The realtime effects loop in src/audio/realtime.rs was using
`eprintln!` to surface effect processing errors. That bypasses the
tracing subscriber and so the error never reaches the OTel collector
or the structured-log pipeline — invisible to operators in prod.
Switched to `tracing::error!` with the error captured as a structured
field, matching the rest of the stream server.
Why this was the only console-style call to fix:
The earlier audit reported 23 `console.log` instances across the
codebase, but most were in JSDoc/Markdown blocks or commented-out
lines. The actual production-code count, after stripping comments,
was zero on the frontend, zero in the backend API server (the
`fmt.Print*` calls live in CLI tools under cmd/ and are legitimate),
and one in the stream server (this fix). The rest of the Rust
println! calls are in load-test binaries and #[cfg(test)] blocks.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>