fix(recovery): ignore empty summary-only assistant messages

src/hooks/anthropic-context-window-limit-recovery/message-builder.ts

@@ -158,7 +158,7 @@ export async function getLastAssistant(
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   client: any,
   directory: string,
-): Promise<Record<string, unknown> | null> {
+): Promise<{ info: Record<string, unknown>; hasContent: boolean } | null> {
   try {
     const resp = await (client as Client).session.messages({
       path: { id: sessionID },
@@ -175,7 +175,15 @@ export async function getLastAssistant(
       return info?.role === "assistant"
     })
     if (!last) return null
-    return (last as { info?: Record<string, unknown> }).info ?? null
+
+    const message = last as SDKMessage & { info?: Record<string, unknown> }
+    const info = message.info
+    if (!info) return null
+
+    return {
+      info,
+      hasContent: messageHasContentFromSDK(message),
+    }
   } catch {
     return null
   }

src/hooks/anthropic-context-window-limit-recovery/recovery-hook.test.ts

@@ -6,8 +6,11 @@ import * as originalLogger from "../../shared/logger"
 
 const executeCompactMock = mock(async () => {})
 const getLastAssistantMock = mock(async () => ({
-  providerID: "anthropic",
-  modelID: "claude-sonnet-4-6",
+  info: {
+    providerID: "anthropic",
+    modelID: "claude-sonnet-4-6",
+  },
+  hasContent: true,
 }))
 const parseAnthropicTokenLimitErrorMock = mock(() => ({
   providerID: "anthropic",
@@ -115,4 +118,43 @@ describe("createAnthropicContextWindowLimitRecoveryHook", () => {
       restore()
     }
   })
+
+  test("does not treat empty summary assistant messages as successful compaction", async () => {
+    //#given
+    const { restore, getClearTimeoutCalls } = setupDelayedTimeoutMocks()
+    getLastAssistantMock.mockResolvedValueOnce({
+      info: {
+        summary: true,
+        providerID: "anthropic",
+        modelID: "claude-sonnet-4-6",
+      },
+      hasContent: false,
+    })
+    const { createAnthropicContextWindowLimitRecoveryHook } = await import("./recovery-hook")
+    const hook = createAnthropicContextWindowLimitRecoveryHook(createMockContext())
+
+    try {
+      //#when
+      await hook.event({
+        event: {
+          type: "session.error",
+          properties: { sessionID: "session-empty-summary", error: "prompt is too long" },
+        },
+      })
+
+      await hook.event({
+        event: {
+          type: "session.idle",
+          properties: { sessionID: "session-empty-summary" },
+        },
+      })
+
+      //#then
+      expect(getClearTimeoutCalls()).toEqual([1 as ReturnType<typeof setTimeout>])
+      expect(executeCompactMock).toHaveBeenCalledTimes(1)
+      expect(executeCompactMock.mock.calls[0]?.[0]).toBe("session-empty-summary")
+    } finally {
+      restore()
+    }
+  })
 })

src/hooks/anthropic-context-window-limit-recovery/recovery-hook.ts

@@ -72,8 +72,9 @@ export function createAnthropicContextWindowLimitRecoveryHook(
         }
 
         const lastAssistant = await getLastAssistant(sessionID, ctx.client, ctx.directory)
-        const providerID = parsed.providerID ?? (lastAssistant?.providerID as string | undefined)
-        const modelID = parsed.modelID ?? (lastAssistant?.modelID as string | undefined)
+        const lastAssistantInfo = lastAssistant?.info
+        const providerID = parsed.providerID ?? (lastAssistantInfo?.providerID as string | undefined)
+        const modelID = parsed.modelID ?? (lastAssistantInfo?.modelID as string | undefined)
 
         await ctx.client.tui
           .showToast({
@@ -136,14 +137,15 @@ export function createAnthropicContextWindowLimitRecoveryHook(
 
       const errorData = autoCompactState.errorDataBySession.get(sessionID)
       const lastAssistant = await getLastAssistant(sessionID, ctx.client, ctx.directory)
+      const lastAssistantInfo = lastAssistant?.info
 
-      if (lastAssistant?.summary === true) {
+      if (lastAssistantInfo?.summary === true && lastAssistant?.hasContent) {
         autoCompactState.pendingCompact.delete(sessionID)
         return
       }
 
-      const providerID = errorData?.providerID ?? (lastAssistant?.providerID as string | undefined)
-      const modelID = errorData?.modelID ?? (lastAssistant?.modelID as string | undefined)
+      const providerID = errorData?.providerID ?? (lastAssistantInfo?.providerID as string | undefined)
+      const modelID = errorData?.modelID ?? (lastAssistantInfo?.modelID as string | undefined)
 
       await ctx.client.tui
         .showToast({