agent window: plain message when the endpoint wants a key

A 401/403 with an HTML error page (nginx) showed as "HTTP 401: 401
Authorization Required 401 Authorization Required nginx". Now: "The endpoint
wants an API key: enter it in ⚙" before one is set, "The endpoint refused
the API key (...)" after.

studio/agent.js

@@ -91,8 +91,13 @@
       var m = t;
       try { var x = JSON.parse(t); m = (x.error && (x.error.message || x.error)) || x.message || x.detail || t; } catch (e) { /* plain text */ }
       if (typeof m !== "string") m = JSON.stringify(m);
-      m = m.replace(/<[^>]+>/g, " ").replace(/\s+/g, " ").trim();
-      var hint = r.status === 401 || r.status === 403 ? " Check the API key (⚙)." : r.status === 404 ? " Check the endpoint: most servers want the URL ending in /v1." : "";
+      if (/^\s*</.test(m)) m = ""; // an HTML error page says no more than the status
+      m = m.replace(/\s+/g, " ").trim();
+      if (r.status === 401 || r.status === 403) {
+        return new Error(A.cfg.has_key ? "The endpoint refused the API key (HTTP " + r.status + (m ? ": " + clip(m, 200) : "") + "). Check it in ⚙."
+          : "The endpoint wants an API key: enter it in ⚙ (HTTP " + r.status + ").");
+      }
+      var hint = r.status === 404 ? " Check the endpoint: most servers want the URL ending in /v1." : "";
       return new Error("HTTP " + r.status + (m ? ": " + clip(m, 300) : "") + hint);
     });
   }

tools/agent_checks.py

@@ -121,7 +121,8 @@ def run(pg, objects, shot, check, can_set_key):
         settings()
         pg.locator("#agkey").fill("wrong-key")
         save()
-        check("401" in pg.locator("#agsetmsg").inner_text(), "a wrong key shows the endpoint's refusal: " + pg.locator("#agsetmsg").inner_text())
+        check("refused the API key" in pg.locator("#agsetmsg").inner_text() and "invalid api key" in pg.locator("#agsetmsg").inner_text(),
+              "a wrong key shows the endpoint's refusal: " + pg.locator("#agsetmsg").inner_text())
         check(pg.locator("#agwho .ag-off").count() == 1, "the status dot turns red")
         shot("agent-badkey.jpg")
         pg.locator("#agkey").fill("test-key")