Avoid rescanning HTML challenge pages during error formatting

chris-yyau · steipete · commit 59caf03d6783 · 2026-04-16T12:47:12.000-07:00
The HTML challenge fix already keeps standalone CDN block pages out of the DNS transport path. This follow-up caches the HTML classification so status-prefixed non-HTML failures do not pay for the same scan twice and the control flow stays simpler.

Constraint: Keep behavior identical for both status-prefixed HTML pages and standalone HTML challenge pages
Rejected: Inline the helper into the status branch only | would duplicate the standalone HTML branch logic
Confidence: high
Scope-risk: narrow
Directive: If this formatter grows more branches, keep a single HTML classification result and reuse it through the decision tree
Tested: oxfmt --check src/shared/assistant-error-format.ts
Tested: node scripts/test-projects.mjs src/agents/pi-embedded-helpers.formatassistanterrortext.test.ts src/agents/pi-embedded-helpers.isbillingerrormessage.test.ts
diff --git a/src/shared/assistant-error-format.ts b/src/shared/assistant-error-format.ts
@@ -182,11 +182,12 @@ export function formatRawAssistantErrorForUi(raw?: string): string {
   }
 
   const leadingStatus = extractLeadingHttpStatus(trimmed);
-  if (leadingStatus && isCloudflareOrHtmlErrorPage(trimmed)) {
+  const isHtmlChallenge = isCloudflareOrHtmlErrorPage(trimmed);
+  if (leadingStatus && isHtmlChallenge) {
     return `The AI service is temporarily unavailable (HTTP ${leadingStatus.code}). Please try again in a moment.`;
   }
 
-  if (isCloudflareOrHtmlErrorPage(trimmed)) {
+  if (isHtmlChallenge) {
     return (
       "The provider returned an HTML error page instead of an API response. " +
       "This usually means a CDN or gateway (e.g. Cloudflare) blocked the request. " +

Original file line number	Diff line number	Diff line change
`@@ -182,11 +182,12 @@ export function formatRawAssistantErrorForUi(raw?: string): string {`
`182`	`182`	`}`
`183`	`183`
`184`	`184`	`const leadingStatus = extractLeadingHttpStatus(trimmed);`
`185`		`- if (leadingStatus && isCloudflareOrHtmlErrorPage(trimmed)) {`
	`185`	`+ const isHtmlChallenge = isCloudflareOrHtmlErrorPage(trimmed);`
	`186`	`+ if (leadingStatus && isHtmlChallenge) {`
`186`	`187`	return `The AI service is temporarily unavailable (HTTP ${leadingStatus.code}). Please try again in a moment.`;
`187`	`188`	`}`
`188`	`189`
`189`		`- if (isCloudflareOrHtmlErrorPage(trimmed)) {`
	`190`	`+ if (isHtmlChallenge) {`
`190`	`191`	`return (`
`191`	`192`	`"The provider returned an HTML error page instead of an API response. " +`
`192`	`193`	`"This usually means a CDN or gateway (e.g. Cloudflare) blocked the request. " +`