diff --git a/AGENTS.md b/AGENTS.md
index 0243a082a..92afc67cb 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -148,6 +148,38 @@ See `docs/TESTING.md` for details.
 
 New features must include telemetry instrumentation. See `src/cli/telemetry/README.md` for how to add metrics.
 
+## Error Types
+
+Custom error types are encouraged — each distinct error class appears as its own category in telemetry, giving more
+granular failure data. All errors live in `src/lib/errors/types.ts`.
+
+To add a new error:
+
+1. Define a class in `src/lib/errors/types.ts` extending `BaseError` with a default `errorSource`:
+   - `'user'` — user-fixable (bad input, missing credentials, invalid config)
+   - `'client'` — our bug or unexpected local failure
+   - `'service'` — remote service issue (timeout, connection failure, server error)
+   - `'unknown'` — source cannot be determined
+
+```ts
+export class MyNewError extends BaseError {
+  constructor(message: string, options?: BaseErrorOptions) {
+    super(message, { defaultSource: 'user', ...options });
+  }
+}
+```
+
+Callers can override the source per throw site:
+
+```ts
+throw new MyNewError('not found', { errorSource: 'service', cause: originalErr });
+```
+
+2. Add `'MyNewError'` to the `ErrorName` enum in `src/cli/telemetry/schemas/common-shapes.ts`.
+
+That's it. The telemetry client reads `errorSource` and `name` directly from `BaseError` instances — no classification
+logic to update.
+
 ## Multi-Partition Support (GovCloud, China)
 
 The CLI supports multiple AWS partitions (commercial, GovCloud, China) through a central utility at
diff --git a/src/cli/aws/__tests__/account-extended.test.ts b/src/cli/aws/__tests__/account-extended.test.ts
index 2cf3dd085..c859634a8 100644
--- a/src/cli/aws/__tests__/account-extended.test.ts
+++ b/src/cli/aws/__tests__/account-extended.test.ts
@@ -1,4 +1,5 @@
-import { AwsCredentialsError, detectAccount, getCredentialProvider, validateAwsCredentials } from '../account.js';
+import { AwsCredentialsError } from '../../../lib/errors/types.js';
+import { detectAccount, getCredentialProvider, validateAwsCredentials } from '../account.js';
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 
 const { mockSend } = vi.hoisted(() => ({
diff --git a/src/cli/aws/__tests__/account.test.ts b/src/cli/aws/__tests__/account.test.ts
index 2c7c56cbc..e74a3eaf9 100644
--- a/src/cli/aws/__tests__/account.test.ts
+++ b/src/cli/aws/__tests__/account.test.ts
@@ -1,4 +1,4 @@
-import { AwsCredentialsError } from '../account.js';
+import { AwsCredentialsError } from '../../../lib/errors/types.js';
 import { describe, expect, it } from 'vitest';
 
 describe('AwsCredentialsError', () => {
diff --git a/src/cli/aws/account.ts b/src/cli/aws/account.ts
index 705d25cec..8e962cfb3 100644
--- a/src/cli/aws/account.ts
+++ b/src/cli/aws/account.ts
@@ -1,3 +1,4 @@
+import { AwsCredentialsError } from '../../lib/errors/types.js';
 import { getAwsLoginGuidance } from '../external-requirements/checks';
 import { GetCallerIdentityCommand, STSClient } from '@aws-sdk/client-sts';
 import { fromEnv, fromNodeProviderChain } from '@aws-sdk/credential-providers';
@@ -13,21 +14,6 @@ export function getCredentialProvider(): AwsCredentialIdentityProvider {
   return hasEnvCreds ? fromEnv() : fromNodeProviderChain();
 }
 
-/**
- * Error thrown when AWS credentials are not configured or invalid.
- * Supports both a short message (for interactive mode) and detailed message (for CLI mode).
- */
-export class AwsCredentialsError extends Error {
-  /** Short message suitable for interactive mode where UI handles recovery */
-  readonly shortMessage: string;
-
-  constructor(shortMessage: string, detailedMessage?: string) {
-    super(detailedMessage ?? shortMessage);
-    this.name = 'AwsCredentialsError';
-    this.shortMessage = shortMessage;
-  }
-}
-
 /**
  * Get AWS account ID using STS GetCallerIdentity with detailed error handling.
  * Throws AwsCredentialsError with helpful messages for common credential issues.
diff --git a/src/cli/commands/import/phase2-import.ts b/src/cli/commands/import/phase2-import.ts
index c980110bd..a862ac5b3 100644
--- a/src/cli/commands/import/phase2-import.ts
+++ b/src/cli/commands/import/phase2-import.ts
@@ -1,4 +1,5 @@
-import { PollExhaustedError, PollTimeoutError, isThrottlingError, poll } from '../../../lib/utils/polling';
+import { PollExhaustedError, PollTimeoutError } from '../../../lib/errors/types';
+import { isThrottlingError, poll } from '../../../lib/utils/polling';
 import { getCredentialProvider } from '../../aws/account';
 import type { CfnTemplate } from './template-utils';
 import { buildImportTemplate } from './template-utils';
diff --git a/src/cli/operations/dev/__tests__/invoke-a2a.test.ts b/src/cli/operations/dev/__tests__/invoke-a2a.test.ts
index 9428177f6..743c34fc1 100644
--- a/src/cli/operations/dev/__tests__/invoke-a2a.test.ts
+++ b/src/cli/operations/dev/__tests__/invoke-a2a.test.ts
@@ -1,4 +1,4 @@
-import { ServerError } from '../invoke';
+import { ServerError } from '../../../../lib/errors/types';
 import { invokeA2AStreaming } from '../invoke-a2a';
 import { beforeEach, describe, expect, it, vi } from 'vitest';
 
diff --git a/src/cli/operations/dev/__tests__/invoke-mcp.test.ts b/src/cli/operations/dev/__tests__/invoke-mcp.test.ts
index 1ca0758ed..ccba4559c 100644
--- a/src/cli/operations/dev/__tests__/invoke-mcp.test.ts
+++ b/src/cli/operations/dev/__tests__/invoke-mcp.test.ts
@@ -1,4 +1,4 @@
-import { ServerError } from '../invoke';
+import { ServerError } from '../../../../lib/errors/types';
 import { callMcpTool, listMcpTools } from '../invoke-mcp';
 import { beforeEach, describe, expect, it, vi } from 'vitest';
 
diff --git a/src/cli/operations/dev/index.ts b/src/cli/operations/dev/index.ts
index 2522ef21c..e05d67a01 100644
--- a/src/cli/operations/dev/index.ts
+++ b/src/cli/operations/dev/index.ts
@@ -11,7 +11,7 @@ export {
 
 export { getDevConfig, getDevSupportedAgents, getAgentPort, loadProjectConfig, type DevConfig } from './config';
 
