below live OUTSIDE any setState updater on
+  // purpose: updater functions must be pure -- React StrictMode
+  // double-invokes them, which turned every confirm into TWO created
+  // cards/notes (regression: duplicate creation under the dev build).
+  // Reading `popover` from the closure is safe here; this callback's
+  // identity changing when the popover opens/closes is bounded and
+  // never feeds the sticky-node data path that caused the React #185
+  // loop this file's other comments describe.
   const submitPopover = useCallback((kindID: string, title: string) => {
-    setPopover((pending) => {
-      if (!pending) return null
+    const pending = popover
+    if (!pending) return
+    setPopover(null)
+    {
       if (pending.mode === 'create' && pending.slotLinkFromCardID && pending.slotLinkKindID) {
         // Slot-drag guided-create (goal 0081 slice A4, D1=B): atomic,
         // so the map never shows a card with a missing link or a link
@@ -226,25 +236,25 @@ export function useAtlasCreation({ parentID, allCards, notes, readOnly, screenTo
           .then(() => refreshAtlas())
           .catch(console.error)
       }
-      return null
-    })
-  }, [parentID])
+    }
+  }, [popover, parentID])
 
   const commitDraftNote = useCallback((text: string) => {
-    setDraftNoteFlowPos((pos) => {
+    const pos = draftNoteFlowPos
+    const override = draftNoteParentOverride
+    setDraftNoteFlowPos(null)
+    setDraftNoteParentOverride(null)
+    {
       const trimmed = text.trim()
       if (pos && trimmed) {
-        const override = draftNoteParentOverride
         const targetParentID = override ?? parentID
         const position = override ? freeChildPosition(allCardsRef.current, override) : { X: pos.x, Y: pos.y }
         void AtlasService.CreateNote(trimmed, position, targetParentID)
           .then(() => refreshAtlas())
           .catch(console.error)
       }
-      return null
-    })
-    setDraftNoteParentOverride(null)
-  }, [parentID, draftNoteParentOverride])
+    }
+  }, [parentID, draftNoteFlowPos, draftNoteParentOverride])
   const cancelDraftNote = useCallback(() => {
     setDraftNoteFlowPos(null)
     setDraftNoteParentOverride(null)