Merge pull request #2668 from MoerAI/fix/session-degradation-detection

fix(session): detect post-compaction no-text degradation and trigger recovery (fixes #2232)

src/hooks/preemptive-compaction-degradation-monitor.ts

@@ -0,0 +1,188 @@
+import type { OhMyOpenCodeConfig } from "../config"
+import { log } from "../shared/logger"
+import { resolveNoTextTailFromSession } from "./preemptive-compaction-no-text-tail"
+import { resolveCompactionModel } from "./shared/compaction-model-resolver"
+
+const PREEMPTIVE_COMPACTION_TIMEOUT_MS = 120_000
+const POST_COMPACTION_MONITOR_COUNT = 5
+const POST_COMPACTION_NO_TEXT_THRESHOLD = 3
+
+declare function setTimeout(handler: () => void, timeout?: number): unknown
+declare function clearTimeout(timeoutID: unknown): void
+
+interface CompactionTargetState {
+  providerID: string
+  modelID: string
+}
+
+interface ClientLike {
+  session: {
+    summarize: (input: {
+      path: { id: string }
+      body: { providerID: string; modelID: string }
+      query: { directory: string }
+    }) => Promise<unknown>
+    messages: (input: {
+      path: { id: string }
+      query?: { directory: string }
+    }) => Promise<unknown>
+  }
+  tui: {
+    showToast: (input: {
+      body: {
+        title: string
+        message: string
+        variant: "warning"
+        duration: number
+      }
+    }) => Promise<unknown>
+  }
+}
+
+export interface AssistantCompactionMessageInfo {
+  sessionID: string
+  id?: string
+}
+
+async function withTimeout<TValue>(
+  promise: Promise<TValue>,
+  timeoutMs: number,
+  errorMessage: string,
+): Promise<TValue> {
+  let timeoutID: unknown
+
+  const timeoutPromise = new Promise<never>((_, reject) => {
+    timeoutID = setTimeout(() => {
+      reject(new Error(errorMessage))
+    }, timeoutMs)
+  })
+
+  return await Promise.race([promise, timeoutPromise]).finally(() => {
+    clearTimeout(timeoutID)
+  })
+}
+
+export function createPostCompactionDegradationMonitor(args: {
+  client: ClientLike
+  directory: string
+  pluginConfig: OhMyOpenCodeConfig
+  tokenCache: Map<string, CompactionTargetState>
+  compactionInProgress: Set<string>
+}) {
+  const { client, directory, pluginConfig, tokenCache, compactionInProgress } = args
+  const postCompactionRemaining = new Map<string, number>()
+  const postCompactionNoTextStreak = new Map<string, number>()
+  const postCompactionRecoveryTriggered = new Set<string>()
+  const postCompactionEpoch = new Map<string, number>()
+
+  const clear = (sessionID: string): void => {
+    postCompactionRemaining.delete(sessionID)
+    postCompactionNoTextStreak.delete(sessionID)
+    postCompactionRecoveryTriggered.delete(sessionID)
+    postCompactionEpoch.delete(sessionID)
+  }
+
+  const onSessionCompacted = (sessionID: string): void => {
+    const nextEpoch = (postCompactionEpoch.get(sessionID) ?? 0) + 1
+    postCompactionEpoch.set(sessionID, nextEpoch)
+    postCompactionRemaining.set(sessionID, POST_COMPACTION_MONITOR_COUNT)
+    postCompactionNoTextStreak.set(sessionID, 0)
+    postCompactionRecoveryTriggered.delete(sessionID)
+  }
+
+  const triggerRecovery = async (sessionID: string): Promise<void> => {
+    if (postCompactionRecoveryTriggered.has(sessionID) || compactionInProgress.has(sessionID)) return
+
+    const cached = tokenCache.get(sessionID)
+    if (!cached?.modelID) {
+      log("[preemptive-compaction] No-text tail detected but compaction model is unavailable", { sessionID })
+      return
+    }
+
+    postCompactionRecoveryTriggered.add(sessionID)
+    compactionInProgress.add(sessionID)
+    const recoveryEpoch = postCompactionEpoch.get(sessionID) ?? 0
+
+    try {
+      const { providerID: targetProviderID, modelID: targetModelID } = resolveCompactionModel(
+        pluginConfig,
+        sessionID,
+        cached.providerID,
+        cached.modelID,
+      )
+
+      await client.tui
+        .showToast({
+          body: {
+            title: "Session Degradation Detected",
+            message: "Detected repeated no-text assistant responses after compaction. Retrying compaction recovery.",
+            variant: "warning",
+            duration: 5000,
+          },
+        })
+        .catch(() => {})
+
+      await withTimeout(
+        client.session.summarize({
+          path: { id: sessionID },
+          body: { providerID: targetProviderID, modelID: targetModelID },
+          query: { directory },
+        }),
+        PREEMPTIVE_COMPACTION_TIMEOUT_MS,
+        `Compaction recovery summarize timed out after ${PREEMPTIVE_COMPACTION_TIMEOUT_MS}ms`,
+      )
+
+      log("[preemptive-compaction] Triggered recovery after post-compaction no-text tail", { sessionID })
+    } catch (error) {
+      log("[preemptive-compaction] Failed to recover post-compaction no-text tail", {
+        sessionID,
+        error: String(error),
+      })
+    } finally {
+      compactionInProgress.delete(sessionID)
+      if ((postCompactionEpoch.get(sessionID) ?? 0) === recoveryEpoch) {
+        clear(sessionID)
+      }
+    }
+  }
+
+  const onAssistantMessageUpdated = async (info: AssistantCompactionMessageInfo): Promise<void> => {
+    const remaining = postCompactionRemaining.get(info.sessionID)
+    if (!remaining || remaining <= 0) return
+
+    if (remaining === 1) {
+      postCompactionRemaining.delete(info.sessionID)
+    } else {
+      postCompactionRemaining.set(info.sessionID, remaining - 1)
+    }
+
+    const isNoTextTail = await resolveNoTextTailFromSession({
+      client,
+      sessionID: info.sessionID,
+      messageID: info.id,
+      directory,
+    })
+
+    if (!isNoTextTail) {
+      postCompactionNoTextStreak.set(info.sessionID, 0)
+      return
+    }
+
+    const nextStreak = (postCompactionNoTextStreak.get(info.sessionID) ?? 0) + 1
+    postCompactionNoTextStreak.set(info.sessionID, nextStreak)
+
+    if (nextStreak >= POST_COMPACTION_NO_TEXT_THRESHOLD) {
+      log("[preemptive-compaction] Detected post-compaction no-text tail pattern", {
+        sessionID: info.sessionID,
+        streak: nextStreak,
+      })
+      await triggerRecovery(info.sessionID)
+    }
+  }
+
+  return {
+    clear,
+    onSessionCompacted,
+    onAssistantMessageUpdated,
+  }
+}

