diff --git a/build.zig b/build.zig
index 8bc6245..4118fe3 100644
--- a/build.zig
+++ b/build.zig
@@ -96,6 +96,11 @@ pub fn build(b: *std.Build) void {
     const smoke_cmd = b.addRunArtifact(smoke_tests);
     const smoke_step = b.step("v1-smoke", "Run cheap v1 end-to-end fixture suite");
     smoke_step.dependOn(&smoke_cmd.step);
+
+    const terminal_e2e_cmd = b.addSystemCommand(&.{ "python3", "tools/terminal_e2e.py" });
+    terminal_e2e_cmd.addArtifactArg(exe);
+    const terminal_e2e_step = b.step("terminal-e2e", "Run PTY-backed browser-terminal E2E checks");
+    terminal_e2e_step.dependOn(&terminal_e2e_cmd.step);
 }
 
 fn addRunProfileStep(b: *std.Build, profile: Profile, exe: *std.Build.Step.Compile) void {
diff --git a/tools/terminal_e2e.py b/tools/terminal_e2e.py
new file mode 100755
index 0000000..092a82c
--- /dev/null
+++ b/tools/terminal_e2e.py
@@ -0,0 +1,266 @@
+#!/usr/bin/env python3
+"""PTY-backed terminal E2E harness for mim.
+
+Runs a tiny high-signal scenario through a real pseudo-terminal and writes
+browser-viewable terminal artifacts. No third-party dependencies.
+"""
+from __future__ import annotations
+
+import argparse
+import html
+import os
+import pty
+import select
+import signal
+import shutil
+import sys
+import tempfile
+import time
+from pathlib import Path
+
+ESC = 0x1B
+
+
+def visible_controls(data: bytes) -> str:
+    out: list[str] = []
+    text = data.decode("utf-8", errors="replace")
+    for ch in text:
+        code = ord(ch)
+        if ch == "\r":
+            out.append("␍")
+        elif ch == "\n":
+            out.append("␊\n")
+        elif ch == "\x1b":
+            out.append("␛")
+        elif ch == "\t":
+            out.append("⇥")
+        elif code < 0x20:
+            out.append("␀")
+        else:
+            out.append(ch)
+    return "".join(out)
+
+
+class TerminalGrid:
+    def __init__(self, width: int, height: int) -> None:
+        self.width = width
+        self.height = height
+        self.rows = [[" " for _ in range(width)] for _ in range(height)]
+        self.row = 0
+        self.col = 0
+
+    def clear(self) -> None:
+        self.rows = [[" " for _ in range(self.width)] for _ in range(self.height)]
+        self.row = 0
+        self.col = 0
+
+    def newline(self) -> None:
+        self.row += 1
+        if self.row >= self.height:
+            self.rows.pop(0)
+            self.rows.append([" " for _ in range(self.width)])
+            self.row = self.height - 1
+
+    def put_char(self, ch: str) -> None:
+        if ch == "\r":
+            self.col = 0
+            return
+        if ch == "\n":
+            self.newline()
+            return
+        if self.col >= self.width:
+            self.col = 0
+            self.newline()
+        if 0 <= self.row < self.height and 0 <= self.col < self.width:
+            self.rows[self.row][self.col] = ch
+        self.col += 1
+
+    def feed(self, data: bytes) -> None:
+        i = 0
+        text = data.decode("utf-8", errors="replace")
+        while i < len(text):
+            ch = text[i]
+            if ch == "\x1b" and i + 1 < len(text) and text[i + 1] == "[":
+                j = i + 2
+                while j < len(text) and not ("@" <= text[j] <= "~"):
+                    j += 1
+                if j >= len(text):
+                    break
+                command = text[j]
+                params = text[i + 2 : j]
+                if command == "H":
+                    self.row = 0
+                    self.col = 0
+                elif command == "J" and params.endswith("2"):
+                    self.clear()
+                # SGR and unknown CSI are intentionally ignored for semantic grid.
