diff --git a/crates/claude-chill/src/color_preservation_tests.rs b/crates/claude-chill/src/color_preservation_tests.rs
new file mode 100644
index 0000000..6fed42a
--- /dev/null
+++ b/crates/claude-chill/src/color_preservation_tests.rs
@@ -0,0 +1,216 @@
+//! Color / SGR / hyperlink preservation tests.
+//!
+//! These tests feed modern terminal styling bytes through a real `Proxy`,
+//! force a render, capture what the proxy emits to its stdout side, and
+//! assert that the styling survives the round-trip.
+//!
+//! They currently FAIL on master because the underlying `vt100 0.16`
+//! emulator only models a handful of attributes (fg/bg color, bold, dim,
+//! italic, underline, inverse). Anything else — OSC 8 hyperlinks,
+//! strikethrough, fancy underline styles, underline color — is silently
+//! dropped on render.
+//!
+//! They are gated behind `#[ignore]` so CI stays green. Run them with:
+//!     cargo test -p claude-chill --lib color_preservation -- --ignored
+//!
+//! The expectation is that they pass once the emulator is swapped to
+//! termwiz's `Surface`. Remove the `#[ignore]` attributes at that point.
+
+#[cfg(test)]
+mod tests {
+    use crate::proxy::{Proxy, ProxyConfig};
+    use nix::fcntl::{FcntlArg, OFlag, fcntl};
+    use nix::pty::openpty;
+    use nix::sys::termios::{self, SetArg};
+    use nix::unistd::{pipe, read};
+    use std::os::fd::{AsFd, AsRawFd, OwnedFd};
+    use std::os::unix::process::CommandExt;
+    use std::process::{Child, Command};
+
+    fn pty_mock_binary() -> Option<String> {
+        let manifest_dir = env!("CARGO_MANIFEST_DIR");
+        let bin = format!("{}/../../target/debug/pty-mock", manifest_dir);
+        if std::path::Path::new(&bin).exists() {
+            Some(bin)
+        } else {
+            None
+        }
+    }
+
+    fn spawn_echo_child() -> Option<(OwnedFd, Child)> {
+        let bin = pty_mock_binary()?;
+        let pty = openpty(None, None).expect("openpty failed");
+
+        let slave_fd = pty.slave.as_raw_fd();
+        let mut termios_settings = termios::tcgetattr(&pty.slave).expect("tcgetattr failed");
+        termios::cfmakeraw(&mut termios_settings);
+        termios::tcsetattr(&pty.slave, SetArg::TCSANOW, &termios_settings)
+            .expect("tcsetattr failed");
+
+        let child = unsafe {
+            Command::new(&bin)
+                .arg("echo")
+                .stdin(pty.slave.try_clone().expect("clone slave"))
+                .stdout(pty.slave.try_clone().expect("clone slave"))
+                .stderr(pty.slave.try_clone().expect("clone slave"))
+                .pre_exec(move || {
+                    if libc::setsid() == -1 {
+                        return Err(std::io::Error::last_os_error());
+                    }
+                    if libc::ioctl(slave_fd, libc::TIOCSCTTY as libc::c_ulong, 0) == -1 {
+                        return Err(std::io::Error::last_os_error());
+                    }
+                    Ok(())
+                })
+                .spawn()
+                .expect("failed to spawn pty-mock echo")
+        };
+
+        drop(pty.slave);
+
+        let flags = fcntl(&pty.master, FcntlArg::F_GETFL).expect("F_GETFL");
+        let flags = OFlag::from_bits_truncate(flags);
+        fcntl(&pty.master, FcntlArg::F_SETFL(flags | OFlag::O_NONBLOCK)).expect("F_SETFL");
+
+        Some((pty.master, child))
+    }
+
+    fn make_proxy(master: OwnedFd, child: Child) -> Proxy {
+        Proxy::new_for_test(master, child, ProxyConfig::default(), 24, 80)
+    }
+
+    /// Make a non-blocking pipe to capture proxy output.
+    fn capture_pipe() -> (OwnedFd, OwnedFd) {
+        let (rx, tx) = pipe().expect("pipe failed");
+        let flags = fcntl(&rx, FcntlArg::F_GETFL).expect("F_GETFL");
+        let flags = OFlag::from_bits_truncate(flags);
+        fcntl(&rx, FcntlArg::F_SETFL(flags | OFlag::O_NONBLOCK)).expect("F_SETFL");
+        (rx, tx)
+    }
+
+    fn drain(rx: &OwnedFd) -> Vec<u8> {
+        let mut buf = [0u8; 65536];
+        let mut out = Vec::new();
+        loop {
+            match read(rx.as_fd(), &mut buf) {
+                Ok(0) => break,
+                Ok(n) => out.extend_from_slice(&buf[..n]),
+                Err(_) => break,
+            }
+        }
+        out
+    }
+
+    /// Feed `input` through the proxy, force a render to a captured pipe,
+    /// and return what the proxy emitted.
+    fn render_and_capture(input: &[u8]) -> Option<Vec<u8>> {
+        let (master, child) = spawn_echo_child()?;
+        let mut proxy = make_proxy(master, child);
+        let (rx, tx) = capture_pipe();
+
+        proxy.process_output(input, &tx).expect("process_output");
+        proxy.force_render(&tx).expect("force_render");
+
+        Some(drain(&rx))
+    }
+
+    fn contains_bytes(haystack: &[u8], needle: &[u8]) -> bool {
+        haystack.windows(needle.len()).any(|w| w == needle)
+    }
+
+    #[test]
+    #[ignore] // FIXME: passes once VT emulator swap to termwiz lands
+    fn osc8_hyperlink_survives_render() {
+        // OSC 8 hyperlinks — used for clickable file paths / URLs.
