building route handler adds an extra unneccesary rsc file

Link to the code that reproduces this issue

https://github.com/davecarlson/nextjs-route-handler-rsc-routes-repro

To Reproduce

To Reproduce

1. Clone https://github.com/davecarlson/nextjs-route-handler-rsc-routes-repro
2. npm install
3. npm run build
4. npm run verify:files

Current vs. Expected behavior

I see an extra file being created, meaning on large projects you can hit the Routes created per Deployment in 2x time.

I expect the number of handlers outputs to match the number of route handlers, and the extra .rsc .rsc.segment to not be created

For example, this gets created:
/api/[tenantId].rsc
/api/[tenantId]
/api/[tenantId]/items.rsc
/api/[tenantId]/items
/api/[tenantId]/items/[itemId].rsc
/api/[tenantId]/items/[itemId]

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 25.6.0: Fri Jul 31 19:19:08 PDT 2026; root:xnu-12377.161.14~5/RELEASE_ARM64_T6050
  Available memory (MB): 65536
  Available CPU cores: 18
Binaries:
  Node: 24.18.0
  npm: 11.16.0
  Yarn: N/A
  pnpm: N/A
Relevant Packages:
  next: 16.3.1 // Latest available version is detected (16.3.1).
  eslint-config-next: N/A
  react: 19.2.8
  react-dom: 19.2.8
  typescript: N/A
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Route Handlers, Dynamic Routes, Output

Which stage(s) are affected? (Select all that apply)

Build (Local), Vercel (Deployed)

Additional context

Checked with latest canary build - same issue exists.

I have a vercel build that fails due to hitting the limit : AhJzCWvPRMin8Lez85Q2CQQcqYn4

Clone the linked nextjs-route-handler-rsc-routes-repro repository and run npm install, npm run build, and npm run verify:files to confirm the extra outputs. Trace the build handling for dynamic route handlers and compare the generated files with the listed route handlers; done means the unnecessary .rsc and .rsc.segment outputs are no longer created.