diff --git a/src/core/abTestExecutionRole.tsx b/src/core/abTestExecutionRole.tsx
index 721f4d026..458db3a78 100644
--- a/src/core/abTestExecutionRole.tsx
+++ b/src/core/abTestExecutionRole.tsx
@@ -7,6 +7,7 @@ import {
   type IAMClient,
 } from "@aws-sdk/client-iam";
 import { createHash } from "node:crypto";
+import { parseArn, resourceNameFromArn } from "./arn";
 
 const AB_TEST_POLICY_NAME = "ABTestExecutionPolicy";
 
@@ -16,13 +17,8 @@ export function abTestExecutionRoleName(testName: string): string {
   return `${base.slice(0, 55)}-${hash}`;
 }
 
-export function roleNameFromArn(roleArn: string): string {
-  const parts = roleArn.split("/");
-  return parts[parts.length - 1] ?? roleArn;
-}
-
 export function accountIdFromArn(arn: string): string {
-  const accountId = arn.split(":")[4];
+  const accountId = parseArn(arn)?.account;
   if (!accountId) throw new Error(`could not extract account id from ARN: ${arn}`);
   return accountId;
 }
@@ -139,7 +135,7 @@ export async function provisionAbTestRole(
 }
 
 export async function deleteAbTestRole(iam: IAMClient, roleArn: string): Promise<void> {
-  const roleName = roleNameFromArn(roleArn);
+  const roleName = resourceNameFromArn(roleArn);
   try {
     await iam.send(
       new DeleteRolePolicyCommand({ RoleName: roleName, PolicyName: AB_TEST_POLICY_NAME }),
diff --git a/src/core/eval.tsx b/src/core/eval.tsx
index 34ad58774..bf9080d51 100644
--- a/src/core/eval.tsx
+++ b/src/core/eval.tsx
@@ -172,10 +172,10 @@ import {
   grantOnlineEvalScope,
   isManagedOnlineEvalRole,
   revokeOnlineEvalScope,
-  roleNameFromArn,
   scopePolicyName,
 } from "./onlineEvalExecutionRole";
 import { accountIdFromArn, deleteAbTestRole, provisionAbTestRole } from "./abTestExecutionRole";
+import { resourceNameFromArn } from "./arn";
 import { harnessRuntimeFromResponse } from "./harness";
 
 const DEFAULT_INGESTION_WAIT_MS = 180_000;
@@ -1289,7 +1289,7 @@ export class EvalClient implements CoreEvalClient {
         options.region,
         newLogGroups,
         kmsKeys,
-        roleNameFromArn(roleArn!),
+        resourceNameFromArn(roleArn!),
       );
       const oldPolicyName = scopePolicyName(
         executionPolicy(
@@ -1312,7 +1312,7 @@ export class EvalClient implements CoreEvalClient {
       if (newPolicyName !== oldPolicyName) {
         const revoked = await revokeOnlineEvalScope(
           iam,
-          roleNameFromArn(managedRoleArn),
+          resourceNameFromArn(managedRoleArn),
           oldPolicyName,
         ).catch(() => false);
         // The config is already correct; the role just still grants a data
diff --git a/src/core/executionRole.tsx b/src/core/executionRole.tsx
index 0a7581019..e93bec34a 100644
--- a/src/core/executionRole.tsx
+++ b/src/core/executionRole.tsx
@@ -4,6 +4,7 @@ import {
   PutRolePolicyCommand,
   type IAMClient,
 } from "@aws-sdk/client-iam";
+import { parseArn } from "./arn";
 
 // Default harness execution role provisioning.
 //
@@ -223,7 +224,7 @@ function executionPolicy(region: string, accountId: string, harnessName: string)
 // (arn:aws:iam::<account>:role/<name>), which saves an STS lookup: the account
 // only becomes relevant once we hold the role's ARN anyway.
 function accountIdFromRoleArn(arn: string): string {
-  const accountId = arn.split(":")[4];
+  const accountId = parseArn(arn)?.account;
   if (!accountId) {
     throw new Error(`Cannot extract an account id from role ARN "${arn}"`);
   }
diff --git a/src/core/onlineEvalExecutionRole.tsx b/src/core/onlineEvalExecutionRole.tsx
index 4f15beb01..e02a6f40a 100644
--- a/src/core/onlineEvalExecutionRole.tsx
+++ b/src/core/onlineEvalExecutionRole.tsx
@@ -6,6 +6,7 @@ import {
   PutRolePolicyCommand,
   type IAMClient,
 } from "@aws-sdk/client-iam";
+import { parseArn, resourceNameFromArn } from "./arn";
 
 // Default online-evaluation execution role provisioning, mirroring
 // core/executionRole.tsx's pattern for harnesses: CreateOnlineEvaluationConfig
@@ -49,15 +50,11 @@ function truncatedRolePrefix(configName: string): string {
   return `${ROLE_NAME_PREFIX}${configName.slice(0, room)}-`;
 }
 
