"""Filesystem bridge + tmux injection for the cursor-native terminal harness.

The runner launches the ``cursor-agent`` TUI in a private tmux pane and records
that pane's socket + target here via :func:`write_tmux_target`. The harness
executor then delivers Omnigent web-UI messages into the *same* pane via
:func:`inject_user_message` (tmux bracketed paste + Enter) — the cursor analog
of claude-native's tmux send-keys bridge. This is what wires the web-UI chat box
to the running Cursor TUI (and, since the web UI embeds that pane, the message
shows in both surfaces).
"""

from __future__ import annotations

import contextlib
import hashlib
import json
import os
import secrets
import subprocess
import sys
import tempfile
import time
from pathlib import Path
from typing import Any

from omnigent._platform import stable_user_id

#: Env var carrying the bridge dir into the harness executor process.
BRIDGE_DIR_ENV_VAR = "HARNESS_CURSOR_NATIVE_BRIDGE_DIR"

_BRIDGE_ROOT = Path(tempfile.gettempdir()) / f"omnigent-{stable_user_id()}" / "cursor-native"
_TMUX_FILE = "tmux.json"
_BRIDGE_CONFIG_FILE = "bridge.json"
_MCP_CONFIG_FILE = "mcp.json"
_HOOKS_CONFIG_FILE = "hooks.json"
_MCP_SERVER_NAME = "omnigent"
_CURSOR_AUTO_APPROVE_TOOLS = [
    "list_comments",
    "sys_add_policy",
    "sys_agent_download",
    "sys_agent_get",
    "sys_agent_list",
    "sys_call_async",
    "sys_cancel_async",
    "sys_cancel_task",
    "sys_list_models",
    "sys_os_edit",
    "sys_os_read",
    "sys_os_shell",
    "sys_os_write",
    "sys_policy_registry",
    "sys_session_close",
    "sys_session_create",
    "sys_session_get_history",
    "sys_session_get_info",
    "sys_session_list",
    "sys_session_send",
    "sys_terminal_close",
    "sys_terminal_launch",
    "sys_terminal_list",
    "sys_terminal_read",
    "sys_terminal_send",
    "update_comment",
]
_TMUX_READY_TIMEOUT_S = 30.0
_TMUX_SEND_TIMEOUT_S = 10.0
_POLL_INTERVAL_S = 0.2
_PASTE_SETTLE_S = 0.3
_PASTE_BUFFER = "omnigent-cursor-paste"
# How long to wait for the pasted text to become visible in the pane before
# sending Enter — submitting before the TUI commits the paste folds the Enter
# into the paste as a newline and the message sits unsent.
_PASTE_COMMIT_TIMEOUT_S = 5.0
# Pause between the ``/model`` filter landing and Enter. cursor-agent's
# composer debounces input (~1.5s); an Enter fired too soon selects a stale
# picker highlight. See the cursor-native e2e_ui TUI-driving notes.
_MODEL_PICKER_SETTLE_S = 1.5
# ``/model`` picker filter-result markers. cursor prints ``Models matching
# "<query>"`` above the matched rows, or ``No matches`` when the id resolves to
# nothing. These distinguish a landed filter from the echoed ``/model <id>``
# composer text (which always contains the id), so the readiness gate verifies
# the picker actually matched rather than passing instantly off the echo.
_PICKER_MATCH_MARKER = "Models matching"
_PICKER_NO_MATCH_MARKER = "No matches"
# cursor-agent TUI markers (Phase 0): idle input placeholder / running footer /
# first-run trust modal.
_IDLE_MARKERS = ("Plan, search, build", "Add a follow-up")
_TRUST_MARKER = "Trust this workspace"
# Composer-clear (see _clear_composer): cursor-agent's input widget ignores the
# readline Home/kill-line keys, so we delete with a Backspace flood instead.
# Backspaces per round (one ``send-keys -N`` call) and a round cap; the loop
# stops early once the pane stops changing (the draft is gone). The cap bounds a
# pathological never-settles pane; ``_COMPOSER_CLEAR_CHUNK * _COMPOSER_CLEAR_MAX_ROUNDS``
# deletions comfortably exceed any real draft.
_COMPOSER_CLEAR_CHUNK = 200
_COMPOSER_CLEAR_MAX_ROUNDS = 50
# After a cancel, cursor-agent restores the interrupted prompt into the composer
# slightly after the turn stops. Wait for the pane to stop changing (generation
# ended and the draft settled) before clearing it, bounded by this timeout.
_INTERRUPT_SETTLE_TIMEOUT_S = 2.0


def bridge_dir_for_session_id(session_id: str) -> Path:
    """Return the per-session bridge dir, e.g. ``/tmp/omnigent-<uid>/cursor-native/<hash>``."""
    digest = hashlib.sha256(session_id.encode("utf-8")).hexdigest()[:32]
    return _BRIDGE_ROOT / digest


def bridge_root() -> Path:
    """Return the configured Cursor-native bridge root."""
    return _BRIDGE_ROOT


def _ensure_dir(path: Path) -> None:
    """Create *path* (and parents) with owner-only permissions."""
    path.mkdir(parents=True, exist_ok=True)
    with contextlib.suppress(OSError):
        os.chmod(path, 0o700)


