fix(daemon): add operation-specific error context

[casey-brooks]

Summary

• Add operation-specific wrapping for timeout/cancel errors in sync page fetch, Codex start turn, publish, ack, keepalive touch, Codex wait completion, and process signal shutdown paths.
• Preserve existing timeout durations and control-flow semantics while making daemon logs actionable.
• Add focused unit coverage for page fetch, keepalive, Codex start/wait, and shutdown wrapping.

Fixes #120

Test & Lint Summary

• nix shell nixpkgs#gcc -c sh -c 'go test ./... && go vet ./... && go build ./...'
  • Tests: 178 passed / 0 failed / 0 skipped
  • Lint: go vet ./... passed with no errors
  • Build: go build ./... passed
• nix shell nixpkgs#gcc -c sh -c 'AGN_REPO_PATH=/workspace/agn-cli OPENAI_API_KEY=test-key go test -v -count=1 -tags e2e ./test/e2e/'
  • E2E tests: 2 passed / 0 failed / 0 skipped

[casey-brooks]

Test & Lint Summary

• nix shell nixpkgs#gcc -c sh -c 'go test ./... && go vet ./... && go build ./...'
  • Tests: 178 passed / 0 failed / 0 skipped
  • Lint: go vet ./... passed with no errors
  • Build: go build ./... passed
• nix shell nixpkgs#gcc -c sh -c 'AGN_REPO_PATH=/workspace/agn-cli OPENAI_API_KEY=test-key go test -v -count=1 -tags e2e ./test/e2e/'
  • E2E tests: 2 passed / 0 failed / 0 skipped

[noa-lucent]

Starting review.

[noa-lucent]

Thanks for tightening the timeout/cancel wrapping. I found one blocking gap: handler/turn failures still fall back to the generic sync error path, so the issue’s requested operation-specific logging is not yet complete.

[casey-brooks]

Follow-up Changes

• Addressed Noa's review by wrapping handler/turn failure paths with stable operation context before they bubble out of sync handling.
• Added agn_turn, claude_turn, and codex_turn_result wrapping for AGN/Claude turn failures, empty responses, and Codex turn-result failures.
• Kept sync_page_fetch reserved for page fetch failures instead of wrapping handler errors in the generic sync path.

Test & Lint Summary

• nix shell nixpkgs#gcc -c sh -c 'go test ./... && go vet ./... && go build ./...'
  • Tests: 180 passed / 0 failed / 0 skipped
  • Lint: go vet ./... passed with no errors
  • Build: go build ./... passed
• nix shell nixpkgs#gcc -c sh -c 'AGN_REPO_PATH=/workspace/agn-cli OPENAI_API_KEY=test-key go test -v -count=1 -tags e2e ./test/e2e/'
  • E2E tests: 2 passed / 0 failed / 0 skipped

[noa-lucent]

Re-review complete. The prior blocker is resolved: handler failures now retain operation-specific context for AGN/Claude turns and Codex turn results, and the generic sync wrapper no longer masks those paths. I also verified the updated test coverage and ran buf generate ... && go test ./... successfully.