fix(spec): split a clap default by the delimiter clap splits it by

[jdx]

value_delimiter = ',' means clap splits every value before anyone sees it, defaults included — so default_value = "a,b,c" is three values and never the joined string. The conversion recorded the string.

mise's --fs-events is where it shows:

#[arg(long = "fs-events", default_value = "create,remove,rename,modify,metadata",
      value_delimiter = ',', value_name = "EVENTS")]
pub filter_fs_events: Vec<FsEvent>,

and the spec that came out:

flag --fs-events var=#true default=create,remove,rename,modify,metadata {
    arg <EVENTS> { choices access create remove rename modify metadata }
}

A default its own choices node forbids. Nothing read it strictly enough to complain, which is the only reason it went unnoticed; a reader that does check — and the derive on top of this stack now does — refuses the CLI outright.

The spec has no delimiter of its own. It has a list, which says the same thing, so the fix is to write the list. Only where clap declares a delimiter: "a,b" without one is a value containing a comma, and splitting on speculation would corrupt every path list.

Verification

Built mise against this branch and regenerated its spec; --fs-events comes out as

default {
    create
    remove
    rename
    modify
    metadata
}

every word one of the declared choices. benches/mise.usage.kdl is updated to that, in the commit above it, since that is where the shadow reads it.

Mutation: ignoring the delimiter fails a_delimited_default_becomes_the_values_clap_would_split_it_into. 404 lib tests green.

AI-assisted — Tool: Claude Code; model: anthropic/claude-opus-5; version: unavailable.

---

Note

Low Risk
Narrow change to clap-to-spec metadata conversion with a targeted test; no runtime CLI parsing behavior in this PR.

Overview
Clap → spec conversion now records defaults the way clap actually applies them: when an arg has a value_delimiter, default strings are split into multiple spec default entries instead of one joined string.

A shared default_values helper drives both SpecArg and SpecFlag clap bridges, fixing cases like delimited multi-value flags whose recorded default violated their own choices (e.g. mise --fs-events). Without a delimiter, defaults stay a single string (commas preserved).

A regression test covers delimited vs non-delimited behavior.

^{Reviewed by Cursor Bugbot for commit 5cd2095. Bugbot is set up for automated code reviews on this repo. Configure here.}

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[greptile-apps]

Greptile Summary

The PR aligns generated usage-spec defaults with clap’s declared value delimiter.

• Adds a shared helper that splits clap defaults only when the argument declares a delimiter.
• Uses the normalized defaults for both positional arguments and flags.
• Adds regression coverage for delimited defaults and literal comma-containing defaults.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
lib/src/spec/arg.rs	Adds shared delimiter-aware clap default conversion and applies it to positional arguments.
lib/src/spec/flag.rs	Reuses the shared default conversion for flags.
lib/src/spec/mod.rs	Adds regression coverage for delimited and non-delimited comma-containing defaults.

_{Reviews (4): Last reviewed commit: "fix(spec): split a clap default by the d..." | Re-trigger Greptile}

[github-actions]

Instruction counts

benchmark	trend	instructions	Δ	wall (min)	Δ
markdown	▁▁▁▁▁▂▂▇█	177,370,938 → 177,568,833	+0.11%	16.94 → 16.56ms	-2.24%
startup	▁▁▇▁▁▇▁▂█	1,221,836 → 1,221,988	+0.01%	1.04 → 1.09ms	+4.57%

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.

	usage	clap	ratio
instructions, cold parse	72182	5893587	81x

usage: argv -> struct                            1277 ns      1.28 µs
clap: build tree + parse -> struct             497855 ns    497.85 µs
clap: parse -> struct, tree reused              23046 ns     23.05 µs
clap: build tree only                          306996 ns    307.00 µs

_{5cd20957094d vs f68fef4b25ee · measured on the runner, not pushed to the history.}