#: File the runner drops into a fork's bridge dir holding the prior-conversation
#: text preamble, consumed once by the executor on the first injected message.
#: cursor's conversation is server-backed (a synthesized local store.db is NOT
#: loaded by ``cursor-agent --resume``), so a fork carries history by replaying
#: the prior turns as a text prefix on the first message (text-prefix replay).
_FORK_PREAMBLE_FILE = "fork_preamble.txt"
#: Sentinel framing the replayed history inside the first injected message. The
#: cursor agent reads the wrapped context, but the forwarder strips this block
#: when mirroring the user turn back to Omnigent so the copied history isn't
#: duplicated in the timeline (see cursor_native_forwarder._unwrap_user_query).
FORK_HISTORY_OPEN_TAG = "<omnigent_fork_history>"
FORK_HISTORY_CLOSE_TAG = "</omnigent_fork_history>"


def write_fork_preamble(bridge_dir: Path, preamble: str) -> None:
    """Persist a fork's prior-conversation preamble for the executor to consume.

    :param bridge_dir: The session's cursor-native bridge dir.
    :param preamble: Rendered prior-conversation text (``""`` is not written).
    """
    if not preamble:
        return
    _ensure_dir(bridge_dir)
    (bridge_dir / _FORK_PREAMBLE_FILE).write_text(preamble, encoding="utf-8")


def read_fork_preamble(bridge_dir: Path) -> str | None:
    """Read the fork preamble WITHOUT consuming it (else ``None``).

    Read and clear are deliberately split: the executor reads the preamble,
    injects it, and only calls :func:`clear_fork_preamble` on a SUCCESSFUL
    injection. Consuming on read would lose the forked history permanently if
    the first injection fails (e.g. the TUI exited) and the turn is retried.

    :param bridge_dir: The session's cursor-native bridge dir.
    :returns: The preamble text, or ``None`` when absent/empty.
    """
    try:
        text = (bridge_dir / _FORK_PREAMBLE_FILE).read_text(encoding="utf-8")
    except (OSError, ValueError):
        return None
    return text or None


def clear_fork_preamble(bridge_dir: Path) -> None:
    """Remove the fork preamble so it rides only the FIRST injected message.

    Called by the executor only after a turn's injection succeeds; subsequent
    turns then inject the plain user text. A no-op when the file is absent.

    :param bridge_dir: The session's cursor-native bridge dir.
    """
    with contextlib.suppress(OSError):
        (bridge_dir / _FORK_PREAMBLE_FILE).unlink()


#: Human-readable lead-in / sign-off framing the replayed transcript inside the
#: sentinel, so the block reads as a contained "here's the prior conversation"
#: note rather than a raw dump. The cursor agent sees this context; the forwarder
#: strips the whole sentinel block from the mirrored web bubble.
_FORK_HISTORY_HEADER = "This session was forked. Here is the conversation so far:"
_FORK_HISTORY_FOOTER = "(End of prior conversation. Please continue from here.)"


def _neutralize_fork_sentinels(text: str) -> str:
    """Defang any literal fork sentinel tags inside replayed transcript text.

    The preamble is rendered from prior user/assistant turns verbatim, so a turn
    could literally contain ``<omnigent_fork_history>`` /
    ``</omnigent_fork_history>`` (a user typed it, pasted logs, etc.). If left
    intact, an embedded close tag would let the forwarder's strip stop early and
    leak the rest of the transcript into the mirrored web bubble. Replacing the
    angle brackets guarantees the framed block contains exactly ONE real
    open/close pair, so the (non-greedy) strip is unambiguous. The bracketed form
    stays readable for the cursor agent.

    :param text: Rendered transcript text.
    :returns: The text with any literal sentinel tags defanged.
    """
    return text.replace(FORK_HISTORY_OPEN_TAG, "[omnigent_fork_history]").replace(
        FORK_HISTORY_CLOSE_TAG, "[/omnigent_fork_history]"
    )


def wrap_fork_preamble(preamble: str, user_text: str) -> str:
    """Combine a fork preamble with the latest user text for one injection.

