fix: wire deduplication into compaction recovery for prompt-too-long errors (#96)

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

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 }
+}