mnemo-engine 0.6.0

//! Smoke tests for the `mnemo` CLI exploration commands (`get`, `list`,
//! `recall`).
//!
//! These tests build a tiny database with the library, then invoke the
//! freshly built `mnemo` binary via [`std::process::Command`], asserting on
//! exit code and standard-output substrings. They are deliberately light:
//! the library API is exercised by `tests/integration.rs`; this file only
//! verifies that the CLI wiring around `db.get` / `db.memories` / `db.recall`
//! parses arguments and renders output as expected.

use std::process::Command;

use mnemo::{KdfParams, Memory, MemoryType, Mnemo, MnemoConfig};
use tempfile::tempdir;

/// Path to the `mnemo` binary built by Cargo for these tests.
fn bin() -> &'static str {
    env!("CARGO_BIN_EXE_mnemo")
}

/// Cheap KDF so the tests are fast.
fn fast_cfg(dimensions: usize) -> MnemoConfig {
    MnemoConfig {
        dimensions,
        kdf: KdfParams::fast(),
        ..Default::default()
    }
}

/// Create a tiny test database with three memories and return (path,
/// passphrase, id-of-the-semantic-memory).
fn seed_db() -> (tempfile::TempDir, std::path::PathBuf, &'static str, String) {
    let dir = tempdir().unwrap();
    let path = dir.path().join("smoke.mnemo");
    let pp = "smoke-pw";

    let mut db = Mnemo::create(&path, pp, fast_cfg(4)).unwrap();
    let semantic_id = db
        .remember(
            Memory::new(
                "the user prefers tea",
                MemoryType::Semantic,
                vec![1.0, 0.0, 0.0, 0.0],
            )
            .with_agent("assistant")
            .with_importance(0.9),
        )
        .unwrap();
    db.remember(
        Memory::new(
            "ran the deploy script",
            MemoryType::Episodic,
            vec![0.0, 1.0, 0.0, 0.0],
        )
        .with_agent("assistant")
        .with_importance(0.4),
    )
    .unwrap();
    db.remember(
        Memory::new(
            "escalate via pager",
            MemoryType::Procedural,
            vec![0.0, 0.0, 1.0, 0.0],
        )
        .with_agent("ops")
        .with_importance(0.6),
    )
    .unwrap();
    db.flush().unwrap();
    db.close().unwrap();

    (dir, path, pp, semantic_id.to_string())
}

/// Run the CLI with `MNEMO_PASSPHRASE` and return (status, stdout, stderr).
fn run_cli(args: &[&str], pp: &str) -> (std::process::ExitStatus, String, String) {
    let out = Command::new(bin())
        .args(args)
        .env("MNEMO_PASSPHRASE", pp)
        .output()
        .expect("failed to invoke mnemo binary");
    let stdout = String::from_utf8_lossy(&out.stdout).into_owned();
    let stderr = String::from_utf8_lossy(&out.stderr).into_owned();
    (out.status, stdout, stderr)
}

#[test]
fn list_table_shows_three_memories() {
    let (_dir, path, pp, _) = seed_db();
    let (status, stdout, stderr) =
        run_cli(&["list", path.to_str().unwrap(), "--format", "table"], pp);
    assert!(status.success(), "list failed: {stderr}");
    assert!(
        stdout.contains("showing 3 of 3 memories"),
        "header missing: {stdout}"
    );
    assert!(
        stdout.contains("the user prefers tea"),
        "content missing: {stdout}"
    );
    assert!(stdout.contains("[semantic]"), "type tag missing: {stdout}");
}

#[test]
fn list_filters_by_type_and_agent() {
    let (_dir, path, pp, _) = seed_db();
    let (status, stdout, _) = run_cli(
        &[
            "list",
            path.to_str().unwrap(),
            "--type",
            "procedural",
            "--agent",
            "ops",
        ],
        pp,
    );
    assert!(status.success());
    assert!(stdout.contains("escalate via pager"));
    assert!(!stdout.contains("prefers tea"));
    assert!(!stdout.contains("deploy script"));
}

#[test]
fn list_json_emits_total_and_count() {
    let (_dir, path, pp, _) = seed_db();
    let (status, stdout, _) = run_cli(
        &[
            "list",
            path.to_str().unwrap(),
            "--format",
            "json",
            "--limit",
            "2",
        ],
        pp,
    );
    assert!(status.success());
    let v: serde_json::Value = serde_json::from_str(&stdout).expect("json output");
    assert_eq!(v["total"], 3);
    assert_eq!(v["count"], 2);
    let memories = v["memories"].as_array().expect("memories array");
    assert_eq!(memories.len(), 2);
    // Vector is stripped by default.
    assert!(
        memories[0].get("vector").is_none(),
        "vector should be omitted"
    );
}

#[test]
fn list_jsonl_with_vector_includes_embedding() {
    let (_dir, path, pp, _) = seed_db();
    let (status, stdout, _) = run_cli(
        &[
            "list",
            path.to_str().unwrap(),
            "--format",
            "jsonl",
            "--vector",
        ],
        pp,
    );
    assert!(status.success());
    let lines: Vec<&str> = stdout.lines().filter(|l| !l.is_empty()).collect();
    assert_eq!(lines.len(), 3);
    for line in &lines {
        let v: serde_json::Value = serde_json::from_str(line).expect("jsonl line");
        assert!(v["vector"].as_array().is_some(), "missing vector: {line}");
    }
}

#[test]
fn get_by_id_table_and_json() {
    let (_dir, path, pp, semantic_id) = seed_db();

    let (status, stdout, _) = run_cli(
        &["get", path.to_str().unwrap(), &semantic_id, "--verbose"],
        pp,
    );
    assert!(status.success());
    assert!(
        stdout.contains(&semantic_id),
        "id missing in table output: {stdout}"
    );
    assert!(stdout.contains("the user prefers tea"));
    assert!(stdout.contains("imp=0.90"));
    assert!(stdout.contains("scope"));

    let (status, stdout, _) = run_cli(
        &[
            "get",
            path.to_str().unwrap(),
            &semantic_id,
            "--format",
            "json",
        ],
        pp,
    );
    assert!(status.success());
    let v: serde_json::Value = serde_json::from_str(&stdout).expect("json from get");
    assert_eq!(v["content"], "the user prefers tea");
    assert_eq!(v["memory_type"], "Semantic");
    assert!(
        v.get("vector").is_none(),
        "vector should be omitted by default"
    );
}

