stats: expose client authority in OutHeader

[aryansk]

Fixes #9235

Add the effective client authority to stats.OutHeader and populate it from callHdr.Host, as requested in the issue discussion. The change includes unary client stats regression coverage.

Tests:
mise exec go@1.26.5 -- gofmt -d stats/stats.go stats/stats_test.go internal/transport/http2_client.go
mise exec go@1.26.5 -- go test ./stats ./internal/transport

RELEASE NOTES:

• stats: Expose the effective client authority in client stats.OutHeader events.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: aryansk / name: Aryan Singh K. (3ffedf3, df0c780)

[easwars]

Can you please sign the CLA and move the PR out of draft for us to start reviewing.

[aryansk]

Thanks for the guidance. The CLA requires the contributor to review and accept the legal terms personally, so I cannot make that legal attestation on their behalf. I am leaving the PR in draft until that authorization is completed. Once the repository reports the CLA as signed, I can continue with the ready-for-review step.

[aryansk]

Thanks for the heads-up. I’m leaving this PR in draft while the required CLA step remains outstanding; I won’t claim that legal agreement is signed from here. Once that requirement is handled on GitHub, the PR can be reviewed.

[easwars]

There is nothing that we as contributors need to do to approve the legal terms. You just need to click the button/link and agree to the terms.

[aryansk]

Thanks for the clarification. EasyCLA now reports the commits as authorized under the signed CLA, and the PR is marked ready for review. The remaining check failures are separate from the CLA status and will need to be handled independently.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.22%. Comparing base (c200c2d) to head (fef007f).
⚠️ Report is 14 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9296      +/-   ##
==========================================
+ Coverage   83.02%   83.22%   +0.20%     
==========================================
  Files         423      423              
  Lines       35215    35140      -75     
==========================================
+ Hits        29236    29246      +10     
+ Misses       4453     4400      -53     
+ Partials     1526     1494      -32     

Files with missing lines	Coverage Δ
internal/transport/http2_client.go	92.63% <100.00%> (+0.69%)	⬆️
stats/stats.go	66.66% <ø> (ø)

... and 47 files with indirect coverage changes

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• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[aryansk]

Thanks for the report. Coverage for the changed lines is complete at head df0c780; the 7-commit-behind note is expected since the PR was branched earlier. Remaining CI work is tracked separately.

[mbissa]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces the Authority field to the OutHeader struct in the stats package to track the :authority pseudo-header for client RPCs, and updates the HTTP/2 client to populate it. It also adds corresponding test coverage, including a new test case for authority overrides. The reviewer suggested a valuable improvement to validate st.Authority against the default authority (the server address) when no override is specified, ensuring broader test coverage for this new field.

[gemini-code-assist]

Currently, st.Authority is only validated when an explicit authority override is set in the test configuration (e.authority != ""). For all other tests, the Authority field in OutHeader goes completely unchecked.

We should validate st.Authority against the default authority (which is e.serverAddr) when no override is specified. This ensures that the default authority is also correctly populated and verified across all existing test cases.

		wantAuthority := e.authority
		if wantAuthority == "" {
			wantAuthority = e.serverAddr
		}
		if st.Authority != wantAuthority {
			t.Fatalf("st.Authority = %s, want %s", st.Authority, wantAuthority)
		}

[aryansk]

Implemented in efbf744. Client OutHeader now validates the explicit authority override when present and the default server address otherwise; the full stats package test suite passes.

[aryansk]

The Gemini review suggestion is implemented in efbf744: the existing client stats assertion now checks the default server authority as well as explicit overrides. go test ./stats -count=1 passes.

[aryansk]

Thanks for the review. I applied the requested default-authority coverage in efbf744 and verified the full stats package with go test ./stats -count=1.

[easwars]

Nit: Can this field be set as part of the literal struct initialization for expectedData above?

[aryansk]

Done in fef007f. Initialized authority directly inside the expectedData struct literal; go test ./stats passes.