[Feature] Customize speaker names in exported transcripts

[Nagi-ovo]

🥰 需求描述 | Feature Description

Human-readable conversation exports currently use fixed User and Assistant speaker labels.

Some users give their AI persona a specific name and want that name to appear in exported transcripts. A custom user label is also useful when exported conversations are shared inside a team, where the human contributor should be identifiable.

This request concerns export presentation only. It should not rename anything in Gemini's UI or change the underlying user / assistant roles in machine-readable JSON.

🧐 解决方案 | Proposed Solution

Add a compact Speaker names section to the existing export dialog, alongside the current font-size and image-width preferences.

Speaker names

User label      [ User      ]
AI label        [ Assistant ]

Recommended behavior:

• Default to the existing localized User and Assistant labels.
• Let users override either field for the current export, for example Erik and a named AI persona.
• Remember the chosen values as export preferences for future exports.
• Treat an empty or whitespace-only value as the localized default.
• Apply the labels consistently to Markdown, PDF, and image conversation exports.
• Keep JSON role values unchanged.
• Keep the fields hidden or disabled for export types where speaker labels do not apply, such as standalone Deep Research documents.
• Escape user-provided values appropriately in Markdown and HTML output.

The export dialog is the preferred location because this is export-specific presentation metadata and the dialog already contains related controls such as font size and image width.

🔄 替代方案 | Alternatives Considered

• Popup settings: Rejected because the preference is only meaningful while exporting and would be difficult to discover later.
• Rename the roles globally in Gemini: Out of scope and could interfere with DOM role detection.
• Ask for names on every export without remembering them: More repetitive for users who consistently use the same names.
• Post-process exported files manually: Possible today, but inconvenient and inconsistent across Markdown, PDF, and image exports.

📝 补充信息 | Additional Information

Suggested placement in the existing export dialog:

┌─────────────────────────────────────────┐
│ Export Conversation                     │
│                                         │
│ ○ Markdown   ○ PDF   ○ Image   ○ JSON   │
│                                         │
│ Speaker names                           │
│ ┌─────────────────┐ ┌─────────────────┐ │
│ │ User            │ │ Assistant       │ │
│ └─────────────────┘ └─────────────────┘ │
│                                         │
│ [format-specific font size / width]     │
│                                         │
│                       Cancel   Export   │
└─────────────────────────────────────────┘

Acceptance criteria:

• Existing exports remain unchanged when defaults are used.
• Custom names appear in every human-readable conversation export path.
• JSON continues to use stable role identifiers.
• Values persist across export-dialog sessions and can be reset by clearing the fields.
• Tests cover defaults, custom values, blank fallback, escaping, persistence, and all affected export formats.

[solisseu]

/claim

[github-actions]

🎉 @solisseu has claimed this issue! / 已认领此 Issue！

Please read the Contributing Guide, reference this issue in your PR, and comment /unclaim if you can no longer continue.