Provider Comparison

Capability matrix

Feature	Codex	Pi	Copilot	Fake
Text input	✅	✅	✅	✅
Local images	✅	✅	❌	✅
Image URLs	✅	❌	❌	✅
Skills	✅	✅	❌	✅
Model switching	✅	✅	✅	✅
Reasoning levels	✅	✅	❌	✅
Compaction	✅	✅	❌	✅
Session archive	✅	✅	✅	✅
Interrupt	✅	✅	✅	✅
Approvals (command)	✅	❌	✅	✅
Approvals (file)	✅	❌	❌	✅
Approvals (permissions)	✅	❌	❌	✅
Filesystem	Host	Host	Host	Host
Terminal	Host	Host	Host	Host
Browser	Host	Host	Host	Host

Architecture differences

	Codex	Pi	Copilot	Fake
Runtime	Shells out to codex CLI	In-process TypeScript SDK	Shells out to Copilot CLI	In-process harness
Session storage	Codex .codex directory	~/.pi/agent/sessions/	Copilot SDK managed	In-memory / ephemeral
Auth	Codex CLI auth	pi /login	GitHub CLI auth	None
Config	~/.sidemesh/config.json	~/.sidemesh/config.json + ~/.pi/agent/	GitHub CLI config	Env vars only

When to use which

• Use Codex when you want the richest tool ecosystem and full approval gating
• Use Pi when you want in-process execution, native compaction, and thinking-level control
• Use Copilot when you are already committed to GitHub Copilot and want mobile access
• Use Fake for automated testing, screenshots, and reproducing specific UI states