-export { ConnectionError, ServerError, invokeAgent, invokeAgentStreaming, invokeForProtocol } from './invoke';
+export { invokeAgent, invokeAgentStreaming, invokeForProtocol } from './invoke';
 
 export { invokeA2AStreaming, fetchA2AAgentCard, type A2AAgentCard } from './invoke-a2a';
 
diff --git a/src/cli/operations/dev/invoke-a2a.ts b/src/cli/operations/dev/invoke-a2a.ts
index ec2a192ea..2b3d28f1d 100644
--- a/src/cli/operations/dev/invoke-a2a.ts
+++ b/src/cli/operations/dev/invoke-a2a.ts
@@ -1,4 +1,5 @@
-import { ConnectionError, type InvokeStreamingOptions, type SSELogger, ServerError } from './invoke-types';
+import { ConnectionError, ServerError } from '../../../lib/errors/types';
+import { type InvokeStreamingOptions, type SSELogger } from './invoke-types';
 import { isConnectionError, sleep } from './utils';
 import { randomUUID } from 'crypto';
 
@@ -153,7 +154,9 @@ export async function* invokeA2AStreaming(options: InvokeStreamingOptions): Asyn
     }
   }
 
-  const finalError = new ConnectionError(lastError ?? new Error('Failed to connect to A2A server after retries'));
+  const finalError = new ConnectionError(lastError?.message ?? 'Failed to connect to A2A server after retries', {
+    cause: lastError,
+  });
   logger?.log?.('error', `Failed to connect after ${maxRetries} attempts: ${finalError.message}`);
   throw finalError;
 }
diff --git a/src/cli/operations/dev/invoke-agui.ts b/src/cli/operations/dev/invoke-agui.ts
index 0349e5271..eb11a5129 100644
--- a/src/cli/operations/dev/invoke-agui.ts
+++ b/src/cli/operations/dev/invoke-agui.ts
@@ -1,6 +1,7 @@
+import { ConnectionError, ServerError } from '../../../lib/errors/types';
 import { parseAguiSSEStream } from '../../aws/agui-parser';
 import { AguiEventType } from '../../aws/agui-types';
-import { ConnectionError, type InvokeStreamingOptions, ServerError } from './invoke-types';
+import { type InvokeStreamingOptions } from './invoke-types';
 import { isConnectionError, sleep } from './utils';
 import { randomUUID } from 'crypto';
 
@@ -147,7 +148,9 @@ export async function* invokeAguiStreaming(options: InvokeStreamingOptions): Asy
     }
   }
 
-  const finalError = new ConnectionError(lastError ?? new Error('Failed to connect to AGUI server after retries'));
+  const finalError = new ConnectionError(lastError?.message ?? 'Failed to connect to AGUI server after retries', {
+    cause: lastError,
+  });
   logger?.log?.('error', `Failed to connect after ${maxRetries} attempts: ${finalError.message}`);
   throw finalError;
 }
diff --git a/src/cli/operations/dev/invoke-mcp.ts b/src/cli/operations/dev/invoke-mcp.ts
index f87971348..6e861ef43 100644
--- a/src/cli/operations/dev/invoke-mcp.ts
+++ b/src/cli/operations/dev/invoke-mcp.ts
@@ -1,5 +1,6 @@
+import { ConnectionError, ServerError } from '../../../lib/errors/types';
 import { parseJsonRpcResponse } from '../../../lib/utils/json-rpc';
-import { ConnectionError, type SSELogger, ServerError } from './invoke-types';
+import { type SSELogger } from './invoke-types';
 import { isConnectionError, sleep } from './utils';
 
 let requestId = 1;
@@ -143,7 +144,9 @@ export async function listMcpTools(
     }
   }
 
-  const finalError = new ConnectionError(lastError ?? new Error('Failed to connect to MCP server after retries'));
+  const finalError = new ConnectionError(lastError?.message ?? 'Failed to connect to MCP server after retries', {
+    cause: lastError,
+  });
   logger?.log?.('error', `Failed to connect after ${maxRetries} attempts: ${finalError.message}`);
   throw finalError;
 }
diff --git a/src/cli/operations/dev/invoke-types.ts b/src/cli/operations/dev/invoke-types.ts
index b876b2b00..4bd2f0a97 100644
--- a/src/cli/operations/dev/invoke-types.ts
+++ b/src/cli/operations/dev/invoke-types.ts
@@ -1,22 +1,3 @@
-/** Error thrown when the dev server returns a non-OK HTTP response. */
-export class ServerError extends Error {
-  constructor(
-    public readonly statusCode: number,
-    body: string
-  ) {
-    super(body || `Server returned ${statusCode}`);
-    this.name = 'ServerError';
-  }
-}
-
-/** Error thrown when the connection to the dev server fails. */
-export class ConnectionError extends Error {
-  constructor(cause: Error) {
-    super(cause.message);
-    this.name = 'ConnectionError';
-  }
-}
-
 /** Logger interface for SSE events and error logging */
 export interface SSELogger {
   logSSEEvent(rawLine: string): void;
diff --git a/src/cli/operations/dev/invoke.ts b/src/cli/operations/dev/invoke.ts
index f676c3ca8..9a385e574 100644
--- a/src/cli/operations/dev/invoke.ts
+++ b/src/cli/operations/dev/invoke.ts
@@ -1,10 +1,10 @@
+import { ConnectionError, ServerError } from '../../../lib/errors/types';
 import { invokeA2AStreaming } from './invoke-a2a';
 import { invokeAguiStreaming } from './invoke-agui';
-import { ConnectionError, type InvokeStreamingOptions, type SSELogger, ServerError } from './invoke-types';
+import { type InvokeStreamingOptions, type SSELogger } from './invoke-types';
 import { isConnectionError, sleep } from './utils';
 
-// Re-export shared types so existing consumers don't break
-export { ConnectionError, ServerError, type InvokeStreamingOptions, type SSELogger } from './invoke-types';
+export { type InvokeStreamingOptions, type SSELogger } from './invoke-types';
 
 /**
  * Parse a single SSE data line and extract the content.
@@ -196,7 +196,9 @@ export async function* invokeAgentStreaming(
   }
 
   // Log final failure after all retries exhausted with full details
-  const finalError = new ConnectionError(lastError ?? new Error('Failed to connect to dev server after retries'));
+  const finalError = new ConnectionError(lastError?.message ?? 'Failed to connect to dev server after retries', {
+    cause: lastError,
+  });
   logger?.log?.('error', `Failed to connect after ${maxRetries} attempts: ${finalError.message}`);
   throw finalError;
 }
@@ -304,7 +306,9 @@ export async function invokeAgent(portOrOptions: number | InvokeOptions, message
   }
 
   // Log final failure after all retries exhausted with full details
-  const finalError = new ConnectionError(lastError ?? new Error('Failed to connect to dev server after retries'));
+  const finalError = new ConnectionError(lastError?.message ?? 'Failed to connect to dev server after retries', {
+    cause: lastError,
+  });
   logger?.log?.('error', `Failed to connect after ${maxRetries} attempts: ${finalError.message}`);
   throw finalError;
 }
diff --git a/src/cli/telemetry/__tests__/client.test.ts b/src/cli/telemetry/__tests__/client.test.ts
index cfba2a0c2..b66111849 100644
--- a/src/cli/telemetry/__tests__/client.test.ts
+++ b/src/cli/telemetry/__tests__/client.test.ts
@@ -1,4 +1,5 @@
 /* eslint-disable @typescript-eslint/require-await */
+import { AccessDeniedError, DependencyCheckError } from '../../../lib/errors/types';
 import { CANCELLED, TelemetryClient } from '../client';
 import { InMemorySink } from '../sinks/in-memory-sink';
 import { describe, expect, it } from 'vitest';
@@ -48,26 +49,19 @@ describe('TelemetryClient', () => {
       });
     });
 
