# Phase 8 Execution Checklist (Resilience, Scale, and Production Readiness)

Reference artifacts:
- `docs/wallet-implementation-plan-apps-mode.md`
- `docs/phase-tracker.md`
- `docs/adr/0010-release-strategy-and-migration-rollback.md`
- `docs/adr/0013-environment-and-infrastructure-topology.md`
- `docs/adr/0014-business-continuity-and-disaster-recovery.md`
- `docs/adr/0007-observability-and-audit-traceability-standard.md`
- `docs/adr/0009-data-partitioning-and-retention-policy.md`
- `docs/adr/0012-testing-strategy-and-quality-gates.md`

## 1. Phase Objective
Harden the wallet platform for active-active deployment and incident operations.

Deliver:
- Resilience domain: health checks, back-pressure controls, SLO tracking, incident command.
- Production domain: secrets/HSM integration, SIEM forwarding, DR rehearsal, readiness gate.
- Compliance waiver governance (deferred from Phase 7): exception submission, approval, expiry.
- Production readiness report and cutover/rollback plan.

Phase status:
- Start: `not-started`
- End: `done` — 2026-03-15
- SLO tracking, incident command, DR rehearsal domain, SIEM forwarder, secrets/HSM adapters,
  and compliance waiver governance operational; go-live readiness gate validation complete.

## 2. Scope
In scope:
- `wallet_resilience` and `wallet_production` app foundations.
- Health check, back-pressure policy, SLO violation, incident record lifecycle.
- Secrets/HSM provider behaviour + Azure Vault and Thales HSM adapter stubs.
- SIEM event format and configurable forwarder.
- DR checkpoint structure, DR rehearsal command, post-rehearsal evidence.
- Production readiness gate: checklists + sign-off approval record.
- Compliance exception/waiver governance workflow (deferred from Phase 7).

Out of scope:
- Full live cluster wiring (multi-node Mnesia / libcluster topology — infrastructure controlled).
- Production-level ML fraud model scoring pipeline (Phase 9+).
- Full Grafana/LiveView dashboard implementation (scaffolded via telemetry; UI tooling deferred).
- External SIEM platform connectors beyond forwarder interface and stub adapter.

## 3. Work Breakdown

## Track A: App Foundations
1. Create `wallet_resilience` OTP app with public interfaces.
- Owner: SRE Team
- Output: app scaffold, supervision tree, README.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_resilience/mix.exs` — umbrella app config; deps: shared_kernel + observability + events + jason + phoenix_pubsub.
  - `apps/wallet_resilience/lib/wallet_resilience/application.ex` — supervision tree starts SloViolationStore, IncidentStore.
  - `apps/wallet_resilience/README.md` — public interface, SLO bands, incident severity levels, back-pressure policy contract.

2. Create `wallet_production` OTP app with public interfaces.
- Owner: Platform + SRE Team
- Output: app scaffold, supervision tree, README.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_production/mix.exs` — umbrella app config.
  - `apps/wallet_production/lib/wallet_production/application.ex` — supervision tree starts DrCheckpointStore, ReadinessApprovalStore.
  - `apps/wallet_production/README.md` — public interface contract, readiness gate criteria, DR tier objectives, SIEM field schema.

## Track B: Resilience — Health Checks and Back-Pressure
1. Implement health check model.
- Owner: SRE Team
- Output: liveness/readiness check result with dependency states.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_resilience/lib/wallet_resilience/health_check.ex`
  - `HealthCheck.liveness/0` — returns `%{status: :ok | :degraded | :down, checks: [map()]}`.
  - `HealthCheck.readiness/1` — evaluates dependency list; returns per-dependency pass/fail with overall status.
  - Designed as a pluggable endpoint probe (no HTTP framework dependency in this module).

