diff --git a/src/hooks/anthropic-context-window-limit-recovery/deduplication-recovery.ts b/src/hooks/anthropic-context-window-limit-recovery/deduplication-recovery.ts
new file mode 100644
index 000000000..d7cb0314e
--- /dev/null
+++ b/src/hooks/anthropic-context-window-limit-recovery/deduplication-recovery.ts
@@ -0,0 +1,71 @@
+import type { ParsedTokenLimitError } from "./types"
+import type { ExperimentalConfig } from "../../config"
+import type { DeduplicationConfig } from "./pruning-deduplication"
+import type { PruningState } from "./pruning-types"
+import { executeDeduplication } from "./pruning-deduplication"
+import { truncateToolOutputsByCallId } from "./pruning-tool-output-truncation"
+import { log } from "../../shared/logger"
+
+function createPruningState(): PruningState {
+  return {
+    toolIdsToPrune: new Set<string>(),
+    currentTurn: 0,
+    fileOperations: new Map(),
+    toolSignatures: new Map(),
+    erroredTools: new Map(),
+  }
+}
+
+function isPromptTooLongError(parsed: ParsedTokenLimitError): boolean {
+  return !parsed.errorType.toLowerCase().includes("non-empty content")
+}
+
+function getDeduplicationPlan(
+  experimental?: ExperimentalConfig,
+): { config: DeduplicationConfig; protectedTools: Set<string> } | null {
+  const pruningConfig = experimental?.dynamic_context_pruning
+  if (!pruningConfig?.enabled) return null
+
+  const deduplicationEnabled = pruningConfig.strategies?.deduplication?.enabled
+  if (deduplicationEnabled === false) return null
+
+  const protectedTools = new Set(pruningConfig.protected_tools ?? [])
+  return {
+    config: {
+      enabled: true,
+      protectedTools: pruningConfig.protected_tools ?? [],
+    },
+    protectedTools,
+  }
+}
+
+export async function attemptDeduplicationRecovery(
+  sessionID: string,
+  parsed: ParsedTokenLimitError,
+  experimental: ExperimentalConfig | undefined,
+): Promise<void> {
+  if (!isPromptTooLongError(parsed)) return
+
+  const plan = getDeduplicationPlan(experimental)
+  if (!plan) return
+
+  const pruningState = createPruningState()
+  const prunedCount = executeDeduplication(
+    sessionID,
+    pruningState,
+    plan.config,
+    plan.protectedTools,
+  )
+  const { truncatedCount } = truncateToolOutputsByCallId(
+    sessionID,
+    pruningState.toolIdsToPrune,
+  )
+
+  if (prunedCount > 0 || truncatedCount > 0) {
+    log("[auto-compact] deduplication recovery applied", {
+      sessionID,
+      prunedCount,
+      truncatedCount,
+    })
+  }
+}
diff --git a/src/hooks/anthropic-context-window-limit-recovery/pruning-tool-output-truncation.ts b/src/hooks/anthropic-context-window-limit-recovery/pruning-tool-output-truncation.ts
new file mode 100644
index 000000000..3958724a9
--- /dev/null
+++ b/src/hooks/anthropic-context-window-limit-recovery/pruning-tool-output-truncation.ts
@@ -0,0 +1,92 @@
+import { existsSync, readdirSync, readFileSync } from "node:fs"
+import { join } from "node:path"
+import { getOpenCodeStorageDir } from "../../shared/data-path"
+import { truncateToolResult } from "./storage"
+import { log } from "../../shared/logger"
+
+interface StoredToolPart {
+  type?: string
+  callID?: string
+  truncated?: boolean
+  state?: {
+    output?: string
+  }
+}
+
+const OPENCODE_STORAGE = getOpenCodeStorageDir()
+const MESSAGE_STORAGE = join(OPENCODE_STORAGE, "message")
+const PART_STORAGE = join(OPENCODE_STORAGE, "part")
+
+function getMessageDir(sessionID: string): string | null {
+  if (!existsSync(MESSAGE_STORAGE)) return null
+
+  const directPath = join(MESSAGE_STORAGE, sessionID)
+  if (existsSync(directPath)) return directPath
+
+  for (const dir of readdirSync(MESSAGE_STORAGE)) {
+    const sessionPath = join(MESSAGE_STORAGE, dir, sessionID)
+    if (existsSync(sessionPath)) return sessionPath
+  }
+
+  return null
+}
+
+function getMessageIds(sessionID: string): string[] {
+  const messageDir = getMessageDir(sessionID)
+  if (!messageDir) return []