-    it('classifies PackagingError subclasses', async () => {
+    it('classifies DependencyCheckError correctly', async () => {
       const sink = new InMemorySink();
       const client = new TelemetryClient(sink);
 
-      class MissingDependencyError extends Error {
-        constructor() {
-          super('missing dep');
-          this.name = 'MissingDependencyError';
-        }
-      }
-
       await expect(
         client.withCommandRun('deploy', async () => {
-          throw new MissingDependencyError();
+          throw new DependencyCheckError(['missing docker']);
         })
       ).rejects.toThrow();
 
       expect(sink.metrics[0]!.attrs).toMatchObject({
-        error_name: 'PackagingError',
-        is_user_error: 'false',
+        error_name: 'DependencyCheckError',
+        error_source: 'user',
       });
     });
 
@@ -75,22 +69,15 @@ describe('TelemetryClient', () => {
       const sink = new InMemorySink();
       const client = new TelemetryClient(sink);
 
-      class AwsCredentialsError extends Error {
-        constructor() {
-          super('creds expired');
-          this.name = 'AwsCredentialsError';
-        }
-      }
-
       await expect(
         client.withCommandRun('invoke', async () => {
-          throw new AwsCredentialsError();
+          throw new AccessDeniedError('creds expired');
         })
       ).rejects.toThrow();
 
       expect(sink.metrics[0]!.attrs).toMatchObject({
-        error_name: 'CredentialsError',
-        is_user_error: 'true',
+        error_name: 'AccessDeniedError',
+        error_source: 'user',
       });
     });
 
