chore: improve desktop renderer diagnostics

Serialize non-Error promise rejections so unhandled rejections print type/ctor/keys/JSON instead of the unreadable '[object Object]'. Also emit [server health] logs when a health poll returns unhealthy and when polling switches servers, so a red dot in the status popover comes with a logged URL and auth presence. Minor cosmetic: restore session-header StatusPopover import position after the earlier titlebar experiment.

packages/app/src/components/session/session-header.tsx

@@ -6,6 +6,7 @@ import { IconButton } from "@opencode-ai/ui/icon-button"
 import { Keybind } from "@opencode-ai/ui/keybind"
 import { Spinner } from "@opencode-ai/ui/spinner"
 import { showToast } from "@opencode-ai/ui/toast"
+import { StatusPopover } from "../status-popover"
 import { Tooltip, TooltipKeybind } from "@opencode-ai/ui/tooltip"
 import { getFilename } from "@opencode-ai/shared/util/path"
 import { createEffect, createMemo, For, onCleanup, onMount, Show } from "solid-js"
@@ -24,7 +25,6 @@ import { useSessionLayout } from "@/pages/session/session-layout"
 import { messageAgentColor } from "@/utils/agent"
 import { decode64 } from "@/utils/base64"
 import { Persist, persisted } from "@/utils/persist"
-import { StatusPopover } from "../status-popover"
 
 const OPEN_APPS = [
   "vscode",

packages/app/src/context/server.tsx

@@ -200,7 +200,20 @@ export const { use: useServer, provider: ServerProvider } = createSimpleContext(
 
     const isReady = createMemo(() => ready() && !!state.active)
 
-    const check = (conn: ServerConnection.Any) => checkServerHealth(conn.http).then((x) => x.healthy)
+    const check = (conn: ServerConnection.Any) =>
+      checkServerHealth(conn.http).then((x) => {
+        if (!x.healthy) {
+          // Loud: makes it trivial to see why a server shows red in the
+          // status popover / switcher. The dot only goes red when this
+          // returns false; otherwise undefined (gray) is emitted first.
+          console.warn("[server health] unhealthy", {
+            key: ServerConnection.key(conn),
+            url: conn.http.url,
+            hasAuth: !!(conn.http.username || conn.http.password),
+          })
+        }
+        return x.healthy
+      })
 
     createEffect(() => {
       const current_ = current()
@@ -211,6 +224,10 @@ export const { use: useServer, provider: ServerProvider } = createSimpleContext(
         return
       }
       setState("healthy", undefined)
+      console.log("[server health] start polling", {
+        key: ServerConnection.key(current_),
+        url: current_.http.url,
+      })
       onCleanup(startHealthPolling(current_))
     })
 

packages/desktop-electron/src/renderer/index.tsx

@@ -29,8 +29,36 @@ window.addEventListener("error", (event) => {
 
 window.addEventListener("unhandledrejection", (event) => {
   const reason = event.reason
-  const stack = reason instanceof Error ? reason.stack : null
-  console.error("[renderer unhandled rejection]", stack ?? reason)
+  // Log as much as possible: stack for Errors, JSON for plain objects with
+  // a fallback to a tagged shape so we never end up with just
+  // "[object Object]" in main.log.
+  if (reason instanceof Error) {
+    console.error("[renderer unhandled rejection]", reason.stack ?? reason.message ?? String(reason))
+    return
+  }
+  let serialized: string
+  try {
+    serialized = JSON.stringify(
+      reason,
+      (_key, value) => {
+        if (value instanceof Error) {
+          return { __error: true, name: value.name, message: value.message, stack: value.stack }
+        }
+        return value
+      },
+      2,
+    )
+  } catch {
+    serialized = String(reason)
+  }
+  console.error(
+    "[renderer unhandled rejection]",
+    `type=${typeof reason}`,
+    `ctor=${reason?.constructor?.name ?? "null"}`,
+    `keys=${reason && typeof reason === "object" ? Object.keys(reason).join(",") : "n/a"}`,
+    "value:",
+    serialized,
+  )
 })
 
 import {