diff --git a/packages/cli/src/ui/hooks/toolMapping.ts b/packages/cli/src/ui/hooks/toolMapping.ts
index afb8b34755..0ee950c6bf 100644
--- a/packages/cli/src/ui/hooks/toolMapping.ts
+++ b/packages/cli/src/ui/hooks/toolMapping.ts
@@ -42,10 +42,9 @@ export function mapToDisplay(
     if (call.status === CoreToolCallStatus.Error) {
       description = JSON.stringify(call.request.args);
     } else {
-      description =
-        typeof call.invocation.getDisplayTitle === 'function'
-          ? call.invocation.getDisplayTitle()
-          : call.invocation.getDescription();
+      description = call.invocation.getDisplayTitle
+        ? call.invocation.getDisplayTitle()
+        : call.invocation.getDescription();
       renderOutputAsMarkdown = call.tool.isOutputMarkdown;
     }
 
diff --git a/packages/core/src/agents/local-executor.ts b/packages/core/src/agents/local-executor.ts
index b62df0d11b..3f1acad836 100644
--- a/packages/core/src/agents/local-executor.ts
+++ b/packages/core/src/agents/local-executor.ts
@@ -1026,10 +1026,9 @@ export class LocalAgentExecutor<TOutput extends z.ZodTypeAny> {
           const invocation = tool.build(args);
           // Prefer getDisplayTitle if it differs, otherwise fallback to getDescription.
           // This ensures the timeline ("Shell (Replace)") matches the confirmation dialog.
-          description =
-            typeof invocation.getDisplayTitle === 'function'
-              ? invocation.getDisplayTitle()
-              : invocation.getDescription();
+          description = invocation.getDisplayTitle
+            ? invocation.getDisplayTitle()
+            : invocation.getDescription();
         }
       } catch {
         // Ignore errors during formatting for activity emission
diff --git a/packages/core/src/core/geminiChat.ts b/packages/core/src/core/geminiChat.ts
index 3fb966ecf0..312622d481 100644
--- a/packages/core/src/core/geminiChat.ts
+++ b/packages/core/src/core/geminiChat.ts
@@ -30,9 +30,12 @@ import {
   isGemini2Model,
   supportsModernFeatures,
 } from '../config/models.js';
-import { hasCycleInSchema } from '../tools/tools.js';
+import { hasCycleInSchema, hasDisplayTitle } from '../tools/tools.js';
 import type { StructuredError } from './turn.js';
-import type { CompletedToolCall } from '../scheduler/types.js';
+import {
+  type CompletedToolCall,
+  isInvocationCall,
+} from '../scheduler/types.js';
 import {
   logContentRetry,
   logContentRetryFailure,
@@ -1031,11 +1034,10 @@ export class GeminiChat {
           : undefined;
 
       let description: string | undefined = undefined;
-      if ('invocation' in call && call.invocation) {
-        description =
-          typeof call.invocation.getDisplayTitle === 'function'
-            ? call.invocation.getDisplayTitle()
-            : call.invocation.getDescription();
+      if (isInvocationCall(call)) {
+        description = hasDisplayTitle(call.invocation)
+          ? call.invocation.getDisplayTitle()
+          : call.invocation.getDescription();
       }
 
       return {
diff --git a/packages/core/src/scheduler/types.ts b/packages/core/src/scheduler/types.ts
index 170aab67ca..073d98bef9 100644
--- a/packages/core/src/scheduler/types.ts
+++ b/packages/core/src/scheduler/types.ts
@@ -5,13 +5,14 @@
  */
 
 import type { Part } from '@google/genai';
-import type {
-  AnyDeclarativeTool,
-  AnyToolInvocation,
-  ToolCallConfirmationDetails,
-  ToolConfirmationOutcome,
-  ToolResultDisplay,
-  ToolLiveOutput,
+import {
+  isAnyToolInvocation,
+  type AnyDeclarativeTool,
+  type AnyToolInvocation,
+  type ToolCallConfirmationDetails,
+  type ToolConfirmationOutcome,
+  type ToolResultDisplay,
+  type ToolLiveOutput,
 } from '../tools/tools.js';
 import type { ToolErrorType } from '../tools/tool-error.js';
 import type { SerializableConfirmationDetails } from '../confirmation-bus/types.js';
@@ -195,6 +196,12 @@ export type CompletedToolCall =
   | CancelledToolCall
   | ErroredToolCall;
 
