diff --git a/cmd/bsdaily/main.go b/cmd/bsdaily/main.go
index f3ba402..a16ded0 100644
--- a/cmd/bsdaily/main.go
+++ b/cmd/bsdaily/main.go
@@ -1,10 +1,13 @@
 package main
 
 import (
+	"fmt"
 	"log/slog"
 	"os"
+	"time"
 
 	"git.eeqj.de/sneak/bsdaily/internal/bsdaily"
+	"github.com/spf13/cobra"
 )
 
 func main() {
@@ -13,9 +16,33 @@ func main() {
 	}))
 	slog.SetDefault(logger)
 
-	if err := bsdaily.Run(); err != nil {
-		slog.Error("fatal error", "error", err)
+	var dateFlag string
+
+	rootCmd := &cobra.Command{
+		Use:   "bsdaily",
+		Short: "Extract a single day's data from the latest daily snapshot",
+		SilenceUsage: true,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			var targetDate *time.Time
+			if dateFlag != "" {
+				t, err := time.Parse("2006-01-02", dateFlag)
+				if err != nil {
+					return fmt.Errorf("invalid date %q (expected YYYY-MM-DD): %w", dateFlag, err)
+				}
+				targetDate = &t
+			}
+
+			if err := bsdaily.Run(targetDate); err != nil {
+				return err
+			}
+			slog.Info("completed successfully")
+			return nil
+		},
+	}
+
+	rootCmd.Flags().StringVarP(&dateFlag, "date", "d", "", "target date to extract (YYYY-MM-DD); defaults to snapshot date minus one day")
+
+	if err := rootCmd.Execute(); err != nil {
 		os.Exit(1)
 	}
-	slog.Info("completed successfully")
 }
diff --git a/go.mod b/go.mod
index 7abaa7d..07e7bb1 100644
--- a/go.mod
+++ b/go.mod
@@ -10,9 +10,12 @@ require (
 require (
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/google/uuid v1.6.0 // indirect
+	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/ncruces/go-strftime v1.0.0 // indirect
 	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
+	github.com/spf13/cobra v1.10.2 // indirect
+	github.com/spf13/pflag v1.0.9 // indirect
 	golang.org/x/exp v0.0.0-20251023183803-a4bb9ffd2546 // indirect
 	modernc.org/libc v1.67.6 // indirect
 	modernc.org/mathutil v1.7.1 // indirect
diff --git a/go.sum b/go.sum
index 27915ba..bc888c7 100644
--- a/go.sum
+++ b/go.sum
@@ -1,3 +1,4 @@
+github.com/cpuguy83/go-md2man/v2 v2.0.6/go.mod h1:oOW0eioCTA6cOiMLiUPZOpcVxMig6NIQQ7OS05n1F4g=
 github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
 github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
 github.com/google/pprof v0.0.0-20250317173921-a4b03ec1a45e h1:ijClszYn+mADRFY17kjQEVQ1XRhq2/JR1M3sGqeJoxs=
@@ -6,12 +7,20 @@ github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/hashicorp/golang-lru/v2 v2.0.7 h1:a+bsQ5rvGLjzHuww6tVxozPZFVghXaHOwFs4luLUK2k=
 github.com/hashicorp/golang-lru/v2 v2.0.7/go.mod h1:QeFd9opnmA6QUJc5vARoKUSoFhyfM2/ZepoAG6RGpeM=
+github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
+github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
 github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
 github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
 github.com/ncruces/go-strftime v1.0.0 h1:HMFp8mLCTPp341M/ZnA4qaf7ZlsbTc+miZjCLOFAw7w=
 github.com/ncruces/go-strftime v1.0.0/go.mod h1:Fwc5htZGVVkseilnfgOVb9mKy6w1naJmn9CehxcKcls=
 github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec h1:W09IVJc94icq4NjY3clb7Lk8O1qJ8BdBEF8z0ibU0rE=
 github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec/go.mod h1:qqbHyh8v60DhA7CoWK5oRCqLrMHRGoxYCSS9EjAz6Eo=
+github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/spf13/cobra v1.10.2 h1:DMTTonx5m65Ic0GOoRY2c16WCbHxOOw6xxezuLaBpcU=
+github.com/spf13/cobra v1.10.2/go.mod h1:7C1pvHqHw5A4vrJfjNwvOdzYu0Gml16OCs2GRiTUUS4=
+github.com/spf13/pflag v1.0.9 h1:9exaQaMOCwffKiiiYk6/BndUBv+iRViNW+4lEMi0PvY=
+github.com/spf13/pflag v1.0.9/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+go.yaml.in/yaml/v3 v3.0.4/go.mod h1:DhzuOOF2ATzADvBadXxruRBLzYTpT36CKvDb3+aBEFg=
 golang.org/x/exp v0.0.0-20251023183803-a4bb9ffd2546 h1:mgKeJMpvi0yx/sU5GsxQ7p6s2wtOnGAHZWCHUM4KGzY=
 golang.org/x/exp v0.0.0-20251023183803-a4bb9ffd2546/go.mod h1:j/pmGrbnkbPtQfxEe5D0VQhZC6qKbfKifgD0oM7sR70=
 golang.org/x/mod v0.29.0 h1:HV8lRxZC4l2cr3Zq1LvtOsi/ThTgWnUk/y64QSs8GwA=
@@ -23,6 +32,7 @@ golang.org/x/sys v0.41.0 h1:Ivj+2Cp/ylzLiEU89QhWblYnOE9zerudt9Ftecq2C6k=
 golang.org/x/sys v0.41.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
 golang.org/x/tools v0.38.0 h1:Hx2Xv8hISq8Lm16jvBZ2VQf+RLmbd7wVUsALibYI/IQ=
 golang.org/x/tools v0.38.0/go.mod h1:yEsQ/d/YK8cjh0L6rZlY8tgtlKiBNTL14pGDJPJpYQs=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 modernc.org/cc/v4 v4.27.1 h1:9W30zRlYrefrDV2JE2O8VDtJ1yPGownxciz5rrbQZis=
 modernc.org/cc/v4 v4.27.1/go.mod h1:uVtb5OGqUKpoLWhqwNQo/8LwvoiEBLvZXIQ/SmO6mL0=
 modernc.org/ccgo/v4 v4.30.1 h1:4r4U1J6Fhj98NKfSjnPUN7Ze2c6MnAdL0hWw6+LrJpc=
diff --git a/internal/bsdaily/run.go b/internal/bsdaily/run.go
index 08dd826..6a8cdba 100644
--- a/internal/bsdaily/run.go
+++ b/internal/bsdaily/run.go
@@ -5,16 +5,22 @@ import (
 	"log/slog"
 	"os"
 	"path/filepath"
+	"time"
 )
 
-func Run() error {
+func Run(targetDate *time.Time) error {
 	snapshotDir, snapshotDate, err := FindLatestDailySnapshot()
 	if err != nil {
 		return fmt.Errorf("finding latest snapshot: %w", err)
 	}
 	slog.Info("found latest daily snapshot", "dir", snapshotDir, "snapshot_date", snapshotDate.Format("2006-01-02"))
 
-	targetDay := snapshotDate.AddDate(0, 0, -1)
+	var targetDay time.Time
+	if targetDate != nil {
+		targetDay = *targetDate
+	} else {
+		targetDay = snapshotDate.AddDate(0, 0, -1)
+	}
 	slog.Info("target day for extraction", "date", targetDay.Format("2006-01-02"))
 
 	// Check if output already exists