diff --git a/.github/workflows/session-e2e.yaml b/.github/workflows/session-e2e.yaml
new file mode 100644
index 00000000..f6eb4df1
--- /dev/null
+++ b/.github/workflows/session-e2e.yaml
@@ -0,0 +1,78 @@
+name: Session E2E
+
+# Drives the real `lk agent session` start/say/end lifecycle against the minimal
+# one-file echo agent in cmd/lk/testdata/echo-agent, on Linux and Windows. This
+# exercises the detached daemon, the readiness handshake, the console IPC
+# transport, and the model round-trip end to end -- runtime behavior that
+# `go test` alone never covers.
+#
+# Runs on manual dispatch and on pushes to any repo branch (forks can't trigger
+# `push`, so secrets are only exposed to trusted collaborators). It needs live
+# LiveKit credentials -- set these repo secrets first: LIVEKIT_API_KEY,
+# LIVEKIT_API_SECRET, LIVEKIT_URL. The echo agent drives its LLM through LiveKit
+# Inference, so no other provider keys are needed.
+#
+# The echo agent depends on plain PyPI livekit-agents (synced by `uv sync` from
+# its pyproject.toml). Note: on current releases/main, `cli.run_app()` routes
+# `console` through the legacy click CLI, which has no --connect-addr (that
+# lives behind `python -m livekit.agents`). The fixture's __main__ dispatches
+# console mode to the TCP console directly to bridge the daemon's
+# `python <entry> console --connect-addr` launch.
+#
+# Node is intentionally not in the matrix yet: this branch's session daemon only
+# supports Python agents (`detectProject` rejects non-Python), and Node console
+# support depends on the brian/agent-session-node-support CLI line (#868/#878)
+# plus agents-js #1804. Add a node arm once those land.
+
+on:
+  workflow_dispatch:
+  push:
+    branches: ['**']
+
+concurrency:
+  group: session-e2e-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  e2e:
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, windows-latest]
+
+    runs-on: ${{ matrix.os }}
+    name: python on ${{ matrix.os }}
+
+    permissions:
+      contents: read
+
+    steps:
+      - name: Checkout livekit-cli
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+
+      - name: Set up Go
+        uses: actions/setup-go@4a3601121dd01d1626a1e23e37211e3254c1c06c # v6
+        with:
+          go-version-file: go.mod
+          cache: true
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: Set up uv
+        uses: astral-sh/setup-uv@v5
+        with:
+          enable-cache: true
+
+      - name: Sync echo agent deps
+        working-directory: cmd/lk/testdata/echo-agent
+        run: uv sync
+
+      - name: Run session e2e
+        env:
+          LIVEKIT_API_KEY: ${{ secrets.LIVEKIT_API_KEY }}
+          LIVEKIT_API_SECRET: ${{ secrets.LIVEKIT_API_SECRET }}
+          LIVEKIT_URL: ${{ secrets.LIVEKIT_URL }}
+        run: go test ./cmd/lk -run TestSessionE2E -count=1 -v -timeout 600s
diff --git a/.gitignore b/.gitignore
index fa396b82..9901cd1c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -22,3 +22,13 @@ dist/
 
 .DS_Store
 /lk
+
+# local secrets copied for e2e testing
+.env
+
+# python venvs created for e2e agent fixtures
+.venv/
+cmd/lk/testdata/**/.venv
+
+# uv lockfiles for test agent fixtures (resolved fresh in CI)
+cmd/lk/testdata/**/uv.lock
diff --git a/cmd/lk/session.go b/cmd/lk/session.go
index 0b964f1d..4ecb43ee 100644
--- a/cmd/lk/session.go
+++ b/cmd/lk/session.go
@@ -15,7 +15,6 @@
 package main
 
 import (
-	"bufio"
 	"context"
 	"encoding/binary"
 	"encoding/json"
@@ -26,6 +25,7 @@ import (
 	"os/exec"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/urfave/cli/v3"
 )
@@ -38,11 +38,11 @@ const (
 	sessionHost        = "127.0.0.1"
 	defaultSessionPort = 8775
 
-	envSessionPort    = "LK_SESSION_PORT"  // fixed port
-	envSessionDir     = "LK_SESSION_DIR"   // resolved project dir
-	envSessionEntry   = "LK_SESSION_ENTRY" // resolved entrypoint (project-relative)
-	envSessionPType   = "LK_SESSION_PTYPE" // agentfs.ProjectType string
-	envSessionReadyFD = "LK_SESSION_READY_FD"
+	envSessionPort      = "LK_SESSION_PORT"       // fixed port
+	envSessionDir       = "LK_SESSION_DIR"        // resolved project dir
+	envSessionEntry     = "LK_SESSION_ENTRY"      // resolved entrypoint (project-relative)
+	envSessionPType     = "LK_SESSION_PTYPE"      // agentfs.ProjectType string
+	envSessionReadyFile = "LK_SESSION_READY_FILE" // path the daemon writes its status to
 
