supercode-harness 0.4.6

//! TDD suite for *saving* sessions back out in Claude Code and Codex formats.
//!
//! The GIMP model: one canonical in-memory representation, with importers AND
//! exporters per format. The core correctness property is a **semantic
//! round-trip** — load a real session, save it in the same format, load it
//! again, and get the same conversation back.

use std::path::{Path, PathBuf};

use supercode_harness::session::{Session, SessionFormat};
use supercode_harness::{ChatMessage, Role};

fn fixture(name: &str) -> PathBuf {
    Path::new(env!("CARGO_MANIFEST_DIR"))
        .join("tests/fixtures")
        .join(name)
}

/// Compare two messages for semantic (not byte) equality: role, text content,
/// tool-result linkage, and tool calls (name, id, and *parsed* arguments).
fn msg_eq(a: &ChatMessage, b: &ChatMessage) -> bool {
    if a.role != b.role || a.content != b.content || a.tool_call_id != b.tool_call_id {
        return false;
    }
    let (ca, cb) = (a.tool_calls(), b.tool_calls());
    if ca.len() != cb.len() {
        return false;
    }
    ca.iter().zip(cb).all(|(x, y)| {
        x.id == y.id
            && x.function.name == y.function.name
            && x.function.parsed_arguments().ok() == y.function.parsed_arguments().ok()
    })
}

fn assert_messages_eq(a: &Session, b: &Session) {
    assert_eq!(
        a.messages.len(),
        b.messages.len(),
        "message count changed across round-trip"
    );
    for (i, (x, y)) in a.messages.iter().zip(&b.messages).enumerate() {
        assert!(
            msg_eq(x, y),
            "message {i} differs across round-trip:\n  before: {x:?}\n  after:  {y:?}"
        );
    }
}

fn assert_codex_provenance_is_inert(jsonl: &str) {
    for line in jsonl.lines() {
        let record: serde_json::Value = serde_json::from_str(line).unwrap();
        assert_ne!(
            record.get("type").and_then(serde_json::Value::as_str),
            Some("compacted"),
            "normalized compaction provenance must not execute a second time"
        );
        if record.get("type").and_then(serde_json::Value::as_str) == Some("event_msg") {
            assert!(!matches!(
                record
                    .get("payload")
                    .and_then(|payload| payload.get("type"))
                    .and_then(serde_json::Value::as_str),
                Some("thread_rolled_back")
                    | Some("entered_review_mode")
                    | Some("exited_review_mode")
            ));
        }
    }
}

#[test]
fn claude_code_round_trips() {
    let original = Session::from_claude_code(fixture("claude_code_session.jsonl")).unwrap();
    let jsonl = original.to_jsonl(SessionFormat::ClaudeCode).unwrap();
    let reloaded = Session::from_claude_code_str(&jsonl).unwrap();

    assert_messages_eq(&original, &reloaded);
    assert_eq!(original.meta.session_id, reloaded.meta.session_id);
    assert_eq!(original.meta.model, reloaded.meta.model);
    assert_eq!(original.meta.cwd, reloaded.meta.cwd);
}

#[test]
fn codex_round_trips() {
    let original = Session::from_codex(fixture("codex_session.jsonl")).unwrap();
    let jsonl = original.to_jsonl(SessionFormat::Codex).unwrap();
    let reloaded = Session::from_codex_str(&jsonl).unwrap();

    assert_messages_eq(&original, &reloaded);
    assert_eq!(original.meta.session_id, reloaded.meta.session_id);
    assert_eq!(original.meta.model, reloaded.meta.model);
    assert_eq!(original.meta.cwd, reloaded.meta.cwd);
    // Codex carries the base instructions; they must survive the round-trip.
    assert_eq!(original.meta.system_prompt, reloaded.meta.system_prompt);
}

#[test]
fn saved_output_is_valid_jsonl_for_each_format() {
    let s = Session::from_codex(fixture("codex_session.jsonl")).unwrap();

    let cc = s.to_jsonl(SessionFormat::ClaudeCode).unwrap();
    for line in cc.lines().filter(|l| !l.trim().is_empty()) {
        let v: serde_json::Value = serde_json::from_str(line).expect("CC line must be JSON");
        assert!(v.get("type").is_some(), "CC lines carry a top-level type");
        assert!(
            v.get("payload").is_none(),
            "CC lines have no payload envelope"
        );
    }

    let cx = s.to_jsonl(SessionFormat::Codex).unwrap();
    for line in cx.lines().filter(|l| !l.trim().is_empty()) {
        let v: serde_json::Value = serde_json::from_str(line).expect("Codex line must be JSON");
        assert!(
            v.get("payload").is_some(),
            "Codex lines carry a payload envelope"
        );
    }
}

#[test]
fn cross_format_export_preserves_the_conversation() {
    // GIMP "export as": converting Codex → Claude Code re-materializes a
    // content-bearing developer/system turn as a real Claude `type: "system"`
    // record (PARITY-6 dev/02) rather than dropping it, but this fixture's
    // turn is native Codex framing with no Claude-origin `systemSubtype` to
    // recover, so the record's `subtype` label is only a best-effort guess —
    // this test compares the user/assistant/tool conversation (which must
    // survive byte-for-byte) and leaves that guessed label out of scope.
    let codex = Session::from_codex(fixture("codex_session.jsonl")).unwrap();
    let as_cc = codex.to_jsonl(SessionFormat::ClaudeCode).unwrap();
    let reloaded = Session::from_claude_code_str(&as_cc).unwrap();

    let convo = |s: &Session| -> Vec<ChatMessage> {
        s.messages
            .iter()
            .filter(|m| m.role != Role::System)
            .cloned()
            .collect()
    };
    let before = convo(&codex);
    let after = convo(&reloaded);
    assert_eq!(before.len(), after.len());
    for (x, y) in before.iter().zip(&after) {
        assert!(
            msg_eq(x, y),
            "cross-format conversation differs:\n{x:?}\n{y:?}"
        );
    }
}

#[test]
fn save_writes_a_file() {
    let s = Session::from_claude_code(fixture("claude_code_session.jsonl")).unwrap();
    let out = std::env::temp_dir().join(format!("supercode-save-{}.jsonl", std::process::id()));
    s.save(&out, SessionFormat::ClaudeCode).unwrap();
    let reloaded = Session::load(&out).unwrap();
    assert_messages_eq(&s, &reloaded);
    std::fs::remove_file(&out).ok();
}