diff --git a/src/cli/telemetry/__tests__/error-classification.test.ts b/src/cli/telemetry/__tests__/error-classification.test.ts
deleted file mode 100644
index 0640e6ce0..000000000
--- a/src/cli/telemetry/__tests__/error-classification.test.ts
+++ /dev/null
@@ -1,63 +0,0 @@
-import { classifyError, isUserError } from '../error-classification';
-import { describe, expect, it } from 'vitest';
-
-function errorWithName(name: string): Error {
-  const err = new Error('test');
-  err.name = name;
-  return err;
-}
-
-describe('classifyError', () => {
-  it.each([
-    ['ConfigValidationError', 'ConfigError'],
-    ['ConfigNotFoundError', 'ConfigError'],
-    ['ConfigReadError', 'ConfigError'],
-    ['ConfigWriteError', 'ConfigError'],
-    ['ConfigParseError', 'ConfigError'],
-    ['AwsCredentialsError', 'CredentialsError'],
-    ['AccessDeniedException', 'CredentialsError'],
-    ['ExpiredToken', 'CredentialsError'],
-    ['PackagingError', 'PackagingError'],
-    ['MissingDependencyError', 'PackagingError'],
-    ['ArtifactSizeError', 'PackagingError'],
-    ['NoProjectError', 'ProjectError'],
-    ['AgentAlreadyExistsError', 'ProjectError'],
-    ['ResourceNotFoundException', 'ServiceError'],
-    ['ValidationException', 'ServiceError'],
-    ['ConflictException', 'ServiceError'],
-    ['ConnectionError', 'ConnectionError'],
-    ['ServerError', 'ConnectionError'],
-  ] as const)('%s → %s', (errorName, expected) => {
-    expect(classifyError(errorWithName(errorName))).toBe(expected);
-  });
-
-  it('returns UnknownError for unrecognized errors', () => {
-    expect(classifyError(new Error('something'))).toBe('UnknownError');
-  });
-
-  it('returns UnknownError for non-Error values', () => {
-    expect(classifyError('string')).toBe('UnknownError');
-    expect(classifyError(null)).toBe('UnknownError');
-    expect(classifyError(undefined)).toBe('UnknownError');
-  });
-
-  it('uses err.name when constructor.name is Error (SDK pattern)', () => {
-    // AWS SDK errors often: new Error(); err.name = 'ValidationException'
-    expect(classifyError(errorWithName('ValidationException'))).toBe('ServiceError');
-  });
-});
-
-describe('isUserError', () => {
-  it('returns true for user-fixable categories', () => {
-    expect(isUserError(errorWithName('ConfigValidationError'))).toBe(true);
-    expect(isUserError(errorWithName('AwsCredentialsError'))).toBe(true);
-    expect(isUserError(errorWithName('NoProjectError'))).toBe(true);
-  });
-
-  it('returns false for system categories', () => {
-    expect(isUserError(errorWithName('PackagingError'))).toBe(false);
-    expect(isUserError(errorWithName('ResourceNotFoundException'))).toBe(false);
-    expect(isUserError(errorWithName('ConnectionError'))).toBe(false);
-    expect(isUserError(new Error('unknown'))).toBe(false);
-  });
-});
diff --git a/src/cli/telemetry/client.ts b/src/cli/telemetry/client.ts
index 2341231ea..14082ac42 100644
--- a/src/cli/telemetry/client.ts
+++ b/src/cli/telemetry/client.ts
@@ -1,4 +1,4 @@
-import { classifyError, isUserError } from './error-classification.js';
+import { classifyError } from './error.js';
 import { COMMAND_SCHEMAS, type Command, type CommandAttrs, deriveCommandGroup } from './schemas/command-run.js';
 import { type CommandResult, CommandResultSchema, resilientParse } from './schemas/common-shapes.js';
 import type { MetricSink } from './sinks/metric-sink.js';
@@ -39,10 +39,11 @@ export class TelemetryClient {
         this.recordCommandRun(command, { exit_reason: 'success' }, result, durationMs);
       }
     } catch (err) {
+      const { category, source } = classifyError(err);
       const failureResult: CommandResult & { exit_reason: 'failure' } = {
         exit_reason: 'failure',
-        error_name: classifyError(err),
-        is_user_error: isUserError(err),
+        error_name: category,
+        error_source: source,
       };
       this.recordCommandRun(command, failureResult, fallbackAttrs ?? {}, Math.round(performance.now() - start));
       throw err;
diff --git a/src/cli/telemetry/error-classification.ts b/src/cli/telemetry/error-classification.ts
deleted file mode 100644
index 1f5627699..000000000
--- a/src/cli/telemetry/error-classification.ts
+++ /dev/null
@@ -1,67 +0,0 @@
-import { type ErrorCategory } from './schemas/common-shapes.js';
-import type { z } from 'zod';
-
-type ErrorCategoryValue = z.infer<typeof ErrorCategory>;
-
-const CONFIG_ERRORS = new Set([
-  'ConfigValidationError',
-  'ConfigNotFoundError',
-  'ConfigReadError',
-  'ConfigWriteError',
-  'ConfigParseError',
-  'ValidationError',
-]);
-const PACKAGING_ERRORS = new Set([
-  'PackagingError',
-  'MissingDependencyError',
-  'MissingProjectFileError',
-  'UnsupportedLanguageError',
-  'ArtifactSizeError',
-  'DependencyCheckError',
-]);
-const CREDENTIAL_ERRORS = new Set([
-  'AwsCredentialsError',
-  'AccessDeniedException',
-  'AccessDenied',
-  'AccessDeniedError',
-  'ExpiredToken',
-  'ExpiredTokenException',
-  'TokenRefreshRequired',
-  'CredentialsExpired',
-  'InvalidIdentityToken',
-  'UnauthorizedAccess',
-  'InvalidClientTokenId',
-]);
-const PROJECT_ERRORS = new Set(['NoProjectError', 'AgentAlreadyExistsError']);
-const CONNECTION_ERRORS = new Set(['ConnectionError', 'ServerError']);
-const SERVICE_ERRORS = new Set([
-  'ResourceNotFoundException',
-  'ValidationException',
-  'ConflictException',
-  'ResourceAlreadyExistsException',
-  'ResourceNotFoundError',
-  'ConflictError',
-]);
-
-const USER_CATEGORIES = new Set<ErrorCategoryValue>(['ConfigError', 'CredentialsError', 'ProjectError']);
-
-export function classifyError(err: unknown): ErrorCategoryValue {
-  if (!(err instanceof Error)) return 'UnknownError';
-  const name =
-    err.constructor.name === 'Error'
-      ? 'name' in err && typeof err.name === 'string'
-        ? err.name
-        : 'Error'
-      : err.constructor.name;
-  if (CONFIG_ERRORS.has(name)) return 'ConfigError';
-  if (CREDENTIAL_ERRORS.has(name)) return 'CredentialsError';
-  if (PACKAGING_ERRORS.has(name)) return 'PackagingError';
-  if (PROJECT_ERRORS.has(name)) return 'ProjectError';
-  if (SERVICE_ERRORS.has(name)) return 'ServiceError';
-  if (CONNECTION_ERRORS.has(name)) return 'ConnectionError';
-  return 'UnknownError';
-}
-
-export function isUserError(err: unknown): boolean {
-  return USER_CATEGORIES.has(classifyError(err));
-}
diff --git a/src/cli/telemetry/error.ts b/src/cli/telemetry/error.ts
new file mode 100644
index 000000000..91bc83029
--- /dev/null
+++ b/src/cli/telemetry/error.ts
@@ -0,0 +1,33 @@
+import { BaseError, type ErrorSource } from '../../lib/errors/types.js';
+import { ErrorName } from './schemas/common-shapes.js';
+import type { z } from 'zod';
+
+type ErrorNameValue = z.infer<typeof ErrorName>;
+
+// Maps common AWS SDK error names to a category and source.
+const SDK_ERROR_MAP: Record<string, { category: ErrorNameValue; source: ErrorSource }> = {
+  AccessDeniedException: { category: 'AccessDeniedError', source: 'user' },
+  AccessDenied: { category: 'AccessDeniedError', source: 'user' },
+  ExpiredToken: { category: 'AwsCredentialsError', source: 'user' },
+  ExpiredTokenException: { category: 'AwsCredentialsError', source: 'user' },
+  InvalidClientTokenId: { category: 'AwsCredentialsError', source: 'user' },
+  TokenRefreshRequired: { category: 'AwsCredentialsError', source: 'user' },
+  CredentialsExpired: { category: 'AwsCredentialsError', source: 'user' },
+  InvalidIdentityToken: { category: 'AwsCredentialsError', source: 'user' },
+  UnauthorizedAccess: { category: 'AwsCredentialsError', source: 'user' },
+  ValidationException: { category: 'ValidationError', source: 'user' },
+  ResourceNotFoundException: { category: 'ResourceNotFoundError', source: 'user' },
+  ConflictException: { category: 'ConflictError', source: 'user' },
+  ResourceAlreadyExistsException: { category: 'ConflictError', source: 'user' },
+};
+
+export function classifyError(err: unknown): { category: ErrorNameValue; source: ErrorSource } {
+  if (err instanceof BaseError) {
+    const parsed = ErrorName.safeParse(err.name);
+    return { category: parsed.success ? parsed.data : 'UnknownError', source: err.errorSource };
+  }
+  if (err instanceof Error && err.name in SDK_ERROR_MAP) {
+    return SDK_ERROR_MAP[err.name]!;
+  }
+  return { category: 'UnknownError', source: 'unknown' };
+}
diff --git a/src/cli/telemetry/index.ts b/src/cli/telemetry/index.ts
index 778376713..911141c6e 100644
--- a/src/cli/telemetry/index.ts
+++ b/src/cli/telemetry/index.ts
@@ -5,4 +5,3 @@ export { TelemetryClient, CANCELLED } from './client.js';
 export { type MetricSink, CompositeSink } from './sinks/metric-sink.js';
 export { OtelMetricSink, type OtelMetricSinkConfig } from './sinks/otel-metric-sink.js';
 export { FileSystemSink, type FileSystemSinkConfig } from './sinks/filesystem-sink.js';
-export { classifyError, isUserError } from './error-classification.js';
diff --git a/src/cli/telemetry/schemas/__tests__/command-run.test.ts b/src/cli/telemetry/schemas/__tests__/command-run.test.ts
index eae73cabc..e0ad17f25 100644
--- a/src/cli/telemetry/schemas/__tests__/command-run.test.ts
+++ b/src/cli/telemetry/schemas/__tests__/command-run.test.ts
@@ -12,10 +12,10 @@ describe('CommandResultSchema', () => {
   it('accepts failure with required error fields', () => {
     const result = CommandResultSchema.parse({
       exit_reason: 'failure',
-      error_name: 'PackagingError',
-      is_user_error: false,
+      error_name: 'DependencyCheckError',
+      error_source: 'user',
     });
-    expect(result).toMatchObject({ exit_reason: 'failure', error_name: 'PackagingError' });
+    expect(result).toMatchObject({ exit_reason: 'failure', error_name: 'DependencyCheckError' });
   });
 
   it('rejects failure missing error_name', () => {
diff --git a/src/cli/telemetry/schemas/common-shapes.ts b/src/cli/telemetry/schemas/common-shapes.ts
index 429716096..d9622512a 100644
--- a/src/cli/telemetry/schemas/common-shapes.ts
+++ b/src/cli/telemetry/schemas/common-shapes.ts
@@ -101,23 +101,43 @@ export const ResourceType = z.enum(['gateway', 'agent']);
 export const SourceType = z.enum(['file', 'statement', 'generate']);
 export const ValidationMode = z.enum(['fail_on_any_findings', 'ignore_all_findings']);
 
-export const ErrorCategory = z.enum([
-  'ConfigError',
-  'CredentialsError',
-  'PackagingError',
-  'ProjectError',
-  'ServiceError',
+export const ErrorName = z.enum([
+  'AccessDeniedError',
+  'AgentAlreadyExistsError',
+  'ArtifactSizeError',
+  'AwsCredentialsError',
+  'ConfigNotFoundError',
+  'ConfigParseError',
+  'ConfigReadError',
+  'ConfigValidationError',
+  'ConfigWriteError',
+  'ConflictError',
   'ConnectionError',
+  'DependencyCheckError',
+  'GitInitError',
+  'MissingDependencyError',
+  'MissingProjectFileError',
+  'NoProjectError',
+  'PackagingError',
+  'PollExhaustedError',
+  'PollTimeoutError',
+  'ResourceNotFoundError',
+  'ServerError',
+  'TimeoutError',
+  'UnsupportedLanguageError',
+  'ValidationError',
   'UnknownError',
 ]);
 
