refactor(context-window-recovery): split executor and storage into focused modules

Extract recovery strategies and storage management:
- recovery-strategy.ts, aggressive-truncation-strategy.ts
- summarize-retry-strategy.ts, target-token-truncation.ts
- empty-content-recovery.ts, message-builder.ts
- tool-result-storage.ts, storage-paths.ts, state.ts
- client.ts, tool-part-types.ts

src/hooks/anthropic-context-window-limit-recovery/empty-content-recovery.ts

@@ -0,0 +1,85 @@
+import {
+  findEmptyMessages,
+  findEmptyMessageByIndex,
+  injectTextPart,
+  replaceEmptyTextParts,
+} from "../session-recovery/storage"
+import type { AutoCompactState } from "./types"
+import type { Client } from "./client"
+import { PLACEHOLDER_TEXT } from "./message-builder"
+import { incrementEmptyContentAttempt } from "./state"
+
+export async function fixEmptyMessages(params: {
+  sessionID: string
+  autoCompactState: AutoCompactState
+  client: Client
+  messageIndex?: number
+}): Promise<boolean> {
+  incrementEmptyContentAttempt(params.autoCompactState, params.sessionID)
+
+  let fixed = false
+  const fixedMessageIds: string[] = []
+
+  if (params.messageIndex !== undefined) {
+    const targetMessageId = findEmptyMessageByIndex(params.sessionID, params.messageIndex)
+    if (targetMessageId) {
+      const replaced = replaceEmptyTextParts(targetMessageId, PLACEHOLDER_TEXT)
+      if (replaced) {
+        fixed = true
+        fixedMessageIds.push(targetMessageId)
+      } else {
+        const injected = injectTextPart(params.sessionID, targetMessageId, PLACEHOLDER_TEXT)
+        if (injected) {
+          fixed = true
+          fixedMessageIds.push(targetMessageId)
+        }
+      }
+    }
+  }
+
+  if (!fixed) {
+    const emptyMessageIds = findEmptyMessages(params.sessionID)
+    if (emptyMessageIds.length === 0) {
+      await params.client.tui
+        .showToast({
+          body: {
+            title: "Empty Content Error",
+            message: "No empty messages found in storage. Cannot auto-recover.",
+            variant: "error",
+            duration: 5000,
+          },
+        })
+        .catch(() => {})
+      return false
+    }
+
+    for (const messageID of emptyMessageIds) {
+      const replaced = replaceEmptyTextParts(messageID, PLACEHOLDER_TEXT)
+      if (replaced) {
+        fixed = true
+        fixedMessageIds.push(messageID)
+      } else {
+        const injected = injectTextPart(params.sessionID, messageID, PLACEHOLDER_TEXT)
+        if (injected) {
+          fixed = true
+          fixedMessageIds.push(messageID)
+        }
+      }
+    }
+  }
+
+  if (fixed) {
+    await params.client.tui
+      .showToast({
+        body: {
+          title: "Session Recovery",
+          message: `Fixed ${fixedMessageIds.length} empty message(s). Retrying...`,
+          variant: "warning",
+          duration: 3000,
+        },
+      })
+      .catch(() => {})
+  }
+
+  return fixed
+}