    The transcript is framed by a human lead-in / sign-off and fenced in
    :data:`FORK_HISTORY_OPEN_TAG` / :data:`FORK_HISTORY_CLOSE_TAG`. cursor can't
    reconstruct native chat bubbles from a fork (its conversation is
    server-backed), so this is the closest single-message analog: the agent
    reads the framed transcript as context, and the forwarder strips the whole
    sentinel block from the mirrored user turn so the copied history isn't
    duplicated in the Omnigent timeline.

    Any literal sentinel tags inside *preamble* are defanged
    (:func:`_neutralize_fork_sentinels`) so the framed block holds exactly one
    real open/close pair — this keeps the forwarder's non-greedy strip
    unambiguous and prevents embedded tags from leaking history. *user_text* is
    left untouched (it sits after the close tag; the non-greedy strip stops at
    the real close, so a tag in the user's own message is preserved).

    :param preamble: Rendered prior-conversation transcript.
    :param user_text: The user's first message in the fork.
    :returns: The framed, fenced transcript followed by the user text.
    """
    return (
        f"{FORK_HISTORY_OPEN_TAG}\n"
        f"{_FORK_HISTORY_HEADER}\n\n"
        f"{_neutralize_fork_sentinels(preamble)}\n\n"
        f"{_FORK_HISTORY_FOOTER}\n"
        f"{FORK_HISTORY_CLOSE_TAG}\n\n"
        f"{user_text}"
    )


def build_cursor_native_spawn_env(session_id: str) -> dict[str, str]:
    """Build the ``HARNESS_CURSOR_NATIVE_*`` env the harness executor reads."""
    bridge_dir = bridge_dir_for_session_id(session_id)
    _ensure_dir(bridge_dir)
    return {
        BRIDGE_DIR_ENV_VAR: str(bridge_dir),
    }


def build_mcp_config(
    bridge_dir: Path,
    *,
    python_executable: str | None = None,
) -> dict[str, Any]:
    """Build Cursor's ``.cursor/mcp.json`` for the Omnigent relay server.

    Cursor prompts for MCP tool approval before it sends ``tools/call`` to the
    server. Omnigent tools already route through the Omnigent ``/mcp`` proxy,
    where TOOL_CALL policies publish ``response.elicitation_request`` events
    that the web UI can render. Auto-approving the Cursor-side MCP gate avoids a
    hidden in-terminal approval prompt blocking the call before Omnigent ever
    sees it, while preserving Omnigent's own policy/elicitation gate.
    """
    python = python_executable or sys.executable
    return {
        "mcpServers": {
            _MCP_SERVER_NAME: {
                "command": python,
                "args": [
                    "-I",
                    "-m",
                    "omnigent.claude_native_bridge",
                    "serve-mcp",
                    "--bridge-dir",
                    str(bridge_dir),
                ],
                "autoApprove": list(_CURSOR_AUTO_APPROVE_TOOLS),
                "env": {
                    "TMPDIR": os.environ.get("TMPDIR", "/tmp"),
                },
            }
        }
    }


def write_mcp_bridge_config(bridge_dir: Path) -> None:
    """Write the token config required by the shared Omnigent MCP bridge."""
    _ensure_dir(bridge_dir)
    config_path = bridge_dir / _BRIDGE_CONFIG_FILE
    if config_path.exists():
        return
    payload = {"token": secrets.token_urlsafe(32)}
    tmp = bridge_dir / (_BRIDGE_CONFIG_FILE + ".tmp")
    tmp.write_text(json.dumps(payload, sort_keys=True) + "\n", encoding="utf-8")
    os.replace(tmp, config_path)


def write_mcp_config(
    workspace: Path,
    bridge_dir: Path,
    *,
    python_executable: str | None = None,
) -> Path:
    """Write the workspace-scoped Cursor MCP config for Omnigent tools."""
    write_mcp_bridge_config(bridge_dir)
    cursor_dir = workspace / ".cursor"
    cursor_dir.mkdir(parents=True, exist_ok=True)
    path = cursor_dir / _MCP_CONFIG_FILE
    payload = build_mcp_config(bridge_dir, python_executable=python_executable)
    tmp = path.with_suffix(path.suffix + ".tmp")
    tmp.write_text(json.dumps(payload, indent=2, sort_keys=True) + "\n", encoding="utf-8")
    os.replace(tmp, path)
    enable_mcp_for_workspace(workspace)
    allow_mcp_tools_in_cli_config()
    return path


def build_hooks_config(
    bridge_dir: Path, *, python_executable: str | None = None
) -> dict[str, Any]:
    """Build Cursor's ``.cursor/hooks.json`` registering the usage ``stop`` hook.

