Build Claude Code-style intent understanding UX for Codexplain

[minsing-jin]

Goal

Build a Codexplain intent-understanding layer that makes Codex explanations feel closer to Claude Code UX: the system should infer what the user really wants, choose the right explanation form, and avoid dumping file-level or micro-step prose when a conceptual answer is needed.

Why

Current Codexplain improves rendering, width safety, row dividers, color, progress UI, and native TUI integration. The next UX gap is intent understanding: users ask in natural language, and the tool should reliably decide whether the answer needs architecture, diagnosis, comparison, workflow progress, risk review, next actions, or a short direct answer.

Requirements

• Detect user intent from one message and recent context: architecture, problem diagnosis, progress report, comparison, decision, implementation plan, research-style explanation, cause-effect report, and direct Q&A.
• Prefer capability/function-level explanations over file-by-file summaries unless the user explicitly asks for files.
• Use answer-first structure, then flow downward into evidence, reasoning, fixes, and next actions.
• Keep Korean responses Korean and default open-source docs/examples English.
• Route to existing Codexplain renderers: TLDR, wide-divider table, flow boxes, progress bar, risk panel, problem-diagnosis, cause-effect, Notion-style blocks, and checklist.
• Add a small explainable decision trace for debugging, without polluting normal answers.
• Preserve strict-output safety for JSON, code, diffs, logs, tests, patches, and commit messages.
• Provide project-local on/off controls and no global Codex mutation by default.

Acceptance Criteria

• codexplain shape chooses the intended renderer for at least 20 representative prompts across Korean and English.
• Architecture prompts produce concept/function-first diagrams, not file-first prose.
• Problem prompts produce answer-first diagnosis without forcing rigid labels when the language/context calls for a more natural flow.
• Long tables and diagrams remain width-safe under quality-check --width 88.
• A debug command shows why an intent/renderer was selected.
• cargo test, codexplain quality-check --width 88, and codexplain compat-check pass.

Notes

This should be implemented as a Codexplain UX layer, not as global Codex configuration. Native Codex TUI hooks should remain reversible through the project-local adapter.