M27: Interaction modes and expertise-aware prompting

[bug-ops]

Summary

Implement expertise-level and interaction-mode system that adapts Zeph's behavior to the user's skill level and current task context. The agent should augment the developer, not replace them — different users need different interaction styles.

Motivation

Current system prompt is static and one-size-fits-all. This leads to:

• Over-explaining for experts (wastes tokens and time)
• Under-explaining for beginners (confusing, promotes vibecoding)
• No distinction between coding tasks, general Q&A, and automation

Design

Two orthogonal dimensions:

Expertise Level (beginner / intermediate / expert) — controls communication style:

• Beginner: explains every step, asks for understanding confirmation
• Intermediate: challenger mode, shows trade-offs, asks probing questions
• Expert: minimal commentary, executes efficiently, flags only genuine risks

Interaction Mode (assistant / coding / automation) — controls focus and persona:

• Assistant: general-purpose helper, conversational
• Coding: developer tool, code-centric, strict conventions
• Automation: task executor, minimal interaction, maximum throughput

Architecture

See .local/plan/m27-interaction-modes.md for full design doc.

Issues

• M27.1: Add ExpertiseLevel and InteractionMode config types #591 — Config types (ExpertiseLevel, InteractionMode enums)
• M27.2: Prompt templates module with persona/philosophy/guardrails blocks #592 — Prompt templates module
• M27.3: Refactor build_system_prompt() to use mode and expertise #593 — Refactor build_system_prompt()
• M27.4: Runtime mode switching via /mode and /expertise commands #594 — Runtime mode switching (/mode, /expertise commands)
• M27.5: CLI flags --mode and --expertise #595 — CLI flags (--mode, --expertise)
• M27.6: Update --init wizard for expertise and mode selection #596 — --init wizard update

Dependency Graph

#591 (config types)
 ├── #592 (prompt templates) ──┐
 ├── #595 (CLI flags)          │
 ├── #596 (--init wizard)      │
 └───────────────────────── #593 (refactor build_system_prompt)
                                └── #594 (runtime switching)