    cursor-agent fires the ``stop`` hook once per completed turn with a JSON
    payload (on stdin) carrying that turn's token usage — the only surface where
    the interactive TUI exposes usage. The hook command runs
    ``omnigent.cursor_native_usage record-usage``, which appends the usage to
    ``<bridge_dir>/cursor_usage.jsonl`` for the runner's usage forwarder to tail
    and post as ``external_session_usage`` (lighting up the web Session-cost
    badge). Bakes the absolute ``--bridge-dir`` so the recorder writes where the
    forwarder reads, regardless of the hook's working directory.
    """
    import shlex

    python = python_executable or sys.executable
    command = " ".join(
        shlex.quote(part)
        for part in (
            python,
            "-I",
            "-m",
            "omnigent.cursor_native_usage",
            "record-usage",
            "--bridge-dir",
            str(bridge_dir),
        )
    )
    return {"version": 1, "hooks": {"stop": [{"command": command}]}}


def write_hooks_config(
    workspace: Path,
    bridge_dir: Path,
    *,
    python_executable: str | None = None,
) -> Path:
    """Write the workspace-scoped Cursor ``hooks.json`` capturing per-turn usage.

    Sibling of :func:`write_mcp_config`: project-scoped Cursor config the TUI
    loads on launch in a trusted workspace. Returns the written path.
    """
    cursor_dir = workspace / ".cursor"
    cursor_dir.mkdir(parents=True, exist_ok=True)
    path = cursor_dir / _HOOKS_CONFIG_FILE
    payload = build_hooks_config(bridge_dir, python_executable=python_executable)
    tmp = path.with_suffix(path.suffix + ".tmp")
    tmp.write_text(json.dumps(payload, indent=2, sort_keys=True) + "\n", encoding="utf-8")
    os.replace(tmp, path)
    return path


def approve_mcp_server_for_workspace(workspace: Path) -> None:
    """Approve the workspace-scoped Omnigent MCP server in Cursor's state.

    Cursor stores per-workspace MCP approvals using a private hash of the
    concrete server config. Rather than duplicate that implementation here,
    ask ``cursor-agent mcp enable omnigent`` to write the exact approval entry
    for this workspace. This is best-effort: the TUI still launches if the
    installed Cursor CLI cannot run the management subcommand, but when it can,
    the hidden server-approval gate is cleared before startup.
    """
    try:
        from omnigent.cursor_native import resolve_cursor_executable

        cursor = resolve_cursor_executable()
        subprocess.run(
            [cursor, "mcp", "enable", _MCP_SERVER_NAME],
            cwd=workspace,
            stdin=subprocess.DEVNULL,
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL,
            timeout=15,
            check=False,
        )
    except (OSError, subprocess.SubprocessError):
        return


def cursor_project_key(workspace: Path) -> str:
    """Return Cursor's project-state directory key for *workspace*."""
    return str(workspace).strip("/").replace("/", "-") or "root"


def enable_mcp_for_workspace(workspace: Path) -> None:
    """Ensure Cursor does not keep the Omnigent MCP disabled for this workspace."""
    disabled_path = (
        Path.home() / ".cursor" / "projects" / cursor_project_key(workspace) / "mcp-disabled.json"
    )
    try:
        raw = json.loads(disabled_path.read_text(encoding="utf-8"))
    except (OSError, ValueError):
        return
    if not isinstance(raw, list) or _MCP_SERVER_NAME not in raw:
        return
    updated = [item for item in raw if item != _MCP_SERVER_NAME]
    tmp = disabled_path.with_suffix(disabled_path.suffix + ".tmp")
    tmp.write_text(json.dumps(updated, indent=2) + "\n", encoding="utf-8")
    os.replace(tmp, disabled_path)


def allow_mcp_tools_in_cli_config() -> None:
    """Allow Omnigent MCP tool calls in Cursor's CLI permission config."""
    path = Path.home() / ".cursor" / "cli-config.json"
    try:
        config = json.loads(path.read_text(encoding="utf-8"))
    except (OSError, ValueError):
        return
    if not isinstance(config, dict):
        return
    permissions = config.setdefault("permissions", {})
    if not isinstance(permissions, dict):
        return
    allow = permissions.setdefault("allow", [])
    if not isinstance(allow, list):
        return
    existing = {item for item in allow if isinstance(item, str)}
    for tool_name in _CURSOR_AUTO_APPROVE_TOOLS:
        entry = f"Mcp({_MCP_SERVER_NAME}:{tool_name})"
        if entry not in existing:
            allow.append(entry)
            existing.add(entry)
    tmp = path.with_suffix(path.suffix + ".tmp")
    tmp.write_text(json.dumps(config, indent=2) + "\n", encoding="utf-8")
    os.replace(tmp, path)