+export function isInvocationCall(
+  call: CompletedToolCall,
+): call is CompletedToolCall & { invocation: AnyToolInvocation } {
+  return 'invocation' in call && isAnyToolInvocation(call.invocation);
+}
+
 export type ConfirmHandler = (
   toolCall: WaitingToolCall,
 ) => Promise<ToolConfirmationOutcome>;
diff --git a/packages/core/src/tools/shell.test.ts b/packages/core/src/tools/shell.test.ts
index a19520f0e1..231a1eef59 100644
--- a/packages/core/src/tools/shell.test.ts
+++ b/packages/core/src/tools/shell.test.ts
@@ -139,6 +139,7 @@ describe('ShellTool', () => {
       getShellBackgroundCompletionBehavior: vi.fn().mockReturnValue('silent'),
       getEnableShellOutputEfficiency: vi.fn().mockReturnValue(true),
       getSandboxEnabled: vi.fn().mockReturnValue(false),
+      getUsageStatisticsEnabled: vi.fn().mockReturnValue(false),
       sanitizationConfig: {},
       sandboxManager: new NoopSandboxManager(),
     } as unknown as Config;
diff --git a/packages/core/src/tools/shell.ts b/packages/core/src/tools/shell.ts
index 29ec9fb9ba..fddb1e57a9 100644
--- a/packages/core/src/tools/shell.ts
+++ b/packages/core/src/tools/shell.ts
@@ -44,7 +44,6 @@ import {
   parseCommandDetails,
   hasRedirection,
   inferFileOperation,
-  FileOperationType,
 } from '../utils/shell-utils.js';
 import { logFileOperation } from '../telemetry/loggers.js';
 import { FileOperationEvent } from '../telemetry/types.js';
@@ -143,13 +142,13 @@ export class ShellToolInvocation extends BaseToolInvocation<
     const inferred = inferFileOperation(this.params.command);
     if (inferred) {
       switch (inferred.type) {
-        case FileOperationType.SEARCH:
+        case 'search':
           return `Shell (Search)`;
-        case FileOperationType.EDIT:
+        case 'edit':
           return `Shell (Replace)`;
-        case FileOperationType.WRITE:
+        case 'write':
           return `Shell (Write File)`;
-        case FileOperationType.READ:
+        case 'read':
           return `Shell (Read File)`;
         default:
           break;
@@ -225,11 +224,7 @@ export class ShellToolInvocation extends BaseToolInvocation<
     const command = stripShellWrapper(this.params.command);
     const inferred = inferFileOperation(this.params.command);
 
-    if (
-      inferred &&
-      (inferred.type === FileOperationType.EDIT ||
-        inferred.type === FileOperationType.WRITE)
-    ) {
+    if (inferred && (inferred.type === 'edit' || inferred.type === 'write')) {
       const filePath = path.resolve(
         this.context.config.getTargetDir(),
         inferred.filePath,
@@ -242,23 +237,24 @@ export class ShellToolInvocation extends BaseToolInvocation<
       }
 
       let newContent: string | undefined;
-      if (
-        inferred.type === FileOperationType.EDIT &&
-        originalContent !== null
-      ) {
-        if (typeof inferred.metadata?.['sedExpression'] === 'string') {
+      if (inferred.type === 'edit' && originalContent !== null) {
+        if (
+          inferred.metadata?.type === 'edit' &&
+          inferred.metadata.sedExpression
+        ) {
           newContent = this.simulateSed(
             originalContent,
-            inferred.metadata['sedExpression'],
+            inferred.metadata.sedExpression,
           );
         } else if (
-          typeof inferred.metadata?.['oldString'] === 'string' &&
-          typeof inferred.metadata?.['newString'] === 'string'
+          inferred.metadata?.type === 'edit' &&
+          inferred.metadata.oldString &&
+          inferred.metadata.newString
         ) {
           newContent = this.simulatePsReplace(
             originalContent,
-            inferred.metadata['oldString'],
-            inferred.metadata['newString'],
+            inferred.metadata.oldString,
+            inferred.metadata.newString,
           );
         }
       }
@@ -501,19 +497,19 @@ export class ShellToolInvocation extends BaseToolInvocation<
         let operation: FileOperation | undefined;
         let canonicalToolName = SHELL_TOOL_NAME;
         switch (inferred.type) {
-          case FileOperationType.SEARCH:
+          case 'search':
             operation = FileOperation.READ;
             canonicalToolName = GREP_TOOL_NAME;
             break;
-          case FileOperationType.READ:
+          case 'read':
             operation = FileOperation.READ;
             canonicalToolName = READ_FILE_TOOL_NAME;
             break;
-          case FileOperationType.EDIT:
+          case 'edit':
             operation = FileOperation.UPDATE;
             canonicalToolName = EDIT_TOOL_NAME;
             break;
-          case FileOperationType.WRITE:
+          case 'write':
             operation = FileOperation.UPDATE;
             canonicalToolName = WRITE_FILE_TOOL_NAME;
             break;
diff --git a/packages/core/src/tools/tools.ts b/packages/core/src/tools/tools.ts
index 23e88b608b..072a9c951f 100644
--- a/packages/core/src/tools/tools.ts
+++ b/packages/core/src/tools/tools.ts
@@ -392,6 +392,32 @@ export abstract class BaseToolInvocation<
  */
 export type AnyToolInvocation = ToolInvocation<object, ToolResult>;
 
