Fix terminal file drops inserting paths

[austinywang]

Summary

• Restore terminal file drops to the file-path insertion path by refusing inactive terminal pane drop targets.
• Add a regression test for the portal lookup invariant that let viewer-oriented pane routing shadow terminal text insertion, with both active-context and cleared-context assertions.

Local repro

1. On current main, construct a GhosttySurfaceScrollView and install an active TerminalPaneDropContext.
2. Query paneDropTargetForDrop(at:) at the center of the hosted terminal; active pane routing is available.
3. Clear the pane drop context with setPaneDropContext(nil), mirroring a stale/inactive terminal portal lookup during a Finder file drop.
4. Observed on the failing regression commit: lookup still returns a TerminalPaneDropTargetView, even though that target cannot handle the drop because its context is nil. This can route the file drop toward the built-in preview path instead of terminal text insertion.
5. Expected: lookup returns nil after context is cleared, allowing terminal file-path insertion to receive the drop.

Commits

• 47b730493 adds the failing regression test only.
• 6d13e2b09 applies the fix.

Testing

• Not run locally by request; direct xcodebuild/local test execution is intentionally avoided before CI.
• CI/CD is being driven with $iterate-pr until fully green.

Closes #3729

---

Note

Low Risk
Low risk: a small guard condition changes drop-target discovery only when dropContext is nil, plus a focused regression test to lock the behavior in.

Overview
Fixes Finder file drops being misrouted by making paneDropTargetForDrop(at:) return nil unless paneDropTargetView.dropContext is set, so inactive pane-drop targets no longer shadow file-path insertion.

Adds a regression test ensuring drop-target lookup succeeds with an active context and returns nil after setPaneDropContext(nil).

^{Reviewed by Cursor Bugbot for commit 6d13e2b. Bugbot is set up for automated code reviews on this repo. Configure here.}

Summary by CodeRabbit

• Bug Fixes

  • Prevented inactive/no-drop contexts from participating in drop hit-testing so they no longer interfere with file-path drop insertion.

• Tests

  • Added a test ensuring drop target lookup returns no target when the drop context is inactive, guarding against accidental drop handling.

[vercel]

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Project	Deployment	Actions	Updated (UTC)
cmux	Canceled		May 12, 2026 3:44am
cmux-staging	Building	Preview, Comment	May 12, 2026 3:44am

[coderabbitai]

📝 Walkthrough

Walkthrough

A guard in GhosttySurfaceScrollView.paneDropTargetForDrop(at:) now returns nil when the pane drop target view's dropContext is nil, preventing hit-testing and selection; a regression test verifies the lookup returns nil after clearing the drop context.

Changes

Drop-target detection guard

Layer / File(s)	Summary
Drop-target context guard and validation Sources/GhosttyTerminalView.swift, cmuxTests/TerminalAndGhosttyTests.swift	Added an early-return guard in paneDropTargetForDrop(at:) to skip drop-target detection when paneDropTargetView.dropContext is nil. Added testTerminalPaneDropTargetLookupRequiresActiveDropContext which sets a non-nil drop context and verifies paneDropTargetForDrop(at:) returns a target, then clears the context, forces layout, and asserts the lookup returns nil.

Estimated Code Review Effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly Related PRs

• manaflow-ai/cmux#1717: Touches terminal/ghostty drop-target behavior and related tests.
• manaflow-ai/cmux#1213: Modifies GhosttySurfaceScrollView drop/overlay and drop-context lifecycle logic.
• manaflow-ai/cmux#3299: Related changes to TerminalPaneDropTargetView and dropContext checks.

Poem

🐰 I hopped to the gate where the droppings lie,
If context is missing, I pass them by,
No phantom targets to trip the display,
The terminal keeps its rightful way,
Tests nod and nibble — hip hop, hooray!