def write_tmux_target(
    bridge_dir: Path,
    *,
    socket_path: Path,
    tmux_target: str,
    pid: int | None = None,
) -> None:
    """Advertise the tmux socket + target for the running Cursor terminal."""
    _ensure_dir(bridge_dir)
    payload: dict[str, Any] = {
        "socket_path": str(socket_path),
        "tmux_target": tmux_target,
        "updated_at": time.time(),
    }
    if pid is not None:
        payload["pid"] = pid
    tmp = bridge_dir / (_TMUX_FILE + ".tmp")
    tmp.write_text(json.dumps(payload), encoding="utf-8")
    os.replace(tmp, bridge_dir / _TMUX_FILE)


def read_tmux_info(bridge_dir: Path) -> dict[str, str] | None:
    """Return ``{socket_path, tmux_target}`` from ``tmux.json``, or ``None``."""
    try:
        raw = (bridge_dir / _TMUX_FILE).read_text(encoding="utf-8")
    except OSError:
        return None
    try:
        data = json.loads(raw)
    except ValueError:
        return None
    socket_path = data.get("socket_path")
    tmux_target = data.get("tmux_target")
    if (
        isinstance(socket_path, str)
        and socket_path
        and isinstance(tmux_target, str)
        and tmux_target
    ):
        return {"socket_path": socket_path, "tmux_target": tmux_target}
    return None


def _wait_for_tmux_info(bridge_dir: Path, *, timeout_s: float) -> dict[str, str]:
    """Block until ``tmux.json`` is advertised, or raise on timeout."""
    deadline = time.monotonic() + timeout_s
    while time.monotonic() < deadline:
        info = read_tmux_info(bridge_dir)
        if info is not None:
            return info
        time.sleep(_POLL_INTERVAL_S)
    raise RuntimeError(f"cursor-native tmux target was not advertised within {timeout_s:.0f}s")


def _run_tmux(socket_path: str, *args: str) -> None:
    """Invoke ``tmux -S <socket> <args...>`` and raise on failure."""
    try:
        proc = subprocess.run(
            ["tmux", "-S", socket_path, *args],
            check=False,
            capture_output=True,
            text=True,
            timeout=_TMUX_SEND_TIMEOUT_S,
        )
    except subprocess.TimeoutExpired as exc:
        raise RuntimeError(f"tmux command timed out after {_TMUX_SEND_TIMEOUT_S}s") from exc
    if proc.returncode != 0:
        detail = proc.stderr.strip() or proc.stdout.strip() or "<no output>"
        raise RuntimeError(f"tmux command failed (rc={proc.returncode}): {detail}")


def _capture_pane(socket_path: str, tmux_target: str) -> str:
    """Capture the visible pane contents; ``""`` on any failure (treat as not-ready)."""
    try:
        proc = subprocess.run(
            ["tmux", "-S", socket_path, "capture-pane", "-p", "-t", tmux_target],
            check=False,
            capture_output=True,
            text=True,
            timeout=_TMUX_SEND_TIMEOUT_S,
        )
    except (subprocess.TimeoutExpired, OSError):
        return ""
    return proc.stdout if proc.returncode == 0 else ""


def _paste_payload_bytes(text: str) -> bytes:
    r"""Encode text for ``tmux load-buffer``: line breaks → CR, tabs kept, other
    control bytes dropped (a stray ESC would close the bracketed-paste early)."""
    normalized = text.replace("\r\n", "\n").replace("\r", "\n")
    body = bytearray()
    for ch in normalized:
        if ch == "\n":
            body.append(0x0D)
            continue
        if ch == "\t":
            body.append(0x09)
            continue
        if ord(ch) < 0x20:
            continue
        body.extend(ch.encode("utf-8"))
    return bytes(body)


def _session_alive(socket_path: str, tmux_target: str) -> bool:
    """Return whether the tmux session/pane still exists (the TUI is running)."""
    try:
        proc = subprocess.run(
            ["tmux", "-S", socket_path, "has-session", "-t", tmux_target],
            check=False,
            capture_output=True,
            text=True,
            timeout=_TMUX_SEND_TIMEOUT_S,
        )
    except (subprocess.TimeoutExpired, OSError):
        return False
    return proc.returncode == 0


def capture_cursor_pane(bridge_dir: Path) -> str | None:
    """
    Return the visible Cursor pane text, or ``None`` if the TUI is not running.

    Reused by the runner-side approval mirror
    (:mod:`omnigent.cursor_native_permissions`) to detect cursor-agent's native
    tool-approval prompts. ``None`` (no advertised tmux target, or a dead pane)
    is distinct from ``""`` (a live but empty capture) so the caller can skip
    polling a TUI that has not started yet or has exited.

