[rafa-stacks]

Adds a mempool_tx_confirmation_seconds Prometheus histogram that measures how long each tx waits between first being received into the mempool and being mined, labeled by tx type so it can be split per type in Grafana.

mempool_tx_confirmation_seconds{type="token_transfer|contract_call|smart_contract|..."}

• Value: block_time - receipt_time in seconds, clamped to ≥ 0 to absorb clock differences between the miner and the mempool observer.
• Type label: uses getTxTypeString, the same values as the existing mempool_tx_count{type}.
• Buckets: 1, 2, 3, 4, 5, 7, 10, 15, 20, 30, 45, 60, 120, 300, 600, 1800, 3600, 7200, 21600. Dense below a minute, where most Nakamoto confirmations land.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[Copilot]

🟡 Changes recommended

Confirmation observations can omit known transactions or use unreliable receipt timestamps.

3 open findings

• Preserve first mempool receipt time across re-admission and restore · New
• Include previously pruned transactions in mined confirmation results · New
• Reject out-of-range finite receipt timestamps before database insertion · New

What changed in this PR

Adds a transaction-type confirmation-time histogram to existing mempool monitoring, using SNP receipt timestamps to improve catch-up accuracy.

Changes:

• Preserves SNP timestamps during event ingestion.
• Emits mined-transaction metadata after commit and records confirmation durations.
• Adds timestamp, filtering, lag-cutoff, and replay tests.

File	Description
tests/​snp/​snp-ingestion.test.ts	Checks original receipt times after replay.
tests/​api/​mempool/​mempool-confirmation-metric.test.ts	Tests timing helpers and ingestion behavior.
src/​event-stream/​snp-event-stream.ts	Forwards SNP timestamps.
src/​event-stream/​event-server.ts	Resolves and passes receipt times.
src/​env.ts	Configures the observation lag cutoff.
src/​datastore/​pg-write-store.ts	Collects and emits mined-transaction metadata.
src/​datastore/​pg-store-event-emitter.ts	Defines the confirmation event.
src/​datastore/​helpers.ts	Calculates durations and registers the histogram.
src/​datastore/​common.ts	Defines confirmation metadata.

🧠 Review effort: Balanced

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