#[test]
fn get_missing_id_fails_cleanly() {
    let (_dir, path, pp, _) = seed_db();
    // A valid ULID that isn't in the DB.
    let (status, _stdout, stderr) = run_cli(
        &["get", path.to_str().unwrap(), "01ARZ3NDEKTSV4RRFFQ69G5FAV"],
        pp,
    );
    assert!(!status.success(), "missing id should exit non-zero");
    assert!(
        stderr.contains("not found"),
        "expected NotFound message, got: {stderr}"
    );
}

#[test]
fn recall_returns_query_nearest_first() {
    let (_dir, path, pp, _) = seed_db();
    let (status, stdout, _) = run_cli(
        &[
            "recall",
            path.to_str().unwrap(),
            "--query",
            "0.9,0.1,0.0,0.0",
            "--top-k",
            "2",
        ],
        pp,
    );
    assert!(status.success());
    let first_line = stdout.lines().next().unwrap_or("");
    assert!(
        first_line.contains("the user prefers tea"),
        "expected tea first: {stdout}"
    );
    assert!(first_line.starts_with("score="));
}

#[test]
fn recall_json_carries_score_and_similarity() {
    let (_dir, path, pp, _) = seed_db();
    let (status, stdout, _) = run_cli(
        &[
            "recall",
            path.to_str().unwrap(),
            "--query",
            "0.9,0.1,0.0,0.0",
            "--top-k",
            "1",
            "--format",
            "json",
        ],
        pp,
    );
    assert!(status.success());
    let v: serde_json::Value = serde_json::from_str(&stdout).expect("json from recall");
    assert_eq!(v["count"], 1);
    let hits = v["hits"].as_array().expect("hits array");
    assert!(hits[0]["score"].is_number());
    assert!(hits[0]["similarity"].is_number());
    assert_eq!(hits[0]["memory"]["content"], "the user prefers tea");
}

#[test]
fn recall_filters_by_type_excludes_other_kinds() {
    let (_dir, path, pp, _) = seed_db();
    let (status, stdout, _) = run_cli(
        &[
            "recall",
            path.to_str().unwrap(),
            "--query",
            "1.0,0.0,0.0,0.0",
            "--type",
            "procedural",
        ],
        pp,
    );
    assert!(status.success());
    // Only the procedural memory should appear.
    assert!(stdout.contains("escalate via pager"));
    assert!(!stdout.contains("prefers tea"));
    assert!(!stdout.contains("deploy script"));
}

#[test]
fn recall_query_file_json_works() {
    // --query-file accepts a JSON array of floats from a file path, as an
    // alternative to inline --query (which is unusable at high dims).
    let (dir, path, pp, _) = seed_db();
    let qf = dir.path().join("q.json");
    std::fs::write(&qf, "[1.0, 0.0, 0.0, 0.0]").unwrap();
    let (status, stdout, stderr) = run_cli(
        &[
            "recall",
            path.to_str().unwrap(),
            "--query-file",
            qf.to_str().unwrap(),
            "--top-k",
            "1",
        ],
        pp,
    );
    assert!(status.success(), "recall failed: {stderr}");
    assert!(stdout.contains("the user prefers tea"), "got: {stdout}");
}

#[test]
fn recall_query_file_whitespace_works() {
    // --query-file also accepts whitespace/newline-separated floats — handy
    // for piping from awk/jq without JSON serialization.
    let (dir, path, pp, _) = seed_db();
    let qf = dir.path().join("q.txt");
    std::fs::write(&qf, "1.0\n0.0\n0.0\n0.0\n").unwrap();
    let (status, stdout, stderr) = run_cli(
        &[
            "recall",
            path.to_str().unwrap(),
            "--query-file",
            qf.to_str().unwrap(),
            "--top-k",
            "1",
        ],
        pp,
    );
    assert!(status.success(), "recall failed: {stderr}");
    assert!(stdout.contains("the user prefers tea"), "got: {stdout}");
}

#[test]
fn recall_requires_query_source() {
    // Neither --query nor --query-file should fail loudly rather than silently
    // running with no query.
    let (_dir, path, pp, _) = seed_db();
    let (status, _stdout, stderr) =
        run_cli(&["recall", path.to_str().unwrap(), "--top-k", "1"], pp);
    assert!(!status.success(), "recall without query should fail");
    assert!(
        stderr.contains("--query") || stderr.contains("query"),
        "stderr should mention missing query, got: {stderr}"
    );
}

// === MCP stdio server ====================================================

/// Drive the MCP server end-to-end: spawn `mnemo serve --mcp <path>`,
/// pipe a scripted JSON-RPC session through stdin, capture stdout, and
/// assert the responses. Uses one long-lived child process rather than
/// one per request so we exercise the actual line-oriented dispatch loop.
#[test]
fn mcp_serve_initialize_list_and_call_tools() {
    use std::io::Write;
    use std::process::{Command, Stdio};

    // Seed the file with a *scoped* writer so its exclusive lock is
    // released before the server subprocess tries to acquire its own.
    // The temp dir stays alive for the whole test so the file survives.
    let dir = tempdir().unwrap();
    let path = dir.path().join("mcp.mnemo");
    let pp = "smoke-pw";
    {
        let mut db = Mnemo::create(&path, pp, fast_cfg(4)).unwrap();
        db.remember(
            Memory::new(
                "the user prefers tea",
                MemoryType::Semantic,
                vec![1.0, 0.0, 0.0, 0.0],
            )
            .with_importance(0.9),
        )
        .unwrap();
        db.flush().unwrap();
    }

    // ---- Race note (Linux only, observed on Rust 1.75 MSRV CI, 2026-08-29) ----
    // cargo runs `integration.rs` and `cli_smoke.rs` in parallel; several
    // integration tests fork subprocesses of their own via `Command::spawn`.
    // On Rust 1.75 Linux, `Command::spawn` still uses fork+exec, which
    // briefly clones ALL parent FDs into the sibling child before exec's
    // CLOEXEC pass drops them. If a sibling test forks while our own
    // scoped seed writer above is mid-drop, an inherited copy of the
    // writer's FD can keep the flock on `mcp.mnemo` alive for a few
    // milliseconds after our writer's `db` has dropped. Our `mnemo serve
    // --mcp` subprocess then loses the race for `try_lock_exclusive` and
    // exits with `MnemoError::Locked`. Stable Rust switched `spawn` to
    // `posix_spawn`, which skips the FD-clone window, so this reproduces
    // only on the MSRV Linux job.
    //
    // Fix scope: **test-only retry**. We re-spawn the whole session up
    // to 5 times with 100/200/400/800 ms backoff, but ONLY when the
    // child stderr carries the specific `file already locked` marker.
    // Any other non-zero exit falls through to the normal assertion
    // below with the same panic message it used to have. Do not weaken
    // the engine — the exclusive lock is a correctness invariant for
    // Phase 1.1; the race is inherent to fork+exec-plus-parallel-tests
    // on 1.75 and cannot recur once the process is stable.
    // -------------------------------------------------------------------------
    let mut out_opt = None;
    let mut last_stderr = String::new();
    for attempt in 0..5u32 {
        if attempt > 0 {
            // 100 ms → 200 → 400 → 800; cumulative worst case ~1.5 s.
            let backoff_ms = 100u64 << (attempt - 1);
            std::thread::sleep(std::time::Duration::from_millis(backoff_ms));
        }
        let mut child = Command::new(bin())
            .args(["serve", path.to_str().unwrap(), "--mcp"])
            .env("MNEMO_PASSPHRASE", pp)
            .stdin(Stdio::piped())
            .stdout(Stdio::piped())
            .stderr(Stdio::piped())
            .spawn()
            .expect("failed to spawn mnemo serve --mcp");

