Module termination 

Shared termination/intent model for mecha10 dev’s interactive TUI screens.

Before this module existed, “what does this key mean” was answered independently by every screen that owned terminal input: the outer dev-mode loop (ops/interactive.rs) had its own is_dev_quit_key, the teleop sub-screen (ui/teleop.rs) had its own is_quit_all_key plus a separate zero-velocity x/Space branch, and three more call sites each registered their own ctrlc::set_handler. Because those handlers didn’t compose, the same physical key (x) meant two unrelated things depending on which screen happened to own input at the time: “stop the simulation” at the outer dev-mode menu, or “zero velocity, stay put” inside teleop. A user who pressed s (enter simulation, which auto-opens teleop) then x got the second meaning and nothing stopped - the reported bug this module fixes.

classify_key gives every screen the same answer for “what does this key mean”, and ScreenOutcome lets a nested screen (teleop) report what happened without needing to know about the outer loop’s own shutdown flag - the translation from “screen backed out” to “what that means for this caller” belongs to the caller (see ops/teleop.rs::enter_teleop_mode), not to the screen itself.

install_quit_signal replaces the four independent, copy-pasted ctrlc::set_handler registrations (ops/interactive.rs, ops/lifecycle.rs::run_watch_mode, handlers/logs.rs::follow_logs, plus what used to be ui/teleop.rs’s own Ctrl+C handling before it was folded into classify_key) with one shared helper.

Enums

ScreenOutcome

What a nested screen’s event loop did, for its caller to interpret. A screen that owns its own sub-context (e.g. TeleopUi) should never mutate the outer loop’s shutdown flag directly - it reports what happened here, and lets the caller (which knows how it was entered) decide what that means. See ops/teleop.rs::enter_teleop_mode, which interprets ReturnToParent differently depending on whether it was entered via 's' (simulation hand-off, so backing out means “stop the simulation and return to the dev-mode menu”) or 't' (standalone teleop, so backing out just closes the screen).

TerminationIntent

What a termination-shaped key (“stop the current thing” or “quit everything”) means.

Functions

classify_key

Classify a key event into a TerminationIntent, if it is one. Pure, dependency-free function so it’s unit testable without a live terminal/event loop.

install_quit_signal

Install a single process-wide Ctrl+C handler and return the shared “keep running” flag it clears on signal. Replaces the four independent, copy-pasted ctrlc::set_handler registrations that used to exist across ops/interactive.rs, ops/lifecycle.rs, and handlers/logs.rs.