refactor(editor): move canvas pointer handlers to src/mouse.js (R2, step 34)

[byrongamatos]

What

Step 34 of the R2 module-extraction refactor: move the canvas pointer event handlers out of src/main.js into a new native ES module src/mouse.js.

getMousePos + onMouseDown / onMouseMove / _onMouseMoveBody / onMouseUp / onDblClick / onWheel — the drag/select/inline-edit, double-click-add, and wheel zoom/scroll dispatchers.

How the seam is drawn

The "Mouse interactions" banner is a 2,015-line grab-bag (pointer handlers + keyboard-command layer + tab-preview + shortcut-panel + onContextMenu). This step takes the genuinely-pointer core (595 lines); the rest are separate concerns left in main.js for their own later steps.

• src/mouse.js: 17 module imports (the pointer core touches most of the graph), 6 handlers exported back — main.js's init() attaches them to the canvas; getMousePos remains a host hook, now sourced here.
• 4 new host hooks for the composition-root symbols the handlers call: showAddNote, updateZoomDisplay, partsViewOnMouseDown, partsViewOnDblClick.
• Removed 31 now-dead main.js imports (used only by the moved pointer code) — the strict no-undef gate confirmed no over-removal.
• tests/keyboard_gutter_dblclick.test.mjs retargeted to slice onDblClick from mouse.js and inject a host stub (onDblClick now reaches showAddNote / partsViewOnDblClick through host).

main.js drops ~595 lines. 35 modules.

Verification

• 90/90 JS suites pass; ESLint gate clean (0 errors); strict no-undef clean on mouse.js.
• Codex preflight: 0 correctness issues.
• New headless harness (verify_mouse.py) drives real pointer events: ctrl+wheel zooms the readout (100→138%, proving host.updateZoomDisplay), clicking a note selects it and reveals the inspector, double-clicking empty grid opens the add-note dialog (proving host.showAddNote), and dragging a note moves it (proving host.draw) — zero page errors. Both new hooks negative-checked.

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features
  • Expanded canvas interactions with full support for clicking, dragging, rectangular selection, zooming, panning, and mode-aware double-click actions.
  • Enhanced host integration to support showing add-note UI, updating zoom display, and handling Parts-view mouse down/double-click.
• Bug Fixes
  • Ensured double-click in the keyboard gutter no longer triggers add-note, while double-click in the note area still does.
• Refactor
  • Consolidated mouse and pointer interaction logic into a dedicated interaction module.
• Tests
  • Updated the keyboard gutter double-click regression test to match the new interaction path.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 4d8168fb-3e45-4de4-8595-f607b454f923

📥 Commits

Reviewing files that changed from the base of the PR and between e480d6e and 7d96355.

📒 Files selected for processing (1)

• src/mouse.js

---

📝 Walkthrough

Walkthrough

The PR extracts editor mouse interactions from src/main.js into src/mouse.js, adds host callbacks for note, zoom, and Parts-view interactions, and updates the keyboard-gutter double-click regression test.

Changes

Mouse interaction refactor

Layer / File(s)	Summary
Dedicated mouse interaction module src/mouse.js	Adds coordinate conversion and handlers for mouse clicks, dragging, double-clicks, zooming, panning, note editing, lane interactions, and selection behavior.
Main integration and host callbacks src/main.js, src/host.js	Imports the extracted handlers, removes their previous implementations, and exposes the new host callbacks.
Double-click regression coverage tests/keyboard_gutter_dblclick.test.mjs	Updates callback extraction and dependency wiring to test onDblClick from src/mouse.js.

Estimated code review effort: 4 (Complex) | ~45 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Canvas
  participant MouseHandlers
  participant EditorState
  participant Commands
  Canvas->>MouseHandlers: Send mouse, double-click, or wheel event
  MouseHandlers->>EditorState: Update drag, selection, zoom, or note state
  MouseHandlers->>Commands: Commit note or sustain changes on mouse up

Loading

Possibly related PRs

• got-feedBack/feedBack-plugin-editor#155: Both changes affect the keyboard-gutter double-click path and its regression tests.
• got-feedBack/feedBack-plugin-editor#168: Both changes modify the shared host callback wiring in src/host.js and src/main.js.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 11.11% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: moving canvas pointer handlers into src/mouse.js.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ 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 refactor/r2-step34-mouse

---

_{Comment @coderabbitai help to get the list of available commands.}

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/mouse.js`:
- Line 434: Remove the unused x destructuring in onMouseUp, retaining only the y
value returned by getMousePos(e); verify both select and move branches continue
using their existing coordinates correctly.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 045074af-0482-433d-87ab-d0837077680c

📥 Commits

Reviewing files that changed from the base of the PR and between 7a0f8a7 and e480d6e.

📒 Files selected for processing (4)

• src/host.js
• src/main.js
• src/mouse.js
• tests/keyboard_gutter_dblclick.test.mjs