feat(telemetry): observe cluster remote fallback persistence

[krisztian-gajdar]

A model can keep bridging remotely while local capacity stays unavailable. Declare and emit bounded gateway fallback counters and a remote-serving duration gauge, expose them in the queue-routing dashboard, and alert only when recent committed bridges from the same producer/collector generation exceed the configured persistence threshold.

The request owns one observation through buffered validation or the first valid remote stream event. Local streams reset persistence only after valid output is accepted; HTTP 200 before an error does not reset it. Idle gaps over five minutes start a new period. The facade retains at most 256 exact model names for its lifetime; overflow affects only the counter. Collector allowlists retain only declared attributes, and the pinned-container regression covers duplicate/non-scalar labels and gateway-only metrics sent to the application receiver.

Validation:

• Full gateway suites: 1613 default and 1624 cloud-storage tests in both library and binary targets, plus 3 affinity, 2 NAK and 4 ACL integrations per configuration (8 existing ignored tests).
• Post-rebase fallback, local-stream transfer and live-driver regressions on both configurations; both Clippy configurations and rustfmt.
• 48 Helm/dashboard/cardinality checks; changed collector test passes Ruff and its protobuf payload/render smoke check. The existing Helm test file retains exactly its 21 baseline lint findings with none added.
• Pinned Docker collector privacy execution runs in CI; it was not claimed as a local container result.
• Independent adversarial source review cleared request ownership, first-output boundaries, idle resets, label/state bounds, collector privacy and alert freshness.

Security sibling sweep: 17 recording/transfer instances in 4 files, 5 observation/first-output ownership instances in 2 files, and 25 bound/state instances in 2 files. All local constructors transfer only gateway-owned canonical catalog names, and explicit remote routes/active bridges cannot clear local persistence. No inputs, response bodies, upstream URLs or credentials enter the new labels.

Part of #415. Coordinated threshold routing, numerical fleet admission and measured acceptance evidence remain separate deliveries.

Summary by CodeRabbit

• New Features
  • Added dashboard panels for remote fallback responses and time spent serving remotely since the last local success.
  • Added fallback metrics that break down responses by model, operation, reason, and outcome, and track remote-serving duration.
  • Added an alert for persistent remote serving, configurable from 1 second to 24 hours and defaulting to 10 minutes. It requires recent committed fallback activity.
• Documentation
  • Added guidance on interpreting fallback metrics, dashboard breakdowns, alert conditions, and how successful local serving resets the observed duration.

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• packages/sie_gateway/src/observability/metrics.rs

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• packages/sie_gateway/src/observability/metrics.rs

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📝 Walkthrough

Walkthrough

The gateway now records remote fallback outcomes and per-model serving duration. Helm collector configuration exports these metrics. The dashboard and configurable Prometheus alert display fallback activity and persistence.

Changes

Gateway remote fallback observations

Layer / File(s)	Summary
Metric contract and recording telemetry/contract.yaml, packages/sie_gateway/src/types/model.rs, packages/sie_gateway/src/observability/*	Defines bounded fallback counter and serving-duration metrics. The gateway tracks committed and refused fallbacks, idle resets, and local-success resets. Tests cover recording rules and metric bounds.
Serving lifecycle instrumentation packages/sie_gateway/src/handlers/proxy.rs, packages/sie_gateway/src/handlers/serving_disclosure.rs, packages/sie_gateway/src/handlers/sse.rs	Passes model and operation observations into fallback tracking. Records fallback outcomes at response completion and local success after valid SSE output. Tests cover stream observations and worker-error timing.
Export and cluster observability deploy/helm/sie-cluster/templates/*, deploy/helm/sie-cluster/values.yaml, deploy/helm/sie-cluster/files/alerts/sie-rules.yaml, deploy/helm/sie-cluster/files/dashboards/queue-routing.json, tools/ci/tests/test_*, packages/sie_server/REMOTE_BACKENDS.md, telemetry/README.md	Allows the metrics through collector filters and defines their units and attributes. Adds a validated alert threshold, persistence alert, dashboard panels, render and privacy tests, and metric documentation.

Sequence Diagram(s)

sequenceDiagram
  participant ProxyHandlers
  participant FallbackAttempt
  participant SseDriver
  participant MetricsFacade
  participant OTelCollector
  participant PrometheusGrafana
  ProxyHandlers->>FallbackAttempt: Record model and operation
  FallbackAttempt->>MetricsFacade: Record fallback outcome
  SseDriver->>MetricsFacade: Record local success after valid output
  MetricsFacade->>OTelCollector: Export fallback counter and duration gauge
  OTelCollector->>PrometheusGrafana: Forward allowed gateway metrics

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Suggested reviewers: svonava

Priority: ➖ Normal

Merge Risk: ⚪ Minimal · up to 11d38

No actionable merge-blocking risk is established for the clock-ordering change; merge after normal checks.

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❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 46.15% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 39 functions across 7 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

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Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main change: adding telemetry to observe persistent cluster remote fallback.

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[krisztian-gajdar]

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Inline comments:
Review comments at @packages/sie_gateway/src/observability/metrics.rs:
- Line 1630: Move the Instant::now() capture in the bridge-time update path to
after the state lock is acquired, so timestamps follow the same order as state
updates and period.latest cannot move backward. Keep the existing duration and
period calculations unchanged.

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📥 Commits

Reviewing files that changed from the base of the PR and between 4f3a62e and b44c877.

📒 Files selected for processing (16)

• deploy/helm/sie-cluster/files/alerts/sie-rules.yaml
• deploy/helm/sie-cluster/files/dashboards/queue-routing.json
• deploy/helm/sie-cluster/templates/_otel-collector-config.tpl
• deploy/helm/sie-cluster/templates/prometheusrule.yaml
• deploy/helm/sie-cluster/values.yaml
• packages/sie_gateway/src/handlers/proxy.rs
• packages/sie_gateway/src/handlers/serving_disclosure.rs
• packages/sie_gateway/src/handlers/sse.rs
• packages/sie_gateway/src/observability/metrics.rs
• packages/sie_gateway/src/observability/tracing.rs
• packages/sie_gateway/src/types/model.rs
• packages/sie_server/REMOTE_BACKENDS.md
• telemetry/README.md
• telemetry/contract.yaml
• tools/ci/tests/test_collector_metric_privacy.py
• tools/ci/tests/test_helm_render.py

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[krisztian-gajdar]

Moved the production Instant read inside the fallback-state lock, preserving serialization order for the period timestamps. The injectable test clock is evaluated at the same point. Focused fallback metric tests pass on both gateway configurations; both Clippy configurations and rustfmt pass. @coderabbitai review

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@krisztian-gajdar Thanks for the update. I’ll request a review of the latest commit, including the clock evaluation inside the fallback-state lock.

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