 	// sessionDaemonSubcommand is the hidden entrypoint `start` re-execs into.
 	sessionDaemonSubcommand = "daemon"
@@ -92,7 +92,7 @@ var agentSessionCommand = &cli.Command{
 			Name:   sessionDaemonSubcommand,
 			Hidden: true,
 			Action: func(ctx context.Context, cmd *cli.Command) error {
-				if os.Getenv(envSessionReadyFD) == "" {
+				if os.Getenv(envSessionReadyFile) == "" {
 					return fmt.Errorf("`session daemon` is an internal entrypoint; run `lk agent session start <entrypoint>` instead")
 				}
 				runSessionDaemon()
@@ -118,19 +118,20 @@ func runSessionStart(ctx context.Context, cmd *cli.Command) error {
 		return fmt.Errorf("could not resolve own binary: %w", err)
 	}
 
-	// Pipe the daemon uses to report readiness (or a startup error) before we
-	// return. This avoids racing a TCP probe against the agent's own connect.
-	readyR, readyW, err := os.Pipe()
+	// Readiness file the daemon writes once it is up (or failed) before we
+	// return, so we don't race a TCP probe against the agent's own connect.
+	readyFile, err := os.CreateTemp("", "lk-session-ready-*.txt")
 	if err != nil {
 		return err
 	}
-	defer readyR.Close()
+	readyPath := readyFile.Name()
+	readyFile.Close()
+	defer os.Remove(readyPath)
 
 	// The daemon is detached, so its own stdout/stderr (panics etc.) go to a
 	// temp log rather than the user's terminal.
 	logFile, err := os.CreateTemp("", "lk-session-daemon-*.log")
 	if err != nil {
-		readyW.Close()
 		return err
 	}
 
@@ -140,24 +141,19 @@ func runSessionStart(ctx context.Context, cmd *cli.Command) error {
 		envSessionDir+"="+projectDir,
 		envSessionEntry+"="+entrypoint,
 		envSessionPType+"="+string(projectType),
-		envSessionReadyFD+"=3", // ExtraFiles[0] is fd 3 in the child
+		envSessionReadyFile+"="+readyPath,
 	)
-	daemon.ExtraFiles = []*os.File{readyW}
 	daemon.Stdout = logFile
 	daemon.Stderr = logFile
 	setDetachedProcAttr(daemon)
 
 	if err := daemon.Start(); err != nil {
-		readyW.Close()
 		logFile.Close()
 		return fmt.Errorf("failed to start session daemon: %w", err)
 	}
-	// Close our copy of the write end so the read below sees EOF if the daemon dies.
-	readyW.Close()
 	logFile.Close()
 
-	status, _ := bufio.NewReader(readyR).ReadString('\n')
-	status = strings.TrimSpace(status)
+	status := awaitDaemonReady(daemon, readyPath)
 	switch {
 	case status == "ready":
 		fmt.Fprintf(os.Stderr, "Detected %s agent (%s in %s)\n", projectType.Lang(), entrypoint, projectDir)
@@ -170,6 +166,43 @@ func runSessionStart(ctx context.Context, cmd *cli.Command) error {
 	}
 }
 
+// awaitDaemonReady waits for the detached daemon to report via the readiness
+// file, returning its status line ("ready" or "error: ...") or "" if the
+// daemon exits or times out without reporting.
+func awaitDaemonReady(daemon *exec.Cmd, readyPath string) string {
+	exited := make(chan struct{})
+	go func() { _ = daemon.Wait(); close(exited) }()
+
+	// Slightly longer than the daemon's own 60s agent-connect timeout so its
+	// "error: timed out ..." status reaches us before we give up.
+	timeout := time.After(65 * time.Second)
+	for {
+		if status, ok := readReadyStatus(readyPath); ok {
+			return status
+		}
+		select {
+		case <-exited:
+			if status, ok := readReadyStatus(readyPath); ok {
+				return status
+			}
+			return ""
+		case <-timeout:
+			return ""
+		case <-time.After(50 * time.Millisecond):
+		}
+	}
+}
+
+// readReadyStatus returns the daemon's status line once the readiness file has
+// content (written atomically via rename), or ok=false while it is still empty.
+func readReadyStatus(path string) (string, bool) {
+	data, err := os.ReadFile(path)
+	if err != nil || len(data) == 0 {
+		return "", false
+	}
+	return strings.TrimSpace(string(data)), true
+}
+
 func runSessionSay(ctx context.Context, cmd *cli.Command) error {
 	text := strings.TrimSpace(strings.Join(cmd.Args().Slice(), " "))
 	if text == "" {
diff --git a/cmd/lk/session_daemon.go b/cmd/lk/session_daemon.go
index 720e8b38..046f2759 100644
--- a/cmd/lk/session_daemon.go
+++ b/cmd/lk/session_daemon.go
@@ -100,26 +100,25 @@ func runSessionDaemon() {
 	agentProc.Kill()
 }
 
