fix(site-explorer): widen duration histogram buckets

[Susanpdl]

Summary

Site explorer iteration latency uses the default OpenTelemetry histogram buckets, which top out at 10 seconds. On production sites most observations land in the +Inf bucket, so the metric is not useful for monitoring.

This change registers explicit millisecond buckets up to one hour for site explorer duration histograms, including iteration latency and per endpoint exploration duration.

Fixes #2352

Test plan

• Added unit test that histogram views build successfully
• CI cargo test -p carbide-site-explorer
• After deploy, confirm carbide_site_explorer_iteration_latency_milliseconds_bucket observations spread across buckets above 10s instead of concentrating in +Inf

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[coderabbitai]

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📥 Commits

Reviewing files that changed from the base of the PR and between c623bed and b6ee2bc.

📒 Files selected for processing (2)

• crates/api-core/src/logging/setup.rs
• crates/site-explorer/src/metrics.rs

🚧 Files skipped from review as they are similar to previous changes (2)

• crates/api-core/src/logging/setup.rs
• crates/site-explorer/src/metrics.rs

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Summary by CodeRabbit

• New Features
  • Expanded site-explorer observability with additional OpenTelemetry latency histograms, including explicit millisecond bucket boundaries and min/max recording.
  • Exposed a reusable helper to create latency histogram views, and re-exported the site-explorer latency histogram view at the crate level.
• Tests
  • Added unit tests covering histogram view creation for specific and wildcard name filters.
  • Updated gauge aggregation test setup to include the new site-explorer histogram views.

Walkthrough

This PR resolves a histogram bucket misconfiguration for site-explorer latency metrics by introducing explicit millisecond bucket boundaries. It adds site_explorer_latency_histogram_view, a new public function defining those boundaries, integrates required dependencies, re-exports the function from the crate root, and registers the resulting views in the OTel MeterProvider for both production and test contexts.

Changes

Site Explorer Histogram Bucket Fix

Layer / File(s)	Summary
Histogram view function and dependencies crates/site-explorer/Cargo.toml, crates/site-explorer/src/metrics.rs	Adds carbide-metrics-utils and opentelemetry_sdk dependencies. Updates imports to include Aggregation and InstrumentKind from opentelemetry_sdk::metrics. Defines explicit millisecond bucket boundaries and implements site_explorer_latency_histogram_view with Aggregation::ExplicitBucketHistogram and record_min_max: true. Includes unit tests verifying view construction for wildcard and specific name filters.
Public re-export and MeterProvider registration crates/site-explorer/src/lib.rs, crates/api-core/src/logging/setup.rs	Re-exports site_explorer_latency_histogram_view at the site-explorer crate root. Registers both the wildcard *site_explorer*latency* and carbide_endpoint_exploration_duration histogram views in the production create_metrics MeterProviderBuilder and mirrors the configuration in the test test_gauge_aggregation builder.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: widening duration histogram buckets for site-explorer to address the issue of observations concentrating in the +Inf bucket.
Description check	✅ Passed	The description is comprehensive and directly related to the changeset, explaining the problem, solution, and test plan for the histogram bucket expansion.
Linked Issues check	✅ Passed	The changes directly address issue #2352 by implementing explicit millisecond histogram buckets for site-explorer duration metrics, replacing inadequate default buckets with a custom configuration extending to one hour.
Out of Scope Changes check	✅ Passed	All modifications are directly scoped to implementing explicit histogram buckets for site-explorer metrics; no extraneous changes are present outside the stated objectives.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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[Copilot]

Pull request overview

This PR improves observability for carbide-site-explorer by configuring explicit OpenTelemetry histogram buckets (in milliseconds) that extend up to 1 hour, so long-running site explorer operations no longer concentrate in the +Inf bucket and become unusable for monitoring.

Changes:

• Add a reusable site_explorer_latency_histogram_view() helper that builds an explicit-bucket histogram view for site explorer duration metrics.
• Export the helper from carbide-site-explorer and register the views in carbide-api-core’s metrics setup.
• Add dependencies (carbide-metrics-utils, opentelemetry_sdk) and a unit test to ensure the view builder succeeds.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
crates/site-explorer/src/metrics.rs	Adds explicit histogram bucket boundaries + a helper for constructing OTel views; adds a basic build test.
crates/site-explorer/src/lib.rs	Re-exports the view helper for use by other crates.
crates/site-explorer/Cargo.toml	Adds dependencies needed to build OTel metric views.
crates/api-core/src/logging/setup.rs	Registers the new site-explorer histogram views during meter provider construction (and mirrors it in tests).

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[coderabbitai]

🧹 Nitpick comments (1)

crates/site-explorer/src/metrics.rs (1)

769-777: ⚡ Quick win

Prefer table-driven cases for the view-construction test.

This test calls the same fallible operation with multiple input variants; converting it to a scenario table will make extension and failure labeling cleaner.

As per coding guidelines, “Reach for a table whenever two or more tests call the same operation with different inputs.”

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@crates/site-explorer/src/metrics.rs` around lines 769 - 777, The test
function site_explorer_latency_histogram_views_build calls the same operation
site_explorer_latency_histogram_view multiple times with different inputs.
Refactor this into a table-driven test by creating a collection of test case
tuples containing the input string and a descriptive label for each variant,
then iterate over this collection to call the function once per case. This will
make the test more maintainable and easier to extend with additional cases in
the future.

Source: Coding guidelines

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@crates/site-explorer/src/metrics.rs`:
- Around line 769-777: The test function
site_explorer_latency_histogram_views_build calls the same operation
site_explorer_latency_histogram_view multiple times with different inputs.
Refactor this into a table-driven test by creating a collection of test case
tuples containing the input string and a descriptive label for each variant,
then iterate over this collection to call the function once per case. This will
make the test more maintainable and easier to extend with additional cases in
the future.

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ℹ️ Review info

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Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

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📥 Commits

Reviewing files that changed from the base of the PR and between d5e5b61 and c623bed.

📒 Files selected for processing (4)

• crates/api-core/src/logging/setup.rs
• crates/site-explorer/Cargo.toml
• crates/site-explorer/src/lib.rs
• crates/site-explorer/src/metrics.rs