// ---- P4: lossless native format + file-history-snapshot retention ---------

#[test]
fn native_format_round_trips_losslessly_inline() {
    // A Claude transcript including a file-history-snapshot, which has no
    // canonical message representation and is dropped by normalization.
    let jsonl = concat!(
        r#"{"type":"user","message":{"role":"user","content":"hi"},"sessionId":"s","cwd":"/tmp"}"#,
        "\n",
        r#"{"type":"file-history-snapshot","messageId":"m1","snapshot":{"files":{"/a.rs":"old"}},"isSnapshotUpdate":false}"#,
        "\n",
        r#"{"type":"assistant","message":{"role":"assistant","content":[{"type":"text","text":"ok"}]},"sessionId":"s"}"#,
    );
    let original = Session::from_claude_code_str(jsonl).unwrap();

    // Normalization drops the snapshot from the conversation…
    assert!(!original.messages.iter().any(|m| m
        .content
        .as_deref()
        .unwrap_or("")
        .contains("snapshot")));
    // …but the raw record is retained.
    assert!(original
        .raw
        .iter()
        .any(|l| l.contains("file-history-snapshot")));

    // Native round-trip is byte-for-byte lossless on the raw lines.
    let native = original.to_native_jsonl();
    let reloaded = Session::from_native_str(&native).unwrap();
    assert_eq!(
        original.raw, reloaded.raw,
        "native round-trip must be lossless"
    );
    assert_eq!(reloaded.meta.source, SessionFormat::ClaudeCode.source());
    // The file-history-snapshot survives the native round-trip.
    assert!(reloaded
        .raw
        .iter()
        .any(|l| l.contains("file-history-snapshot")));
}

/// Corpus proof: real sessions (both formats) round-trip losslessly through the
/// native format — every original line is preserved verbatim.
#[test]
#[ignore = "requires local session corpus; set SUPERCODE_CORPUS=1"]
fn native_format_lossless_over_corpus() {
    if std::env::var("SUPERCODE_CORPUS").is_err() {
        panic!(
            "SUPERCODE_CORPUS not set — this corpus test asserts nothing without \
             the maintainer's local session logs; set SUPERCODE_CORPUS=1 to run it."
        );
    }
    let home = std::env::var("HOME").unwrap();
    let mut checked = 0usize;
    for sub in [".claude/projects", ".codex/sessions"] {
        let dir = PathBuf::from(&home).join(sub);
        for path in jsonl_files(&dir).into_iter().take(300) {
            let Ok(original) = Session::load(&path) else {
                continue;
            };
            if original.raw.is_empty() {
                continue;
            }
            let native = original.to_native_jsonl();
            let reloaded = Session::from_native_str(&native).unwrap();
            assert_eq!(
                original.raw,
                reloaded.raw,
                "{}: native round-trip not lossless",
                path.display()
            );
            checked += 1;
        }
    }
    eprintln!("native lossless round-trip verified on {checked} real sessions");
    assert!(checked > 0);
}

// ---- P4: Codex execution-settings + lineage survive round-trip ------------

#[test]
fn codex_turn_context_and_lineage_survive_round_trip() {
    // A Codex rollout whose header carries execution settings (turn_context) and
    // session lineage (session_meta) that have no slot in the canonical message
    // model. They must survive load -> save -> load because the exporter replays
    // the original header records verbatim.
    let jsonl = r#"{"type":"session_meta","payload":{"id":"sess-1","cwd":"/tmp","originator":"codex_exec","cli_version":"0.141.0","model_provider":"openai","thread_source":"subagent","forked_from_id":"parent-9","source":{"subagent":{"thread_spawn":{"parent_thread_id":"parent-9","depth":2,"agent_role":"worker","agent_nickname":"Euler"}}}}}
{"type":"turn_context","payload":{"model":"gpt-5.5","approval_policy":"never","sandbox_policy":"read-only","effort":"high","personality":"pragmatic","user_instructions":"be terse","collaboration_mode":"solo","workspace_roots":["/tmp"],"truncation_policy":"auto","permission_profile":"default"}}
{"type":"response_item","payload":{"type":"message","role":"user","content":[{"type":"input_text","text":"hello"}]}}"#;

    let original = Session::from_codex(write_temp(jsonl))
        .unwrap_or_else(|_| Session::from_codex_str(jsonl).unwrap());
    let saved = original.to_jsonl(SessionFormat::Codex).unwrap();

    // Every execution setting + lineage key is present verbatim in the export.
    for needle in [
        "\"approval_policy\":\"never\"",
        "\"sandbox_policy\":\"read-only\"",
        "\"effort\":\"high\"",
        "\"personality\":\"pragmatic\"",
        "\"user_instructions\":\"be terse\"",
        "\"collaboration_mode\":\"solo\"",
        "\"truncation_policy\":\"auto\"",
        "\"permission_profile\":\"default\"",
        "\"originator\":\"codex_exec\"",
        "\"cli_version\":\"0.141.0\"",
        "\"forked_from_id\":\"parent-9\"",
        "\"thread_source\":\"subagent\"",
        "\"agent_nickname\":\"Euler\"",
    ] {
        assert!(
            saved.contains(needle),
            "round-trip dropped {needle}\n{saved}"
        );
    }

    // And it still loads, with lineage recovered.
    let reloaded = Session::from_codex_str(&saved).unwrap();
    assert_eq!(reloaded.meta.session_id.as_deref(), Some("sess-1"));
    assert_eq!(reloaded.meta.model.as_deref(), Some("gpt-5.5"));
    assert_eq!(
        reloaded
            .meta
            .lineage
            .get("forked_from_id")
            .map(String::as_str),
        Some("parent-9")
    );
    assert_eq!(
        reloaded
            .meta
            .lineage
            .get("agent_nickname")
            .map(String::as_str),
        Some("Euler")
    );
}

