feat(routing): CockroachDB support, payment-audit trace fix, and cost-aware routing

[jagan-jaya]

Bundles three independent changes made together this session. Each is its own commit, so they can be reviewed (or reverted) separately.

1. CockroachDB support (feat(db))

CockroachDB is PostgreSQL wire-compatible, so it runs on the existing postgres feature and migrations_pg unchanged.

• Optional pg_sslmode / pg_ssl_root_cert on PgDatabase, applied through a single shared connection-URL builder in storage.rs (secure / CockroachDB Cloud clusters).
• docker-compose.cockroach.yml overlay: swaps the postgresql service for a single-node CockroachDB on host 26257 (coexists with a local Postgres on 5432), creates the role/DB, and sets default_int_size=4 + serial_normalization='sql_sequence' so INTEGER/SERIAL typing matches schema_pg.rs.
• diesel_pg_cockroach.toml (no [print_schema]) so diesel migration run doesn't fail on CockroachDB's information_schema introspection.
• oneclick.sh --cockroach flow + README section.

Verified: all migrations_pg DDL applies on CockroachDB v24.1.5; column types come out Int4/Int8 correctly; end-to-end oneclick.sh --cockroach brings up the stack and serves live traffic.

2. Payment-audit trace fix (fix(analytics))

The audit timeline and the raw summary path reused the list-level dimension filters (status, gateway, routing_approach, …), which fragmented a single transaction's trace — e.g. status=failure dropped the decide_gateway events and left only the update_gateway_score failure event, and each match card under-counted events.

• Timeline uses a scope-only filter set, so a selected txn shows both decide_gateway and update_gateway_score.
• raw_summary_fragment / load_exact use scope+routing filters, so the per-card event count reflects the full trace (consistent with the materialized path).

Verified against live ClickHouse data + unit tests.

3. Cost-aware tie-break + EV-ranked candidates (feat(routing))

• Multi-objective now adopts its EV-best pick on AUTH_WON too (not only COST_WON), so tied SR scores resolve deterministically to the cheaper PSP instead of an arbitrary same-score tie-break. decided_gateway no longer disagrees with multi_objective_info.
• Replaced srHead/chosen with a ranked candidate list (auth, cost, EV per PSP, best-EV first) flagged isSrHead/isChosen — a decision now explains why the runner-up lost (its cost is visible even on AUTH_WON). UI panels + the simulator's authGap read the flagged rows; AUTH_WON collapses to one card instead of two duplicates.
• Config: dlocal seed-cost tiers (LATAM/APAC/MEA).

Breaking API change: multi_objective_info.srHead / .chosen are removed; consumers should read the flagged ranked rows. All in-repo consumers (backend A/B cost attribution, both UI panels, simulator authGap) are updated.

Verified: cargo build + cargo test (decider + analytics suites) pass; frontend tsc --noEmit clean.

[Copilot]

Pull request overview

This PR bundles three independent improvements across the backend and dashboard: (1) CockroachDB (PostgreSQL-wire) support in local/dev workflows, (2) a ClickHouse payment-audit filtering fix to prevent per-transaction trace fragmentation, and (3) cost-aware/deterministic multi-objective routing with a richer “ranked candidates” explanation surface for consumers.

Changes:

• Add CockroachDB local support via compose overlay + oneclick.sh flag, plus optional Postgres SSL query parameters in config/URL building.
• Fix payment-audit timeline vs summary filtering so a selected transaction returns its full curated trace rather than being truncated by list-level dimension filters.
• Replace srHead/chosen with an EV-ranked candidate list (ranked) and make AUTH-wins adopt the EV-best head deterministically to avoid “decided gateway” vs “info” mismatches.

Reviewed changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
website/src/types/api.ts	Introduces RankedPsp and updates MultiObjectiveInfo to use ranked instead of srHead/chosen.
website/src/components/pages/DecisionSimulatorPage.tsx	Updates simulator panels and derived metrics to read SR-head/chosen from flagged ranked rows and renders all ranked candidates.
website/src/components/pages/DecisionExplorerPage.tsx	Same UI update as simulator: renders ranked candidates and consumes flags instead of removed fields.
src/storage.rs	Centralizes Postgres URL construction and appends optional sslmode/sslrootcert (for secure Cockroach/Postgres clusters).
src/decider/gatewaydecider/multi_objective/mod.rs	Extends multi-objective API model with ranked: Vec<RankedPsp> and updates docs/serialization.
src/decider/gatewaydecider/multi_objective/algorithm.rs	Implements EV-ranked candidate list, deterministic AUTH-won decision adoption, and adds tests for tie determinism + ranked output.
src/decider/gatewaydecider/flow_new.rs	Ensures decided gateway follows multi-objective output when present (including AUTH_WON) and adjusts cost attribution extraction.
src/config.rs	Adds pg_sslmode and pg_ssl_root_cert to PgDatabase config.
src/analytics/clickhouse/metrics/audit_timeline.rs	Switches timeline queries to the new scope-only filter set to avoid fragmenting a selected transaction’s trace.
src/analytics/clickhouse/metrics/audit_summaries.rs	Adjusts raw/exact summary paths to use scope-appropriate filters so event counts reflect full traces.
src/analytics/clickhouse/filters.rs	Adds payment_audit_timeline_filters and payment_audit_summary_scope_filters plus unit tests.
README.md	Documents CockroachDB usage and the oneclick.sh --cockroach workflow.
oneclick.sh	Adds --cockroach/--postgres selection, Cockroach init flow, and Cockroach-specific Diesel migration invocation.
docker-compose.cockroach.yml	New compose overlay to replace Postgres with single-node CockroachDB and run init/migrations against it.
diesel_pg_cockroach.toml	New Diesel CLI config to avoid CockroachDB information_schema schema-regeneration failure.
config/development.toml	Adds seed-cost tiers (notably for dlocal) to support cost-aware routing experiments locally.

Suppressed comments (1)

src/decider/gatewaydecider/multi_objective/algorithm.rs:273

• build_ranked sorts only by ev. When two candidates have equal (or non-comparable) EV, the resulting order falls back to the underlying HashMap iteration order, which is intentionally non-deterministic. Since this list is presented as "ranked (best first)", add a deterministic tie-break (e.g. PSP name) to keep ordering stable.

    let mut ranked: Vec<RankedPsp> = score_map
        .iter()
        .filter(|(gw, _)| cost_bps(gw).is_finite())
        .map(|(gw, &score)| {
            let c = cost_bps(gw);
            RankedPsp {
                summary: make_summary(gw.clone(), score, Some(c), costs),
                ev: ev(score, c),
                is_sr_head: head_psp == Some(gw.as_str()),
                is_chosen: chosen_psp == Some(gw.as_str()),
            }
        })
        .collect();
    ranked.sort_by(|a, b| b.ev.partial_cmp(&a.ev).unwrap_or(std::cmp::Ordering::Equal));
    ranked

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