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tekton/addons/godot_ai/debugger/mcp_debugger_plugin.gd
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GDScript

@tool
class_name McpDebuggerPlugin
extends EditorDebuggerPlugin
const ErrorCodes := preload("res://addons/godot_ai/utils/error_codes.gd")
## Editor-side half of the game-process capture bridge.
##
## The game-side counterpart (`plugin/addons/godot_ai/runtime/game_helper.gd`,
## registered as autoload `_mcp_game_helper`) listens on EngineDebugger's
## message channel. This plugin sends "mcp:take_screenshot" requests and
## routes the replies back through the WebSocket McpConnection using the
## request_id the MCP dispatcher threaded through params.
##
## Why this exists: the game always runs as a separate OS process. Even
## "Embed Game Mode" on Windows/Linux (and macOS 4.5+) just reparents the
## game's window into the editor — the game's framebuffer is never reachable
## from the editor's Viewport. The debugger channel is the engine's own
## supported IPC and works identically regardless of embed mode.
const CAPTURE_PREFIX := "mcp"
## CI runners under xvfb can be slow to spin up the game subprocess and
## register the autoload's capture. 8s keeps the message responsive for
## interactive users while still covering slow-CI startup.
const DEFAULT_TIMEOUT_SEC := 8.0
## How long to wait for the game-side autoload to beacon mcp:hello
## before sending the screenshot request. Godot's debugger drops
## messages whose prefix has no registered capture, so sending
## take_screenshot before the game registers its "mcp" capture is a
## silent black hole. On CI the game subprocess has been observed
## taking ~15s to boot + register.
const GAME_READY_WAIT_SEC := 20.0
## #500: how long to wait for the game-side autoload to beacon mcp:hello before
## issuing a game_eval. This is deliberately MUCH shorter than the 20s
## screenshot wait above: the eval path's total editor-side budget is this wait
## plus the 10s eval backstop (request_game_eval's timeout_sec), and that total
## MUST stay below the 15s game_eval timeout enforced at two layers: the Python
## server's send_command budget (src/godot_ai/handlers/editor.py::game_eval) and
## this plugin's own deferred budget (dispatcher.gd's 15000ms game_eval entry,
## editor/plugin-side — not server-side). Either firing produces the opaque tail.
## With the 20s screenshot wait, a not-yet-ready game made the editor poll past
## the 15s deadline, so the server gave up first with an opaque
## ~15s TimeoutError instead of the actionable "Is the game actually running?"
## error below ever reaching the client (#500's residual TimeoutError bucket).
## 3s wait + 10s backstop = 13s, comfortably under the 15s server timeout, so
## the actionable error always wins. A game launched moments before the eval
## still has the 3s grace to register; if it needs longer, the user gets a fast,
## clear "is it running?" rather than a 15s hang.
const EVAL_READY_WAIT_SEC := 3.0
## #490: how long to wait for the game's mcp:eval_compiled beacon before
## concluding the eval source failed to compile. A parse error aborts the
## game-side handler before it can reply, so without this we'd wait the
## full eval timeout for a syntax mistake. reload() of valid source is
## sub-millisecond, so 3s is comfortably clear of false positives.
const EVAL_COMPILE_GRACE_SEC := 3.0
