starknet_transaction_prover: bump prover_panics_total on panic hook fire

[avi-starkware]

Bumps the new prover_panics_total counter from the panic hook before
constructing the backtrace, so dashboards can alert on panic rate without
log search. The pre-registered zero observation in install_exporter
keeps the series visible at scrape time even before the first panic.

Co-Authored-By: Claude Opus 4.7 (1M context) noreply@anthropic.com

[cursor]

PR Summary

Low Risk
Observability-only change to the panic hook and metrics registration; no change to proving, RPC, or request handling behavior.

Overview
Adds a prover_panics_total Prometheus counter so panic rate can be monitored and alerted on without log search.

The global panic hook now increments that counter first (before backtrace capture and structured tracing output), so a secondary panic during hook work still records the original event. install_exporter pre-registers the series at zero so /metrics exposes it before the first panic. A unit test asserts the hook bumps the counter by one when installed with a shared test recorder.

^{Reviewed by Cursor Bugbot for commit ac98d86. Bugbot is set up for automated code reviews on this repo. Configure here.}

[avi-starkware]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• starknet_transaction_prover: origin-level breadcrumbs for validation errors #14172
• starknet_transaction_prover: /health returns 503 when service is saturated #14171
• starknet_transaction_prover: bump prover_panics_total on panic hook fire #14170 👈 (View in Graphite)
• starknet_transaction_prover: HTTP request count + latency + in-flight metrics #14169
• starknet_transaction_prover: proving-job duration + outcome metrics #14168
• starknet_transaction_prover: Prometheus /metrics endpoint with build_info #14167
• starknet_transaction_prover: global panic hook + graceful SIGTERM shutdown #14166
• starknet_transaction_prover: per-request structured log with request-id #14165
• starknet_transaction_prover: redact URL credentials in logs and add startup banner #14164
• starknet_transaction_prover: add /health endpoint via HealthLayer #14163
• starknet_transaction_prover: add --log-format text|json CLI flag #14162
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[reviewable-StarkWare]

This change is 

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, have a team admin enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit ac98d86. Configure here.}

[cursor]

Two tests race on the global panic hook

Medium Severity

The previous code deliberately kept all panic-hook tests in a single #[test] to avoid racing on the process-global panic hook (the old comment explicitly said "must run serially"). Splitting into two separate #[test] functions introduces a race: Rust runs tests in parallel by default, and the take_hook/set_hook save-restore pattern is not atomic. If both tests interleave, one test can steal the other's installed hook, causing extracts_static_str_and_formatted_payloads to fire the real panic_hook instead of its capture closure, or panic_hook_bumps_panics_total_counter to fire a stale hook that doesn't increment the counter. Either test can then fail non-deterministically.

Additional Locations (1)

• crates/starknet_transaction_prover/src/server/panic_test.rs#L19-L26

 

^{Reviewed by Cursor Bugbot for commit ac98d86. Configure here.}