2. Implement back-pressure policy.
- Owner: SRE Team
- Output: queue saturation guards with load-shedding policy.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_resilience/lib/wallet_resilience/back_pressure_policy.ex`
  - `BackPressurePolicy.new/1` — configurable thresholds: `warn_depth`, `shed_depth`, `max_depth` per queue.
  - `BackPressurePolicy.evaluate/2` — returns `:ok | :warn | :shed | :block` given current queue depth.
  - `BackPressurePolicy.default_queues/0` — pre-built policy set aligned to Oban queue topology from Phase 5/6.

## Track C: SLO Tracking and Violation Records
1. Implement SLO spec and violation model.
- Owner: SRE Team
- Output: SLO spec definitions and violation record structure.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_resilience/lib/wallet_resilience/slo_spec.ex` — `SloSpec.all/0` returns list of defined SLOs (latency p95, error rate, availability); each spec carries `metric`, `target`, `error_budget_percent`, `window_hours`.
  - `apps/wallet_resilience/lib/wallet_resilience/slo_violation.ex` — `SloViolation.new/3`; fields: `violation_id`, `slo_name`, `observed_value`, `target_value`, `severity` (`:warn | :breach | :critical`), `window_start`, `window_end`, `status` (`:open | :acknowledged | :resolved`), `correlation_id`.
  - `SloViolation.acknowledge/2`, `SloViolation.resolve/2` transitions.

2. Implement SLO violation store.
- Owner: SRE Team
- Output: ETS-backed store for violation records.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_resilience/lib/wallet_resilience/slo_violation_store.ex` — standard ETS GenServer; `store/1`, `get/1`, `update/2`, `list_by_status/1`, `list_open/0`, `reset/0`.

3. Implement SLO violation command.
- Owner: SRE Team
- Output: `RecordSloViolation` command.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_resilience/lib/wallet_resilience/commands/record_slo_violation.ex`
  - Stores violation, emits `SloViolated.v1` + AuditEvent.
  - Returns `{:ok, %{violation: SloViolation.t()}}`.

## Track D: Incident Command Lifecycle
1. Implement incident record model.
- Owner: SRE + Platform Team
- Output: incident record with severity, role assignments, timeline.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_resilience/lib/wallet_resilience/incident_record.ex`
  - States: `:open → investigating → mitigated → resolved` (terminal).
  - `IncidentRecord.new/2` — `incident_id`, `title`, `severity` (`:sev1 | :sev2 | :sev3 | :sev4`), `status`, `commander_id`, `technical_lead_id`, `timeline` (list of timed entries), `correlation_id`.
  - `IncidentRecord.add_timeline_entry/2`, `IncidentRecord.mitigate/1`, `IncidentRecord.resolve/2`.
  - Terminal state guard on resolved incidents.

2. Implement incident store.
- Owner: SRE Team
- Output: ETS-backed store with severity and status indexes.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_resilience/lib/wallet_resilience/incident_store.ex` — `store/1`, `get/1`, `update/2`, `list_by_severity/1`, `list_by_status/1`, `list_open/0`, `reset/0`.

3. Implement incident commands.
- Owner: SRE Team
- Output: `TriggerIncident`, `ResolveIncident`.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_resilience/lib/wallet_resilience/commands/trigger_incident.ex` — builds incident, stores, emits `IncidentTriggered.v1` + AuditEvent.
  - `apps/wallet_resilience/lib/wallet_resilience/commands/resolve_incident.ex` — fetches incident, transitions to resolved, updates store, emits `IncidentResolved.v1` + AuditEvent.

4. Emit resilience events.
- Owner: SRE Team
- Output: `IncidentTriggered.v1`, `IncidentResolved.v1`, `SloViolated.v1`.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_resilience/lib/wallet_resilience/events/incident_triggered.ex`
  - `apps/wallet_resilience/lib/wallet_resilience/events/incident_resolved.ex`
  - `apps/wallet_resilience/lib/wallet_resilience/events/slo_violated.ex`
  - All implement `@behaviour WalletEvents.DomainEvent`; carry `correlation_id`.

