fix: add proc.kill fallback when process group kill fails

fix: kill process group on timeout and handle stdin EPIPE
- Use detached process group (non-Windows) + process.kill(-pid) to kill the entire process tree, not just the outer shell wrapper - Add proc.stdin error listener to absorb EPIPE when child exits before stdin write completes
2026-02-22 15:06:09 +09:00 · 2026-02-22 15:06:09 +09:00 · 2026-02-22 15:06:09 +09:00 · 2026-02-22 15:06:09 +09:00 · 2026-02-22 14:50:59 +09:00 · 2026-02-22 14:46:59 +09:00
19 changed files with 1478 additions and 761 deletions
--- a/src/plugin/event.ts
+++ b/src/plugin/event.ts
@@ -1,53 +1,58 @@
-import type { OhMyOpenCodeConfig } from "../config"
-import type { PluginContext } from "./types"
+import type { OhMyOpenCodeConfig } from "../config";
+import type { PluginContext } from "./types";

 import {
  clearSessionAgent,
  getMainSessionID,
  getSessionAgent,
+  setMainSession,
  subagentSessions,
  syncSubagentSessions,
-  setMainSession,
  updateSessionAgent,
-} from "../features/claude-code-session-state"
-import { resetMessageCursor } from "../shared"
-import { lspManager } from "../tools"
-import { shouldRetryError } from "../shared/model-error-classifier"
-import { clearPendingModelFallback, clearSessionFallbackChain, setPendingModelFallback } from "../hooks/model-fallback/hook"
-import { log } from "../shared/logger"
-import { clearSessionModel, setSessionModel } from "../shared/session-model-state"
+} from "../features/claude-code-session-state";
+import {
+  clearPendingModelFallback,
+  clearSessionFallbackChain,
+  setPendingModelFallback,
+} from "../hooks/model-fallback/hook";
+import { resetMessageCursor } from "../shared";
+import { log } from "../shared/logger";
+import { shouldRetryError } from "../shared/model-error-classifier";
+import { clearSessionModel, setSessionModel } from "../shared/session-model-state";
+import { deleteSessionTools } from "../shared/session-tools-store";
+import { lspManager } from "../tools";

-import type { CreatedHooks } from "../create-hooks"
-import type { Managers } from "../create-managers"
-import { normalizeSessionStatusToIdle } from "./session-status-normalizer"
-import { pruneRecentSyntheticIdles } from "./recent-synthetic-idles"
+import type { CreatedHooks } from "../create-hooks";
+import type { Managers } from "../create-managers";
+import { pruneRecentSyntheticIdles } from "./recent-synthetic-idles";
+import { normalizeSessionStatusToIdle } from "./session-status-normalizer";

 type FirstMessageVariantGate = {
-  markSessionCreated: (sessionInfo: { id?: string; title?: string; parentID?: string } | undefined) => void
-  clear: (sessionID: string) => void
-}
+  markSessionCreated: (sessionInfo: { id?: string; title?: string; parentID?: string } | undefined) => void;
+  clear: (sessionID: string) => void;
+};

 function isRecord(value: unknown): value is Record<string, unknown> {
-  return typeof value === "object" && value !== null
+  return typeof value === "object" && value !== null;
 }

 function normalizeFallbackModelID(modelID: string): string {
  return modelID
    .replace(/-thinking$/i, "")
    .replace(/-max$/i, "")
-    .replace(/-high$/i, "")
+    .replace(/-high$/i, "");
 }

 function extractErrorName(error: unknown): string | undefined {
-  if (isRecord(error) && typeof error.name === "string") return error.name
-  if (error instanceof Error) return error.name
-  return undefined
+  if (isRecord(error) && typeof error.name === "string") return error.name;
+  if (error instanceof Error) return error.name;
+  return undefined;
 }

 function extractErrorMessage(error: unknown): string {
-  if (!error) return ""
-  if (typeof error === "string") return error
-  if (error instanceof Error) return error.message
+  if (!error) return "";
+  if (typeof error === "string") return error;
+  if (error instanceof Error) return error.message;

  if (isRecord(error)) {
    const candidates: unknown[] = [
@@ -56,116 +61,112 @@ function extractErrorMessage(error: unknown): string {
      error.error,
      isRecord(error.data) ? error.data.error : undefined,
      error.cause,
-    ]
+    ];

    for (const candidate of candidates) {
      if (isRecord(candidate) && typeof candidate.message === "string" && candidate.message.length > 0) {
-        return candidate.message
+        return candidate.message;
      }
    }
  }

  try {
-    return JSON.stringify(error)
+    return JSON.stringify(error);
  } catch {
-    return String(error)
+    return String(error);
  }
 }

-function extractProviderModelFromErrorMessage(
-  message: string,
-): { providerID?: string; modelID?: string } {
-  const lower = message.toLowerCase()
+function extractProviderModelFromErrorMessage(message: string): { providerID?: string; modelID?: string } {
+  const lower = message.toLowerCase();

-  const providerModel = lower.match(/model\s+not\s+found:\s*([a-z0-9_-]+)\s*\/\s*([a-z0-9._-]+)/i)
+  const providerModel = lower.match(/model\s+not\s+found:\s*([a-z0-9_-]+)\s*\/\s*([a-z0-9._-]+)/i);
  if (providerModel) {
    return {
      providerID: providerModel[1],
      modelID: providerModel[2],
-    }
+    };
  }

-  const modelOnly = lower.match(/unknown\s+provider\s+for\s+model\s+([a-z0-9._-]+)/i)
+  const modelOnly = lower.match(/unknown\s+provider\s+for\s+model\s+([a-z0-9._-]+)/i);
  if (modelOnly) {
    return {
      modelID: modelOnly[1],
-    }
+    };
  }

-  return {}
+  return {};
 }
-type EventInput = Parameters<
-  NonNullable<NonNullable<CreatedHooks["writeExistingFileGuard"]>["event"]>
->[0]
+type EventInput = Parameters<NonNullable<NonNullable<CreatedHooks["writeExistingFileGuard"]>["event"]>>[0];
 export function createEventHandler(args: {
-  ctx: PluginContext
-  pluginConfig: OhMyOpenCodeConfig
-  firstMessageVariantGate: FirstMessageVariantGate
-  managers: Managers
-  hooks: CreatedHooks
+  ctx: PluginContext;
+  pluginConfig: OhMyOpenCodeConfig;
+  firstMessageVariantGate: FirstMessageVariantGate;
+  managers: Managers;
+  hooks: CreatedHooks;
 }): (input: EventInput) => Promise<void> {
-  const { ctx, firstMessageVariantGate, managers, hooks } = args
+  const { ctx, firstMessageVariantGate, managers, hooks } = args;
  const pluginContext = ctx as {
-    directory: string
+    directory: string;
    client: {
      session: {
-        abort: (input: { path: { id: string } }) => Promise<unknown>
+        abort: (input: { path: { id: string } }) => Promise<unknown>;
        prompt: (input: {
-          path: { id: string }
-          body: { parts: Array<{ type: "text"; text: string }> }
-          query: { directory: string }
-        }) => Promise<unknown>
-      }
-    }
-  }
+          path: { id: string };
+          body: { parts: Array<{ type: "text"; text: string }> };
+          query: { directory: string };
+        }) => Promise<unknown>;
+      };
+    };
+  };
  const isRuntimeFallbackEnabled =
    hooks.runtimeFallback !== null &&
    hooks.runtimeFallback !== undefined &&
    (typeof args.pluginConfig.runtime_fallback === "boolean"
      ? args.pluginConfig.runtime_fallback
-      : (args.pluginConfig.runtime_fallback?.enabled ?? false))
+      : (args.pluginConfig.runtime_fallback?.enabled ?? false));

  // Avoid triggering multiple abort+continue cycles for the same failing assistant message.
-  const lastHandledModelErrorMessageID = new Map<string, string>()
-  const lastHandledRetryStatusKey = new Map<string, string>()
-  const lastKnownModelBySession = new Map<string, { providerID: string; modelID: string }>()
+  const lastHandledModelErrorMessageID = new Map<string, string>();
+  const lastHandledRetryStatusKey = new Map<string, string>();
+  const lastKnownModelBySession = new Map<string, { providerID: string; modelID: string }>();

  const dispatchToHooks = async (input: EventInput): Promise<void> => {
-    await Promise.resolve(hooks.autoUpdateChecker?.event?.(input))
-    await Promise.resolve(hooks.claudeCodeHooks?.event?.(input))
-    await Promise.resolve(hooks.backgroundNotificationHook?.event?.(input))
-    await Promise.resolve(hooks.sessionNotification?.(input))
-    await Promise.resolve(hooks.todoContinuationEnforcer?.handler?.(input))
-    await Promise.resolve(hooks.unstableAgentBabysitter?.event?.(input))
-    await Promise.resolve(hooks.contextWindowMonitor?.event?.(input))
-    await Promise.resolve(hooks.directoryAgentsInjector?.event?.(input))
-    await Promise.resolve(hooks.directoryReadmeInjector?.event?.(input))
-    await Promise.resolve(hooks.rulesInjector?.event?.(input))
-    await Promise.resolve(hooks.thinkMode?.event?.(input))
-    await Promise.resolve(hooks.anthropicContextWindowLimitRecovery?.event?.(input))
-    await Promise.resolve(hooks.runtimeFallback?.event?.(input))
-    await Promise.resolve(hooks.agentUsageReminder?.event?.(input))
-    await Promise.resolve(hooks.categorySkillReminder?.event?.(input))
-    await Promise.resolve(hooks.interactiveBashSession?.event?.(input as EventInput))
-    await Promise.resolve(hooks.ralphLoop?.event?.(input))
-    await Promise.resolve(hooks.stopContinuationGuard?.event?.(input))
-    await Promise.resolve(hooks.compactionTodoPreserver?.event?.(input))
-    await Promise.resolve(hooks.writeExistingFileGuard?.event?.(input))
-    await Promise.resolve(hooks.atlasHook?.handler?.(input))
-  }
+    await Promise.resolve(hooks.autoUpdateChecker?.event?.(input));
+    await Promise.resolve(hooks.claudeCodeHooks?.event?.(input));
+    await Promise.resolve(hooks.backgroundNotificationHook?.event?.(input));
+    await Promise.resolve(hooks.sessionNotification?.(input));
+    await Promise.resolve(hooks.todoContinuationEnforcer?.handler?.(input));
+    await Promise.resolve(hooks.unstableAgentBabysitter?.event?.(input));
+    await Promise.resolve(hooks.contextWindowMonitor?.event?.(input));
+    await Promise.resolve(hooks.directoryAgentsInjector?.event?.(input));
+    await Promise.resolve(hooks.directoryReadmeInjector?.event?.(input));
+    await Promise.resolve(hooks.rulesInjector?.event?.(input));
+    await Promise.resolve(hooks.thinkMode?.event?.(input));
+    await Promise.resolve(hooks.anthropicContextWindowLimitRecovery?.event?.(input));
+    await Promise.resolve(hooks.runtimeFallback?.event?.(input));
+    await Promise.resolve(hooks.agentUsageReminder?.event?.(input));
+    await Promise.resolve(hooks.categorySkillReminder?.event?.(input));
+    await Promise.resolve(hooks.interactiveBashSession?.event?.(input as EventInput));
+    await Promise.resolve(hooks.ralphLoop?.event?.(input));
+    await Promise.resolve(hooks.stopContinuationGuard?.event?.(input));
+    await Promise.resolve(hooks.compactionTodoPreserver?.event?.(input));
+    await Promise.resolve(hooks.writeExistingFileGuard?.event?.(input));
+    await Promise.resolve(hooks.atlasHook?.handler?.(input));
+  };

-  const recentSyntheticIdles = new Map<string, number>()
-  const recentRealIdles = new Map<string, number>()
-  const DEDUP_WINDOW_MS = 500
+  const recentSyntheticIdles = new Map<string, number>();
+  const recentRealIdles = new Map<string, number>();
+  const DEDUP_WINDOW_MS = 500;

  const shouldAutoRetrySession = (sessionID: string): boolean => {
-    if (syncSubagentSessions.has(sessionID)) return true
-    const mainSessionID = getMainSessionID()
-    if (mainSessionID) return sessionID === mainSessionID
+    if (syncSubagentSessions.has(sessionID)) return true;
+    const mainSessionID = getMainSessionID();
+    if (mainSessionID) return sessionID === mainSessionID;
    // Headless runs (or resumed sessions) may not emit session.created, so mainSessionID can be unset.
    // In that case, treat any non-subagent session as the "main" interactive session.
-    return !subagentSessions.has(sessionID)
-  }
+    return !subagentSessions.has(sessionID);
+  };

  return async (input): Promise<void> => {
    pruneRecentSyntheticIdles({
@@ -173,97 +174,98 @@ export function createEventHandler(args: {
      recentRealIdles,
      now: Date.now(),
      dedupWindowMs: DEDUP_WINDOW_MS,
-    })
+    });

    if (input.event.type === "session.idle") {
-      const sessionID = (input.event.properties as Record<string, unknown> | undefined)?.sessionID as string | undefined
+      const sessionID = (input.event.properties as Record<string, unknown> | undefined)?.sessionID as
+        | string
+        | undefined;
      if (sessionID) {
-        const emittedAt = recentSyntheticIdles.get(sessionID)
+        const emittedAt = recentSyntheticIdles.get(sessionID);
        if (emittedAt && Date.now() - emittedAt < DEDUP_WINDOW_MS) {
-          recentSyntheticIdles.delete(sessionID)
-          return
+          recentSyntheticIdles.delete(sessionID);
+          return;
        }
-        recentRealIdles.set(sessionID, Date.now())
+        recentRealIdles.set(sessionID, Date.now());
      }
    }

