diff --git a/crates/etherpad-client/tests/fixtures/wire-vectors.json b/crates/etherpad-client/tests/fixtures/wire-vectors.json
new file mode 100644
index 0000000..6b8ff01
--- /dev/null
+++ b/crates/etherpad-client/tests/fixtures/wire-vectors.json
@@ -0,0 +1,7 @@
+[
+  {"name":"plain-insert","initialText":"abc\n","changeset":"Z:4>3=3+3$XYZ","pool":{"numToAttrib":{},"nextNum":0},"resultText":"abcXYZ\n"},
+  {"name":"plain-delete","initialText":"abcdef\n","changeset":"Z:7<3=1-3$","pool":{"numToAttrib":{},"nextNum":0},"resultText":"aef\n"},
+  {"name":"formatted-insert","initialText":"abc\n","changeset":"Z:4>4=3*0+4$bold","pool":{"numToAttrib":{"0":["bold","true"]},"nextNum":1},"resultText":"abcbold\n"},
+  {"name":"multiline-insert","initialText":"abc\n","changeset":"Z:4>8=3|2+8$one\ntwo\n","pool":{"numToAttrib":{},"nextNum":0},"resultText":"abcone\ntwo\n\n"},
+  {"name":"attrib-reuse","initialText":"abc\n","changeset":"Z:4>2*0+1=3*0+1$AB","pool":{"numToAttrib":{"0":["bold","true"]},"nextNum":1},"resultText":"AabcB\n"}
+]
diff --git a/crates/etherpad-client/tests/smoke.rs b/crates/etherpad-client/tests/smoke.rs
new file mode 100644
index 0000000..86b2b99
--- /dev/null
+++ b/crates/etherpad-client/tests/smoke.rs
@@ -0,0 +1,204 @@
+//! Live wire-compat smoke test (Phase 2 of ether/etherpad#7923).
+//!
+//! Connects a `PadSession` to a fresh pad on a running Etherpad, sends a
+//! changeset that inserts a known marker, then verifies the text round-tripped
+//! — preferring the HTTP `getText` API (needs an apikey) and falling back to a
+//! fresh `PadSession`'s `initial_text`.
+//!
+//! Marked `#[ignore]` so plain `cargo test` skips it; the manifest command
+//! `cargo test --test smoke -- --ignored` runs it. Modeled on the skip pattern
+//! in `integration_etherpad.rs`, but broadened: not only an unreachable base
+//! URL but also any failing Etherpad-specific setup step (cookie fetch, WS
+//! connect, handshake) prints a skip message and returns rather than failing.
+//! This keeps the test safe to run against environments with no Etherpad — or
+//! with something else answering on the port.
+//!
+//! Env contract:
+//!   ETHERPAD_SMOKE_URL    base URL (fallback PAD_ETHERPAD_BASE, then
+//!                         http://localhost:9003)
+//!   ETHERPAD_SMOKE_APIKEY apikey for the HTTP API getText verification path
+
+use etherpad_client::Socket;
+use etherpad_client::changeset::{Changeset, Op, OpCode};
+use etherpad_client::session::{PadSession, SessionConfig};
+use etherpad_client::socket::TungsteniteSocket;
+use std::time::Duration;
+
+fn smoke_base() -> String {
+    std::env::var("ETHERPAD_SMOKE_URL")
+        .or_else(|_| std::env::var("PAD_ETHERPAD_BASE"))
+        .unwrap_or_else(|_| "http://localhost:9003".to_string())
+}
+
+async fn reachable(base: &str) -> bool {
+    let Ok(c) = reqwest::Client::builder()
+        .timeout(Duration::from_secs(5))
+        .build()
+    else {
+        return false;
+    };
+    c.get(base).send().await.is_ok()
+}
+
+/// Canonical insert at position `pos` of `text` into `old_text`. Mirrors the
+/// builder used by `integration_roundtrip.rs` (trailing keep is implicit).
+fn insert_changeset(old_text: &str, pos: u32, text: &str) -> Changeset {
+    let old_len = old_text.chars().count() as u32;
+    let inserted = text.chars().count() as u32;
+    let mut ops = Vec::new();
+    if pos > 0 {
+        let lines = old_text
+            .chars()
+            .take(pos as usize)
+            .filter(|c| *c == '\n')
+            .count() as u32;
+        ops.push(Op {
+            opcode: OpCode::Keep,
+            chars: pos,
+            lines,
+            attribs: vec![],
+        });
+    }
+    ops.push(Op {
+        opcode: OpCode::Insert,
+        chars: inserted,
+        lines: text.matches('\n').count() as u32,
+        attribs: vec![],
+    });
+    Changeset {
+        old_len,
+        net_delta: inserted as i64,
+        ops,
+        char_bank: text.to_string(),
+    }
+}
+
+/// Read pad text back via the HTTP API. Returns `Ok(None)` if no apikey is set.
