test: make embedded-postgres per-process so concurrent CI runs don't collide

A push to main and its version tag fire two CI runs for the same commit. Both ran
`go test ./...`, which starts embedded-postgres on a FIXED port (54329/54330) and
a shared data dir. -p 1 serialises packages WITHIN a run, not across two
concurrent runs — so when the two runs overlapped they collided on the port/data
dir and BOTH failed the Lint/Test job (no image built). Prior commits passed only
because their two runs happened not to overlap.

Derive the port and runtime/data dirs from the PID; share only CachePath so the
PG archive downloads once. Proven: two concurrent `go test` of the store package
now both pass. Unblocks the v0.21.0 (Pillar A) build.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/adapters/store/store_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"os"
+	"path/filepath"
 	"testing"
 
 	embeddedpostgres "github.com/fergusstrange/embedded-postgres"
@@ -24,11 +25,22 @@ var _ ports.Sink = (*store.Store)(nil)
 var dsn string
 
 func TestMain(m *testing.M) {
-	const port = 54329
+	// Port + runtime/data dirs are per-process (PID-derived) so two concurrent
+	// `go test` invocations — e.g. a push-run and a tag-run firing together in CI —
+	// don't collide on a fixed port or a shared data dir (which silently failed
+	// both runs). CachePath is shared so the PG archive is downloaded once, not
+	// per process. Base 54000 keeps this package's range distinct from web's.
+	port := uint32(54000 + os.Getpid()%1000)
 	dsn = fmt.Sprintf("postgres://postgres:postgres@localhost:%d/postgres?sslmode=disable", port)
 
+	rt := filepath.Join(os.TempDir(), fmt.Sprintf("tapir-epg-store-%d", os.Getpid()))
 	pg := embeddedpostgres.NewDatabase(
-		embeddedpostgres.DefaultConfig().Port(port),
+		embeddedpostgres.DefaultConfig().
+			Port(port).
+			RuntimePath(rt).
+			DataPath(filepath.Join(rt, "data")).
+			BinariesPath(filepath.Join(rt, "bin")).
+			CachePath(filepath.Join(os.TempDir(), "tapir-epg-cache")),
 	)
 	if err := pg.Start(); err != nil {
 		fmt.Fprintf(os.Stderr, "embedded-postgres start: %v\n", err)
@@ -40,6 +52,7 @@ func TestMain(m *testing.M) {
 	if err := pg.Stop(); err != nil {
 		fmt.Fprintf(os.Stderr, "embedded-postgres stop: %v\n", err)
 	}
+	_ = os.RemoveAll(rt)
 	os.Exit(code)
 }
 

internal/web/handlers_test.go

@@ -7,6 +7,7 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"os"
+	"path/filepath"
 	"strings"
 	"testing"
 	"time"
@@ -26,10 +27,22 @@ import (
 var dsn string
 
 func TestMain(m *testing.M) {
-	const port = 54330 // distinct from the store package's embedded PG (54329)
+	// Per-process port + dirs so concurrent `go test` runs (e.g. a push-run and a
+	// tag-run in CI) never collide on a fixed port or shared data dir. Base 55000
+	// keeps web's range distinct from the store package (54000). Shared CachePath
+	// downloads the PG archive once.
+	port := uint32(55000 + os.Getpid()%1000)
 	dsn = fmt.Sprintf("postgres://postgres:postgres@localhost:%d/postgres?sslmode=disable", port)
 
-	pg := embeddedpostgres.NewDatabase(embeddedpostgres.DefaultConfig().Port(port))
+	rt := filepath.Join(os.TempDir(), fmt.Sprintf("tapir-epg-web-%d", os.Getpid()))
+	pg := embeddedpostgres.NewDatabase(
+		embeddedpostgres.DefaultConfig().
+			Port(port).
+			RuntimePath(rt).
+			DataPath(filepath.Join(rt, "data")).
+			BinariesPath(filepath.Join(rt, "bin")).
+			CachePath(filepath.Join(os.TempDir(), "tapir-epg-cache")),
+	)
 	if err := pg.Start(); err != nil {
 		fmt.Fprintf(os.Stderr, "embedded-postgres start: %v\n", err)
 		os.Exit(1)
@@ -38,6 +51,7 @@ func TestMain(m *testing.M) {
 	if err := pg.Stop(); err != nil {
 		fmt.Fprintf(os.Stderr, "embedded-postgres stop: %v\n", err)
 	}
+	_ = os.RemoveAll(rt)
 	os.Exit(code)
 }