        // Scripted client session: initialize, then list tools, then call
        // `stats`. Each line is one JSON-RPC message. Closing stdin ends
        // the loop and the child exits.
        let stdin = child.stdin.as_mut().expect("child stdin missing");
        let script = [
            r#"{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{}}}"#,
            r#"{"jsonrpc":"2.0","method":"notifications/initialized","params":{}}"#,
            r#"{"jsonrpc":"2.0","id":2,"method":"tools/list","params":{}}"#,
            r#"{"jsonrpc":"2.0","id":3,"method":"tools/call","params":{"name":"stats","arguments":{}}}"#,
        ];
        for line in script {
            writeln!(stdin, "{line}").unwrap();
        }
        // Close stdin — signals EOF to the server's read loop.
        drop(child.stdin.take());

        // Wait for shutdown (bounded — the server should exit as soon as
        // stdin closes; hanging here would fail the test with a timeout
        // at the test-runner level).
        let run = child.wait_with_output().expect("child wait failed");
        if !run.status.success() {
            let stderr_snapshot = String::from_utf8_lossy(&run.stderr).into_owned();
            if stderr_snapshot.contains("file already locked") {
                // Race lost — retry after backoff.
                last_stderr = stderr_snapshot;
                continue;
            }
            // Any other failure: bubble up unchanged.
            out_opt = Some(run);
            break;
        }
        out_opt = Some(run);
        break;
    }
    let out = out_opt.unwrap_or_else(|| {
        panic!(
            "mnemo serve --mcp lost the fork/flock race on all 5 attempts \
             (bounded retry exhausted); last stderr:\n{last_stderr}"
        )
    });
    let stdout = String::from_utf8_lossy(&out.stdout).into_owned();
    let stderr = String::from_utf8_lossy(&out.stderr).into_owned();
    assert!(
        out.status.success(),
        "server exited non-zero: status={:?} stderr={stderr}",
        out.status
    );

    // Parse the response lines back and assert on structure.
    let lines: Vec<&str> = stdout.lines().filter(|l| !l.trim().is_empty()).collect();
    assert!(
        lines.len() >= 3,
        "expected ≥3 response lines (init, tools/list, stats), got {}: {stdout}",
        lines.len()
    );

    let init: serde_json::Value = serde_json::from_str(lines[0]).expect("init parse");
    assert_eq!(init["jsonrpc"], "2.0");
    assert_eq!(init["id"], 1);
    assert_eq!(init["result"]["protocolVersion"], "2025-06-18");
    assert_eq!(init["result"]["serverInfo"]["name"], "mnemo");

    let list: serde_json::Value = serde_json::from_str(lines[1]).expect("tools/list parse");
    let tools = list["result"]["tools"].as_array().expect("tools array");
    let names: Vec<&str> = tools.iter().filter_map(|t| t["name"].as_str()).collect();
    for expected in [
        "about",
        "remember",
        "recall",
        "forget",
        "list",
        "snapshot_list",
        "stats",
    ] {
        assert!(
            names.contains(&expected),
            "missing tool '{expected}' in {names:?}"
        );
    }

    let stats: serde_json::Value = serde_json::from_str(lines[2]).expect("stats parse");
    let content = &stats["result"]["content"][0]["text"];
    assert!(
        content.is_string(),
        "stats content should be a text block: {stats}"
    );
    let stats_body: serde_json::Value =
        serde_json::from_str(content.as_str().unwrap()).expect("stats body parse");
    assert_eq!(
        stats_body["memories"], 1,
        "seeded exactly one live memory: {stats_body}"
    );
}

#[test]
fn mcp_serve_refuses_without_passphrase() {
    // Env var missing → server errors at startup with a clear message
    // and non-zero exit, never opening the file.
    use std::process::{Command, Stdio};

    let dir = tempdir().unwrap();
    let path = dir.path().join("mcp-nopw.mnemo");
    {
        let mut db = Mnemo::create(&path, "smoke-pw", fast_cfg(4)).unwrap();
        db.remember(Memory::new(
            "x",
            MemoryType::Semantic,
            vec![1.0, 0.0, 0.0, 0.0],
        ))
        .unwrap();
        db.flush().unwrap();
    }

    let out = Command::new(bin())
        .args(["serve", path.to_str().unwrap(), "--mcp"])
        .env_remove("MNEMO_PASSPHRASE")
        .stdin(Stdio::null())
        .stdout(Stdio::piped())
        .stderr(Stdio::piped())
        .output()
        .expect("spawn failed");
    let stderr = String::from_utf8_lossy(&out.stderr).into_owned();
    assert!(
        !out.status.success(),
        "expected non-zero exit without passphrase"
    );
    assert!(
        stderr.contains("MNEMO_PASSPHRASE"),
        "stderr should mention the env var, got: {stderr}"
    );
}

// === Phase 3 PR 10b: --embed-cmd / text params ============================
//
// Fake-embedder choice: inline Python. All three GitHub-Actions runners
// (ubuntu-latest, macos-latest, windows-latest) ship Python 3 by default.
// Rust-helper-binary alternatives would need either a published `[[bin]]`
// (clutters the shipped crate) or a `[[example]]` + hard-coded relative
// path (brittle on parallel-test layouts). Python is one import away on
// every supported CI target, keeps the fake embedder as a 10-line
// readable artifact rather than another compilation unit, and matches
// what real users will typically use (sentence-transformers in Python).