-    await dispatchToHooks(input)
+    await dispatchToHooks(input);

-    const syntheticIdle = normalizeSessionStatusToIdle(input)
+    const syntheticIdle = normalizeSessionStatusToIdle(input);
    if (syntheticIdle) {
-      const sessionID = (syntheticIdle.event.properties as Record<string, unknown>)?.sessionID as string
-      const emittedAt = recentRealIdles.get(sessionID)
+      const sessionID = (syntheticIdle.event.properties as Record<string, unknown>)?.sessionID as string;
+      const emittedAt = recentRealIdles.get(sessionID);
      if (emittedAt && Date.now() - emittedAt < DEDUP_WINDOW_MS) {
-        recentRealIdles.delete(sessionID)
-        return
+        recentRealIdles.delete(sessionID);
+        return;
      }
-      recentSyntheticIdles.set(sessionID, Date.now())
-      await dispatchToHooks(syntheticIdle as EventInput)
+      recentSyntheticIdles.set(sessionID, Date.now());
+      await dispatchToHooks(syntheticIdle as EventInput);
    }

-    const { event } = input
-    const props = event.properties as Record<string, unknown> | undefined
+    const { event } = input;
+    const props = event.properties as Record<string, unknown> | undefined;

    if (event.type === "session.created") {
-      const sessionInfo = props?.info as
-        | { id?: string; title?: string; parentID?: string }
-        | undefined
+      const sessionInfo = props?.info as { id?: string; title?: string; parentID?: string } | undefined;

      if (!sessionInfo?.parentID) {
-        setMainSession(sessionInfo?.id)
+        setMainSession(sessionInfo?.id);
      }

-      firstMessageVariantGate.markSessionCreated(sessionInfo)
+      firstMessageVariantGate.markSessionCreated(sessionInfo);

      await managers.tmuxSessionManager.onSessionCreated(
        event as {
-          type: string
+          type: string;
          properties?: {
-            info?: { id?: string; parentID?: string; title?: string }
-          }
+            info?: { id?: string; parentID?: string; title?: string };
+          };
        },
-      )
+      );
    }

    if (event.type === "session.deleted") {
-      const sessionInfo = props?.info as { id?: string } | undefined
+      const sessionInfo = props?.info as { id?: string } | undefined;
      if (sessionInfo?.id === getMainSessionID()) {
-        setMainSession(undefined)
+        setMainSession(undefined);
      }

      if (sessionInfo?.id) {
-        clearSessionAgent(sessionInfo.id)
-        lastHandledModelErrorMessageID.delete(sessionInfo.id)
-        lastHandledRetryStatusKey.delete(sessionInfo.id)
-        lastKnownModelBySession.delete(sessionInfo.id)
-        clearPendingModelFallback(sessionInfo.id)
-        clearSessionFallbackChain(sessionInfo.id)
-        resetMessageCursor(sessionInfo.id)
-        firstMessageVariantGate.clear(sessionInfo.id)
-        clearSessionModel(sessionInfo.id)
-        syncSubagentSessions.delete(sessionInfo.id)
-        await managers.skillMcpManager.disconnectSession(sessionInfo.id)
-        await lspManager.cleanupTempDirectoryClients()
+        clearSessionAgent(sessionInfo.id);
+        lastHandledModelErrorMessageID.delete(sessionInfo.id);
+        lastHandledRetryStatusKey.delete(sessionInfo.id);
+        lastKnownModelBySession.delete(sessionInfo.id);
+        clearPendingModelFallback(sessionInfo.id);
+        clearSessionFallbackChain(sessionInfo.id);
+        resetMessageCursor(sessionInfo.id);
+        firstMessageVariantGate.clear(sessionInfo.id);
+        clearSessionModel(sessionInfo.id);
+        syncSubagentSessions.delete(sessionInfo.id);
+        deleteSessionTools(sessionInfo.id);
+        await managers.skillMcpManager.disconnectSession(sessionInfo.id);
+        await lspManager.cleanupTempDirectoryClients();
        await managers.tmuxSessionManager.onSessionDeleted({
          sessionID: sessionInfo.id,
-        })
+        });
      }
    }

    if (event.type === "message.updated") {
-      const info = props?.info as Record<string, unknown> | undefined
-      const sessionID = info?.sessionID as string | undefined
-      const agent = info?.agent as string | undefined
-      const role = info?.role as string | undefined
+      const info = props?.info as Record<string, unknown> | undefined;
+      const sessionID = info?.sessionID as string | undefined;
+      const agent = info?.agent as string | undefined;
+      const role = info?.role as string | undefined;
      if (sessionID && role === "user") {
        if (agent) {
-          updateSessionAgent(sessionID, agent)
+          updateSessionAgent(sessionID, agent);
        }
-        const providerID = info?.providerID as string | undefined
-        const modelID = info?.modelID as string | undefined
+        const providerID = info?.providerID as string | undefined;
+        const modelID = info?.modelID as string | undefined;
        if (providerID && modelID) {
-          lastKnownModelBySession.set(sessionID, { providerID, modelID })
-          setSessionModel(sessionID, { providerID, modelID })
+          lastKnownModelBySession.set(sessionID, { providerID, modelID });
+          setSessionModel(sessionID, { providerID, modelID });
        }
      }

@@ -271,132 +273,128 @@ export function createEventHandler(args: {
      // session.error events are not guaranteed for all providers, so we also observe message.updated.
      if (sessionID && role === "assistant" && !isRuntimeFallbackEnabled) {
        try {
-          const assistantMessageID = info?.id as string | undefined
-          const assistantError = info?.error
+          const assistantMessageID = info?.id as string | undefined;
+          const assistantError = info?.error;
          if (assistantMessageID && assistantError) {
-            const lastHandled = lastHandledModelErrorMessageID.get(sessionID)
+            const lastHandled = lastHandledModelErrorMessageID.get(sessionID);
            if (lastHandled === assistantMessageID) {
-              return
+              return;
            }

-            const errorName = extractErrorName(assistantError)
-            const errorMessage = extractErrorMessage(assistantError)
-            const errorInfo = { name: errorName, message: errorMessage }
+            const errorName = extractErrorName(assistantError);
+            const errorMessage = extractErrorMessage(assistantError);
+            const errorInfo = { name: errorName, message: errorMessage };

            if (shouldRetryError(errorInfo)) {
              // Prefer the agent/model/provider from the assistant message payload.
-              let agentName = agent ?? getSessionAgent(sessionID)
+              let agentName = agent ?? getSessionAgent(sessionID);
              if (!agentName && sessionID === getMainSessionID()) {
                if (errorMessage.includes("claude-opus") || errorMessage.includes("opus")) {
-                  agentName = "sisyphus"
+                  agentName = "sisyphus";
                } else if (errorMessage.includes("gpt-5")) {
-                  agentName = "hephaestus"
+                  agentName = "hephaestus";
                } else {
-                  agentName = "sisyphus"
+                  agentName = "sisyphus";
                }
              }

              if (agentName) {
-                const currentProvider = (info?.providerID as string | undefined) ?? "opencode"
-                const rawModel = (info?.modelID as string | undefined) ?? "claude-opus-4-6"
-                const currentModel = normalizeFallbackModelID(rawModel)
+                const currentProvider = (info?.providerID as string | undefined) ?? "opencode";
+                const rawModel = (info?.modelID as string | undefined) ?? "claude-opus-4-6";
+                const currentModel = normalizeFallbackModelID(rawModel);

-                const setFallback = setPendingModelFallback(
-                  sessionID,
-                  agentName,
-                  currentProvider,
-                  currentModel,
-                )
+                const setFallback = setPendingModelFallback(sessionID, agentName, currentProvider, currentModel);

-                if (setFallback && shouldAutoRetrySession(sessionID) && !hooks.stopContinuationGuard?.isStopped(sessionID)) {
-                  lastHandledModelErrorMessageID.set(sessionID, assistantMessageID)
+                if (
+                  setFallback &&
+                  shouldAutoRetrySession(sessionID) &&
+                  !hooks.stopContinuationGuard?.isStopped(sessionID)
+                ) {
+                  lastHandledModelErrorMessageID.set(sessionID, assistantMessageID);

-                  await pluginContext.client.session.abort({ path: { id: sessionID } }).catch(() => {})
+                  await pluginContext.client.session.abort({ path: { id: sessionID } }).catch(() => {});
                  await pluginContext.client.session
                    .prompt({
                      path: { id: sessionID },
                      body: { parts: [{ type: "text", text: "continue" }] },
                      query: { directory: pluginContext.directory },
                    })
-                    .catch(() => {})
+                    .catch(() => {});
                }
              }
            }
          }
        } catch (err) {
-          log("[event] model-fallback error in message.updated:", { sessionID, error: err })
+          log("[event] model-fallback error in message.updated:", { sessionID, error: err });
        }
      }
    }

    if (event.type === "session.status") {
-      const sessionID = props?.sessionID as string | undefined
-      const status = props?.status as
-        | { type?: string; attempt?: number; message?: string; next?: number }
-        | undefined
+      const sessionID = props?.sessionID as string | undefined;
+      const status = props?.status as { type?: string; attempt?: number; message?: string; next?: number } | undefined;

      if (sessionID && status?.type === "retry") {
        try {
-          const retryMessage = typeof status.message === "string" ? status.message : ""
-          const retryKey = `${status.attempt ?? "?"}:${status.next ?? "?"}:${retryMessage}`
+          const retryMessage = typeof status.message === "string" ? status.message : "";
+          const retryKey = `${status.attempt ?? "?"}:${status.next ?? "?"}:${retryMessage}`;
          if (lastHandledRetryStatusKey.get(sessionID) === retryKey) {
-            return
+            return;
          }
-          lastHandledRetryStatusKey.set(sessionID, retryKey)
+          lastHandledRetryStatusKey.set(sessionID, retryKey);

-          const errorInfo = { name: undefined as string | undefined, message: retryMessage }
+          const errorInfo = { name: undefined as string | undefined, message: retryMessage };
          if (shouldRetryError(errorInfo)) {
-            let agentName = getSessionAgent(sessionID)
+            let agentName = getSessionAgent(sessionID);
            if (!agentName && sessionID === getMainSessionID()) {
              if (retryMessage.includes("claude-opus") || retryMessage.includes("opus")) {
-                agentName = "sisyphus"
+                agentName = "sisyphus";
              } else if (retryMessage.includes("gpt-5")) {
-                agentName = "hephaestus"
+                agentName = "hephaestus";
              } else {
-                agentName = "sisyphus"
+                agentName = "sisyphus";
              }
            }

            if (agentName) {
-              const parsed = extractProviderModelFromErrorMessage(retryMessage)
-              const lastKnown = lastKnownModelBySession.get(sessionID)
-              const currentProvider = parsed.providerID ?? lastKnown?.providerID ?? "opencode"
-              let currentModel = parsed.modelID ?? lastKnown?.modelID ?? "claude-opus-4-6"
-              currentModel = normalizeFallbackModelID(currentModel)
+              const parsed = extractProviderModelFromErrorMessage(retryMessage);
+              const lastKnown = lastKnownModelBySession.get(sessionID);
+              const currentProvider = parsed.providerID ?? lastKnown?.providerID ?? "opencode";
+              let currentModel = parsed.modelID ?? lastKnown?.modelID ?? "claude-opus-4-6";
+              currentModel = normalizeFallbackModelID(currentModel);

-              const setFallback = setPendingModelFallback(
-                sessionID,
-                agentName,
-                currentProvider,
-                currentModel,
-              )
+              const setFallback = setPendingModelFallback(sessionID, agentName, currentProvider, currentModel);

-              if (setFallback && shouldAutoRetrySession(sessionID) && !hooks.stopContinuationGuard?.isStopped(sessionID)) {
-                await pluginContext.client.session.abort({ path: { id: sessionID } }).catch(() => {})
+              if (
+                setFallback &&
+                shouldAutoRetrySession(sessionID) &&
+                !hooks.stopContinuationGuard?.isStopped(sessionID)
+              ) {
+                await pluginContext.client.session.abort({ path: { id: sessionID } }).catch(() => {});
                await pluginContext.client.session
                  .prompt({
                    path: { id: sessionID },
                    body: { parts: [{ type: "text", text: "continue" }] },
                    query: { directory: pluginContext.directory },
                  })
-                  .catch(() => {})
+                  .catch(() => {});
              }
            }
          }
        } catch (err) {
-          log("[event] model-fallback error in session.status:", { sessionID, error: err })
+          log("[event] model-fallback error in session.status:", { sessionID, error: err });
        }
      }
    }

    if (event.type === "session.error") {
      try {
-        const sessionID = props?.sessionID as string | undefined
-        const error = props?.error
+        const sessionID = props?.sessionID as string | undefined;
+        const error = props?.error;

-        const errorName = extractErrorName(error)
-        const errorMessage = extractErrorMessage(error)
-        const errorInfo = { name: errorName, message: errorMessage }
+        const errorName = extractErrorName(error);
+        const errorMessage = extractErrorMessage(error);
+        const errorInfo = { name: errorName, message: errorMessage };

