[architect] refactor: remove unconsumed SLA config from tests/shared/timing.py (DEFAULT_SLA, SLA_STRICT) + pin the timings.jsonl reader contract

[kubestellar-hive]

Refactor

Cluster: the scenario-timing subsystem — tests/shared/timing.py, tests/unit/test_timing.py, new tests/unit/test_timing_contract.py, and the Summarise results step of .github/actions/gnome-e2e/action.yml (read-only; not modified).

Refs #764 — this lands the structural half of that issue only. It does not decide whether the factory wants SLA gating, which is the product question #764 raised, so the issue stays open.

1. Remove two constants nothing reads

tests/shared/timing.py defined DEFAULT_SLA and SLA_STRICT; neither had a reader anywhere in the repo.

• _scenario_sla_seconds resolves a threshold purely from an @sla_<n>s scenario tag and returns None otherwise, so no scenario could ever pick up a DEFAULT_SLA entry.
• record_end never branched on SLA_STRICT. Setting TIMING_SLA_STRICT=1 in a workflow to "turn on" SLA gating was a silent no-op, and the resulting green run read as evidence the suite met its SLAs.

Both are removed, along with the two tests that certified them — test_sla_strict_env_parsing asserted only that the env var parsed, and test_default_sla_thresholds_are_defined_for_future_use asserted only that the literal still equalled itself. Both passed regardless of whether anything acted on either value, so they reported the subsystem as covered while the enforcement it advertised was absent.

No behaviour change. Nothing consumed either name, so nothing can observe their removal.

2. timings.jsonl is no longer orphaned — so pin the contract instead

#764 reported the file had no consumer. That has since changed and the issue is stale on this point: .github/actions/gnome-e2e/action.yml (Summarise results) reads results/timings.jsonl and reports every entry whose sla_violated is true and whose status is not skipped.

That makes the key names in record_end a real contract — but one that spans a Python module in tests/shared and a python3 - <<'PYEOF' heredoc inside a composite action. Nothing connected the two, so renaming a key would stop SLA reporting silently with every suite still green.

New tests/unit/test_timing_contract.py:

• test_summariser_reads_only_keys_record_end_writes — parses the action YAML, extracts every entry.get("...") in the summariser, and asserts each key is actually written by record_end.
• test_sla_violation_is_reported_for_a_tagged_overrun / test_untagged_scenario_has_no_sla_and_never_violates — cover the flag the summariser filters on, in both directions.
• test_module_constants_are_consumed_by_the_module — AST-walks timing.py and fails on any public module-level constant that the module never loads. This is the general form of the bug being fixed, so a third unconsumed knob cannot come back.

The module docstring now states the contract and records that a violation is reported, never enforced, so the code stops implying a strict mode it does not have.

Verification

Both new guards were confirmed to fail when the defect is reintroduced, not merely to pass today:

• re-adding DEFAULT_SLA/SLA_STRICT → AssertionError: tests/shared/timing.py defines ['DEFAULT_SLA', 'SLA_STRICT'] but never reads them.
• renaming sla_violated → sla_breached → AssertionError: ... reads ['sla_violated'] from timings.jsonl, but tests/shared/timing.py:record_end does not write those keys. SLA reporting would silently stop.

Full unit suite on this branch: 1524 passed.

Scope check

No open PR touches tests/shared/timing.py, tests/unit/test_timing.py, or .github/actions/gnome-e2e/action.yml. This is disjoint from #791 / #779 (results-directory contract): that cluster is resolve_results_dir and where artifacts are written; this one is what one artifact contains and who reads it. timing.py consumes resolve_results_dir and this PR leaves that call untouched.

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Filed by architect agent (ACMM L5 — hold-gated mode). Hold-gated: human review required — do not merge without review.

— hive: agent=architect backend=copilot model=claude-opus-5

[codecov-commenter]

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Codecov Report

❌ Patch coverage is 97.82609% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
tests/unit/test_timing_contract.py	97.82%	1 Missing ⚠️

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