console.trace in fn.ts corrupts TUI display on schema validation failure #16841

Description

The console.trace("schema validation failure stack trace:") added in PR #16401 (src/util/fn.ts:9) writes raw text to stderr, which corrupts the TUI display. The terminal becomes garbled and requires a window resize to force a repaint.

This fires from src/server/routes/session.ts:575 through the Hono validator chain. It happens intermittently during normal usage (subagent dispatches, session operations).

This is what it looks like:

Steps to Reproduce

1. Use OpenCode TUI with subagents/tasks
2. Wait for a schema validation mismatch between the Hono route validator and the fn() service-level validator (seems to happen on session routes)
3. TUI display becomes garbled -- stack trace text bleeds into the terminal
4. Resizing the window forces a repaint and restores the display

Expected Behavior

Schema validation failures should be logged through the structured Log system (respecting log levels) rather than raw console.trace() to stderr, which conflicts with the TUI's terminal control.

Environment

• OpenCode version: latest (post-PR fix(core): log stack trace when schema validation fails #16401, March 6 2026)
• OS: macOS
• Terminal: standard terminal emulator

Suggested Fix

Replace console.trace() with the structured logger so it respects log levels and doesn't write raw text to the TUI-controlled terminal. The stack trace information is valuable for debugging but should go through the proper logging channel.