Browser extension: Save snippets from any webpage

[byteofhoney]

Goal:

Let users save selected code from any webpage directly into StashSnip via a right click context menu.

User story:

As a user, I want to right click selected code on any page so that I can save it without switching apps.

Depends on:

#25 this needs an API endpoint to POST snippets to before work can start.

Tasks:

• Build a minimal browser extension using Manifest V3
• Add a right click context menu entry that only appears when text is selected (e.g. "Save selection to StashSnip")
• On click, grab the current text selection (window.getSelection() in the content script)
• Show a small popup/prompt for title, language and tags before saving; don't save automatically with no metadata
• POST the snippet to the StashSnip API endpoint
• Handle the case where the API request fails (show an error in the popup, don't fail silently)
• Handle authentication/API key if the API requires one (confirm approach with maintainer before starting, since the API issue may not have this decided yet)
• Target both Firefox and Chrome/Edge from the start using the webextension-polyfill library for cross browser API compatibility, rather than building Chrome-only and porting later
• If cross browser from day one isn't feasible, build Firefox first (maintainer's primary browser) with Chrome/Edge as an explicit follow up issue

Acceptance Criteria:

• Right click menu option only appears when text is actually selected, not on every right click
• Selecting code on any webpage and completing the popup form successfully creates a new snippet
• A failed save (e.g. API down, network error) shows a clear error message in the extension popup, not a silent failure
• Saved snippet appears correctly in the main app afterward, with the correct title, language, tags and code intact
• Works on Firefox and Chrome/Edge
• Extension requires no more permissions than necessary (avoid requesting broad host permissions if activeTab is sufficient)