Make sharded tests hermetic from CI checkout state

[chubes4]

Summary

• isolate HOME, XDG, temp, runtime, artifact, and controller-fixture state under the shared test guard with panic-safe restoration
• prevent generated CI control-plane outputs from dirtying candidate checkouts and blocking committed-change harvest
• use a deterministic controller identity responder for in-process tests and narrow runner-handoff integration coverage to service-free contracts
• make extension result-parser fixtures POSIX-shell compatible and refresh stale generated CLI references
• include the one-line AdoptArgs fixture compile repair from Main test compile fails after AdoptArgs inherited-failure field addition #11995 so this branch can execute the shard suite

Verification

• cargo fmt --all -- --check
• cargo test --locked -p homeboy-core home_guard_owns_and_restores_xdg_and_temp_roots --lib
• cargo test --locked -p homeboy-core home_guard_test_scope_restores_the_real_environment_after_unwind --lib
• cargo test --locked -p homeboy-core current_test_controller_fixture_answers_with_the_cli_identity --lib
• cargo test --locked -p homeboy-agents --test agent_task_handoff_reconnect controller_proxy_remains_resolvable_after_detached_runner_acceptance
• cargo test --locked -p homeboy-agents --lib reconcile_terminalizes_an_unaccepted_controller_handoff_after_its_deadline
• cargo test --locked -p homeboy-cli nested_runner_artifact_handoff_supplies_declared_parser
• cargo test --locked -p homeboy-cli full_extension_test_supplies_canonical_result_sidecar
• cargo test --locked -p homeboy-cli generated_command_docs_match_the_live_clap_tree
• cargo test --locked -p homeboy-cli controller_run_from_spec_fork_isolates_repeated_replays_from_stale_child_runs

Addresses #11962 and supersedes the compile-only scope of #11996. Full shard CI will determine the remaining independent failure groups before this issue is closed.

AI Assistance

OpenAI gpt-5.6-sol via OpenCode diagnosed the CI failure corpus, implemented the test-support and fixture repairs, and iteratively reviewed and verified the patch under human direction. Chris Huber remains responsible for every line.

[homeboy-ci]

Homeboy Results — homeboy

Lint

✅ review lint — passed

ℹ️ Full options: homeboy self docs commands/lint
ℹ️ Save lint baseline: homeboy review lint homeboy --baseline
Deep dive: homeboy review lint homeboy --changed-since 66a6691

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-homeboy-review-lint-homeboy-fast-Linux contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-homeboy-review-lint-homeboy-fast-Linux contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/homeboy/actions/runs/31284375751

Audit

⚠️ review audit — no measurement

Deep dive: homeboy review audit homeboy --changed-since 66a6691

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-homeboy-review-audit-homeboy-fast-Linux contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-homeboy-review-audit-homeboy-fast-Linux contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/homeboy/actions/runs/31284375751

Tooling versions

• Homeboy CLI: homeboy 0.334.0+195fccd37499
• Extension: rust from https://github.com/Extra-Chill/homeboy-extensions
• Extension revision: a32e4ea3
• Action: unknown@unknown

[chubes4]

Superseded by #12012, which landed the corrected process-local shard isolation contract on main. AI assistance disclosure: OpenAI gpt-5.6-sol via OpenCode was used to verify patch equivalence and reconcile the PR queue.