fix(layout): exclude Dagre endpoints from control points

[dvd233]

Fixes #7671.

Dagre includes node-boundary endpoints in edge.points. Passing these through as control points duplicates the rendered endpoints, leaving a zero-length end tangent and incorrect arrow orientation.

Exclude those endpoints only for Dagre, preserving AntVDagre/custom-layout output and the raw layout data. Add regressions for all four rank directions, missing/empty points, and input immutability.

Validation:

• The four Dagre regressions fail before the fix and pass afterward.
• Core Jest: 217 suites pass, 700 tests pass, 2 tests skipped by an existing it.only in camera-setting.spec.ts (Ubuntu, Node 22, native SWC). Changed statements and branches are fully covered.
• Core ESLint, Prettier, TypeScript, CJS/ESM/UMD builds and bundle size checks pass (Windows, Node 20).
• Chromium verifies aligned arrows and nonzero end tangents for all 12 edges across LR/RL/TB/BT, using the built UMD. The original example's unregistered drag-node warning remains; this probe covers the initial static layout.

Before (LR)	After (LR)

[hustcc]

@dvd233 是不是应该在 layout 库修复这个问题？

[dvd233]

我倾向于先在 G6 的适配层处理：Dagre 的 edge.points 表示包含节点边界端点的完整折线，而 G6 的 controlPoints 只应包含中间点，渲染时会自行补端点。直接传入会重复端点，导致末端切线为零；这不一定是 layout 的完整折线输出有误。这个补丁仅在 Dagre → G6 controlPoints 的转换中取 slice(1, -1)，不修改原始 layout 结果，也不改变 AntVDagre/custom layout 的行为，避免影响其他直接消费完整 points 的调用方。四个方向的回归均已验证先失败后通过，浏览器里 12 条边的末端切线和箭头方向也已核对。这里的选择基于上述两层数据契约，最终修复位置请维护者确认。

[Copilot]

🟢 Approval recommended

The narrow fix matches endpoint rendering behavior, has focused regression coverage, and has no unresolved findings.

0 open findings

What changed in this PR

Fixes Dagre edge arrow orientation by excluding node-boundary endpoints from rendered control points, addressing #7671.

Changes:

• Removes endpoints only for Dagre, preserving other layouts and raw layout data.
• Adds regressions for all four rank directions, missing/empty points, and input immutability.

File	Description
packages/​g6/​src/​utils/​layout.ts	Excludes Dagre endpoints from control points.
packages/​g6/​__tests__/​unit/​utils/​layout.spec.ts	Adds regression and compatibility coverage.

🧠 Review effort: Balanced

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.43%. Comparing base (e825d09) to head (a1666a1).
⚠️ Report is 1 commits behind head on v5.

Additional details and impacted files

@@           Coverage Diff           @@
##               v5    #7687   +/-   ##
=======================================
  Coverage   94.43%   94.43%           
=======================================
  Files         188      188           
  Lines       10099    10101    +2     
  Branches     2152     2153    +1     
=======================================
+ Hits         9537     9539    +2     
  Misses        516      516           
  Partials       46       46           

Flag	Coverage Δ
g6	94.43% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
packages/g6/src/utils/layout.ts	66.66% <100.00%> (+0.45%)	⬆️

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