fix(exit): give system, theme and apps the menu split the rest already had

[MCamner]

Closes the last open finding from the P2 operator inventory, and writes down the contract the interactive entrypoints had been guessing at.

The contract

• a valid interactive menu with no terminal available renders at most once and exits 0
• an operation given arguments propagates its real status
• an invalid argument is 2
• repos keeps 1 as a documented exception — it asks for a terminal-dependent repo picker while also offering headless subcommands, so "there was no terminal" is the true answer there

Measured

All eleven interactive entrypoints, run headless, ended at their own prompt on EOF. Three answered differently:

git release shortcuts tools workflows dev hal performance   exit 0
system theme apps                                           exit 1

apps is a third outlier the first sweep missed — it was read as an AI command and excluded on cost. Without a question it runs hal-terminal-guide.sh, an interactive guide.

Separately, theme did not meet the third point: mq-zsh-theme-switcher.sh exited 1 for an unknown command word, for apply with no variant, and for a variant that does not exist. 1 reads as "the theme could not be applied" rather than "that is not a theme". system bogusverb already answered 2, which settled it.

After

all ten local menus, headless and on a pty   exit 0, prompt drawn once
mqlaunch system check / theme current        exit 0
mqlaunch system bogusverb                    exit 2
mqlaunch theme bogusverb                     exit 2
mqlaunch theme apply                         exit 2
mqlaunch theme apply no-such-variant         exit 2
mqlaunch repos                               exit 1  (documented exception)
missing theme file                           exit 1  (runtime, not usage)

The structural gate could not have caught this, then failed for the wrong reason

Step 7 of tests/delegated-exit-code-smoke.sh flags a branch only when it both invokes a $BASE_DIR script and ends in a bare return 0. theme invokes no script, and the mixed shape is not what the pattern describes. Applying the fix then made step 7 fail, because system and apps do call scripts and now hold a deliberate return 0.

I did not reword the rule until it passed. Step 7 carries a named exception list and honours an entry only when the same branch propagates somewhere — so an exception cannot cover a branch that discards status everywhere, and a stale entry fails the step.

Tests

tests/delegated-exit-code-smoke.sh (stubbed, precise): step 10 grew to ten propagating paths, step 11 to eight deliberate zeros, and a new step 12 stubs hal-terminal-guide.sh through a fake BASE_DIR for both apps paths.

tests/menu-exit-contract-smoke.sh (real commands, coarse): all four contract points end to end through bin/mqlaunch, headless and on a pty with closed stdin, including the "drawn exactly once" half — exiting 0 by looping forever would satisfy a status-only check.

Both proven able to fail:

theme menu path propagates again      stops at delegated-exit-code step 11
apps discards status on every path    stops at delegated-exit-code step 7
theme apply back to exit 1            stops at menu-exit-contract step 6
theme menu propagates again           stops at menu-exit-contract step 2

Three things the work surfaced

1. The registry validator reads the literal menu) arm. Lifting the menu case into a guard above the case removed it, and the validator reported system: registry lists subcommand 'menu' but dispatch does not. The menu path went back inside the case and returns 0 from within it.

2. hal is not a menu. The headless sweep found it answering 0 and I listed it as one. It delegates to mq_hal_run, a bridge into the mq-hal repo, so on a machine without mq-hal it returns 127 — the correct answer, and CI is exactly that machine. Removed from the list, with agent, obsidian and stack absent for the same reason.

3. mq-zsh-theme-switcher.sh could only run from $HOME/macos-scripts. It read ${HOME}/macos-scripts outright where doctor.sh and scan.sh both read ${MACOS_SCRIPTS_HOME:-$HOME/macos-scripts}, so any other checkout exited 1 with Missing UI library before its first command. Found by CI. Fixed to match its siblings. terminal/themes/mq-theme-manager.sh has the same line and is untouched.

Full suite green, registry validator green, shellcheck clean, markdownlint clean.

With this the P2 section is Status: Complete.

🤖 Generated with Claude Code