## #490: once an eval compiles, the editor polls the game every this many
## seconds with mcp:eval_check. A backgrounded play-in-editor game has a
## frozen idle loop (no _process / SceneTreeTimer ticks) so it can't
## self-report a runtime error that aborted the eval — but its debugger
## capture callback still answers a probe. The editor's own loop keeps
## ticking, so it drives the poll. 0.35s keeps detection well under a second
## without flooding the channel; most evals reply before the first probe.
const EVAL_PROBE_INTERVAL_SEC := 0.35
var _log_buffer: McpLogBuffer
var _game_log_buffer: McpGameLogBuffer
var _editor_log_buffer: McpEditorLogBuffer
## Pending request_id -> {connection, timer, timeout_callable}.
## We retain the bound timeout lambda so `_clear_pending` can disconnect
## it on success/error; otherwise the SceneTreeTimer pins the captured
## request_id until `timeout_sec` elapses (8s default).
var _pending: Dictionary = {}
## Flipped true when the game-side autoload sends its "mcp:hello" boot
## beacon for the current project_run. Reset as soon as a new run is
## requested, before Godot has attached the fresh debugger session, so
## editor_state cannot leak readiness from the previous game process.
var _game_ready := false
var _game_run_token := 0
var _ready_run_token := -1
var _game_session_id := -1
var _game_run_active := false
var _game_run_started_msec := 0
var _game_run_started_editor_cursor := 0
var _game_helper_expected := true
signal game_ready
func _init(log_buffer: McpLogBuffer = null, game_log_buffer: McpGameLogBuffer = null, editor_log_buffer: McpEditorLogBuffer = null) -> void:
_log_buffer = log_buffer
_game_log_buffer = game_log_buffer
_editor_log_buffer = editor_log_buffer
func _has_capture(prefix: String) -> bool:
return prefix == CAPTURE_PREFIX
## Fires when a debugger session attaches — once for the editor's own
## self-session at startup, and again each time the user hits Play and a
## new game subprocess connects. Reset _game_ready so the next capture
## request waits for the (new) game's mcp:hello beacon before sending,
## avoiding stale-flag timeouts across Play→Stop→Play cycles.
##
## Do NOT log here: add_debugger_plugin() triggers this virtual before
## plugin.gd's _enter_tree logs "plugin loaded", and ci-reload-test
## asserts "plugin loaded" is the first line after a plugin reload.
func _setup_session(session_id: int) -> void:
_game_ready = false
_ready_run_token = -1
_game_session_id = session_id
func begin_game_run(editor_log_cursor: int = 0, helper_expected: bool = true) -> void:
_game_run_token += 1
_game_run_active = true
_game_ready = false
_ready_run_token = -1
_game_session_id = -1
_game_run_started_msec = Time.get_ticks_msec()
_game_run_started_editor_cursor = maxi(0, editor_log_cursor)
_game_helper_expected = helper_expected
var run_id := ""
if _game_log_buffer:
run_id = _game_log_buffer.clear_for_new_run()
if _log_buffer:
var log_text := "[debug] game capture pending run token %d" % _game_run_token
if not run_id.is_empty():
log_text += " (run %s)" % run_id
_log_buffer.log(log_text)
func end_game_run() -> void:
_game_run_active = false
_game_ready = false
_ready_run_token = -1
_game_session_id = -1
func is_game_capture_ready() -> bool:
return _game_run_active and _game_ready and _ready_run_token == _game_run_token
static func with_liveness_flags(status: Dictionary) -> Dictionary:
var enriched := status.duplicate(true)
var state := str(enriched.get("status", "stopped"))
enriched["helper_live"] = state == "live"
enriched["session_active"] = not state in ["not_live", "stopped"]
return enriched
func get_game_status(now_msec: int = -1, ready_wait_sec: float = GAME_READY_WAIT_SEC) -> Dictionary:
var resolved_now := Time.get_ticks_msec() if now_msec < 0 else now_msec
var ready_wait_msec := maxi(0, int(ready_wait_sec * 1000.0))
var elapsed_msec := maxi(0, resolved_now - _game_run_started_msec) if _game_run_active else 0