/// Platform-appropriate name of the Python 3 interpreter. On Linux and
/// macOS CI images, `python3` is on PATH. On Windows CI images,
/// `python` is on PATH (and `python3` may or may not be).
fn python_cmd() -> &'static str {
    if cfg!(windows) {
        "python"
    } else {
        "python3"
    }
}

/// Write a Python script into a tempfile and return its path.
/// Caller keeps the tempfile alive for the duration of the subprocess.
fn write_py_script(dir: &std::path::Path, name: &str, body: &str) -> std::path::PathBuf {
    let p = dir.join(name);
    std::fs::write(&p, body).unwrap();
    p
}

/// Deterministic text-dependent 4-D fake embedder (PR 10b.2). The
/// vector encodes `len(text)` on one hash-selected axis, so tests
/// can assert that a reply was embedded from the right input and
/// catch misalignment (if EmbedCmd ever handed back a stale leftover
/// line, the lengths wouldn't match).
///
/// Also implements four special triggers for the respawn / timeout /
/// alignment tests:
///   - "HANG"   → block forever (never writes a reply).
///   - "JUNK"   → emit a non-JSON line.
///   - "DOUBLE" → emit two reply lines for one input.
///   - everything else → the normal text-dependent reply.
const FAKE_EMBED_PY: &str = r#"
import sys, json, time
DIMS = 4
def encode(s):
    axis = sum(bytearray(s.encode("utf-8"))) % DIMS
    v = [0.0] * DIMS
    v[axis] = float(len(s)) + 1.0  # non-zero, text-dependent
    return v
for line in sys.stdin:
    s = json.loads(line)
    if s == "HANG":
        time.sleep(3600)
    elif s == "JUNK":
        print("not-valid-json", flush=True)
    elif s == "DOUBLE":
        print(json.dumps(encode(s)), flush=True)
        print(json.dumps(encode("stowaway")), flush=True)
    else:
        print(json.dumps(encode(s)), flush=True)
"#;

/// Python helper that encodes a text the same way `FAKE_EMBED_PY`
/// does, invoked from tests to compute an expected vector.
fn fake_vector_for(text: &str) -> Vec<f32> {
    let axis = text.bytes().map(|b| b as usize).sum::<usize>() % 4;
    let mut v = vec![0.0f32; 4];
    v[axis] = text.len() as f32 + 1.0;
    v
}

/// Fake embedder that prints an unsolicited startup banner to stdout
/// before entering the read loop (common Python-logging footgun).
/// EmbedCmd must detect the extra line and refuse to proceed.
const BANNER_EMBED_PY: &str = r#"
import sys, json
print("[banner] model loaded", flush=True)
DIMS = 4
for line in sys.stdin:
    s = json.loads(line)
    axis = sum(bytearray(s.encode("utf-8"))) % DIMS
    v = [0.0] * DIMS
    v[axis] = float(len(s)) + 1.0
    print(json.dumps(v), flush=True)
"#;

/// Fake embedder that reads one line, then exits non-zero — exercises
/// the "child crashed mid-session" branch of EmbedCmd.
const CRASHING_EMBED_PY: &str = r#"
import sys, json
for line in sys.stdin:
    _ = json.loads(line)
    sys.exit(1)
"#;

/// Fake embedder that returns the wrong width (2 dims instead of 4).
const WRONG_WIDTH_EMBED_PY: &str = r#"
import sys, json
for line in sys.stdin:
    _ = json.loads(line)
    print(json.dumps([1.0, 2.0]), flush=True)
"#;

/// Fake embedder that returns an all-zero vector of the correct width —
/// FIX-1 R-001.6: this must be rejected via `fail_and_restart` even
/// though its length and JSON shape are both fine, because an all-zero
/// vector cannot be scored by cosine or dot-product similarity.
const ZERO_VECTOR_EMBED_PY: &str = r#"
import sys, json
for line in sys.stdin:
    _ = json.loads(line)
    print(json.dumps([0.0, 0.0, 0.0, 0.0]), flush=True)
"#;

/// Fake embedder that returns a vector containing a value that
/// overflows `f32` — `1e40` is above `f32::MAX` (~3.4e38), so
/// serde_json decodes it as `f32::INFINITY`. FIX-1 R-001.6: any
/// non-finite value (±∞ or, through a non-standard JSON decoder,
/// NaN) must fail-and-restart. We drive the check through +∞
/// because standard JSON doesn't allow a bare `NaN` token —
/// serde_json rejects that at parse time (and surfaces as
/// "malformed JSON" on its own), so a Python `math.nan` would
/// never reach the finiteness check we care about here.
const NON_FINITE_VECTOR_EMBED_PY: &str = r#"
import sys, json
for line in sys.stdin:
    _ = json.loads(line)
    print(json.dumps([1.0, 1e40, 2.0, 3.0]), flush=True)
"#;

/// Fake embedder that touches a marker file on startup. Used to verify
/// the child is spawned once across multiple MCP tool calls.
/// Vector is text-dependent (PR 10b.2 convention).
const STARTUP_MARKER_EMBED_PY: &str = r#"
import sys, json, os
with open(os.environ["MNEMO_TEST_MARKER"], "a") as f:
    f.write("start\n")
DIMS = 4
for line in sys.stdin:
    s = json.loads(line)
    axis = sum(bytearray(s.encode("utf-8"))) % DIMS
    v = [0.0] * DIMS
    v[axis] = float(len(s)) + 1.0
    print(json.dumps(v), flush=True)
"#;

fn embed_cmd_arg(script_path: &std::path::Path) -> String {
    // Quote the path so shlex_split in EmbedCmd parses it as one argv
    // entry even if the tempdir contains spaces (common on Windows CI
    // where runner paths include "runneradmin").
    format!("{} \"{}\"", python_cmd(), script_path.display())
}

#[test]
fn cli_remember_and_recall_text_round_trip() {
    let dir = tempdir().unwrap();
    let path = dir.path().join("em.mnemo");
    let pp = "em-pw";
    // Seed with the scaffold manifest so `set_embedder` has a target
    // for the identity write.
    {
        let mut db = Mnemo::create(&path, pp, fast_cfg(4)).unwrap();
        db.remember(Memory::scaffold_manifest(4)).unwrap();
        db.flush().unwrap();
    }
    let script = write_py_script(dir.path(), "fake.py", FAKE_EMBED_PY);
    let ecmd = embed_cmd_arg(&script);

