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fix: properly type-check Bash tool input without type assertion #28

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Merged
johnlindquist merged 2 commits into from
Jul 8, 2025
Merged

fix: properly type-check Bash tool input without type assertion #28

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fix: properly type-check Bash tool input without type assertion
johnlindquist Jul 8, 2025
d999623
Merge branch 'main' into fix-typescript-error-in-hooks-template
johnlindquist Jul 8, 2025
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4 changes: 1 addition & 3 deletions templates/hooks/index.ts
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Original file line number Diff line number Diff line change
@@ -1,7 +1,6 @@
#!/usr/bin/env bun

import {
type BashToolInput,
type NotificationPayload,
type PostToolUsePayload,
type PreToolUsePayload,
Expand All @@ -25,8 +24,7 @@ async function preToolUse(payload: PreToolUsePayload): Promise<PreToolUseRespons

// Example: Track bash commands
if (payload.tool_name === 'Bash' && payload.tool_input && 'command' in payload.tool_input) {
const bashInput = payload.tool_input as BashToolInput
const command = bashInput.command
const command = (payload.tool_input as {command: string}).command
console.log(`🚀 Running command: ${command}`)
Comment on lines 26 to 28
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@coderabbitai coderabbitai bot Jul 8, 2025

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🛠️ Refactor suggestion

Prefer a type-guard to eliminate the unsafe cast

The direct assertion (payload.tool_input as {command: string}).command silently trusts the payload’s shape. A tiny, locally-scoped type-guard keeps the compiler on your side and avoids re-introducing the deprecated double-assertion pattern:

-type BashToolInput = {command: string}
-function isBashToolInput(input: unknown): input is BashToolInput {
-  return !!input && typeof (input as any).command === 'string'
-}
-
-if (payload.tool_name === 'Bash' && isBashToolInput(payload.tool_input)) {
-  const {command} = payload.tool_input
+type BashToolInput = {command: string}
+function isBashToolInput(input: unknown): input is BashToolInput {
+  return !!input && typeof (input as any).command === 'string'
+}
+
+if (payload.tool_name === 'Bash' && isBashToolInput(payload.tool_input)) {
+  const {command} = payload.tool_input
   console.log(`🚀 Running command: ${command}`)

This keeps the file self-contained (no additional import) while giving the compiler a real guard instead of a blind cast.

Committable suggestion skipped: line range outside the PR's diff.

🤖 Prompt for AI Agents 
In templates/hooks/index.ts around lines 26 to 28, replace the direct type
assertion of payload.tool_input with a locally defined type-guard function that
checks if tool_input has a command property of type string. Use this type-guard
to safely access the command property without casting, ensuring type safety and
avoiding deprecated double-assertion patterns.


// Block dangerous commands
Expand Down