## "stopped" also covers idle/never-ran; no game run is currently active.
var status := "stopped"
if _game_run_active:
if is_game_capture_ready():
status = "live"
elif not _game_helper_expected:
status = "no_helper"
elif elapsed_msec >= ready_wait_msec:
status = "not_live"
else:
status = "launching"
return with_liveness_flags({
"status": status,
"run_token": _game_run_token,
"active": _game_run_active,
"ready": is_game_capture_ready(),
"helper_expected": _game_helper_expected,
"run_started_msec": _game_run_started_msec,
"elapsed_msec": elapsed_msec,
"ready_wait_msec": ready_wait_msec,
"editor_log_cursor": _game_run_started_editor_cursor,
})
func _explain_not_live(status: Dictionary, code: String = ErrorCodes.INTERNAL_ERROR) -> Dictionary:
var state := str(status.get("status", "stopped"))
var errors_info := recent_editor_errors_since(int(status.get("editor_log_cursor", 0)))
var recent_errors: Array = errors_info.get("errors", [])
var recent_errors_scope := str(errors_info.get("scope", "none"))
var truncated := bool(errors_info.get("truncated", false))
var data := {
"game_status": status.duplicate(true),
"recent_errors": recent_errors,
"recent_errors_scope": recent_errors_scope,
"recent_errors_may_predate_run": recent_errors_scope == "retained_recent",
"recent_errors_truncated": truncated,
}
var message := ""
match state:
"not_live":
if not recent_errors.is_empty() and recent_errors_scope == "run":
message = "The game failed to load or crashed before the Godot AI game helper registered: %s. Check logs_read(source='editor', include_details=true)." % _format_editor_error_summary(recent_errors[0])
if truncated:
message += " Editor logs since this run may be truncated; showing retained errors."
elif not recent_errors.is_empty():
message = "The game is not responding and reported no load errors during this run. A recent editor error may be related, but may predate this run: %s. Check logs_read(source='editor', include_details=true)." % _format_editor_error_summary(recent_errors[0])
else:
message = "The game is not responding and reported no load errors before the helper-ready window elapsed. It may still be booting or may have failed silently; check logs_read(source='editor', include_details=true) and retry."
"no_helper":
message = "The running game has no _mcp_game_helper autoload, so game-side tools cannot connect. If this is a headless or custom-main-loop project, use editor_screenshot(source='viewport') where applicable. Otherwise, re-enable the plugin and relaunch the game."
"launching":
message = "The game is still starting (%.1fs elapsed); the Godot AI game helper has not registered yet. Retry shortly." % (float(status.get("elapsed_msec", 0)) / 1000.0)
"stopped":
message = "The game is not running. Start the project and retry the game-side tool."
_:
message = "The game-side tool could not confirm the game is live (status=%s). Check logs_read(source='editor', include_details=true) and retry." % state
var err := ErrorCodes.make(code, message)
var inner: Dictionary = err.get("error", {})
inner["data"] = data
err["error"] = inner
return err
func recent_editor_errors_since(cursor: int) -> Dictionary:
return _recent_editor_errors_since(cursor)
func _recent_editor_errors_since(cursor: int) -> Dictionary:
var out: Array[Dictionary] = []
var truncated := false
if _editor_log_buffer == null:
return {"errors": out, "truncated": false, "scope": "none"}
var captured: Dictionary = _editor_log_buffer.get_since(maxi(0, cursor), -1)
truncated = bool(captured.get("truncated", false))
for raw_entry in captured.get("entries", []):
var compact := _compact_editor_error(raw_entry)
if compact.is_empty():
continue
out.append(compact)
if out.size() >= 5:
break
if not out.is_empty():
return {"errors": out, "truncated": truncated, "scope": "run"}
for raw_entry in _reversed_entries(_editor_log_buffer.get_recent(McpEditorLogBuffer.MAX_LINES)):
var compact := _compact_editor_error(raw_entry, true)
if compact.is_empty():
continue
out.append(compact)
if out.size() >= 5:
break
if not out.is_empty():
return {"errors": out, "truncated": false, "scope": "retained_recent"}
return {"errors": out, "truncated": false, "scope": "none"}
func _compact_editor_error(raw_entry: Variant, fallback_recent: bool = false) -> Dictionary:
if not raw_entry is Dictionary:
return {}
var entry := raw_entry as Dictionary
if str(entry.get("level", "info")) != "error":
return {}
var path := str(entry.get("path", ""))
if fallback_recent and _is_diagnostic_noise_path(path):
return {}
var compact := {
"source": "editor",
"level": "error",
"text": str(entry.get("text", "")),
"path": path,
"line": int(entry.get("line", 0)),
"function": str(entry.get("function", "")),
}
if entry.has("details"):
compact["details"] = entry["details"].duplicate(true)
return compact
func _is_diagnostic_noise_path(path: String) -> bool:
return path.begins_with("res://addons/godot_ai/") or path.begins_with("res://tests/")
func _reversed_entries(entries: Array[Dictionary]) -> Array[Dictionary]:
var out: Array[Dictionary] = []
for i in range(entries.size() - 1, -1, -1):
out.append(entries[i])
return out
func _format_editor_error_summary(entry: Dictionary) -> String:
var text := str(entry.get("text", "editor error"))
var path := str(entry.get("path", ""))
var line := int(entry.get("line", 0))
if not path.is_empty() and line > 0:
return "%s (%s:%d)" % [text, path, line]
if not path.is_empty():
return "%s (%s)" % [text, path]
return text
func _capture(message: String, data: Array, session_id: int) -> bool:
