fix:(drand): SizeTrackingCache cache name per drand network name

[EclesioMeloJunior]

Summary of changes

Changes introduced in this pull request:

• While adding metrics to track the Drand HTTP relay usage noticed that the field verified_beacons is always initialized with SizeTrackingCache::new_with_metrics("verified_beacons", CACHE_SIZE), so any instance will create/export the metrics using that verified_beacons.
• The problem is that we call DrandBeacon::new for every point and for mainnet there are 3 points and for calibnet we have 2 points, and that expose the metrics 3 times with the same naming
• This PR solves that by appending the config.network_type to the cache name which avoids the metrics naming conflict

Reference issue to close (if applicable)

N/A

Other information and links

Change checklist

• I have performed a self-review of my own code,
• I have made corresponding changes to the documentation. All new code adheres to the team's documentation standards,
• I have added tests that prove my fix is effective or that my feature works (if possible),
• I have made sure the CHANGELOG is up-to-date. All user-facing changes should be reflected in this document.

Outside contributions

• This pull request is based on an issue that a maintainer has accepted (see Before Opening a Pull Request).
• I have read and agree to the CONTRIBUTING document.
• I have read and agree to the AI Policy document. I understand that failure to comply with the guidelines will lead to rejection of the pull request.

Summary by CodeRabbit

• Bug Fixes

  • Prevented duplicate drand cache metric families by enabling verified-entry caching only for Quicknet.
  • Disabled drand caching for Mainnet and Incentinet where it is not needed.
  • Restored consistent verified-beacon metric naming.

• Documentation

  • Updated the changelog to document network-specific drand cache behavior and metrics.

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• CHANGELOG.md
• src/beacon/drand.rs
• src/beacon/tests/drand.rs
• src/networks/drand.rs

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• CHANGELOG.md

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Walkthrough

Drand verified-entry caching is now optional. Mainnet and Incentinet disable it by default, while Quicknet retains it. Tests verify five unique cache metric families and reset the global registry after execution.

Changes

Drand cache configuration

Layer / File(s)	Summary
Optional cache behavior src/beacon/drand.rs	DrandConfig adds use_cache. DrandBeacon creates and accesses the verified-entry cache only when enabled.
Network cache defaults src/networks/drand.rs	Mainnet and Incentinet disable caching. Quicknet enables caching.
Cache metric validation src/beacon/tests/drand.rs, CHANGELOG.md	Tests validate five unique metric families from one caching beacon and clean up the global registry. The changelog records the network-specific cache behavior.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: 🔵 Low · up to 6ce12

Cache metric names now include the drand network name, which prevents naming collisions but may stop existing dashboards, alerts, or consumers that rely on the previous exact names from matching; migration guidance or owner awareness is needed before merge.

Suggested reviewers: akaladarshi, lesnyrumcajs

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 9 functions across 3 files. (1 skipped: 1 unsupported.)	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the Drand cache naming change, which is a primary part of the pull request.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Actionable comments posted: 2

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Inline comments:
In `@CHANGELOG.md`:
- Around line 38-39: Update the drand entry cache metrics changelog entry to
classify the rename as a breaking observability change under the existing
Breaking section, or add explicit migration guidance mapping
cache_verified_beacons_* to cache_verified_beacons_<network>_* for Prometheus
alerts, dashboards, and queries.

In `@src/beacon/tests/drand.rs`:
- Around line 311-343: Update verified_beacons_cache_metrics_are_uniquely_named
to restore the process-global collector registry after the test, using
panic-safe cleanup so the reset performed at the start does not leave its
registered collectors installed for later tests.

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📒 Files selected for processing (3)

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• src/beacon/tests/drand.rs

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• filecoin-project/lotus (manual)

Included review availability: 4 reviews are currently available. Your included PR review attempts over the past 7 days set your current allowance at 5 reviews per hour.

[LesnyRumcajs]

While it's technically correct, it's kind of not pragmatic. Incentinet and mainnet are a thing of the past and we should expect it to always show zero, with the exception of someone serving some really old archival data.

Prometheus metrics are scraped every X seconds, then persisted. We should keep only metrics useful to operators and ourselves.