fix: Eliminate Turbopack/NFT build warning

[Delqhi]

Problem

The Next.js 16.2.6 build produces a persistent Turbopack/NFT warning:

Turbopack build encountered 1 warnings:
./next.config.mjs
Encountered unexpected file in NFT list
A file was traced that indicates that the whole project was traced unintentionally.

This happens because API routes (e.g., app/api/sin/orchestrator/stream/route.ts) use node:child_process (spawn/execFile), which causes Turbopack's Node File Tracing (NFT) to conservatively include the entire project directory in the standalone output.

While the build succeeds, this warning indicates the bundle is larger than necessary and may include files that shouldn't be in the production server.

Goal

Eliminate the NFT warning by ensuring all filesystem operations are statically scoped to specific subdirectories, or by suppressing the trace for dynamic paths.

Acceptance Criteria

• pnpm build produces zero warnings
• The standalone output (.next/standalone/) does not include unnecessary project files
• Build time is not significantly increased
• Alternative: Document the warning as a known upstream issue if no fix is possible

Files to investigate / modify

Files to investigate

app/api/sin/orchestrator/stream/route.ts    # Uses spawn() — potential NFT trigger
lib/sin/run.ts                            # Uses execFile() with BIN path
lib/chat-history.ts                       # Uses path.join(process.cwd(), ...)
lib/audit.ts                              # Uses path.join(process.cwd(), ...)
lib/shares.ts                             # Uses path.join(process.cwd(), ...)
lib/tokens.ts                             # Uses path.join(process.cwd(), ...)
lib/workspaces.ts                         # Uses path.join(process.cwd(), ...)
next.config.mjs                           # May need turbopack.ignore or outputFileTracingExcludes

Technical Notes

• Next.js 16.2.6 Turbopack has a known limitation with dynamic fs operations in server code
• The NFT tracer analyzes fs calls at build time to determine what files to include in the standalone output
• When it sees unbounded dynamic paths (like process.cwd() or path.join with dynamic variables), it includes the entire project
• Potential fixes:
  1. Use path.join(process.cwd(), 'data', filename) instead of path.join(process.cwd(), filename) — Already done
  2. Add turbopack.ignore in next.config.mjs to exclude specific paths from tracing
  3. Move the dynamic fs operations to a separate file that is imported dynamically (import())
  4. Use outputFileTracingExcludes in next.config.mjs to exclude directories
  5. Wait for upstream Next.js fix (may be resolved in 16.3+)
• The warning specifically traces to next.config.mjs → app/api/sin/orchestrator/stream/route.ts, suggesting the spawn call is the root cause

Related

• AGENTS.md §5.7: Build warnings should be eliminated before shipping
• app/api/sin/orchestrator/stream/route.ts: Uses spawn(BIN, ['orchestrator-run', task])
• lib/sin/run.ts: Uses execFile(BIN, ...) — BIN is process.env.SIN_CODE_BIN || 'sin-code'
• Next.js upstream issue: https://github.com/vercel/next.js/issues/ (search for "Turbopack NFT unexpected file")

[Delqhi]

Partially fixed and merged to main via #58 (commit 30de716).

What was done:

• Wrapped 30+ path.join(process.cwd(), ...) and process.cwd() calls in lazy-getter functions
• Added /*turbopackIgnore: true*/ and // @turbopack-disable-next-line comments
• Added outputFileTracingExcludes in next.config.mjs
• Removed .next from .dockerignore so fresh builds are included

Result: 3 warnings → 1 warning. The remaining warning is a known Turbopack 16.2.6 limitation (the NFT tracer doesn't fully respect ignore comments inside arrow function closures in design-edit/route.ts).

Follow-up: See new issue for upgrading to Next.js 16.3+ where the issue is reportedly resolved.