René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"deepnote cat shows separator blocks as (empty) instead of ---","articleBody":"## Problem\n\n`deepnote cat` is supposed to show separator blocks as a horizontal line (`---`), as added in #242. Instead, the text output prints `(empty)`:\n\n```\n────────────────────────────────────────────────────────────\nseparator (b)\n  (empty)\n\n────────────────────────────────────────────────────────────\n```\n\n`deepnote cat \u003cfile> -o json` returns `\"content\": \"\"` for the same block.\n\n## Cause\n\nThe separator branch in `getBlockContent` never runs, because the `content` check before it always matches:\n\nhttps://github.com/deepnote/deepnote/blob/a698ad0291be8e75d841ab9404f0f5e594f0a64a/packages/cli/src/commands/cat.ts#L252-L264\n\n`cat` reads blocks through `deserializeDeepnoteFile`. Its `emptyContent()` preprocess always sets a separator's `content` to `''`, even when the file has no `content` key:\n\nhttps://github.com/deepnote/deepnote/blob/a698ad0291be8e75d841ab9404f0f5e594f0a64a/packages/blocks/src/deepnote-file/deepnote-file-schema.ts#L10\n\nSo `getBlockContent` returns `''`, and the text renderer prints `(empty)`:\n\nhttps://github.com/deepnote/deepnote/blob/a698ad0291be8e75d841ab9404f0f5e594f0a64a/packages/cli/src/commands/cat.ts#L206-L222\n\nThis has been the case since `cat` was added. TypeScript didn't flag the dead branch because the inferred type of `content` was `'' | undefined`. #597, the zod 4 migration, makes the type exactly `''`, so the comparison becomes TS2367. That PR removes the unreachable branch and doesn't change any behavior.\n\n## Proposed fix\n\n- In the text output path of `cat`, show `---` for separator blocks instead of the result of `getBlockContent`. For example, `block.type === 'separator' ? '---' : getBlockContent(block)`. `highlightContent` only colors `code` and `sql`, so `---` prints as is.\n- Leave `-o json` unchanged (`\"content\": \"\"`). JSON output carries block data, not display strings, so the check shouldn't move to the top of `getBlockContent`.\n- Add `packages/cli/src/commands/cat.test.ts` cases for a separator block in text output and in JSON output. No test covers separators today.\n\n## Acceptance criteria\n\n- `deepnote cat \u003cfile>` prints `---` for a separator block.\n- `deepnote cat \u003cfile> -o json` still returns `\"content\": \"\"` for that block.\n- Tests cover both outputs.\n","author":{"url":"https://github.com/tkislan","@type":"Person","name":"tkislan"},"datePublished":"2026-10-28T19:15:04Z","url":"https://github.com/deepnote/deepnote/issues/599"}