docs(observability): remove v4 data model comparison section

[Lotte-Verheyden]

Summary

• Removes the "Underlying data model" section from content/docs/observability/data-model.mdx, which compared the classic vs. observation-centric (v4) data model as first-class docs content.
• Same rationale as docs(metrics): move v4 dashboard changes reference to FAQ #2915 (dashboards): new users don't need to read about what changed across versions in the main docs — that belongs in the changelog and FAQ.

Disclaimer: Experimental PR review

Greptile Summary

This PR removes the "Underlying data model" section from content/docs/observability/data-model.mdx to keep version-comparison content out of the main docs (moving it to the changelog and FAQ instead), matching the rationale from #2915.

• The deleted section explained the observation-centric (v4) data model, contrasted it with the classic model in a comparison table, and included the related diagram — all of which still exist in the changelog post.
• A sibling FAQ file (content/faq/all/explore-observations-in-v4.mdx) contains a hard link to the now-removed #underlying-data-model anchor, which will silently break for readers following that link.

Confidence Score: 4/5

Safe to merge after fixing one broken anchor link in the FAQ file.

The deletion itself is clean, but it orphans a hard anchor link in content/faq/all/explore-observations-in-v4.mdx that points directly to the removed #underlying-data-model section. Readers following that FAQ's 'conceptual background' link will silently land at the top of the data model page with no indication that the content moved — a one-line fix resolves it.

content/faq/all/explore-observations-in-v4.mdx — line 18 references the removed anchor and needs to be updated.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["data-model.mdx (main docs)"] -- "previously contained" --> B["## Underlying data model\n(classic vs v4 comparison)"]
    B -- "removed by this PR" --> C["Section deleted"]
    D["faq/explore-observations-in-v4.mdx\nline 18"] -- "links to" --> E["/docs/observability/data-model\n#underlying-data-model"]
    E -- "anchor no longer exists" --> F["⚠️ Broken anchor link"]
    G["changelog/2026-03-10-simplify-for-scale"] -- "still contains" --> H["v4 data model comparison\ncontent"]

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Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 1
content/faq/all/explore-observations-in-v4.mdx:18
This PR removes the `#underlying-data-model` anchor from `data-model.mdx`, so the link on line 18 will point to a non-existent fragment. Visitors following this link will land at the top of the page with no indication that the section is gone, which is confusing given the sentence frames it as conceptual background for the v4 model. The link should either be updated to point to a surviving section or replaced with the changelog post that still contains the comparison.

```suggestion
For conceptual background, see the [data model docs](/docs/observability/data-model). For broader release context, see the [Fast Preview docs](/docs/v4).
```

_{Reviews (1): Last reviewed commit: "docs(observability): remove v4 data mode..." | Re-trigger Greptile}

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Project	Deployment	Actions	Updated (UTC)
langfuse-docs	Ready	Preview, Comment	May 9, 2026 0:51am

[github-actions]

@claude review

[claude]

Author addressed the prior dangling anchor feedback by adding an explicit #under-the-hood anchor in v4.mdx, relocating the comparison table there, and repointing the FAQ link — clean docs reorg, LGTM.

Extended reasoning...

Overview

Docs-only PR that removes the "Underlying data model" H2 and table from content/docs/observability/data-model.mdx, relocates the comparison table to content/docs/v4.mdx under a new explicit #under-the-hood anchor, and repoints the only inbound link from content/faq/all/explore-observations-in-v4.mdx from the removed #underlying-data-model fragment to /docs/v4#under-the-hood.

Security risks

None — content-only MDX edits, no code, scripts, config, or auth surface touched.

Level of scrutiny

Low. The change is small, mechanical, and fully self-contained within three docs files. My prior deferral on this PR flagged a dangling anchor; the latest revision fixes it the right way (repoints the FAQ link AND ensures the destination has a stable explicit anchor that won't drift if the heading text is later edited).

Other factors

Verified the diff is internally consistent: the FAQ now links to /docs/v4#under-the-hood, and v4.mdx carries both the explicit [#under-the-hood] ID and the relocated comparison table. No other references to the removed #underlying-data-model anchor remain. Bug hunting system found no issues on this revision.