#[test]
fn codex_provenance_survives_disk_reloaded_claude_hop_without_reapplying_events() {
    let original_path = fixture("codex_session_eventmsg.jsonl");
    let original_text = std::fs::read_to_string(&original_path).unwrap();
    let original = Session::from_codex(&original_path).unwrap();
    let source_lines: Vec<&str> = original_text.trim_end_matches('\n').split('\n').collect();
    for kind in [
        "session_meta",
        "turn_context",
        "compacted",
        "event_msg/thread_rolled_back",
        "event_msg/entered_review_mode",
        "event_msg/exited_review_mode",
    ] {
        assert!(
            original.meta.codex_provenance.iter().any(|entry| {
                entry.get("kind").and_then(serde_json::Value::as_str) == Some(kind)
            }),
            "missing captured Codex provenance kind {kind}"
        );
    }
    for entry in &original.meta.codex_provenance {
        let index = entry
            .get("record_index")
            .and_then(serde_json::Value::as_u64)
            .unwrap() as usize;
        let raw = entry
            .get("raw")
            .and_then(serde_json::Value::as_str)
            .unwrap();
        assert_eq!(
            raw, source_lines[index],
            "captured line {index} was normalized"
        );
    }

    let claude_jsonl = original.to_jsonl(SessionFormat::ClaudeCode).unwrap();
    let tmp = std::env::temp_dir().join(format!(
        "supercode-parity13-claude-hop-{}.jsonl",
        std::process::id()
    ));
    std::fs::write(&tmp, &claude_jsonl).unwrap();
    let through_claude = Session::from_claude_code(&tmp).unwrap();
    std::fs::remove_file(&tmp).ok();

    assert_messages_eq(&original, &through_claude);
    assert_eq!(
        through_claude.meta.codex_provenance,
        original.meta.codex_provenance
    );
    assert_eq!(
        through_claude.meta.codex_headers,
        original.meta.codex_headers
    );

    let returned_codex = through_claude.to_jsonl(SessionFormat::Codex).unwrap();
    let mut saw_extension = false;
    for line in returned_codex.lines() {
        let record: serde_json::Value = serde_json::from_str(line).unwrap();
        assert_ne!(
            record.get("type").and_then(serde_json::Value::as_str),
            Some("compacted"),
            "normalized compaction provenance must not execute a second time"
        );
        if record.get("type").and_then(serde_json::Value::as_str) == Some("event_msg") {
            assert!(!matches!(
                record
                    .get("payload")
                    .and_then(|payload| payload.get("type"))
                    .and_then(serde_json::Value::as_str),
                Some("thread_rolled_back")
                    | Some("entered_review_mode")
                    | Some("exited_review_mode")
            ));
        }
        if record.get("type").and_then(serde_json::Value::as_str) == Some("session_meta") {
            saw_extension = record
                .get("payload")
                .and_then(|payload| payload.get("_supercode_codex_provenance"))
                .is_some();
        }
    }
    assert!(
        saw_extension,
        "returned Codex header must carry the provenance envelope"
    );

    let returned_path = std::env::temp_dir().join(format!(
        "supercode-parity13-returned-codex-{}.jsonl",
        std::process::id()
    ));
    std::fs::write(&returned_path, &returned_codex).unwrap();
    let reloaded = Session::from_codex(&returned_path).unwrap();
    std::fs::remove_file(&returned_path).ok();
    assert_messages_eq(&through_claude, &reloaded);
    assert_eq!(
        reloaded.meta.codex_provenance,
        original.meta.codex_provenance
    );
    assert_eq!(reloaded.meta.codex_headers, original.meta.codex_headers);
}

#[test]
fn codex_provenance_envelope_survives_every_foreign_writer() {
    let original = Session::from_codex(fixture("codex_session_eventmsg.jsonl")).unwrap();
    for format in [
        SessionFormat::ClaudeCode,
        SessionFormat::Pi,
        SessionFormat::OpenCode,
        SessionFormat::Grok,
    ] {
        let exported = original.to_jsonl(format).unwrap();
        let reloaded = match format {
            SessionFormat::ClaudeCode => Session::from_claude_code_str(&exported),
            SessionFormat::Pi => Session::from_pi_str(&exported),
            SessionFormat::OpenCode => Session::from_opencode_str(&exported),
            SessionFormat::Grok => Session::from_grok_str(&exported),
            SessionFormat::Codex | SessionFormat::Gemini | SessionFormat::Goose => unreachable!(),
        }
        .unwrap_or_else(|error| panic!("{format:?} reload failed: {error}"));
        assert_eq!(
            reloaded.meta.codex_provenance, original.meta.codex_provenance,
            "{format:?} dropped Codex provenance"
        );
        assert_eq!(
            reloaded.meta.codex_headers, original.meta.codex_headers,
            "{format:?} failed to restore Codex headers"
        );
        let returned_codex = reloaded.to_jsonl(SessionFormat::Codex).unwrap();
        assert_codex_provenance_is_inert(&returned_codex);
        let returned = Session::from_codex_str(&returned_codex)
            .unwrap_or_else(|error| panic!("{format:?} -> Codex reload failed: {error}"));
        assert_messages_eq(&reloaded, &returned);
        assert_eq!(
            returned.meta.codex_provenance, original.meta.codex_provenance,
            "{format:?} -> Codex dropped provenance"
        );
        assert_eq!(
            returned.meta.codex_headers, original.meta.codex_headers,
            "{format:?} -> Codex failed to restore headers"
        );
    }
}

#[test]
fn codex_provenance_capture_preserves_physical_line_whitespace_and_crlf() {
    let first = " \t{\"type\":\"session_meta\",\"payload\":{\"id\":\"s\",\"cwd\":\"/tmp\"}}\t \r";
    let third = "{\"type\":\"turn_context\",\"payload\":{\"model\":\"gpt-5.5\",\"approval_policy\":\"never\"}}  \r";
    let source = format!("{first}\n\r\n{third}\n");
    let session = Session::from_codex_str(&source).unwrap();
    assert_eq!(session.meta.codex_provenance.len(), 2);
    assert_eq!(session.meta.codex_provenance[0]["record_index"], 0);
    assert_eq!(session.meta.codex_provenance[0]["raw"], first);
    assert_eq!(session.meta.codex_provenance[1]["record_index"], 2);
    assert_eq!(session.meta.codex_provenance[1]["raw"], third);

    let claude = session.to_jsonl(SessionFormat::ClaudeCode).unwrap();
    let restored = Session::from_claude_code_str(&claude).unwrap();
    assert_eq!(
        restored.meta.codex_provenance,
        session.meta.codex_provenance
    );
}