+export const ErrorSource = z.enum(['user', 'client', 'service', 'unknown']);
+
 // Common result shapes — reusable across metrics
 export const SuccessResult = z.object({ exit_reason: z.literal('success') });
 export const CancelResult = z.object({ exit_reason: z.literal('cancel') });
 export const FailureResult = z.object({
   exit_reason: z.literal('failure'),
-  error_name: ErrorCategory,
-  is_user_error: z.boolean(),
+  error_name: ErrorName,
+  error_source: ErrorSource,
 });
 export const CommandResultSchema = z.discriminatedUnion('exit_reason', [SuccessResult, CancelResult, FailureResult]);
 export type CommandResult = z.infer<typeof CommandResultSchema>;
diff --git a/src/cli/telemetry/schemas/index.ts b/src/cli/telemetry/schemas/index.ts
index 7110f61d9..dd921df7a 100644
--- a/src/cli/telemetry/schemas/index.ts
+++ b/src/cli/telemetry/schemas/index.ts
@@ -1,7 +1,8 @@
 export {
   CommandResultSchema,
   Count,
-  ErrorCategory,
+  ErrorName,
+  ErrorSource,
   ExitReason,
   FailureResult,
   Mode,
diff --git a/src/cli/tui/hooks/useCdkPreflight.ts b/src/cli/tui/hooks/useCdkPreflight.ts
index 062da752f..4602c1c14 100644
--- a/src/cli/tui/hooks/useCdkPreflight.ts
+++ b/src/cli/tui/hooks/useCdkPreflight.ts
@@ -1,7 +1,8 @@
 import { ConfigIO, SecureCredentials } from '../../../lib';
+import { AwsCredentialsError } from '../../../lib/errors/types';
 import type { DeployedState } from '../../../schema';
 import { applyTargetRegionToEnv } from '../../aws';
-import { AwsCredentialsError, validateAwsCredentials } from '../../aws/account';
+import { validateAwsCredentials } from '../../aws/account';
 import { type CdkToolkitWrapper, type SwitchableIoHost, createSwitchableIoHost } from '../../cdk/toolkit-lib';
 import { getErrorMessage, isExpiredTokenError, isNoCredentialsError } from '../../errors';
 import type { ExecLogger } from '../../logging';
diff --git a/src/cli/tui/hooks/useDevServer.ts b/src/cli/tui/hooks/useDevServer.ts
index c964b2419..d5a6f0075 100644
--- a/src/cli/tui/hooks/useDevServer.ts
+++ b/src/cli/tui/hooks/useDevServer.ts
@@ -1,15 +1,14 @@
 import { findConfigRoot } from '../../../lib';
+import { ConnectionError, ServerError } from '../../../lib/errors/types';
 import type { AgentCoreProjectSpec, ProtocolMode } from '../../../schema';
 import { detectContainerRuntime } from '../../external-requirements';
 import { DevLogger } from '../../logging/dev-logger';
 import {
   type A2AAgentCard,
-  ConnectionError,
   type DevConfig,
   DevServer,
   type LogLevel,
   type McpTool,
-  ServerError,
   callMcpTool,
   createDevServer,
   fetchA2AAgentCard,
diff --git a/src/lib/errors/__tests__/config.test.ts b/src/lib/errors/__tests__/config.test.ts
index 365afc7f5..ffba67445 100644
--- a/src/lib/errors/__tests__/config.test.ts
+++ b/src/lib/errors/__tests__/config.test.ts
@@ -5,7 +5,7 @@ import {
   ConfigReadError,
   ConfigValidationError,
   ConfigWriteError,
-} from '../config.js';
+} from '../types.js';
 import { describe, expect, it } from 'vitest';
 import { ZodError, ZodIssueCode, z } from 'zod';
 
diff --git a/src/lib/errors/index.ts b/src/lib/errors/index.ts
index 2acd167c8..fcb073fef 100644
--- a/src/lib/errors/index.ts
+++ b/src/lib/errors/index.ts
@@ -1,2 +1 @@
-export * from './config';
 export * from './types';
diff --git a/src/lib/errors/types.ts b/src/lib/errors/types.ts
index ca6bfded5..16940a3d2 100644
--- a/src/lib/errors/types.ts
+++ b/src/lib/errors/types.ts
@@ -1,104 +1,292 @@
+import { formatZodErrors } from './zod.js';
+import { ZodError } from 'zod';
+
+export type ErrorSource = 'user' | 'client' | 'service' | 'unknown';
+
+export interface BaseErrorOptions extends ErrorOptions {
+  errorSource?: ErrorSource;
+}
+
+interface InternalErrorOptions extends BaseErrorOptions {
+  defaultSource: ErrorSource;
+}
+
+export abstract class BaseError extends Error {
+  readonly errorSource: ErrorSource;
+
+  protected constructor(message: string, options: InternalErrorOptions) {
+    super(message, options);
+    this.name = this.constructor.name;
+    this.errorSource = options.errorSource ?? options.defaultSource;
+  }
+}
+
+/**
+ * Converts an unknown thrown value to an Error instance.
+ * Use in catch blocks to ensure the error field is always an Error object.
+ */
+export function toError(err: unknown): Error {
+  return err instanceof Error ? err : new Error(String(err));
+}
+
+// --- User errors ---
+
 /**
  * Error indicating no agentcore project was found in the working directory.
  */
-export class NoProjectError extends Error {
-  constructor(message?: string) {
-    super(message ?? 'No agentcore project found. Run "agentcore create" first.');
-    this.name = 'NoProjectError';
+export class NoProjectError extends BaseError {
+  constructor(message?: string, options?: BaseErrorOptions) {
+    super(message ?? 'No agentcore project found. Run "agentcore create" first.', {
+      defaultSource: 'user',
+      ...options,
+    });
   }
 }
 
 /**
  * Error thrown when an agent with the same name already exists.
  */
-export class AgentAlreadyExistsError extends Error {
-  constructor(agentName: string) {
-    super(`An agent named "${agentName}" already exists in the schema.`);
-    this.name = 'AgentAlreadyExistsError';
+export class AgentAlreadyExistsError extends BaseError {
+  constructor(agentName: string, options?: BaseErrorOptions) {
+    super(`An agent named "${agentName}" already exists in the schema.`, { defaultSource: 'user', ...options });
   }
 }
 
 /**
  * Error indicating an AWS permissions failure (AccessDenied / AccessDeniedException).
  */
-export class AccessDeniedError extends Error {
-  constructor(message: string, options?: ErrorOptions) {
-    super(message, options);
-    this.name = 'AccessDeniedError';
+export class AccessDeniedError extends BaseError {
+  constructor(message: string, options?: BaseErrorOptions) {
+    super(message, { defaultSource: 'user', ...options });
   }
 }
 
 /**
  * Error indicating missing system dependencies required for an operation.
  */
-export class DependencyCheckError extends Error {
-  constructor(errors: string[]) {
-    super(errors.join('\n'));
-    this.name = 'DependencyCheckError';
+export class DependencyCheckError extends BaseError {
+  constructor(errors: string[], options?: BaseErrorOptions) {
+    super(errors.join('\n'), { defaultSource: 'user', ...options });
   }
 }
 