    :param bridge_dir: The cursor-native bridge dir holding ``tmux.json``.
    :returns: The captured pane text, or ``None`` when no live pane exists.
    """
    info = read_tmux_info(bridge_dir)
    if info is None:
        return None
    socket_path, tmux_target = info["socket_path"], info["tmux_target"]
    if not _session_alive(socket_path, tmux_target):
        return None
    return _capture_pane(socket_path, tmux_target)


def send_cursor_pane_keys(bridge_dir: Path, *keys: str) -> None:
    """
    Send one or more keys to the Cursor pane (tmux ``send-keys``).

    Used by the approval mirror to answer cursor-agent's native prompt from a
    web verdict, e.g. ``"y"`` to approve or ``"Escape"`` to reject. Each key is
    a tmux key name/argument (not bracketed-paste data), so multi-byte keys like
    ``"Escape"`` are interpreted, not typed literally.

    :param bridge_dir: The cursor-native bridge dir holding ``tmux.json``.
    :param keys: tmux key arguments, e.g. ``"y"`` or ``"Escape"``.
    :raises RuntimeError: If the tmux target is not advertised or the
        ``send-keys`` invocation fails.
    """
    info = read_tmux_info(bridge_dir)
    if info is None:
        raise RuntimeError("cursor-native tmux target not advertised")
    _run_tmux(info["socket_path"], "send-keys", "-t", info["tmux_target"], *keys)


def _submit_needle(content: str) -> str:
    """A stable single-line substring used to confirm the paste rendered in the pane."""
    for line in content.splitlines():
        stripped = line.strip()
        if len(stripped) >= 4:
            return stripped[:24]
    stripped = content.strip()
    return stripped[:24] if len(stripped) >= 4 else ""


def _settle_pane(socket_path: str, tmux_target: str, *, timeout_s: float) -> None:
    """Best-effort wait until the Cursor input box is ready to receive a paste.

    Accepts the first-run "Trust this workspace" modal (sends ``a`` at most once)
    so the input box can mount, then waits for an idle/running input marker. Falls
    through after the timeout (mid-turn steering has no idle placeholder) rather
    than raising.
    """
    deadline = time.monotonic() + timeout_s
    trust_accepted = False
    while time.monotonic() < deadline:
        pane = _capture_pane(socket_path, tmux_target)
        if any(marker in pane for marker in _IDLE_MARKERS):
            return
        # One-shot, only when no input marker is up (so a later transcript that
        # merely echoes the phrase can't spray repeated keystrokes into the TUI).
        if not trust_accepted and _TRUST_MARKER in pane:
            trust_accepted = True
            with contextlib.suppress(RuntimeError):
                _run_tmux(socket_path, "send-keys", "-t", tmux_target, "a")
        time.sleep(_POLL_INTERVAL_S)


def _clear_composer(socket_path: str, tmux_target: str) -> None:
    """Empty the cursor-agent composer of any leftover draft before a paste.

    cursor-agent restores the interrupted prompt back into the composer when a
    turn is cancelled (Stop button -> :func:`inject_interrupt`), and its input
    widget ignores the readline ``C-a``/``C-k``/``C-u`` keys we'd otherwise use
    to clear a line — only ``Backspace`` deletes. So jump to the end (``End``)
    and flood ``Backspace`` in ``send-keys -N`` bursts until the pane stops
    changing (the draft is gone) or a generous round cap is hit. A burst against
    an already-empty composer is a harmless no-op (unlike ``C-c``, which would
    arm cursor-agent's exit), so this is safe to run before every injection.
    """
    _run_tmux(socket_path, "send-keys", "-t", tmux_target, "End")
    previous = _capture_pane(socket_path, tmux_target)
    for _ in range(_COMPOSER_CLEAR_MAX_ROUNDS):
        _run_tmux(
            socket_path,
            "send-keys",
            "-t",
            tmux_target,
            "-N",
            str(_COMPOSER_CLEAR_CHUNK),
            "BSpace",
        )
        current = _capture_pane(socket_path, tmux_target)
        # Once a burst no longer changes the pane, the composer is empty —
        # further Backspaces are no-ops, so stop.
        if current == previous:
            return
        previous = current


def inject_user_message(
    bridge_dir: Path,
    *,
    content: str,
    timeout_s: float = _TMUX_READY_TIMEOUT_S,
) -> None:
    """Deliver a web-UI user message into the Cursor TUI via a tmux bracketed paste.

    Clears any leftover draft, pastes *content* (multi-line safe via
    ``load-buffer``/``paste-buffer -p`` so interior newlines stay data, not
    submits), settles, then submits with Enter.