#[test]
fn malformed_codex_provenance_envelopes_fail_loudly_and_atomically() {
    let valid = serde_json::json!({
        "record_index": 0,
        "kind": "session_meta",
        "raw": "{\"type\":\"session_meta\",\"payload\":{\"id\":\"s\",\"cwd\":\"/tmp\"}}",
    });
    let invalid_cases = [
        serde_json::json!({"version": 999, "records": [valid.clone()]}),
        serde_json::json!({"version": 1, "records": "not-an-array"}),
        serde_json::json!({"version": 1, "records": []}),
        serde_json::json!({"version": 1, "records": [valid.clone(), {
            "record_index": 1,
            "kind": "compacted",
            "raw": "{\"type\":\"turn_context\",\"payload\":{}}",
        }]}),
        serde_json::json!({"version": 1, "records": [{
            "record_index": 0,
            "kind": "session_meta",
            "raw": "not-json",
        }]}),
        serde_json::json!({"version": 1, "records": [{
            "kind": "session_meta",
            "raw": "{\"type\":\"session_meta\",\"payload\":{}}",
        }]}),
    ];
    for extension in invalid_cases {
        let carrier = serde_json::json!({
            "type": "system",
            "subtype": "local_command",
            "content": "",
            "uuid": "carrier",
            "sessionId": "s",
            "cwd": "/tmp",
            "_supercode_codex_provenance": extension,
        });
        let error = Session::from_claude_code_str(&format!("{carrier}\n"))
            .expect_err("malformed provenance must not silently load");
        assert!(
            error
                .to_string()
                .contains("invalid portable Codex provenance"),
            "unexpected error: {error}"
        );
    }
}

#[test]
fn empty_codex_session_uses_non_conversational_foreign_carriers() {
    let source = "{\"type\":\"session_meta\",\"payload\":{\"id\":\"empty\",\"cwd\":\"/tmp\"}}\n{\"type\":\"turn_context\",\"payload\":{\"model\":\"gpt-5.5\"}}\n";
    let original = Session::from_codex_str(source).unwrap();
    assert!(original.messages.is_empty());
    for format in [
        SessionFormat::ClaudeCode,
        SessionFormat::Pi,
        SessionFormat::OpenCode,
        SessionFormat::Grok,
    ] {
        let exported = original.to_jsonl(format).unwrap();
        let foreign = match format {
            SessionFormat::ClaudeCode => Session::from_claude_code_str(&exported),
            SessionFormat::Pi => Session::from_pi_str(&exported),
            SessionFormat::OpenCode => Session::from_opencode_str(&exported),
            SessionFormat::Grok => Session::from_grok_str(&exported),
            SessionFormat::Codex | SessionFormat::Gemini | SessionFormat::Goose => unreachable!(),
        }
        .unwrap_or_else(|error| panic!("empty {format:?} carrier failed: {error}"));
        assert!(
            foreign.messages.is_empty(),
            "{format:?} carrier became a chat turn"
        );
        assert_eq!(
            foreign.meta.codex_provenance,
            original.meta.codex_provenance
        );
        let returned_codex = foreign.to_jsonl(SessionFormat::Codex).unwrap();
        assert_codex_provenance_is_inert(&returned_codex);
        let returned = Session::from_codex_str(&returned_codex).unwrap();
        assert!(returned.messages.is_empty());
        assert_eq!(
            returned.meta.codex_provenance,
            original.meta.codex_provenance
        );
    }
}

fn write_temp(jsonl: &str) -> std::path::PathBuf {
    let p = std::env::temp_dir().join(format!("sc-p4-{}.jsonl", std::process::id()));
    std::fs::write(&p, jsonl).unwrap();
    p
}

// ---- header fidelity (verified against the real codex binary) -------------
//
// The stock `codex` CLI validates the rollout header strictly ("does not start
// with session metadata"). These guard the two ways we produce that header.

#[test]
fn codex_export_replays_original_header_and_overrides_id() {
    let mut s = Session::from_codex(fixture("codex_session.jsonl")).unwrap();
    assert!(
        !s.meta.codex_headers.is_empty(),
        "header should be captured on load"
    );
    s.meta.session_id = Some("new-id-123".into());

    let jsonl = s.to_jsonl(SessionFormat::Codex).unwrap();
    let first: serde_json::Value = serde_json::from_str(jsonl.lines().next().unwrap()).unwrap();
    assert_eq!(first["type"], "session_meta");
    assert_eq!(
        first["payload"]["id"], "new-id-123",
        "id override must apply"
    );
    // The fields the real codex reader expects are present because we replay
    // the original header verbatim.
    for k in [
        "cwd",
        "model_provider",
        "originator",
        "source",
        "base_instructions",
    ] {
        assert!(
            first["payload"].get(k).is_some(),
            "replayed header missing `{k}`"
        );
    }
}

#[test]
fn synthesized_codex_header_has_required_fields() {
    // A Claude Code source has no codex header to replay, so the writer
    // synthesizes one — it must still carry the fields codex requires.
    let s = Session::from_claude_code(fixture("claude_code_session.jsonl")).unwrap();
    assert!(s.meta.codex_headers.is_empty());

    let jsonl = s.to_jsonl(SessionFormat::Codex).unwrap();
    let first: serde_json::Value = serde_json::from_str(jsonl.lines().next().unwrap()).unwrap();
    assert_eq!(first["type"], "session_meta");
    for k in [
        "id",
        "cwd",
        "originator",
        "cli_version",
        "source",
        "thread_source",
        "model_provider",
    ] {
        assert!(
            first["payload"].get(k).is_some(),
            "synthesized header missing `{k}`"
        );
    }
}

// ---- corpus round-trip (opt-in) -------------------------------------------

#[test]
#[ignore = "requires local session corpus; set SUPERCODE_CORPUS=1"]
fn corpus_round_trips() {
    if std::env::var("SUPERCODE_CORPUS").is_err() {
        panic!(
            "SUPERCODE_CORPUS not set — this corpus test asserts nothing without \
             the maintainer's local session logs; set SUPERCODE_CORPUS=1 to run it."
        );
    }
    let home = std::env::var("HOME").unwrap();
    let cases = [
        (
            PathBuf::from(&home).join(".claude/projects"),
            SessionFormat::ClaudeCode,
            500usize,
        ),
        (
            PathBuf::from(&home).join(".codex/sessions"),
            SessionFormat::Codex,
            500usize,
        ),
    ];

    let mut checked = 0;
    let mut stable = 0;
    for (dir, format, limit) in cases {
        for path in jsonl_files(&dir).into_iter().take(limit) {
            let Ok(original) = Session::load(&path) else {
                continue;
            };
            if original.messages.is_empty() {
                continue;
            }
            checked += 1;
            let jsonl = original.to_jsonl(format).unwrap();
            let reloaded = match Session::load_str(&jsonl, format) {
                Ok(s) => s,
                Err(e) => {
                    eprintln!("re-parse failed {}: {e}", path.display());
                    continue;
                }
            };
            if original.messages.len() == reloaded.messages.len()
                && original
                    .messages
                    .iter()
                    .zip(&reloaded.messages)
                    .all(|(a, b)| msg_eq(a, b))
            {
                stable += 1;
            } else {
                eprintln!("NOT stable: {}", path.display());
            }
        }
    }

    eprintln!("round-trip: checked={checked} stable={stable}");
    assert!(checked > 0);
    // Saving must reproduce the conversation for the overwhelming majority.
    assert!(
        stable as f64 / checked as f64 > 0.97,
        "round-trip unstable: {stable}/{checked}"
    );
}

