[BUG] Streaming does not work for API routes

[vicb]

Describe the bug

See #102 (comment) (reported by @dandoen)

Streaming does not work for API routes (The whole response is sent at once)

Steps to reproduce

Use the code in the linked comment

Expected behavior

Streaming works

@opennextjs/cloudflare version

experimental branch as of Dec 6

Node.js version

22

Wrangler version

Custom - > 3.92

next info output

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 24.1.0: Thu Oct 10 21:00:32 PDT 2024; root:xnu-11215.41.3~2/RELEASE_ARM64_T6030
  Available memory (MB): 36864
  Available CPU cores: 12
Binaries:
  Node: 22.11.0
  npm: 10.9.0
  Yarn: N/A
  pnpm: 9.14.4
Relevant Packages:
  next: 14.2.11 // An outdated version detected (latest is 15.0.4), upgrade is highly recommended!
  eslint-config-next: 14.2.14
  react: 18.3.1
  react-dom: 18.3.1
  typescript: 5.5.4

Additional context

No response

[vicb]

@dandoen I was playing with your example this morning and noted something:

The stream route is statically rendered

If you force the route to be dynamic:

export async function GET(request: NextRequest) {
  headers().has("whatever");
  // ...
});

Then the route is dynamic:

And streaming works as expected.

Still next dev streams without having to force the route to be dynamic.

[dandoen]

Oh wow, good spot. Confirmed. Thx @vicb

[vicb]

We should keep this one opened while we figure out why it doesn't work for pre-rendered pages

[conico974]

This one can be closed, this is expected.
If the route is ISR/SSG, the result are retrieved from the incremental cache and sent right away (it's the same behavior in next/start )
next dev is specific and doesn't use the incremental cache, that's why it "worked" there