fix(core): a chunk timeout when processing llm stream (#16366)

packages/opencode/src/config/config.ts

@@ -972,6 +972,14 @@ export namespace Config {
             .describe(
               "Timeout in milliseconds for requests to this provider. Default is 300000 (5 minutes). Set to false to disable timeout.",
             ),
+          chunkTimeout: z
+            .number()
+            .int()
+            .positive()
+            .optional()
+            .describe(
+              "Timeout in milliseconds between streamed SSE chunks for this provider. If no chunk arrives within this window, the request is aborted.",
+            ),
         })
         .catchall(z.any())
         .optional(),

packages/opencode/src/provider/provider.ts

@@ -46,6 +46,8 @@ import { GoogleAuth } from "google-auth-library"
 import { ProviderTransform } from "./transform"
 import { Installation } from "../installation"
 
+const DEFAULT_CHUNK_TIMEOUT = 120_000
+
 export namespace Provider {
   const log = Log.create({ service: "provider" })
 
@@ -85,6 +87,54 @@ export namespace Provider {
     })
   }
 
+  function wrapSSE(res: Response, ms: number, ctl: AbortController) {
+    if (typeof ms !== "number" || ms <= 0) return res
+    if (!res.body) return res
+    if (!res.headers.get("content-type")?.includes("text/event-stream")) return res
+
+    const reader = res.body.getReader()
+    const body = new ReadableStream<Uint8Array>({
+      async pull(ctrl) {
+        const part = await new Promise<Awaited<ReturnType<typeof reader.read>>>((resolve, reject) => {
+          const id = setTimeout(() => {
+            const err = new Error("SSE read timed out")
+            ctl.abort(err)
+            void reader.cancel(err)
+            reject(err)
+          }, ms)
+
+          reader.read().then(
+            (part) => {
+              clearTimeout(id)
+              resolve(part)
+            },
+            (err) => {
+              clearTimeout(id)
+              reject(err)
+            },
+          )
+        })
+
+        if (part.done) {
+          ctrl.close()
+          return
+        }
+
+        ctrl.enqueue(part.value)
+      },
+      async cancel(reason) {
+        ctl.abort(reason)
+        await reader.cancel(reason)
+      },
+    })
+
+    return new Response(body, {
+      headers: new Headers(res.headers),
+      status: res.status,
+      statusText: res.statusText,
+    })
+  }
+
   const BUNDLED_PROVIDERS: Record<string, (options: any) => SDK> = {
     "@ai-sdk/amazon-bedrock": createAmazonBedrock,
     "@ai-sdk/anthropic": createAnthropic,
@@ -1092,21 +1142,23 @@ export namespace Provider {
       if (existing) return existing
 
       const customFetch = options["fetch"]
+      const chunkTimeout = options["chunkTimeout"] || DEFAULT_CHUNK_TIMEOUT
+      delete options["chunkTimeout"]
 
       options["fetch"] = async (input: any, init?: BunFetchRequestInit) => {
         // Preserve custom fetch if it exists, wrap it with timeout logic
         const fetchFn = customFetch ?? fetch
         const opts = init ?? {}
+        const chunkAbortCtl = typeof chunkTimeout === "number" && chunkTimeout > 0 ? new AbortController() : undefined
+        const signals: AbortSignal[] = []
 
-        if (options["timeout"] !== undefined && options["timeout"] !== null) {
-          const signals: AbortSignal[] = []
-          if (opts.signal) signals.push(opts.signal)
-          if (options["timeout"] !== false) signals.push(AbortSignal.timeout(options["timeout"]))
-
-          const combined = signals.length > 1 ? AbortSignal.any(signals) : signals[0]
+        if (opts.signal) signals.push(opts.signal)
+        if (chunkAbortCtl) signals.push(chunkAbortCtl.signal)
+        if (options["timeout"] !== undefined && options["timeout"] !== null && options["timeout"] !== false)
+          signals.push(AbortSignal.timeout(options["timeout"]))
 
-          opts.signal = combined
-        }
+        const combined = signals.length === 0 ? null : signals.length === 1 ? signals[0] : AbortSignal.any(signals)
+        if (combined) opts.signal = combined
 
         // Strip openai itemId metadata following what codex does
         // Codex uses #[serde(skip_serializing)] on id fields for all item types:
@@ -1126,11 +1178,14 @@ export namespace Provider {
           }
         }
 
-        return fetchFn(input, {
+        const res = await fetchFn(input, {
           ...opts,
           // @ts-ignore see here: https://github.com/oven-sh/bun/issues/16682
           timeout: false,
         })
+
+        if (!chunkAbortCtl) return res
+        return wrapSSE(res, chunkTimeout, chunkAbortCtl)
       }
 
       const bundledFn = BUNDLED_PROVIDERS[model.api.npm]

packages/opencode/test/provider/provider.test.ts

@@ -260,6 +260,7 @@ test("env variable takes precedence, config merges options", async () => {
             anthropic: {
               options: {
                 timeout: 60000,
+                chunkTimeout: 15000,
               },
             },
           },
@@ -277,6 +278,7 @@ test("env variable takes precedence, config merges options", async () => {
       expect(providers["anthropic"]).toBeDefined()
       // Config options should be merged
       expect(providers["anthropic"].options.timeout).toBe(60000)
+      expect(providers["anthropic"].options.chunkTimeout).toBe(15000)
     },
   })
 })

packages/web/src/content/docs/config.mdx

@@ -244,7 +244,7 @@ You can configure the providers and models you want to use in your OpenCode conf
 
 The `small_model` option configures a separate model for lightweight tasks like title generation. By default, OpenCode tries to use a cheaper model if one is available from your provider, otherwise it falls back to your main model.
 
-Provider options can include `timeout` and `setCacheKey`:
+Provider options can include `timeout`, `chunkTimeout`, and `setCacheKey`:
 
 ```json title="opencode.json"
 {
@@ -253,6 +253,7 @@ Provider options can include `timeout` and `setCacheKey`:
     "anthropic": {
       "options": {
         "timeout": 600000,
+        "chunkTimeout": 30000,
         "setCacheKey": true
       }
     }
@@ -261,6 +262,7 @@ Provider options can include `timeout` and `setCacheKey`:
 ```
 
 - `timeout` - Request timeout in milliseconds (default: 300000). Set to `false` to disable.
+- `chunkTimeout` - Timeout in milliseconds between streamed response chunks. If no chunk arrives in time, the request is aborted.
 - `setCacheKey` - Ensure a cache key is always set for designated provider.
 
 You can also configure [local models](/docs/models#local). [Learn more](/docs/models).