Merge origin/master (v0.5.81) into gitea/new_feature

Resolve conflicts:
- streamingHandler.js: merge buildStreamErrorBytes onAbortTerminal + local shouldPersistRequestDetail & streamStatusForContent
- capabilities.js: preserve server-injected user-asserted caps and models.dev catalog lookup; wire CommandCode /alpha/generate caps inside resolve()
- commandcode.js (services/usage): adopt upstream whoami + billing credits/subscriptions with 5h/weekly rate windows and plan caps
- openai-to-commandcode.js: merge toNativeImageBlock (data-URI & http(s) support) and assistant reasoning_content preservation
- commandcode-to-openai.js: adopt upstream mid-stream error throw for clean retry and abortion
- tests: sync commandcode test suite and exclude .next from vitest config

open-sse/services/accountFallback.js

@@ -29,7 +29,7 @@ export function checkFallbackError(status, errorText, backoffLevel = 0) {
     // Request-scoped rule: the request body itself is at fault — no cooldown,
     // no account lock. Caller must stop rotating and surface the error.
     if (rule.requestScoped && lowerError && lowerError.includes(rule.text)) {
-      return { shouldFallback: false, requestScoped: true, cooldownMs: 0 };
+      return { shouldFallback: false, cooldownMs: 0 };
     }
 
     // Text-based rule: match substring in error message
@@ -51,6 +51,20 @@ export function checkFallbackError(status, errorText, backoffLevel = 0) {
     }
   }
 
+  // Request-scoped client errors that matched no rule above: a 400 caused by the
+  // request itself (context overflow, malformed body, unsupported parameter) says
+  // nothing about the credential, so cooling the account down only removes a
+  // healthy connection from rotation. With a single connection it is worse: every
+  // later request in the window fails with a copy of this very error
+  // ("all 1 accounts locked for <model> | lastError=[400]: ..."), which hides the
+  // real cause from the caller and makes unrelated sessions look like they hit the
+  // same limit. Hand the upstream error back for this request instead.
+  // Account-scoped statuses keep their rules above (401/402/403/404/429), and the
+  // text rules still win for rate-limit / quota / capacity wording.
+  if (status >= 400 && status < 500 && status !== 401 && status !== 402 && status !== 403 && status !== 429) {
+    return { shouldFallback: false, cooldownMs: 0 };
+  }
+
   // Default: transient cooldown for any unmatched error
   return { shouldFallback: true, cooldownMs: TRANSIENT_COOLDOWN_MS };
 }