+
+  const messageIds: string[] = []
+  for (const file of readdirSync(messageDir)) {
+    if (!file.endsWith(".json")) continue
+    messageIds.push(file.replace(".json", ""))
+  }
+
+  return messageIds
+}
+
+export function truncateToolOutputsByCallId(
+  sessionID: string,
+  callIds: Set<string>,
+): { truncatedCount: number } {
+  if (callIds.size === 0) return { truncatedCount: 0 }
+
+  const messageIds = getMessageIds(sessionID)
+  if (messageIds.length === 0) return { truncatedCount: 0 }
+
+  let truncatedCount = 0
+
+  for (const messageID of messageIds) {
+    const partDir = join(PART_STORAGE, messageID)
+    if (!existsSync(partDir)) continue
+
+    for (const file of readdirSync(partDir)) {
+      if (!file.endsWith(".json")) continue
+      const partPath = join(partDir, file)
+
+      try {
+        const content = readFileSync(partPath, "utf-8")
+        const part = JSON.parse(content) as StoredToolPart
+
+        if (part.type !== "tool" || !part.callID) continue
+        if (!callIds.has(part.callID)) continue
+        if (!part.state?.output || part.truncated) continue
+
+        const result = truncateToolResult(partPath)
+        if (result.success) {
+          truncatedCount++
+        }
+      } catch {
+        continue
+      }
+    }
+  }
+
+  if (truncatedCount > 0) {
+    log("[auto-compact] pruned duplicate tool outputs", {
+      sessionID,
+      truncatedCount,
+    })
+  }
+
+  return { truncatedCount }
+}
diff --git a/src/hooks/anthropic-context-window-limit-recovery/recovery-deduplication.test.ts b/src/hooks/anthropic-context-window-limit-recovery/recovery-deduplication.test.ts
new file mode 100644
index 000000000..2b82051af
--- /dev/null
+++ b/src/hooks/anthropic-context-window-limit-recovery/recovery-deduplication.test.ts
@@ -0,0 +1,155 @@
+import { describe, test, expect, mock } from "bun:test"
+import type { PluginInput } from "@opencode-ai/plugin"
+import type { ExperimentalConfig } from "../../config"
+import { mkdtempSync, mkdirSync, rmSync, writeFileSync, readFileSync } from "node:fs"
+import { join } from "node:path"
+import { tmpdir } from "node:os"
+
+function createImmediateTimeouts(): () => void {
+  const originalSetTimeout = globalThis.setTimeout
+  const originalClearTimeout = globalThis.clearTimeout
+
+  globalThis.setTimeout = ((callback: (...args: unknown[]) => void, _delay?: number, ...args: unknown[]) => {
+    callback(...args)
+    return 0 as unknown as ReturnType<typeof setTimeout>
+  }) as typeof setTimeout
+
+  globalThis.clearTimeout = ((_: ReturnType<typeof setTimeout>) => {}) as typeof clearTimeout
+
+  return () => {
+    globalThis.setTimeout = originalSetTimeout
+    globalThis.clearTimeout = originalClearTimeout
+  }
+}
+
+function writeJson(filePath: string, data: unknown): void {
+  writeFileSync(filePath, JSON.stringify(data, null, 2))
+}
+
+describe("createAnthropicContextWindowLimitRecoveryHook", () => {
+  test("attempts deduplication recovery when compaction hits prompt too long errors", async () => {
+    const restoreTimeouts = createImmediateTimeouts()
+    const originalDataHome = process.env.XDG_DATA_HOME
+    const tempHome = mkdtempSync(join(tmpdir(), "omo-context-"))
+    process.env.XDG_DATA_HOME = tempHome
+
+    const storageRoot = join(tempHome, "opencode", "storage")
+    const messageDir = join(storageRoot, "message", "session-96")
+    const partDir = join(storageRoot, "part", "message-1")
+    const partDirTwo = join(storageRoot, "part", "message-2")
+
+    mkdirSync(messageDir, { recursive: true })
+    mkdirSync(partDir, { recursive: true })
+    mkdirSync(partDirTwo, { recursive: true })
+
+    writeJson(join(messageDir, "message-1.json"), {
+      parts: [
+        {
+          type: "tool",
+          callID: "call-1",
+          tool: "read",
+          state: { input: { filePath: "/tmp/a.txt" } },
+        },
+      ],
+    })
+
+    writeJson(join(messageDir, "message-2.json"), {
