Replace brittle error text detection with isError flag

renderPerplexityResult was pattern-matching content text prefixes
to decide whether to render in error style. This was tightly coupled
to exact message strings in index.ts — a wording change would
silently break the error styling.

Set isError: true in details on every error return path in execute,
and check details.isError in the renderer instead.

src/index.ts

@@ -5,7 +5,7 @@ import { Type } from "@sinclair/typebox";
 import { registerPerplexityCommands } from "./commands/login.js";
 
 import { authenticate } from "./auth/login.js";
-import { clearToken } from "./auth/storage.js";
+
 import { formatForLLM } from "./search/format.js";
 import { searchPerplexity } from "./search/client.js";
 import { renderPerplexityCall } from "./render/call.js";
@@ -99,17 +99,29 @@ export default function (pi: ExtensionAPI) {
         if (error instanceof AuthError) {
           return {
             content: [{ type: "text", text: `Authentication failed: ${error.message}` }],
-            details: { sourceCount, queryMs },
+            details: { sourceCount, queryMs, isError: true },
           };
         }
 
         if (error instanceof SearchError) {
           if (error.code === "AUTH") {
-            await clearToken().catch(() => undefined);
+            // Do NOT clear the token here. The user must re-login explicitly via
+            // /perplexity-login --force. Clearing automatically would silently discard
+            // a token that may still be valid (e.g. a transient 401), and removes the
+            // user's ability to inspect or recover the cached credential themselves.
+            return {
+              content: [
+                {
+                  type: "text",
+                  text: `Perplexity authentication failed. Run /perplexity-login --force to re-authenticate.`,
+                },
+              ],
+              details: { sourceCount, queryMs, isError: true },
+            };
           }
           return {
             content: [{ type: "text", text: `Perplexity search failed: ${error.message}` }],
-            details: { sourceCount, queryMs },
+            details: { sourceCount, queryMs, isError: true },
           };
         }
 
@@ -120,7 +132,7 @@ export default function (pi: ExtensionAPI) {
               text: `Perplexity search failed: ${errorMessage(error)}`,
             },
           ],
-          details: { sourceCount, queryMs },
+          details: { sourceCount, queryMs, isError: true },
         };
       }
     },

src/render/result.ts

@@ -9,6 +9,7 @@ interface PerplexityResultDetails {
   uuid?: unknown;
   toolCallId?: unknown;
   error?: unknown;
+  isError?: unknown;
 }
 function extractTextContent(result: AgentToolResult<PerplexityResultDetails>): string | undefined {
   if (!Array.isArray(result?.content)) {
@@ -34,14 +35,6 @@ function extractTextContent(result: AgentToolResult<PerplexityResultDetails>): s
   return undefined;
 }
 
-function isErrorText(text: string | undefined): boolean {
-  if (!text) {
-    return false;
-  }
-
-  return text.startsWith("Authentication failed:") || text.startsWith("Perplexity search failed:");
-}
-
 export function renderPerplexityResult(
   result: AgentToolResult<PerplexityResultDetails>,
   options: ToolRenderResultOptions,
@@ -69,7 +62,7 @@ export function renderPerplexityResult(
     return new Text(theme.fg("error", `Perplexity error: ${error}`), 0, 0);
   }
 
-  if (isErrorText(contentText)) {
+  if (details.isError === true) {
     return new Text(theme.fg("error", truncate(contentText ?? "Perplexity request failed", 200)), 0, 0);
   }