From 48dd3fba5550834d06dfcdbff1a0013e4b9bc0c5 Mon Sep 17 00:00:00 2001
From: Brennan Benson <79079362+brennanb2025@users.noreply.github.com>
Date: Wed, 16 Sep 2026 17:19:49 -0700
Subject: [PATCH] fix(native-chat): fence command execution after recovery

---
 ...d-conversation-command-concurrency.test.ts | 26 +++++++++++++++++++
 ...ructured-conversation-command-execution.ts | 24 ++++++++---------
 2 files changed, 37 insertions(+), 13 deletions(-)

diff --git a/src/main/native-chat/agent-session-wire/structured-conversation-command-concurrency.test.ts b/src/main/native-chat/agent-session-wire/structured-conversation-command-concurrency.test.ts
index 5f6c598658f..11261808437 100644
--- a/src/main/native-chat/agent-session-wire/structured-conversation-command-concurrency.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-conversation-command-concurrency.test.ts
@@ -127,6 +127,32 @@ describe('host conversation command concurrency', () => {
     )
   })
 
+  it('does not start provider work after recovery advances during event flushing', async () => {
+    await host.hold(HOST_TEST_SESSION, 'conversation-surface')
+    const flush = Promise.withResolvers<void>()
+    const flushing = Promise.withResolvers<void>()
+    vi.spyOn(host, 'flushStreamedEvents').mockImplementationOnce(() => {
+      flushing.resolve()
+      return flush.promise
+    })
+    const running = host.conversationCommand(CALLER, commandParams('compact'))
+    await flushing.promise
+    const fence = store.getRecord(HOST_TEST_SESSION)!.lease.runtimeFence
+
+    await host.handleAdapterEvent({
+      type: 'ended',
+      sessionId: HOST_TEST_SESSION,
+      reason: 'provider exited',
+      cause: 'unexpected-exit',
+      fence,
+      acquisitionGeneration: 'generation-1'
+    })
+    flush.resolve()
+
+    await expect(running).resolves.toMatchObject({ ok: true, value: { state: 'unknown' } })
+    expect(compact).not.toHaveBeenCalled()
+  })
+
   it('retires a provider completion that arrives after recovery advances the generation', async () => {
     await host.hold(HOST_TEST_SESSION, 'conversation-surface')
     const completion = Promise.withResolvers<Record<string, never>>()
diff --git a/src/main/native-chat/agent-session-wire/structured-conversation-command-execution.ts b/src/main/native-chat/agent-session-wire/structured-conversation-command-execution.ts
index efa65c92eee..1134bcac348 100644
--- a/src/main/native-chat/agent-session-wire/structured-conversation-command-execution.ts
+++ b/src/main/native-chat/agent-session-wire/structured-conversation-command-execution.ts
@@ -16,7 +16,7 @@ import {
   publishConversationCommandLifecycle
 } from './structured-conversation-command-lifecycle'
 import type { StructuredAgentSessionMutationContext } from './structured-agent-session-host-mutations'
-import type { StructuredAgentSessionHost } from './structured-agent-session-host'
+import type { StructuredAgentSessionHost as Host } from './structured-agent-session-host'
 
 type ExecutionOwner = {
   isCurrent: (entry: PendingConversationCommand) => boolean
@@ -24,16 +24,12 @@ type ExecutionOwner = {
   settleWaiter: (entry: PendingConversationCommand, result: ConversationCommandResult) => void
   report: (entry: PendingConversationCommand, error: unknown) => void
 }
-
-const STALE_COMMAND_COMPLETION = new Error('Conversation operation became stale after recovery.')
+type ExecutionHost = Pick<Host, 'attach' | 'close' | 'flushStreamedEvents' | 'hasSession'>
 
 export class StructuredConversationCommandExecution {
   constructor(
     private readonly context: () => StructuredAgentSessionMutationContext,
-    private readonly host: Pick<
-      StructuredAgentSessionHost,
-      'attach' | 'close' | 'flushStreamedEvents' | 'hasSession'
-    >,
+    private readonly host: ExecutionHost,
     private readonly owner: ExecutionOwner
   ) {}
 
@@ -46,7 +42,8 @@ export class StructuredConversationCommandExecution {
     try {
       await this.publishLifecycle(entry, execution.prepared, 'running')
       await this.host.flushStreamedEvents(execution.turn.sessionId)
-      if (!this.owner.isCurrent(entry)) {
+      if (!this.canSettle(entry, execution)) {
+        await this.markUnknown(entry, new Error(CONVERSATION_COMMAND_ABANDONED), true)
         return
       }
       providerMaySettleLate = entry.command === 'compact'
@@ -132,7 +129,8 @@ export class StructuredConversationCommandExecution {
         return
       }
     }
-    if (!this.owner.isCurrent(entry)) {
+    if (!this.canSettle(entry, execution)) {
+      await this.markUnknown(entry, new Error(CONVERSATION_COMMAND_ABANDONED), true)
       return
     }
     if (effectiveOptions) {
@@ -142,7 +140,8 @@ export class StructuredConversationCommandExecution {
         }
       })
     }
-    if (!this.owner.isCurrent(entry)) {
+    if (!this.canSettle(entry, execution)) {
+      await this.markUnknown(entry, new Error(CONVERSATION_COMMAND_ABANDONED), true)
       return
     }
     const replacementSessionId = execution.prepared.replacementSessionId!
@@ -288,9 +287,8 @@ export class StructuredConversationCommandExecution {
     entry: PendingConversationCommand,
     execution: PreparedConversationCommand
   ): boolean {
-    const command = this.context().deps.store.getRecord(
-      execution.turn.sessionId
-    )?.conversationCommand
+    const store = this.context().deps.store
+    const command = store.getRecord(execution.turn.sessionId)?.conversationCommand
     return this.ownsExecution(entry, execution) && command?.phase === 'prepared'
   }