// ---- PARITY-6/7 (PARITY-AUDIT.md P006/P007, opt-in): real large Claude ----
// ---- sessions must not lose messages converting to Codex ------------------

/// The audit's headline defect: `supercode convert <real Claude session>
/// --to codex` followed by `inspect` showed FEWER messages than the source
/// (`22059 -> 17007`, `17159 -> 15582`). Root-caused to `push_codex_item`'s
/// IX-6 "combined text+tool_use turn" merge wrongly re-folding two
/// ADJACENT-but-genuinely-SEPARATE Claude assistant records (a bare
/// text-only narration line immediately followed by a bare tool-call line,
/// both common in real transcripts) back into one — see
/// `write_codex_records`'s PARITY-6/7 fix (synthetic per-`ChatMessage`
/// `metadata.turn_id`) and the always-on unit-level regression in
/// `roundtrip_regression.rs`. This is the large-real-corpus proof: message
/// count must be preserved EXACTLY across Claude -> Codex for real sessions,
/// not just the small hand-built fixture.
#[test]
#[ignore = "requires local session corpus; set SUPERCODE_CORPUS=1"]
fn claude_to_codex_preserves_message_count_over_corpus() {
    if std::env::var("SUPERCODE_CORPUS").is_err() {
        panic!(
            "SUPERCODE_CORPUS not set — this corpus test asserts nothing without \
             the maintainer's local session logs; set SUPERCODE_CORPUS=1 to run it."
        );
    }
    let home = std::env::var("HOME").unwrap();
    let dir = PathBuf::from(&home).join(".claude/projects");

    // "Large" mirrors the audit's own real samples (tens of thousands of
    // lines) — small/trivial sessions rarely exercise the adjacency shape,
    // so this floor keeps the sample meaningful rather than vacuous.
    const MIN_MESSAGES: usize = 200;
    const MIN_LARGE_SESSIONS: usize = 10;

    // PARITY-11 carve-out: a genuinely reasoning-only turn (`thinking`/
    // `redacted_thinking` metadata, no text/tool_use/image/tool_calls at
    // all) is provider-private and has no Codex wire representation for a
    // standalone occurrence — Claude's own spec text explicitly allows this
    // ("or produce an explicit loss manifest for inherently unrepresentable
    // fields"). `push_claude_assistant`'s PARITY-11 fix stopped these ~21%
    // of real assistant records from vanishing SILENTLY (they're now real,
    // inspectable messages with `metadata["thinking"]`/
    // `metadata["redacted_thinking"]` set), but they were never
    // "replayable" content Codex could carry across the hop in the first
    // place — count PARITY-6/7 fidelity over the REPLAYABLE messages only,
    // matching what `convert`'s own summary line already means by "source
    // messages".
    fn is_reasoning_only(m: &ChatMessage) -> bool {
        m.role == Role::Assistant
            && m.content.is_none()
            && m.content_parts.is_none()
            && m.tool_calls().is_empty()
            && (m.metadata.contains_key("thinking") || m.metadata.contains_key("redacted_thinking"))
    }
    fn replayable_count(messages: &[ChatMessage]) -> usize {
        messages.iter().filter(|m| !is_reasoning_only(m)).count()
    }

    let mut checked_large = 0usize;
    let mut mismatches: Vec<String> = Vec::new();
    for path in jsonl_files(&dir) {
        let Ok(original) = Session::from_claude_code(&path) else {
            continue;
        };
        if original.messages.len() < MIN_MESSAGES {
            continue;
        }
        checked_large += 1;
        let as_codex = original.to_jsonl(SessionFormat::Codex).unwrap();
        let reloaded = Session::from_codex_str(&as_codex).unwrap();
        let (before, after) = (
            replayable_count(&original.messages),
            replayable_count(&reloaded.messages),
        );
        if before != after {
            mismatches.push(format!(
                "{}: {before} -> {after} (raw {} -> {})",
                path.display(),
                original.messages.len(),
                reloaded.messages.len()
            ));
        }
    }

    eprintln!(
        "PARITY-6/7 corpus check: {checked_large} large real Claude sessions (>= \
         {MIN_MESSAGES} messages), {} message-count mismatches",
        mismatches.len()
    );
    assert!(
        checked_large >= MIN_LARGE_SESSIONS,
        "need at least {MIN_LARGE_SESSIONS} large real Claude sessions to prove \
         this at scale (PARITY-6/7 dev/03); only found {checked_large} under {}",
        dir.display()
    );
    assert!(
        mismatches.is_empty(),
        "Claude -> Codex message count changed on {} real session(s):\n{}",
        mismatches.len(),
        mismatches.join("\n")
    );
}

// ---- PARITY-6 dev/02 (Fable-5 skeptic-confirmed, real 2,982-msg session): --
// ---- the REVERSE hop (Claude -> Codex -> Claude) must not lose a real -----
// ---- content-bearing `system` record. --------------------------------------