        // First, try session recovery for internal errors (thinking blocks, tool results, etc.)
        if (hooks.sessionRecovery?.isRecoverableError(error)) {
@@ -405,8 +403,8 @@ export function createEventHandler(args: {
            role: "assistant" as const,
            sessionID,
            error,
-          }
-          const recovered = await hooks.sessionRecovery.handleSessionRecovery(messageInfo)
+          };
+          const recovered = await hooks.sessionRecovery.handleSessionRecovery(messageInfo);

          if (
            recovered &&
@@ -420,53 +418,52 @@ export function createEventHandler(args: {
                body: { parts: [{ type: "text", text: "continue" }] },
                query: { directory: pluginContext.directory },
              })
-              .catch(() => {})
+              .catch(() => {});
          }
-        } 
+        }
        // Second, try model fallback for model errors (rate limit, quota, provider issues, etc.)
        else if (sessionID && shouldRetryError(errorInfo) && !isRuntimeFallbackEnabled) {
-          let agentName = getSessionAgent(sessionID)
-          
+          let agentName = getSessionAgent(sessionID);
+
          if (!agentName && sessionID === getMainSessionID()) {
            if (errorMessage.includes("claude-opus") || errorMessage.includes("opus")) {
-              agentName = "sisyphus"
+              agentName = "sisyphus";
            } else if (errorMessage.includes("gpt-5")) {
-              agentName = "hephaestus"
+              agentName = "hephaestus";
            } else {
-              agentName = "sisyphus"
+              agentName = "sisyphus";
            }
          }
-          
-          if (agentName) {
-            const parsed = extractProviderModelFromErrorMessage(errorMessage)
-            const currentProvider = props?.providerID as string || parsed.providerID || "opencode"
-            let currentModel = props?.modelID as string || parsed.modelID || "claude-opus-4-6"
-            currentModel = normalizeFallbackModelID(currentModel)

-            const setFallback = setPendingModelFallback(
-              sessionID,
-              agentName,
-              currentProvider,
-              currentModel,
-            )
-            
-            if (setFallback && shouldAutoRetrySession(sessionID) && !hooks.stopContinuationGuard?.isStopped(sessionID)) {
-                await pluginContext.client.session.abort({ path: { id: sessionID } }).catch(() => {})
-                
-                await pluginContext.client.session
-                  .prompt({
-                    path: { id: sessionID },
-                    body: { parts: [{ type: "text", text: "continue" }] },
-                    query: { directory: pluginContext.directory },
-                  })
-                  .catch(() => {})
+          if (agentName) {
+            const parsed = extractProviderModelFromErrorMessage(errorMessage);
+            const currentProvider = (props?.providerID as string) || parsed.providerID || "opencode";
+            let currentModel = (props?.modelID as string) || parsed.modelID || "claude-opus-4-6";
+            currentModel = normalizeFallbackModelID(currentModel);
+
+            const setFallback = setPendingModelFallback(sessionID, agentName, currentProvider, currentModel);
+
+            if (
+              setFallback &&
+              shouldAutoRetrySession(sessionID) &&
+              !hooks.stopContinuationGuard?.isStopped(sessionID)
+            ) {
+              await pluginContext.client.session.abort({ path: { id: sessionID } }).catch(() => {});
+
+              await pluginContext.client.session
+                .prompt({
+                  path: { id: sessionID },
+                  body: { parts: [{ type: "text", text: "continue" }] },
+                  query: { directory: pluginContext.directory },
+                })
+                .catch(() => {});
            }
          }
        }
      } catch (err) {
-        const sessionID = props?.sessionID as string | undefined
-        log("[event] model-fallback error in session.error:", { sessionID, error: err })
+        const sessionID = props?.sessionID as string | undefined;
+        log("[event] model-fallback error in session.error:", { sessionID, error: err });
      }
    }
-  }
+  };
 }
--- a/src/shared/command-executor/execute-hook-command.ts
+++ b/src/shared/command-executor/execute-hook-command.ts
@@ -1,78 +1,129 @@
-import { spawn } from "node:child_process"
-import { getHomeDirectory } from "./home-directory"
-import { findBashPath, findZshPath } from "./shell-path"
+import { spawn } from "node:child_process";
+import { getHomeDirectory } from "./home-directory";
+import { findBashPath, findZshPath } from "./shell-path";

 export interface CommandResult {
-	exitCode: number
-	stdout?: string
-	stderr?: string
+  exitCode: number;
+  stdout?: string;
+  stderr?: string;
 }

+const DEFAULT_HOOK_TIMEOUT_MS = 30_000;
+const SIGKILL_GRACE_MS = 5_000;
+
 export interface ExecuteHookOptions {
-	forceZsh?: boolean
-	zshPath?: string
+  forceZsh?: boolean;
+  zshPath?: string;
+  /** Timeout in milliseconds. Process is killed after this. Default: 30000 */
+  timeoutMs?: number;
 }

 export async function executeHookCommand(
-	command: string,
-	stdin: string,
-	cwd: string,
-	options?: ExecuteHookOptions,
+  command: string,
+  stdin: string,
+  cwd: string,
+  options?: ExecuteHookOptions,
 ): Promise<CommandResult> {
-	const home = getHomeDirectory()
+  const home = getHomeDirectory();
+  const timeoutMs = options?.timeoutMs ?? DEFAULT_HOOK_TIMEOUT_MS;

-	const expandedCommand = command
-		.replace(/^~(?=\/|$)/g, home)
-		.replace(/\s~(?=\/)/g, ` ${home}`)
-		.replace(/\$CLAUDE_PROJECT_DIR/g, cwd)
-		.replace(/\$\{CLAUDE_PROJECT_DIR\}/g, cwd)
+  const expandedCommand = command
+    .replace(/^~(?=\/|$)/g, home)
+    .replace(/\s~(?=\/)/g, ` ${home}`)
+    .replace(/\$CLAUDE_PROJECT_DIR/g, cwd)
+    .replace(/\$\{CLAUDE_PROJECT_DIR\}/g, cwd);

-	let finalCommand = expandedCommand
+  let finalCommand = expandedCommand;

-	if (options?.forceZsh) {
-		const zshPath = findZshPath(options.zshPath)
-		const escapedCommand = expandedCommand.replace(/'/g, "'\\''")
-		if (zshPath) {
-			finalCommand = `${zshPath} -lc '${escapedCommand}'`
-		} else {
-			const bashPath = findBashPath()
-			if (bashPath) {
-				finalCommand = `${bashPath} -lc '${escapedCommand}'`
-			}
-		}
-	}
+  if (options?.forceZsh) {
+    const zshPath = findZshPath(options.zshPath);
+    const escapedCommand = expandedCommand.replace(/'/g, "'\\''");
+    if (zshPath) {
+      finalCommand = `${zshPath} -lc '${escapedCommand}'`;
+    } else {
+      const bashPath = findBashPath();
+      if (bashPath) {
+        finalCommand = `${bashPath} -lc '${escapedCommand}'`;
+      }
+    }
+  }

-	return new Promise((resolve) => {
-		const proc = spawn(finalCommand, {
-			cwd,
-			shell: true,
-			env: { ...process.env, HOME: home, CLAUDE_PROJECT_DIR: cwd },
-		})
+  return new Promise(resolve => {
+    let settled = false;
+    let killTimer: ReturnType<typeof setTimeout> | null = null;

-		let stdout = ""
-		let stderr = ""
+    const isWin32 = process.platform === "win32";
+    const proc = spawn(finalCommand, {
+      cwd,
+      shell: true,
+      detached: !isWin32,
+      env: { ...process.env, HOME: home, CLAUDE_PROJECT_DIR: cwd },
+    });

-		proc.stdout?.on("data", (data) => {
-			stdout += data.toString()
-		})
+    let stdout = "";
+    let stderr = "";

-		proc.stderr?.on("data", (data) => {
-			stderr += data.toString()
-		})
+    proc.stdout?.on("data", (data: Buffer) => {
+      stdout += data.toString();
+    });

-		proc.stdin?.write(stdin)
-		proc.stdin?.end()
+    proc.stderr?.on("data", (data: Buffer) => {
+      stderr += data.toString();
+    });

-		proc.on("close", (code) => {
-			resolve({
-				exitCode: code ?? 0,
-				stdout: stdout.trim(),
-				stderr: stderr.trim(),
-			})
-		})
+    proc.stdin?.on("error", () => {});
+    proc.stdin?.write(stdin);
+    proc.stdin?.end();

-		proc.on("error", (err) => {
-			resolve({ exitCode: 1, stderr: err.message })
-		})
-	})
+    const settle = (result: CommandResult) => {
+      if (settled) return;
+      settled = true;
+      if (killTimer) clearTimeout(killTimer);
+      if (timeoutTimer) clearTimeout(timeoutTimer);
+      resolve(result);
+    };
+
+    proc.on("close", code => {
+      settle({
+        exitCode: code ?? 1,
+        stdout: stdout.trim(),
+        stderr: stderr.trim(),
+      });
+    });
+
+    proc.on("error", err => {
+      settle({ exitCode: 1, stderr: err.message });
+    });
+
+    const killProcessGroup = (signal: NodeJS.Signals) => {
+      try {
+        if (!isWin32 && proc.pid) {
+          try {
+            process.kill(-proc.pid, signal);
+          } catch {
+            proc.kill(signal);
+          }
+        } else {
+          proc.kill(signal);
+        }
+      } catch {}
+    };
+
+    const timeoutTimer = setTimeout(() => {
+      if (settled) return;
+      // Kill entire process group to avoid orphaned children
+      killProcessGroup("SIGTERM");
+      killTimer = setTimeout(() => {
+        if (settled) return;
+        killProcessGroup("SIGKILL");
+      }, SIGKILL_GRACE_MS);
+      // Append timeout notice to stderr
+      stderr += `\nHook command timed out after ${timeoutMs}ms`;
+    }, timeoutMs);
+
+    // Don't let the timeout timer keep the process alive
+    if (timeoutTimer && typeof timeoutTimer === "object" && "unref" in timeoutTimer) {
+      timeoutTimer.unref();
+    }
+  });
 }
--- a/src/shared/session-tools-store.ts
+++ b/src/shared/session-tools-store.ts
@@ -1,14 +1,18 @@
-const store = new Map<string, Record<string, boolean>>()
+const store = new Map<string, Record<string, boolean>>();

 export function setSessionTools(sessionID: string, tools: Record<string, boolean>): void {
-  store.set(sessionID, { ...tools })
+  store.set(sessionID, { ...tools });
 }

 export function getSessionTools(sessionID: string): Record<string, boolean> | undefined {
-  const tools = store.get(sessionID)
-  return tools ? { ...tools } : undefined
+  const tools = store.get(sessionID);
+  return tools ? { ...tools } : undefined;
+}
+
+export function deleteSessionTools(sessionID: string): void {
+  store.delete(sessionID);
 }

