refactor(tools): narrow optional values

Avoid non-null assertions in tool and doctor code by preserving narrowed locals through each use site.

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

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

src/cli/doctor/checks/dependencies.ts

@@ -6,7 +6,11 @@ import type { DependencyInfo } from "../types"
 import { spawnWithTimeout } from "../spawn-with-timeout"
 import { getCachedBinaryPath } from "../../../hooks/comment-checker/downloader"
 
-async function checkBinaryExists(binary: string): Promise<{ exists: boolean; path: string | null }> {
+type BinaryCheck =
+  | { exists: true; path: string }
+  | { exists: false; path: null }
+
+async function checkBinaryExists(binary: string): Promise<BinaryCheck> {
   try {
     const path = Bun.which(binary)
     if (path) {
@@ -44,7 +48,7 @@ export async function checkAstGrepCli(): Promise<DependencyInfo> {
     }
   }
 
-  const version = await getBinaryVersion(binary.path!)
+  const version = await getBinaryVersion(binary.path)
 
   return {
     name: "AST-Grep CLI",

src/tools/background-task/create-background-cancel.ts

@@ -15,10 +15,6 @@ export function createBackgroundCancel(manager: BackgroundManager, _client: Back
       try {
         const cancelAll = args.all === true
 
-        if (!cancelAll && !args.taskId) {
-          return `[ERROR] Invalid arguments: Either provide a taskId or set all=true to cancel all running tasks.`
-        }
-
         if (cancelAll) {
           const tasks = manager.getAllDescendantTasks(toolContext.sessionID)
           const cancellableTasks = tasks.filter((t: { status: string }) => t.status === "running" || t.status === "pending")
@@ -74,9 +70,14 @@ ${tableRows}
 ${resumeSection}`
         }
 
-        const task = manager.getTask(args.taskId!)
+        const taskId = args.taskId
+        if (!taskId) {
+          return `[ERROR] Invalid arguments: Either provide a taskId or set all=true to cancel all running tasks.`
+        }
+
+        const task = manager.getTask(taskId)
         if (!task) {
-          return `[ERROR] Task not found: ${args.taskId}`
+          return `[ERROR] Task not found: ${taskId}`
         }
 
         if (task.status !== "running" && task.status !== "pending") {

src/tools/look-at/look-at-arguments.ts

@@ -13,10 +13,11 @@ export function normalizeArgs(args: LookAtArgsWithAlias): LookAtArgs {
 }
 
 export function validateArgs(args: LookAtArgs): string | null {
-  const hasFilePath = Boolean(args.file_path && args.file_path.length > 0)
+  const filePath = args.file_path
+  const hasFilePath = Boolean(filePath && filePath.length > 0)
   const hasImageData = Boolean(args.image_data && args.image_data.length > 0)
 
-  if (hasFilePath && /^https?:\/\//i.test(args.file_path!)) {
+  if (filePath && /^https?:\/\//i.test(filePath)) {
     return "Error: Remote URLs are not supported for file_path. Download the file first or use a local path."
   }
   if (!hasFilePath && !hasImageData) {

src/tools/lsp/lsp-client-transport.ts

@@ -136,22 +136,27 @@ export class LSPClientTransport {
       throw new Error(`LSP server already exited (code: ${this.proc?.exitCode})` + (stderr ? `\nstderr: ${stderr}` : ""))
     }
 
-    let timeoutId: ReturnType<typeof setTimeout>
+    let timeoutId: ReturnType<typeof setTimeout> | undefined
     const timeoutPromise = new Promise<never>((_, reject) => {
       timeoutId = setTimeout(() => {
         const stderr = this.stderrBuffer.slice(-5).join("\n")
         reject(new Error(`LSP request timeout (method: ${method})` + (stderr ? `\nrecent stderr: ${stderr}` : "")))
       }, this.REQUEST_TIMEOUT)
     })
+    const clearRequestTimeout = (): void => {
+      if (timeoutId !== undefined) {
+        clearTimeout(timeoutId)
+      }
+    }
 
     const requestPromise = this.connection.sendRequest(method, ...args) as Promise<T>
 
     try {
       const result = await Promise.race([requestPromise, timeoutPromise])
-      clearTimeout(timeoutId!)
+      clearRequestTimeout()
       return result
     } catch (error) {
-      clearTimeout(timeoutId!)
+      clearRequestTimeout()
       throw error
     }
   }

src/tools/lsp/symbols-tool.ts

@@ -22,12 +22,13 @@ export const lsp_symbols: ToolDefinition = tool({
       const scope = args.scope ?? "document"
 
       if (scope === "workspace") {
-        if (!args.query) {
+        const query = args.query
+        if (!query) {
           return "Error: 'query' is required for workspace scope"
         }
 
         const result = await withLspClient(args.filePath, async (client) => {
-          return (await client.workspaceSymbols(args.query!)) as SymbolInfo[] | null
+          return (await client.workspaceSymbols(query)) as SymbolInfo[] | null
         })
 
         if (!result || result.length === 0) {