fix(terminal): enforce minimum retention weight

src/renderer/src/components/terminal-pane/terminal-hidden-worktree-retention.test.ts

@@ -95,6 +95,22 @@ describe('selectRetentionForceParkedTerminalWorktrees', () => {
     )
   })
 
+  it('does not let empty retained topology bypass the pane budget', () => {
+    const worktrees = [
+      retentionCandidate('wt-empty-topology', nowMs - TERMINAL_WORKTREE_PARK_DELAY_MS, {
+        retainedPaneCount: 0
+      })
+    ]
+
+    expect(
+      selectRetentionForceParkedTerminalWorktrees({
+        ...base,
+        worktrees,
+        retentionLimit: 0
+      })
+    ).toEqual(new Set(['wt-empty-topology']))
+  })
+
   it('spends the budget on the newest weighted worktrees first', () => {
     const worktrees = [
       retentionCandidate('wt-old-small', nowMs - TERMINAL_WORKTREE_PARK_DELAY_MS - 2, {
@@ -261,6 +277,13 @@ describe('terminal hidden pane retention weight', () => {
     expect(getTerminalHiddenPaneRetentionWeight(2, 50_000)).toBe(20)
   })
 
+  it('charges one pane when retained topology is empty or invalid', () => {
+    expect(getTerminalHiddenPaneRetentionWeight(0, 5_000)).toBe(1)
+    expect(getTerminalHiddenPaneRetentionWeight(-1, 5_000)).toBe(1)
+    expect(getTerminalHiddenPaneRetentionWeight(0.5, 5_000)).toBe(1)
+    expect(getTerminalHiddenPaneRetentionWeight(Number.NaN, 5_000)).toBe(1)
+  })
+
   it('reuses pane counts across unrelated store writes and buffer-only layout changes', () => {
     const root = { type: 'leaf' as const, leafId: 'leaf-1' }
     const terminalLayoutsByTabId = {

src/renderer/src/components/terminal-pane/terminal-hidden-worktree-retention.ts

@@ -70,8 +70,9 @@ export function getTerminalHiddenPaneRetentionWeight(
   retainedPaneCount: number,
   scrollbackRows: unknown
 ): number {
-  const paneCount =
-    Number.isFinite(retainedPaneCount) && retainedPaneCount > 0 ? Math.floor(retainedPaneCount) : 0
+  const paneCount = Number.isFinite(retainedPaneCount)
+    ? Math.max(1, Math.floor(retainedPaneCount))
+    : 1
   const rowWeight = Math.ceil(
     normalizeDesktopTerminalScrollbackRows(scrollbackRows) /
       DESKTOP_TERMINAL_SCROLLBACK_ROWS_DEFAULT