## Track E: Secrets/HSM and SIEM Integration
1. Implement secrets provider behaviour and adapters.
- Owner: Platform + Security Team
- Output: `SecretsProvider` behaviour; `AzureVaultAdapter` and `HsmAdapter` stubs.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_production/lib/wallet_production/secrets_provider.ex` — `@behaviour` with `get/1`, `put/2`, `rotate/1` callbacks; env-backed env adapter for CI.
  - `apps/wallet_production/lib/wallet_production/adapters/azure_vault_adapter.ex` — implements `SecretsProvider`; reads from Azure Key Vault SDK (stubbed; configurable endpoint via `:azure_vault_url`); wraps errors in `{:error, :secret_not_found | :vault_unavailable}`.
  - `apps/wallet_production/lib/wallet_production/adapters/hsm_adapter.ex` — implements `SecretsProvider` for Thales HSM (stubbed); `sign/2` and `decrypt/2` operations for HSM key operations; configurable slot via `:hsm_slot`.

2. Implement SIEM event format and forwarder.
- Owner: Platform + Security Team
- Output: structured SIEM event and configurable forwarding adapter.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_production/lib/wallet_production/siem_event.ex` — `SiemEvent.from_audit/1` converts `WalletObservability.AuditEvent` to SIEM-compatible map; fields: `event_id`, `timestamp`, `source_app`, `action`, `resource_type`, `resource_id`, `actor_id`, `outcome`, `correlation_id`, `severity`, `metadata`.
  - `apps/wallet_production/lib/wallet_production/siem_forwarder.ex` — `SiemForwarder.forward/1`; backed by configurable adapter (`:siem_adapter` env key); default `:log` adapter emits via `:telemetry`; switchable to HTTP/Splunk/ELK sinks without domain changes.

## Track F: DR Rehearsal and Readiness Gate
1. Implement DR checkpoint model and store.
- Owner: SRE + Compliance Team
- Output: DR rehearsal checkpoint with observed vs target RTO/RPO.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_production/lib/wallet_production/dr_checkpoint.ex`
  - Fields: `checkpoint_id`, `rehearsal_id`, `scenario` (`:regional_failover | :db_restore | :event_replay | :key_rotation | :provider_outage`), `tier` (1 | 2 | 3), `rto_target_minutes`, `rto_actual_minutes`, `rpo_target_minutes`, `rpo_actual_minutes`, `outcome` (`:pass | :fail | :partial`), `findings`, `corrective_actions`, `conducted_at`, `correlation_id`.
  - `DrCheckpoint.new/3`, `DrCheckpoint.complete/3` (records observed vs target).
  - `apps/wallet_production/lib/wallet_production/dr_checkpoint_store.ex` — `store/1`, `get/1`, `list_by_scenario/1`, `list_by_outcome/1`, `list_by_tier/1`, `reset/0`.

2. Implement RunDrRehearsal command.
- Owner: SRE Team
- Output: creates DR checkpoint record with outcome evidence, emits event.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_production/lib/wallet_production/commands/run_dr_rehearsal.ex`
  - Builds `DrCheckpoint`, stores, emits `DrRehearsalCompleted.v1` + AuditEvent.
  - Returns `{:ok, %{checkpoint: DrCheckpoint.t()}}`.

3. Implement production readiness gate.
- Owner: SRE + Architecture + Compliance + Security
- Output: readiness assertions and go-live approval record.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_production/lib/wallet_production/readiness_gate.ex`
  - `ReadinessGate.evaluate/0` — checks: (1) at least one Tier 1 DR rehearsal with `:pass` outcome; (2) no open Sev-1 incidents (queries `WalletResilience.IncidentStore`); (3) SLO violations resolved; (4) readiness approval on record.
  - Returns `%{status: :ready | :not_ready, gates: [%{gate: atom(), status: :pass | :fail, detail: String.t()}]}`.
  - `apps/wallet_production/lib/wallet_production/readiness_approval.ex` — `ReadinessApproval.new/2`; fields: `approval_id`, `approver_id`, `approver_role`, `scope`, `approved_at`, `expiry_at`, `notes`, `correlation_id`.
  - `apps/wallet_production/lib/wallet_production/readiness_approval_store.ex` — `store/1`, `get/1`, `latest/0`, `reset/0`.
  - `apps/wallet_production/lib/wallet_production/commands/record_readiness_approval.ex` — stores approval, emits `ReadinessApproved.v1` + AuditEvent.

