pi-di18n

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pi-di18n is the localization extension for pi. It continues the full TUI i18n and core-hacks line from pi-i18n, integrates summary localization from pi-compaction-i18n, and adds LLM-facing tool-description localization through /lang think.

What It Localizes

pi-di18n has three localization lines:

Line	Audience	Scope
A-line: TUI localization	Human user	Buttons, selectors, status/warning/error messages, slash-command descriptions, session selector text
B-line: thinking localization	LLM	Tool and parameter description strings sent in provider payloads
C-line: summary localization	Human user	/compact and /tree summaries

Features

• Full TUI localization — keeps core-hacks to runtime-patch pi internal render paths, covering UI labels, selectors, status messages, and built-in slash-command descriptions.
• Slash-command description fix — ships pi.slash.<name>.description bundle keys for all pi 0.79 built-in slash commands, including zh-CN.
• Session selector translation — covers visible session-selector strings such as Resume Session, Threaded, Recent, Fuzzy, and delete prompts.
• Non-invasive status bar — does not replace pi's native footer/status bar, so model, cwd, token, git, and worktree information remain visible.
• Runtime UI description localization — asynchronously localizes extension, prompt-template, and skill command descriptions for autocomplete UI, then caches them locally without blocking rendering.
• LLM thinking-language localization — /lang think on replaces tool and parameter descriptions in provider request payloads so the model reads them in the active /lang locale.
• Provider payload coverage — supports OpenAI-style, Anthropic, and Google/Gemini tool schemas:
  • OpenAI-style: tools[].function.description and function.parameters.properties.*.description
  • Anthropic: tools[].description and input_schema.properties.*.description
  • Google/Gemini: tools[].functionDeclarations[].description and parametersJsonSchema.properties.*.description
• Prefilled baseline translations — includes offline baseline translations for 12 languages: zh-CN, zh-TW, ja, ko, ru, vi, es, pt-BR, de, fr, id, hi.
• Runtime fallback and cache — descriptions missing from the baseline are translated with the current session model and cached under ~/.pi/agent/state/pi-di18n/think.json with English-source invalidation.
• Summary localization — intercepts session_before_compact and session_before_tree so compaction and branch summaries follow the active /lang locale.
• Extension i18n API compatibility — preserves pi-i18n/requestApi and pi-core/i18n/requestApi events for other extensions.

Installation

Once published:

pi install npm:pi-di18n

For local development:

pi install /absolute/path/to/pi-di18n

Then restart pi, or run /reload.

To test this checkout without loading installed extensions:

pi -ne -e /absolute/path/to/pi-di18n/index.ts --offline

Usage

Basic language setup:

/lang setup beginner
/lang zh-CN
/lang debug
/lang probe

Enable LLM-facing thinking localization:

/lang think on
/lang think doctor

Disable it:

/lang think off

Clear cached runtime translations:

/lang think clear      # clear current locale
/lang think clear-all  # clear all locales

Summary localization needs no extra command. It runs automatically when /compact or /tree branch summaries are triggered, and follows the current /lang locale.

/lang think Behavior

/lang think does not set a separate language. It follows the current /lang locale.

/lang zh-CN
/lang think on

The feature is off by default. When enabled, it uses a three-layer lookup:

1. prefilled baseline translations shipped with the package;
2. local cache with English-source invalidation;
3. runtime LLM fallback using the current session model.

Safety boundary: only prose description strings are translated. Tool names, parameter names, type, enum, defaults, values, and schema structure are never translated.

Diagnostics

/lang debug
/lang probe
/lang think doctor

/lang think doctor reports:

• current locale and enabled state;
• session tool/parameter counts;
• baseline coverage;
• cache counts;
• stale entries whose English source changed;
• pending descriptions that still need runtime translation.

Development

npm install
npm test
npm pack --dry-run

Current verification commands:

npm test
npm pack --dry-run

See doc/40-版本实施方案/verification-2026-06-17.md for a dated verification snapshot and detailed records.

Directory Layout

Path	Description
index.ts	Extension entry point; registers /lang, core-hacks, thinking localization, and summary-localization hooks
src/core-hacks.ts	Runtime patches for TUI localization
src/pi-ui.ts	Localization for tool rendering, buttons, and other UI surfaces
src/compaction/	Localization for /compact and /tree summaries
src/think/	B-line LLM thinking-language localization
src/ui-localize/	A-line runtime UI description localization for extension/prompt/skill autocomplete descriptions
src/think-locales/	Prefilled baseline translations: en source + 12 target languages
scripts/	Maintenance scripts for exporting and refreshing generated baseline sources
scripts/export-think-baseline.mjs	Export pi built-in tool descriptions as baseline source; re-run on pi upgrade
locales/	i18n bundles
src/core-hacks-locales/	Exact/substring translation packs for core-hacks
tests/	vitest regression tests
doc/	Architecture notes, roadmap, ADRs, verification records, glossary

Compatibility

The baseline target is @earendil-works/pi-coding-agent 0.79.x.

pi currently has no native full TUI i18n API. TUI localization therefore depends on best-effort core-hacks that patch pi internal render paths. After every pi upgrade, run:

/lang debug
/lang probe

and also:

npm test
npm pack --dry-run

Changelog

See CHANGELOG.md for released versions and user-visible changes.

License

MIT