+                i = j + 1
+                continue
+            self.put_char(ch)
+            i += 1
+
+    def lines(self) -> list[str]:
+        return ["".join(row).rstrip() for row in self.rows]
+
+
+def read_available(fd: int, timeout: float = 0.12) -> bytes:
+    chunks: list[bytes] = []
+    deadline = time.monotonic() + timeout
+    while True:
+        remaining = max(0.0, deadline - time.monotonic())
+        ready, _, _ = select.select([fd], [], [], remaining)
+        if not ready:
+            break
+        try:
+            chunk = os.read(fd, 65536)
+        except OSError:
+            break
+        if not chunk:
+            break
+        chunks.append(chunk)
+        deadline = time.monotonic() + 0.04
+    return b"".join(chunks)
+
+
+def spawn_under_pty(argv: list[str], width: int, height: int) -> tuple[int, int]:
+    pid, fd = pty.fork()
+    if pid == 0:
+        os.environ["TERM"] = "xterm-256color"
+        try:
+            import fcntl
+            import struct
+            import termios
+
+            winsize = struct.pack("HHHH", height, width, 0, 0)
+            fcntl.ioctl(0, termios.TIOCSWINSZ, winsize)
+        except Exception:
+            pass
+        os.execv(argv[0], argv)
+    return pid, fd
+
+
+def svg_for_lines(lines: list[str], width: int, height: int) -> str:
+    cell_w = 9
+    cell_h = 18
+    pad = 12
+    svg_w = pad * 2 + width * cell_w
+    svg_h = pad * 2 + height * cell_h
+    body = []
+    for idx, line in enumerate(lines[:height]):
+        body.append(
+            f'<text x="{pad}" y="{pad + (idx + 1) * cell_h}" xml:space="preserve">{html.escape(line)}</text>'
+        )
+    return "\n".join(
+        [
+            f'<svg xmlns="http://www.w3.org/2000/svg" width="{svg_w}" height="{svg_h}" viewBox="0 0 {svg_w} {svg_h}">',
+            '<rect width="100%" height="100%" fill="#12161e"/>',
+            '<style>text{font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;font-size:14px;fill:#d6deeb}</style>',
+            *body,
+            "</svg>",
+        ]
+    )
+
+
+def html_for_lines(lines: list[str], raw_svg_name: str) -> str:
+    escaped = html.escape("\n".join(lines))
+    return f"""<!doctype html>
+<meta charset="utf-8">
+<title>mim terminal-e2e</title>
+<style>
+body {{ margin: 0; background: #0f131a; color: #d6deeb; }}
+.terminal {{ white-space: pre; font: 14px/18px ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; padding: 12px; }}
+a {{ color: #7ee787; }}
+</style>
+<div class="terminal">{escaped}</div>
+<p><a href="{html.escape(raw_svg_name)}">SVG screenshot artifact</a></p>
+"""
+
+
+def run_scenario(mim: Path, out_dir: Path, width: int, height: int) -> None:
+    if out_dir.exists():
+        shutil.rmtree(out_dir)
+    out_dir.mkdir(parents=True, exist_ok=True)
+    with tempfile.TemporaryDirectory(prefix="mim-terminal-e2e-") as tmp:
+        target = Path(tmp) / "note.txt"
+        target.write_text("", encoding="utf-8")
+        pid, fd = spawn_under_pty([str(mim), str(target)], width, height)
+        transcript = bytearray()
+        grid = TerminalGrid(width, height)
+        try:
+            for payload in [b"", b"w", b"h", b"a", b"t", b" ", b"i", b"s", b" ", b"u", b"p", b" ", b"n", b" ", b"w", b" ", b"q"]:
+                if payload:
+                    os.write(fd, payload)
+                chunk = read_available(fd)
+                transcript.extend(chunk)
+                grid.feed(chunk)
+            deadline = time.monotonic() + 2.0
+            while time.monotonic() < deadline:
+                done_pid, status = os.waitpid(pid, os.WNOHANG)
+                chunk = read_available(fd, 0.03)
+                transcript.extend(chunk)
+                grid.feed(chunk)
+                if done_pid == pid:
+                    if status != 0:
+                        raise SystemExit(f"mim exited non-zero: status={status}")
+                    break
+            else:
+                (out_dir).mkdir(parents=True, exist_ok=True)
+                (out_dir / "raw-timeout.bin").write_bytes(bytes(transcript))
+                (out_dir / "visible-timeout.txt").write_text(visible_controls(bytes(transcript)), encoding="utf-8")
+                (out_dir / "transcript-timeout.txt").write_text("\n".join(grid.lines()) + "\n", encoding="utf-8")
+                os.kill(pid, signal.SIGTERM)
+                raise SystemExit(f"mim did not exit after save+quit script; artifacts={out_dir}")
+        finally:
+            try:
+                os.close(fd)
+            except OSError:
+                pass
+
+        saved = target.read_text(encoding="utf-8")
+        lines = grid.lines()
+        (out_dir / "raw.bin").write_bytes(bytes(transcript))
+        (out_dir / "visible-controls.txt").write_text(visible_controls(bytes(transcript)), encoding="utf-8")
+        (out_dir / "transcript.txt").write_text("\n".join(lines) + "\n", encoding="utf-8")
+        (out_dir / "screenshot.svg").write_text(svg_for_lines(lines, width, height), encoding="utf-8")
+        (out_dir / "terminal.html").write_text(html_for_lines(lines, "screenshot.svg"), encoding="utf-8")
+
+        failures: list[str] = []
+        if saved != "what is up":
+            failures.append(f"saved file mismatch: {saved!r}")
+        joined = "\n".join(lines)
+        raw_text = bytes(transcript).decode("utf-8", errors="ignore")
+        if "1│" not in raw_text:
+            failures.append("line-number gutter missing from terminal output")
+        if "▌" not in raw_text:
+            failures.append("cursor marker missing from terminal output")
+        if "mode:normal" not in raw_text and "saved" not in raw_text:
+            failures.append("expected editor status not observed")
+        if "^[" in raw_text:
+            failures.append("escape appears echoed as ^[")
+        if "mode:normal" not in raw_text:
+            failures.append("Space-n did not leave insert mode before save/quit")
+        if any(len(line) > width for line in lines):
+            failures.append("terminal line exceeds viewport width")
+        if failures:
+            print(f"artifacts\t{out_dir}", file=sys.stderr)
+            for failure in failures:
+                print(f"FAIL\t{failure}", file=sys.stderr)
+            raise SystemExit(1)
+
+    print("scenario\tstatus\tartifacts")
+    print(f"raw-key-chrome-crlf\tPASS\t{out_dir}")
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description="Run mim through a PTY and write browser-viewable terminal E2E artifacts.")
+    parser.add_argument("mim", type=Path, help="path to compiled mim binary")
+    parser.add_argument("--out", type=Path, default=Path(".zig-cache/terminal-e2e/raw-key-chrome-crlf"))
+    parser.add_argument("--width", type=int, default=48)
+    parser.add_argument("--height", type=int, default=16)
+    args = parser.parse_args()
+    run_scenario(args.mim.resolve(), args.out, args.width, args.height)
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())