diff --git a/packages/opencode/src/session/retry.ts b/packages/opencode/src/session/retry.ts
index 463bc27a95db..48d119b85c9f 100644
--- a/packages/opencode/src/session/retry.ts
+++ b/packages/opencode/src/session/retry.ts
@@ -31,6 +31,14 @@ function cap(ms: number) {
   return Math.min(ms, RETRY_MAX_DELAY)
 }
 
+function backoff(attempt: number) {
+  return cap(Math.min(RETRY_INITIAL_DELAY * Math.pow(RETRY_BACKOFF_FACTOR, attempt - 1), RETRY_MAX_DELAY_NO_HEADERS))
+}
+
+function isDelayHint(value: number) {
+  return Number.isFinite(value) && value >= 0
+}
+
 export function delay(attempt: number, error?: MessageV2.APIError) {
   if (error) {
     const headers = error.data.responseHeaders
@@ -38,15 +46,13 @@ export function delay(attempt: number, error?: MessageV2.APIError) {
       const retryAfterMs = headers["retry-after-ms"]
       if (retryAfterMs) {
         const parsedMs = Number.parseFloat(retryAfterMs)
-        if (!Number.isNaN(parsedMs)) {
-          return cap(parsedMs)
-        }
+        if (isDelayHint(parsedMs)) return cap(parsedMs)
       }
 
       const retryAfter = headers["retry-after"]
       if (retryAfter) {
         const parsedSeconds = Number.parseFloat(retryAfter)
-        if (!Number.isNaN(parsedSeconds)) {
+        if (isDelayHint(parsedSeconds)) {
           // convert seconds to milliseconds
           return cap(Math.ceil(parsedSeconds * 1000))
         }
@@ -57,11 +63,11 @@ export function delay(attempt: number, error?: MessageV2.APIError) {
         }
       }
 
-      return cap(RETRY_INITIAL_DELAY * Math.pow(RETRY_BACKOFF_FACTOR, attempt - 1))
+      return backoff(attempt)
     }
   }
 
-  return cap(Math.min(RETRY_INITIAL_DELAY * Math.pow(RETRY_BACKOFF_FACTOR, attempt - 1), RETRY_MAX_DELAY_NO_HEADERS))
+  return backoff(attempt)
 }
 
 export function retryable(error: Err, provider: string) {
diff --git a/packages/opencode/test/session/retry.test.ts b/packages/opencode/test/session/retry.test.ts
index 22ff6cde811d..0c788326fdf4 100644
--- a/packages/opencode/test/session/retry.test.ts
+++ b/packages/opencode/test/session/retry.test.ts
@@ -37,6 +37,12 @@ describe("session.retry.delay", () => {
     expect(delays).toStrictEqual([2000, 4000, 8000, 16000, 30000, 30000, 30000, 30000, 30000, 30000])
   })
 
+  test("caps delay at 30 seconds when headers omit retry hints", () => {
+    const error = apiError({ date: new Date().toUTCString() })
+    const delays = Array.from({ length: 10 }, (_, index) => SessionRetry.delay(index + 1, error))
+    expect(delays).toStrictEqual([2000, 4000, 8000, 16000, 30000, 30000, 30000, 30000, 30000, 30000])
+  })
+
   test("prefers retry-after-ms when shorter than exponential", () => {
     const error = apiError({ "retry-after-ms": "1500" })
     expect(SessionRetry.delay(4, error)).toBe(1500)
@@ -60,6 +66,11 @@ describe("session.retry.delay", () => {
     expect(SessionRetry.delay(1, error)).toBe(2000)
   })
 
+  test("ignores negative retry hints", () => {
+    expect(SessionRetry.delay(1, apiError({ "retry-after-ms": "-1" }))).toBe(2000)
+    expect(SessionRetry.delay(2, apiError({ "retry-after": "-1" }))).toBe(4000)
+  })
+
   test("ignores malformed date retry hints", () => {
     const error = apiError({ "retry-after": "Invalid Date String" })
     expect(SessionRetry.delay(1, error)).toBe(2000)