## Godot passes the full "prefix:tail" string as `message`.
match message:
"mcp:screenshot_response":
_on_screenshot_response(data)
return true
"mcp:screenshot_error":
_on_screenshot_error(data)
return true
"mcp:log_batch":
_on_log_batch(data)
return true
"mcp:hello":
if not _game_run_active:
if _log_buffer:
_log_buffer.log("[debug] ignored mcp:hello with no active game run")
return true
if _game_session_id != -1 and session_id != _game_session_id:
if _log_buffer:
_log_buffer.log("[debug] ignored stale mcp:hello from debugger session %d (current %d)" % [session_id, _game_session_id])
return true
## Boot beacon from the game-side autoload. Tells us the
## game has registered its "mcp" capture and is safe to send
## take_screenshot to — before this, Godot's debugger would
## drop our message silently.
_game_ready = true
_ready_run_token = _game_run_token
game_ready.emit()
if _log_buffer:
if _game_log_buffer:
_log_buffer.log("[debug] <- mcp:hello from game_helper (run %s)" % _game_log_buffer.run_id())
else:
_log_buffer.log("[debug] <- mcp:hello from game_helper")
return true
"mcp:eval_response":
_on_eval_response(data)
return true
"mcp:eval_error":
_on_eval_error(data)
return true
"mcp:eval_ack":
_on_eval_ack(data)
return true
"mcp:eval_compiled":
_on_eval_compiled(data)
return true
"mcp:eval_runtime_error":
_on_eval_runtime_error(data)
return true
"mcp:game_command_response":
_on_game_command_response(data)
return true
"mcp:game_command_error":
_on_game_command_error(data)
return true
return false
func _on_log_batch(data: Array) -> void:
if _game_log_buffer == null:
return
## data layout: [[[level, text, details?], ...]]
if data.is_empty() or not (data[0] is Array):
return
var entries: Array = data[0]
for entry in entries:
if entry is Dictionary:
var dict_details: Dictionary = {}
var raw_dict_details = entry.get("details", {})
if raw_dict_details is Dictionary:
dict_details = raw_dict_details
_game_log_buffer.append(str(entry.get("level", "info")), str(entry.get("text", "")), dict_details)
continue
if not (entry is Array) or entry.size() < 2:
continue
var details: Dictionary = {}
if entry.size() > 2 and entry[2] is Dictionary:
details = entry[2]
_game_log_buffer.append(str(entry[0]), str(entry[1]), details)