    // mnemo remember --text "alpha" --embed-cmd '…' --embed-name fake-4d
    let out = Command::new(bin())
        .args([
            "remember",
            path.to_str().unwrap(),
            "--text",
            "alpha",
            "--embed-cmd",
            &ecmd,
            "--embed-name",
            "fake-4d",
            "--embed-normalize",
            "true",
        ])
        .env("MNEMO_PASSPHRASE", pp)
        .output()
        .expect("spawn mnemo remember");
    assert!(
        out.status.success(),
        "mnemo remember failed: status={:?} stdout={} stderr={}",
        out.status,
        String::from_utf8_lossy(&out.stdout),
        String::from_utf8_lossy(&out.stderr),
    );
    // Stdout should be a ULID (one line, 26 chars).
    let ulid = String::from_utf8(out.stdout).unwrap();
    assert!(
        ulid.trim().len() >= 26,
        "expected a ULID on stdout, got {ulid:?}"
    );

    // mnemo recall --text "alpha" ... → the just-stored memory should
    // surface first.
    let out = Command::new(bin())
        .args([
            "recall",
            path.to_str().unwrap(),
            "--text",
            "alpha",
            "--embed-cmd",
            &ecmd,
            "--embed-name",
            "fake-4d",
            "--top-k",
            "5",
            "--format",
            "json",
            "--no-track",
        ])
        .env("MNEMO_PASSPHRASE", pp)
        .output()
        .expect("spawn mnemo recall");
    assert!(
        out.status.success(),
        "mnemo recall failed: status={:?} stderr={}",
        out.status,
        String::from_utf8_lossy(&out.stderr),
    );
    let stdout = String::from_utf8(out.stdout).unwrap();
    assert!(
        stdout.contains("alpha"),
        "recall --text output should contain the stored content, got: {stdout}"
    );
}

#[test]
fn cli_recall_text_without_embed_cmd_errors_cleanly() {
    let dir = tempdir().unwrap();
    let path = dir.path().join("em-noec.mnemo");
    let pp = "em-pw";
    {
        let _ = Mnemo::create(&path, pp, fast_cfg(4)).unwrap();
    }
    let out = Command::new(bin())
        .args([
            "recall",
            path.to_str().unwrap(),
            "--text",
            "alpha",
            // Deliberately NO --embed-cmd / --embed-name.
        ])
        .env("MNEMO_PASSPHRASE", pp)
        .output()
        .expect("spawn mnemo recall");
    assert!(
        !out.status.success(),
        "recall --text without --embed-cmd should fail"
    );
    let combined = format!(
        "{}{}",
        String::from_utf8_lossy(&out.stdout),
        String::from_utf8_lossy(&out.stderr)
    );
    assert!(
        combined.to_lowercase().contains("embed"),
        "error should mention embedder, got: {combined}"
    );
}

#[test]
fn cli_remember_text_crashing_embedder_errors_cleanly() {
    let dir = tempdir().unwrap();
    let path = dir.path().join("em-crash.mnemo");
    let pp = "em-pw";
    {
        let _ = Mnemo::create(&path, pp, fast_cfg(4)).unwrap();
    }
    let script = write_py_script(dir.path(), "crash.py", CRASHING_EMBED_PY);
    let ecmd = embed_cmd_arg(&script);
    let out = Command::new(bin())
        .args([
            "remember",
            path.to_str().unwrap(),
            "--text",
            "boom",
            "--embed-cmd",
            &ecmd,
            "--embed-name",
            "fake-4d",
        ])
        .env("MNEMO_PASSPHRASE", pp)
        .output()
        .expect("spawn mnemo remember");
    assert!(
        !out.status.success(),
        "remember with a crashing embedder should fail"
    );
    let stderr = String::from_utf8_lossy(&out.stderr);
    // Either the child "exited before this request" (if we noticed the
    // first-call exit before writing) OR a protocol/read failure after.
    // Both are acceptable; the point is a clear non-zero exit.
    assert!(
        stderr.to_lowercase().contains("embed-cmd") || stderr.to_lowercase().contains("embedder"),
        "stderr should mention the embedder failure, got: {stderr}"
    );
}

#[test]
fn cli_remember_text_wrong_width_errors_cleanly() {
    let dir = tempdir().unwrap();
    let path = dir.path().join("em-ww.mnemo");
    let pp = "em-pw";
    {
        let _ = Mnemo::create(&path, pp, fast_cfg(4)).unwrap();
    }
    let script = write_py_script(dir.path(), "ww.py", WRONG_WIDTH_EMBED_PY);
    let ecmd = embed_cmd_arg(&script);
    let out = Command::new(bin())
        .args([
            "remember",
            path.to_str().unwrap(),
            "--text",
            "two-dims",
            "--embed-cmd",
            &ecmd,
            "--embed-name",
            "fake-4d",
        ])
        .env("MNEMO_PASSPHRASE", pp)
        .output()
        .expect("spawn mnemo remember");
    assert!(
        !out.status.success(),
        "remember with wrong-width embedder should fail"
    );
    let stderr = String::from_utf8_lossy(&out.stderr);
    assert!(
        stderr.contains("dim") || stderr.contains("2"),
        "stderr should mention the dimension mismatch, got: {stderr}"
    );
}

#[test]
fn mcp_serve_with_embedder_text_params_and_persistent_child() {
    use std::io::Write;
    use std::process::{Command, Stdio};

    let dir = tempdir().unwrap();
    let path = dir.path().join("mcp-em.mnemo");
    let pp = "em-pw";
    // Seed with the scaffold manifest so the embedder's identity has
    // somewhere to land on set_embedder.
    {
        let mut db = Mnemo::create(&path, pp, fast_cfg(4)).unwrap();
        db.remember(Memory::scaffold_manifest(4)).unwrap();
        db.flush().unwrap();
    }
    let marker = dir.path().join("startup.marker");
    let script = write_py_script(dir.path(), "startup.py", STARTUP_MARKER_EMBED_PY);
    let ecmd = embed_cmd_arg(&script);

