Configurable language for auto-generated session titles

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• [x] This is a single feature request (not multiple features)

Problem Statement

Currently Claude Code auto-generates session titles (shown in the sessions list) based on conversation content. For users whose primary language is not English, titles often end up in English or mixed languages, making the sessions list harder to scan.
Request: add a config option to force the auto-title generator to use a specific language.
Suggested options (any would work):

1. settings.json key: "sessionTitleLanguage": "ru" (or "uk", "es", etc.)
2. Environment variable: CLAUDE_CODE_TITLE_LANGUAGE=ru
3. Instruction in ~/.claude/CLAUDE.md that the title generator also reads (currently it seems to be ignored by the title generator)

Use case: I'm a Russian-speaking developer. My conversations, project docs, commit messages and PROJECT_STATUS.md are in Russian/Ukrainian. But session titles come out in English instead of Russian, which breaks consistency in the sessions list.
Workaround today: manually rename each session. Works but tedious with many sessions per day.
Thanks!

Proposed Solution

Currently Claude Code auto-generates session titles (shown in the sessions list) based on conversation content. For users whose primary language is not English, titles often end up in English or mixed languages, making the sessions list harder to scan.
Request: add a config option to force the auto-title generator to use a specific language.
Suggested options (any would work):

1. settings.json key: "sessionTitleLanguage": "ru" (or "uk", "es", etc.)
2. Environment variable: CLAUDE_CODE_TITLE_LANGUAGE=ru
3. Instruction in ~/.claude/CLAUDE.md that the title generator also reads (currently it seems to be ignored by the title generator)

Use case: I'm a Russian-speaking developer. My conversations, project docs, commit messages and PROJECT_STATUS.md are in Russian/Ukrainian. But session titles come out in English instead of Russian, which breaks consistency in the sessions list.
Workaround today: manually rename each session. Works but tedious with many sessions per day.
Thanks!

Alternative Solutions

_No response_

Priority

Low - Nice to have

Feature Category

CLI commands and flags

Use Case Example

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Additional Context

_No response_