+      parts: [
+        {
+          type: "tool",
+          callID: "call-2",
+          tool: "read",
+          state: { input: { filePath: "/tmp/a.txt" } },
+        },
+      ],
+    })
+
+    writeJson(join(partDir, "part-1.json"), {
+      id: "part-1",
+      sessionID: "session-96",
+      messageID: "message-1",
+      type: "tool",
+      callID: "call-1",
+      tool: "read",
+      state: {
+        status: "completed",
+        input: { filePath: "/tmp/a.txt" },
+        output: "duplicate output",
+      },
+    })
+
+    writeJson(join(partDirTwo, "part-2.json"), {
+      id: "part-2",
+      sessionID: "session-96",
+      messageID: "message-2",
+      type: "tool",
+      callID: "call-2",
+      tool: "read",
+      state: {
+        status: "completed",
+        input: { filePath: "/tmp/a.txt" },
+        output: "latest output",
+      },
+    })
+
+    const experimental = {
+      dynamic_context_pruning: {
+        enabled: true,
+        strategies: {
+          deduplication: { enabled: true },
+        },
+      },
+    } satisfies ExperimentalConfig
+
+    let resolveSummarize: (() => void) | null = null
+    const summarizePromise = new Promise<void>((resolve) => {
+      resolveSummarize = resolve
+    })
+
+    const mockClient = {
+      session: {
+        messages: mock(() => Promise.resolve({ data: [] })),
+        summarize: mock(() => summarizePromise),
+        revert: mock(() => Promise.resolve()),
+        prompt_async: mock(() => Promise.resolve()),
+      },
+      tui: {
+        showToast: mock(() => Promise.resolve()),
+      },
+    }
+
+    try {
+      const { createAnthropicContextWindowLimitRecoveryHook } = await import("./recovery-hook")
+      const ctx = { client: mockClient, directory: "/tmp" } as PluginInput
+      const hook = createAnthropicContextWindowLimitRecoveryHook(ctx, { experimental })
+
+      // given - initial token limit error schedules compaction
+      await hook.event({
+        event: {
+          type: "session.error",
+          properties: { sessionID: "session-96", error: "prompt is too long" },
+        },
+      })
+
+      // when - compaction hits another prompt-too-long error
+      await hook.event({
+        event: {
+          type: "session.error",
+          properties: { sessionID: "session-96", error: "prompt is too long" },
+        },
+      })
+
+      // then - duplicate tool output is truncated
+      const prunedPart = JSON.parse(
+        readFileSync(join(partDir, "part-1.json"), "utf-8"),
+      ) as { truncated?: boolean }
+
+      expect(prunedPart.truncated).toBe(true)
+    } finally {
+      if (resolveSummarize) resolveSummarize()
+      restoreTimeouts()
+      process.env.XDG_DATA_HOME = originalDataHome
+      rmSync(tempHome, { recursive: true, force: true })
+    }
+  })
+})
diff --git a/src/hooks/anthropic-context-window-limit-recovery/recovery-hook.ts b/src/hooks/anthropic-context-window-limit-recovery/recovery-hook.ts
index 62adbd9e1..f4bcb0f25 100644
--- a/src/hooks/anthropic-context-window-limit-recovery/recovery-hook.ts
+++ b/src/hooks/anthropic-context-window-limit-recovery/recovery-hook.ts
@@ -3,6 +3,7 @@ import type { AutoCompactState, ParsedTokenLimitError } from "./types"
 import type { ExperimentalConfig } from "../../config"
 import { parseAnthropicTokenLimitError } from "./parser"
 import { executeCompact, getLastAssistant } from "./executor"
+import { attemptDeduplicationRecovery } from "./deduplication-recovery"
 import { log } from "../../shared/logger"
 
 export interface AnthropicContextWindowLimitRecoveryOptions {
@@ -56,6 +57,7 @@ export function createAnthropicContextWindowLimitRecoveryHook(
         autoCompactState.errorDataBySession.set(sessionID, parsed)
 
         if (autoCompactState.compactionInProgress.has(sessionID)) {
+          await attemptDeduplicationRecovery(sessionID, parsed, experimental)
           return
         }