[#2] Add slugify() string helper #3

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ernest wants to merge 1 commit from agent/issue-2 into main

ernest commented

2026-06-24 01:13:42 +02:00

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Summary

Adds slugify(input: string): string in src/slugify.ts — a self-contained
helper that converts free-form text to a URL-safe slug:

lowercases the input
deletes non-ASCII and non-alphanumeric characters (not transliterated, per spec)
collapses runs of spaces and dashes into a single dash
trims leading/trailing dashes

Seven tests in src/slugify_test.ts cover all five acceptance criteria from
the spec plus two regression cases discovered during review (see below).
deno task ci is green.

Step ordering — why delete first, then collapse

The intuitive order (spaces → dashes, then strip non-alnum) introduced a
correctness bug found during self-review: a non-ASCII character flanked by
dashes (e.g. "a-é-b") acts as a barrier in the collapse pass, so the two
surrounding dashes are never merged. When the character is deleted in the next
pass, two adjacent dashes remain with nothing left to collapse them.

The fix reorders to: delete non-slug chars first (keeping spaces), then
collapse all separator runs. After deletion, any consecutive dashes are visible
to the collapse pass and are merged correctly. Two regression tests pin this
behaviour: "a-é-b" → "a-b" and "-é-a" → "a".

Residual findings / deliberate omissions

Unicode dashes (—, –, etc.) are deleted rather than converted to
dashes. The spec explicitly lists only ASCII spaces as separator inputs and
says to delete non-[a-z0-9-] characters. Treating Unicode punctuation as
word separators is out of scope.
Transliteration (é → e) is explicitly out of scope per the spec
("Comportement figé : on supprime les non-ASCII").

Closes #2

## Summary Adds `slugify(input: string): string` in `src/slugify.ts` — a self-contained helper that converts free-form text to a URL-safe slug: - lowercases the input - deletes non-ASCII and non-alphanumeric characters (not transliterated, per spec) - collapses runs of spaces and dashes into a single dash - trims leading/trailing dashes Seven tests in `src/slugify_test.ts` cover all five acceptance criteria from the spec plus two regression cases discovered during review (see below). `deno task ci` is green. ## Step ordering — why delete first, then collapse The intuitive order (spaces → dashes, then strip non-alnum) introduced a correctness bug found during self-review: a non-ASCII character flanked by dashes (e.g. `"a-é-b"`) acts as a barrier in the collapse pass, so the two surrounding dashes are never merged. When the character is deleted in the next pass, two adjacent dashes remain with nothing left to collapse them. The fix reorders to: delete non-slug chars first (keeping spaces), then collapse all separator runs. After deletion, any consecutive dashes are visible to the collapse pass and are merged correctly. Two regression tests pin this behaviour: `"a-é-b"` → `"a-b"` and `"-é-a"` → `"a"`. ## Residual findings / deliberate omissions - **Unicode dashes** (`—`, `–`, etc.) are deleted rather than converted to dashes. The spec explicitly lists only ASCII spaces as separator inputs and says to delete non-`[a-z0-9-]` characters. Treating Unicode punctuation as word separators is out of scope. - **Transliteration** (`é → e`) is explicitly out of scope per the spec ("Comportement figé : on supprime les non-ASCII"). Closes #2

jleicher was assigned by ernest

2026-06-24 01:13:42 +02:00

ernest added 1 commit

2026-06-24 01:13:42 +02:00

feat: add slugify() string helper c1ab8cad44

Transforms free-form text into a URL-safe slug:
- lowercases input
- deletes non-ASCII and non-alphanumeric characters (not transliterated)
- collapses runs of spaces and dashes into a single dash
- trims leading/trailing dashes

Step ordering (delete junk first, then collapse separators) is
intentional: it prevents non-ASCII chars flanked by dashes from
leaving consecutive interior dashes after deletion (e.g. "a-é-b"
would otherwise become "a--b").

Closes #2
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

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