fix(security-review): Handle null shell output (#231)

Normalize shell command stdout and stderr before the prompt-shell path and shared tool-result mappers use string operations. This prevents /security-review from crashing when a shell tool returns null output fields and adds regression coverage for both direct mapper calls and prompt generation.

Fixes #165

Co-authored-by: Claude <noreply@anthropic.com>

src/utils/promptShellExecution.test.ts

@@ -0,0 +1,77 @@
+import { afterEach, expect, test } from 'bun:test'
+import { getEmptyToolPermissionContext } from '../Tool.js'
+import { BashTool } from '../tools/BashTool/BashTool.js'
+import { executeShellCommandsInPrompt } from './promptShellExecution.js'
+
+const originalCall = BashTool.call
+const originalMapToolResultToToolResultBlockParam =
+  BashTool.mapToolResultToToolResultBlockParam
+
+afterEach(() => {
+  BashTool.call = originalCall
+  BashTool.mapToolResultToToolResultBlockParam =
+    originalMapToolResultToToolResultBlockParam
+})
+
+test('executeShellCommandsInPrompt normalizes null shell output', async () => {
+  let normalizedResult:
+    | { stdout: string; stderr: string; interrupted: boolean }
+    | undefined
+
+  BashTool.call = (async () => ({
+    data: {
+      stdout: null,
+      stderr: null,
+      interrupted: false,
+    },
+  })) as unknown as typeof BashTool.call
+
+  BashTool.mapToolResultToToolResultBlockParam = (result, toolUseID) => {
+    normalizedResult = result as {
+      stdout: string
+      stderr: string
+      interrupted: boolean
+    }
+    return originalMapToolResultToToolResultBlockParam(result, toolUseID)
+  }
+
+  await executeShellCommandsInPrompt(
+    '```!\ngit status\n```',
+    {
+      abortController: new AbortController(),
+      options: {
+        commands: [],
+        debug: false,
+        mainLoopModel: 'sonnet',
+        tools: new Map(),
+        verbose: false,
+        thinkingConfig: { type: 'disabled' },
+        mcpClients: [],
+        mcpResources: {},
+        isNonInteractiveSession: false,
+        agentDefinitions: {
+          systemDefinitions: [],
+          projectDefinitions: [],
+          userDefinitions: [],
+        },
+      },
+      readFileState: new Map(),
+      getAppState() {
+        return {
+          toolPermissionContext: {
+            ...getEmptyToolPermissionContext(),
+            alwaysAllowRules: { command: ['Bash(*)'] },
+          },
+        }
+      },
+      setAppState() {},
+    } as never,
+    'security-review',
+  )
+
+  expect(normalizedResult).toEqual({
+    stdout: '',
+    stderr: '',
+    interrupted: false,
+  })
+})