refactor(hooks): replace direct output.args mutation with replaceToolArgs (question/webfetch/null-byte)

Replace Object.assign(output.args, truncatedArgs), output.args.url = resolution.url,
and output.args.command = ... .replace(/\x00/g, "") with replaceToolArgs() calls
in question-label-truncator, webfetch-redirect-guard, and plugin/tool-execute-before.

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

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

src/hooks/question-label-truncator/hook.ts

@@ -1,3 +1,5 @@
+import { replaceToolArgs } from "../../shared/replace-tool-args"
+
 const MAX_LABEL_LENGTH = 30;
 
 interface QuestionOption {
@@ -56,7 +58,7 @@ export function createQuestionLabelTruncatorHook() {
       if (toolName === "askuserquestion" || toolName === "ask_user_question") {
         if (hasQuestions(output.args)) {
           const truncatedArgs = truncateQuestionLabels(output.args);
-          Object.assign(output.args, truncatedArgs);
+          replaceToolArgs(output, { questions: truncatedArgs.questions });
         }
       }
     },

src/hooks/webfetch-redirect-guard/hook.ts

@@ -1,5 +1,5 @@
 import type { PluginInput } from "@opencode-ai/plugin"
-import { log } from "../../shared"
+import { log, replaceToolArgs } from "../../shared"
 import {
   MAX_WEBFETCH_REDIRECTS,
   WEBFETCH_REDIRECT_ERROR_PATTERNS,
@@ -85,7 +85,7 @@ export function createWebFetchRedirectGuardHook(_ctx: PluginInput) {
         })
 
         if (resolution.type === "resolved") {
-          output.args.url = resolution.url
+          replaceToolArgs(output, { url: resolution.url })
           return
         }
 

src/plugin/tool-execute-before.ts

@@ -3,7 +3,7 @@ import { randomUUID } from "node:crypto"
 
 import { getMainSessionID } from "../features/claude-code-session-state"
 import { clearBoulderState } from "../features/boulder-state"
-import { log } from "../shared"
+import { log, replaceToolArgs } from "../shared"
 import { stripInvisibleAgentCharacters } from "../shared/agent-display-names"
 import { resolveSessionAgent } from "./session-agent-resolver"
 import { parseRalphLoopArguments } from "../hooks/ralph-loop/command-arguments"
@@ -54,7 +54,7 @@ export function createToolExecuteBeforeHandler(args: {
   return async (input, output): Promise<void> => {
     if (input.tool.toLowerCase() === "bash" && typeof output.args.command === "string") {
       if (output.args.command.includes("\x00")) {
-        output.args.command = output.args.command.replace(/\x00/g, "")
+        replaceToolArgs(output, { command: output.args.command.replace(/\x00/g, "") })
         log("[tool-execute-before] Stripped null bytes from bash command", {
           sessionID: input.sessionID,
           callID: input.callID,