Bash completion duplicates colon-prefixed task names on second Tab

[dpan]

On bash, completing a namespaced task works on the first Tab, then a second Tab after typing more of the name inserts the full task name after the already-completed prefix.

This used to work. It broke after the self-contained / usage-rs completion rewrite.

Reproduction

[tasks."update:deps"]
run = "echo deps"

[tasks."update:deps:no-cooldown"]
run = "echo no-cooldown"

1. mise upd<TAB> → mise update:deps (remaining options listed)
2. Continue to mise update:deps:no<TAB>

Actual: mise update:deps:update:deps:no-cooldown
Expected: mise update:deps:no-cooldown

Cause

Bash COMP_WORDBREAKS includes :, so the current word after step 2 is only no. The completer still returns the full candidate update:deps:no-cooldown, and bash replaces only no.

The old path used __ltrim_colon_completions. The new generator does not appear to.

Environment

• version: 2026.9.1 linux-x64 (2026-09-02)
• activated: yes
• shims_on_path: yes
• self_update_available: no
• mise doctor: "No problems found"

[jdx]

Confirmed and reproduced. The completion backend returns the correct full candidate, but Bash splits the current word at : through COMP_WORDBREAKS; the new self-contained usage-rs wrapper was no longer trimming the prefix that Readline preserves. This affects colon-containing Bash candidates generally, not only mise tasks.

I opened jdx/usage#1405 with the upstream fix and regression coverage using the reported COMP_LINE/COMP_WORDS shape. The focused real-Bash tests and Clippy pass; CI is running. Once that lands and is released, mise can update usage-rs and regenerate its completions.

Thanks for the precise reproduction and diagnosis.

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