 export function clearSessionTools(): void {
-  store.clear()
+  store.clear();
 }
--- a/src/tools/hashline-edit/autocorrect-replacement-lines.ts
+++ b/src/tools/hashline-edit/autocorrect-replacement-lines.ts
@@ -0,0 +1,175 @@
+function normalizeTokens(text: string): string {
+  return text.replace(/\s+/g, "")
+}
+
+function stripAllWhitespace(text: string): string {
+  return normalizeTokens(text)
+}
+
+export function stripTrailingContinuationTokens(text: string): string {
+  return text.replace(/(?:&&|\|\||\?\?|\?|:|=|,|\+|-|\*|\/|\.|\()\s*$/u, "")
+}
+
+export function stripMergeOperatorChars(text: string): string {
+  return text.replace(/[|&?]/g, "")
+}
+
+function leadingWhitespace(text: string): string {
+  const match = text.match(/^\s*/)
+  return match ? match[0] : ""
+}
+
+export function restoreOldWrappedLines(originalLines: string[], replacementLines: string[]): string[] {
+  if (originalLines.length === 0 || replacementLines.length < 2) return replacementLines
+
+  const canonicalToOriginal = new Map<string, { line: string; count: number }>()
+  for (const line of originalLines) {
+    const canonical = stripAllWhitespace(line)
+    const existing = canonicalToOriginal.get(canonical)
+    if (existing) {
+      existing.count += 1
+    } else {
+      canonicalToOriginal.set(canonical, { line, count: 1 })
+    }
+  }
+
+  const candidates: { start: number; len: number; replacement: string; canonical: string }[] = []
+  for (let start = 0; start < replacementLines.length; start += 1) {
+    for (let len = 2; len <= 10 && start + len <= replacementLines.length; len += 1) {
+      const canonicalSpan = stripAllWhitespace(replacementLines.slice(start, start + len).join(""))
+      const original = canonicalToOriginal.get(canonicalSpan)
+      if (original && original.count === 1 && canonicalSpan.length >= 6) {
+        candidates.push({ start, len, replacement: original.line, canonical: canonicalSpan })
+      }
+    }
+  }
+  if (candidates.length === 0) return replacementLines
+
+  const canonicalCounts = new Map<string, number>()
+  for (const candidate of candidates) {
+    canonicalCounts.set(candidate.canonical, (canonicalCounts.get(candidate.canonical) ?? 0) + 1)
+  }
+
+  const uniqueCandidates = candidates.filter((candidate) => (canonicalCounts.get(candidate.canonical) ?? 0) === 1)
+  if (uniqueCandidates.length === 0) return replacementLines
+
+  uniqueCandidates.sort((a, b) => b.start - a.start)
+  const correctedLines = [...replacementLines]
+  for (const candidate of uniqueCandidates) {
+    correctedLines.splice(candidate.start, candidate.len, candidate.replacement)
+  }
+  return correctedLines
+}
+
+export function maybeExpandSingleLineMerge(
+  originalLines: string[],
+  replacementLines: string[]
+): string[] {
+  if (replacementLines.length !== 1 || originalLines.length <= 1) {
+    return replacementLines
+  }
+
+  const merged = replacementLines[0]
+  const parts = originalLines.map((line) => line.trim()).filter((line) => line.length > 0)
+  if (parts.length !== originalLines.length) return replacementLines
+
+  const indices: number[] = []
+  let offset = 0
+  let orderedMatch = true
+  for (const part of parts) {
+    let idx = merged.indexOf(part, offset)
+    let matchedLen = part.length
+    if (idx === -1) {
+      const stripped = stripTrailingContinuationTokens(part)
+      if (stripped !== part) {
+        idx = merged.indexOf(stripped, offset)
+        if (idx !== -1) matchedLen = stripped.length
+      }
+    }
+    if (idx === -1) {
+      const segment = merged.slice(offset)
+      const segmentStripped = stripMergeOperatorChars(segment)
+      const partStripped = stripMergeOperatorChars(part)
+      const fuzzyIdx = segmentStripped.indexOf(partStripped)
+      if (fuzzyIdx !== -1) {
+        let strippedPos = 0
+        let originalPos = 0
+        while (strippedPos < fuzzyIdx && originalPos < segment.length) {
+          if (!/[|&?]/.test(segment[originalPos])) strippedPos += 1
+          originalPos += 1
+        }
+        idx = offset + originalPos
+        matchedLen = part.length
+      }
+    }
+    if (idx === -1) {
+      orderedMatch = false
+      break
+    }
+    indices.push(idx)
+    offset = idx + matchedLen
+  }
+
+  const expanded: string[] = []
+  if (orderedMatch) {
+    for (let i = 0; i < indices.length; i += 1) {
+      const start = indices[i]
+      const end = i + 1 < indices.length ? indices[i + 1] : merged.length
+      const candidate = merged.slice(start, end).trim()
+      if (candidate.length === 0) {
+        orderedMatch = false
+        break
+      }
+      expanded.push(candidate)
+    }
+  }
+
+  if (orderedMatch && expanded.length === originalLines.length) {
+    return expanded
+  }
+
+  const semicolonSplit = merged
+    .split(/;\s+/)
+    .map((line, idx, arr) => {
+      if (idx < arr.length - 1 && !line.endsWith(";")) {
+        return `${line};`
+      }
+      return line
+    })
+    .map((line) => line.trim())
+    .filter((line) => line.length > 0)
+
+  if (semicolonSplit.length === originalLines.length) {
+    return semicolonSplit
+  }
+
+  return replacementLines
+}
+
+export function restoreIndentForPairedReplacement(
+  originalLines: string[],
+  replacementLines: string[]
+): string[] {
+  if (originalLines.length !== replacementLines.length) {
+    return replacementLines
+  }
+
+  return replacementLines.map((line, idx) => {
+    if (line.length === 0) return line
+    if (leadingWhitespace(line).length > 0) return line
+    const indent = leadingWhitespace(originalLines[idx])
+    if (indent.length === 0) return line
+    return `${indent}${line}`
+  })
+}
+
+export function autocorrectReplacementLines(
+  originalLines: string[],
+  replacementLines: string[]
+): string[] {
+  let next = replacementLines
+  next = maybeExpandSingleLineMerge(originalLines, next)
+  next = restoreOldWrappedLines(originalLines, next)
+  next = restoreIndentForPairedReplacement(originalLines, next)
+  return next
+}
--- a/src/tools/hashline-edit/edit-deduplication.ts
+++ b/src/tools/hashline-edit/edit-deduplication.ts
@@ -0,0 +1,47 @@
+import type { HashlineEdit } from "./types"
+import { toNewLines } from "./edit-text-normalization"
+
+function normalizeEditPayload(payload: string | string[]): string {
+  return toNewLines(payload).join("\n")
+}
+
+function buildDedupeKey(edit: HashlineEdit): string {
+  switch (edit.type) {
+    case "set_line":
+      return `set_line|${edit.line}|${normalizeEditPayload(edit.text)}`
+    case "replace_lines":
+      return `replace_lines|${edit.start_line}|${edit.end_line}|${normalizeEditPayload(edit.text)}`
+    case "insert_after":
+      return `insert_after|${edit.line}|${normalizeEditPayload(edit.text)}`
+    case "insert_before":
+      return `insert_before|${edit.line}|${normalizeEditPayload(edit.text)}`
+    case "insert_between":
+      return `insert_between|${edit.after_line}|${edit.before_line}|${normalizeEditPayload(edit.text)}`
+    case "replace":
+      return `replace|${edit.old_text}|${normalizeEditPayload(edit.new_text)}`
+    case "append":
+      return `append|${normalizeEditPayload(edit.text)}`
+    case "prepend":
+      return `prepend|${normalizeEditPayload(edit.text)}`
+    default:
+      return JSON.stringify(edit)
+  }
+}
+
+export function dedupeEdits(edits: HashlineEdit[]): { edits: HashlineEdit[]; deduplicatedEdits: number } {
+  const seen = new Set<string>()
+  const deduped: HashlineEdit[] = []
+  let deduplicatedEdits = 0
+
+  for (const edit of edits) {
+    const key = buildDedupeKey(edit)
+    if (seen.has(key)) {
+      deduplicatedEdits += 1
+      continue
+    }
+    seen.add(key)
+    deduped.push(edit)
+  }
+
+  return { edits: deduped, deduplicatedEdits }
+}
--- a/src/tools/hashline-edit/edit-operation-primitives.ts
+++ b/src/tools/hashline-edit/edit-operation-primitives.ts
@@ -0,0 +1,160 @@
+import { autocorrectReplacementLines } from "./autocorrect-replacement-lines"
+import {
+  restoreLeadingIndent,
+  stripInsertAnchorEcho,
+  stripInsertBeforeEcho,
+  stripInsertBoundaryEcho,
+  stripRangeBoundaryEcho,
+  toNewLines,
+} from "./edit-text-normalization"
+import { parseLineRef, validateLineRef } from "./validation"
+
+interface EditApplyOptions {
+  skipValidation?: boolean
+}
+
+function shouldValidate(options?: EditApplyOptions): boolean {
+  return options?.skipValidation !== true
+}
+
+export function applySetLine(
+  lines: string[],
+  anchor: string,
+  newText: string | string[],
+  options?: EditApplyOptions
+): string[] {
+  if (shouldValidate(options)) validateLineRef(lines, anchor)
+  const { line } = parseLineRef(anchor)
+  const result = [...lines]
+  const originalLine = lines[line - 1] ?? ""
+  const corrected = autocorrectReplacementLines([originalLine], toNewLines(newText))
+  const replacement = corrected.map((entry, idx) => {
+    if (idx !== 0) return entry
+    return restoreLeadingIndent(originalLine, entry)
+  })
+  result.splice(line - 1, 1, ...replacement)
+  return result
+}
+
+export function applyReplaceLines(
+  lines: string[],
+  startAnchor: string,
+  endAnchor: string,
+  newText: string | string[],
+  options?: EditApplyOptions
+): string[] {
+  if (shouldValidate(options)) {
+    validateLineRef(lines, startAnchor)
+    validateLineRef(lines, endAnchor)
+  }
+
+  const { line: startLine } = parseLineRef(startAnchor)
+  const { line: endLine } = parseLineRef(endAnchor)
+
+  if (startLine > endLine) {
+    throw new Error(
+      `Invalid range: start line ${startLine} cannot be greater than end line ${endLine}`
+    )
+  }
+
+  const result = [...lines]
+  const originalRange = lines.slice(startLine - 1, endLine)
+  const stripped = stripRangeBoundaryEcho(lines, startLine, endLine, toNewLines(newText))
+  const corrected = autocorrectReplacementLines(originalRange, stripped)
+  const restored = corrected.map((entry, idx) => {
+    if (idx !== 0) return entry
+    return restoreLeadingIndent(lines[startLine - 1], entry)
+  })
+  result.splice(startLine - 1, endLine - startLine + 1, ...restored)
+  return result
+}
+
+export function applyInsertAfter(
+  lines: string[],
+  anchor: string,
+  text: string | string[],
+  options?: EditApplyOptions
+): string[] {
+  if (shouldValidate(options)) validateLineRef(lines, anchor)
+  const { line } = parseLineRef(anchor)
+  const result = [...lines]
+  const newLines = stripInsertAnchorEcho(lines[line - 1], toNewLines(text))
+  if (newLines.length === 0) {
+    throw new Error(`insert_after requires non-empty text for ${anchor}`)
+  }
+  result.splice(line, 0, ...newLines)
+  return result
+}
+
+export function applyInsertBefore(
+  lines: string[],
+  anchor: string,
+  text: string | string[],
+  options?: EditApplyOptions
+): string[] {
+  if (shouldValidate(options)) validateLineRef(lines, anchor)
+  const { line } = parseLineRef(anchor)
+  const result = [...lines]
+  const newLines = stripInsertBeforeEcho(lines[line - 1], toNewLines(text))
+  if (newLines.length === 0) {
+    throw new Error(`insert_before requires non-empty text for ${anchor}`)
+  }
+  result.splice(line - 1, 0, ...newLines)
+  return result
+}
+
+export function applyInsertBetween(
+  lines: string[],
+  afterAnchor: string,
+  beforeAnchor: string,
+  text: string | string[],
+  options?: EditApplyOptions
+): string[] {
+  if (shouldValidate(options)) {
+    validateLineRef(lines, afterAnchor)
+    validateLineRef(lines, beforeAnchor)
+  }
+  const { line: afterLine } = parseLineRef(afterAnchor)
+  const { line: beforeLine } = parseLineRef(beforeAnchor)
+  if (beforeLine <= afterLine) {
+    throw new Error(`insert_between requires after_line (${afterLine}) < before_line (${beforeLine})`)
+  }
+
+  const result = [...lines]
+  const newLines = stripInsertBoundaryEcho(lines[afterLine - 1], lines[beforeLine - 1], toNewLines(text))
+  if (newLines.length === 0) {
+    throw new Error(`insert_between requires non-empty text for ${afterAnchor}..${beforeAnchor}`)
+  }
+  result.splice(beforeLine - 1, 0, ...newLines)
+  return result
+}
+
+export function applyAppend(lines: string[], text: string | string[]): string[] {
+  const normalized = toNewLines(text)
+  if (normalized.length === 0) {
+    throw new Error("append requires non-empty text")
+  }
+  if (lines.length === 1 && lines[0] === "") {
+    return [...normalized]
+  }
+  return [...lines, ...normalized]
+}
+
+export function applyPrepend(lines: string[], text: string | string[]): string[] {
+  const normalized = toNewLines(text)
+  if (normalized.length === 0) {
+    throw new Error("prepend requires non-empty text")
+  }
+  if (lines.length === 1 && lines[0] === "") {
+    return [...normalized]
+  }
+  return [...normalized, ...lines]
+}
+
+export function applyReplace(content: string, oldText: string, newText: string | string[]): string {
+  if (!content.includes(oldText)) {
+    throw new Error(`Text not found: "${oldText}"`)
+  }
+  const replacement = Array.isArray(newText) ? newText.join("\n") : newText
+  return content.replaceAll(oldText, replacement)
+}
--- a/src/tools/hashline-edit/edit-operations.test.ts
+++ b/src/tools/hashline-edit/edit-operations.test.ts
@@ -1,5 +1,6 @@
 import { describe, expect, it } from "bun:test"
 import { applyHashlineEdits, applyInsertAfter, applyReplace, applyReplaceLines, applySetLine } from "./edit-operations"
+import { applyAppend, applyPrepend } from "./edit-operation-primitives"
 import { computeLineHash } from "./hash-computation"
 import type { HashlineEdit } from "./types"

@@ -246,6 +247,124 @@ describe("hashline edit operations", () => {
    const result = applyReplaceLines(lines, anchorFor(lines, 2), anchorFor(lines, 3), ["return 3", "return 4"])