-// readyWriter returns the inherited pipe `lk agent session start` reads to learn the
-// daemon became ready (or failed). Nil if not launched via start.
-func readyWriter() *os.File {
-	fdStr := os.Getenv(envSessionReadyFD)
-	if fdStr == "" {
-		return nil
-	}
-	fd, err := strconv.Atoi(fdStr)
-	if err != nil {
-		return nil
-	}
-	return os.NewFile(uintptr(fd), "ready")
+// readyWriter returns the path of the readiness file `lk agent session start`
+// polls to learn the daemon became ready (or failed). Empty if not launched
+// via start.
+func readyWriter() string {
+	return os.Getenv(envSessionReadyFile)
 }
 
-func signalReady(f *os.File, msg string) {
-	if f == nil {
+// signalReady atomically writes the daemon's status to the readiness file the
+// parent `start` is polling. The write-then-rename keeps the parent from
+// reading a partial line.
+func signalReady(path, msg string) {
+	if path == "" {
+		return
+	}
+	tmp := path + ".tmp"
+	if err := os.WriteFile(tmp, []byte(msg+"\n"), 0o600); err != nil {
 		return
 	}
-	fmt.Fprintln(f, msg)
-	f.Close()
+	_ = os.Rename(tmp, path)
 }
 
 type sessionDaemon struct {
diff --git a/cmd/lk/session_e2e_test.go b/cmd/lk/session_e2e_test.go
new file mode 100644
index 00000000..bd46ed25
--- /dev/null
+++ b/cmd/lk/session_e2e_test.go
@@ -0,0 +1,114 @@
+// Copyright 2025 LiveKit, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"context"
+	"net"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+// TestSessionE2E drives the real `lk agent session` lifecycle end to end:
+// build the binary, `start` the detached daemon, `say` to make the model echo
+// a token (asserting the CLI→daemon→agent→LLM round-trip), `end`, then confirm
+// the daemon exited (nothing answers on the port).
+//
+// Opt-in: needs a prepared agent venv + live creds, so it skips unless
+// LIVEKIT_API_KEY is set. Defaults to testdata/echo-agent; override with LK_SESSION_E2E_AGENT.
+func TestSessionE2E(t *testing.T) {
+	if os.Getenv("LIVEKIT_API_KEY") == "" {
+		t.Skip("set LIVEKIT_API_KEY (and prepare the agent venv) to run the session e2e test")
+	}
+	entrypoint := os.Getenv("LK_SESSION_E2E_AGENT")
+	if entrypoint == "" {
+		entrypoint = filepath.Join("testdata", "echo-agent", "agent.py")
+	}
+	entrypoint, err := filepath.Abs(entrypoint)
+	require.NoError(t, err)
+	require.FileExists(t, entrypoint, "agent entrypoint not found (set LK_SESSION_E2E_AGENT to override)")
+
+	// Dedicated port so the test can't collide with a real session on 8775.
+	port := "18775"
+	if p := os.Getenv("LK_SESSION_E2E_PORT"); p != "" {
+		port = p
+	}
+
+	bin := buildLK(t)
+
+	run := func(timeout time.Duration, args ...string) (string, error) {
+		ctx, cancel := context.WithTimeout(context.Background(), timeout)
+		defer cancel()
+		cmd := exec.CommandContext(ctx, bin, args...)
+		cmd.Env = os.Environ()
+		out, err := cmd.CombinedOutput()
+		return string(out), err
+	}
+
+	// Best-effort teardown so a mid-run failure doesn't leave the daemon alive.
+	t.Cleanup(func() {
+		_, _ = run(15*time.Second, "agent", "session", "end", "--port", port)
+	})
+
+	// start: launches the detached daemon and returns once the agent is ready.
+	startOut, err := run(90*time.Second, "agent", "session", "start", "--port", port, entrypoint)
+	require.NoError(t, err, "session start failed:\n%s", startOut)
+	require.Contains(t, startOut, "Session started.", "start did not report readiness:\n%s", startOut)
+
+	// say: the token appears once in the echoed prompt and again in the reply, so
+	// >=2 occurrences proves the agent answered, not just the local echo.
+	token := "PINEAPPLE7351"
+	sayOut, err := run(90*time.Second, "agent", "session", "say", "--port", port,
