Compatibility adapters for Lazycodex, Oh-my-codex, and cross-platform activation

[minsing-jin]

Goal

Make Codexplain adapt cleanly to external Codex harnesses and all major desktop platforms without forcing users into one shell, one launcher, or one Codex wrapper.

Scope

• Add compatibility adapters for Lazycodex and Oh-my-codex style harnesses.
• Detect whether Codex is being launched by stock Codex, Lazycodex, Oh-my-codex, a project-local shim, or another wrapper.
• Preserve strict reversibility: disabling or uninstalling Codexplain must remove only Codexplain-managed state.
• Support macOS, Linux, and Windows activation paths.
• Keep project-local mode as the default; global mode must remain explicit.

Platform Adaptation Requirements

macOS

• zsh auto-activation for project-local use.
• Optional status-bar/settings launcher.
• Preserve and restore existing user aliases/functions where possible.

Linux

• zsh/bash/fish-compatible activation strategy.
• Desktop launcher for settings UI where supported.
• No assumptions about Homebrew, npm global path, or shell framework.

Windows

• PowerShell activation script.
• cmd fallback script.
• Windows Terminal-friendly color behavior.
• Reversible project-local shim/wrapper strategy.

Harness Compatibility Requirements

• Lazycodex adapter: document expected launch paths, env vars, and wrapper order.
• Oh-my-codex adapter: detect harness-owned shims and avoid clobbering them.
• Provide an adapter contract so third-party harnesses can opt in:
• input stream/output stream expectations
• strict artifact bypass rules
• color mode negotiation
• TUI passthrough behavior
• project root discovery
• on/off/uninstall lifecycle hooks

Acceptance Criteria

• codexplain compat-check reports Lazycodex/Oh-my-codex adapter readiness.
• Project-local on/off works without modifying unrelated harness files.
• Windows/macOS/Linux activation paths are documented and tested where possible.
• Existing Codexplain behavior remains unchanged for stock Codex users.
• Uninstall removes only Codexplain-managed files, shell blocks, aliases, or launchers.
• README links to a docs page explaining harness and platform compatibility.

Validation Plan

• Add unit tests for adapter detection and lifecycle safety.
• Add shell-script snapshot tests for zsh/bash/fish/PowerShell activation outputs.
• Add a dry-run mode showing what would be modified before install/uninstall.
• Add manual test matrix for stock Codex, Lazycodex, Oh-my-codex, macOS, Linux, and Windows.

Notes

This should be implemented as an adapter layer, not as hard-coded assumptions about any single harness. Codexplain must remain a reversible presentation/activation layer rather than becoming a competing harness manager.