/// The forward-hop test above (`claude_to_codex_preserves_message_count_over_corpus`)
/// locks ONLY Claude -> Codex. It never guarded the reverse leg of a
/// round-trip: Codex -> Claude Code used to unconditionally drop every
/// `Role::System` `ChatMessage` (`write_claude_code_records`'s old `Role::System
/// => continue`), silently vanishing a real Claude `<local-command-stdout>`
/// system record with no loss manifest (confirmed on a real 2,982-message
/// session: Claude -> Codex correctly preserves `system: 1`, but Codex ->
/// Claude then drops it, `system: 1 -> 0`, `2215 -> 2214`). Fixed by
/// re-materializing a content-bearing `System` message as a real Claude Code
/// `type: "system"` record (the inverse of `push_claude_system`), with the
/// original `subtype` carried losslessly through the Codex hop via
/// `metadata.claude_system_subtype` (`write_codex_records`'s `Role::System`
/// arm / `push_codex_item`'s restore). This is the large-real-corpus proof
/// for the FULL round trip: message count (and specifically the `system`
/// role count) must be preserved EXACTLY across Claude -> Codex -> Claude.
#[test]
#[ignore = "requires local session corpus; set SUPERCODE_CORPUS=1"]
fn claude_to_codex_to_claude_preserves_message_count_over_corpus() {
    if std::env::var("SUPERCODE_CORPUS").is_err() {
        panic!(
            "SUPERCODE_CORPUS not set — this corpus test asserts nothing without \
             the maintainer's local session logs; set SUPERCODE_CORPUS=1 to run it."
        );
    }
    let home = std::env::var("HOME").unwrap();
    let dir = PathBuf::from(&home).join(".claude/projects");

    const MIN_MESSAGES: usize = 200;
    const MIN_LARGE_SESSIONS: usize = 10;

    // Same PARITY-11 carve-out as the forward-hop test: a genuinely
    // reasoning-only assistant turn has no Codex wire representation for a
    // standalone occurrence and is documented, accounted-for `Dropped`
    // coverage, not a message-count regression.
    fn is_reasoning_only(m: &ChatMessage) -> bool {
        m.role == Role::Assistant
            && m.content.is_none()
            && m.content_parts.is_none()
            && m.tool_calls().is_empty()
            && (m.metadata.contains_key("thinking") || m.metadata.contains_key("redacted_thinking"))
    }
    fn replayable_count(messages: &[ChatMessage]) -> usize {
        messages.iter().filter(|m| !is_reasoning_only(m)).count()
    }
    fn system_count(messages: &[ChatMessage]) -> usize {
        messages.iter().filter(|m| m.role == Role::System).count()
    }

    let mut checked_large = 0usize;
    let mut sessions_with_system = 0usize;
    let mut mismatches: Vec<String> = Vec::new();
    for path in jsonl_files(&dir) {
        let Ok(original) = Session::from_claude_code(&path) else {
            continue;
        };
        if original.messages.len() < MIN_MESSAGES {
            continue;
        }
        checked_large += 1;
        let orig_system = system_count(&original.messages);
        if orig_system > 0 {
            sessions_with_system += 1;
        }
        let as_codex = original.to_jsonl(SessionFormat::Codex).unwrap();
        let hop1 = Session::from_codex_str(&as_codex).unwrap();
        let back_to_claude = hop1.to_jsonl(SessionFormat::ClaudeCode).unwrap();
        let hop2 = Session::from_claude_code_str(&back_to_claude).unwrap();

        let (before, after) = (
            replayable_count(&original.messages),
            replayable_count(&hop2.messages),
        );
        let (before_sys, after_sys) = (orig_system, system_count(&hop2.messages));
        if before != after || before_sys != after_sys {
            mismatches.push(format!(
                "{}: total {before} -> {after} (raw {} -> {}), system {before_sys} -> {after_sys}",
                path.display(),
                original.messages.len(),
                hop2.messages.len()
            ));
        }
    }

    eprintln!(
        "PARITY-6 dev/02 reverse-hop corpus check: {checked_large} large real Claude \
         sessions (>= {MIN_MESSAGES} messages), {sessions_with_system} carrying a real \
         system record, {} message-count mismatches",
        mismatches.len()
    );
    assert!(
        checked_large >= MIN_LARGE_SESSIONS,
        "need at least {MIN_LARGE_SESSIONS} large real Claude sessions to prove \
         this at scale; only found {checked_large} under {}",
        dir.display()
    );
    assert!(
        sessions_with_system > 0,
        "need at least one real session with a content-bearing `system` record \
         to exercise the PARITY-6 dev/02 regression at all; found none under {}",
        dir.display()
    );
    assert!(
        mismatches.is_empty(),
        "Claude -> Codex -> Claude message count changed on {} real session(s):\n{}",
        mismatches.len(),
        mismatches.join("\n")
    );
}

// ---- P008/P009 (PARITY-AUDIT.md): `Session::raw_verbatim` reconstructs the
// exact source bytes, including non-message records the semantic view
// writer (`to_jsonl`) has no slot for and would otherwise silently drop. ----

/// The multi-record fixture (`queue-operation`, `last-prompt`, `attachment`,
/// `deferred_tools_delta`, `skill_listing`, alongside `user`/`assistant`)
/// must come back byte-for-byte via `raw_verbatim`, unlike `to_jsonl` which
/// only round-trips the records it canonicalizes.
#[test]
fn raw_verbatim_reproduces_the_source_file_byte_for_byte() {
    let path = fixture("claude_code_session.jsonl");
    let original = std::fs::read_to_string(&path).unwrap();
    let session = Session::from_claude_code_str(&original).unwrap();

    assert_eq!(
        session.raw_verbatim(),
        original,
        "raw_verbatim must reproduce the exact source bytes"
    );

    // The semantic writer, by contrast, is NOT expected to be byte-identical
    // — it drops/re-synthesizes records — so this is a regression guard on
    // the *distinction*, not a claim `to_jsonl` should also match.
    let semantic = session.to_jsonl(SessionFormat::ClaudeCode).unwrap();
    assert_ne!(
        semantic, original,
        "sanity check: the fixture must actually exercise records the semantic \
         writer drops, or this test stops proving anything"
    );
}

/// A source file with NO trailing newline must round-trip with no trailing
/// newline either — `raw_trailing_newline` is exactly the bit that makes
/// this possible (a plain `lines.join("\n")` alone can't distinguish the
/// two cases).
#[test]
fn raw_verbatim_preserves_absence_of_trailing_newline() {
    let no_trailing_newline = "{\"type\":\"user\",\"message\":{\"role\":\"user\",\"content\":\"hi\"},\"uuid\":\"u1\",\"sessionId\":\"s1\"}";
    assert!(!no_trailing_newline.ends_with('\n'));
    let session = Session::from_claude_code_str(no_trailing_newline).unwrap();
    assert_eq!(session.raw_verbatim(), no_trailing_newline);
    assert!(!session.raw_verbatim().ends_with('\n'));
}

