kfirsch/dsh-hebrew-rtl

English | עברית

Correct Hebrew RTL rendering for the DeepSeek Harness web GUI: per-block direction by dominant script, bidi-safe input fields, and RTL-aware Cmd+←/→ line navigation.

The problem

The GUI renders every block left-to-right. For Hebrew that produces three distinct failures:

1. Whole paragraphs read backwards. A Hebrew sentence is laid out as an LTR paragraph, so its lines start on the wrong side and punctuation lands at the wrong end.
2. Typing into a field runs the wrong way. The ask_user_question custom-answer field inherits the page direction, so Hebrew typed into it flows left-to-right.
3. Cmd+←/→ feel inverted. These shortcuts are logical in every browser: ← goes to the line's logical start, which on an RTL line sits at the visual right edge. Pressing ← jumps the caret to the far right.

The obvious CSS answer — unicode-bidi: plaintext — fixes only the easy half. It picks a block's direction from its first strong directional character, so a Hebrew sentence that opens with a Latin product name, a list number, or an emoji is still rendered LTR and still reads garbled.

What this plugin does

Per-block direction by dominant script

For each block element (p, ul/ol, h1–h6, blockquote, table) it drops code-like tokens from the block's text, then counts Hebrew-majority words against Latin-majority words in what remains:

Content	Result
No Hebrew prose	No override — unicode-bidi: plaintext stays in charge
Hebrew words > Latin words	direction: rtl + text-align: right
Latin words > Hebrew words	direction: ltr + text-align: left
Equal (both present)	direction: rtl — a block with as much Hebrew as Latin is Hebrew text quoting English

Forced blocks get unicode-bidi: isolate, so the Unicode Bidi algorithm still lays out the minority-script runs correctly inside the chosen paragraph direction:

היום בדקנו את הפלאגין החדש עם DSH והכול עבד מצוין.
→ RTL, and "DSH" stays in place, unreversed

This is a test sentence with שלום in the middle.
→ LTR, and "שלום" stays in place, mid-sentence

Dominance is the rule because both simpler alternatives fail in an obvious way. First-strong alone mis-renders any Hebrew paragraph that does not begin in Hebrew. "Any Hebrew character forces RTL" over-corrects in the other direction: an English sentence carrying one Hebrew word flips to RTL and its English runs come out reversed.

Why words, and why code tokens are excluded. Counting raw letters breaks on technical Hebrew prose. A single identifier can outweigh a whole paragraph — git+https://git@github.com:kfirsch/...#<sha> contributes 44 Latin letters by itself, and a commit sha another 40 — so a Hebrew sentence that merely cites a URL was rendered LTR. Identifiers, URLs, paths, shas and 15/15-style ratios are therefore stripped before counting; they are still laid out normally, they just no longer vote on the paragraph's direction. Counting whole words rather than letters follows from the same reasoning: a three-letter Hebrew word says as much about the sentence's language as credential does. The stripping is deliberately conservative — an ordinary Latin word standing alone is never treated as code, so genuine English prose still counts in full.

The heuristic is not infallible on a block that is genuinely half-and-half after stripping (a short line of mostly commit hashes with two Hebrew words, say). Those fall back to first-strong rather than guessing.

Composite elements are judged whole, never by their parts. This one rule was learned three times over:

• Tables. Judging each td separately gave a six-row status table three different verdicts — Hebrew label cells went RTL while the HEAD and Commits cells beside them stayed LTR — so the label column changed edges from row to row. Column order is a property of the table rather than the cell, so per-cell directions also fight the column order itself.
• Lists. The same failure one level down. In a Hebrew numbered list, a short all-Latin item such as push has no Hebrew to weigh, so it got no verdict at all, fell back to the page's LTR, and jumped to the opposite margin from its RTL siblings — breaking the numbering column.
• Formulas. KaTeX renders a formula as hundreds of nested <span>s whose horizontal positions it computes itself. Letting each one pick its own direction tore formulas apart: (idle + rightsizing) and $870/month came out reordered into nonsense. .katex and its whole subtree are excluded — KaTeX handles bidi itself.

So the direction is decided once per composite, from its whole text, and every part inherits it. unicode-bidi: isolate still lays out each part's own content correctly within that direction.

Blocks are re-evaluated through a MutationObserver as text streams in, coalesced with requestAnimationFrame so streaming does not trigger a scan per character.

Bidi-safe input fields

The composer and the ask_user_question custom-answer field are each a two-layer stack: a visible or measuring mirror layer plus a real <textarea> sharing one grid cell. Both layers must carry identical bidi metrics, or their computed heights and wrapping diverge and the field mis-sizes or the caret drifts away from the glyphs.

Both layers therefore receive unicode-bidi: plaintext together — never the textarea alone — so each line's direction follows what is actually typed into it.

RTL-aware line navigation

A capture-phase keydown listener intercepts Cmd+←/→ only when the caret's current line is RTL, and swaps them so each arrow points where the caret visually goes. Lines that are not RTL are left completely untouched. Shift-extension and selection direction are preserved.

Install

dsh plugin --profile web add github:kfirsch/dsh-hebrew-rtl

Then restart dsh web and hard-refresh the browser tab.

To pin an exact commit (recommended — a later push then cannot silently change what runs):

dsh plugin --profile web add github:kfirsch/dsh-hebrew-rtl#<commit-sha>

The package ships plain hand-written JavaScript in lib/ with no build step, so installing from GitHub needs no allowBuilds approval.

Uninstall

dsh plugin --profile web remove dsh-hebrew-rtl

Scope: Hebrew only, deliberately

The direction rule generalises cleanly to every RTL script — Arabic and its languages, Syriac, Thaana, N'Ko, Adlam — and that version was written and passed a 16-case script matrix. It was then reverted on purpose: neither the author nor a reviewer can proof-read those scripts, and shipping text-direction handling that nobody involved can verify is worse than not shipping it. The package name says what it actually supports.

A pull request adding another script is welcome from someone who reads it and can confirm the rendering by eye.

Compatibility

• Surface: the web profile (dsh web). No host service, no configuration, no network access.
• What it never touches: contenteditable regions and code blocks — code stays LTR regardless of its content.
• Tested against dsh 0.1.1-rc.2.

License

MIT © Kfir Schneider

For reviewers: why there is no build step

lib/ is not build output — it is the hand-written source, in the exact wire format the DSH client module system loads. There is deliberately no src/, no scripts.build and no scripts.prepack, so a clean checkout is already the artifact and a GitHub install needs no allowBuilds approval.

plugin_check flags all three of those as warnings on the assumption that a plugin is compiled; they are inapplicable here rather than unaddressed. The package passes with no errors.

Run the checks yourself:

npm test          # smoke-tests the direction rule and the caret swap