[cppla]

Summary

• Treat entirely already-closed listener errors as benign, including net/http's duplicate close during HTTP shutdown.
• Preserve mixed/unknown/context error trees and original error identities.
• Do not skip tracked-connection cleanup after a genuine listener-close failure. Continue caller-bounded graceful/forced cleanup and report both close and deadline failures.
• Add deterministic real-TCP shutdown regressions, 41 error-tree controls and canceled/deadline identity controls. Document source-build behavior; no v1.0.1 artifact or release change.

Validation of d71d30a

• Same selected final API regressions fail as expected against preserved prior production; final candidate race x3 passes all 27 actual API cases. The old-production overlay excludes only the new, unselected helper-only test file to permit compilation; selected API assertions are unchanged.
• Full make check and make race passed on the final frozen files. Includes vet, shuffled Go tests, dependency/module/notices checks and 49 release-script tests.
• Additional classifier/HTTP race controls and healthy CONNECT upload-half-close control passed.
• Actual Linux arm64 binary (Go 1.25.13) passed 15 new top-level executions and 22 existing controls in two isolated existing-image containers. No networking, capabilities, image pull or Docker configuration change; source/module/doc inventories remained unchanged, containers removed.
• Independent implementation/fixture reviews found no blocker.

An initial fixture vet failure was corrected with explicit cancellation before final full gates. An initial offline Go-launcher setup error occurred before Linux compilation/tests; final verification used the hashed cached compiler directly. Prior logs are retained rather than counted as final successes.

Scope

No protocol/authentication/admission/relay/half-close/default-budget change. Injected unrelated listener failures are regression controls, not an OS incidence estimate. No browser-equivalence, large corpus, remote-host, deployment or new release claim. Caller context remains the cleanup bound; a noncooperative custom Listener.Close is not forcibly interruptible.

GitHub verification completed on the exact head: CI run 37039232746 (all 11 jobs), CodeQL 37039232784, Linux netem 37039232676, all successful on attempt 1. Container integration and completed dual-platform OCI export, plus netem success, were confirmed in the actual job logs. Automated review reported no findings (COMMENTED, not a human approval); no review threads remained.

Post-merge verification

Merged as 1b1ebaaeaa1a81ad0c21af3614fd28ca1c37fe59. The full tree matches tested head d71d30a4b05ea1865baf9b8aa4a1d77341a891d4 (c71b2c01ee45a532361b95ad46b041f0bdb528b5), and local/remote main and five frozen file hashes agree. Main-focused race x3 passed (15 top-level executions). Main push runs also succeeded on attempt 1: CI 37039655691 (all 11 jobs), CodeQL 37039655679, Linux netem 37039655828. Actual main container/OCI and netem job logs confirmed successful integration and completed export. Worktree clean; no tag/release/deployment.

[Copilot]

Copilot review overview

🟢 Approval recommended

The implementation consistently preserves genuine errors, handles benign duplicate closes, and includes comprehensive regression coverage.

Review effort: Balanced
Findings: None

What changed in this PR

Improves shutdown error handling while ensuring tracked connections are cleaned up.

Changes:

• Classifies only wholly closed-listener error trees as benign.
• Preserves listener and context errors while completing cleanup.
• Adds deterministic shutdown regressions and deployment documentation.

File	Description
internal/​proxy/​lifecycle.go	Preserves shutdown errors and completes tracked cleanup.
internal/​proxy/​http.go	Normalizes duplicate HTTP listener-close errors.
internal/​proxy/​listener_close_error_test.go	Tests error-tree classification and context identity.
internal/​proxy/​http_shutdown_close_result_test.go	Tests real-TCP shutdown and close-error preservation.
docs/​DEPLOYMENT.md	Documents source-build shutdown behavior.

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