fix: suppress motion reports during a cmd-clicked link drag (follow-up to #74)

[austinywang]

Final follow-up to #71/#74 for manaflow-ai/cmux#5128.

#71 made Cmd-click open links under mouse reporting; #74 stopped the press/release of that click from leaking to a mouse-grabbing alt-screen TUI by suppressing the report whenever the ctrl/super link chord is held. This closes the last leak path: cursorPosCallback still emitted .motion reports while a button was held during the chord (it sees click_state == .press), so a slight drag during link activation leaked button-motion to the program.

Mirror the existing shift "grab override" for the ctrl/super chord in the motion-report path — suppressing only while a button is pressed, so pure movement reports are unaffected. With this, the link-activation chord suppresses the whole click+drag (press, release, and motion) consistently, matching iTerm2 / macOS Terminal.

zig fmt/ast-check clean. Behavior is integration-level (live Surface + mouse-reporting program), verified by cmux dogfood.

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AI disclosure (per AI_POLICY.md): developed with Claude Code (Claude Opus 4.8); reviewed by a maintainer.

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Summary by cubic

Prevent button-motion events from leaking to mouse-grabbing programs when cmd/super-clicking a link and dragging. The link-activation chord now suppresses press, release, and motion consistently, closing the last leak in manaflow-ai/cmux#5128.

• Bug Fixes
  • In cursorPosCallback, suppress motion while a button is pressed and the ctrl/super chord is held (mirrors the shift override). Pure movement without a pressed button is unaffected.

^{Written for commit 76ead3e. Summary will update on new commits.}

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

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Run ID: e3137aba-1add-4397-9e0f-2b718985d0c4

📥 Commits

Reviewing files that changed from the base of the PR and between 7850d70 and 76ead3e.

📒 Files selected for processing (1)

• src/Surface.zig

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix-5128-cmd-click-press-leak

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[greptile-apps]

Greptile Summary

This PR closes the last leak path from the ctrl/super link-activation chord by suppressing button-motion reports in cursorPosCallback while a mouse button is pressed during the chord — matching the existing shift "grab override" pattern that was already in place for shift-suppressed captures.

• Adds a 12-line guard in cursorPosCallback immediately after the analogous shift override: if self.mouse.mods exactly equals the ctrl/super chord and any button is not in the .release state, the motion report is suppressed via break :report.
• The check is intentionally unconditional (no mouseShiftCapture equivalent), consistent with the matching mouseButtonCallback check from fix: suppress mouse reporting for the full cmd-clicked link click (follow-up to #71) #74 and mouseLinkRefreshAllowedState, both of which also suppress unconditionally for the ctrl/super chord.

Confidence Score: 5/5

Safe to merge — the change is a surgical 12-line addition that closes a well-defined motion-report leak with no side-effects on unrelated code paths.

The guard mirrors the existing shift override character-for-character, uses self.mouse.mods that is already updated at the top of cursorPosCallback before this block runs, and is consistent with the unconditional ctrl/super suppression in mouseButtonCallback and mouseLinkRefreshAllowedState. Pure movement (no button held) is explicitly unaffected, and no existing behavior is touched.

No files require special attention.

Important Files Changed

Filename	Overview
src/Surface.zig	Adds a motion-suppression guard in cursorPosCallback for the ctrl/super chord — 12 lines mirroring the existing shift override exactly; logic, placement, and mod-comparison are consistent with the rest of the file.

Sequence Diagram

sequenceDiagram
    participant User
    participant Surface
    participant TUI as Mouse-grabbing TUI

    Note over User,TUI: Before this fix (ctrl/super held + button drag)
    User->>Surface: mouseButtonCallback (press, ctrl/super)
    Surface-->>TUI: "suppressed by #74"
    User->>Surface: cursorPosCallback (drag, button held)
    Surface->>TUI: motion report LEAKED

    Note over User,TUI: After this fix
    User->>Surface: mouseButtonCallback (press, ctrl/super)
    Surface-->>TUI: "suppressed (#74)"
    User->>Surface: cursorPosCallback (drag, button held, ctrl/super)
    Note over Surface: mods.equal(ctrlOrSuper) AND any state != .release
    Surface-->>TUI: suppressed (this PR)
    User->>Surface: cursorPosCallback (pure movement, no button held)
    Surface->>TUI: motion report sent (unaffected)
    User->>Surface: mouseButtonCallback (release, ctrl/super)
    Surface-->>TUI: "suppressed (#74)"

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