 /**
- * Error indicating git repository initialization failed.
+ * Error indicating a referenced resource could not be found.
  */
-export class GitInitError extends Error {
-  constructor(message: string) {
-    super(message);
-    this.name = 'GitInitError';
+export class ResourceNotFoundError extends BaseError {
+  constructor(message: string, options?: BaseErrorOptions) {
+    super(message, { defaultSource: 'user', ...options });
   }
 }
 
 /**
- * Error indicating a referenced resource could not be found.
+ * Error indicating invalid input or configuration values.
  */
-export class ResourceNotFoundError extends Error {
-  constructor(message: string) {
-    super(message);
-    this.name = 'ResourceNotFoundError';
+export class ValidationError extends BaseError {
+  constructor(message: string, options?: BaseErrorOptions) {
+    super(message, { defaultSource: 'user', ...options });
   }
 }
 
-export class ValidationError extends Error {
-  constructor(message: string, options?: ErrorOptions) {
-    super(message, options);
-    this.name = 'ValidationError';
+/**
+ * Error thrown when AWS credentials are not configured or invalid.
+ * Supports both a short message (for interactive mode) and detailed message (for CLI mode).
+ */
+export class AwsCredentialsError extends BaseError {
+  readonly shortMessage: string;
+  constructor(shortMessage: string, detailedMessage?: string, options?: BaseErrorOptions) {
+    super(detailedMessage ?? shortMessage, { defaultSource: 'user', ...options });
+    this.shortMessage = shortMessage;
   }
 }
 
 /**
- * Error indicating a network connection failure (e.g., server not reachable).
+ * Error indicating a packaging operation failed.
  */
-export class ConnectionError extends Error {
-  constructor(message: string, options?: ErrorOptions) {
-    super(message, options);
-    this.name = 'ConnectionError';
+export class PackagingError extends BaseError {
+  constructor(message: string, options?: BaseErrorOptions) {
+    super(message, { defaultSource: 'user', ...options });
   }
 }
 
 /**
- * Converts an unknown thrown value to an Error instance.
- * Use in catch blocks to ensure the error field is always an Error object.
+ * Error indicating the packaged artifact exceeds the size limit.
  */
-export function toError(err: unknown): Error {
-  return err instanceof Error ? err : new Error(String(err));
+export class ArtifactSizeError extends PackagingError {
+  constructor(limitBytes: number, actualBytes: number, options?: BaseErrorOptions) {
+    super(`Packaged artifact exceeds ${limitBytes} bytes (actual: ${actualBytes}).`, options);
+  }
+}
+
+/**
+ * Error indicating a required binary or tool is not installed.
+ */
+export class MissingDependencyError extends PackagingError {
+  constructor(binary: string, installHint?: string, options?: BaseErrorOptions) {
+    super(installHint ? `${binary} is required. ${installHint}` : `${binary} is required.`, options);
+  }
+}
+
+/**
+ * Error indicating a required project file is missing.
+ */
+export class MissingProjectFileError extends PackagingError {
+  constructor(filePath: string, options?: BaseErrorOptions) {
+    super(`Required project file not found: ${filePath}`, options);
+  }
+}
+
+/**
+ * Error indicating the project language is not supported for packaging.
+ */
+export class UnsupportedLanguageError extends PackagingError {
+  constructor(language: string, options?: BaseErrorOptions) {
+    super(`${language} packaging is not supported yet.`, options);
+  }
+}
+
+// --- Config errors (user) ---
+
+/**
+ * Base class for all config-related errors.
+ */
+export abstract class ConfigError extends BaseError {
+  protected constructor(message: string, options?: BaseErrorOptions) {
+    super(message, { defaultSource: 'user', ...options });
+  }
 }
 
+/**
+ * Thrown when a config file doesn't exist.
+ */
+export class ConfigNotFoundError extends ConfigError {
+  constructor(
+    public readonly filePath: string,
+    public readonly fileType: string
+  ) {
+    super(`${fileType} config file not found at: ${filePath}`);
+  }
+}
+
+/**
+ * Thrown when a config file can't be read.
+ */
+export class ConfigReadError extends ConfigError {
+  constructor(
+    public readonly filePath: string,
+    public override readonly cause: unknown
+  ) {
+    const message = cause instanceof Error ? cause.message : String(cause);
+    super(`Failed to read config file at ${filePath}: ${message}`);
+  }
+}
+
+/**
+ * Thrown when a config file can't be written.
+ */
+export class ConfigWriteError extends ConfigError {
+  constructor(
+    public readonly filePath: string,
+    public override readonly cause: unknown
+  ) {
+    const message = cause instanceof Error ? cause.message : String(cause);
+    super(`Failed to write config file at ${filePath}: ${message}`);
+  }
+}
+
+/**
+ * Thrown when config validation fails.
+ */
+export class ConfigValidationError extends ConfigError {
+  constructor(
+    public readonly filePath: string,
+    public readonly fileType: string,
+    public readonly zodError: ZodError
+  ) {
+    super(`${filePath}:\n${formatZodErrors(zodError.issues)}`);
+  }
+}
+
+/**
+ * Thrown when JSON parsing fails.
+ */
+export class ConfigParseError extends ConfigError {
+  constructor(
+    public readonly filePath: string,
+    public override readonly cause: unknown
+  ) {
+    const message = cause instanceof Error ? cause.message : String(cause);
+    super(`Failed to parse JSON in config file at ${filePath}: ${message}`);
+  }
+}
+
+// --- Client errors ---
+
+/**
+ * Error indicating git repository initialization failed.
+ */
+export class GitInitError extends BaseError {
+  constructor(message: string, options?: BaseErrorOptions) {
+    super(message, { defaultSource: 'client', ...options });
+  }
+}
+
+// --- Service errors ---
+
 /**
  * Error indicating a resource conflict (e.g., already exists).
  */
-export class ConflictError extends Error {
-  constructor(message: string) {
-    super(message);
-    this.name = 'ConflictError';
+export class ConflictError extends BaseError {
+  constructor(message: string, options?: BaseErrorOptions) {
+    super(message, { defaultSource: 'user', ...options });
   }
 }
 
