feat: each test package runs on its own database

agent, db, server and evidence serialized on one shared test database via an advisory lock, while evidence, llmrec and traffic-style packages could still run against it in parallel; under full-suite load that window produced a real SQLSTATE 40P01 deadlock in the blackboard direct-source test. TestMain in every PG-using package now rewrites ARTEX_PG_DSN to a per-package database (created automatically by ensureDatabase), so packages neither contend nor need to serialize; the advisory lock stays as an in-package safety net. llmrec gains the TestMain it lacked, which also gives its requires-isolated-DSN tests a truly isolated database inside ./... runs.

agent/testmain_test.go

@@ -13,6 +13,10 @@ import (
 // agent test suite so cross-package DELETE cleanup races with db/server
 // packages are avoided when running `go test ./...`.
 func TestMain(m *testing.M) {
+	// Own database per package (#80): with separate databases, packages stop
+	// contending on shared tables and the advisory lock below stops
+	// serializing go test ./... across packages.
+	db.SuffixTestDatabase("agent")
 	dsn, _, err := db.DSN()
 	if err != nil {
 		os.Exit(m.Run())

db/db.go

@@ -10,6 +10,7 @@ import (
 	"errors"
 	"fmt"
 	"net/url"
+	"os"
 	"strings"
 	"time"
 
@@ -96,6 +97,26 @@ func DSN() (dsn, source string, err error) {
 	return config.PostgresDSN()
 }
 
+// SuffixTestDatabase rewrites the ARTEX_PG_DSN environment variable so its
+// database name carries the given suffix (artex -> artex_agent). Called from
+// package TestMain functions so every go test package runs against its own
+// database: parallel package processes then cannot contend on the same tables
+// (the under-load deadlock family, #80). No-op when ARTEX_PG_DSN is unset —
+// config-file and production paths are untouched. Open creates the suffixed
+// database automatically (ensureDatabase).
+func SuffixTestDatabase(suffix string) {
+	v := strings.TrimSpace(os.Getenv("ARTEX_PG_DSN"))
+	if v == "" {
+		return
+	}
+	u, err := url.Parse(v)
+	if err != nil || u.Path == "" || u.Path == "/" {
+		return
+	}
+	u.Path = "/" + strings.TrimPrefix(u.Path, "/") + "_" + suffix
+	_ = os.Setenv("ARTEX_PG_DSN", u.String())
+}
+
 // DB wraps the shared *sql.DB. PG handles its own connection pool + concurrency
 // (MVCC), so unlike the old SQLite store there is no process-wide write mutex.
 type DB struct{ *sql.DB }

db/testmain_test.go

@@ -14,6 +14,10 @@ import (
 // avoid cross-package cleanup races (e.g. DELETE FROM assets WHERE id > X
 // from one package deleting assets created by another).
 func TestMain(m *testing.M) {
+	// Own database per package (#80): with separate databases, packages stop
+	// contending on shared tables and the advisory lock below stops
+	// serializing go test ./... across packages.
+	SuffixTestDatabase("db")
 	dsn, _, err := DSN()
 	if err != nil {
 		// No DB configured — tests that need PG will skip themselves.

evidence/testmain_test.go

@@ -11,6 +11,9 @@ import (
 // Initialize an explicitly configured fresh database before taking the same
 // suite lock as db, agent and server. Hold it on one pinned connection.
 func TestMain(m *testing.M) {
+	// Own database per package (#80): stop contending on the shared tables of
+	// a single test database during parallel ./... runs.
+	db.SuffixTestDatabase("evidence")
 	if os.Getenv("ARTEX_PG_DSN") == "" {
 		os.Exit(m.Run())
 	}

llmrec/testmain_test.go

@@ -0,0 +1,16 @@
+package llmrec
+
+import (
+	"os"
+	"testing"
+
+	"github.com/Autumn-27/artex/db"
+)
+
+// Run against this package's own database (db.SuffixTestDatabase, #80): the
+// recorder tests require an isolated ARTEX_PG_DSN, and the suffix gives them
+// one even inside a full parallel ./... run.
+func TestMain(m *testing.M) {
+	db.SuffixTestDatabase("llmrec")
+	os.Exit(m.Run())
+}

server/testmain_test.go

@@ -13,6 +13,10 @@ import (
 // server test suite so cross-package DELETE cleanup races with db/agent
 // packages are avoided when running `go test ./...`.
 func TestMain(m *testing.M) {
+	// Own database per package (#80): with separate databases, packages stop
+	// contending on shared tables and the advisory lock below stops
+	// serializing go test ./... across packages.
+	db.SuffixTestDatabase("server")
 	dsn, _, err := db.DSN()
 	if err != nil {
 		os.Exit(m.Run())