Investigate and try to fix 'bonkers' lane handling when inserting blank commit

[Byron]

Best shown in a video.

But in short, the lanes are completely shuffled around, and as the algorithm to handle these shouldn't have changed, I assume the vb.toml file is fixed up incorrectly. Turns out that assumption was false though.

Screen_Recording_2026-01-24_at_10.50.52.mov

Here is the commit that introduces the insert-blank-commit issue:
5980d99

Tasks

• investigate what's causing this
  • It's not reconciliation
  • bisect - the problem starts here: 5980d99
• fix it - wait for @Caleb-T-Owens who can probably fix it faster/better
  • Note that cargo run --bin but-testing -- -C /test-repo graph shows the worktree metadata, which also changes in unexpected ways.

Research

Disable reconciliation of metadata

This didn't have any effect.

diff --git a/crates/but-meta/src/legacy.rs b/crates/but-meta/src/legacy.rs
index 0ea7982847..30a47095b8 100644
--- a/crates/but-meta/src/legacy.rs
+++ b/crates/but-meta/src/legacy.rs
@@ -185,6 +185,7 @@ impl Snapshot {
 
     #[instrument(level = "debug", skip(self, repo))]
     fn reconcile_and_fix_vb_toml(&mut self, repo: &gix::Repository) -> anyhow::Result<()> {
+        return Ok(());
         fn make_heads_match(ws_stack: &but_graph::projection::Stack, vb_stack: &mut Stack) -> bool {
             // Always leave extra segments.
 

[Copilot]

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[vercel]

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