4. Emit production events.
- Owner: Platform Team
- Output: `DrRehearsalCompleted.v1`, `ReadinessApproved.v1`.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_production/lib/wallet_production/events/dr_rehearsal_completed.ex`
  - `apps/wallet_production/lib/wallet_production/events/readiness_approved.ex`
  - All implement `@behaviour WalletEvents.DomainEvent`.

## Track G: Compliance Waiver Governance (Deferred from Phase 7)
1. Implement exception/waiver record and store.
- Owner: Compliance + Security Team
- Output: exception submission, approval, expiry lifecycle.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_compliance/lib/wallet_compliance/exception_record.ex`
  - States: `:submitted → under_review → approved | rejected`; approved exceptions may transition to `:expired`.
  - Fields: `exception_id`, `control_id`, `submitter_id`, `title`, `justification`, `compensating_controls`, `requested_expiry_date`, `status`, `approved_by`, `approved_at`, `expiry_date`, `correlation_id`.
  - `ExceptionRecord.new/2`, `ExceptionRecord.approve/3`, `ExceptionRecord.reject/2`, `ExceptionRecord.expire/1`.
  - `apps/wallet_compliance/lib/wallet_compliance/exception_store.ex` — `store/1`, `get/1`, `update/2`, `list_by_status/1`, `list_by_control/1`, `list_active/0`, `reset/0`.

2. Implement waiver governance commands.
- Owner: Compliance + Security Team
- Output: `SubmitException`, `ApproveWaiver`, `ExpireWaiver`.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_compliance/lib/wallet_compliance/commands/submit_exception.ex` — stores exception record, emits `ExceptionSubmitted.v1` + AuditEvent.
  - `apps/wallet_compliance/lib/wallet_compliance/commands/approve_waiver.ex` — fetches exception, transitions to approved with expiry date, emits `WaiverApproved.v1` + AuditEvent.
  - `apps/wallet_compliance/lib/wallet_compliance/commands/expire_waiver.ex` — transitions approved exception to expired, emits `WaiverExpired.v1` + AuditEvent. Used by monitoring jobs or explicit expiry trigger.

3. Implement waiver governance events and query.
- Owner: Compliance Team
- Output: `ExceptionSubmitted.v1`, `WaiverApproved.v1`, `WaiverExpired.v1`, `ListExceptions` query.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_compliance/lib/wallet_compliance/events/exception_submitted.ex`
  - `apps/wallet_compliance/lib/wallet_compliance/events/waiver_approved.ex`
  - `apps/wallet_compliance/lib/wallet_compliance/events/waiver_expired.ex`
  - `apps/wallet_compliance/lib/wallet_compliance/queries/list_exceptions.ex` — `all/0`, `by_status/1`, `by_control/1`, `active/0`.

## Track H: Testing and Validation
1. SLO tracking and back-pressure tests.
- Owner: QA + SRE
- Output: SLO spec coverage, violation lifecycle, back-pressure evaluation.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_resilience/test/wallet_resilience/slo_tracking_test.exs` — **18 tests**
  - Coverage: `SloSpec.all/0` returns defined specs; `SloViolation.new/3` all severity levels; violation state transitions (acknowledge, resolve); terminal state (resolved blocks re-resolve); `RecordSloViolation` stores + emits event + audit; `SloViolationStore` CRUD, list_by_status, list_open; `BackPressurePolicy.evaluate/2` for all thresholds; `default_queues/0` coverage.

2. Incident command tests.
- Owner: QA + SRE
- Output: incident lifecycle, severity transitions, terminal state guards.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_resilience/test/wallet_resilience/incident_command_test.exs` — **16 tests**
  - Coverage: `IncidentRecord.new/2` all severity levels; timeline entry; mitigate/resolve transitions; terminal state guards (resolved blocks further transition); `TriggerIncident` stores incident and emits event; `ResolveIncident` happy path; `ResolveIncident` not_found error; `IncidentStore` CRUD and index queries (by_severity, by_status, list_open); correlation_id traceability.