## Request a game-process framebuffer capture over the debugger channel.
## Reply is pushed back through `connection` out-of-band because the MCP
## dispatcher has already returned a deferred-response marker for this
## request_id. Synchronous from the caller's perspective — if the
## game-side autoload hasn't beaconed yet, the wait + send run as a
## fire-and-forget coroutine kicked off from here. Structured this way
## so the call site in EditorHandler stays a plain non-await invocation.
func request_game_screenshot(
request_id: String,
max_resolution: int,
connection: McpConnection,
timeout_sec: float = DEFAULT_TIMEOUT_SEC,
) -> void:
if request_id.is_empty():
push_warning("MCP debugger: screenshot request missing request_id")
return
var tree := Engine.get_main_loop() as SceneTree
if tree == null:
_send_error(connection, request_id, ErrorCodes.INTERNAL_ERROR,
"Editor main loop is not a SceneTree — cannot schedule capture")
return
if is_game_capture_ready():
_send_take_screenshot(tree, request_id, max_resolution, connection, timeout_sec)
return
## Not ready yet — run the wait-then-send flow as a detached
## coroutine. It keeps itself alive via the signal subscription on
## tree.process_frame; the caller doesn't need to (and shouldn't)
## await this entrypoint.
if _log_buffer:
_log_buffer.log("[debug] waiting for game_helper hello (%s)" % request_id)
_wait_then_send(tree, request_id, max_resolution, connection, timeout_sec)
## Coroutine: poll each editor frame until the mcp:hello beacon arrives
## (flipping _game_ready true) or the deadline elapses. Once resolved,
## either dispatch the capture or return an actionable timeout error.
func _wait_then_send(
tree: SceneTree,
request_id: String,
max_resolution: int,
connection: McpConnection,
timeout_sec: float,
) -> void:
var deadline := Time.get_ticks_msec() + int(GAME_READY_WAIT_SEC * 1000.0)
while not is_game_capture_ready() and Time.get_ticks_msec() < deadline:
await tree.process_frame
if not is_game_capture_ready():
_send_error_response(connection, request_id,
_explain_not_live(get_game_status(-1, GAME_READY_WAIT_SEC), ErrorCodes.INTERNAL_ERROR))
return
_send_take_screenshot(tree, request_id, max_resolution, connection, timeout_sec)
## Send the mcp:take_screenshot message and arm the reply timeout.
## Assumes _game_ready is true.
func _send_take_screenshot(
tree: SceneTree,
request_id: String,
max_resolution: int,
connection: McpConnection,
timeout_sec: float,
) -> void:
var session: EditorDebuggerSession = _first_active_session()
if session == null:
_send_error(connection, request_id, ErrorCodes.INTERNAL_ERROR,
"No active debugger session — is the game actually running and started from this editor?")
return
var timer: SceneTreeTimer = tree.create_timer(timeout_sec)
var timeout_callable := func() -> void: _on_timeout(request_id)
timer.timeout.connect(timeout_callable)
_pending[request_id] = {
"connection": connection,
"timer": timer,
"timeout_callable": timeout_callable,
}
session.send_message("mcp:take_screenshot", [request_id, max_resolution])
if _log_buffer:
_log_buffer.log("[debug] -> mcp:take_screenshot (%s)" % request_id)
func _first_active_session() -> EditorDebuggerSession:
for s in get_sessions():
if s is EditorDebuggerSession and s.is_active():
return s
return null
func _on_screenshot_response(data: Array) -> void:
if data.size() < 6:
push_warning("MCP debugger: malformed screenshot response (expected 6 fields, got %d)" % data.size())
return
var request_id: String = data[0]
var pending = _pending.get(request_id)
if pending == null:
