fix(desktop): unlink zoom mode references on split and support direct canvas point positioning

[massmarketconsumer-arch]

Summary

Resolves #2230

Problem

When a user splits a zoom segment into two and adjusts the new split zoom segment in the editor, the platform continued zooming into the original area (or adjustments affected both segments). This was caused by:

1. splitZoomSegment shallow-copying segment ({ ...segment }), causing both zoom segments to share the exact same mode object reference in memory. Mutating the mode on one segment mutated both segments.
2. In ZoomSegmentConfig, mouse drag called setProject("timeline", "zoomSegments", props.segmentIndex, "mode", "manual", { x, y }). In Solid Store, attempting to set property manual on a string primitive throws TypeError: Cannot create property 'manual' on string 'auto', preventing coordinates from updating when switching modes.
3. In ZoomSegmentConfig, onMouseDown on the preview canvas only attached mousemove/mouseup listeners without immediately setting the position on click, requiring the user to drag to register any change.

Solution

1. Extracted splitZoomSegmentsList with cloneZoomMode helper in apps/desktop/src/routes/editor/zoom.ts to ensure each split segment owns an isolated mode configuration.
2. Updated ZoomSegmentConfig to safely replace the entire mode object ({ manual: { x, y } }) and handle click-to-position on mouse down in addition to drag.
3. Added unit test suite apps/desktop/src/routes/editor/zoom.test.ts verifying zoom segment split independence and boundary enforcement.

Confidence Score: 4/5

The behavior appears correct, but the explicit repository comments requirement must be satisfied before merging.

Findings

1.  Redundant Test Comments ▶

Fix with agent prompt

### Issue 1
apps/desktop/src/routes/editor/zoom.test.ts:40
The comment repeats what the following reference-identity assertions already express. This violates the repository directive to avoid comments that merely narrate the code. Remove it and the similar comment before the mutation-independence assertion on line 51. This repository requirement must be satisfied before merging.

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

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For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

Summary

• Extracts and tests zoom-segment split logic, including minimum-duration boundaries and mode-reference independence.
• Supports direct click positioning as well as dragging on the preview canvas.
• Preserves existing split-time and segment-ordering behavior.
• Contains redundant test comments that conflict with the repository’s explicit comments policy.

_{Reviews (1) · Last reviewed commit: "fix(desktop): unlink zoom mode reference..."}

[greptile-apps]

Redundant test comments

The comment repeats what the following reference-identity assertions already express. This violates the repository directive to avoid comments that merely narrate the code. Remove it and the similar comment before the mutation-independence assertion on line 51. This repository requirement must be satisfied before merging.

Context Used: CLAUDE.md (source)

Prompt To Fix With AI

This is a comment left during a code review.
Path: apps/desktop/src/routes/editor/zoom.test.ts
Line: 40

Comment:
**Redundant test comments**

The comment repeats what the following reference-identity assertions already express. This violates the repository directive to avoid comments that merely narrate the code. Remove it and the similar comment before the mutation-independence assertion on line 51. This repository requirement must be satisfied before merging.

**Context Used:** CLAUDE.md ([source](https://github.com/capsoftware/cap/blob/main/CLAUDE.md))

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

[massmarketconsumer-arch]

Fixed in 212781d. Removed redundant explanatory comments before reference-identity assertions to comply with repository comment guidelines.