/// A source file WITH a trailing newline must keep it.
#[test]
fn raw_verbatim_preserves_presence_of_trailing_newline() {
    let with_trailing_newline = "{\"type\":\"user\",\"message\":{\"role\":\"user\",\"content\":\"hi\"},\"uuid\":\"u1\",\"sessionId\":\"s1\"}\n";
    let session = Session::from_claude_code_str(with_trailing_newline).unwrap();
    assert_eq!(session.raw_verbatim(), with_trailing_newline);
}

// ---- PARITY-10 (docs/audit/PARITY-AUDIT.md P010): `fork-context-ref` ------
//
// No sample of this record was found in ANY locally available real Claude
// corpus (it's vanishingly rare — 5 occurrences in the audit's own
// ~1.3M-record reference corpus) or documented in `docs/interop/`, so this
// is a REAL-FORMAT reconstruction (Claude Code's own field/kebab-case
// conventions: `type`/`uuid`/`parentUuid`/`sessionId`/`cwd`/`timestamp`/
// `version`/`gitBranch`, exactly like every other record in
// `claude_code_session.jsonl`, plus plausible fork-lineage fields modeled on
// Codex's already-real `forked_from_id`), not a real captured sample — see
// the PARITY-10 verdict in the build report for that caveat.
const FORK_CONTEXT_REF_JSONL: &str = r#"{"type":"fork-context-ref","uuid":"f0000000-0000-0000-0000-000000000001","parentUuid":null,"sessionId":"213bb148-51ea-453f-9206-f8b4b1168547","timestamp":"2026-06-07T18:37:59.900Z","cwd":"/tmp/work","forkedFromSessionId":"aaaa1111-2222-3333-4444-555566667777","forkedFromUuid":"eb5f9c61-746d-4e66-ac2e-d40fb0bfdb14","version":"2.1.158","gitBranch":"main"}
{"parentUuid":"f0000000-0000-0000-0000-000000000001","isSidechain":false,"type":"user","message":{"role":"user","content":"continue from the fork"},"uuid":"eb5f9c61-746d-4e66-ac2e-d40fb0bfdb14","timestamp":"2026-06-07T18:38:00.065Z","sessionId":"213bb148-51ea-453f-9206-f8b4b1168547","cwd":"/tmp/work"}
{"parentUuid":"eb5f9c61-746d-4e66-ac2e-d40fb0bfdb14","isSidechain":false,"message":{"model":"claude-opus-4-8","type":"message","role":"assistant","content":[{"type":"text","text":"Sure, continuing from the fork point."}]},"type":"assistant","uuid":"afbe7e88-bd6f-483b-b679-76b76c0c286d","timestamp":"2026-06-07T18:38:06.929Z","sessionId":"213bb148-51ea-453f-9206-f8b4b1168547","cwd":"/tmp/work"}
"#;

/// dev/02: the record survives the SEMANTIC Claude Code writer (not just the
/// CLI's raw-passthrough diagonal, which is proven separately at
/// `crates/cli/tests/convert_surface_cli.rs`'s
/// `diagonal_claude_to_claude_is_byte_identical`-style tests) — loading and
/// re-serializing must not silently drop it.
#[test]
fn fork_context_ref_survives_claude_semantic_diagonal() {
    let original = Session::from_claude_code_str(FORK_CONTEXT_REF_JSONL).unwrap();
    let captured = original
        .meta
        .lineage
        .get("claude_fork_context_ref_raw")
        .expect("fork-context-ref must be captured into lineage on load");

    // D4 (Fable-5 review, confirmed): this used to only be checkable
    // STRUCTURALLY, because `capture_claude_meta` stored `Value::to_string()`
    // — a re-serialization through a key-order-losing `serde_json::Value`
    // (no `preserve_order` feature; see `Cargo.toml`), not the original
    // source text. The PARITY-10 doc comments on `capture_claude_meta` and
    // `to_claude_code_jsonl` both claimed "byte-for-byte" re-emission, which
    // was false: `FORK_CONTEXT_REF_JSONL`'s first line has deliberately
    // non-alphabetical key order (`type,uuid,parentUuid,sessionId,timestamp,
    // cwd,forkedFromSessionId,forkedFromUuid,version,gitBranch`), so the old
    // `v.to_string()` capture would alphabetize it
    // (`cwd,forkedFromSessionId,...,type,uuid,version`) — silently NOT
    // byte-for-byte. Now that the loader stores the raw source line itself,
    // this is genuinely byte-identical. Fails against the pre-fix code
    // (which reordered the keys).
    let original_line = FORK_CONTEXT_REF_JSONL.lines().next().unwrap();
    assert_eq!(
        captured, original_line,
        "fork-context-ref must be captured BYTE-FOR-BYTE (including source \
         field order) into lineage on load, not merely structurally"
    );

    let saved = original.to_jsonl(SessionFormat::ClaudeCode).unwrap();
    assert!(
        saved.contains("\"type\":\"fork-context-ref\"")
            && saved.contains("\"forkedFromSessionId\":\"aaaa1111-2222-3333-4444-555566667777\""),
        "the semantic Claude Code writer must re-emit the captured record: {saved}"
    );
    // The re-emitted line itself is the byte-identical original line (not
    // just a value-equivalent re-serialization).
    assert!(
        saved.lines().any(|l| l == original_line),
        "the semantic Claude Code writer must re-emit the ORIGINAL line \
         byte-for-byte, not a re-serialized (key-reordered) equivalent:\n{saved}"
    );

    let reloaded = Session::from_claude_code_str(&saved).unwrap();
    assert_eq!(
        reloaded
            .meta
            .lineage
            .get("claude_fork_context_ref_raw")
            .map(String::as_str),
        Some(original_line),
        "round-trip through the semantic writer must reproduce the exact \
         original line byte-for-byte"
    );
    // The actual conversation is untouched — the fork marker is metadata,
    // not a conversational turn.
    assert_eq!(original.messages.len(), reloaded.messages.len());
}