-export function roleNameFromArn(roleArn: string): string {
-  return roleArn.slice(roleArn.lastIndexOf("/") + 1);
-}
-
 // isManagedOnlineEvalRole recognises the CLI's default role for a config. Roles
 // created before the hash moved off Bun.hash carry a different suffix, so a
 // truncated name is matched on its prefix rather than recomputed.
 export function isManagedOnlineEvalRole(roleArn: string, configName: string): boolean {
-  const roleName = roleNameFromArn(roleArn);
+  const roleName = resourceNameFromArn(roleArn);
   const full = `${ROLE_NAME_PREFIX}${configName}`;
   if (full.length <= ROLE_NAME_MAX) return roleName === full;
   return roleName.startsWith(truncatedRolePrefix(configName));
@@ -188,7 +185,7 @@ export function executionPolicy(
 }
 
 export function accountIdFromRoleArn(arn: string): string {
-  const accountId = arn.split(":")[4];
+  const accountId = parseArn(arn)?.account;
   if (!accountId) {
     throw new Error(`Cannot extract an account id from role ARN "${arn}"`);
   }
diff --git a/src/core/policy.tsx b/src/core/policy.tsx
index efbf663a5..9003eafb3 100644
--- a/src/core/policy.tsx
+++ b/src/core/policy.tsx
@@ -22,6 +22,7 @@ import type {
 import type { Logger } from "../logging";
 import type { ProgressEvent } from "../tui/progress";
 import type { AwsClients, CoreOptions } from "./types";
+import { resourceNameFromArn } from "./arn";
 import { toClientConfig } from "./utils";
 
 export type PolicyGenerationWait = {
@@ -32,10 +33,6 @@ export type PolicyGenerationWait = {
 
 const DEFAULT_WAIT: PolicyGenerationWait = { maxWaitTime: 60, minDelay: 2, maxDelay: 5 };
 
-function resourceIdFromArn(value: string): string {
-  return value.startsWith("arn:") ? value.slice(value.lastIndexOf("/") + 1) : value;
-}
-
 export class PolicyClient implements CorePolicyClient {
   constructor(
     private readonly clients: AwsClients,
@@ -49,7 +46,7 @@ export class PolicyClient implements CorePolicyClient {
     signal?: AbortSignal,
   ): AsyncGenerator<ProgressEvent, PolicyGenerationResult> {
     const control = this.clients.control(toClientConfig(options));
-    const gatewayId = resourceIdFromArn(input.gatewayId);
+    const gatewayId = resourceNameFromArn(input.gatewayId);
 
     yield { type: "step", message: `Resolving gateway ${gatewayId}` };
     const gateway = await control.send(new GetGatewayCommand({ gatewayIdentifier: gatewayId }), {
@@ -62,7 +59,7 @@ export class PolicyClient implements CorePolicyClient {
         `gateway '${gatewayId}' has no Policy Engine attached; pass --policy-engine-id`,
       );
     }
-    const policyEngineId = resourceIdFromArn(engine);
+    const policyEngineId = resourceNameFromArn(engine);
 
     yield { type: "step", message: `Starting policy generation ${input.name}` };
     const started = await control.send(
diff --git a/src/core/project/bedrockAgentImport/baseTranslator.ts b/src/core/project/bedrockAgentImport/baseTranslator.ts
index 7b108e3f8..3cb133edb 100644
--- a/src/core/project/bedrockAgentImport/baseTranslator.ts
+++ b/src/core/project/bedrockAgentImport/baseTranslator.ts
@@ -1,3 +1,4 @@
+import { regionFromArn, resourceNameFromArn } from "../../arn";
 import { IMPORT_NOTES_FILE, renderImportNotes } from "./importNotes";
 import { generateImportPyproject } from "./pyproject";
 import type {
@@ -220,7 +221,7 @@ def ${pythonIdentifier(fn.name)}(${parameters}) -> str:
  */
 export function providerFromModelArn(foundationModel: string): string | undefined {
   if (!foundationModel.startsWith("arn:")) return undefined;
-  const resource = foundationModel.split("/").pop() ?? "";
+  const resource = resourceNameFromArn(foundationModel);
   const provider = resource.split(".")[0];
   return provider && provider !== resource ? provider.toLowerCase() : undefined;
 }
@@ -230,7 +231,7 @@ export function providerFromModelArn(foundationModel: string): string | undefine
  * its ARN and fall back to the agent's region only when the ARN was unavailable.
  */
 export function knowledgeBaseRegion(knowledgeBase: { arn?: string }, agentRegion: string): string {
-  return knowledgeBase.arn?.split(":")[3] || agentRegion;
+  return regionFromArn(knowledgeBase.arn ?? "") ?? agentRegion;
 }
 
 /** The root snapshot followed by every collaborator reachable from it, depth-first. */
diff --git a/src/core/project/templates/export.ts b/src/core/project/templates/export.ts
index fb0c37d0e..d42c29e5b 100644
--- a/src/core/project/templates/export.ts
+++ b/src/core/project/templates/export.ts
@@ -19,6 +19,7 @@ import type { Memory } from "../../../projectSchemas/memory";
 import type { EnvLocalEntry } from "../../../handlers/project/types";
 import { InputValidationError } from "../../../errors/errors";
 import { toPythonPackageName } from "../fsUtils";
+import { resourceNameFromArn } from "../../arn";
 
 type ProjectSpec = z.infer<typeof ProjectSpecSchema>;
 
@@ -768,9 +769,7 @@ function resolveSkills(
   for (const skill of gitSkillSources) {
     const reference = skill.auth?.credentialArn ?? skill.auth?.credentialName;
     if (!reference) continue;
-    const name = reference.includes("/")
-      ? reference.slice(reference.lastIndexOf("/") + 1)
-      : reference;
+    const name = resourceNameFromArn(reference);
     if (seenGitCredentials.has(name)) continue;
     seenGitCredentials.add(name);
     if (!credentials.some((c) => c.name === name)) {