Changes Overview

Splits aimx --help into two audience-grouped sections — Operations (as current user) for per-user verbs and Server administration for operator/root verbs — by replacing clap's auto-rendered subcommand list with a hand-rolled SUBCOMMAND_HELP constant injected via {after-help}. Also retitles the tagline, drops long_about so -h and --help render identically, hides the internal ingest subcommand from top-level help, adds an explicit -V, --version flag to the parser purely so it shows in the Options block, and tightens every subcommand's one-line description.

Scope Alignment

Implementation matches the PR description exactly. Every claim verified locally:

• aimx --help and aimx -h render the new grouped layout, -V, --version appears in Options.
• New tagline renders.
• aimx --version and aimx -V still print the custom version_string() banner via handle_version_flag (intercepted in main.rs before Cli::parse() runs).
• aimx ingest --help still works (subcommand wired, just hidden from the top-level list).
• aimx mailboxes --help and other subcommand help pages are unchanged.
• aimx serve --version is correctly rejected by clap (the new version: bool field is parent-only, not global).
• cargo build, cargo test --test integration help_shows_subcommands, cargo clippy -- -D warnings, cargo fmt -- --check all clean.

No scope creep: the diff touches exactly two files (src/cli.rs, tests/integration.rs) and is limited to help-surface concerns.

Potential Bugs

None found in the changed code.

One pre-existing edge case worth noting (not introduced by this PR, since handle_version_flag is unchanged): aimx --data-dir /tmp --version does not print the banner. handle_version_flag stops scanning at /tmp because it can't tell /tmp is the value for --data-dir. Before this PR clap rejected this with "unexpected argument --version"; after this PR the new parent-level version field is consumed but no subcommand follows, so clap errors with "command required" instead. Both are error states, both pre-date this PR, and the message change is a minor UX shift in an already-unfriendly path. Mentioning here only because the PR brings the --version flag into the parser surface. Non-blocker.

Test Coverage

The integration test help_shows_subcommands was updated correctly:

• Adds positive assertions for the two new headings.
• Adds a negative assertion that ingest no longer appears in --help.
• Keeps assertions for each visible subcommand name.

Two minor gaps, both non-blocking:

• The test does not verify the order of sections (Operations before Server administration) or that subcommands appear under their intended heading. A maintainer who accidentally swapped the two halves of SUBCOMMAND_HELP would still pass the test. A simple find("Operations") < find("Server administration") < find("send") ordering check would close this.
• No assertion that -V, --version appears in the Options block, even though the PR explicitly adds a Cli::version field to make that line render.

Code Quality

• SUBCOMMAND_HELP is a hand-rolled string that must stay in sync with the Command enum. The PR comment in cli.rs:6-10 acknowledges this and asks maintainers to keep it in sync. For a 14-command surface that changes rarely this is acceptable; an automated drift guard (a unit test that walks Command::clap() and asserts each non-hidden variant is mentioned in SUBCOMMAND_HELP) would make the constant self-maintaining, but it's a nice-to-have, not required.
• Cli::version is #[allow(dead_code)] with a clear comment explaining why. Reasonable trade-off given that clap forces a struct field if you want the flag rendered.
• help_template correctly omits {subcommands} since {after-help} now carries that role; rendered output has no double-blank-lines or trailing whitespace.

Security Issues

None — this PR does not touch any code path that handles input, auth, networking, or filesystem access.

Summary and Recommended Actions

Overall verdict: Ready to merge.

• Blockers: none
• Non-blockers: none
• Nice-to-haves:
  • Add an ordering assertion to help_shows_subcommands so an accidental swap of the two headings is caught.
  • Add an assertion that -V, --version appears in the --help Options block.
  • Consider a unit test that compares Command variants against SUBCOMMAND_HELP to detect drift when new subcommands are added.

Recommended merge commit message

Group `aimx --help` subcommands by audience

Splits the flat 14-command list in `aimx --help` into "Operations (as
current user)" (send, mailboxes, hooks, agents, mcp) and "Server
administration" (setup, serve, doctor, logs, dkim-keygen, portcheck,
uninstall, upgrade) so newcomers can orient themselves at a glance.

Implementation:
- Clap 4 doesn't allow `help_heading` on subcommand variants, so the
  parent's `help_template` omits `{subcommands}` and slots a hand-rolled
  grouped list in via `{after-help}`. The list lives in a
  `SUBCOMMAND_HELP` constant with a maintainer comment.
- New tagline ("The internet's oldest protocol, rebuilt for AI agents.")
  replaces the old `about`/`long_about` pair; the multi-paragraph
  description it carried lives in the README.
- Hides `ingest` from top-level `--help` (still wired and invoked by
  `aimx serve` over stdin).
- Declares `Cli::version` purely so `-V, --version` renders in the
  Options block; `handle_version_flag` in `main.rs` still intercepts
  the flag before `Cli::parse()` runs.
- Tightens every subcommand's one-line description.

Integration test updated to assert the new headings and that `ingest`
is hidden.