/// dev/03: cross-format exports retain enough lineage metadata to
/// reconstruct fork provenance when converting back to Claude — a Claude ->
/// Codex -> Claude round trip must not silently lose the record just
/// because Codex's own on-disk format has no native slot for it.
#[test]
fn fork_context_ref_survives_claude_to_codex_to_claude_round_trip() {
    let original = Session::from_claude_code_str(FORK_CONTEXT_REF_JSONL).unwrap();

    let as_codex = original.to_jsonl(SessionFormat::Codex).unwrap();
    assert!(
        as_codex.contains("\"claude_fork_context_ref\""),
        "the Codex hop must carry the fork lineage as a namespaced passthrough \
         field in the synthesized session_meta header: {as_codex}"
    );

    let via_codex = Session::from_codex_str(&as_codex).unwrap();
    // Structural, not byte-for-byte: unlike the native Claude Code diagonal
    // (`fork_context_ref_survives_claude_semantic_diagonal`, D4-fixed to
    // reuse the ORIGINAL source line verbatim), the Codex hop necessarily
    // re-serializes through a `serde_json::Value` embed/parse cycle to sit
    // inside `session_meta.payload.claude_fork_context_ref` — this crate
    // doesn't enable `preserve_order`, so that hop alphabetizes keys. This
    // was always documented as "reconstructs the original record"
    // (`capture_codex_session_meta`'s dev/03 comment), never claimed
    // byte-for-byte, so compare parsed values here rather than raw strings.
    let via_codex_raw = via_codex
        .meta
        .lineage
        .get("claude_fork_context_ref_raw")
        .expect("the Codex loader must restore the fork lineage from the passthrough field");
    let original_raw = original
        .meta
        .lineage
        .get("claude_fork_context_ref_raw")
        .unwrap();
    assert_eq!(
        serde_json::from_str::<serde_json::Value>(via_codex_raw).unwrap(),
        serde_json::from_str::<serde_json::Value>(original_raw).unwrap(),
        "the Codex loader must restore the fork lineage from the passthrough field \
         (structurally — field set and values, not source key order)"
    );

    let back_to_claude = via_codex.to_jsonl(SessionFormat::ClaudeCode).unwrap();
    assert!(
        back_to_claude.contains("\"type\":\"fork-context-ref\"")
            && back_to_claude
                .contains("\"forkedFromSessionId\":\"aaaa1111-2222-3333-4444-555566667777\""),
        "converting back to Claude Code must reconstruct the original \
         fork-context-ref record: {back_to_claude}"
    );
}

/// D7 (Fable-5 review, confirmed): fork lineage passthrough
/// (`claude_fork_context_ref` / `claude_fork_context_ref_raw`) used to be
/// carried on the Codex hop ONLY (`write_synthesized_codex_header`/
/// `capture_codex_session_meta`) — a Claude -> Pi -> Claude round trip
/// silently lost it, even though dev/03 documents this as a general
/// "cross-format" guarantee, not a Codex-specific one. Mirrors
/// `fork_context_ref_survives_claude_to_codex_to_claude_round_trip` exactly,
/// swapping the Codex hop for a Pi hop. Fails against the pre-fix
/// `push_pi_header`/`capture_pi_header` (neither read nor wrote
/// `claude_fork_context_ref` at all).
#[test]
fn fork_context_ref_survives_claude_to_pi_to_claude_round_trip() {
    let original = Session::from_claude_code_str(FORK_CONTEXT_REF_JSONL).unwrap();

    let as_pi = original.to_jsonl(SessionFormat::Pi).unwrap();
    assert!(
        as_pi.contains("\"claude_fork_context_ref\""),
        "the Pi hop must carry the fork lineage as a namespaced passthrough \
         field on the session header: {as_pi}"
    );

    let via_pi = Session::from_pi_str(&as_pi).unwrap();
    let via_pi_raw = via_pi
        .meta
        .lineage
        .get("claude_fork_context_ref_raw")
        .expect("the Pi loader must restore the fork lineage from the passthrough field");
    let original_raw = original
        .meta
        .lineage
        .get("claude_fork_context_ref_raw")
        .unwrap();
    assert_eq!(
        serde_json::from_str::<serde_json::Value>(via_pi_raw).unwrap(),
        serde_json::from_str::<serde_json::Value>(original_raw).unwrap(),
        "the Pi loader must restore the fork lineage from the passthrough field \
         (structurally — field set and values, not source key order)"
    );

    let back_to_claude = via_pi.to_jsonl(SessionFormat::ClaudeCode).unwrap();
    assert!(
        back_to_claude.contains("\"type\":\"fork-context-ref\"")
            && back_to_claude
                .contains("\"forkedFromSessionId\":\"aaaa1111-2222-3333-4444-555566667777\""),
        "converting back to Claude Code must reconstruct the original \
         fork-context-ref record: {back_to_claude}"
    );
}

/// D7, OpenCode hop: same guarantee, via `synthesized_opencode_info`/
/// `capture_opencode_session_info`.
#[test]
fn fork_context_ref_survives_claude_to_opencode_to_claude_round_trip() {
    let original = Session::from_claude_code_str(FORK_CONTEXT_REF_JSONL).unwrap();

    let as_opencode = original.to_jsonl(SessionFormat::OpenCode).unwrap();
    assert!(
        as_opencode.contains("claude_fork_context_ref"),
        "the OpenCode hop must carry the fork lineage as a namespaced passthrough \
         field on SessionInfo: {as_opencode}"
    );

    let via_opencode = Session::from_opencode_str(&as_opencode).unwrap();
    let via_opencode_raw = via_opencode
        .meta
        .lineage
        .get("claude_fork_context_ref_raw")
        .expect("the OpenCode loader must restore the fork lineage from the passthrough field");
    let original_raw = original
        .meta
        .lineage
        .get("claude_fork_context_ref_raw")
        .unwrap();
    assert_eq!(
        serde_json::from_str::<serde_json::Value>(via_opencode_raw).unwrap(),
        serde_json::from_str::<serde_json::Value>(original_raw).unwrap(),
        "the OpenCode loader must restore the fork lineage from the passthrough field \
         (structurally — field set and values, not source key order)"
    );

    let back_to_claude = via_opencode.to_jsonl(SessionFormat::ClaudeCode).unwrap();
    assert!(
        back_to_claude.contains("\"type\":\"fork-context-ref\"")
            && back_to_claude
                .contains("\"forkedFromSessionId\":\"aaaa1111-2222-3333-4444-555566667777\""),
        "converting back to Claude Code must reconstruct the original \
         fork-context-ref record: {back_to_claude}"
    );
}

fn jsonl_files(dir: &Path) -> Vec<PathBuf> {
    let mut out = Vec::new();
    let walker = ignore::WalkBuilder::new(dir)
        .standard_filters(false)
        .build();
    for entry in walker.flatten() {
        let p = entry.into_path();
        if p.extension().and_then(|e| e.to_str()) == Some("jsonl") {
            out.push(p);
        }
    }
    out
}