🚥 Pre-merge checks | ✅ 14 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (14 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'Fix terminal file drops inserting paths' accurately describes the main change: restoring terminal file drops to use the file-path insertion path instead of being misrouted to the built-in viewer.
Linked Issues check	✅ Passed	The PR directly addresses #3729 by adding a guard to prevent inactive pane drop targets from intercepting file drops, allowing terminal file-path insertion to receive drops as intended.
Out of Scope Changes check	✅ Passed	All changes are scoped to the drag-and-drop regression fix: one guard condition in the drop-target discovery and a focused regression test verifying the expected behavior.
Cmux Swift Actor Isolation	✅ Passed	Production code change adds a guard nil-check to a MainActor-inherited NSView method. No new types, Sendable violations, or background context access introduced. Test file excluded per check rules.
Cmux Swift Blocking Runtime	✅ Passed	No blocking patterns introduced. Production code adds a simple guard check. Test uses deterministic scaffolding without sleep or timing delays. Complies with swift-blocking-runtime.md rules.
Cmux No Hacky Sleeps	✅ Passed	PR only modifies Swift files. The check explicitly states: "Swift timing and blocking primitives are covered by swift-blocking-runtime.md." Therefore, this PR is outside the scope of this check.
Cmux Swift Concurrency	✅ Passed	Adds a synchronous guard and XCTest without legacy concurrency patterns. No DispatchQueue, Combine, completion handlers, or Tasks.
Cmux Swift @Concurrent	✅ Passed	PR adds a synchronous guard check in paneDropTargetForDrop() with no async/await, @concurrent annotations, or heavy operations. All changes comply with swift-concurrent-annotation.md rules.
Cmux Swift File And Package Boundaries	✅ Passed	Adds 1-line guard to paneDropTargetForDrop method and 27-line regression test. Focused bug fix; small AppKit glue code. Test code allowed per rules. Preserves single responsibility.
Cmux Swift Logging	✅ Passed	All logging in the PR complies with Swift logging rules. Debug logging is properly guarded by #if DEBUG, and no unguarded print/NSLog statements exist in production code.
Cmux Swiftui State Layout	✅ Passed	No new @Published/@Observable/@State patterns. Changes only in NSView subclass (AppKit), which is allowed per rules for bridge views not owned by SwiftUI.
Cmux Architecture Rethink	✅ Passed	Small correctness fix. Adds single guard requiring active dropContext in paneDropTargetForDrop. No prohibited patterns. Clear owner and invariant. Includes regression test.
Cmux Swift Auxiliary Window Close Shortcuts	✅ Passed	PR modifies terminal pane helper views (NSView subclasses), not standalone windows. No NSWindow, NSPanel, or WindowGroup created. Test additions are in test-only fixtures.
Description check	✅ Passed	The PR description is comprehensive and well-structured, covering all required sections from the template: summary, local reproduction steps, commits, and testing approach.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch issue-3729-dnd-restore-path-insert

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[greptile-apps]

Greptile Summary

This PR fixes a drag-and-drop routing bug where GhosttySurfaceScrollView.paneDropTargetForDrop(at:) would return a TerminalPaneDropTargetView even when its dropContext was nil, causing Finder file drops to be misrouted toward the built-in preview path instead of terminal text insertion.

• Production fix: A single guard paneDropTargetView.dropContext != nil else { return nil } line added at the top of paneDropTargetForDrop(at:) ensures inactive targets are invisible to drop hit-testing.
• Regression test: testTerminalPaneDropTargetLookupRequiresActiveDropContext now covers both the positive path (active context → non-nil result) and the negative path (nil context → nil result), fully pinning the invariant against future regressions.

Confidence Score: 5/5

Safe to merge — the guard is a minimal, correctly ordered early exit with no side effects on any path other than the broken nil-context one.

The production change is a single guard line that short-circuits an existing function only when dropContext is already nil; it cannot affect pane drop routing when a real context is present. The regression test now covers both the active-context and cleared-context paths, making the fix observable and falsifiable. No concurrency, state, or architectural concerns are introduced.

No files require special attention.

Important Files Changed

Filename	Overview
Sources/GhosttyTerminalView.swift	Adds a one-line nil-context guard to paneDropTargetForDrop(at:); fix is minimal, correctly ordered, and closes the drop-routing shadow bug.
cmuxTests/TerminalAndGhosttyTests.swift	Adds a regression test covering both active-context (non-nil) and cleared-context (nil) paths, making the guard's effect observable and the test falsifiable.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["Finder file drop"] --> B["paneDropTargetForDrop(at:)"]
    B --> C{"dropContext != nil"}
    C -- "false — NEW GUARD" --> D["Return nil → terminal text insertion"]
    C -- "true" --> E{"bounds check"}
    E -- "fail" --> D
    E -- "pass" --> F{"converted point check"}
    F -- "fail" --> D
    F -- "pass" --> G{"shouldDeferToPaneTabBar"}
    G -- "true" --> D
    G -- "false" --> H["Return TerminalPaneDropTargetView → pane routing"]

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