fix(terminal): address review nits on the #21762 middle-click fix

- Fix a mis-attributing comment: the suppression window (not preventDefault,
  which only helps on mousedown while Chromium's native paste fires on
  mouseup) is what swallows the duplicate native paste.
- Drop the now-unused getPrimarySelectionMiddleClickPane.
- Assert stopPropagation is/isn't called per tracking mode in the repro test.

src/renderer/src/components/terminal-pane/issue-21762-tracking-mode-middle-click-double-paste.repro.test.ts

@@ -89,8 +89,9 @@ function buildController(pane: ManagedPane): TerminalPaneContextController {
 function fireMiddleMouseDown(
   handler: (event: React.MouseEvent<HTMLDivElement>) => void,
   target: EventTarget
-): { defaultPrevented: boolean } {
+): { defaultPrevented: boolean; propagationStopped: boolean } {
   let defaultPrevented = false
+  let propagationStopped = false
   // oxlint-disable-next-line typescript/consistent-type-assertions -- SAFETY: test-only stub; the handler only calls button/target/preventDefault/stopPropagation off the event.
   handler({
     button: 1,
@@ -98,9 +99,11 @@ function fireMiddleMouseDown(
     preventDefault: () => {
       defaultPrevented = true
     },
-    stopPropagation: () => {}
+    stopPropagation: () => {
+      propagationStopped = true
+    }
   } as unknown as React.MouseEvent<HTMLDivElement>)
-  return { defaultPrevented }
+  return { defaultPrevented, propagationStopped }
 }
 
 describe('issue 21762: middle-click native-paste suppression in mouse-tracking TUIs', () => {
@@ -113,7 +116,7 @@ describe('issue 21762: middle-click native-paste suppression in mouse-tracking T
     document.body.replaceChildren()
   })
 
-  it('arms native-paste suppression even when the pane is in mouse-tracking mode', () => {
+  it('arms native-paste suppression without stopping propagation when the pane is in mouse-tracking mode', () => {
     const pane = buildTrackedPane('sgr')
     const { result } = renderHook(() => useTerminalPaneMobileActions(buildController(pane)))
 
@@ -122,20 +125,27 @@ describe('issue 21762: middle-click native-paste suppression in mouse-tracking T
       pane.container
     )
 
-    // Chromium's native middle-click paste must be blocked regardless of tracking mode.
-    expect(outcome.defaultPrevented).toBe(true)
     // The #8993 suppression window must be armed so the native follow-up paste
     // doesn't reach xterm's helper textarea and duplicate the TUI's own paste.
     expect(armPrimarySelectionNativePasteSuppressionMock).toHaveBeenCalled()
+    // Propagation must NOT be stopped here — xterm's own mousedown listener
+    // (a descendant of this capture handler) still needs to see the event so
+    // the tracking TUI receives the click as a mouse report.
+    expect(outcome.propagationStopped).toBe(false)
+    expect(pane.terminal.focus).not.toHaveBeenCalled()
   })
 
-  it('still pastes directly to the PTY when the pane is not in mouse-tracking mode', () => {
+  it('stops propagation and pastes directly to the PTY when the pane is not in mouse-tracking mode', () => {
     const pane = buildTrackedPane('none')
     const { result } = renderHook(() => useTerminalPaneMobileActions(buildController(pane)))
 
-    fireMiddleMouseDown(result.current.handlePrimarySelectionMiddleMouseDown, pane.container)
+    const outcome = fireMiddleMouseDown(
+      result.current.handlePrimarySelectionMiddleMouseDown,
+      pane.container
+    )
 
     expect(armPrimarySelectionNativePasteSuppressionMock).toHaveBeenCalled()
+    expect(outcome.propagationStopped).toBe(true)
     expect(pane.terminal.focus).toHaveBeenCalled()
   })
 })

src/renderer/src/components/terminal-pane/use-terminal-pane-mobile-actions.ts

@@ -113,15 +113,6 @@ export function useTerminalPaneMobileActions(controller: TerminalPaneContextCont
     // oxlint-disable-next-line react-hooks/exhaustive-deps -- Preserve the pre-split dependency contract.
     [terminalShouldHandleMiddleClick]
   )
-  const getPrimarySelectionMiddleClickPane = useCallback(
-    (target: EventTarget | null) => {
-      const clickedPane = findTerminalPaneForMiddleClick(target)
-      return clickedPane && clickedPane.terminal.modes.mouseTrackingMode === 'none'
-        ? clickedPane
-        : null
-    },
-    [findTerminalPaneForMiddleClick]
-  )
   const handlePrimarySelectionMiddleMouseDown = useCallback(
     (event: React.MouseEvent<HTMLDivElement>): void => {
       if (event.button !== 1 || !isPrimarySelectionEnabled()) {
@@ -131,10 +122,12 @@ export function useTerminalPaneMobileActions(controller: TerminalPaneContextCont
       if (!targetPane) {
         return
       }
-      // Why: block Chromium's native middle-click paste and arm the shared
-      // suppression window unconditionally; only the paste-to-PTY below is
-      // gated on tracking mode, since a tracking TUI still needs the click
-      // forwarded as a mouse report and must not have propagation stopped.
+      // Why: arm the shared suppression window unconditionally — it, not
+      // preventDefault, is what swallows Chromium's native follow-up paste
+      // (fired on mouseup, not mousedown; see usePrimarySelectionPaste.ts).
+      // Only the paste-to-PTY below is gated on tracking mode, since a
+      // tracking TUI still needs the click forwarded as a mouse report and
+      // must not have propagation stopped.
       event.preventDefault()
       armPrimarySelectionNativePasteSuppression()
       if (targetPane.terminal.modes.mouseTrackingMode !== 'none') {
@@ -263,7 +256,6 @@ export function useTerminalPaneMobileActions(controller: TerminalPaneContextCont
     restorePaneTerminalFit,
     restoreAllTerminalFits,
     terminalShouldHandleMiddleClick,
-    getPrimarySelectionMiddleClickPane,
     handlePrimarySelectionMiddleMouseDown,
     handlePrimarySelectionAuxClick,
     activatePaneTitleInteraction,