Move the archive files into their own package (closes #541)

The SQLite archive files the database target writes are now managed by
internal/archive: file names, rotation, the writer of each target,
pruning, renames, the gzipped JSON export, the idle sweep, and the
rename lock, which was Handlers.renameMu. The database target stays in
internal/delivery and writes through archive.Writers; the engine still
closes the writers when it stops, so the stop order is unchanged. The
handlers take the rename lock from archive.Archives.RenameLock, and
rename and evict through archive.Archives.

Exported names drop their Archive prefix in the new package. The tests
moved with the code; the two that check a delivery's recorded attempt
stay in delivery.

Model: opus-5-5

cmd/webhooker/main.go

@@ -10,6 +10,7 @@ import (
 
 	"go.uber.org/fx"
 	"go.uber.org/fx/fxevent"
+	"sneak.berlin/go/webhooker/internal/archive"
 	"sneak.berlin/go/webhooker/internal/config"
 	"sneak.berlin/go/webhooker/internal/database"
 	"sneak.berlin/go/webhooker/internal/datadir"
@@ -49,7 +50,7 @@ import (
 // before the server may already have spent.
 //
 // This does not make the database close unconditional: the
-// ArchiveSweeper and RetentionReaper hooks run before the server.
+// archive.Sweeper and RetentionReaper hooks run before the server.
 // What they spend comes out of the drain first, but past 3s it comes
 // out of the reserve, and they can consume the whole budget.
 const stopTimeout = 5 * time.Second
@@ -188,8 +189,8 @@ func newApp() *fx.App {
 		fx.Provide(
 			globals.New,
 			logger.New,
-			// The plain logger the session, the middleware and the
-			// webhook database manager take.
+			// The plain logger the session, the middleware, the
+			// webhook database manager and the archive writers take.
 			func(l *logger.Logger) *slog.Logger { return l.Get() },
 			config.New,
 			database.New,
@@ -208,14 +209,15 @@ func newApp() *fx.App {
 			// disagree about a destination.
 			delivery.NewGuard,
 			delivery.New,
-			delivery.NewArchiveSweeper,
+			archive.NewWriters,
+			archive.NewSweeper,
 			// Wire *delivery.Engine as delivery.Notifier so the
 			// webhook handler can notify the engine of new deliveries.
 			func(e *delivery.Engine) delivery.Notifier { return e },
-			// Wire *delivery.Engine as delivery.Archives so deleting
+			// Wire *archive.Writers as archive.Archives so deleting
 			// or renaming a webhook or target reaches its archive
 			// files.
-			func(e *delivery.Engine) delivery.Archives { return e },
+			func(w *archive.Writers) archive.Archives { return w },
 			// Wire *delivery.Engine as delivery.CircuitBreakers so
 			// the pages can show a target whose deliveries are
 			// paused.
@@ -227,7 +229,7 @@ func newApp() *fx.App {
 				*server.Server,
 				*delivery.Engine,
 				*database.RetentionReaper,
-				*delivery.ArchiveSweeper,
+				*archive.Sweeper,
 			) {
 			},
 		),

cmd/webhooker/main_test.go

@@ -252,7 +252,7 @@ const tailHeadroom = 2 * time.Second
 // can produce, since a shorter drain leaves the flush more room and
 // the worst case is not necessarily at either extreme.
 //
-// Nor does the hook start on a full budget: the ArchiveSweeper and
+// Nor does the hook start on a full budget: the archive.Sweeper and
 // RetentionReaper hooks run before it, and whatever they spent is
 // gone. The outer sweep walks every amount they can spend. Once they
 // have eaten into the headroom themselves, the hook must spend