+async fn get_text_via_api(base: &str, pad_id: &str) -> Result<Option<String>, String> {
+    let Ok(apikey) = std::env::var("ETHERPAD_SMOKE_APIKEY") else {
+        return Ok(None);
+    };
+    if apikey.is_empty() {
+        return Ok(None);
+    }
+    let url = format!("{}/api/1.2.13/getText", base.trim_end_matches('/'));
+    let c = reqwest::Client::builder()
+        .timeout(Duration::from_secs(10))
+        .build()
+        .map_err(|e| e.to_string())?;
+    let resp = c
+        .get(&url)
+        .query(&[("apikey", apikey.as_str()), ("padID", pad_id)])
+        .send()
+        .await
+        .map_err(|e| e.to_string())?;
+    let body: serde_json::Value = resp.json().await.map_err(|e| e.to_string())?;
+    // { code, message, data: { text } }
+    let text = body["data"]["text"].as_str().map(|s| s.to_string());
+    Ok(text)
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+#[ignore = "requires a running Etherpad; run with --ignored"]
+async fn smoke_wire_roundtrip() {
+    let base = smoke_base();
+    if !reachable(&base).await {
+        eprintln!("Etherpad not reachable at {base}, skipping smoke test");
+        return;
+    }
+    // UUID rather than epoch seconds so concurrent runs never collide.
+    let pad_id = format!("pad-rust-smoke-{}", uuid::Uuid::now_v7());
+    eprintln!("target: {base}/p/{pad_id}");
+
+    // The HTTP probe above only proves *something* answers at `base`. The
+    // Etherpad-specific setup (cookie fetch, WS connect, handshake) is also
+    // treated as a skip condition so a reachable-but-not-Etherpad endpoint
+    // skips cleanly instead of hard-failing the test.
+    let cookie = match TungsteniteSocket::fetch_pad_cookie(&base, &pad_id).await {
+        Ok(c) => c,
+        Err(e) => {
+            eprintln!("fetch_pad_cookie failed ({e}); not a usable Etherpad, skipping");
+            return;
+        }
+    };
+    let mut socket = TungsteniteSocket::new(&base, Some(cookie));
+    if let Err(e) = socket.connect().await {
+        eprintln!("ws connect failed ({e}); not a usable Etherpad, skipping");
+        return;
+    }
+    let mut session = PadSession::new(
+        Box::new(socket),
+        SessionConfig {
+            pad_id: pad_id.clone(),
+            token: "t.smoke".into(),
+            protocol_version: 2,
+        },
+    );
+    if let Err(e) = session.handshake().await {
+        eprintln!("handshake failed ({e}); not a usable Etherpad, skipping");
+        return;
+    }
+
+    let initial_text = session.initial_text().to_string();
+    let initial_len = initial_text.chars().count() as u32;
+    let marker = format!("RUST-SMOKE-{}\n", uuid::Uuid::now_v7());
+    let cs = insert_changeset(&initial_text, initial_len, &marker);
+    session.send_changeset(&cs).await.expect("send_changeset");
+
+    // Pump briefly so the server processes the commit.
+    let deadline = tokio::time::Instant::now() + Duration::from_secs(5);
+    while tokio::time::Instant::now() < deadline {
+        let remaining = deadline.duration_since(tokio::time::Instant::now());
+        match tokio::time::timeout(remaining, session.pump_once_event()).await {
+            Ok(Ok(_)) => {}
+            Ok(Err(e)) => {
+                eprintln!("pump error: {e}");
+                break;
+            }
+            Err(_) => break,
+        }
+    }
+    session.disconnect().await.ok();
+
+    let needle = marker.trim_end();
+
+    // Verification path 1: HTTP API getText (preferred, if apikey provided).
+    match get_text_via_api(&base, &pad_id).await {
+        Ok(Some(text)) => {
+            assert!(
+                text.contains(needle),
+                "marker {:?} not found in getText response {:?}",
+                marker,
+                text
+            );
+            eprintln!("verified via HTTP getText");
+            return;
+        }
+        Ok(None) => eprintln!("ETHERPAD_SMOKE_APIKEY unset; verifying via fresh session"),
+        Err(e) => eprintln!("getText failed ({e}); verifying via fresh session"),
+    }
+
+    // Verification path 2: fresh session reads the pad's persisted text.
