diff --git a/actions/setup/js/pr_review_buffer.cjs b/actions/setup/js/pr_review_buffer.cjs
index 1aecb87540a..177a4f12e48 100644
--- a/actions/setup/js/pr_review_buffer.cjs
+++ b/actions/setup/js/pr_review_buffer.cjs
@@ -25,6 +25,7 @@ const { isStagedMode } = require("./safe_output_helpers.cjs");
 const { generateWorkflowCallIdMarker, matchesWorkflowId } = require("./generate_footer.cjs");
 const { attachExecutionState, fetchPullRequestReviewState } = require("./safe_output_execution_metadata.cjs");
 const { withRetry, RATE_LIMIT_RETRY_CONFIG, isTransientError, sleep } = require("./error_recovery.cjs");
+const { ERR_API } = require("./error_codes.cjs");
 
 const SUPERSEDE_REVIEW_MESSAGE = "Superseded by updated review from same workflow.";
 const MAX_SUPERSEDE_REVIEW_PAGES = 10;
@@ -126,7 +127,7 @@ function createReviewBuffer() {
       return await fetchPullRequestReviewState(github, repoParts, pullRequestNumber);
     } catch (error) {
       if (!isTransientError(error)) {
-        throw new Error(`Failed to capture ${phase} PR review state for #${pullRequestNumber}: ${getErrorMessage(error)} (non-transient)`, { cause: error });
+        throw new Error(`${ERR_API}: Failed to capture ${phase} PR review state for #${pullRequestNumber}: ${getErrorMessage(error)} (non-transient)`, { cause: error });
       }
       core.warning(`Failed to capture ${phase} PR review state for #${pullRequestNumber}: ${getErrorMessage(error)}. Continuing without execution-state metadata.`);
       return null;
diff --git a/actions/setup/js/set_issue_type.cjs b/actions/setup/js/set_issue_type.cjs
index 2468720bf3d..631bcf709d4 100644
--- a/actions/setup/js/set_issue_type.cjs
+++ b/actions/setup/js/set_issue_type.cjs
@@ -13,6 +13,7 @@ const { isStagedMode, checkRequiredFilter } = require("./safe_output_helpers.cjs
 const { createAuthenticatedGitHubClient } = require("./handler_auth.cjs");
 const { resolveSafeOutputIssueTarget } = require("./temporary_id.cjs");
 const { hasIssueIntentsRuntimeFeature, normalizeIssueIntentMetadata } = require("./issue_intents.cjs");
+const { ERR_VALIDATION } = require("./error_codes.cjs");
 
 /** @type {string} Safe output type handled by this module */
 const HANDLER_TYPE = "set_issue_type";
@@ -108,7 +109,7 @@ function toRestIssueIntentMetadata(intentMetadata) {
         restMetadata.confidence = "high";
         break;
       default:
-        throw new Error(`Invalid confidence ${JSON.stringify(intentMetadata.confidence)}. Expected one of: LOW, MEDIUM, HIGH.`);
+        throw new Error(`${ERR_VALIDATION}: Invalid confidence ${JSON.stringify(intentMetadata.confidence)}. Expected one of: LOW, MEDIUM, HIGH.`);
     }
   }
   return restMetadata;