Fix terminal drag hover overlay flicker - #1050

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Project	Deployment	Actions	Updated (UTC)
cmux	Ready	Preview, Comment	Mar 7, 2026 7:37pm

No actionable comments were generated in the recent review. 🎉

sequenceDiagram
    participant Host as GhosttyTerminalView
    participant Registry as TerminalWindowPortalRegistry
    participant Hosted as HostedView/Surface

    Host->>Registry: isHostedView(hostedView)?
    Registry-->>Host: returns portalEntryMissing (true/false)
    alt portalEntryMissing == true
        Host->>Registry: bind(host, hostedView)  rgba(100,150,240,0.5)
        Registry-->>Hosted: establish portal entry  rgba(100,200,150,0.5)
        Registry-->>Host: confirm bound
    else portalEntryMissing == false
        Host->>Hosted: continue existing binding flow
    end

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Greptile Summary

This PR advances the vendor/bonsplit submodule pointer from b1f4916 (the restored SafeTooltip base that was re-established after reverting PR #1046) to fa452db, which is described as the repaired overlay commit. The single-file diff is a clean re-land of issue #1045 following the revert/re-apply workflow visible in the git history (e019293 → revert eaa7647 → this landing 62125c1).

• Submodule update only — the diff is a one-line pointer change in vendor/bonsplit; all substantive code lives in the bonsplit package itself
• Bonsplit is consumed as an XCLocalSwiftPackageReference in GhosttyTabs.xcodeproj, pointing at vendor/bonsplit; no Package.resolved entry is expected or required for local packages, and none was changed
• TerminalPanelView.swift already carries .id(panel.id) to keep the NSViewRepresentable identity stable across bonsplit structural updates (comment: "Keep the NSViewRepresentable identity stable across bonsplit structural updates"), so the cmux-side geometry-stability measure pre-dates this PR
• Re-land history is consistent: git submodule status confirms the working tree is at fa452db181f361514087558a29204bda7e38218f, matching the pointer written by this commit

Confidence Score: 4/5

• Safe to merge; the change is a single submodule pointer bump with a well-documented revert-and-re-land history and confirmed bonsplit CI passage.
• The diff is minimal (one submodule pointer line), the re-land workflow is traceable in git history, the Xcode project wiring for the local package is unchanged and correct, and Package.resolved correctly omits local packages. The only reason this is not a 5 is that the internal bonsplit changes (overlay rendering, geometry-stability fix, regression test) are not directly reviewable from this repository — reviewers must trust bonsplit's own CI and the PR description.
• No files require special attention beyond the bonsplit submodule itself, which should be reviewed at the bonsplit repo level.

Important Files Changed

Sequence Diagram

sequenceDiagram
    participant User
    participant cmux (SwiftUI)
    participant BonsplitLayout
    participant TerminalPanelView
    participant GhosttyTerminalView (NSView)

    User->>BonsplitLayout: Drag tab over pane
    Note over BonsplitLayout: OLD: drop-zone indicator shifted<br/>hosted content bounds → resize event fired
    BonsplitLayout-->>GhosttyTerminalView (NSView): Frame changed → terminal relayout + flicker

    Note over BonsplitLayout: NEW (fa452db): drop-zone rendered<br/>as true overlay, hosted content<br/>geometry unchanged
    User->>BonsplitLayout: Drag tab over pane
    BonsplitLayout->>TerminalPanelView: Geometry stable (no frame change)
    TerminalPanelView->>GhosttyTerminalView (NSView): No resize event emitted → no flicker

_{Last reviewed commit: 62125c1}