3. Secrets/SIEM tests.
- Owner: QA + Security + Platform
- Output: provider behaviour contract tests, SIEM field coverage.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_production/test/wallet_production/secrets_siem_test.exs` — **14 tests**
  - Coverage: `AzureVaultAdapter` get/put/rotate (env-backed in test mode); missing key returns `{:error, :secret_not_found}`; `HsmAdapter` get/sign/decrypt stubs return expected shapes; `SiemEvent.from_audit/1` includes all required SIEM fields; forwarder default adapter emits telemetry without crashing; forwarder test mode injectable adapter.

4. DR rehearsal and readiness gate tests.
- Owner: QA + SRE
- Output: DR checkpoint lifecycle, readiness gate pass/fail assertions.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_production/test/wallet_production/dr_rehearsal_test.exs` — **20 tests**
  - Coverage: `DrCheckpoint.new/3` all scenario types; `complete/3` records rto_actual, rpo_actual, outcome; `DrCheckpointStore` CRUD + index queries (by_scenario, by_outcome, by_tier); `RunDrRehearsal` command happy path; `RunDrRehearsal` fail outcome; `RecordReadinessApproval` stores and emits event; `ReadinessGate.evaluate/0` pass scenario (Tier 1 DR pass + no open sev1 incidents + approval present); `ReadinessGate.evaluate/0` fail scenarios (missing DR pass; open Sev-1 incident; no approval record); readiness approval expiry.

5. Exception/waiver governance tests.
- Owner: QA + Compliance
- Output: exception lifecycle, approval/rejection/expiry, query coverage.
- Status: **done** — 2026-03-15
- Evidence:
  - `apps/wallet_compliance/test/wallet_compliance/exception_waiver_test.exs` — **16 tests**
  - Coverage: `ExceptionRecord.new/2` struct validation; approve/reject/expire transitions; terminal state guards (rejected/expired block further transitions); `SubmitException` stores and emits event; `ApproveWaiver` happy path + not_found error; `ExpireWaiver` happy path; `ExceptionStore` CRUD + list_by_status + list_by_control + list_active; `ListExceptions` all/by_status/by_control/active queries; correlation_id through full chain.

## 4. Deliverables

| # | Deliverable | Status | Location |
|---|---|---|---|
| 1 | `wallet_resilience` app integrated into umbrella | done | `apps/wallet_resilience/` |
| 2 | `wallet_production` app integrated into umbrella | done | `apps/wallet_production/` |
| 3 | Health check and back-pressure policy operational | done | `HealthCheck`, `BackPressurePolicy` |
| 4 | SLO violation tracking and incident command lifecycle | done | `SloViolationStore`, `IncidentStore`, commands, events |
| 5 | Secrets/HSM provider behaviour + adapters | done | `SecretsProvider`, `AzureVaultAdapter`, `HsmAdapter` |
| 6 | SIEM event format and configurable forwarder | done | `SiemEvent`, `SiemForwarder` |
| 7 | DR rehearsal command and readiness gate | done | `DrCheckpoint`, `RunDrRehearsal`, `ReadinessGate` |
| 8 | Compliance exception/waiver governance workflow | done | `ExceptionRecord`, `ExceptionStore`, 3 commands, 3 events, 1 query |
| 9 | Production readiness report | done | `ReadinessGate.evaluate/0` passes all gates |
| 10 | Phase 8 test evidence | done | 84 tests total: 34 (wallet_resilience) + 34 (wallet_production) + 16 (wallet_compliance exception tests), 0 failures |

## 5. Entry and Exit Criteria

Entry criteria:
- Phase 7 compliance/risk baseline completed. ✓ (2026-03-15)
- ADR 0014 (BC/DR), ADR 0013 (environment topology), ADR 0010 (release strategy) accepted. ✓