    //#then
-    expect(result).toEqual(["if (x) {", "  return 3", "return 4", "}"])
+    expect(result).toEqual(["if (x) {", "  return 3", "  return 4", "}"])
+  })
+
+  it("collapses wrapped replacement span back to unique original single line", () => {
+    //#given
+    const lines = [
+      "const request = buildRequest({ method: \"GET\", retries: 3 })",
+      "const done = true",
+    ]
+
+    //#when
+    const result = applyReplaceLines(
+      lines,
+      anchorFor(lines, 1),
+      anchorFor(lines, 1),
+      ["const request = buildRequest({", "method: \"GET\", retries: 3 })"]
+    )
+
+    //#then
+    expect(result).toEqual([
+      "const request = buildRequest({ method: \"GET\", retries: 3 })",
+      "const done = true",
+    ])
+  })
+
+  it("keeps wrapped replacement when canonical match is not unique in original lines", () => {
+    //#given
+    const lines = ["const query = a + b", "const query = a+b", "const done = true"]
+
+    //#when
+    const result = applyReplaceLines(lines, anchorFor(lines, 1), anchorFor(lines, 2), ["const query = a +", "b"])
+
+    //#then
+    expect(result).toEqual(["const query = a +", "b", "const done = true"])
+  })
+
+  it("keeps wrapped replacement when same canonical candidate appears multiple times", () => {
+    //#given
+    const lines = ["const expression = alpha + beta + gamma", "const done = true"]
+
+    //#when
+    const result = applyReplaceLines(lines, anchorFor(lines, 1), anchorFor(lines, 1), [
+      "const expression = alpha +",
+      "beta + gamma",
+      "const expression = alpha +",
+      "beta + gamma",
+    ])
+
+    //#then
+    expect(result).toEqual([
+      "const expression = alpha +",
+      "beta + gamma",
+      "const expression = alpha +",
+      "beta + gamma",
+      "const done = true",
+    ])
+  })
+
+  it("keeps wrapped replacement when canonical match is shorter than threshold", () => {
+    //#given
+    const lines = ["a + b", "const done = true"]
+
+    //#when
+    const result = applyReplaceLines(lines, anchorFor(lines, 1), anchorFor(lines, 1), ["a +", "b"])
+
+    //#then
+    expect(result).toEqual(["a +", "b", "const done = true"])
+  })
+
+  it("applies append and prepend operations", () => {
+    //#given
+    const content = "line 1\nline 2"
+
+    //#when
+    const result = applyHashlineEdits(content, [
+      { type: "append", text: ["line 3"] },
+      { type: "prepend", text: ["line 0"] },
+    ])
+
+    //#then
+    expect(result).toEqual("line 0\nline 1\nline 2\nline 3")
+  })
+
+  it("appends to empty file without extra blank line", () => {
+    //#given
+    const lines = [""]
+
+    //#when
+    const result = applyAppend(lines, ["line1"])
+
+    //#then
+    expect(result).toEqual(["line1"])
+  })
+
+  it("prepends to empty file without extra blank line", () => {
+    //#given
+    const lines = [""]
+
+    //#when
+    const result = applyPrepend(lines, ["line1"])
+
+    //#then
+    expect(result).toEqual(["line1"])
+  })
+
+  it("autocorrects single-line merged replacement into original line count", () => {
+    //#given
+    const lines = ["const a = 1;", "const b = 2;"]
+
+    //#when
+    const result = applyReplaceLines(
+      lines,
+      anchorFor(lines, 1),
+      anchorFor(lines, 2),
+      "const a = 10; const b = 20;"
+    )
+
+    //#then
+    expect(result).toEqual(["const a = 10;", "const b = 20;"])
  })
 })
--- a/src/tools/hashline-edit/edit-operations.ts
+++ b/src/tools/hashline-edit/edit-operations.ts
@@ -1,13 +1,17 @@
-import { parseLineRef, validateLineRef, validateLineRefs } from "./validation"
+import { dedupeEdits } from "./edit-deduplication"
+import { collectLineRefs, getEditLineNumber } from "./edit-ordering"
 import type { HashlineEdit } from "./types"
 import {
-  restoreLeadingIndent,
-  stripInsertAnchorEcho,
-  stripInsertBeforeEcho,
-  stripInsertBoundaryEcho,
-  stripRangeBoundaryEcho,
-  toNewLines,
-} from "./edit-text-normalization"
+  applyAppend,
+  applyInsertAfter,
+  applyInsertBefore,
+  applyInsertBetween,
+  applyPrepend,
+  applyReplace,
+  applyReplaceLines,
+  applySetLine,
+} from "./edit-operation-primitives"
+import { validateLineRefs } from "./validation"

 export interface HashlineApplyReport {
  content: string
@@ -15,158 +19,6 @@ export interface HashlineApplyReport {
  deduplicatedEdits: number
 }

-export function applySetLine(lines: string[], anchor: string, newText: string | string[]): string[] {
-  validateLineRef(lines, anchor)
-  const { line } = parseLineRef(anchor)
-  const result = [...lines]
-  const replacement = toNewLines(newText).map((entry, idx) => {
-    if (idx !== 0) return entry
-    return restoreLeadingIndent(lines[line - 1], entry)
-  })
-  result.splice(line - 1, 1, ...replacement)
-  return result
-}
-
-export function applyReplaceLines(
-  lines: string[],
-  startAnchor: string,
-  endAnchor: string,
-  newText: string | string[]
-): string[] {
-  validateLineRef(lines, startAnchor)
-  validateLineRef(lines, endAnchor)
-
-  const { line: startLine } = parseLineRef(startAnchor)
-  const { line: endLine } = parseLineRef(endAnchor)
-
-  if (startLine > endLine) {
-    throw new Error(
-      `Invalid range: start line ${startLine} cannot be greater than end line ${endLine}`
-    )
-  }
-
-  const result = [...lines]
-  const stripped = stripRangeBoundaryEcho(lines, startLine, endLine, toNewLines(newText))
-  const restored = stripped.map((entry, idx) => {
-    if (idx !== 0) return entry
-    return restoreLeadingIndent(lines[startLine - 1], entry)
-  })
-  result.splice(startLine - 1, endLine - startLine + 1, ...restored)
-  return result
-}
-
-export function applyInsertAfter(lines: string[], anchor: string, text: string | string[]): string[] {
-  validateLineRef(lines, anchor)
-  const { line } = parseLineRef(anchor)
-  const result = [...lines]
-  const newLines = stripInsertAnchorEcho(lines[line - 1], toNewLines(text))
-  if (newLines.length === 0) {
-    throw new Error(`insert_after requires non-empty text for ${anchor}`)
-  }
-  result.splice(line, 0, ...newLines)
-  return result
-}
-
-export function applyInsertBefore(lines: string[], anchor: string, text: string | string[]): string[] {
-  validateLineRef(lines, anchor)
-  const { line } = parseLineRef(anchor)
-  const result = [...lines]
-  const newLines = stripInsertBeforeEcho(lines[line - 1], toNewLines(text))
-  if (newLines.length === 0) {
-    throw new Error(`insert_before requires non-empty text for ${anchor}`)
-  }
-  result.splice(line - 1, 0, ...newLines)
-  return result
-}
-
-export function applyInsertBetween(
-  lines: string[],
-  afterAnchor: string,
-  beforeAnchor: string,
-  text: string | string[]
-): string[] {
-  validateLineRef(lines, afterAnchor)
-  validateLineRef(lines, beforeAnchor)
-  const { line: afterLine } = parseLineRef(afterAnchor)
-  const { line: beforeLine } = parseLineRef(beforeAnchor)
-  if (beforeLine <= afterLine) {
-    throw new Error(`insert_between requires after_line (${afterLine}) < before_line (${beforeLine})`)
-  }
-
-  const result = [...lines]
-  const newLines = stripInsertBoundaryEcho(lines[afterLine - 1], lines[beforeLine - 1], toNewLines(text))
-  if (newLines.length === 0) {
-    throw new Error(`insert_between requires non-empty text for ${afterAnchor}..${beforeAnchor}`)
-  }
-  result.splice(beforeLine - 1, 0, ...newLines)
-  return result
-}
-
-export function applyReplace(content: string, oldText: string, newText: string | string[]): string {
-  if (!content.includes(oldText)) {
-    throw new Error(`Text not found: "${oldText}"`)
-  }
-  const replacement = Array.isArray(newText) ? newText.join("\n") : newText
-  return content.replaceAll(oldText, replacement)
-}
-
-function getEditLineNumber(edit: HashlineEdit): number {
-  switch (edit.type) {
-    case "set_line":
-      return parseLineRef(edit.line).line
-    case "replace_lines":
-      return parseLineRef(edit.end_line).line
-    case "insert_after":
-      return parseLineRef(edit.line).line
-    case "insert_before":
-      return parseLineRef(edit.line).line
-    case "insert_between":
-      return parseLineRef(edit.before_line).line
-    case "replace":
-      return Number.NEGATIVE_INFINITY
-    default:
-      return Number.POSITIVE_INFINITY
-  }
-}
-
-function normalizeEditPayload(payload: string | string[]): string {
-  return toNewLines(payload).join("\n")
-}
-
-function dedupeEdits(edits: HashlineEdit[]): { edits: HashlineEdit[]; deduplicatedEdits: number } {
-  const seen = new Set<string>()
-  const deduped: HashlineEdit[] = []
-  let deduplicatedEdits = 0
-
-  for (const edit of edits) {
-    const key = (() => {
-      switch (edit.type) {
-        case "set_line":
-          return `set_line|${edit.line}|${normalizeEditPayload(edit.text)}`
-        case "replace_lines":
-          return `replace_lines|${edit.start_line}|${edit.end_line}|${normalizeEditPayload(edit.text)}`
-        case "insert_after":
-          return `insert_after|${edit.line}|${normalizeEditPayload(edit.text)}`
-        case "insert_before":
-          return `insert_before|${edit.line}|${normalizeEditPayload(edit.text)}`
-        case "insert_between":
-          return `insert_between|${edit.after_line}|${edit.before_line}|${normalizeEditPayload(edit.text)}`
-        case "replace":
-          return `replace|${edit.old_text}|${normalizeEditPayload(edit.new_text)}`
-      }
-    })()
-
-    if (seen.has(key)) {
-      deduplicatedEdits += 1
-      continue
-    }
-    seen.add(key)
-    deduped.push(edit)
-  }
-
-  return { edits: deduped, deduplicatedEdits }
-}
-
 export function applyHashlineEditsWithReport(content: string, edits: HashlineEdit[]): HashlineApplyReport {
  if (edits.length === 0) {
    return {
@@ -182,40 +34,23 @@ export function applyHashlineEditsWithReport(content: string, edits: HashlineEdi
  let noopEdits = 0

  let result = content
-  let lines = result.split("\n")
+  let lines = result.length === 0 ? [] : result.split("\n")

-  const refs = sortedEdits.flatMap((edit) => {
-    switch (edit.type) {
-      case "set_line":
-        return [edit.line]
-      case "replace_lines":
-        return [edit.start_line, edit.end_line]
-      case "insert_after":
-        return [edit.line]
-      case "insert_before":
-        return [edit.line]
-      case "insert_between":
-        return [edit.after_line, edit.before_line]
-      case "replace":
-        return []
-      default:
-        return []
-    }
-  })
+  const refs = collectLineRefs(sortedEdits)
  validateLineRefs(lines, refs)

