Unwrap fetch errors + show URL in Komodo probe result

The probe surfaced "unreachable: This operation was aborted" — technically
correct (an AbortController fired the fetch timeout) but useless for
diagnosing whether it's a wrong URL, blocked route, or firewall. Node's
fetch also hides real network causes (ECONNREFUSED, ENOTFOUND,
EHOSTUNREACH) under `.cause`, and the default message just says
"fetch failed".

describeFetchError() now unwraps AbortError to "timed out after 10000ms
dialing <url>" and pulls `.cause.code/.cause.message` for network
failures. KomodoPortResult gains a `url` field, always populated, so the
probe panel can surface the exact URL we dialed in a code block —
operators can then `curl` it from the container to confirm reachability.

komodoRestart benefits from the same unwrapping since it uses the same
komodoCall() transport.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/lib/server/integrations/komodo.ts

@@ -56,11 +56,13 @@ export async function komodoRestart(serverName: string): Promise<KomodoRestartRe
             break;
     }
 
+    const url = `${config.komodo.address.replace(/\/+$/, '')}/${path}`;
+
     let res: Response;
     try {
         res = await komodoCall(path, body);
     } catch (err) {
-        return { ok: false, kind: 'unreachable', message: (err as Error).message };
+        return { ok: false, kind: 'unreachable', message: describeFetchError(err, url) };
     }
     if (!res.ok) {
         return { ok: false, kind: 'http-error', message: `HTTP ${res.status}` };
@@ -94,6 +96,7 @@ export interface KomodoPortSuccess {
     ok: true;
     port: number;
     snippet: string;
+    url: string;
 }
 export interface KomodoPortFailureResult {
     ok: false;
@@ -101,6 +104,9 @@ export interface KomodoPortFailureResult {
     detail: string;
     httpStatus?: number;
     snippet?: string;
+    // URL we tried (or would have tried) — surfaced in the UI so operators
+    // can `curl` it from the container to verify reachability.
+    url?: string;
 }
 export type KomodoPortResult = KomodoPortSuccess | KomodoPortFailureResult;
 
@@ -111,6 +117,26 @@ function truncate(s: string): string {
     return s.slice(0, SNIPPET_LIMIT) + `\n… (${s.length - SNIPPET_LIMIT} more bytes)`;
 }
 
+/**
+ * Turn a Node/Undici fetch failure into something an operator can act on.
+ * The default `.message` for an aborted fetch is just "This operation was
+ * aborted" — useless. For network failures Node hides the real cause under
+ * `.cause` (e.g. `ECONNREFUSED`, `ENOTFOUND`, `EHOSTUNREACH`). Unwrap both
+ * and always include the URL we tried.
+ */
+function describeFetchError(err: unknown, url: string): string {
+    const e = err as (Error & { name?: string; cause?: unknown }) | undefined;
+    if (e?.name === 'AbortError') {
+        return `timed out after ${config.httpTimeoutMs}ms dialing ${url}`;
+    }
+    const cause = e?.cause as (Error & { code?: string }) | undefined;
+    if (cause && (cause.code || cause.message)) {
+        const code = cause.code ? `${cause.code}: ` : '';
+        return `${code}${cause.message ?? 'network error'} (dialing ${url})`;
+    }
+    return `${e?.message ?? String(err)} (dialing ${url})`;
+}
+
 function safeJsonStringify(value: unknown): string {
     try {
         return JSON.stringify(value, null, 2);
@@ -161,11 +187,13 @@ export async function komodoResolvePortDetailed(serverName: string): Promise<Kom
             break;
     }
 
+    const url = `${config.komodo.address.replace(/\/+$/, '')}/${path}`;
+
     let res: Response;
     try {
         res = await komodoCall(path, body);
     } catch (err) {
-        return { ok: false, reason: 'unreachable', detail: (err as Error).message };
+        return { ok: false, reason: 'unreachable', detail: describeFetchError(err, url), url };
     }
 
     // Read the body up front — we want the snippet even on non-2xx so the
@@ -178,7 +206,8 @@ export async function komodoResolvePortDetailed(serverName: string): Promise<Kom
             reason: 'http-error',
             detail: `HTTP ${res.status} ${res.statusText || ''}`.trim(),
             httpStatus: res.status,
-            snippet: truncate(rawText)
+            snippet: truncate(rawText),
+            url
         };
     }
 
@@ -191,7 +220,8 @@ export async function komodoResolvePortDetailed(serverName: string): Promise<Kom
             reason: 'unparseable',
             detail: `response body is not JSON: ${(err as Error).message}`,
             httpStatus: res.status,
-            snippet: truncate(rawText)
+            snippet: truncate(rawText),
+            url
         };
     }
 
@@ -203,10 +233,11 @@ export async function komodoResolvePortDetailed(serverName: string): Promise<Kom
             reason: 'no-udp-in-response',
             detail: 'parsed the response but no UDP port matched any known shape',
             httpStatus: res.status,
-            snippet
+            snippet,
+            url
         };
     }
-    return { ok: true, port, snippet };
+    return { ok: true, port, snippet, url };
 }
 
 /**

src/routes/servers/[name]/+page.svelte

@@ -16,6 +16,7 @@
         detail?: string;
         httpStatus?: number;
         snippet?: string;
+        url?: string;
     }
 
     interface Server {
@@ -212,6 +213,12 @@
                             {#if komodoProbe.httpStatus} · HTTP {komodoProbe.httpStatus}{/if}
                         </span>
                     </div>
+                    {#if komodoProbe.url}
+                        <div class="probe-url">
+                            <span class="k">tried</span>
+                            <code>{komodoProbe.url}</code>
+                        </div>
+                    {/if}
                     {#if komodoProbe.reason}
                         <div class="hint">{komodoFixHint(komodoProbe.reason, komodoProbe.httpStatus)}</div>
                     {/if}
@@ -505,6 +512,30 @@
     }
     .probe-detail strong { color: var(--spark-500); }
 
+    .probe-url {
+        display: flex;
+        align-items: baseline;
+        gap: 8px;
+        margin-top: 8px;
+        padding: 6px 12px;
+        background: var(--cherry-875);
+        border-radius: var(--r-sm);
+        border: 1px solid var(--cherry-700);
+        font-size: 11px;
+    }
+    .probe-url .k {
+        color: var(--ink-500);
+        font-family: var(--font-body);
+        font-size: 10px;
+        text-transform: uppercase;
+        letter-spacing: 1px;
+    }
+    .probe-url code {
+        color: var(--cream);
+        font-family: var(--font-mono);
+        word-break: break-all;
+    }
+
     .snippet-details {
         margin-top: 10px;
         font-family: var(--font-mono);