    :param bridge_dir: The cursor-native bridge dir holding ``tmux.json``.
    :param content: User text (non-empty).
    :param timeout_s: Per-readiness-gate timeout.
    :raises RuntimeError: If the tmux target is never advertised or a tmux
        command fails.
    """
    if not content:
        raise RuntimeError("cursor-native injection requires non-empty content")
    info = _wait_for_tmux_info(bridge_dir, timeout_s=timeout_s)
    socket_path = info["socket_path"]
    tmux_target = info["tmux_target"]
    # Fast-fail if the TUI already exited: otherwise _settle_pane polls a dead
    # pane for the full timeout and the web message is silently lost. A clear
    # error lets run_turn surface ExecutorError so the UI can say "restart".
    if not _session_alive(socket_path, tmux_target):
        raise RuntimeError(
            "cursor terminal is no longer running (the TUI exited); restart the session"
        )
    _settle_pane(socket_path, tmux_target, timeout_s=timeout_s)
    # Clear any leftover draft (e.g. the prompt cursor-agent restores into the
    # composer after a cancelled turn) so it can't prepend the new message.
    _clear_composer(socket_path, tmux_target)
    with tempfile.NamedTemporaryFile(
        dir=bridge_dir, prefix="paste_", suffix=".bin", delete=False
    ) as paste_file:
        # Trailing newline absorbs any trailing backslash so it can't escape Enter.
        paste_file.write(_paste_payload_bytes(content + "\n"))
        paste_path = paste_file.name
    try:
        _run_tmux(socket_path, "load-buffer", "-b", _PASTE_BUFFER, paste_path)
        _run_tmux(
            socket_path,
            "paste-buffer",
            "-p",  # bracketed-paste markers — the TUI keeps newlines as data
            "-d",  # drop the buffer after pasting
            "-b",
            _PASTE_BUFFER,
            "-t",
            tmux_target,
        )
    finally:
        with contextlib.suppress(OSError):
            os.unlink(paste_path)
    # Wait until the paste is visibly committed to the input box before Enter.
    # Submitting mid-paste folds the Enter in as a newline (the cursor TUI
    # coalesces rapid stdin bursts), leaving the message unsent. Poll for the
    # text, then submit; fall through to a blind submit if no needle is usable.
    needle = _submit_needle(content)
    if needle:
        deadline = time.monotonic() + _PASTE_COMMIT_TIMEOUT_S
        while time.monotonic() < deadline:
            if needle in _capture_pane(socket_path, tmux_target):
                break
            time.sleep(_POLL_INTERVAL_S)
    time.sleep(_PASTE_SETTLE_S)
    _run_tmux(socket_path, "send-keys", "-t", tmux_target, "Enter")


def inject_model_command(
    bridge_dir: Path,
    *,
    model: str,
    timeout_s: float = _TMUX_READY_TIMEOUT_S,
) -> None:
    """Switch the live Cursor model by driving the TUI ``/model`` picker.

    cursor-agent's ``--model`` flag is baked in at spawn, so a web-UI / REPL
    model switch on a *running* pane can't be applied by re-reading the
    persisted ``model_override`` — it has to be typed into the TUI. Typing
    ``/model <id>`` opens cursor-agent's model picker filtered to *model* and
    Enter selects the (now top) match; verified live that an exact model id
    selects exactly that model (e.g. ``gpt-5.2`` → "GPT-5.2 Medium"). This is
    the cursor analog of claude-native's ``inject_slash_command('/model …')``.

