`Command.description` has always been required and has always been
rendered by `help.list-commands`. It was missing at the one moment it
would change a decision: the M-x row. This carries it there.
COHERENCE.md §5's clause "M-x rows are still bare names", per
docs/discovery-stage2-framing.md revision 3.
## The wire half is additive, and the old variant is FROZEN
postcard is not self-describing: enum variants encode by index and
fields by position. Widening `MinibufferPrompt.candidates` in place
would make every v12–v22 peer MIS-DECODE the bytes rather than ignore
them — and gating the widened form at `>= 23` would not rescue them
either, because with only one variant to gate they would receive no
minibuffer message at all. Compatibility requires the old shape to
still exist AND still be sent.
So `MinibufferPrompt` is retained unchanged for `12..=22`, and
`MinibufferPromptRows { prompt, input, cursor, rows, selected, total }`
is APPENDED as the final variant, carrying `MinibufferRow { label,
detail: Option<String> }`. A new row type, not `CompletionPopupRow`,
whose `kind` is an LSP `CompletionItemKind` code with no honest value
for a command (Q#D2-1).
Exactly one of the two reaches any peer, ever. The producer selects on
the session's negotiated version, so the CLOSE necessarily uses the
same family as the OPEN — a rows session closed by a legacy clear
leaves the dropdown on screen forever. The daemon's write loop gates
both directions again, with the legacy gate written as a RANGE
(`12..MINIBUFFER_ROWS_MIN_VERSION`) rather than a floor, so a v23 peer
cannot receive both and double-render.
`ADVERTISED_PROTOCOL_VERSION` stays 20, untouched.
## The TUI half involves no wire at all
`src/editor.rs` contains zero references to `MinibufferPrompt`:
`paint_minibuffer` reads `core.minibuffer` directly. So it reads
`Command.description` from the registry in-process, which is why this
half is independent of the bump.
Clipping is three ORDERED steps (§3.4), and the guarantee is "never a
PARTIAL name", not "the name always survives" — the prompt and typed
input consume the budget first, so the remainder can be too small even
for the bare name. If the whole name does not fit, the suffix is
omitted entirely; only once it fits is a description attempted; a
description that does not fit whole is dropped, leaving today's
`[name]`. No ellipsis stub, and no prefix of a name is ever emitted.
## Verification
`src/protocol.rs` gains this repo's FIRST literal postcard byte
fixtures: `minibuffer_prompt_v12_wire_bytes_are_frozen`, open and
cleared. A round-trip freezes nothing — it encodes and decodes with
the same types, so a field addition leaves it passing while every
shipped peer breaks. Bite-verified: reordering two fields of
`MinibufferPrompt` leaves `minibuffer_prompt_round_trips_through_postcard`
green and fails the fixture.
`line_wrap_facts_encoding_is_unchanged_by_the_v23_build` pins the
PREVIOUS final variant, per the handoff §4 rule that an appended
variant's own round-trip cannot detect a discriminant shift.
`tests/discovery_stage2_acceptance.rs` runs ONE daemon serving a v22
and a v23 session simultaneously, through the real M-x key path, and
asserts each receives its own variant AND ONLY its own — open and
close alike — by collecting every minibuffer message rather than
filtering for the expected one.
No cross-version cache test, deliberately (§3.2):
`SemanticRenderState::for_peer` bakes the negotiated version in at
attach and is dropped at detach, so a cache cannot span two versions.
A test for an impossible condition passes forever while teaching the
next reader that the hazard is real.
Five version assertions updated, each read before editing:
`src/protocol.rs` (the `PROTOCOL_VERSION` tripwire, renamed; and the
v6-floor ladder's accepted/rejected ranges),
`tests/statusline_segments_acceptance.rs`,
`tests/bottom_panel_stage2b_gpu_acceptance.rs`,
`tests/vterm_stage3_acceptance.rs`. No `ADVERTISED_PROTOCOL_VERSION`
assertion fired.
Gates: `scripts/gate --protocol --acceptance discovery_stage2_acceptance`
— all ten green, including the strengthened two-configuration sweep.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016bqGA6s9tTUFzYpbeW3tai
Levi Neuwirth
70e5781420