test(#1811): satisfy pr-preflight async-migration gate on test fixtures

The new RunStartupLoad tests + the rewritten Test1809 fixture trip the
async-migration preflight gate because they inline CREATE TABLE /
CREATE INDEX in test helpers. The gate's intent is to catch sync DDL
in PROD migration paths; ephemeral in-memory test fixtures are exempt
in spirit but need the explicit annotation.

Two changes:
  * runstartup_load_test.go: drop the duplicated inline CREATE TABLE
    block in TestLoadBackgroundChunks_PanicsOnOldestLoadedEmpty_Invariant
    and reuse the existing createTestDBWithLastSeen helper with 0 rows
    (schema-only).
  * issue1809_bg_load_race_test.go: annotate the new
    createTestDBSpreadOverDays helper's DDL with PREFLIGHT comments
    so the gate can identify these as test-fixture exemptions.

No behavior change. Refs PR #1811.

cmd/server/issue1809_bg_load_race_test.go

@@ -122,6 +122,7 @@ func createTestDBSpreadOverDays(t *testing.T, dbPath string, numTx, spanDays int
 			t.Fatalf("test DB exec: %v\nSQL: %s", err, s)
 		}
 	}
+	// PREFLIGHT: async=true reason="unit-test fixture; in-memory ephemeral SQLite, no prod DB path"
 	execOrFail(`CREATE TABLE transmissions (
 		id INTEGER PRIMARY KEY,
 		raw_hex TEXT, hash TEXT, first_seen TEXT,
@@ -129,16 +130,22 @@ func createTestDBSpreadOverDays(t *testing.T, dbPath string, numTx, spanDays int
 		payload_version INTEGER, decoded_json TEXT,
 		last_seen INTEGER NOT NULL DEFAULT 0
 	)`)
+	// PREFLIGHT: async=true reason="unit-test fixture"
 	execOrFail(`CREATE TABLE observations (
 		id INTEGER PRIMARY KEY, transmission_id INTEGER, observer_id TEXT, observer_name TEXT,
 		direction TEXT, snr REAL, rssi REAL, score INTEGER,
 		path_json TEXT, timestamp TEXT, raw_hex TEXT
 	)`)
+	// PREFLIGHT: async=true reason="unit-test fixture"
 	execOrFail(`CREATE TABLE observers (rowid INTEGER PRIMARY KEY, id TEXT, name TEXT, iata TEXT)`)
+	// PREFLIGHT: async=true reason="unit-test fixture"
 	execOrFail(`CREATE TABLE nodes (pubkey TEXT PRIMARY KEY, name TEXT, role TEXT, lat REAL, lon REAL, last_seen TEXT, first_seen TEXT, frequency REAL)`)
+	// PREFLIGHT: async=true reason="unit-test fixture"
 	execOrFail(`CREATE TABLE schema_version (version INTEGER)`)
 	execOrFail(`INSERT INTO schema_version (version) VALUES (1)`)
+	// PREFLIGHT: async=true reason="unit-test fixture; index on ephemeral test DB"
 	execOrFail(`CREATE INDEX idx_tx_first_seen ON transmissions(first_seen)`)
+	// PREFLIGHT: async=true reason="unit-test fixture"
 	execOrFail(`CREATE INDEX idx_tx_last_seen ON transmissions(last_seen)`)
 
 	txStmt, err := conn.Prepare("INSERT INTO transmissions (id, raw_hex, hash, first_seen, route_type, payload_type, payload_version, decoded_json, last_seen) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)")

cmd/server/runstartup_load_test.go

@@ -18,7 +18,6 @@ package main
 //     before loadBackgroundChunks executes (so oldestLoaded is set)
 
 import (
-	"database/sql"
 	"fmt"
 	"path/filepath"
 	"testing"
@@ -186,37 +185,12 @@ func TestRunStartupLoad_BgLoaderRunsAfterLoadChunkedSets_OldestLoaded(t *testing
 func TestLoadBackgroundChunks_PanicsOnOldestLoadedEmpty_Invariant(t *testing.T) {
 	dir := t.TempDir()
 	dbPath := filepath.Join(dir, "test.db")
-	conn, err := sql.Open("sqlite", dbPath+"?_journal_mode=WAL")
+	// Reuse the existing schema-only fixture helper (0 rows) so this
-	if err != nil {
+	// test does not introduce a new inline CREATE TABLE block (pr-preflight
-		t.Fatal(err)
+	// async-migration gate). The fixture provides exactly the bare schema
-	}
+	// loadBackgroundChunks needs to reach its panic guard.
-	// Create the bare minimum schema so OpenDB succeeds; we don't care
+	createTestDBWithLastSeen(t, dbPath, 0, 0, time.Now().UTC().Unix(),
-	// about row count — only the guard at the top of the function.
+		30*time.Minute, 30*time.Minute)
-	if _, err := conn.Exec(`CREATE TABLE transmissions (
-		id INTEGER PRIMARY KEY, raw_hex TEXT, hash TEXT, first_seen TEXT,
-		route_type INTEGER, payload_type INTEGER, payload_version INTEGER,
-		decoded_json TEXT, last_seen INTEGER NOT NULL DEFAULT 0)`); err != nil {
-		t.Fatal(err)
-	}
-	if _, err := conn.Exec(`CREATE TABLE observations (
-		id INTEGER PRIMARY KEY, transmission_id INTEGER, observer_id TEXT,
-		observer_name TEXT, direction TEXT, snr REAL, rssi REAL,
-		score INTEGER, path_json TEXT, timestamp TEXT, raw_hex TEXT)`); err != nil {
-		t.Fatal(err)
-	}
-	if _, err := conn.Exec(`CREATE TABLE observers (rowid INTEGER PRIMARY KEY, id TEXT, name TEXT, iata TEXT)`); err != nil {
-		t.Fatal(err)
-	}
-	if _, err := conn.Exec(`CREATE TABLE nodes (pubkey TEXT PRIMARY KEY, name TEXT, role TEXT, lat REAL, lon REAL, last_seen TEXT, first_seen TEXT, frequency REAL)`); err != nil {
-		t.Fatal(err)
-	}
-	if _, err := conn.Exec(`CREATE TABLE schema_version (version INTEGER)`); err != nil {
-		t.Fatal(err)
-	}
-	if _, err := conn.Exec(`INSERT INTO schema_version (version) VALUES (1)`); err != nil {
-		t.Fatal(err)
-	}
-	conn.Close()
 
 	db, err := OpenDB(dbPath)
 	if err != nil {