diff --git a/.gitea/workflows/release.yml b/.gitea/workflows/release.yml
index 65f05aa..7a06a0f 100644
--- a/.gitea/workflows/release.yml
+++ b/.gitea/workflows/release.yml
@@ -30,7 +30,8 @@ jobs:
           CGO_ENABLED: 1
         run: |
           mkdir -p dist
-          go build -trimpath -ldflags="-s -w" \
+          go build -trimpath \
+            -ldflags="-s -w -X main.version=${{ github.ref_name }}" \
             -o dist/patterm-${{ github.ref_name }}-linux-amd64 \
             ./cmd/patterm
 
diff --git a/CHANGELOG.md b/CHANGELOG.md
index bb9ce0b..ddbfdd9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,21 @@ loosely follows [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
 
+### Added
+- `patterm --version` prints the build version, git commit, and build
+  date (e.g. `patterm v0.0.1 (commit abc1234, built 2026-05-14)`). The
+  version string is injected by the build (`make patterm` derives it
+  from `git describe`; the release workflow injects the pushed tag).
+  Commit and date come from the Go toolchain's embedded VCS info, so
+  nothing has to be bumped by hand.
+
+### Changed
+- CLI flag parsing switched from Go's stdlib `flag` to `spf13/pflag`.
+  `--project` (and the internal `--socket` / `--identity` /
+  `--scenario` / `--patterm-bin` flags) are now the only accepted form
+  — single-hyphen long flags like `-project` are rejected. Help output
+  renders the canonical `--flag` form.
+
 ## [0.0.1] - 2026-05-14
 
 ### Fixed
diff --git a/Makefile b/Makefile
index 799570a..2b62e4d 100644
--- a/Makefile
+++ b/Makefile
@@ -32,11 +32,13 @@ deps-build: $(INSTALL)/lib/libghostty-vt.a
 clean-deps:
 	rm -rf $(SOURCE) $(INSTALL)
 
+VERSION ?= $(shell git describe --tags --always --dirty 2>/dev/null || echo dev)
+
 spike: deps
 	go build -o ./bin/spike ./cmd/spike
 
 patterm: deps
-	go build -o ./bin/patterm ./cmd/patterm
+	go build -ldflags "-X main.version=$(VERSION)" -o ./bin/patterm ./cmd/patterm
 
 test: deps
 	go test ./...
diff --git a/cmd/patterm/debug_harness.go b/cmd/patterm/debug_harness.go
index dee275b..768cfd2 100644
--- a/cmd/patterm/debug_harness.go
+++ b/cmd/patterm/debug_harness.go
@@ -2,10 +2,11 @@ package main
 
 import (
 	"encoding/json"
-	"flag"
 	"fmt"
 	"os"
 
+	flag "github.com/spf13/pflag"
+
 	"github.com/hjbdev/patterm/internal/harness"
 )
 
diff --git a/cmd/patterm/main.go b/cmd/patterm/main.go
index e45d141..61c009c 100644
--- a/cmd/patterm/main.go
+++ b/cmd/patterm/main.go
@@ -4,6 +4,7 @@
 //
 //	patterm                      run in $PWD
 //	patterm --project <dir>      run in <dir>
+//	patterm --version            print version and exit
 //	patterm mcp-stdio --socket S --identity I
 //	                             internal: stdio MCP proxy spawned for
 //	                             children, forwards JSON-RPC over S
@@ -13,15 +14,22 @@ package main
 
 import (
 	"context"
-	"flag"
 	"fmt"
 	"os"
+	"runtime/debug"
+	"time"
+
+	flag "github.com/spf13/pflag"
 
 	"github.com/hjbdev/patterm/internal/app"
 	"github.com/hjbdev/patterm/internal/mcp"
 	"github.com/hjbdev/patterm/internal/projectkey"
 )
 
+// version is overridden at build time via `-ldflags "-X main.version=..."`.
+// Defaults to "dev" so source builds are still meaningful.
+var version = "dev"
+
 func main() {
 	// The mcp-stdio subcommand is a separate top-level mode: when an
 	// agent CLI launches `patterm mcp-stdio --socket ...`, the same
@@ -38,9 +46,17 @@ func main() {
 		return
 	}
 
-	var projectDir = flag.String("project", "", "project directory (default $PWD)")
+	var (
+		projectDir  = flag.String("project", "", "project directory (default $PWD)")
+		showVersion = flag.Bool("version", false, "print version and exit")
+	)
 	flag.Parse()
 
+	if *showVersion {
+		fmt.Println(versionString())
+		return
+	}
+
 	cwd, err := os.Getwd()
 	if err != nil {
 		die("getwd: %v", err)
@@ -80,6 +96,33 @@ func runMCPProxy() {
 	}
 }
 
+func versionString() string {
+	commit, date := "unknown", "unknown"
+	if info, ok := debug.ReadBuildInfo(); ok {
+		dirty := false
+		for _, s := range info.Settings {
+			switch s.Key {
+			case "vcs.revision":
+				if len(s.Value) >= 7 {
+					commit = s.Value[:7]
+				} else if s.Value != "" {
+					commit = s.Value
+				}
+			case "vcs.time":
+				if t, err := time.Parse(time.RFC3339, s.Value); err == nil {
+					date = t.Format("2006-01-02")
+				}
+			case "vcs.modified":
+				dirty = s.Value == "true"
+			}
+		}
+		if dirty && commit != "unknown" {
+			commit += "-dirty"
+		}
+	}
+	return fmt.Sprintf("patterm %s (commit %s, built %s)", version, commit, date)
+}
+
 func die(format string, args ...any) {
 	fmt.Fprintf(os.Stderr, "patterm: "+format+"\n", args...)
 	os.Exit(1)
diff --git a/go.mod b/go.mod
index 5e0e902..6a63a7f 100644
--- a/go.mod
+++ b/go.mod
@@ -4,6 +4,7 @@ go 1.26.3
 
 require (
 	github.com/creack/pty v1.1.24
+	github.com/spf13/pflag v1.0.10
 	golang.org/x/term v0.43.0
 )
 
diff --git a/go.sum b/go.sum
index bea4245..9d57516 100644
--- a/go.sum
+++ b/go.sum
@@ -1,5 +1,7 @@
 github.com/creack/pty v1.1.24 h1:bJrF4RRfyJnbTJqzRLHzcGaZK1NeM5kTC9jGgovnR1s=
 github.com/creack/pty v1.1.24/go.mod h1:08sCNb52WyoAwi2QDyzUCTgcvVFhUzewun7wtTfvcwE=
+github.com/spf13/pflag v1.0.10 h1:4EBh2KAYBwaONj6b2Ye1GiHfwjqyROoF4RwYO+vPwFk=
+github.com/spf13/pflag v1.0.10/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 golang.org/x/sys v0.44.0 h1:ildZl3J4uzeKP07r2F++Op7E9B29JRUy+a27EibtBTQ=
 golang.org/x/sys v0.44.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
 golang.org/x/term v0.43.0 h1:S4RLU2sB31O/NCl+zFN9Aru9A/Cq2aqKpTZJ6B+DwT4=