+/**
+ * Type guard to check if an object is an AnyToolInvocation.
+ */
+export function isAnyToolInvocation(
+  invocation: unknown,
+): invocation is AnyToolInvocation {
+  if (typeof invocation !== 'object' || invocation === null) {
+    return false;
+  }
+
+  return (
+    'execute' in invocation &&
+    typeof invocation.execute === 'function' &&
+    'getDescription' in invocation &&
+    typeof invocation.getDescription === 'function' &&
+    'params' in invocation &&
+    isRecord(invocation.params)
+  );
+}
+
+export function hasDisplayTitle(
+  invocation: AnyToolInvocation,
+): invocation is AnyToolInvocation & { getDisplayTitle(): string } {
+  return typeof invocation.getDisplayTitle === 'function';
+}
+
 /**
  * Interface for a tool builder that validates parameters and creates invocations.
  */
diff --git a/packages/core/src/utils/shell-utils.test.ts b/packages/core/src/utils/shell-utils.test.ts
index 6c4c6c381d..e628e6a932 100644
--- a/packages/core/src/utils/shell-utils.test.ts
+++ b/packages/core/src/utils/shell-utils.test.ts
@@ -24,7 +24,6 @@ import {
   hasRedirection,
   resolveExecutable,
   inferFileOperation,
-  FileOperationType,
 } from './shell-utils.js';
 import path from 'node:path';
 
@@ -611,16 +610,19 @@ describe('inferFileOperation', () => {
     mockPlatform.mockReturnValue('linux');
     const result = inferFileOperation("sed -i 's/foo/bar/g' test.ts");
     expect(result).toBeDefined();
-    expect(result?.type).toBe(FileOperationType.EDIT);
+    expect(result?.type).toBe('edit');
     expect(result?.filePath).toBe('test.ts');
-    expect(result?.metadata?.['sedExpression']).toBe('s/foo/bar/g');
+    expect(result?.metadata?.type).toBe('edit');
+    if (result?.metadata?.type === 'edit') {
+      expect(result.metadata.sedExpression).toBe('s/foo/bar/g');
+    }
   });
 
   it('should infer echo redirection as a WRITE operation', () => {
     mockPlatform.mockReturnValue('linux');
     const result = inferFileOperation("echo 'hello' > hello.txt");
     expect(result).toBeDefined();
-    expect(result?.type).toBe(FileOperationType.WRITE);
+    expect(result?.type).toBe('write');
     expect(result?.filePath).toBe('hello.txt');
   });
 
@@ -628,9 +630,12 @@ describe('inferFileOperation', () => {
     mockPlatform.mockReturnValue('linux');
     const result = inferFileOperation("grep 'pattern' file.txt");
     expect(result).toBeDefined();
-    expect(result?.type).toBe(FileOperationType.SEARCH);
+    expect(result?.type).toBe('search');
     expect(result?.filePath).toBe('file.txt');
-    expect(result?.metadata?.['pattern']).toBe('pattern');
+    expect(result?.metadata?.type).toBe('search');
+    if (result?.metadata?.type === 'search') {
+      expect(result.metadata.pattern).toBe('pattern');
+    }
   });
 
   it('should infer PowerShell -replace as an EDIT operation', () => {
@@ -639,9 +644,12 @@ describe('inferFileOperation', () => {
       "(Get-Content file.txt) -replace 'a', 'b' | Set-Content file.txt",
     );
     expect(result).toBeDefined();
-    expect(result?.type).toBe(FileOperationType.EDIT);
+    expect(result?.type).toBe('edit');
     expect(result?.filePath).toBe('file.txt');
-    expect(result?.metadata?.['oldString']).toBe('a');
-    expect(result?.metadata?.['newString']).toBe('b');
+    expect(result?.metadata?.type).toBe('edit');
+    if (result?.metadata?.type === 'edit') {
+      expect(result.metadata.oldString).toBe('a');
+      expect(result.metadata.newString).toBe('b');
+    }
   });
 });
diff --git a/packages/core/src/utils/shell-utils.ts b/packages/core/src/utils/shell-utils.ts
index 466a98b7e0..b1a5ec806b 100644
--- a/packages/core/src/utils/shell-utils.ts
+++ b/packages/core/src/utils/shell-utils.ts
@@ -623,18 +623,39 @@ export function getShellConfiguration(): ShellConfiguration {
  */
 export const isWindows = () => os.platform() === 'win32';
 
