feat: Add agent tasks API support

[danyalahmed1995]

Summary

Adds typed client support for GitHub's Agent Tasks REST API.

This implements the documented public-preview Agent Tasks endpoints:

• GET /agents/repos/{owner}/{repo}/tasks
• POST /agents/repos/{owner}/{repo}/tasks
• GET /agents/repos/{owner}/{repo}/tasks/{task_id}
• GET /agents/tasks
• GET /agents/tasks/{task_id}

Closes #4213.

Changes

• Added AgentTasksService and registered it on Client.
• Added Agent Tasks request/response types for tasks, sessions, artifacts, list options, and create options.
• Added methods for listing, creating, and retrieving agent tasks.
• Added tests covering:
  • endpoint paths
  • HTTP methods
  • request bodies
  • response parsing
  • query parameters
  • pagination
  • preview API headers
• Added OpenAPI operation metadata for the new preview endpoints.
• Regenerated accessors and iterators.

Notes

The Agent Tasks API is currently in public preview, so this PR keeps the implementation scoped to the fields and endpoints currently documented by GitHub.

Validation

Ran the repository validation flow from CONTRIBUTING.md:

• script/fmt.sh
• script/test.sh ./...
• script/lint.sh
• script/generate.sh
• git diff --check

script/test.sh with the default race configuration could not run on this Windows machine because cgo/gcc was not available. I reran the full test script with the non-race fallback across all modules, and it passed.

[codecov]

Codecov Report

❌ Patch coverage is 97.93814% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.75%. Comparing base (40ed57f) to head (f8042ad).

Files with missing lines	Patch %	Lines
github/agent_tasks.go	96.42%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4225   +/-   ##
=======================================
  Coverage   97.75%   97.75%           
=======================================
  Files         189      190    +1     
  Lines       19035    19132   +97     
=======================================
+ Hits        18608    18703   +95     
- Misses        231      232    +1     
- Partials      196      197    +1     

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[gmlewis]

Thank you, @danyalahmed1995!
Just a couple tweaks/questions, then we should be ready for a second LGTM+Approval from any other contributor to this repo before merging.

cc: @stevehipwell - @alexandear - @zyfy29 - @Not-Dhananjay-Mishra - @munlicode

[danyalahmed1995]

@gmlewis Thanks, sounds good. I’ll address the review comments and push an update shortly.

[gmlewis]

Thank you, @danyalahmed1995!
LGTM.

cc: @stevehipwell - @alexandear - @zyfy29 - @Not-Dhananjay-Mishra - @munlicode

[stevehipwell]

Thanks for the PR @danyalahmed1995, I've added a couple of comments.

[danyalahmed1995]

@stevehipwell @alexandear updated, thanks for the reviews.

Changes in the latest update:

• adjusted the Agent Tasks response structs so documented required fields are non-pointers, while nullable/optional fields remain pointers
• folded the private list helper back into List and removed the Codecov-only List bad-options test so the production code stays simpler
• added agentTasksAPIVersion and replaced the repeated WithVersion("2026-03-10") usage
• updated the Agent Tasks doc comment URLs so the apiVersion value matches the request version
• regenerated the affected accessors/tests

Validation:

• script/generate.sh passed
• gofmt passed on changed Go files
• go test ./github passed
• script/fmt.sh passed
• script/test.sh ./... passed
• script/lint.sh passed
• git diff --check passed
• confirmed openapi_operations.yaml and go.mod have no diff
• confirmed changed files are LF-only with no CRLF churn

[stevehipwell]

It looks like the generator might be overwriting the API version?

[danyalahmed1995]

Oh yeah good catch it's possible. I’ll check whether the generator is rewriting those doc comment URLs and update the source of that version instead of just manually editing the generated comments.