fix(forkchoice-viz): always render finalized block as fully filled

[conache]

🗒️ Description / Motivation

The fork choice visualization currently renders the finalized block as empty. This happens because each node is filled proportionally to its weight value. This value is computed by the compute_block_weights() method, which returns 0 for the start_slot (which is always the finalized block's slot).

The reported 0 is technically accurate but misleading: a finalized block has full validator support by definition (2/3 supermajority and unbroken justified chain). However, this is only misleading for the visualisation, since compute_block_weights() correctly skips the finalized block because LMD GHOST treats it as the root of the fork-choice tree, not a candidate, so weighing it adds no information to head selection.

Proposed solution: render finalized blocks as fully filled green discs and show status: finalized in the tooltip instead of weight: 0.

What Changed

• crates/net/rpc/static/fork_choice.html:
• nodeRatio: returns 1 for blocks at or below finalized.slot, so they render as solid green discs.
• Tooltip shows status: finalized for finalized blocks instead of weight: 0.

Correctness / Behavior Guarantees

• Only the forkchoice visualization changes; consensus and weight computation are unchanged.
• Non-finalized blocks still fill proportionally to weight / validator_count.
• Finalized blocks show up as fully filled. When hovering on a finalized block, there's a status field associated showing: status: finalized.

Tests Run

• Manual: ran a single-node devnet and confirmed finalized blocks render as solid green discs with status: finalized in the tooltip.

Related Issues / PRs

• Closes Fork choice viz: finalized node shows 0 weight #333

[greptile-apps]

Greptile Summary

This PR updates the fork-choice visualization so that finalized blocks render as fully filled green discs and display status: finalized in their tooltip, instead of showing weight: 0. All changes are confined to fork_choice.html; consensus and weight-computation logic are untouched.

• _stroke computed but unused: nodeStroke and the _stroke property are introduced, but the .node-outer circle still reads d._color for its stroke on both enter and update — the intended darker outline never renders.
• Tooltip regression: non-finalized blocks silently lose the weight/total (pct%) breakdown that was present before this PR.

Confidence Score: 3/5

Safe to merge with reservations — a newly introduced visual feature (_stroke darker outline) is silently inert, and non-finalized tooltip information is regressed.

One P1 (dead _stroke feature that never applies) and two P2s (tooltip regression, redundant guard) pull the score below the P1 ceiling of 4.

crates/net/rpc/static/fork_choice.html — specifically the _stroke wiring in the .node-outer enter/update blocks and the tooltip weight percentage.

Important Files Changed

Filename	Overview
crates/net/rpc/static/fork_choice.html	Visualization-only change: finalized blocks now render as fully filled green discs with "status: finalized" tooltip; introduces _stroke (computed but never applied to the outer circle), drops weight percentage from non-finalized tooltips, and contains a redundant guard in nodeRatio.

Comments Outside Diff (1)

1. crates/net/rpc/static/fork_choice.html, line 229-230 (link)

   Redundant guard in nodeRatio

   !validatorCount already returns true when validatorCount is 0 (since !0 === true), so the || validatorCount === 0 branch is unreachable dead code.

   Prompt To Fix With AI

   This is a comment left during a code review.
   Path: crates/net/rpc/static/fork_choice.html
   Line: 229-230
   
   Comment:
   **Redundant guard in `nodeRatio`**
   
   `!validatorCount` already returns `true` when `validatorCount` is `0` (since `!0 === true`), so the `|| validatorCount === 0` branch is unreachable dead code.
   
   
   
   How can I resolve this? If you propose a fix, please make it concise.

Prompt To Fix All With AI

Fix the following 3 code review issues. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 3
crates/net/rpc/static/fork_choice.html:322
**`_stroke` is computed but never applied**

`_stroke` is stored on each flat node but the render code references `d._color` for both the initial enter and the transition update of `.node-outer`. The `nodeStroke` function (and this property) are therefore dead code — the darker outline never actually appears.

### Issue 2 of 3
crates/net/rpc/static/fork_choice.html:229-230
**Redundant guard in `nodeRatio`**

`!validatorCount` already returns `true` when `validatorCount` is `0` (since `!0 === true`), so the `|| validatorCount === 0` branch is unreachable dead code.

```suggestion
      if (!validatorCount) return 0;
```

### Issue 3 of 3
crates/net/rpc/static/fork_choice.html:350-356
**Non-finalized tooltip silently drops the weight percentage**

The old tooltip rendered `weight: X/total (pct%)` for non-finalized blocks; the new version shows only `weight: X`. The `total` and percentage were useful for understanding a node's relative support — this is a quiet regression for all non-finalized nodes in the tree.

_{Reviews (1): Last reviewed commit: "Completely fill the finalized block node..." | Re-trigger Greptile}

[greptile-apps]

_stroke is computed but never applied

_stroke is stored on each flat node but the render code references d._color for both the initial enter and the transition update of .node-outer. The nodeStroke function (and this property) are therefore dead code — the darker outline never actually appears.

Prompt To Fix With AI

This is a comment left during a code review.
Path: crates/net/rpc/static/fork_choice.html
Line: 322

Comment:
**`_stroke` is computed but never applied**

`_stroke` is stored on each flat node but the render code references `d._color` for both the initial enter and the transition update of `.node-outer`. The `nodeStroke` function (and this property) are therefore dead code — the darker outline never actually appears.

How can I resolve this? If you propose a fix, please make it concise.

[greptile-apps]

Non-finalized tooltip silently drops the weight percentage

The old tooltip rendered weight: X/total (pct%) for non-finalized blocks; the new version shows only weight: X. The total and percentage were useful for understanding a node's relative support — this is a quiet regression for all non-finalized nodes in the tree.

Prompt To Fix With AI

This is a comment left during a code review.
Path: crates/net/rpc/static/fork_choice.html
Line: 350-356

Comment:
**Non-finalized tooltip silently drops the weight percentage**

The old tooltip rendered `weight: X/total (pct%)` for non-finalized blocks; the new version shows only `weight: X`. The `total` and percentage were useful for understanding a node's relative support — this is a quiet regression for all non-finalized nodes in the tree.

How can I resolve this? If you propose a fix, please make it concise.