+        // Format: ESC ] 8 ; ; URL ESC \ ... ESC ] 8 ; ; ESC \
+        let mut input = Vec::new();
+        input.extend_from_slice(b"\x1b]8;;https://example.com/foo\x1b\\");
+        input.extend_from_slice(b"link text");
+        input.extend_from_slice(b"\x1b]8;;\x1b\\");
+
+        let captured = render_and_capture(&input).expect("pty-mock binary missing");
+        assert!(
+            contains_bytes(&captured, b"\x1b]8;;https://example.com/foo"),
+            "OSC 8 hyperlink open should survive render, got: {:?}",
+            String::from_utf8_lossy(&captured)
+        );
+        assert!(
+            contains_bytes(&captured, b"\x1b]8;;\x1b\\"),
+            "OSC 8 hyperlink close should survive render, got: {:?}",
+            String::from_utf8_lossy(&captured)
+        );
+    }
+
+    #[test]
+    #[ignore] // FIXME: passes once VT emulator swap to termwiz lands
+    fn strikethrough_survives_render() {
+        // SGR 9 = strikethrough. vt100 0.16 has no field for it.
+        let input = b"\x1b[9mstruck through text\x1b[0m";
+        let captured = render_and_capture(input).expect("pty-mock binary missing");
+        assert!(
+            contains_bytes(&captured, b"\x1b[9m") || contains_bytes(&captured, b";9m"),
+            "SGR 9 strikethrough should survive render, got: {:?}",
+            String::from_utf8_lossy(&captured)
+        );
+    }
+
+    #[test]
+    #[ignore] // FIXME: passes once VT emulator swap to termwiz lands
+    fn curly_underline_survives_render() {
+        // SGR 4:3 = curly underline (kitty/wezterm/ghostty all support).
+        let input = b"\x1b[4:3mcurly underline\x1b[0m";
+        let captured = render_and_capture(input).expect("pty-mock binary missing");
+        assert!(
+            contains_bytes(&captured, b"4:3"),
+            "SGR 4:3 curly underline should survive render, got: {:?}",
+            String::from_utf8_lossy(&captured)
+        );
+    }
+
+    #[test]
+    #[ignore] // FIXME: passes once VT emulator swap to termwiz lands
+    fn underline_color_survives_render() {
+        // SGR 58:2::R:G:B = truecolor underline color.
+        let input = b"\x1b[4m\x1b[58:2::255:0:0mcolored underline\x1b[0m";
+        let captured = render_and_capture(input).expect("pty-mock binary missing");
+        assert!(
+            contains_bytes(&captured, b"58:2") || contains_bytes(&captured, b"58;2"),
+            "SGR 58 underline color should survive render, got: {:?}",
+            String::from_utf8_lossy(&captured)
+        );
+    }
+
+    #[test]
+    #[ignore] // FIXME: passes once VT emulator swap to termwiz lands
+    fn double_underline_survives_render() {
+        // SGR 21 = doubly underlined.
+        let input = b"\x1b[21mdouble underlined\x1b[0m";
+        let captured = render_and_capture(input).expect("pty-mock binary missing");
+        assert!(
+            contains_bytes(&captured, b"\x1b[21m")
+                || contains_bytes(&captured, b";21m")
+                || contains_bytes(&captured, b"4:2"),
+            "SGR 21 double underline should survive render, got: {:?}",
+            String::from_utf8_lossy(&captured)
+        );
+    }
+
+    /// Sanity check: confirm a styling attribute that vt100 *does* support
+    /// already survives the render. If this ever fails, something more
+    /// fundamental is broken than just attribute coverage.
+    #[test]
+    fn truecolor_foreground_survives_render() {
+        // SGR 38;2;R;G;B = truecolor foreground. vt100 supports this.
+        let input = b"\x1b[38;2;255;128;0morange text\x1b[0m";
+        let Some(captured) = render_and_capture(input) else {
+            // pty-mock not built — skip.
+            return;
+        };
+        assert!(
+            contains_bytes(&captured, b"38;2;255;128;0")
+                || contains_bytes(&captured, b"38:2::255:128:0"),
+            "truecolor foreground should survive render (sanity), got: {:?}",
+            String::from_utf8_lossy(&captured)
+        );
+    }
+}
diff --git a/crates/claude-chill/src/lib.rs b/crates/claude-chill/src/lib.rs
index 1219fef..3fc02d7 100644
--- a/crates/claude-chill/src/lib.rs
+++ b/crates/claude-chill/src/lib.rs
@@ -1,3 +1,5 @@
+#[cfg(test)]
+mod color_preservation_tests;
 pub mod config;
 pub mod escape_filter;
 pub mod escape_sequences;
diff --git a/crates/claude-chill/src/proxy.rs b/crates/claude-chill/src/proxy.rs
index 071c15b..a4a29d7 100644
--- a/crates/claude-chill/src/proxy.rs
+++ b/crates/claude-chill/src/proxy.rs
@@ -412,6 +412,11 @@ impl Proxy {
         self.pty_master.as_raw_fd()
     }
 
+    #[cfg(test)]
+    pub(crate) fn force_render<F: AsFd>(&mut self, stdout_fd: &F) -> Result<()> {
+        self.render_vt_screen(stdout_fd)
+    }
+
     #[cfg(test)]
     pub(crate) fn flush_drain_buffer<F: AsFd>(&mut self, stdout_fd: &F) -> Result<()> {
         if !self.pty_drain_buffer.is_empty() {