The earlier fix gated _resolve_use_tui, but the EARLY launcher
(_wants_tui_early) decides TUI from display.interface before cmd_chat
runs — so a `display.interface: tui` default still booted the Ink UI for
headless spawns (kanban workers), whose no-TTY bail-out exits 0 →
"protocol violation". Gate the early resolver on a real TTY: headless
stdio never boots the TUI regardless of config; explicit --tui still does.
An inherited HERMES_TUI=1 or a `display.interface: tui` config default sent
kanban workers into the Ink TUI, whose no-TTY bail-out exits 0 without doing
the task — every attempt ended in "protocol violation". Two layers:
- _default_spawn pins `--cli` (highest-precedence interface flag) and strips
HERMES_TUI from the child env (covers older builds on PATH).
- _resolve_use_tui gates ambient TUI prefs (env/config) behind a real TTY;
an explicit --tui still wins so the informative bail-out stays reachable.
Add `display.interface` config key so users can make the modern TUI the
default for bare `hermes` / `hermes chat` without exporting HERMES_TUI=1 in
every shell. Default stays "cli" to preserve current behavior.
Add a `--cli` flag (mirrors `--tui`) so an explicit invocation can force the
classic prompt_toolkit REPL even when `display.interface: tui` is configured.
Precedence (highest first): `--cli` > `--tui`/`HERMES_TUI=1` > config
`display.interface` > classic REPL. Two resolvers enforce it:
* `_resolve_use_tui(args)` — the args-aware resolver used by `cmd_chat`
and the Termux fast-TUI path (uses full load_config()).
* `_wants_tui_early(argv)` — a dependency-free early resolver used by
mouse-residue suppression and the Termux fast paths, which run before
argparse / hermes_cli.config are importable (minimal cached YAML read).
Both `--cli` and `--tui` are registered via `_inherited_flag`, so they are
carried across self-relaunch automatically.
- config: add display.interface ("cli" default), bump _config_version 25->26.
The generic missing-field migration + load_config() deep-merge seed the key
for existing configs; no bespoke migration block needed.
- docs: document --cli flag and display.interface in cli-commands.md and
the TUI user guide.
- tests: new test_default_interface_resolution.py covering resolver
precedence at every layer, early resolver edge cases (missing/garbage
config), parser flags, and relaunch inheritance.
