Retain bounded diagnostics for intermittent network summary failures #569

Worker brief

Related unresolved failure: #563. The operator authorized this diagnostics prerequisite on maintenance & gates, reusing existing draft PR #568. No second implementation or PR is needed.

The nightly summary metadata/key assertion failed once; the retained failure lacks enough observations to identify a cause. Both the isolated network phase and the nightly prefix subsequently passed without a product fix. This prerequisite supplies bounded instrumentation for a future recurrence; it does not resolve #563.

Acceptance criteria:

• Emit fixed boolean summary diagnostics without response bodies, key names, timestamps, secrets or parser errors.
• Preserve the strict summary assertion and failure row in tests/e2e-pithead.sh, plus the existing lock, snapshot and restoration lifecycle.
• Provide a narrow network-sequence phase reproducing connect → worker-api → api-impact → network in one process/snapshot, stopping on fatal errors or failed rows and omitting later phases.
• Require regressions for diagnostic sanitization, phase wiring, sequence order/shared state and failure propagation, with corrected test documentation.
• Require green GitHub checks and current-head rigforge tier4-e2e proof. Completed job 2054@48b227098a8eae72503de741de18d12d740fe6b3 supplies that instrumentation proof; obtain fresh evidence if the head changes.
• Submit the prerequisite to the separate adversarial-review gate. Author-side verifier/security reviews do not replace that gate.

Implementation and focused tests are complete in PR #568 at 48b227098a8eae72503de741de18d12d740fe6b3; all eight GitHub checks passed. Full logs/status/artifacts of the completed reproductions were audited and their generated evidence is in the PR body.

Only this prerequisite may close when the diagnostic PR lands. #563 stays open on v2 - appliance; after landing, its next evidence source is the scheduled rigforge nightly. Diagnose any recurrence from the full artifacts. Do not run a speculative rerun loop or describe the passing reproductions as a root-cause fix.