fix: preserve source locale when duplicating content

[edrpls]

What does this PR do?

Fixes ContentRepository.duplicate() dropping the source entry's locale. It generated the copy's unique slug scoped to the source locale, then called create() without a locale, so the fallback landed every copy in en regardless of the source row's locale.

Two observable consequences on non-English content, both hit in production on an es-canonical site (emdash 0.31.1):

• The admin content list is scoped to the active locale, so clicking Duplicate appears to do nothing — the copy is born under en and is invisible in the list the editor is looking at. Stray -copy rows accumulate (18 on the audited production DB).
• Because the slug-uniqueness check ran against the source locale while the insert landed in en, duplicating could crash with a UNIQUE(slug, locale) constraint violation when the generated slug already existed in en.

The fix passes locale: original.locale ?? undefined through to create(), which also makes the slug-uniqueness scoping consistent with the inserted row. Duplicates keep getting a fresh translation group (a duplicate is a new entry, not a translation) — that was already create()'s default behavior, and a new test locks it in so it can't regress.

Found during a measured database audit of a production deployment (the Macabro festival site).

Type of change

• Bug fix
• Feature (requires maintainer-approved Discussion)
• Refactor (no behavior change)
• Translation
• Documentation
• Performance improvement
• Tests
• Chore (dependencies, CI, tooling)

Checklist

• I have read CONTRIBUTING.md
• pnpm typecheck passes
• pnpm lint passes
• pnpm test passes (or targeted tests for my change)
• pnpm format has been run
• I have added/updated tests for my changes (if applicable)
• User-visible strings in the admin UI are wrapped for translation (if applicable). Do not include messages.po changes except in translation PRs — a workflow extracts catalogs on merge to main. — n/a: no admin UI strings changed
• I have added a changeset (if this PR changes a published package)
• New features link to an approved Discussion — n/a: bug fix

AI-generated code disclosure

• This PR includes AI-generated code — model/tool: Claude Fable 5 (Claude Code)

Screenshots / test output

Failing first (on main, before the fix):

× duplicate() preserves the source item's locale
  → expected 'en' to be 'es'
× duplicate() does not collide with the generated slug in another locale
  → UNIQUE constraint failed: ec_post.slug, ec_post.locale

After the fix:

Test Files  3 passed (3)
     Tests  141 passed (141)   (i18n.test.ts, content.test.ts, content-handlers.test.ts)

🤖 Generated with Claude Code

[changeset-bot]

🦋 Changeset detected

Latest commit: de95137

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 17 packages

Name	Type
emdash	Patch
@emdash-cms/cloudflare	Patch
@emdash-cms/sandbox-workerd	Patch
@emdash-cms/plugin-mcp-smoke	Patch
@emdash-cms/fixture-perf-site	Patch
@emdash-cms/perf-demo-site	Patch
@emdash-cms/cache-demo-site	Patch
@emdash-cms/do-demo-site	Patch
@emdash-cms/do-solo-demo-site	Patch
@emdash-cms/admin	Patch
@emdash-cms/auth	Patch
@emdash-cms/blocks	Patch
@emdash-cms/gutenberg-to-portable-text	Patch
@emdash-cms/x402	Patch
create-emdash	Patch
@emdash-cms/auth-atproto	Patch
@emdash-cms/plugin-embeds	Patch

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commit: de95137

[emdashbot]

This is a narrowly-scoped, correct bug fix. ContentRepository.duplicate() already generated a unique slug scoped to original.locale, but it called create() without a locale, so SQLite's default en landed every copy in the wrong locale (and could cause a (slug, locale) unique-constraint collision when the generated slug existed in en). Passing locale: original.locale ?? undefined makes the slug check and the insert consistent.

I read the diff, the full repository implementation and input types, the duplicate route/handler, and the existing duplicate tests. The change:

• Uses the existing CreateContentInput.locale field, so no type or API surface changes are needed.
• Correctly handles null locale values via ?? undefined (the input type doesn't accept null).
• Keeps the fresh-translation-group behavior, which create() already enforces.
• Adds three focused integration tests that reproduce the reported symptoms: missing copy in source locale, fresh translation group, and cross-locale slug collision.

No AGENTS.md conventions are violated: there are no new logged-out queries, no raw SQL interpolation, no UI string changes, the changeset is present and written for users, and the tests exercise observable behavior rather than asserting implementation details back at themselves. The code is clean.

[khoinguyenpham04]

Thanks!