refactor(terminal): fold the owned-leaf rule into its only consumer

The leaf-claims module had two functions for two readers; with the hydration heal
gone, one has no reader and the other has exactly one. Inline it, keeping the
empty-binding filter and the reason for it, and drop the module.

Also rewords the comments that explained an unbound leaf by the heal. A pane keeps
its leaf after its PTY exits, which is the reason that outlives this change.

src/renderer/src/components/terminal-pane/terminal-layout-leaf-claims.ts

@@ -1,46 +0,0 @@
-import type { TerminalPaneLayoutNode } from '../../../../shared/terminal-tab-types'
-import { collectLeafIdsInOrder } from './terminal-layout-leaf-ids'
-
-export type TerminalLayoutLeafClaims = {
-  root: TerminalPaneLayoutNode | null
-  activeLeafId?: string | null
-  ptyIdsByLeafId?: Record<string, string>
-}
-
-/**
- * Leaf ids a rootless layout actually binds. The persisted map types its values as a plain
- * string, so an empty one survives the schema and is not a binding: counting it would let a
- * layout look like it holds a leaf no session is attached to.
- */
-function boundLeafIds(layout: TerminalLayoutLeafClaims): string[] {
-  return Object.entries(layout.ptyIdsByLeafId ?? {})
-    .filter(([, ptyId]) => Boolean(ptyId))
-    .map(([leafId]) => leafId)
-}
-
-/**
- * Leaf ids this layout holds, read generously: its tree, or — for a rootless layout, which binds
- * its sole pane off-tree — every leaf it binds. Use this to ask "does some pane already hold
- * this?", where over-counting only costs a reveal that adopts instead of minting.
- *
- * A binding whose leaf has left a rooted tree reattaches nothing, so it is excluded either way.
- */
-export function collectOwnedLeafIds(layout: TerminalLayoutLeafClaims): Set<string> {
-  return new Set(layout.root ? collectLeafIdsInOrder(layout.root) : boundLeafIds(layout))
-}
-
-/**
- * Leaf ids this layout may take from another tab, read narrowly. Same as the owned set for a
- * rooted layout, but a rootless one proves only its sole off-tree pane, or the one its
- * `activeLeafId` names: a never-pruned map holds more than it owns, and claiming those evicts
- * the live row that really owns them (#13098). Mirrors the `owned`/`claimable` split in
- * `terminal-session-row-hydration.ts`, which is the guard that caught #13060.
- */
-export function collectClaimableLeafIds(layout: TerminalLayoutLeafClaims): Set<string> {
-  if (layout.root) {
-    return new Set(collectLeafIdsInOrder(layout.root))
-  }
-  const leafIds = boundLeafIds(layout)
-  const provenLeafId = leafIds.length === 1 ? leafIds[0] : layout.activeLeafId
-  return new Set(leafIds.filter((leafId) => leafId === provenLeafId))
-}

src/renderer/src/lib/terminal-pty-pane-owner.ts

@@ -1,4 +1,5 @@
-import { collectOwnedLeafIds } from '@/components/terminal-pane/terminal-layout-leaf-claims'
+import { collectLeafIdsInOrder } from '@/components/terminal-pane/terminal-layout-leaf-ids'
+import type { TerminalLayoutSnapshot } from '../../../shared/terminal-tab-types'
 import type { AppState } from '@/store/types'
 
 /** No `tabsByWorktree`: ownership is tab-keyed, so no worktree key participates. */
@@ -22,6 +23,26 @@ export type TerminalPtyPaneOwnerOptions = {
   preferTabId?: string
 }
 
+/**
+ * Leaf ids this layout holds: its tree, or — for a rootless layout, which binds its sole pane
+ * off-tree — every leaf it actually binds. A binding whose leaf has left a rooted tree reattaches
+ * nothing, so it must not outrank a live pane (#13098).
+ *
+ * Why the truthiness check: the persisted map types its values as a plain string, so an empty one
+ * survives the schema and is not a binding. Counting it would name a leaf no session is attached
+ * to, and a reveal that adopted that tab would show nothing.
+ */
+function collectOwnedLeafIds(layout: TerminalLayoutSnapshot): Set<string> {
+  if (layout.root) {
+    return new Set(collectLeafIdsInOrder(layout.root))
+  }
+  return new Set(
+    Object.entries(layout.ptyIdsByLeafId ?? {})
+      .filter(([, ptyId]) => Boolean(ptyId))
+      .map(([leafId]) => leafId)
+  )
+}
+
 /** The leaf a tab's layout binds to `ptyId`, or null when no leaf it owns holds that binding. */
 function findLayoutBoundLeafId(
   state: TerminalPtyPaneOwnerState,

src/renderer/src/lib/terminal-reveal-leaf-owner-lookup.test.ts

@@ -1,6 +1,6 @@
 // Which tab owns a leaf id decides whether a reveal adopts a pane or mints a second one
 // (STA-7961). Two layouts can name the same leaf: one that still mounts it, and one left
-// holding the id by a detach or by the hydration self-heal.
+// holding the id by a detach.
 import { describe, expect, it } from 'vitest'
 import { findTerminalTabIdBindingLeafId } from './terminal-reveal-tab-adoption'
 import type { AppState } from '@/store/types'
@@ -47,7 +47,7 @@ describe('findTerminalTabIdBindingLeafId', () => {
   })
 
   it('prefers the tab that binds the leaf over one that only carries it unbound', () => {
-    // The hydration self-heal unbinds the losing single-leaf tab but leaves the id in its tree.
+    // A pane keeps its leaf in the tree after its PTY exits, so the id outlives the binding.
     const bound = layout(leaf(SHARED_LEAF_ID), { [SHARED_LEAF_ID]: 'pty-a' })
     const unbound = layout(leaf(SHARED_LEAF_ID))
 

src/renderer/src/lib/terminal-reveal-tab-adoption.ts

@@ -15,8 +15,8 @@ export type TerminalRevealTabAdoption =
   | { kind: 'mint' }
 
 /**
- * The tab whose layout owns a leaf id. Bound-and-in-tree beats in-tree-unbound, because the
- * hydration self-heal leaves a losing single-leaf tab carrying its leaf with no session to adopt.
+ * The tab whose layout owns a leaf id. Bound-and-in-tree beats in-tree-unbound, because a pane
+ * keeps its leaf after its PTY exits or is cleared, and such a tab has no session to adopt.
  * Every layout is scanned, including ones whose row is gone: a leaf id is a pane identity for its
  * lifetime, and re-minting one an orphan layout still holds is how the STA-7961 pair was created.
  */