diff --git a/packages/opencode/src/plugin/copilot.ts b/packages/opencode/src/plugin/copilot.ts
index 17ce9debc7d..776b70fe91a 100644
--- a/packages/opencode/src/plugin/copilot.ts
+++ b/packages/opencode/src/plugin/copilot.ts
@@ -3,6 +3,9 @@ import { Installation } from "@/installation"
 import { iife } from "@/util/iife"
 
 const CLIENT_ID = "Ov23li8tweQw6odWQebz"
+// Add a small safety buffer when polling to avoid hitting the server
+// slightly too early due to clock skew / timer drift.
+const OAUTH_POLLING_SAFETY_MARGIN_MS = 3000 // 3 seconds
 
 function normalizeDomain(url: string) {
   return url.replace(/^https?:\/\//, "").replace(/\/$/, "")
@@ -204,6 +207,7 @@ export async function CopilotAuthPlugin(input: PluginInput): Promise<Hooks> {
                   const data = (await response.json()) as {
                     access_token?: string
                     error?: string
+                    interval?: number
                   }
 
                   if (data.access_token) {
@@ -230,13 +234,29 @@ export async function CopilotAuthPlugin(input: PluginInput): Promise<Hooks> {
                   }
 
                   if (data.error === "authorization_pending") {
-                    await new Promise((resolve) => setTimeout(resolve, deviceData.interval * 1000))
+                    await Bun.sleep(deviceData.interval * 1000 + OAUTH_POLLING_SAFETY_MARGIN_MS)
+                    continue
+                  }
+
+                  if (data.error === "slow_down") {
+                    // Based on the RFC spec, we must add 5 seconds to our current polling interval.
+                    // (See https://www.rfc-editor.org/rfc/rfc8628#section-3.5)
+                    let newInterval = (deviceData.interval + 5) * 1000
+
+                    // GitHub OAuth API may return the new interval in seconds in the response.
+                    // We should try to use that if provided with safety margin.
+                    const serverInterval = data.interval
+                    if (serverInterval && typeof serverInterval === 'number' && serverInterval > 0) {
+                      newInterval = serverInterval * 1000
+                    }
+
+                    await Bun.sleep(newInterval + OAUTH_POLLING_SAFETY_MARGIN_MS)
                     continue
                   }
 
                   if (data.error) return { type: "failed" as const }
 
-                  await new Promise((resolve) => setTimeout(resolve, deviceData.interval * 1000))
+                  await Bun.sleep(deviceData.interval * 1000 + OAUTH_POLLING_SAFETY_MARGIN_MS)
                   continue
                 }
               },