Web Documents: inline text/code viewer (xml, ts, js, html, …) like mobile, not download-only

[ehsan6sha]

Summary

Open text/document files inline in the web app (files.fx.land/app/) like the mobile app, instead of only downloading. Today the web bucket screen only treats .txt/.md/.json/.csv/.log (+ text/*, application/json MIME) as inline-viewable and renders them as a bare SelectableText in a small dialog; everything else — including .xml, .ts, .js, .html, .yaml, .py, etc. — falls through to download. So the document types users care about feel download-only.

Native reference

lib/features/viewer/screens/text_viewer_screen.dart + lib/core/models/local_file.dart (isTextViewable):

• Inline-viewable extensions (40+): txt, md, rtf, csv, log, ini, conf, cfg, json, xml, yaml, yml, sql, dart, js, ts, jsx, tsx, vue, py, java, kt, swift, c, cpp, h, cs, go, rs, rb, php, html, css, sh, gradle, properties, env, gitignore, dockerignore, makefile, cmake.
• Code extensions get a dark editor theme (#1E1E1E bg, white text, monospace): dart, js, ts, py, java, kt, swift, go, rs, c, cpp, h, css, html, xml, json, yaml, yml, sh, bash.
• Full-screen viewer: AppBar with filename + "N lines • size"; actions = search toggle, go-to-line (disabled when wrap on), copy-all, settings menu (larger/smaller text 10-24pt, wrap toggle, line-numbers toggle).
• Line-number gutter (toggle); wrap mode = variable-height ListView with soft-wrap; no-wrap mode = horizontal scroll with fixed item height.
• Search: case-insensitive, highlights matched substrings (yellow), match counter i/N, prev/next, scroll-to-match.
• JSON pretty-printed (indent 2) when < 5 MB.

Web plan

• New pure, VM-testable logic file (no package:web/dart:ui): extension parsing (mirrors native incl. dotfiles/Makefile), isTextViewable, isCode, JSON pretty-print, line-match search — so the classification + helpers are unit-tested.
• New full-screen web text viewer widget mirroring the native UX (line numbers, code dark theme, font sizing, wrap toggle, search w/ highlight + next/prev, go-to-line, copy-all, download, JSON pretty-print). Rendered as a full-screen dialog (consistent with the app's existing dialog-based previews; keeps download + Recent recording in the bucket screen so Web Home: add Recent section (recently-opened cloud files) like the mobile app #17 keeps working).
• Bucket screen: expand the inline-text classification to the native list (+ text/*, application/json, application/xml MIME) so xml/ts/js/html/etc. open inline; route text to the new viewer; binary/over-cap → download fallback.
• Decode bytes as UTF-8 lenient (malformed → replacement char). Generous size cap for inline rendering; above it, download instead.

Acceptance

• Opening a .xml/.ts/.js/.html/.yaml/.py/.md/.csv/... document in the web app shows it inline in a mobile-style viewer (not a download).
• Code files render in the dark editor theme; line numbers, font sizing, wrap, search (with highlight + nav), copy-all, download all work; JSON pretty-printed.
• No regression to image/media preview, download, or the Recent strip (Web Home: add Recent section (recently-opened cloud files) like the mobile app #17). analyze + unit tests + web build green; live.

Part of the mobile->web parity work.