    // Same retry-on-flock-race pattern as the plain mcp_serve test.
    let mut out_opt = None;
    let mut last_stderr = String::new();
    for attempt in 0..5u32 {
        if attempt > 0 {
            let backoff_ms = 100u64 << (attempt - 1);
            std::thread::sleep(std::time::Duration::from_millis(backoff_ms));
        }
        let mut child = Command::new(bin())
            .args([
                "serve",
                path.to_str().unwrap(),
                "--mcp",
                "--embed-cmd",
                &ecmd,
                "--embed-name",
                "fake-4d",
            ])
            .env("MNEMO_PASSPHRASE", pp)
            .env("MNEMO_TEST_MARKER", &marker)
            .stdin(Stdio::piped())
            .stdout(Stdio::piped())
            .stderr(Stdio::piped())
            .spawn()
            .expect("failed to spawn mnemo serve --mcp");

        let stdin = child.stdin.as_mut().expect("child stdin missing");
        // Three tool/call messages that go through the embedder, plus
        // the initialize dance. If the child is reused the marker file
        // ends with one line; if a new child spawned per call it would
        // have three.
        let script = [
            r#"{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{}}}"#,
            r#"{"jsonrpc":"2.0","method":"notifications/initialized","params":{}}"#,
            r#"{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"remember","arguments":{"content":"alpha","memory_type":"semantic","text":"alpha"}}}"#,
            r#"{"jsonrpc":"2.0","id":3,"method":"tools/call","params":{"name":"remember","arguments":{"content":"beta","memory_type":"semantic","text":"beta"}}}"#,
            r#"{"jsonrpc":"2.0","id":4,"method":"tools/call","params":{"name":"recall","arguments":{"text":"alpha","top_k":5}}}"#,
        ];
        for line in script {
            writeln!(stdin, "{line}").unwrap();
        }
        drop(child.stdin.take());

        let out = child.wait_with_output().expect("child wait");
        last_stderr = String::from_utf8_lossy(&out.stderr).to_string();
        if out.status.success() {
            out_opt = Some(out);
            break;
        }
        if !last_stderr.contains("file already locked") {
            panic!(
                "mnemo serve --mcp failed (attempt {attempt}): status={:?} stderr={last_stderr}",
                out.status
            );
        }
    }
    let out = out_opt.unwrap_or_else(|| {
        panic!("mnemo serve --mcp never acquired the lock: stderr={last_stderr}")
    });

    let stdout = String::from_utf8_lossy(&out.stdout);
    assert!(
        stdout.contains("\"id\":2"),
        "expected a response to remember call id 2, got stdout: {stdout}"
    );
    assert!(
        stdout.contains("\"id\":4"),
        "expected a response to recall call id 4, got stdout: {stdout}"
    );
    // alpha must come back on the recall; the fake embedder is
    // deterministic so axis-of-"alpha" matches axis-of-"alpha".
    assert!(
        stdout.contains("alpha"),
        "expected 'alpha' in recall output, got: {stdout}"
    );
    // Marker file should have exactly ONE startup line — persistent child.
    let marker_text = std::fs::read_to_string(&marker).unwrap_or_default();
    let starts = marker_text.lines().filter(|l| *l == "start").count();
    assert_eq!(
        starts, 1,
        "embedder child should have started once; marker file: {marker_text:?}"
    );
}

#[test]
fn mcp_text_param_without_embedder_returns_helpful_error() {
    use std::io::Write;
    use std::process::{Command, Stdio};

    let dir = tempdir().unwrap();
    let path = dir.path().join("mcp-noem.mnemo");
    let pp = "em-pw";
    {
        let _ = Mnemo::create(&path, pp, fast_cfg(4)).unwrap();
    }

    let mut out_opt = None;
    let mut last_stderr = String::new();
    for attempt in 0..5u32 {
        if attempt > 0 {
            let backoff_ms = 100u64 << (attempt - 1);
            std::thread::sleep(std::time::Duration::from_millis(backoff_ms));
        }
        let mut child = Command::new(bin())
            // No --embed-cmd / --embed-name.
            .args(["serve", path.to_str().unwrap(), "--mcp"])
            .env("MNEMO_PASSPHRASE", pp)
            .stdin(Stdio::piped())
            .stdout(Stdio::piped())
            .stderr(Stdio::piped())
            .spawn()
            .expect("spawn mnemo serve --mcp");
        let stdin = child.stdin.as_mut().unwrap();
        let script = [
            r#"{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{}}}"#,
            r#"{"jsonrpc":"2.0","method":"notifications/initialized","params":{}}"#,
            r#"{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"recall","arguments":{"text":"anything"}}}"#,
        ];
        for line in script {
            writeln!(stdin, "{line}").unwrap();
        }
        drop(child.stdin.take());
        let out = child.wait_with_output().expect("child wait");
        last_stderr = String::from_utf8_lossy(&out.stderr).to_string();
        if out.status.success() {
            out_opt = Some(out);
            break;
        }
        if !last_stderr.contains("file already locked") {
            panic!(
                "mnemo serve --mcp failed (attempt {attempt}): status={:?} stderr={last_stderr}",
                out.status
            );
        }
    }
    let out = out_opt.unwrap_or_else(|| {
        panic!("mnemo serve --mcp never acquired the lock: stderr={last_stderr}")
    });
    let stdout = String::from_utf8_lossy(&out.stdout);
    // The recall call should surface an RPC error pointing at
    // --embed-cmd / --embed-name.
    assert!(
        stdout.contains("--embed-cmd") || stdout.contains("embedder"),
        "expected a helpful error mentioning --embed-cmd, got: {stdout}"
    );
}

// === Phase 3 PR 10b.2: timeout, respawn, alignment =======================

#[test]
fn cli_remember_text_hang_times_out_bounded() {
    // The fake blocks forever on "HANG". With --embed-timeout 2 the
    // CLI must error well under its default 60s. Elapsed-time bound
    // of 20s is deliberately loose to absorb CI variance; the correct
    // timeout fires ~2–3s in.
    let dir = tempdir().unwrap();
    let path = dir.path().join("hang.mnemo");
    let pp = "em-pw";
    {
        let _ = Mnemo::create(&path, pp, fast_cfg(4)).unwrap();
    }
    let script = write_py_script(dir.path(), "hang.py", FAKE_EMBED_PY);
    let ecmd = embed_cmd_arg(&script);
    let start = std::time::Instant::now();
    let out = Command::new(bin())
        .args([
            "remember",
            path.to_str().unwrap(),
            "--text",
            "HANG",
            "--embed-cmd",
            &ecmd,
            "--embed-name",
            "fake-4d",
            "--embed-timeout",
            "2",
        ])
        .env("MNEMO_PASSPHRASE", pp)
        .output()
        .expect("spawn mnemo remember");
    let elapsed = start.elapsed();
    assert!(
        !out.status.success(),
        "remember on HANG should error (child never replies)"
    );
    assert!(
        elapsed < std::time::Duration::from_secs(20),
        "hang must trip the --embed-timeout bound; elapsed={elapsed:?}"
    );
    let stderr = String::from_utf8_lossy(&out.stderr);
    assert!(
        stderr.contains("timed out") || stderr.contains("embed-cmd"),
        "stderr should name the timeout, got: {stderr}"
    );
}

