Move HeaderForward helpers to pkg/vmcp/headerforward

[lorr1]

Summary

• Why: PR Wire HeaderForward into vMCP per-session HTTP client #5301 exported BuildHeaderForwardTripper from pkg/vmcp/client/ so the per-session HTTP client at pkg/vmcp/session/internal/backend/ could reuse it without duplicating ~160 LOC of transport-chain construction. That export was the minimum-viable fix for MCPServerEntry.headerForward.addPlaintextHeaders is silently ignored — never reaches upstream #5289, but pkg/vmcp/client/ is also a consumer of the helper — not its logical home. Two consumers + an awkwardly placed shared helper is one of the shapes vMCP anti-pattern Start simple hardcoded registry #8 calls out.
• What: Lift the helper into its own sibling package pkg/vmcp/headerforward/. The companion subpackage pkg/vmcp/headerforward/wirefmt/ already exists, so the namespace is established. Pure mechanical move — no signature change, no behavior change, existing tests still cover the helper end-to-end.

Related to #5289.

Type of change

• Refactoring (no behavior change)
• Bug fix
• New feature
• Dependency update
• Documentation
• Other (describe):

Test plan

• Unit tests (task test) — existing BuildHeaderForwardTripper and resolveHeaderForward tests moved alongside the helper, still pass against the new location.
• Linting (task lint-fix) — clean.
• E2E tests (task test-e2e)
• Manual testing

API Compatibility

• This PR does not break the v1beta1 API.

No CRD changes. The only API surface delta is the package path of BuildHeaderForwardTripper. The helper was exported only by PR #5301; this PR moves that export to its final home before broader use.

Changes

File	Change
pkg/vmcp/headerforward/transport.go	New — moved from pkg/vmcp/client/header_forward.go, package renamed.
pkg/vmcp/headerforward/transport_test.go	New — moved from pkg/vmcp/client/header_forward_test.go.
pkg/vmcp/client/header_forward.go	Deleted.
pkg/vmcp/client/header_forward_test.go	Deleted.
pkg/vmcp/client/client.go	Updated import + call site to headerforward.BuildHeaderForwardTripper.

Does this introduce a user-facing change?

No.

Special notes for reviewers

• Branches off main, not off github_mcp_header (PR Wire HeaderForward into vMCP per-session HTTP client #5301). The two PRs are independent. Whichever merges first, the other's rebase is a one-line import-path update in mcp_session.go (PR Wire HeaderForward into vMCP per-session HTTP client #5301) or client.go (this PR).
• pkg/vmcp/headerforward/wirefmt/ is unchanged — it owns the env-var wire format used by the operator to pass header-forward config into the vmcp pod; the new transport.go is the runtime that consumes that config.
• No new logic, no new tests, no new error paths. If this PR's diff isn't entirely renames + import path changes, something is wrong.

Generated with Claude Code

[lorr1]

Automated review loop opened per user request.

Reviewed the mechanical move of header-forward helpers from pkg/vmcp/client/ to the new sibling package pkg/vmcp/headerforward/. No findings. The diff is a clean rename: package declarations updated, buildHeaderForwardTripper exported as BuildHeaderForwardTripper, single call site in pkg/vmcp/client/client.go updated with a 3-line wrap necessary to stay under the 130-char lll limit (141 chars unwrapped). Verified:

• File-for-file diff vs origin/main shows only package rename, function-name capitalization, and an added package doc comment — no behavior change.
• No leftover references to the old location/name (rg is clean).
• pkg/vmcp/client/header_forward_integration_test.go correctly stayed in pkg/vmcp/client/: its subject is the NewHTTPBackendClient factory wiring and it only references the exported vmcpclient.NewHTTPBackendClient, no moved unexported types.
• Test coverage parity: pkg/vmcp/headerforward/transport_test.go is byte-identical to the old header_forward_test.go after the package and function-name rewrites.
• New file has a proper // Package headerforward ... doc comment naming both consumer packages.
• Import grouping in client.go follows the standard 3-group convention.
• SPDX headers preserved on both moved files.
• pkg/vmcp/headerforward/wirefmt/ subpackage untouched.
• Local go build ./pkg/vmcp/... and go test ./pkg/vmcp/headerforward/... ./pkg/vmcp/client/... both pass.

Note on CI: the Tests / Test Go Code (ubuntu-8cores-32gb) check failed due to a runner shutdown (task: Signal received: "terminated", The runner has received a shutdown signal) — infrastructure flake, not a real test failure. Will retrigger and confirm green.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 68.46%. Comparing base (4893b65) to head (ae10f1e).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5302      +/-   ##
==========================================
- Coverage   68.46%   68.46%   -0.01%     
==========================================
  Files         620      620              
  Lines       63358    63360       +2     
==========================================
  Hits        43379    43379              
- Misses      16741    16746       +5     
+ Partials     3238     3235       -3     

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