 /**
  * Error indicating an operation timed out or exceeded retry limits.
  */
-export class TimeoutError extends Error {
-  constructor(message: string) {
-    super(message);
-    this.name = 'TimeoutError';
+export class TimeoutError extends BaseError {
+  constructor(message: string, options?: BaseErrorOptions) {
+    super(message, { defaultSource: 'service', ...options });
+  }
+}
+
+/**
+ * Error thrown when the dev server returns a non-OK HTTP response.
+ */
+export class ServerError extends BaseError {
+  constructor(
+    public readonly statusCode: number,
+    body: string,
+    options?: BaseErrorOptions
+  ) {
+    super(body || `Server returned ${statusCode}`, { defaultSource: 'client', ...options });
+  }
+}
+
+/**
+ * Error thrown when the connection to the dev server fails.
+ */
+export class ConnectionError extends BaseError {
+  constructor(message: string, options?: BaseErrorOptions) {
+    super(message, { defaultSource: 'client', ...options });
+  }
+}
+
+/**
+ * Error indicating polling timed out.
+ */
+export class PollTimeoutError extends BaseError {
+  constructor(timeoutMs: number, options?: BaseErrorOptions) {
+    super(`Polling timed out after ${timeoutMs}ms`, { defaultSource: 'service', ...options });
+  }
+}
+
+/**
+ * Error indicating polling exhausted all retry attempts.
+ */
+export class PollExhaustedError extends BaseError {
+  constructor(maxAttempts: number, options?: BaseErrorOptions) {
+    super(`Polling exhausted after ${maxAttempts} attempts`, { defaultSource: 'service', ...options });
   }
 }
diff --git a/src/lib/errors/config.ts b/src/lib/errors/zod.ts
similarity index 64%
rename from src/lib/errors/config.ts
rename to src/lib/errors/zod.ts
index 4d7ccebe0..e940c308e 100644
--- a/src/lib/errors/config.ts
+++ b/src/lib/errors/zod.ts
@@ -1,65 +1,6 @@
-import { ZodError } from 'zod';
-
-/**
- * Base class for all config-related errors
- */
-export abstract class ConfigError extends Error {
-  protected constructor(message: string) {
-    super(message);
-    this.name = this.constructor.name;
-    Error.captureStackTrace(this, this.constructor);
-  }
-}
-
-/**
- * Thrown when a config file doesn't exist
- */
-export class ConfigNotFoundError extends ConfigError {
-  constructor(
-    public readonly filePath: string,
-    public readonly fileType: string
-  ) {
-    super(`${fileType} config file not found at: ${filePath}`);
-  }
-}
-
-/**
- * Thrown when a config file can't be read
- */
-export class ConfigReadError extends ConfigError {
-  constructor(
-    public readonly filePath: string,
-    public override readonly cause: unknown
-  ) {
-    const message = cause instanceof Error ? cause.message : String(cause);
-    super(`Failed to read config file at ${filePath}: ${message}`);
-  }
-}
-
-/**
- * Thrown when a config file can't be written
- */
-export class ConfigWriteError extends ConfigError {
-  constructor(
-    public readonly filePath: string,
-    public override readonly cause: unknown
-  ) {
-    const message = cause instanceof Error ? cause.message : String(cause);
-    super(`Failed to write config file at ${filePath}: ${message}`);
-  }
-}
-
 /**
- * Format a Zod path array to bracket notation: agents[0].name
+ * Zod error formatting utilities for human-readable validation messages.
  */
-function formatPath(path: PropertyKey[]): string {
-  if (path.length === 0) return 'root';
-  return path
-    .map((segment, i) =>
-      typeof segment === 'number' ? `[${segment}]` : i === 0 ? String(segment) : `.${String(segment)}`
-    )
-    .join('');
-}
 
 // Zod issue with extended properties for type-safe access (Zod 4 compatible)
 interface ZodIssueExt {
@@ -76,6 +17,18 @@ interface ZodIssueExt {
   discriminator?: string; // Zod 4 discriminated union
 }
 
+/**
+ * Format a Zod path array to bracket notation: agents[0].name
+ */
+function formatPath(path: PropertyKey[]): string {
+  if (path.length === 0) return 'root';
+  return path
+    .map((segment, i) =>
+      typeof segment === 'number' ? `[${segment}]` : i === 0 ? String(segment) : `.${String(segment)}`
+    )
+    .join('');
+}
+
 /**
  * Format a single Zod issue into an actionable message.
  * Augments common cases with "got X, expected Y" format.
@@ -158,28 +111,8 @@ function formatZodIssue(issue: ZodIssueExt): string {
 }
 
 /**
- * Thrown when config validation fails
+ * Format all issues from a ZodError into a newline-separated list.
  */
-export class ConfigValidationError extends ConfigError {
-  constructor(
-    public readonly filePath: string,
-    public readonly fileType: string,
-    public readonly zodError: ZodError
-  ) {
-    const formattedErrors = (zodError.issues as ZodIssueExt[]).map(issue => `  - ${formatZodIssue(issue)}`).join('\n');
-    super(`${filePath}:\n${formattedErrors}`);
-  }
-}
-
-/**
- * Thrown when JSON parsing fails
- */
-export class ConfigParseError extends ConfigError {
-  constructor(
-    public readonly filePath: string,
-    public override readonly cause: unknown
-  ) {
-    const message = cause instanceof Error ? cause.message : String(cause);
-    super(`Failed to parse JSON in config file at ${filePath}: ${message}`);
-  }
+export function formatZodErrors(issues: unknown[]): string {
+  return (issues as ZodIssueExt[]).map(issue => `  - ${formatZodIssue(issue)}`).join('\n');
 }
diff --git a/src/lib/packaging/__tests__/errors.test.ts b/src/lib/packaging/__tests__/errors.test.ts
index e6d07805b..2394126cf 100644
--- a/src/lib/packaging/__tests__/errors.test.ts
+++ b/src/lib/packaging/__tests__/errors.test.ts
@@ -4,7 +4,7 @@ import {
   MissingProjectFileError,
   PackagingError,
   UnsupportedLanguageError,
-} from '../errors.js';
+} from '../../errors/types.js';
 import { describe, expect, it } from 'vitest';
 