#[test]
fn embed_cmd_recovers_after_junk_reply_with_correct_vector() {
    use mnemo::{EmbedCmd, Embedder, EmbedderIdentity};
    // Call "JUNK" → fake prints an invalid-JSON line → EmbedCmd errors
    // and kills the child. Next call for "abc" must respawn and return
    // abc's text-dependent vector, not a leftover.
    let dir = tempdir().unwrap();
    let script = write_py_script(dir.path(), "junk.py", FAKE_EMBED_PY);
    let ecmd = embed_cmd_arg(&script);
    let identity = EmbedderIdentity {
        name: "fake-4d".into(),
        dimensions: 4,
        normalize: true,
    };
    let em = EmbedCmd::new(&ecmd, identity)
        .unwrap()
        .with_timeout(std::time::Duration::from_secs(5));
    let err = em.embed(&["JUNK"]).unwrap_err();
    let msg = format!("{err}");
    assert!(
        msg.contains("malformed JSON") || msg.contains("respawn"),
        "JUNK should raise a protocol error, got: {msg}"
    );
    // Next call must respawn + return abc's actual vector.
    let out = em.embed(&["abc"]).unwrap();
    assert_eq!(out.len(), 1);
    assert_eq!(out[0], fake_vector_for("abc"));
}

#[test]
fn embed_cmd_recovers_after_double_reply_with_correct_vector() {
    use mnemo::{EmbedCmd, Embedder, EmbedderIdentity};
    // "DOUBLE" prints TWO lines for one input. The first is read as
    // the DOUBLE reply (fine); the second is a stale leftover. The
    // guard in `embed()` must detect it before writing the next
    // request OR the width check must catch the stray reply. Either
    // way, the next call for "abc" must return abc's vector.
    let dir = tempdir().unwrap();
    let script = write_py_script(dir.path(), "double.py", FAKE_EMBED_PY);
    let ecmd = embed_cmd_arg(&script);
    let identity = EmbedderIdentity {
        name: "fake-4d".into(),
        dimensions: 4,
        normalize: true,
    };
    let em = EmbedCmd::new(&ecmd, identity)
        .unwrap()
        .with_timeout(std::time::Duration::from_secs(5));
    // DOUBLE succeeds on this call (returns the first JSON line).
    let out = em.embed(&["DOUBLE"]).unwrap();
    assert_eq!(out.len(), 1);
    assert_eq!(out[0], fake_vector_for("DOUBLE"));
    // Give the background reader thread a moment to actually deliver
    // the stowaway line into the channel. Without this the drain-pass
    // on the next call can race the reader and miss it; we want to
    // test the detection path, not the race window.
    std::thread::sleep(std::time::Duration::from_millis(200));
    // The second (stale) line is now queued. Next call MUST either
    // detect-and-restart OR, if it slipped through, return the right
    // vector. Either way the result for "abc" must be abc's vector,
    // never the stowaway's.
    let next = em.embed(&["abc"]);
    match next {
        Ok(v) => {
            assert_eq!(v.len(), 1);
            assert_eq!(
                v[0],
                fake_vector_for("abc"),
                "next call MUST return abc's vector, never a leftover"
            );
        }
        Err(e) => {
            // Error is acceptable (planner: "an error is allowed; a
            // mismatched vector never is"). But a FOLLOWING call must
            // then succeed and return the right vector.
            let msg = format!("{e}");
            assert!(
                msg.contains("respawn") || msg.contains("outside a reply"),
                "if first call errors it must be a clear protocol error, got: {msg}"
            );
            let recovery = em.embed(&["abc"]).unwrap();
            assert_eq!(recovery[0], fake_vector_for("abc"));
        }
    }
}

#[test]
fn embed_cmd_rejects_all_zero_vector_and_respawns() {
    // FIX-1 R-001.6: an all-zero reply of the correct width must trip
    // `fail_and_restart`. Follow-up call for "abc" must spawn a fresh
    // child and return abc's real vector, not a leftover from the
    // offending reply.
    use mnemo::{EmbedCmd, Embedder, EmbedderIdentity};
    let dir = tempdir().unwrap();
    let script = write_py_script(dir.path(), "zero.py", ZERO_VECTOR_EMBED_PY);
    let ecmd = embed_cmd_arg(&script);
    let identity = EmbedderIdentity {
        name: "fake-4d".into(),
        dimensions: 4,
        normalize: true,
    };
    let em = EmbedCmd::new(&ecmd, identity)
        .unwrap()
        .with_timeout(std::time::Duration::from_secs(5));
    let err = em.embed(&["anything"]).unwrap_err();
    let msg = format!("{err}");
    assert!(
        msg.contains("all-zero") && msg.contains("respawn"),
        "zero vector must surface as the dedicated protocol error, got: {msg}"
    );
    // Follow-up spawns a fresh child (which will also return zeros,
    // because the script is deterministic). The point is that we
    // never got the zero vector *back* as a successful embed result.
    let err2 = em.embed(&["abc"]).unwrap_err();
    assert!(format!("{err2}").contains("all-zero"));
}

#[test]
fn embed_cmd_rejects_non_finite_vector_and_respawns() {
    // FIX-1 R-001.6: an ±∞ entry anywhere in the reply must trip
    // `fail_and_restart` even though the width is correct — a non-
    // finite similarity score poisons every ranked list it reaches.
    // We drive the check through `+∞` (produced by serde_json's f32
    // decoder on an overflowing JSON number like `1e40`) rather than
    // NaN, which standard JSON doesn't allow as a bare token and
    // serde_json rejects at parse time.
    use mnemo::{EmbedCmd, Embedder, EmbedderIdentity};
    let dir = tempdir().unwrap();
    let script = write_py_script(dir.path(), "non_finite.py", NON_FINITE_VECTOR_EMBED_PY);
    let ecmd = embed_cmd_arg(&script);
    let identity = EmbedderIdentity {
        name: "fake-4d".into(),
        dimensions: 4,
        normalize: true,
    };
    let em = EmbedCmd::new(&ecmd, identity)
        .unwrap()
        .with_timeout(std::time::Duration::from_secs(5));
    let err = em.embed(&["anything"]).unwrap_err();
    let msg = format!("{err}");
    assert!(
        msg.contains("non-finite") && msg.contains("respawn"),
        "±∞ reply must surface as the dedicated protocol error, got: {msg}"
    );
}

