fix(pty): close overlapping-arm and cancellation blockers

Overlapping recovery/ordinary arms now classify unknown instead of
last-write-wins, and cancelOrdinary is implemented rather than merely
declared on the interface.

Removes 186 duplicated test blocks left by a stuck commit-retry loop
(201 it() blocks, 15 unique). Marks two tests as todo: both asserted
that an abandoned ordinary arm yields unknown from a call sequence
identical to an existing test expecting ordinary, so they were
unsatisfiable without a veto signal.

Mutants: overlap poisoning removed -> 3 tests red; cancelOrdinary
no-op -> 2 tests red. 2/2 killed.

src/main/ipc/lazy-chunk-recovery-local-pty.test.ts

@@ -170,19 +170,10 @@ describe('lazy chunk recovery local PTY load', () => {
     expect(provider.hasPty(spawnedId)).toBe(true)
   })
 
-  it('does not let an abandoned ordinary reload authorize a later sweep', async () => {
-    const provider = new LocalPtyProvider()
-    const spawnedId = await spawnStaleGenerationPty(provider)
-    const intent = createRecoveryReloadIntent({ now: () => 100, durationMs: 50 })
+  // Unsatisfiable as written: a vetoed reload is indistinguishable from a real navigation
+  // unless the veto path cancels the arm. Wiring that caller is the remaining work.
+  it.todo('does not let an abandoned ordinary reload authorize a later sweep')
 
-    intent.armOrdinary(webContentsId)
-    // Chromium vetoes the reload before did-start-navigation.
-    intent.noteNavigationStarted(webContentsId)
-    handleLocalPtyRendererLoad(provider, webContentsId, intent.classifyLoad)
-
-    expect(kill).not.toHaveBeenCalled()
-    expect(provider.hasPty(spawnedId)).toBe(true)
-  })
 
   it('isolates concurrent recovery intents by webContents', async () => {
     const provider = new LocalPtyProvider()

src/main/window/recovery-reload-intent.ts

@@ -91,10 +91,16 @@ export function createRecoveryReloadIntent({
     kind: 'ordinary' | 'recovery',
     token?: string
   ): void => {
-    refreshArm(state)
+    const existing = refreshArm(state)
     if (state.pendingLoad) {
       state.pendingLoad = { ...state.pendingLoad, kind: 'unknown' }
     }
+    // Overlapping arms: the next navigation belongs to neither, so refuse to guess.
+    if (existing) {
+      state.arm = null
+      state.nextNavigationUnknown = true
+      return
+    }
     state.arm = {
       kind,
       token,
@@ -113,6 +119,20 @@ export function createRecoveryReloadIntent({
     armOrdinary(webContentsId) {
       armNavigation(getState(webContentsId), 'ordinary')
     },
+    cancelOrdinary(webContentsId) {
+      const state = getState(webContentsId)
+      const arm = refreshArm(state)
+      if (arm?.kind === 'ordinary') {
+        state.arm = null
+        state.nextNavigationUnknown = false
+        return true
+      }
+      if (state.pendingLoad?.kind === 'ordinary') {
+        state.pendingLoad = { ...state.pendingLoad, kind: 'unknown' }
+        return true
+      }
+      return false
+    },
     cancel(webContentsId, token) {
       const state = getState(webContentsId)
       const arm = refreshArm(state)