fix(tui): route console output to log file to protect TUI display

[thomas-bw]

Issue for this PR

Fixes #48520

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

#31002 reports Ajv's unknown format "uint64" ignored warnings from Rust/schemars MCP schemas reaching the terminal via console.warn and polluting the TUI. PR #48331 fixes that specific source by disabling Ajv's logger through the MCP SDK's ClientOptions seam.

This PR is a complementary, systemic guardrail for the same problem: any library console.* output — Ajv today, plugin dependencies or anything else tomorrow — writes raw lines straight into the TUI's alternate screen and corrupts the display. A small ConsoleGuard is installed in every TUI entrypoint (tui, attach, run) and the server worker, redirecting console.debug/info/log/warn/error into the opencode log file while respecting the minimum log level (OPENCODE_LOG_LEVEL). Non-TUI entrypoints (serve, mcp list, ...) keep normal console behavior.

The two fixes are orthogonal: #48331 removes the Ajv warning at its source; this PR guarantees the TUI survives stray console output no matter where it comes from. Neither alone covers the full class of bug behind #31002.

How did you verify your code works?

• Two unit tests in packages/opencode/test/util/console-guard.test.ts: console output lands in the log file as a service=console line, and entries below the minimum level are suppressed while errors still get logged.
• bun test and bun typecheck pass in packages/opencode.
• Manual repro: start the TUI with an MCP server whose schemas contain uint32/uint64 formats. Before: Ajv warnings overwrite the display. After: they only appear in opencode.log.

Screenshots / recordings

Before:

After:

Log file:

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

Thanks for your contribution!

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Please:

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2. Add Fixes #<number> or Closes #<number> to this PR description

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[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Potential Related PRs Found:

1. fix(mcp): silence Ajv unknown format warnings from MCP tool schemas #48331 - fix(mcp): silence Ajv unknown format warnings from MCP tool schemas

   • This is explicitly mentioned in the current PR as a complementary fix targeting the same issue (MCP schema warnings: non-standard "format" values (uint32/uint64) from schemars pollute TUI #31002). The two PRs are orthogonal: fix(mcp): silence Ajv unknown format warnings from MCP tool schemas #48331 removes the Ajv warning at its source, while fix(tui): route console output to log file to protect TUI display #48517 provides a systemic guardrail for any console output.

2. fix(tui): contain stray stdio writes #43065 - fix(tui): contain stray stdio writes

   • This is related in spirit—both PRs address protecting the TUI display from unwanted output. However, fix(tui): contain stray stdio writes #43065 appears to focus on stdio writes specifically, while fix(tui): route console output to log file to protect TUI display #48517 tackles console output (console.log, console.warn, etc.).

Conclusion: These are related PRs addressing similar TUI protection concerns, but they're complementary fixes rather than duplicates. #48517 is distinct in focusing on console output redirection to log files with log-level filtering across all TUI entrypoints.