-export enum FileOperationType {
-  SEARCH = 'SEARCH',
-  EDIT = 'EDIT',
-  WRITE = 'WRITE',
-  READ = 'READ',
-}
+export type FileOperationType = 'search' | 'edit' | 'write' | 'read';
+
+export type SearchFileMetadata = {
+  type: 'search';
+  pattern: string;
+};
+
+export type EditFileMetadata = {
+  type: 'edit';
+  sedExpression?: string;
+  oldString?: string;
+  newString?: string;
+};
+
+export type WriteFileMetadata = {
+  type: 'write';
+};
+
+export type ReadFileMetadata = {
+  type: 'read';
+};
+
+export type InferredFileMetadata =
+  | SearchFileMetadata
+  | EditFileMetadata
+  | WriteFileMetadata
+  | ReadFileMetadata;
 
 export interface InferredFileOperation {
   type: FileOperationType;
   filePath: string;
   /** Inferred details (e.g., the sed expression or replacement string) */
-  metadata?: Record<string, unknown>;
+  metadata?: InferredFileMetadata;
 }
 
 /**
@@ -783,9 +804,9 @@ export function inferFileOperation(
     );
     if (sedMatch) {
       return {
-        type: FileOperationType.EDIT,
+        type: 'edit',
         filePath: sedMatch[2].trim(),
-        metadata: { sedExpression: sedMatch[1] },
+        metadata: { type: 'edit', sedExpression: sedMatch[1] },
       };
     }
 
@@ -796,7 +817,7 @@ export function inferFileOperation(
     );
     if (redirectionMatch) {
       return {
-        type: FileOperationType.WRITE,
+        type: 'write',
         filePath: redirectionMatch[1].trim(),
       };
     }
@@ -807,7 +828,7 @@ export function inferFileOperation(
     );
     if (heredocMatch) {
       return {
-        type: FileOperationType.WRITE,
+        type: 'write',
         filePath: heredocMatch[1].trim(),
       };
     }
@@ -818,7 +839,7 @@ export function inferFileOperation(
     );
     if (cpMatch) {
       return {
-        type: FileOperationType.WRITE,
+        type: 'write',
         filePath: cpMatch[2].trim(),
       };
     }
@@ -829,7 +850,7 @@ export function inferFileOperation(
     );
     if (mvMatch) {
       return {
-        type: FileOperationType.WRITE,
+        type: 'write',
         filePath: mvMatch[2].trim(),
       };
     }
@@ -840,7 +861,7 @@ export function inferFileOperation(
     );
     if (teeMatch) {
       return {
-        type: FileOperationType.WRITE,
+        type: 'write',
         filePath: teeMatch[1].trim(),
       };
     }
@@ -851,9 +872,9 @@ export function inferFileOperation(
     );
     if (grepMatch) {
       return {
-        type: FileOperationType.SEARCH,
+        type: 'search',
         filePath: grepMatch[2].trim(),
-        metadata: { pattern: grepMatch[1] },
+        metadata: { type: 'search', pattern: grepMatch[1] },
       };
     }
 
@@ -863,7 +884,7 @@ export function inferFileOperation(
     );
     if (readMatch) {
       return {
-        type: FileOperationType.READ,
+        type: 'read',
         filePath: readMatch[1].trim(),
       };
     }
@@ -874,9 +895,10 @@ export function inferFileOperation(
     );
     if (psReplaceMatch) {
       return {
-        type: FileOperationType.EDIT,
+        type: 'edit',
         filePath: psReplaceMatch[1].trim(),
         metadata: {
+          type: 'edit',
           oldString: psReplaceMatch[2],
           newString: psReplaceMatch[3],
         },
@@ -889,7 +911,7 @@ export function inferFileOperation(
     );
     if (psSetContentMatch) {
       return {
-        type: FileOperationType.WRITE,
+        type: 'write',
         filePath: psSetContentMatch[1].trim(),
       };
     }
@@ -900,9 +922,9 @@ export function inferFileOperation(
     );
     if (psSearchMatch) {
       return {
-        type: FileOperationType.SEARCH,
+        type: 'search',
         filePath: psSearchMatch[1].trim(),
-        metadata: { pattern: psSearchMatch[2] },
+        metadata: { type: 'search', pattern: psSearchMatch[2] },
       };
     }
 
@@ -912,7 +934,7 @@ export function inferFileOperation(
     );
     if (psReadMatch) {
       return {
-        type: FileOperationType.READ,
+        type: 'read',
         filePath: psReadMatch[1].trim(),
       };
     }