+    let cookie_b = TungsteniteSocket::fetch_pad_cookie(&base, &pad_id)
+        .await
+        .expect("fetch_pad_cookie B");
+    let mut sock_b = TungsteniteSocket::new(&base, Some(cookie_b));
+    sock_b.connect().await.expect("ws connect B");
+    let mut sess_b = PadSession::new(
+        Box::new(sock_b),
+        SessionConfig {
+            pad_id: pad_id.clone(),
+            token: "t.smoke-B".into(),
+            protocol_version: 2,
+        },
+    );
+    sess_b.handshake().await.expect("handshake B");
+    assert!(
+        sess_b.initial_text().contains(needle),
+        "marker {:?} not found in fresh session initial text {:?}",
+        marker,
+        sess_b.initial_text()
+    );
+    eprintln!("verified via fresh session initial_text");
+    sess_b.disconnect().await.ok();
+}
diff --git a/crates/etherpad-client/tests/vectors.rs b/crates/etherpad-client/tests/vectors.rs
new file mode 100644
index 0000000..ec4c5b6
--- /dev/null
+++ b/crates/etherpad-client/tests/vectors.rs
@@ -0,0 +1,96 @@
+//! Downstream wire-compatibility vectors (Phase 2 of ether/etherpad#7923).
+//!
+//! Etherpad core ships a canonical wire-format fixture that every client must
+//! decode identically. This test loads that fixture and, for each vector,
+//! applies `changeset` to `initialText` using the crate's OWN changeset
+//! parser + OT apply path (the same code exercised by `changeset_roundtrip.rs`
+//! and `ot_apply.rs`), then asserts the result equals `resultText`.
+//!
+//! Applying a changeset only produces TEXT — attribute pools annotate spans but
+//! do not change the resulting characters — so the pool field is loaded for
+//! fidelity with core's fixture schema but is not needed to verify the text
+//! outcome.
+//!
+//! The fixture path is overridable via `ETHERPAD_WIRE_VECTORS` so core CI can
+//! inject a fresh copy; it defaults to the vendored
+//! `tests/fixtures/wire-vectors.json`.
+
+use etherpad_client::changeset::parser::parse;
+use etherpad_client::ot::apply;
+use serde::Deserialize;
+use std::collections::BTreeMap;
+use std::fs;
+use std::path::PathBuf;
+
+#[derive(Deserialize)]
+struct Pool {
+    #[serde(rename = "numToAttrib", default)]
+    #[allow(dead_code)]
+    num_to_attrib: BTreeMap<String, Vec<String>>,
+    #[serde(rename = "nextNum", default)]
+    #[allow(dead_code)]
+    next_num: u32,
+}
+
+#[derive(Deserialize)]
+struct Vector {
+    name: String,
+    #[serde(rename = "initialText")]
+    initial_text: String,
+    changeset: String,
+    #[allow(dead_code)]
+    pool: Pool,
+    #[serde(rename = "resultText")]
+    result_text: String,
+}
+
+fn vectors_path() -> PathBuf {
+    match std::env::var("ETHERPAD_WIRE_VECTORS") {
+        Ok(p) if !p.is_empty() => PathBuf::from(p),
+        _ => PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("tests/fixtures/wire-vectors.json"),
+    }
+}
+
+#[test]
+fn wire_vectors() {
+    let path = vectors_path();
+    let raw = fs::read_to_string(&path)
+        .unwrap_or_else(|e| panic!("read wire vectors {}: {e}", path.display()));
+    let vectors: Vec<Vector> = serde_json::from_str(&raw)
+        .unwrap_or_else(|e| panic!("parse wire vectors {}: {e}", path.display()));
+
+    assert!(
+        !vectors.is_empty(),
+        "wire vectors file {} is empty",
+        path.display()
+    );
+
+    let mut failures = Vec::new();
+    for v in &vectors {
+        let cs = match parse(&v.changeset) {
+            Ok(cs) => cs,
+            Err(e) => {
+                failures.push(format!("{}: parse failed: {e}", v.name));
+                continue;
+            }
+        };
+        match apply(&cs, &v.initial_text) {
+            Ok(actual) if actual == v.result_text => {
+                eprintln!("ok: {}", v.name);
+            }
+            Ok(actual) => failures.push(format!(
+                "{}: apply mismatch\n  expected {:?}\n  got      {:?}",
+                v.name, v.result_text, actual
+            )),
+            Err(e) => failures.push(format!("{}: apply failed: {e}", v.name)),
+        }
+    }
+
+    assert!(
+        failures.is_empty(),
+        "{} of {} wire vectors failed:\n{}",
+        failures.len(),
+        vectors.len(),
+        failures.join("\n")
+    );
+}