  for (const edit of sortedEdits) {
    switch (edit.type) {
      case "set_line": {
-        lines = applySetLine(lines, edit.line, edit.text)
+        lines = applySetLine(lines, edit.line, edit.text, { skipValidation: true })
        break
      }
      case "replace_lines": {
-        lines = applyReplaceLines(lines, edit.start_line, edit.end_line, edit.text)
+        lines = applyReplaceLines(lines, edit.start_line, edit.end_line, edit.text, { skipValidation: true })
        break
      }
      case "insert_after": {
-        const next = applyInsertAfter(lines, edit.line, edit.text)
+        const next = applyInsertAfter(lines, edit.line, edit.text, { skipValidation: true })
        if (next.join("\n") === lines.join("\n")) {
          noopEdits += 1
          break
@@ -224,7 +59,7 @@ export function applyHashlineEditsWithReport(content: string, edits: HashlineEdi
        break
      }
      case "insert_before": {
-        const next = applyInsertBefore(lines, edit.line, edit.text)
+        const next = applyInsertBefore(lines, edit.line, edit.text, { skipValidation: true })
        if (next.join("\n") === lines.join("\n")) {
          noopEdits += 1
          break
@@ -233,7 +68,25 @@ export function applyHashlineEditsWithReport(content: string, edits: HashlineEdi
        break
      }
      case "insert_between": {
-        const next = applyInsertBetween(lines, edit.after_line, edit.before_line, edit.text)
+        const next = applyInsertBetween(lines, edit.after_line, edit.before_line, edit.text, { skipValidation: true })
+        if (next.join("\n") === lines.join("\n")) {
+          noopEdits += 1
+          break
+        }
+        lines = next
+        break
+      }
+      case "append": {
+        const next = applyAppend(lines, edit.text)
+        if (next.join("\n") === lines.join("\n")) {
+          noopEdits += 1
+          break
+        }
+        lines = next
+        break
+      }
+      case "prepend": {
+        const next = applyPrepend(lines, edit.text)
        if (next.join("\n") === lines.join("\n")) {
          noopEdits += 1
          break
@@ -243,11 +96,7 @@ export function applyHashlineEditsWithReport(content: string, edits: HashlineEdi
      }
      case "replace": {
        result = lines.join("\n")
-        if (!result.includes(edit.old_text)) {
-          throw new Error(`Text not found: "${edit.old_text}"`)
-        }
-        const replacement = Array.isArray(edit.new_text) ? edit.new_text.join("\n") : edit.new_text
-        const replaced = result.replaceAll(edit.old_text, replacement)
+        const replaced = applyReplace(result, edit.old_text, edit.new_text)
        if (replaced === result) {
          noopEdits += 1
          break
@@ -269,3 +118,12 @@ export function applyHashlineEditsWithReport(content: string, edits: HashlineEdi
 export function applyHashlineEdits(content: string, edits: HashlineEdit[]): string {
  return applyHashlineEditsWithReport(content, edits).content
 }
+
+export {
+  applySetLine,
+  applyReplaceLines,
+  applyInsertAfter,
+  applyInsertBefore,
+  applyInsertBetween,
+  applyReplace,
+} from "./edit-operation-primitives"
--- a/src/tools/hashline-edit/edit-ordering.ts
+++ b/src/tools/hashline-edit/edit-ordering.ts
@@ -0,0 +1,48 @@
+import { parseLineRef } from "./validation"
+import type { HashlineEdit } from "./types"
+
+export function getEditLineNumber(edit: HashlineEdit): number {
+  switch (edit.type) {
+    case "set_line":
+      return parseLineRef(edit.line).line
+    case "replace_lines":
+      return parseLineRef(edit.end_line).line
+    case "insert_after":
+      return parseLineRef(edit.line).line
+    case "insert_before":
+      return parseLineRef(edit.line).line
+    case "insert_between":
+      return parseLineRef(edit.before_line).line
+    case "append":
+      return Number.NEGATIVE_INFINITY
+    case "prepend":
+      return Number.NEGATIVE_INFINITY
+    case "replace":
+      return Number.NEGATIVE_INFINITY
+    default:
+      return Number.POSITIVE_INFINITY
+  }
+}
+
+export function collectLineRefs(edits: HashlineEdit[]): string[] {
+  return edits.flatMap((edit) => {
+    switch (edit.type) {
+      case "set_line":
+        return [edit.line]
+      case "replace_lines":
+        return [edit.start_line, edit.end_line]
+      case "insert_after":
+        return [edit.line]
+      case "insert_before":
+        return [edit.line]
+      case "insert_between":
+        return [edit.after_line, edit.before_line]
+      case "append":
+      case "prepend":
+      case "replace":
+        return []
+      default:
+        return []
+    }
+  })
+}
--- a/src/tools/hashline-edit/file-text-canonicalization.ts
+++ b/src/tools/hashline-edit/file-text-canonicalization.ts
@@ -0,0 +1,44 @@
+export interface FileTextEnvelope {
+  content: string
+  hadBom: boolean
+  lineEnding: "\n" | "\r\n"
+}
+
+function detectLineEnding(content: string): "\n" | "\r\n" {
+  const crlfIndex = content.indexOf("\r\n")
+  const lfIndex = content.indexOf("\n")
+  if (lfIndex === -1) return "\n"
+  if (crlfIndex === -1) return "\n"
+  return crlfIndex < lfIndex ? "\r\n" : "\n"
+}
+
+function stripBom(content: string): { content: string; hadBom: boolean } {
+  if (!content.startsWith("\uFEFF")) {
+    return { content, hadBom: false }
+  }
+  return { content: content.slice(1), hadBom: true }
+}
+
+function normalizeToLf(content: string): string {
+  return content.replace(/\r\n/g, "\n").replace(/\r/g, "\n")
+}
+
+function restoreLineEndings(content: string, lineEnding: "\n" | "\r\n"): string {
+  if (lineEnding === "\n") return content
+  return content.replace(/\n/g, "\r\n")
+}
+
+export function canonicalizeFileText(content: string): FileTextEnvelope {
+  const stripped = stripBom(content)
+  return {
+    content: normalizeToLf(stripped.content),
+    hadBom: stripped.hadBom,
+    lineEnding: detectLineEnding(stripped.content),
+  }
+}
+
+export function restoreFileText(content: string, envelope: FileTextEnvelope): string {
+  const withLineEnding = restoreLineEndings(content, envelope.lineEnding)
+  if (!envelope.hadBom) return withLineEnding
+  return `\uFEFF${withLineEnding}`
+}
--- a/src/tools/hashline-edit/hashline-edit-diff.ts
+++ b/src/tools/hashline-edit/hashline-edit-diff.ts
@@ -0,0 +1,31 @@
+import { computeLineHash } from "./hash-computation"
+
+export function generateHashlineDiff(oldContent: string, newContent: string, filePath: string): string {
+  const oldLines = oldContent.split("\n")
+  const newLines = newContent.split("\n")
+
+  let diff = `--- ${filePath}\n+++ ${filePath}\n`
+  const maxLines = Math.max(oldLines.length, newLines.length)
+
+  for (let i = 0; i < maxLines; i += 1) {
+    const oldLine = oldLines[i] ?? ""
+    const newLine = newLines[i] ?? ""
+    const lineNum = i + 1
+    const hash = computeLineHash(lineNum, newLine)
+
+    if (i >= oldLines.length) {
+      diff += `+ ${lineNum}#${hash}:${newLine}\n`
+      continue
+    }
+    if (i >= newLines.length) {
+      diff += `- ${lineNum}#  :${oldLine}\n`
+      continue
+    }
+    if (oldLine !== newLine) {
+      diff += `- ${lineNum}#  :${oldLine}\n`
+      diff += `+ ${lineNum}#${hash}:${newLine}\n`
+    }
+  }
+
+  return diff
+}
--- a/src/tools/hashline-edit/hashline-edit-executor.ts
+++ b/src/tools/hashline-edit/hashline-edit-executor.ts
@@ -0,0 +1,146 @@
+import type { ToolContext } from "@opencode-ai/plugin/tool"
+import { storeToolMetadata } from "../../features/tool-metadata-store"
+import { applyHashlineEditsWithReport } from "./edit-operations"
+import { countLineDiffs, generateUnifiedDiff, toHashlineContent } from "./diff-utils"
+import { canonicalizeFileText, restoreFileText } from "./file-text-canonicalization"
+import { generateHashlineDiff } from "./hashline-edit-diff"
+import type { HashlineEdit } from "./types"
+
+interface HashlineEditArgs {
+  filePath: string
+  edits: HashlineEdit[]
+  delete?: boolean
+  rename?: string
+}
+
+type ToolContextWithCallID = ToolContext & {
+  callID?: string
+  callId?: string
+  call_id?: string
+}
+
+type ToolContextWithMetadata = ToolContextWithCallID & {
+  metadata?: (value: unknown) => void
+}
+
+function resolveToolCallID(ctx: ToolContextWithCallID): string | undefined {
+  if (typeof ctx.callID === "string" && ctx.callID.trim() !== "") return ctx.callID
+  if (typeof ctx.callId === "string" && ctx.callId.trim() !== "") return ctx.callId
+  if (typeof ctx.call_id === "string" && ctx.call_id.trim() !== "") return ctx.call_id
+  return undefined
+}
+
+function canCreateFromMissingFile(edits: HashlineEdit[]): boolean {
+  if (edits.length === 0) return false
+  return edits.every((edit) => edit.type === "append" || edit.type === "prepend")
+}
+
+function buildSuccessMeta(
+  effectivePath: string,
+  beforeContent: string,
+  afterContent: string,
+  noopEdits: number,
+  deduplicatedEdits: number
+) {
+  const unifiedDiff = generateUnifiedDiff(beforeContent, afterContent, effectivePath)
+  const { additions, deletions } = countLineDiffs(beforeContent, afterContent)
+
+  return {
+    title: effectivePath,
+    metadata: {
+      filePath: effectivePath,
+      path: effectivePath,
+      file: effectivePath,
+      diff: unifiedDiff,
+      noopEdits,
+      deduplicatedEdits,
+      filediff: {
+        file: effectivePath,
+        path: effectivePath,
+        filePath: effectivePath,
+        before: beforeContent,
+        after: afterContent,
+        additions,
+        deletions,
+      },
+    },
+  }
+}
+
+export async function executeHashlineEditTool(args: HashlineEditArgs, context: ToolContext): Promise<string> {
+  try {
+    const metadataContext = context as ToolContextWithMetadata
+    const filePath = args.filePath
+    const { edits, delete: deleteMode, rename } = args
+
+    if (deleteMode && rename) {
+      return "Error: delete and rename cannot be used together"
+    }
+    if (!deleteMode && (!edits || !Array.isArray(edits) || edits.length === 0)) {
+      return "Error: edits parameter must be a non-empty array"
+    }
+    if (deleteMode && edits.length > 0) {
+      return "Error: delete mode requires edits to be an empty array"
+    }
+
+    const file = Bun.file(filePath)
+    const exists = await file.exists()
+    if (!exists && !deleteMode && !canCreateFromMissingFile(edits)) {
+      return `Error: File not found: ${filePath}`
+    }
+
+    if (deleteMode) {
+      if (!exists) return `Error: File not found: ${filePath}`
+      await Bun.file(filePath).delete()
+      return `Successfully deleted ${filePath}`
+    }
+
+    const rawOldContent = exists ? Buffer.from(await file.arrayBuffer()).toString("utf8") : ""
+    const oldEnvelope = canonicalizeFileText(rawOldContent)
+
+    const applyResult = applyHashlineEditsWithReport(oldEnvelope.content, edits)
+    const canonicalNewContent = applyResult.content
+    const writeContent = restoreFileText(canonicalNewContent, oldEnvelope)
+
+    await Bun.write(filePath, writeContent)
+
+    if (rename && rename !== filePath) {
+      await Bun.write(rename, writeContent)
+      await Bun.file(filePath).delete()
+    }
+
+    const effectivePath = rename && rename !== filePath ? rename : filePath
+    const diff = generateHashlineDiff(oldEnvelope.content, canonicalNewContent, effectivePath)
+    const newHashlined = toHashlineContent(canonicalNewContent)
+    const meta = buildSuccessMeta(
+      effectivePath,
+      oldEnvelope.content,
+      canonicalNewContent,
+      applyResult.noopEdits,
+      applyResult.deduplicatedEdits
+    )
+
+    if (typeof metadataContext.metadata === "function") {
+      metadataContext.metadata(meta)
+    }
+
+    const callID = resolveToolCallID(metadataContext)
+    if (callID) {
+      storeToolMetadata(context.sessionID, callID, meta)
+    }
+
+    return `Successfully applied ${edits.length} edit(s) to ${effectivePath}
+No-op edits: ${applyResult.noopEdits}, deduplicated edits: ${applyResult.deduplicatedEdits}
+
+${diff}
+
+Updated file (LINE#ID:content):
+${newHashlined}`
+  } catch (error) {
+    const message = error instanceof Error ? error.message : String(error)
+    if (message.toLowerCase().includes("hash")) {
+      return `Error: hash mismatch - ${message}\nTip: reuse LINE#ID entries from the latest read/edit output, or batch related edits in one call.`
+    }
+    return `Error: ${message}`
+  }
+}
--- a/src/tools/hashline-edit/index.ts
+++ b/src/tools/hashline-edit/index.ts
@@ -7,7 +7,17 @@ export {
 } from "./hash-computation"
 export { parseLineRef, validateLineRef } from "./validation"
 export type { LineRef } from "./validation"
-export type { SetLine, ReplaceLines, InsertAfter, InsertBefore, InsertBetween, Replace, HashlineEdit } from "./types"
+export type {
+  SetLine,
+  ReplaceLines,
+  InsertAfter,
+  InsertBefore,
+  InsertBetween,
+  Replace,
+  Append,
+  Prepend,
+  HashlineEdit,
+} from "./types"
 export { NIBBLE_STR, HASHLINE_DICT, HASHLINE_REF_PATTERN, HASHLINE_OUTPUT_PATTERN } from "./constants"
 export {
  applyHashlineEdits,
--- a/src/tools/hashline-edit/tool-description.ts
+++ b/src/tools/hashline-edit/tool-description.ts
@@ -1,34 +1,70 @@
 export const HASHLINE_EDIT_DESCRIPTION = `Edit files using LINE#ID format for precise, safe modifications.

 WORKFLOW:
-1. Read the file and copy exact LINE#ID anchors.
-2. Submit one edit call with all related operations for that file.
-3. If more edits are needed after success, use the latest anchors from read/edit output.
-4. Use anchors as "LINE#ID" only (never include trailing ":content").
+1. Read target file/range and copy exact LINE#ID tags.
+2. Pick the smallest operation per logical mutation site.
+3. Submit one edit call per file with all related operations.
+4. If same file needs another call, re-read first.
+5. Use anchors as "LINE#ID" only (never include trailing ":content").

 VALIDATION:
- Payload shape: { "filePath": string, "edits": [...], "delete"?: boolean, "rename"?: string }
- Each edit must be one of: set_line, replace_lines, insert_after, insert_before, insert_between, replace
- text/new_text must contain plain replacement text only (no LINE#ID prefixes, no diff + markers)
+ Payload shape: { "filePath": string, "edits": [...], "delete"?: boolean, "rename"?: string }
+ Each edit must be one of: set_line, replace_lines, insert_after, insert_before, insert_between, replace, append, prepend
+ text/new_text must contain plain replacement text only (no LINE#ID prefixes, no diff + markers)
+ CRITICAL: all operations validate against the same pre-edit file snapshot and apply bottom-up. Refs/tags are interpreted against the last-read version of the file.

-LINE#ID FORMAT (CRITICAL - READ CAREFULLY):
-Each line reference must be in "LINE#ID" format where:
- LINE: 1-based line number
- ID: Two CID letters from the set ZPMQVRWSNKTXJBYH
-
-OPERATION TYPES:
-1. set_line
-2. replace_lines
-3. insert_after
-4. insert_before
-5. insert_between
-6. replace
+LINE#ID FORMAT (CRITICAL):
+ Each line reference must be in "LINE#ID" format where:
+ LINE: 1-based line number
+ ID: Two CID letters from the set ZPMQVRWSNKTXJBYH

 FILE MODES:
- delete=true deletes file and requires edits=[] with no rename
- rename moves final content to a new path and removes old path
+ delete=true deletes file and requires edits=[] with no rename
+ rename moves final content to a new path and removes old path

