Update CI matrix to test Node.js 26 and fix diagnostics compatibility

[Copilot]

The CI workflow was still testing Node.js 25 in the cross-platform test matrix. This updates the matrix to track Node.js 26 and includes the compatibility fix needed for the diagnostics tests to pass on Node.js 26.

• CI matrix

  • Replaced 25 with 26 in .github/workflows/nodejs.yml
  • Keeps the existing OS coverage unchanged while moving the Node.js version set forward

• Node 26 diagnostics compatibility

  • Updated HttpClient to use a dedicated undici Agent by default instead of relying on the global dispatcher
  • Adjusted test/diagnostics_channel.test.ts to ignore diagnostics events that do not include handler opaque state

• Scope

  • Includes a small runtime compatibility fix plus targeted test updates
  • No package metadata changes

strategy:
  matrix:
    os: ['ubuntu-latest', 'macos-latest', 'windows-latest']
    node: ['22', '24', '26']

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/node-modules/urllib@762

commit: ce8ed51

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/node-modules/urllib@762

commit: 754babc

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.65%. Comparing base (cea1cd7) to head (754babc).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #762   +/-   ##
=======================================
  Coverage   94.65%   94.65%           
=======================================
  Files          10       10           
  Lines         730      730           
  Branches      228      228           
=======================================
  Hits          691      691           
  Misses         36       36           
  Partials        3        3           

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[fengmk2]

@copilot ci fails

[Copilot]

@copilot ci fails

Fixed in ce8ed51. I investigated the failing Node 26 jobs, updated the default HttpClient dispatcher path to avoid the global undici dispatcher on Node 26, and tightened the diagnostics-channel tests so they ignore events without handler opaque state. Targeted diagnostics tests now pass on both Node 22 and Node 26 locally.