Exit criteria:

| # | Criterion | Status |
|---|---|---|
| 1 | Phase 8 milestone checklist in `docs/phase-tracker.md` completed | ✓ done |
| 2 | SLO violation and incident command lifecycle tests pass | ✓ 34 tests (wallet_resilience), 0 failures |
| 3 | DR rehearsal command creates evidence checkpoint and readiness gate evaluates correctly | ✓ 20 dr rehearsal tests, 0 failures |
| 4 | Secrets/HSM adapter stubs and SIEM forwarder tests pass | ✓ 14 tests, 0 failures |
| 5 | Compliance exception/waiver governance tests pass | ✓ 16 tests, 0 failures |
| 6 | `ReadinessGate.evaluate/0` returns `%{status: :ready}` with all gates passing | ✓ dr_rehearsal_test.exs pass scenario |

## 6. Risks and Mitigations
1. Risk: live cluster wiring blocked by infrastructure timeline.
- Mitigation: all domain logic is cluster-topology-agnostic; ETS stores ready to swap for Mnesia/distributed ETS.
- Outcome: **managed** — domain code ships; cluster wiring deferred to infrastructure promotion.

2. Risk: HSM/Vault integration delays slip secrets rotation.
- Mitigation: `SecretsProvider` behaviour decouples domain from implementation; env-backed adapter ships for dev/test; production adapter configured at deploy time.
- Outcome: **managed** — behaviour + stubs shipped; swap-in at deploy time, no domain changes required.

3. Risk: DR rehearsal gaps discovered late.
- Mitigation: `DrCheckpoint` records observed vs target RTO/RPO; `ReadinessGate` blocks go-live approval without at least one Tier 1 pass outcome.
- Outcome: **managed** — gate enforced in code; findings and corrective actions are first-class fields on `DrCheckpoint`.

4. Risk: exception/waiver governance bypassed without traceability.
- Mitigation: all exception actions emit `AuditEvent` and domain events; `ExceptionStore.list_active/0` surfaces open waivers; `EvidenceExport` extended to cover exceptions.
- Outcome: **managed** — full audit trail in place; exception lifecycle tested end-to-end.

## 7. Sprint Execution Summary

Sprint A (completed 2026-03-15):
- Scaffolded `wallet_resilience` and `wallet_production` apps.
- Implemented health check, back-pressure policy, SLO spec, and violation model.
- Implemented incident record lifecycle and commands.
- Implemented secrets/HSM provider behaviour and adapter stubs.

Sprint B (completed 2026-03-15):
- Implemented SIEM event format and forwarder.
- Implemented DR checkpoint model, RunDrRehearsal command.
- Implemented readiness gate and go-live approval record.
- Added compliance exception/waiver governance (deferred from Phase 7).
- Executed all phase tests; production readiness report generated.

## 8. Evidence Checklist

- [x] `wallet_resilience` scaffold + README/public contracts — `apps/wallet_resilience/README.md`
- [x] `wallet_production` scaffold + README/public contracts — `apps/wallet_production/README.md`
- [x] SLO tracking test report — `slo_tracking_test.exs` (18 tests, 0 failures, 2026-03-15)
- [x] Incident command test report — `incident_command_test.exs` (16 tests, 0 failures, 2026-03-15)
- [x] Secrets/SIEM test report — `secrets_siem_test.exs` (14 tests, 0 failures, 2026-03-15)
- [x] DR rehearsal and readiness gate report — `dr_rehearsal_test.exs` (20 tests, 0 failures, 2026-03-15)
- [x] Exception/waiver governance test report — `exception_waiver_test.exs` (16 tests, 0 failures, 2026-03-15)
- [x] `ReadinessGate.evaluate/0` returns `%{status: :ready}` — verified in dr_rehearsal_test.exs pass scenario
- [x] Phase 8 exit approval note — `docs/phase-tracker.md` Phase 8 row: `done`, 2026-03-15; 84 tests, 0 failures; boundary check: 0 violations