 CONTENT FORMAT:
- text/new_text can be a string (single line) or string[] (multi-line, preferred).
- If you pass a multi-line string, it is split by real newline characters.
- Literal "\\n" is preserved as text.`
+ text/new_text can be a string (single line) or string[] (multi-line, preferred).
+ If you pass a multi-line string, it is split by real newline characters.
+ Literal "\\n" is preserved as text.
+
+FILE CREATION:
+ append: adds content at EOF. If file does not exist, creates it.
+ prepend: adds content at BOF. If file does not exist, creates it.
+ CRITICAL: append/prepend are the only operations that work without an existing file.
+
+OPERATION CHOICE:
+ One line wrong -> set_line
+ Adjacent block rewrite or swap/move -> replace_lines (prefer one range op over many single-line ops)
+ Both boundaries known -> insert_between (ALWAYS prefer over insert_after/insert_before)
+ One boundary known -> insert_after or insert_before
+ New file or EOF/BOF addition -> append or prepend
+ No LINE#ID available -> replace (last resort)
+
+RULES (CRITICAL):
+ 1. Minimize scope: one logical mutation site per operation.
+ 2. Preserve formatting: keep indentation, punctuation, line breaks, trailing commas, brace style.
+ 3. Prefer insertion over neighbor rewrites: anchor to structural boundaries (}, ], },), not interior property lines.
+ 4. No no-ops: replacement content must differ from current content.
+ 5. Touch only requested code: avoid incidental edits.
+ 6. Use exact current tokens: NEVER rewrite approximately.
+ 7. For swaps/moves: prefer one range operation over multiple single-line operations.
+ 8. Output tool calls only; no prose or commentary between them.
+
+TAG CHOICE (ALWAYS):
+ - Copy tags exactly from read output or >>> mismatch output.
+ - NEVER guess tags.
+ - Prefer insert_between over insert_after/insert_before when both boundaries are known.
+ - Anchor to structural lines (function/class/brace), NEVER blank lines.
+ - Anti-pattern warning: blank/whitespace anchors are fragile.
+ - Re-read after each successful edit call before issuing another on the same file.
+
+AUTOCORRECT (built-in - you do NOT need to handle these):
+ Merged lines are auto-expanded back to original line count.
+ Indentation is auto-restored from original lines.
+ BOM and CRLF line endings are preserved automatically.
+ Hashline prefixes and diff markers in text are auto-stripped.
+
+RECOVERY (when >>> mismatch error appears):
+ Copy the updated LINE#ID tags shown in the error output directly.
+ Re-read only if the needed tags are missing from the error snippet.
+ ALWAYS batch all edits for one file in a single call.`
--- a/src/tools/hashline-edit/tools.test.ts
+++ b/src/tools/hashline-edit/tools.test.ts
@@ -2,6 +2,7 @@ import { describe, it, expect, beforeEach, afterEach, mock } from "bun:test"
 import type { ToolContext } from "@opencode-ai/plugin/tool"
 import { createHashlineEditTool } from "./tools"
 import { computeLineHash } from "./hash-computation"
+import { canonicalizeFileText } from "./file-text-canonicalization"
 import * as fs from "node:fs"
 import * as os from "node:os"
 import * as path from "node:path"
@@ -216,4 +217,72 @@ describe("createHashlineEditTool", () => {
    expect(fs.existsSync(filePath)).toBe(false)
    expect(result).toContain("Successfully deleted")
  })
+
+  it("creates missing file with append and prepend", async () => {
+    //#given
+    const filePath = path.join(tempDir, "created.txt")
+
+    //#when
+    const result = await tool.execute(
+      {
+        filePath,
+        edits: [
+          { type: "append", text: ["line2"] },
+          { type: "prepend", text: ["line1"] },
+        ],
+      },
+      createMockContext(),
+    )
+
+    //#then
+    expect(fs.existsSync(filePath)).toBe(true)
+    expect(fs.readFileSync(filePath, "utf-8")).toBe("line1\nline2")
+    expect(result).toContain("Successfully applied 2 edit(s)")
+  })
+
+  it("preserves BOM and CRLF through hashline_edit", async () => {
+    //#given
+    const filePath = path.join(tempDir, "crlf-bom.txt")
+    const bomCrLf = "\uFEFFline1\r\nline2\r\n"
+    fs.writeFileSync(filePath, bomCrLf)
+    const line2Hash = computeLineHash(2, "line2")
+
+    //#when
+    await tool.execute(
+      {
+        filePath,
+        edits: [{ type: "set_line", line: `2#${line2Hash}`, text: "line2-updated" }],
+      },
+      createMockContext(),
+    )
+
+    //#then
+    const bytes = fs.readFileSync(filePath)
+    expect(bytes[0]).toBe(0xef)
+    expect(bytes[1]).toBe(0xbb)
+    expect(bytes[2]).toBe(0xbf)
+    expect(bytes.toString("utf-8")).toBe("\uFEFFline1\r\nline2-updated\r\n")
+  })
+
+  it("detects LF as line ending when LF appears before CRLF", () => {
+    //#given
+    const content = "line1\nline2\r\nline3"
+
+    //#when
+    const envelope = canonicalizeFileText(content)
+
+    //#then
+    expect(envelope.lineEnding).toBe("\n")
+  })
+
+  it("detects CRLF as line ending when CRLF appears before LF", () => {
+    //#given
+    const content = "line1\r\nline2\nline3"
+
+    //#when
+    const envelope = canonicalizeFileText(content)
+
+    //#then
+    expect(envelope.lineEnding).toBe("\r\n")
+  })
 })
--- a/src/tools/hashline-edit/tools.ts
+++ b/src/tools/hashline-edit/tools.ts
@@ -1,9 +1,6 @@
 import { tool, type ToolContext, type ToolDefinition } from "@opencode-ai/plugin/tool"
-import { storeToolMetadata } from "../../features/tool-metadata-store"
 import type { HashlineEdit } from "./types"
-import { applyHashlineEditsWithReport } from "./edit-operations"
-import { computeLineHash } from "./hash-computation"
-import { toHashlineContent, generateUnifiedDiff, countLineDiffs } from "./diff-utils"
+import { executeHashlineEditTool } from "./hashline-edit-executor"
 import { HASHLINE_EDIT_DESCRIPTION } from "./tool-description"

 interface HashlineEditArgs {
@@ -13,49 +10,6 @@ interface HashlineEditArgs {
  rename?: string
 }

-type ToolContextWithCallID = ToolContext & {
-  callID?: string
-  callId?: string
-  call_id?: string
-}
-
-type ToolContextWithMetadata = ToolContextWithCallID & {
-  metadata?: (value: unknown) => void
-}
-
-function resolveToolCallID(ctx: ToolContextWithCallID): string | undefined {
-  if (typeof ctx.callID === "string" && ctx.callID.trim() !== "") return ctx.callID
-  if (typeof ctx.callId === "string" && ctx.callId.trim() !== "") return ctx.callId
-  if (typeof ctx.call_id === "string" && ctx.call_id.trim() !== "") return ctx.call_id
-  return undefined
-}
-
-function generateDiff(oldContent: string, newContent: string, filePath: string): string {
-  const oldLines = oldContent.split("\n")
-  const newLines = newContent.split("\n")
-
-  let diff = `--- ${filePath}\n+++ ${filePath}\n`
-
-  const maxLines = Math.max(oldLines.length, newLines.length)
-  for (let i = 0; i < maxLines; i++) {
-    const oldLine = oldLines[i] ?? ""
-    const newLine = newLines[i] ?? ""
-    const lineNum = i + 1
-    const hash = computeLineHash(lineNum, newLine)
-
-    if (i >= oldLines.length) {
-      diff += `+ ${lineNum}#${hash}:${newLine}\n`
-    } else if (i >= newLines.length) {
-      diff += `- ${lineNum}#  :${oldLine}\n`
-    } else if (oldLine !== newLine) {
-      diff += `- ${lineNum}#  :${oldLine}\n`
-      diff += `+ ${lineNum}#${hash}:${newLine}\n`
-    }
-  }
-
-  return diff
-}
-
 export function createHashlineEditTool(): ToolDefinition {
  return tool({
    description: HASHLINE_EDIT_DESCRIPTION,
@@ -110,101 +64,22 @@ export function createHashlineEditTool(): ToolDefinition {
                .union([tool.schema.string(), tool.schema.array(tool.schema.string())])
                .describe("Replacement text (string or string[] for multiline)"),
            }),
+            tool.schema.object({
+              type: tool.schema.literal("append"),
+              text: tool.schema
+                .union([tool.schema.string(), tool.schema.array(tool.schema.string())])
+                .describe("Content to append at EOF; also creates missing file"),
+            }),
+            tool.schema.object({
+              type: tool.schema.literal("prepend"),
+              text: tool.schema
+                .union([tool.schema.string(), tool.schema.array(tool.schema.string())])
+                .describe("Content to prepend at BOF; also creates missing file"),
+            }),
          ])
        )
        .describe("Array of edit operations to apply (empty when delete=true)"),
    },
-    execute: async (args: HashlineEditArgs, context: ToolContext) => {
-      try {
-        const metadataContext = context as ToolContextWithMetadata
-        const filePath = args.filePath
-        const { edits, delete: deleteMode, rename } = args
-
-        if (deleteMode && rename) {
-          return "Error: delete and rename cannot be used together"
-        }
-
-        if (!deleteMode && (!edits || !Array.isArray(edits) || edits.length === 0)) {
-          return "Error: edits parameter must be a non-empty array"
-        }
-        if (deleteMode && edits.length > 0) {
-          return "Error: delete mode requires edits to be an empty array"
-        }
-
-        const file = Bun.file(filePath)
-        const exists = await file.exists()
-        if (!exists) {
-          return `Error: File not found: ${filePath}`
-        }
-
-        if (deleteMode) {
-          await Bun.file(filePath).delete()
-          return `Successfully deleted ${filePath}`
-        }
-
-        const oldContent = await file.text()
-        const applyResult = applyHashlineEditsWithReport(oldContent, edits)
-        const newContent = applyResult.content
-
-        await Bun.write(filePath, newContent)
-
-        if (rename && rename !== filePath) {
-          await Bun.write(rename, newContent)
-          await Bun.file(filePath).delete()
-        }
-
-        const effectivePath = rename && rename !== filePath ? rename : filePath
-
-        const diff = generateDiff(oldContent, newContent, effectivePath)
-        const newHashlined = toHashlineContent(newContent)
-
-        const unifiedDiff = generateUnifiedDiff(oldContent, newContent, effectivePath)
-        const { additions, deletions } = countLineDiffs(oldContent, newContent)
-
-        const meta = {
-          title: effectivePath,
-          metadata: {
-            filePath: effectivePath,
-            path: effectivePath,
-            file: effectivePath,
-            diff: unifiedDiff,
-            noopEdits: applyResult.noopEdits,
-            deduplicatedEdits: applyResult.deduplicatedEdits,
-            filediff: {
-              file: effectivePath,
-              path: effectivePath,
-              filePath: effectivePath,
-              before: oldContent,
-              after: newContent,
-              additions,
-              deletions,
-            },
-          },
-        }
-
-        if (typeof metadataContext.metadata === "function") {
-          metadataContext.metadata(meta)
-        }
-
-        const callID = resolveToolCallID(metadataContext)
-        if (callID) {
-          storeToolMetadata(context.sessionID, callID, meta)
-        }
-
-        return `Successfully applied ${edits.length} edit(s) to ${effectivePath}
-No-op edits: ${applyResult.noopEdits}, deduplicated edits: ${applyResult.deduplicatedEdits}
-
-${diff}
-
-Updated file (LINE#ID:content):
-${newHashlined}`
-      } catch (error) {
-        const message = error instanceof Error ? error.message : String(error)
-        if (message.toLowerCase().includes("hash")) {
-          return `Error: hash mismatch - ${message}\nTip: reuse LINE#ID entries from the latest read/edit output, or batch related edits in one call.`
-        }
-        return `Error: ${message}`
-      }
-    },
+    execute: async (args: HashlineEditArgs, context: ToolContext) => executeHashlineEditTool(args, context),
  })
 }
--- a/src/tools/hashline-edit/types.ts
+++ b/src/tools/hashline-edit/types.ts
@@ -36,4 +36,22 @@ export interface Replace {
  new_text: string | string[]
 }

-export type HashlineEdit = SetLine | ReplaceLines | InsertAfter | InsertBefore | InsertBetween | Replace
+export interface Append {
+  type: "append"
+  text: string | string[]
+}
+
+export interface Prepend {
+  type: "prepend"
+  text: string | string[]
+}
+
+export type HashlineEdit =
+  | SetLine
+  | ReplaceLines
+  | InsertAfter
+  | InsertBefore
+  | InsertBetween
+  | Replace
+  | Append
+  | Prepend
--- a/src/tools/lsp/lsp-manager-process-cleanup.ts
+++ b/src/tools/lsp/lsp-manager-process-cleanup.ts
@@ -1,45 +1,71 @@
 type ManagedClientForCleanup = {
  client: {
-    stop: () => Promise<void>
-  }
-}
+    stop: () => Promise<void>;
+  };
+};

 type ProcessCleanupOptions = {
-  getClients: () => IterableIterator<[string, ManagedClientForCleanup]>
-  clearClients: () => void
-  clearCleanupInterval: () => void
-}
+  getClients: () => IterableIterator<[string, ManagedClientForCleanup]>;
+  clearClients: () => void;
+  clearCleanupInterval: () => void;
+};
+
+type RegisteredHandler = {
+  event: string;
+  listener: (...args: unknown[]) => void;
+};
+
+export type LspProcessCleanupHandle = {
+  unregister: () => void;
+};
+
+export function registerLspManagerProcessCleanup(options: ProcessCleanupOptions): LspProcessCleanupHandle {
+  const handlers: RegisteredHandler[] = [];

-export function registerLspManagerProcessCleanup(options: ProcessCleanupOptions): void {
  // Synchronous cleanup for 'exit' event (cannot await)
  const syncCleanup = () => {
    for (const [, managed] of options.getClients()) {
      try {
        // Fire-and-forget during sync exit - process is terminating
-        void managed.client.stop().catch(() => {})
+        void managed.client.stop().catch(() => {});
      } catch {}
    }
-    options.clearClients()
-    options.clearCleanupInterval()
-  }
+    options.clearClients();
+    options.clearCleanupInterval();
+  };

  // Async cleanup for signal handlers - properly await all stops
  const asyncCleanup = async () => {
-    const stopPromises: Promise<void>[] = []
+    const stopPromises: Promise<void>[] = [];
    for (const [, managed] of options.getClients()) {
-      stopPromises.push(managed.client.stop().catch(() => {}))
+      stopPromises.push(managed.client.stop().catch(() => {}));
    }
-    await Promise.allSettled(stopPromises)
-    options.clearClients()
-    options.clearCleanupInterval()
-  }
+    await Promise.allSettled(stopPromises);
+    options.clearClients();
+    options.clearCleanupInterval();
+  };