src/hooks/preemptive-compaction-no-text-tail.ts

@@ -0,0 +1,70 @@
+import { normalizeSDKResponse } from "../shared/normalize-sdk-response"
+
+const STEP_ONLY_TYPES = new Set(["step-start", "step-finish"])
+
+interface MessagePart {
+  type?: unknown
+  text?: unknown
+}
+
+interface SessionMessage {
+  info?: {
+    id?: string
+    role?: string
+  }
+  parts?: MessagePart[]
+}
+
+export function isStepOnlyNoTextParts(parts: unknown): boolean {
+  if (!Array.isArray(parts) || parts.length === 0) return false
+
+  return parts.every((part) => {
+    const type = (part as MessagePart | undefined)?.type
+    if (typeof type !== "string") return false
+    if (!STEP_ONLY_TYPES.has(type)) return false
+
+    const text = (part as MessagePart | undefined)?.text
+    if (typeof text === "string" && text.trim().length > 0) return false
+    return true
+  })
+}
+
+function findMessageByID(messages: SessionMessage[], messageID?: string): SessionMessage | undefined {
+  if (!messageID) return undefined
+  return messages.find((message) => message.info?.id === messageID)
+}
+
+export async function resolveNoTextTailFromSession(args: {
+  client: {
+    session: {
+      messages: (input: {
+        path: { id: string }
+        query?: { directory: string }
+      }) => Promise<unknown>
+    }
+  }
+  sessionID: string
+  messageID?: string
+  directory: string
+}): Promise<boolean> {
+  const { client, sessionID, messageID, directory } = args
+
+  try {
+    const response = await client.session.messages({
+      path: { id: sessionID },
+      query: { directory },
+    })
+
+    const messages = normalizeSDKResponse(response, [] as SessionMessage[], {
+      preferResponseOnMissingData: true,
+    })
+    if (!Array.isArray(messages) || messages.length === 0) return false
+
+    const target = findMessageByID(messages, messageID) ?? messages[messages.length - 1]
+    if (target.info?.role !== "assistant") return false
+
+    return isStepOnlyNoTextParts(target.parts)
+  } catch {
+    return false
+  }
+}