    :param bridge_dir: The cursor-native bridge dir holding ``tmux.json``.
    :param model: cursor-agent model id, e.g. ``"gpt-5.2"`` (the same ids
        ``cursor-agent --list-models`` reports).
    :param timeout_s: Per-readiness-gate timeout.
    :raises RuntimeError: If the tmux target is never advertised, the TUI has
        exited, a tmux command fails, or the picker reports no match for *model*
        (an unavailable/typo'd id) — in which case the picker is dismissed and
        the model is left unchanged rather than mis-selected.
    """
    model = model.strip()
    if not model:
        raise RuntimeError("cursor-native model switch requires a non-empty model id")
    info = _wait_for_tmux_info(bridge_dir, timeout_s=timeout_s)
    socket_path = info["socket_path"]
    tmux_target = info["tmux_target"]
    if not _session_alive(socket_path, tmux_target):
        raise RuntimeError(
            "cursor terminal is no longer running (the TUI exited); restart the session"
        )
    _settle_pane(socket_path, tmux_target, timeout_s=timeout_s)
    # Clear any leftover draft so the slash command isn't appended to it.
    # cursor-agent's composer ignores the readline C-a/C-k keys, so this floods
    # Backspace (see _clear_composer); a bare "/model <id>" is what opens the
    # picker, whereas "<draft>/model <id>" would not.
    _clear_composer(socket_path, tmux_target)
    # ``-l`` sends the command as literal characters so ``/`` opens the slash
    # menu and the id filters the picker rather than being parsed as key names.
    _run_tmux(socket_path, "send-keys", "-t", tmux_target, "-l", f"/model {model}")
    # Gate on the picker's *filter result*, not the echoed command: the composer
    # line itself contains ``model``, so a naive ``model in pane`` check passes
    # instantly off the echo and never confirms a match landed. Poll for cursor's
    # "Models matching" header (≥1 match) or "No matches", then settle so the
    # highlight stabilizes before Enter. The composer debounces input (~1.5s), so
    # both the filter and the highlight need time to resolve.
    deadline = time.monotonic() + _PASTE_COMMIT_TIMEOUT_S
    while time.monotonic() < deadline:
        pane = _capture_pane(socket_path, tmux_target)
        if _PICKER_NO_MATCH_MARKER in pane or _PICKER_MATCH_MARKER in pane:
            break
        time.sleep(_POLL_INTERVAL_S)
    time.sleep(_MODEL_PICKER_SETTLE_S)
    # Re-read after the settle: a transient "No matches" can flash mid-filter,
    # and a real match may only resolve once the debounce fires.
    if _PICKER_NO_MATCH_MARKER in _capture_pane(socket_path, tmux_target):
        # Dismiss the picker and clear the composer so the literal "/model <id>"
        # can't be submitted as a chat message, then fail loudly so the web
        # surfaces an honest error instead of silently selecting nothing.
        _run_tmux(socket_path, "send-keys", "-t", tmux_target, "Escape")
        _clear_composer(socket_path, tmux_target)
        raise RuntimeError(
            f"cursor model {model!r} is not available in the picker (no match); "
            "the model was not switched"
        )
    _run_tmux(socket_path, "send-keys", "-t", tmux_target, "Enter")


def _wait_for_pane_settle(socket_path: str, tmux_target: str, *, timeout_s: float) -> None:
    """Best-effort wait until the pane stops changing across two captures.

    Used after a cancel so the restored draft (and any final generation output)
    has landed before we clear the composer. Falls through after *timeout_s*
    rather than raising — the clear that follows is a no-op on an empty composer.
    """
    deadline = time.monotonic() + timeout_s
    previous = _capture_pane(socket_path, tmux_target)
    while time.monotonic() < deadline:
        time.sleep(_POLL_INTERVAL_S)
        current = _capture_pane(socket_path, tmux_target)
        if current and current == previous:
            return
        previous = current


def inject_interrupt(bridge_dir: Path, *, timeout_s: float = _TMUX_READY_TIMEOUT_S) -> None:
    """Cancel the in-flight Cursor turn and clear the composer.

    Sends ``Escape`` to stop the running turn, then clears the input box:
    cursor-agent restores the interrupted prompt into the composer on cancel, so
    without this the leftover prompt sits in the box and prepends the next
    message (the web UI's Stop button would otherwise leave a half-sent draft).
    The harness ``run_turn`` returns right after the paste, so the runner's
    in-process cancel floor can't reach the turn — this is the analog of
    :func:`inject_user_message` for the web UI's Stop button.

    :raises RuntimeError: If the tmux target is not advertised or send-keys fails.
    """
    info = _wait_for_tmux_info(bridge_dir, timeout_s=timeout_s)
    socket_path = info["socket_path"]
    tmux_target = info["tmux_target"]
    # No ``-l``: tmux must interpret ``Escape`` as a key name.
    _run_tmux(socket_path, "send-keys", "-t", tmux_target, "Escape")
    # Let the cancel land and the restored draft settle, then clear it. The
    # next injection also clears (defense in depth), but clearing here means the
    # composer is empty the moment the user looks at the TUI after pressing Stop.
    _wait_for_pane_settle(socket_path, tmux_target, timeout_s=_INTERRUPT_SETTLE_TIMEOUT_S)
    _clear_composer(socket_path, tmux_target)


def kill_session(bridge_dir: Path, *, timeout_s: float = _TMUX_READY_TIMEOUT_S) -> None:
    """Hard-stop the Cursor session by killing its tmux session.

    Terminates ``cursor-agent`` and the pane outright — the analog of the
    user manually exiting the attached TUI, for the web UI's "Stop session"
    affordance. Mirrors :func:`omnigent.claude_native_bridge.kill_session`.

    :raises RuntimeError: If the tmux target is not advertised or kill-session fails.
    """
    info = _wait_for_tmux_info(bridge_dir, timeout_s=timeout_s)
    _run_tmux(info["socket_path"], "kill-session", "-t", info["tmux_target"])