-  process.on("exit", syncCleanup)
+  const registerHandler = (event: string, listener: (...args: unknown[]) => void) => {
+    handlers.push({ event, listener });
+    process.on(event, listener);
+  };
+
+  registerHandler("exit", syncCleanup);

  // Don't call process.exit() here; other handlers (background-agent manager) handle final exit.
-  process.on("SIGINT", () => void asyncCleanup().catch(() => {}))
-  process.on("SIGTERM", () => void asyncCleanup().catch(() => {}))
+  const signalCleanup = () => void asyncCleanup().catch(() => {});
+  registerHandler("SIGINT", signalCleanup);
+  registerHandler("SIGTERM", signalCleanup);
  if (process.platform === "win32") {
-    process.on("SIGBREAK", () => void asyncCleanup().catch(() => {}))
+    registerHandler("SIGBREAK", signalCleanup);
  }
+
+  return {
+    unregister: () => {
+      for (const { event, listener } of handlers) {
+        process.off(event, listener);
+      }
+      handlers.length = 0;
+    },
+  };
 }
--- a/src/tools/lsp/lsp-server.ts
+++ b/src/tools/lsp/lsp-server.ts
@@ -1,73 +1,74 @@
-import type { ResolvedServer } from "./types"
-import { registerLspManagerProcessCleanup } from "./lsp-manager-process-cleanup"
-import { cleanupTempDirectoryLspClients } from "./lsp-manager-temp-directory-cleanup"
-import { LSPClient } from "./lsp-client"
+import { LSPClient } from "./lsp-client";
+import { registerLspManagerProcessCleanup, type LspProcessCleanupHandle } from "./lsp-manager-process-cleanup";
+import { cleanupTempDirectoryLspClients } from "./lsp-manager-temp-directory-cleanup";
+import type { ResolvedServer } from "./types";
 interface ManagedClient {
-  client: LSPClient
-  lastUsedAt: number
-  refCount: number
-  initPromise?: Promise<void>
-  isInitializing: boolean
-  initializingSince?: number
+  client: LSPClient;
+  lastUsedAt: number;
+  refCount: number;
+  initPromise?: Promise<void>;
+  isInitializing: boolean;
+  initializingSince?: number;
 }
 class LSPServerManager {
-  private static instance: LSPServerManager
-  private clients = new Map<string, ManagedClient>()
-  private cleanupInterval: ReturnType<typeof setInterval> | null = null
-  private readonly IDLE_TIMEOUT = 5 * 60 * 1000
-  private readonly INIT_TIMEOUT = 60 * 1000
+  private static instance: LSPServerManager;
+  private clients = new Map<string, ManagedClient>();
+  private cleanupInterval: ReturnType<typeof setInterval> | null = null;
+  private readonly IDLE_TIMEOUT = 5 * 60 * 1000;
+  private readonly INIT_TIMEOUT = 60 * 1000;
+  private cleanupHandle: LspProcessCleanupHandle | null = null;
  private constructor() {
-    this.startCleanupTimer()
-    this.registerProcessCleanup()
+    this.startCleanupTimer();
+    this.registerProcessCleanup();
  }
  private registerProcessCleanup(): void {
-    registerLspManagerProcessCleanup({
+    this.cleanupHandle = registerLspManagerProcessCleanup({
      getClients: () => this.clients.entries(),
      clearClients: () => {
-        this.clients.clear()
+        this.clients.clear();
      },
      clearCleanupInterval: () => {
        if (this.cleanupInterval) {
-          clearInterval(this.cleanupInterval)
-          this.cleanupInterval = null
+          clearInterval(this.cleanupInterval);
+          this.cleanupInterval = null;
        }
      },
-    })
+    });
  }

  static getInstance(): LSPServerManager {
    if (!LSPServerManager.instance) {
-      LSPServerManager.instance = new LSPServerManager()
+      LSPServerManager.instance = new LSPServerManager();
    }
-    return LSPServerManager.instance
+    return LSPServerManager.instance;
  }

  private getKey(root: string, serverId: string): string {
-    return `${root}::${serverId}`
+    return `${root}::${serverId}`;
  }

  private startCleanupTimer(): void {
-    if (this.cleanupInterval) return
+    if (this.cleanupInterval) return;
    this.cleanupInterval = setInterval(() => {
-      this.cleanupIdleClients()
-    }, 60000)
+      this.cleanupIdleClients();
+    }, 60000);
  }

  private cleanupIdleClients(): void {
-    const now = Date.now()
+    const now = Date.now();
    for (const [key, managed] of this.clients) {
      if (managed.refCount === 0 && now - managed.lastUsedAt > this.IDLE_TIMEOUT) {
-        managed.client.stop()
-        this.clients.delete(key)
+        managed.client.stop();
+        this.clients.delete(key);
      }
    }
  }

  async getClient(root: string, server: ResolvedServer): Promise<LSPClient> {
-    const key = this.getKey(root, server.id)
-    let managed = this.clients.get(key)
+    const key = this.getKey(root, server.id);
+    let managed = this.clients.get(key);
    if (managed) {
-      const now = Date.now()
+      const now = Date.now();
      if (
        managed.isInitializing &&
        managed.initializingSince !== undefined &&
@@ -75,45 +76,45 @@ class LSPServerManager {
      ) {
        // Stale init can permanently block subsequent calls (e.g., LSP process hang)
        try {
-          await managed.client.stop()
+          await managed.client.stop();
        } catch {}
-        this.clients.delete(key)
-        managed = undefined
+        this.clients.delete(key);
+        managed = undefined;
      }
    }
    if (managed) {
      if (managed.initPromise) {
        try {
-          await managed.initPromise
+          await managed.initPromise;
        } catch {
          // Failed init should not keep the key blocked forever.
          try {
-            await managed.client.stop()
+            await managed.client.stop();
          } catch {}
-          this.clients.delete(key)
-          managed = undefined
+          this.clients.delete(key);
+          managed = undefined;
        }
      }

      if (managed) {
        if (managed.client.isAlive()) {
-          managed.refCount++
-          managed.lastUsedAt = Date.now()
-          return managed.client
+          managed.refCount++;
+          managed.lastUsedAt = Date.now();
+          return managed.client;
        }
        try {
-          await managed.client.stop()
+          await managed.client.stop();
        } catch {}
-        this.clients.delete(key)
+        this.clients.delete(key);
      }
    }

-    const client = new LSPClient(root, server)
+    const client = new LSPClient(root, server);
    const initPromise = (async () => {
-      await client.start()
-      await client.initialize()
-    })()
-    const initStartedAt = Date.now()
+      await client.start();
+      await client.initialize();
+    })();
+    const initStartedAt = Date.now();
    this.clients.set(key, {
      client,
      lastUsedAt: initStartedAt,
@@ -121,37 +122,37 @@ class LSPServerManager {
      initPromise,
      isInitializing: true,
      initializingSince: initStartedAt,
-    })
+    });

    try {
-      await initPromise
+      await initPromise;
    } catch (error) {
-      this.clients.delete(key)
+      this.clients.delete(key);
      try {
-        await client.stop()
+        await client.stop();
      } catch {}
-      throw error
+      throw error;
    }
-    const m = this.clients.get(key)
+    const m = this.clients.get(key);
    if (m) {
-      m.initPromise = undefined
-      m.isInitializing = false
-      m.initializingSince = undefined
+      m.initPromise = undefined;
+      m.isInitializing = false;
+      m.initializingSince = undefined;
    }

-    return client
+    return client;
  }

  warmupClient(root: string, server: ResolvedServer): void {
-    const key = this.getKey(root, server.id)
-    if (this.clients.has(key)) return
-    const client = new LSPClient(root, server)
+    const key = this.getKey(root, server.id);
+    if (this.clients.has(key)) return;
+    const client = new LSPClient(root, server);
    const initPromise = (async () => {
-      await client.start()
-      await client.initialize()
-    })()
+      await client.start();
+      await client.initialize();
+    })();

-    const initStartedAt = Date.now()
+    const initStartedAt = Date.now();
    this.clients.set(key, {
      client,
      lastUsedAt: initStartedAt,
@@ -159,53 +160,55 @@ class LSPServerManager {
      initPromise,
      isInitializing: true,
      initializingSince: initStartedAt,
-    })
+    });

    initPromise
      .then(() => {
-        const m = this.clients.get(key)
+        const m = this.clients.get(key);
        if (m) {
-          m.initPromise = undefined
-          m.isInitializing = false
-          m.initializingSince = undefined
+          m.initPromise = undefined;
+          m.isInitializing = false;
+          m.initializingSince = undefined;
        }
      })
      .catch(() => {
        // Warmup failures must not permanently block future initialization.
-        this.clients.delete(key)
-        void client.stop().catch(() => {})
-      })
+        this.clients.delete(key);
+        void client.stop().catch(() => {});
+      });
  }

  releaseClient(root: string, serverId: string): void {
-    const key = this.getKey(root, serverId)
-    const managed = this.clients.get(key)
+    const key = this.getKey(root, serverId);
+    const managed = this.clients.get(key);
    if (managed && managed.refCount > 0) {
-      managed.refCount--
-      managed.lastUsedAt = Date.now()
+      managed.refCount--;
+      managed.lastUsedAt = Date.now();
    }
  }

  isServerInitializing(root: string, serverId: string): boolean {
-    const key = this.getKey(root, serverId)
-    const managed = this.clients.get(key)
-    return managed?.isInitializing ?? false
+    const key = this.getKey(root, serverId);
+    const managed = this.clients.get(key);
+    return managed?.isInitializing ?? false;
  }

  async stopAll(): Promise<void> {
+    this.cleanupHandle?.unregister();
+    this.cleanupHandle = null;
    for (const [, managed] of this.clients) {
-      await managed.client.stop()
+      await managed.client.stop();
    }
-    this.clients.clear()
+    this.clients.clear();
    if (this.cleanupInterval) {
-      clearInterval(this.cleanupInterval)
-      this.cleanupInterval = null
+      clearInterval(this.cleanupInterval);
+      this.cleanupInterval = null;
    }
  }

  async cleanupTempDirectoryClients(): Promise<void> {
-    await cleanupTempDirectoryLspClients(this.clients)
+    await cleanupTempDirectoryLspClients(this.clients);
  }
 }

-export const lspManager = LSPServerManager.getInstance()
+export const lspManager = LSPServerManager.getInstance();
Author	SHA1	Message	Date
Cole Leavitt	f92d2e8f7f	fix: add proc.kill fallback when process group kill fails	2026-02-22 15:06:09 +09:00
Cole Leavitt	7f0950230c	fix: kill process group on timeout and handle stdin EPIPE - Use detached process group (non-Windows) + process.kill(-pid) to kill the entire process tree, not just the outer shell wrapper - Add proc.stdin error listener to absorb EPIPE when child exits before stdin write completes	2026-02-22 15:06:09 +09:00
Cole Leavitt	e1568a4705	fix: handle signal-killed exit code and guard SIGTERM kill - code ?? 0 → code ?? 1: signal-terminated processes return null exit code, which was incorrectly coerced to 0 (success) instead of 1 (failure) - wrap proc.kill(SIGTERM) in try/catch to match SIGKILL guard and prevent EPERM/ESRCH from crashing on already-dead processes	2026-02-22 15:06:09 +09:00
Cole Leavitt	b666ab24df	fix: plug resource leaks and add hook command timeout - LSP signal handlers: store refs, return unregister handle, call in stopAll() - session-tools-store: add per-session deleteSessionTools(), wire into session.deleted - executeHookCommand: add 30s timeout with SIGTERM→SIGKILL escalation	2026-02-22 15:06:09 +09:00
YeonGyu-Kim	ac81e1d7cd	fix(hashline-edit): correct offset advancement and fuzzy index mapping in merge expand - Track matchedLen separately for stripped continuation token matches - Map fuzzy index back to original string position via character-by-character scan that skips operator chars, fixing positional correctness	2026-02-22 14:50:59 +09:00
YeonGyu-Kim	9390f98f01	fix(hashline-edit): integrate continuation/merge helpers into expand logic and strengthen tool description - maybeExpandSingleLineMerge now uses stripTrailingContinuationTokens and stripMergeOperatorChars as fallback matching strategies - Add 'refs interpreted against last read' atomicity clause to tool description - Add 'output tool calls only; no prose' rule to tool description	2026-02-22 14:46:59 +09:00
YeonGyu-Kim	e6868e9112	fix(hashline-edit): align autocorrect, BOM/CRLF, and tool description with oh-my-pi - Rewrite restoreOldWrappedLines to use oh-my-pi's span-scanning algorithm - Add stripTrailingContinuationTokens and stripMergeOperatorChars helpers - Fix detectLineEnding to use first-occurrence logic instead of any-match - Fix applyAppend/applyPrepend to replace empty-line placeholder in empty files - Enhance tool description with 7 critical rules, tag guidance, and anti-patterns	2026-02-22 14:40:18 +09:00
YeonGyu-Kim	5d1d87cc10	feat(hashline-edit): add autocorrect, BOM/CRLF normalization, and file creation support Implements key features from oh-my-pi to improve agent editing success rates: - Autocorrect v1: single-line merge expansion, wrapped line restoration, paired indent restoration (autocorrect-replacement-lines.ts) - BOM/CRLF normalization: canonicalize on read, restore on write (file-text-canonicalization.ts) - Pre-validate all hashes before mutation (edit-ordering.ts) - File creation via append/prepend operations (new types + executor logic) - Modular refactoring: split edit-operations.ts into focused modules (primitives, ordering, deduplication, diff, executor) - Enhanced tool description with operation choice guide and recovery hints All 50 tests pass. TypeScript clean. Build successful.	2026-02-22 14:13:59 +09:00