Summary

Gemini CLI in non-interactive mode (which Untether uses via --output-format stream-json) converts all ASK_USER approval decisions to DENY, meaning write tools (file creation, editing) are blocked by default. The only way to enable write tools is --approval-mode=yolo.

Unlike Claude Code, Gemini CLI has no control channel for per-tool interactive approval — it's all-or-nothing.

Solution

Add an engine-aware "Approval mode" toggle to /config for Gemini, tied into the existing plan mode infrastructure:

• Home page: shows "Approval mode: read-only/full access" when engine is Gemini (alongside Claude's "Plan mode")
• Sub-page: "Read-only" (default, write tools blocked) / "Full access" (all tools approved via --approval-mode=yolo)
• Both Claude's plan mode and Gemini's approval mode use the same permission_mode field on EngineOverrides, sharing the config:pm callback prefix

Implementation

• engine_overrides.py: added PERMISSION_MODE_SUPPORTED_ENGINES = {"claude", "gemini"}
• config.py: made _page_home and _page_planmode engine-aware
• Gemini runner's build_args() already passes --approval-mode from permission_mode — no runner changes needed
• 9 new tests for Gemini approval mode UI

Files changed

• src/untether/telegram/engine_overrides.py
• src/untether/telegram/commands/config.py
• tests/test_config_command.py