feat(types): a user-defined type claims its label as an alias

[Stvad]

What

A user-defined type (block-type block) doubles as a navigable page — it already carries PAGE_TYPE — but createTypeBlock only wrote content + block-type:label, never an alias. That left a parity gap with the rest of the reference system:

• Typing [[Task]] for an existing "Task" type missed the alias index and minted a separate alias-seat page, so a workspace could end up with two "Task" pages.
• The user-defined-types design (docs/user-defined-types/design.html) is explicit that the type is the [[label]] page — the block-id is the type-id, i.e. the same id [[Person]] references already resolve to.

Change

createTypeBlock now sets alias = [label] on the new type-definition block.

• Reference resolution is lookup-first, so [[label]] now resolves to the type block instead of creating a duplicate seat.
• Rename parity is self-maintaining: writeBlockTypeLabel keeps content in lockstep with the label, and the existing aliasSyncProcessor reconciles content → alias — so the alias tracks the label with no new wiring (covered by alias/test/syncProcessor.test.ts, "replaces old content entry").

Consequence (behavior change)

A type's name is now workspace-unique: the block_aliases_workspace_alias_unique trigger rejects creation — as a structured alias.collision — when a live block already claims the label. A duplicate-named type was ambiguous for [[label]] resolution anyway. The ExtractTypeDialog already surfaces the error message. (Adopting an existing page as a type — the deferred Roam-isa "promote to type" flow — remains out of scope.)

Tests

• typeExtraction.test.ts: assert the created type carries alias = [label]; new tests that [[label]] (aliasLookup) resolves to the type block and that a label colliding with an existing page alias is rejected (alias.collision). Updated the "distinct ids on repeat calls" test to use distinct labels (its intent is fresh block ids, not shared names).
• yarn run check green (compile, lint, 4199 tests).

Also refreshes the design.ts sketch to match and fixes its stale createChild import path.

🤖 Generated with Claude Code

https://claude.ai/code/session_01BjEKpBXkcqBgMTLNNjepzy

---

Generated by Claude Code

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: adc9eda35b

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[chatgpt-codex-connector]

Backfill aliases for existing type blocks

When a workspace already has user-defined types created before this change, only new createTypeBlock calls execute this write, so those existing block-type rows never claim their labels. aliasSyncProcessor skips rows with an empty alias list and writeBlockTypeLabel only changes label/content, so renaming an old type still won't seed an alias; after upgrade, [[Task]] can still miss the existing type and mint a duplicate alias-seat page unless a workspace backfill/migration seeds these aliases or handles collisions.

Useful? React with 👍 / 👎.