 describe('PackagingError', () => {
diff --git a/src/lib/packaging/container.ts b/src/lib/packaging/container.ts
index a166a08f3..fc9400a86 100644
--- a/src/lib/packaging/container.ts
+++ b/src/lib/packaging/container.ts
@@ -1,7 +1,7 @@
 import type { AgentEnvSpec } from '../../schema';
 import { CONTAINER_RUNTIMES, DOCKERFILE_NAME, ONE_GB, getDockerfilePath } from '../constants';
+import { PackagingError } from '../errors/types';
 import { getUvBuildArgs } from './build-args';
-import { PackagingError } from './errors';
 import { resolveCodeLocation } from './helpers';
 import type { ArtifactResult, PackageOptions, RuntimePackager } from './types/packaging';
 import { spawnSync } from 'child_process';
diff --git a/src/lib/packaging/errors.ts b/src/lib/packaging/errors.ts
deleted file mode 100644
index e88701ce2..000000000
--- a/src/lib/packaging/errors.ts
+++ /dev/null
@@ -1,31 +0,0 @@
-export class PackagingError extends Error {
-  constructor(message: string) {
-    super(message);
-    this.name = this.constructor.name;
-    Error.captureStackTrace(this, this.constructor);
-  }
-}
-
-export class MissingDependencyError extends PackagingError {
-  constructor(binary: string, installHint?: string) {
-    super(installHint ? `${binary} is required. ${installHint}` : `${binary} is required.`);
-  }
-}
-
-export class MissingProjectFileError extends PackagingError {
-  constructor(filePath: string) {
-    super(`Required project file not found: ${filePath}`);
-  }
-}
-
-export class UnsupportedLanguageError extends PackagingError {
-  constructor(language: string) {
-    super(`${language} packaging is not supported yet.`);
-  }
-}
-
-export class ArtifactSizeError extends PackagingError {
-  constructor(limitBytes: number, actualBytes: number) {
-    super(`Packaged artifact exceeds ${limitBytes} bytes (actual: ${actualBytes}).`);
-  }
-}
diff --git a/src/lib/packaging/helpers.ts b/src/lib/packaging/helpers.ts
index 6f871c410..caa3d3792 100644
--- a/src/lib/packaging/helpers.ts
+++ b/src/lib/packaging/helpers.ts
@@ -1,8 +1,8 @@
 import type { RuntimeVersion } from '../../schema';
 import { CONFIG_DIR } from '../constants';
+import { ArtifactSizeError, MissingDependencyError, MissingProjectFileError } from '../errors/types';
 import { isWindows } from '../utils/platform';
 import { checkSubprocess, checkSubprocessSync, runSubprocess } from '../utils/subprocess';
-import { ArtifactSizeError, MissingDependencyError, MissingProjectFileError } from './errors';
 import type { PackageOptions } from './types/packaging';
 import type { Zippable } from 'fflate';
 import { zipSync } from 'fflate';
diff --git a/src/lib/packaging/index.ts b/src/lib/packaging/index.ts
index a281bbdbb..8c3067ca3 100644
--- a/src/lib/packaging/index.ts
+++ b/src/lib/packaging/index.ts
@@ -1,7 +1,7 @@
 import type { AgentCoreProjectSpec, AgentEnvSpec, RuntimeVersion } from '../../schema';
 import { DEFAULT_PYTHON_VERSION } from '../../schema';
+import { PackagingError } from '../errors/types';
 import { ContainerPackager } from './container';
-import { PackagingError } from './errors';
 import { isNodeRuntime, isPythonRuntime } from './helpers';
 import { NodeCodeZipPackager, NodeCodeZipPackagerSync } from './node';
 import { PythonCodeZipPackager, PythonCodeZipPackagerSync } from './python';
@@ -91,5 +91,5 @@ export type {
   PackageOptions,
   RuntimePackager,
 } from './types/packaging';
-export * from './errors';
+
 export { resolveCodeLocation } from './helpers';
diff --git a/src/lib/packaging/node.ts b/src/lib/packaging/node.ts
index 2d12e5cd7..38f6efec2 100644
--- a/src/lib/packaging/node.ts
+++ b/src/lib/packaging/node.ts
@@ -1,6 +1,6 @@
 import type { AgentEnvSpec, NodeRuntime, RuntimeVersion } from '../../schema';
 import { getArtifactZipName } from '../constants';
-import { PackagingError } from './errors';
+import { PackagingError } from '../errors/types';
 import {
   createZipFromDir,
   createZipFromDirSync,
diff --git a/src/lib/packaging/python.ts b/src/lib/packaging/python.ts
index eac12567f..0e4a7b2c3 100644
--- a/src/lib/packaging/python.ts
+++ b/src/lib/packaging/python.ts
@@ -1,8 +1,8 @@
 import type { AgentEnvSpec, PythonRuntime, RuntimeVersion } from '../../schema';
 import { DEFAULT_PYTHON_VERSION } from '../../schema';
 import { UV_INSTALL_HINT, getArtifactZipName } from '../constants';
+import { PackagingError } from '../errors/types';
 import { runSubprocessCapture, runSubprocessCaptureSync } from '../utils/subprocess';
-import { PackagingError } from './errors';
 import {
   convertWindowsScriptsToLinux,
   convertWindowsScriptsToLinuxSync,
diff --git a/src/lib/schemas/io/__tests__/config-io.test.ts b/src/lib/schemas/io/__tests__/config-io.test.ts
index 99e885e28..a41edb28d 100644
--- a/src/lib/schemas/io/__tests__/config-io.test.ts
+++ b/src/lib/schemas/io/__tests__/config-io.test.ts
@@ -1,5 +1,5 @@
 import { NoProjectError } from '../../../errors';
-import { ConfigNotFoundError, ConfigParseError, ConfigValidationError } from '../../../errors/config.js';
+import { ConfigNotFoundError, ConfigParseError, ConfigValidationError } from '../../../errors/types.js';
 import { ConfigIO } from '../config-io.js';
 import { randomUUID } from 'node:crypto';
 import { existsSync, mkdirSync, writeFileSync } from 'node:fs';
diff --git a/src/lib/schemas/io/config-io.ts b/src/lib/schemas/io/config-io.ts
index 37cc728c8..25841f4d8 100644
--- a/src/lib/schemas/io/config-io.ts
+++ b/src/lib/schemas/io/config-io.ts
@@ -12,8 +12,8 @@ import {
   ConfigReadError,
   ConfigValidationError,
   ConfigWriteError,
+  NoProjectError,
 } from '../../errors';
-import { NoProjectError } from '../../errors';
 import { detectAwsAccount } from '../../utils';
 import { type PathConfig, PathResolver, findConfigRoot } from './path-resolver';
 import { loadSharedConfigFiles } from '@smithy/shared-ini-file-loader';
diff --git a/src/lib/utils/__tests__/polling.test.ts b/src/lib/utils/__tests__/polling.test.ts
index c3440b669..581f6bc23 100644
--- a/src/lib/utils/__tests__/polling.test.ts
+++ b/src/lib/utils/__tests__/polling.test.ts
@@ -1,4 +1,5 @@
-import { PollExhaustedError, PollTimeoutError, isThrottlingError, poll } from '../polling.js';
+import { PollExhaustedError, PollTimeoutError } from '../../errors/types.js';
+import { isThrottlingError, poll } from '../polling.js';
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 
 /* eslint-disable @typescript-eslint/require-await */
diff --git a/src/lib/utils/index.ts b/src/lib/utils/index.ts
index 8902fca44..1ab339321 100644
--- a/src/lib/utils/index.ts
+++ b/src/lib/utils/index.ts
@@ -11,5 +11,5 @@ export {
 } from './subprocess';
 export { parseTimeString } from './time-parser';
 export { parseJsonRpcResponse } from './json-rpc';
-export { poll, isThrottlingError, PollTimeoutError, PollExhaustedError } from './polling';
+export { poll, isThrottlingError } from './polling';
 export { validateAgentSchema, validateProjectSchema } from './zod';
diff --git a/src/lib/utils/polling.ts b/src/lib/utils/polling.ts
index 3486e634f..012e02140 100644
--- a/src/lib/utils/polling.ts
+++ b/src/lib/utils/polling.ts
@@ -1,3 +1,5 @@
+import { PollExhaustedError, PollTimeoutError } from '../errors/types.js';
+
 /**
  * Shared polling/retry utility for async operations.
  */
@@ -23,20 +25,6 @@ export interface PollOptions<T> {
   onError?: (err: unknown) => 'retry' | 'abort';
 }
 
-export class PollTimeoutError extends Error {
-  constructor(timeoutMs: number, options?: { cause?: unknown }) {
-    super(`Polling timed out after ${timeoutMs}ms`, options);
-    this.name = 'PollTimeoutError';
-  }
-}
-
-export class PollExhaustedError extends Error {
-  constructor(maxAttempts: number, options?: { cause?: unknown }) {
-    super(`Polling exhausted after ${maxAttempts} attempts`, options);
-    this.name = 'PollExhaustedError';
-  }
-}
-
 export async function poll<T>(options: PollOptions<T>): Promise<T> {
   const {
     fn,