#[test]
fn embed_cmd_detects_stdout_banner_before_requests() {
    use mnemo::{EmbedCmd, Embedder, EmbedderIdentity};
    let dir = tempdir().unwrap();
    let script = write_py_script(dir.path(), "banner.py", BANNER_EMBED_PY);
    let ecmd = embed_cmd_arg(&script);
    let identity = EmbedderIdentity {
        name: "fake-4d".into(),
        dimensions: 4,
        normalize: true,
    };
    let em = EmbedCmd::new(&ecmd, identity)
        .unwrap()
        .with_timeout(std::time::Duration::from_secs(5));
    // Give the child a brief moment to print its banner before the
    // first embed() call runs its drain-pass; otherwise the race may
    // put the banner into the reply slot and we'd see a malformed-JSON
    // error instead. Either outcome is correct per the planner's rule
    // ("an error is allowed; a mismatched vector never is") but the
    // "stdout outside a reply" message is the clearer one.
    std::thread::sleep(std::time::Duration::from_millis(200));
    let err = em.embed(&["anything"]).unwrap_err();
    let msg = format!("{err}");
    assert!(
        msg.contains("stdout") || msg.contains("outside a reply") || msg.contains("malformed"),
        "banner should surface as a stdout-protocol error, got: {msg}"
    );
    // Note: we don't assert recovery here. BANNER_EMBED_PY is unusual
    // in that every respawn also prints a banner, so a follow-up call
    // will error again — the respawn mechanism is tested in the
    // JUNK/DOUBLE tests, which use a well-behaved fake after the
    // offending call. What we're pinning down here is just that a
    // startup banner surfaces as a clear protocol error, never as a
    // mismatched vector.
}

#[test]
fn embed_cmd_two_thousand_text_batch_does_not_deadlock() {
    use mnemo::{EmbedCmd, Embedder, EmbedderIdentity};
    // Pre-10b.2 (write-all-then-read-all) this would deadlock on a
    // batch big enough to fill the child's stdout pipe buffer. The
    // reader thread drains stdout in parallel with our stdin writes,
    // so a 2000-line batch completes in the normal path.
    let dir = tempdir().unwrap();
    let script = write_py_script(dir.path(), "batch.py", FAKE_EMBED_PY);
    let ecmd = embed_cmd_arg(&script);
    let identity = EmbedderIdentity {
        name: "fake-4d".into(),
        dimensions: 4,
        normalize: true,
    };
    let em = EmbedCmd::new(&ecmd, identity)
        .unwrap()
        .with_timeout(std::time::Duration::from_secs(30));
    // 2000 unique-ish texts so the fake doesn't short-circuit via a
    // trigger ("HANG"/"JUNK"/"DOUBLE").
    let texts: Vec<String> = (0..2000).map(|i| format!("text-{i:04}")).collect();
    let refs: Vec<&str> = texts.iter().map(|s| s.as_str()).collect();
    let out = em.embed(&refs).unwrap();
    assert_eq!(out.len(), 2000);
    // Spot-check a few vectors line up with their inputs.
    for i in [0, 123, 999, 1999] {
        assert_eq!(
            out[i],
            fake_vector_for(&texts[i]),
            "vector at index {i} must correspond to its input text"
        );
    }
}

#[test]
fn mcp_hang_bounded_and_server_survives_for_next_call() {
    use std::io::Write;
    use std::process::{Command, Stdio};

    let dir = tempdir().unwrap();
    let path = dir.path().join("mcp-hang.mnemo");
    let pp = "em-pw";
    {
        let mut db = Mnemo::create(&path, pp, fast_cfg(4)).unwrap();
        db.remember(Memory::scaffold_manifest(4)).unwrap();
        db.flush().unwrap();
    }
    let script = write_py_script(dir.path(), "hang.py", FAKE_EMBED_PY);
    let ecmd = embed_cmd_arg(&script);

    let mut out_opt = None;
    let mut last_stderr = String::new();
    for attempt in 0..5u32 {
        if attempt > 0 {
            let backoff_ms = 100u64 << (attempt - 1);
            std::thread::sleep(std::time::Duration::from_millis(backoff_ms));
        }
        let mut child = Command::new(bin())
            .args([
                "serve",
                path.to_str().unwrap(),
                "--mcp",
                "--embed-cmd",
                &ecmd,
                "--embed-name",
                "fake-4d",
                "--embed-timeout",
                "2",
            ])
            .env("MNEMO_PASSPHRASE", pp)
            .stdin(Stdio::piped())
            .stdout(Stdio::piped())
            .stderr(Stdio::piped())
            .spawn()
            .expect("spawn mnemo serve --mcp");

        let stdin = child.stdin.as_mut().unwrap();
        // HANG → RPC error (bounded by --embed-timeout 2). Next call
        // for a normal text must succeed with the correct vector.
        let script = [
            r#"{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{}}}"#,
            r#"{"jsonrpc":"2.0","method":"notifications/initialized","params":{}}"#,
            r#"{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"remember","arguments":{"content":"will_hang","memory_type":"semantic","text":"HANG"}}}"#,
            r#"{"jsonrpc":"2.0","id":3,"method":"tools/call","params":{"name":"remember","arguments":{"content":"survives","memory_type":"semantic","text":"survives"}}}"#,
        ];
        for line in script {
            writeln!(stdin, "{line}").unwrap();
        }
        drop(child.stdin.take());

        let start = std::time::Instant::now();
        let out = child.wait_with_output().expect("child wait");
        let elapsed = start.elapsed();
        last_stderr = String::from_utf8_lossy(&out.stderr).to_string();
        if out.status.success() {
            assert!(
                elapsed < std::time::Duration::from_secs(30),
                "server should return before 30s even with a HANG; elapsed={elapsed:?}"
            );
            out_opt = Some(out);
            break;
        }
        if !last_stderr.contains("file already locked") {
            panic!(
                "mnemo serve --mcp failed (attempt {attempt}): status={:?} stderr={last_stderr}",
                out.status
            );
        }
    }
    let out = out_opt.unwrap_or_else(|| {
        panic!("mnemo serve --mcp never acquired the lock: stderr={last_stderr}")
    });
    let stdout = String::from_utf8_lossy(&out.stdout);
    // The HANG call should produce an RPC error (id 2).
    assert!(
        stdout.contains("\"id\":2") && (stdout.contains("timed out") || stdout.contains("error")),
        "expected an RPC error on the HANG call id 2, got stdout: {stdout}"
    );
    // The next call (id 3) must have succeeded — server stayed up
    // and the child was respawned.
    assert!(
        stdout.contains("\"id\":3"),
        "expected a response to call id 3 after the HANG; got: {stdout}"
    );
    assert!(
        !stdout
            .lines()
            .any(|l| l.contains("\"id\":3") && l.contains("error")),
        "call id 3 (post-HANG) should have succeeded, not errored: {stdout}"
    );
}