feat: Delete unused Postgres backend (dead code) - Issue #41

[anota-fernandocosta]

Description

Deletes the unused Postgres backend implementation from the codebase. The Postgres backend implemented the same Requests interface as MongoDB but was never wired up in production (the docker-compose Postgres service was commented out).

Changes

Deleted (US-001 through US-008):

• US-001: Deleted entire api/db/postgres/ directory (5 files: postgres_handler.go, sql.go, types.go, sql_test.go, postgres_suite_test.go)
• US-002: Deleted api/db/psqlretriever.go (SQLJSONRetrieve adapter with lib/pq dependency)
• US-003: Deleted api/db/postgres.go and api/db/postgres_test.go (PostgresRequests implementation + tests)
• US-004: Cleaned api/db/types.go — removed Postgres-only types (DataGenerator, SQLJSONRetrieve, PostgresRequests); preserved Requests, MongoRequests, JSON, JSONCaller
• US-005: Simplified api/context/context.go::GetDB — removed Postgres branch, now always returns &db.MongoRequests{}
• US-006: Deleted deployments/dockerfiles/postgres.Dockerfile and deployments/huskyci.sql; removed commented-out Postgres service from deployments/docker-compose.yml
• US-007: Updated CLAUDE.md — states MongoDB is the supported production store, db.Requests preserved for abstraction/testability
• US-008: Ran go mod tidy in api/ — removed github.com/lib/pq from go.mod and go.sum

What remains:

• db.Requests interface (api/db/huskydb.go) — preserved for abstraction and testability
• MongoRequests struct (api/db/types.go) — the active MongoDB implementation
• All behavioral contracts intact (client exit code 190, token rejection, input validators, scanner command substitution, K8s WaitPod)

Testing

• cd api && go vet ./... — passes cleanly
• cd api && go test -race -count=1 ./... — all 10 test packages pass, no race conditions
• Per-module independence verified — client/go.mod and cli/go.mod unchanged

Closes #41

[anota-fernandocosta]

Review: Approve ✅

This is a clean, well-executed dead code removal. All 8 user stories are completed, the diff is focused, and no behavioral contracts are broken.

What was removed (10 files, ~3,000 lines):

• api/db/postgres/ (5 files): innermost Postgres implementation
• api/db/postgres.go + api/db/postgres_test.go: PostgresRequests and tests
• api/db/psqlretriever.go: SQLJSONRetrieve adapter with lib/pq dependency
• deployments/dockerfiles/postgres.Dockerfile + deployments/huskyci.sql: deployment artifacts
• Commented-out Postgres service in docker-compose.yml

What was modified correctly:

• api/context/context.go: Postgres import + entire GetDB Postgres branch removed. Function now unconditionally returns &db.MongoRequests{}. strings import correctly preserved (still used elsewhere).
• api/db/types.go: DataGenerator, SQLJSONRetrieve, PostgresRequests removed. Requests, MongoRequests, JSON, JSONCaller preserved. time import correctly preserved (used in Requests interface).
• api/go.mod + go.sum: github.com/lib/pq removed. golang.org/x/net correctly moved to indirect (only needed by k8s.io deps now).
• CLAUDE.md: Updated to state MongoDB is the supported production store, db.Requests preserved for abstraction/testability.
• deployments/docker-compose.yml: Postgres service block fully removed.

Incidental gofmt fixes (all benign):

• api/auth/types.go, api/context/context_test.go, api/context/gitleaks_env_test.go, api/securitytest/gitleaks_severity.go, api/securitytest/run_test.go, api/securitytest/runner.go, api/securitytest/securitycodescan.go, api/types/types.go: formatting/alignment fixes

CI: All 8 checks pass

Build & Test (api, cli, client) ✅ | Lint ✅ | Docker Build (api, client) ✅ | Deployment shell ✅ | Gitleaks ✅

Non-blocking note:

JSON interface, JSONCaller struct, and api/db/jsoncaller.go are no longer referenced by any production or test code after the Postgres removal. The task spec preserves them — a reasonable choice. Worth considering for a future cleanup pass if they remain unused.

Verdict:

No bugs, no regressions, no missed references. The removal is thorough and the diff is clean. Approving.