src/hooks/preemptive-compaction.degradation-monitor.test.ts

@@ -0,0 +1,138 @@
+import { beforeEach, describe, expect, it, mock } from "bun:test"
+
+const logMock = mock(() => {})
+
+mock.module("../shared/logger", () => ({
+  log: logMock,
+}))
+
+const { createPreemptiveCompactionHook } = await import("./preemptive-compaction")
+
+function createMockCtx() {
+  return {
+    client: {
+      session: {
+        messages: mock(() => Promise.resolve({ data: [] })),
+        summarize: mock(() => Promise.resolve({})),
+      },
+      tui: {
+        showToast: mock(() => Promise.resolve({})),
+      },
+    },
+    directory: "/tmp/test",
+  }
+}
+
+function buildAssistantUpdate(input: {
+  sessionID: string
+  id: string
+  parts: unknown[]
+}): {
+  event: {
+    type: string
+    properties: {
+      info: {
+        id: string
+        role: string
+        sessionID: string
+        providerID: string
+        modelID: string
+        finish: boolean
+        tokens: { input: number; output: number; reasoning: number; cache: { read: number; write: number } }
+        parts: unknown[]
+      }
+    }
+  }
+} {
+  return {
+    event: {
+      type: "message.updated",
+      properties: {
+        info: {
+          id: input.id,
+          role: "assistant",
+          sessionID: input.sessionID,
+          providerID: "anthropic",
+          modelID: "claude-sonnet-4-6",
+          finish: true,
+          tokens: { input: 1000, output: 10, reasoning: 0, cache: { read: 0, write: 0 } },
+          parts: input.parts,
+        },
+      },
+    },
+  }
+}
+
+describe("preemptive-compaction post-compaction degradation monitor", () => {
+  beforeEach(() => {
+    logMock.mockClear()
+  })
+
+  it("triggers recovery summarize after three consecutive no-text tail messages", async () => {
+    const ctx = createMockCtx()
+    const hook = createPreemptiveCompactionHook(ctx as never, {} as never)
+    const sessionID = "ses_tail_recovery"
+
+    await hook.event({
+      event: {
+        type: "session.compacted",
+        properties: { sessionID },
+      },
+    })
+
+    const stepOnlyParts = [{ type: "step-start" }, { type: "step-finish" }]
+
+    await hook.event(buildAssistantUpdate({ sessionID, id: "msg_1", parts: stepOnlyParts }))
+    await hook.event(buildAssistantUpdate({ sessionID, id: "msg_2", parts: stepOnlyParts }))
+    await hook.event(buildAssistantUpdate({ sessionID, id: "msg_3", parts: stepOnlyParts }))
+
+    expect(ctx.client.session.summarize).toHaveBeenCalledTimes(1)
+    expect(ctx.client.tui.showToast).toHaveBeenCalledTimes(1)
+    expect(logMock).toHaveBeenCalledWith(
+      "[preemptive-compaction] Detected post-compaction no-text tail pattern",
+      {
+        sessionID,
+        streak: 3,
+      },
+    )
+  })
+
+  it("resets no-text streak when assistant emits text content", async () => {
+    const ctx = createMockCtx()
+    const hook = createPreemptiveCompactionHook(ctx as never, {} as never)
+    const sessionID = "ses_tail_reset"
+
+    await hook.event({
+      event: {
+        type: "session.compacted",
+        properties: { sessionID },
+      },
+    })
+
+    await hook.event(buildAssistantUpdate({
+      sessionID,
+      id: "msg_1",
+      parts: [{ type: "step-start" }, { type: "step-finish" }],
+    }))
+
+    await hook.event(buildAssistantUpdate({
+      sessionID,
+      id: "msg_2",
+      parts: [{ type: "text", text: "Recovered response" }],
+    }))
+
+    await hook.event(buildAssistantUpdate({
+      sessionID,
+      id: "msg_3",
+      parts: [{ type: "step-start" }, { type: "step-finish" }],
+    }))
+
+    await hook.event(buildAssistantUpdate({
+      sessionID,
+      id: "msg_4",
+      parts: [{ type: "step-start" }, { type: "step-finish" }],
+    }))
+
+    expect(ctx.client.session.summarize).not.toHaveBeenCalled()
+  })
+})

src/hooks/preemptive-compaction.ts

@@ -6,10 +6,14 @@ import {
 } from "../shared/context-limit-resolver"
 
 import { resolveCompactionModel } from "./shared/compaction-model-resolver"
-const PREEMPTIVE_COMPACTION_TIMEOUT_MS = 120_000
+import { createPostCompactionDegradationMonitor } from "./preemptive-compaction-degradation-monitor"
 
