# fix: avoid `topic` fallback for non-Latin titles via pragmatic ASCII
transliteration
> **Scope update (in response to review):** this PR is intentionally
broader than its original "Arabic-only" framing. The implementation
changes URL slug generation for **every non-Latin, non-CJK script** that
`slugify` previously stripped — see *Scope* below for the explicit list.
The goal is *not* linguistically correct romanization; it is "avoid
collapsing to `/topic` by producing a usable ASCII slug."
## What this PR is (and isn't)
**Goal:** when a question title contains characters outside Basic Latin
/ Latin Extended / CJK Han, generate a URL slug that is a deterministic
ASCII approximation instead of letting `slugify` strip everything and
falling back to the literal `"topic"`.
**Non-goal:** this is *not* a linguistically correct multi-language
romanizer. The output is a machine-acceptable ASCII slug, not what a
native speaker would choose. For example, `こんにちは` → `konnichiha` (not
the more natural `kon'nichiwa`), `ไทย` → `aithy` (not `thai`). Treat the
slug as an opaque, stable, indexable identifier — the
path-after-`/questions/<id>/` is for SEO and shareability, the canonical
reference is always the ID.
## The bug
Pure non-Latin titles previously got stripped by `slugify.Slugify`, hit
the empty-result fallback in `htmltext.UrlTitle`, and collapsed to the
literal slug `"topic"`. On a live multilingual site, every Arabic / Thai
/ Japanese-hiragana / Korean / Hebrew / Cyrillic question ended up at
`/questions/<id>/topic`.
## The fix
`UrlTitle()` gets a `convertNonLatin` pre-step that mirrors the existing
`convertChinese` pre-step pattern, using
`github.com/mozillazg/go-unidecode` (same author as `go-pinyin` already
in the repo, to minimise new-dep friction).
```
UrlTitle(title)
→ convertChinese(title) // pre-existing: Han-block → pinyin
→ convertNonLatin(title) // NEW: detect non-Latin letters → unidecode to ASCII
→ clearEmoji / slugify / url.QueryEscape / cutLongTitle (unchanged)
```
The non-Latin detector skips ASCII, Latin-1 Supplement, Latin
Extended-A/B, and CJK Han. Inputs that hit none of those non-Latin
letter categories short-circuit and return unchanged, so Latin-only and
Chinese-only inputs remain byte-identical (pinned by tests).
## Scope — what scripts are affected
This PR changes behavior for **any** title containing letters in scripts
that `slugify` doesn't handle. Confirmed by tests in
`pkg/htmltext/htmltext_test.go`:
| Script | Example title | Before | After |
| --- | --- | --- | --- |
| Arabic | `كيف حالك` | `topic` | `kyf-hlk` |
| Mixed Latin + Arabic | `مرحبا hello` | `hello` | `mrhb-hello` |
| Thai | `ไทย ไทย` | `topic` | `aithy-aithy` |
| Japanese hiragana | `こんにちは` | `topic` | `konnichiha` |
| Korean | `안녕하세요` | `topic` | `annyeonghaseyo` |
| Hebrew | `שלום עולם` | `topic` | `shlvm-vlm` |
| Cyrillic | `Привет мир` | `topic` | `privet-mir` |
**Unchanged:**
| Case | Behavior |
| --- | --- |
| Pure Latin (`hello world`) | unchanged → `hello-world` |
| Pure Chinese (`这是一个，标题，title`) | unchanged → `zhe-shi-yi-ge-biao-ti`
(pinyin path) |
| Japanese with Han-block kanji (`日本`) | unchanged → `ri-ben` (caught by
pre-existing pinyin path; treated as Chinese reading, not Japanese — a
pre-existing limitation, **not** introduced by this PR) |
| Emoji only (`😂😂😂`) | unchanged → `topic` |
| Empty / whitespace | unchanged → `topic` |
## Transliteration quality — explicit acknowledgement
`go-unidecode` is a generic Unicode → ASCII approximation. It is **not**
a per-language romanization library. Specifically:
- It will pick *one* approximation per codepoint regardless of language
context. `ใ` → `ai` (Thai romanization is `i` or `ai` depending on
standard), `한` → `han`, `語` → `Yu` (Chinese pinyin reading even when
used in Japanese), etc.
- The result is *good enough* to be a stable, URL-safe,
human-recognizable handle, but speakers of the source language will not
consider it "correct."
