feat(argv,derive): add compiled clause support

[jdx]

Summary

• add clause tables and boundary events to the zero-allocation argv parser
• support typed Vec clause fields through usage derive
• add equivalent Go parser, spec-lowering, and generated-table support
• extend the shared corpus so interpreted Rust, compiled Rust, and Go agree
• report clause addition, removal, and separator changes as breaking in usage diff

Stack

• Depends on feat(spec,parse): add repeatable clause groups #1321

Test plan

• mise run test
• mise run lint
• mise run render
• mise run gen-shadow
• cd go && go test ./...

AI-assisted — Tool: Codex; model: OpenAI/GPT-5; version: unavailable.

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Note

Medium Risk
Changes core positional parsing and completion cursor rules across Rust and Go; spec clause changes are intentionally breaking, but behavior is covered by new corpus and conformance tests.

Overview
Adds repeatable clause support: a command can declare one separator-delimited positional group (e.g. :::) whose inner arguments reset on each boundary instead of overwriting the previous instance.

The argv parser gains Command.clause, a ClauseSeparator event, and positional binding through the clause’s inner args (including after restart tokens and when automatic -- stops flags). Completions, help/usage, and spec emission now treat clause positionals like ordinary args, with usage showing a repeatable [separator …]… pattern.

Derive supports #[usage(clause, separator = "…")] on Vec<T> (T: Args) with partial/build/apply wiring; Go mirrors the same parser, help, spec lowering, and generated Parse structs. Conformance and a new corpus section expect a clauses map of per-instance arg bindings; usage diff marks clause add/remove/separator changes as breaking.

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[github-actions]

Instruction counts

benchmark	trend	instructions	Δ	wall (min)	Δ
markdown	▁█	341,669,288 → 341,722,706	+0.02%	28.58 → 28.92ms	+1.19%
startup	█▁	908,601 → 908,017	-0.06%	0.90 → 0.86ms	-4.06%

No instruction-count regression above 1%.

_{Only instruction counts gate. Wall clock is shown for context — on identical hardware it moves 4-20% run to run.}

_{Measured by tak — instruction-counted CLI benchmarks, stored in this repository's git notes.}

Shadow comparison

Parsing mise use -g node@20 against a shadow of mise's committed spec.
Reported, not gated: the shadow grows as the derive learns to express more, so
what to watch is the ratio rather than either column.

framework	stripped binary, bytes
usage	1340672
bpaf	2493280
clap	3101832

framework	instructions, cold parse	vs usage
usage	8523	—
clap	6315248	740x
bpaf	21909169	2570x

                                              min       p01       p10    median
usage-rs: argv -> struct                      429       434       439       447  ns
clap: build tree + parse -> struct         515041    516240    519114    524091  ns
bpaf: build parser + parse -> struct      1571372   1571372   1576426   1593168  ns

usage: argv -> struct                             481 ns      0.48 µs
clap: build tree + parse -> struct             529092 ns    529.09 µs
clap: parse -> struct, tree reused              23275 ns     23.27 µs
clap: build tree only                          323494 ns    323.49 µs

_{8703b562b08a vs af6ee72adaaa · measured on the runner, not pushed to the history.}

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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