+		"Repeat this token back to me exactly and nothing else: "+token)
+	require.NoError(t, err, "session say failed:\n%s", sayOut)
+	require.GreaterOrEqualf(t, strings.Count(sayOut, token), 2,
+		"agent did not echo the token back; say output:\n%s", sayOut)
+
+	endOut, err := run(30*time.Second, "agent", "session", "end", "--port", port)
+	require.NoError(t, err, "session end failed:\n%s", endOut)
+	require.Contains(t, endOut, "Session ended.", "end did not confirm shutdown:\n%s", endOut)
+
+	// The detached daemon should now be gone: nothing should answer on the port.
+	require.Eventually(t, func() bool {
+		conn, derr := net.DialTimeout("tcp", "127.0.0.1:"+port, 200*time.Millisecond)
+		if derr != nil {
+			return true // refused → daemon exited
+		}
+		conn.Close()
+		return false
+	}, 10*time.Second, 200*time.Millisecond, "session daemon still listening on port %s after end", port)
+}
+
+// buildLK compiles the lk binary into a temp dir and returns its path.
+func buildLK(t *testing.T) string {
+	t.Helper()
+	bin := filepath.Join(t.TempDir(), "lk")
+	if runtime.GOOS == "windows" {
+		bin += ".exe"
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), 120*time.Second)
+	defer cancel()
+	build := exec.CommandContext(ctx, "go", "build", "-o", bin, ".")
+	out, err := build.CombinedOutput()
+	require.NoErrorf(t, err, "failed to build lk binary:\n%s", out)
+	return bin
+}
diff --git a/cmd/lk/testdata/echo-agent/agent.py b/cmd/lk/testdata/echo-agent/agent.py
new file mode 100644
index 00000000..ed9ea971
--- /dev/null
+++ b/cmd/lk/testdata/echo-agent/agent.py
@@ -0,0 +1,48 @@
+"""Minimal one-file echo agent for the `lk agent session` e2e test.
+
+Driven in text mode, so an LLM is the only component needed. Echoes the user's
+text verbatim, which the test asserts on.
+"""
+
+from dotenv import load_dotenv
+from livekit.agents import Agent, AgentServer, AgentSession, JobContext, cli, inference
+
+load_dotenv()
+
+server = AgentServer()
+
+
+@server.rtc_session()
+async def entrypoint(ctx: JobContext):
+    session = AgentSession(llm=inference.LLM(model="openai/gpt-4o-mini"))
+    await session.start(
+        agent=Agent(
+            instructions=(
+                "You are an echo bot. Reply with exactly the text the user "
+                "sends, verbatim, and nothing else."
+            ),
+        ),
+        room=ctx.room,
+    )
+    # No TTS, so disable audio output or the turn crashes in tts_node.
+    session.output.set_audio_enabled(False)
+    await ctx.connect()
+
+
+if __name__ == "__main__":
+    import sys
+
+    argv = sys.argv[1:]
+    if argv and argv[0] == "console":
+        # The daemon launches `python agent.py console --connect-addr <addr>`, but
+        # cli.run_app() sends `console` to the legacy click CLI (no --connect-addr),
+        # so dispatch to the TCP console directly.
+        from livekit.agents.cli.cli import _run_tcp_console
+
+        _run_tcp_console(
+            server=server,
+            connect_addr=argv[argv.index("--connect-addr") + 1],
+            record="--record" in argv,
+        )
+    else:
+        cli.run_app(server)
diff --git a/cmd/lk/testdata/echo-agent/pyproject.toml b/cmd/lk/testdata/echo-agent/pyproject.toml
new file mode 100644
index 00000000..a0f07ffa
--- /dev/null
+++ b/cmd/lk/testdata/echo-agent/pyproject.toml
@@ -0,0 +1,10 @@
+# uv project marker: [tool.uv] lets the daemon's `uv run python` auto-sync
+# these deps -- no separate install step.
+[project]
+name = "lk-session-e2e-echo-agent"
+version = "0"
+requires-python = ">=3.12"
+dependencies = ["livekit-agents", "python-dotenv"]
+
+[tool.uv]
+package = false