+const PREEMPTIVE_COMPACTION_TIMEOUT_MS = 120_000
 const PREEMPTIVE_COMPACTION_THRESHOLD = 0.78
 
+declare function setTimeout(handler: () => void, timeout?: number): unknown
+declare function clearTimeout(timeoutID: unknown): void
+
 interface TokenInfo {
   input: number
   output: number
@@ -28,7 +32,7 @@ async function withTimeout<TValue>(
   timeoutMs: number,
   errorMessage: string,
 ): Promise<TValue> {
-  let timeoutID: ReturnType<typeof setTimeout> | undefined
+  let timeoutID: unknown
 
   const timeoutPromise = new Promise<never>((_, reject) => {
     timeoutID = setTimeout(() => {
@@ -37,9 +41,7 @@ async function withTimeout<TValue>(
   })
 
   return await Promise.race([promise, timeoutPromise]).finally(() => {
-    if (timeoutID !== undefined) {
+    clearTimeout(timeoutID)
-      clearTimeout(timeoutID)
-    }
   })
 }
 
@@ -68,6 +70,14 @@ export function createPreemptiveCompactionHook(
   const compactedSessions = new Set<string>()
   const tokenCache = new Map<string, CachedCompactionState>()
 
+  const postCompactionMonitor = createPostCompactionDegradationMonitor({
+    client: ctx.client,
+    directory: ctx.directory,
+    pluginConfig,
+    tokenCache,
+    compactionInProgress,
+  })
+
   const toolExecuteAfter = async (
     input: { tool: string; sessionID: string; callID: string },
     _output: { title: string; output: string; metadata: unknown }
@@ -92,14 +102,9 @@ export function createPreemptiveCompactionHook(
       return
     }
 
-    const lastTokens = cached.tokens
+    const totalInputTokens = (cached.tokens.input ?? 0) + (cached.tokens.cache?.read ?? 0)
-    const totalInputTokens = (lastTokens?.input ?? 0) + (lastTokens?.cache?.read ?? 0)
     const usageRatio = totalInputTokens / actualLimit
-
+    if (usageRatio < PREEMPTIVE_COMPACTION_THRESHOLD || !cached.modelID) return
-    if (usageRatio < PREEMPTIVE_COMPACTION_THRESHOLD) return
-
-    const modelID = cached.modelID
-    if (!modelID) return
 
     compactionInProgress.add(sessionID)
 
@@ -108,7 +113,7 @@ export function createPreemptiveCompactionHook(
         pluginConfig,
         sessionID,
         cached.providerID,
-        modelID
+        cached.modelID,
       )
 
       await withTimeout(
@@ -133,17 +138,28 @@ export function createPreemptiveCompactionHook(
     const props = event.properties as Record<string, unknown> | undefined
 
     if (event.type === "session.deleted") {
-      const sessionInfo = props?.info as { id?: string } | undefined
+      const sessionID = (props?.info as { id?: string } | undefined)?.id
-      if (sessionInfo?.id) {
+      if (sessionID) {
-        compactionInProgress.delete(sessionInfo.id)
+        compactionInProgress.delete(sessionID)
-        compactedSessions.delete(sessionInfo.id)
+        compactedSessions.delete(sessionID)
-        tokenCache.delete(sessionInfo.id)
+        tokenCache.delete(sessionID)
+        postCompactionMonitor.clear(sessionID)
+      }
+      return
+    }
+
+    if (event.type === "session.compacted") {
+      const sessionID = (props?.sessionID as string | undefined)
+        ?? (props?.info as { id?: string } | undefined)?.id
+      if (sessionID) {
+        postCompactionMonitor.onSessionCompacted(sessionID)
       }
       return
     }
 
     if (event.type === "message.updated") {
       const info = props?.info as {
+        id?: string
         role?: string
         sessionID?: string
         providerID?: string
@@ -152,15 +168,21 @@ export function createPreemptiveCompactionHook(
         tokens?: TokenInfo
       } | undefined
 
-      if (!info || info.role !== "assistant" || !info.finish) return
+      if (!info || info.role !== "assistant" || !info.finish || !info.sessionID) return
-      if (!info.sessionID || !info.providerID || !info.tokens) return
 
-      tokenCache.set(info.sessionID, {
+      if (info.providerID && info.tokens) {
-        providerID: info.providerID,
+        tokenCache.set(info.sessionID, {
-        modelID: info.modelID ?? "",
+          providerID: info.providerID,
-        tokens: info.tokens,
+          modelID: info.modelID ?? "",
-      })
+          tokens: info.tokens,
+        })
+      }
       compactedSessions.delete(info.sessionID)
+
+      await postCompactionMonitor.onAssistantMessageUpdated({
+        sessionID: info.sessionID,
+        id: info.id,
+      })
     }
   }