- It is deterministic, so the same title always produces the same slug —
important since `url_title` is recomputed on every request.
If maintainers prefer to scope this PR more narrowly (e.g. Arabic only,
and reject Thai/Hebrew/Cyrillic/etc.), the detector in
`containsNonLatin` can be tightened to specific Unicode blocks — but
that means the other scripts continue to collapse to `topic`, which is
the bug we're trying to fix. I'd argue the broader fix is preferable to
a piecemeal one, but happy to narrow if you want.
## Live deployment / real-world verification
This patch has been running in production on
**[ask.namasoft.com](https://ask.namasoft.com)** (an Apache Answer
instance we operate) since deployment, built directly from this branch
via `docker compose build`. The site hosts Arabic-language questions, so
the fix exercises the affected code path on every page load.
Sample question URL on the deployed instance:
> `https://ask.namasoft.com/questions/10010000000000115`
The slug in the URL is the transliterated Arabic title rather than
`topic`. No data migration was needed since `url_title` is computed on
every request from `Title` and never persisted (see *Why this is safe to
ship* below).
## Admin-configurable
The transliteration is gated by a package-level `atomic.Bool` (default
**on**, since the current behavior is objectively broken for affected
users):
- `htmltext.SetTransliterateNonLatin(enabled bool)`
- `htmltext.IsTransliterateNonLatinEnabled() bool`
This is deliberately the minimum surface needed to satisfy "the setting
must be readable from `UrlTitle()`". A follow-up PR can add an admin UI
section that calls `SetTransliterateNonLatin` on save and on startup,
without having to re-plumb every `htmltext.UrlTitle` call site through
`context.Context`.
**Default choice — please confirm:** I picked **default-on** because the
existing `topic` behavior is a bug for affected users. If you'd prefer
default-off for strict backward compat on existing installs, flip the
`init()` in `pkg/htmltext/htmltext.go` to `Store(false)` and surface the
toggle as opt-in.
## Why this is safe to ship
- `url_title` is **not** a persisted column. It's not on the `Question`
entity in `internal/entity/question_entity.go`, no migration has ever
added/dropped it, and every call site (`question_service.go`,
`revision_service.go`, `vote_service.go`,
search/report/review/rank/comment services, controllers, repos)
recomputes it from `Title` at response-build time via
`htmltext.UrlTitle(...)`.
- That means the fix is read-only: existing rows light up with correct
slugs on the next request, with no migration and no data rewrite.
- Rollback is just redeploying the prior image; nothing on disk changes.
## Test coverage
`pkg/htmltext/htmltext_test.go`:
- **`TestUrlTitleTable`** — table-driven, one case per affected script
(the full matrix above), plus:
- `empty` → `topic`
- `pure latin unchanged` → byte-identical to pre-fix
- `pure chinese unchanged` → byte-identical to pre-fix (pins existing
pinyin behavior)
- `japanese kanji goes through pinyin path unchanged` → documents the
pre-existing Han-block limitation
- `emoji only falls back to topic` → unchanged
- `long arabic truncates at cutLongTitle boundary` → exercises the
150-byte cap and UTF-8 boundary safety
- **`TestUrlTitleTransliterationToggle`** — with the toggle off,
non-Latin titles collapse to `topic` (pre-fix behavior); with it on,
they transliterate.
- Existing `TestUrlTitle` left untouched.
Test plan for reviewers:
- [ ] `go test ./pkg/htmltext/...` — all pass
- [ ] Visit the live sample URL above and confirm slug is
transliterated, not `topic`
- [ ] Verify Chinese / Latin / emoji-only / empty behavior is
byte-identical to `main` (covered by table tests)
## Out of scope (intentionally)
- No admin UI / site setting plumbing in this PR — see
*Admin-configurable* above. Happy to do the React `Non-Latin Languages
Handling` admin page + `SiteType` + service / controller / migration in
a follow-up if maintainers want it.
- No change to the `"topic"` empty-result fallback.
- No plugin interface for slug generation — mirrored the existing
`convertChinese` pre-step pattern instead.
- No per-language romanization library — this is an explicit non-goal;
see *Transliteration quality* above.
## Issues / discussion
I didn't find an existing upstream issue covering this — happy to be
pointed at one if there is.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
---------
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-authored-by: LinkinStars <linkinstar@foxmail.com>
Ahmed Qasid
a6d867e4cc