## Timed out or unknown — silently drop.
return
_clear_pending(request_id)
var connection: McpConnection = pending.connection
if connection == null or not is_instance_valid(connection):
return
connection.send_deferred_response(request_id, {
"data": {
"source": "game",
"width": int(data[2]),
"height": int(data[3]),
"original_width": int(data[4]),
"original_height": int(data[5]),
"format": "png",
"image_base64": data[1],
}
})
if _log_buffer:
_log_buffer.log("[debug] <- mcp:screenshot_response (%s)" % request_id)
func _on_screenshot_error(data: Array) -> void:
if data.size() < 2:
return
var request_id: String = data[0]
var message: String = data[1]
var pending = _pending.get(request_id)
if pending == null:
return
_clear_pending(request_id)
var connection: McpConnection = pending.connection
if connection == null or not is_instance_valid(connection):
return
_send_error(connection, request_id, ErrorCodes.INTERNAL_ERROR, message)
func _on_timeout(request_id: String) -> void:
var pending = _pending.get(request_id)
if pending == null:
return
_pending.erase(request_id)
var connection: McpConnection = pending.connection
if connection == null or not is_instance_valid(connection):
return
var status := get_game_status(-1, GAME_READY_WAIT_SEC)
var err := ErrorCodes.make(ErrorCodes.INTERNAL_ERROR,
"Game screenshot timed out after reaching the game helper. The game may be busy or unable to render a frame. Check logs_read(source='game') and retry.")
if status.get("status", "") != "live":
err = _explain_not_live(status, ErrorCodes.INTERNAL_ERROR)
_send_error_response(connection, request_id, err)
if _log_buffer:
_log_buffer.log("[debug] !! screenshot timeout (%s)" % request_id)
func _send_error(connection: McpConnection, request_id: String, code: String, message: String) -> void:
_send_error_response(connection, request_id, ErrorCodes.make(code, message))
func _send_error_response(connection: McpConnection, request_id: String, err: Dictionary) -> void:
if connection == null or not is_instance_valid(connection):
return
connection.send_deferred_response(request_id, err)
func _clear_pending(request_id: String) -> void:
var pending: Dictionary = _pending.get(request_id, {})
var timer: SceneTreeTimer = pending.get("timer")
var cb: Callable = pending.get("timeout_callable", Callable())
if timer != null and timer.timeout.is_connected(cb):
timer.timeout.disconnect(cb)
## #490: eval requests also carry a compile-grace timer and a runtime probe.
var grace: SceneTreeTimer = pending.get("grace_timer")
var gcb: Callable = pending.get("grace_callable", Callable())
if grace != null and grace.timeout.is_connected(gcb):
grace.timeout.disconnect(gcb)
var probe: SceneTreeTimer = pending.get("probe_timer")
var pcb: Callable = pending.get("probe_callable", Callable())
if probe != null and probe.timeout.is_connected(pcb):
probe.timeout.disconnect(pcb)
_pending.erase(request_id)
## --- game_eval: execute arbitrary GDScript in the running game ---
## Editor-side fallback timer for game_eval. MUST stay above the game-side
## EVAL_TIMEOUT_SEC (8.0) in runtime/game_helper.gd and below the dispatcher's
## game_eval budget (15000 ms) in dispatcher.gd — i.e. game 8s < editor 10s <
## dispatcher 15s. This timer only fires when the game never replies at all,
## and its message (the timeout_callable below) is intentionally generic. Drop
## timeout_sec at/below 8s and it pre-empts the game's actionable "Eval
## exceeded 8s" message — see the TIMEOUT ORDERING note on EVAL_TIMEOUT_SEC.
##
## #500: the *not-ready* path adds EVAL_READY_WAIT_SEC (3s) on top of this 10s
## backstop. That sum (13s) must also stay below the dispatcher/server 15s
## budget, or a not-yet-ready game makes the server time out opaquely before
## the editor's actionable error returns — which is exactly the residual ~15s
## TimeoutError bucket #500 tracked down. Keep EVAL_READY_WAIT_SEC + timeout_sec
## < 15s if you tune either.
func request_game_eval(
code: String,
request_id: String,
connection: McpConnection,
timeout_sec: float = 10.0,
) -> void:
if request_id.is_empty():
push_warning("MCP debugger: eval request missing request_id")
return
var tree := Engine.get_main_loop() as SceneTree
if tree == null:
_send_error(connection, request_id, ErrorCodes.INTERNAL_ERROR,
"Editor main loop is not a SceneTree — cannot schedule eval")
return
if is_game_capture_ready():
_send_eval(tree, code, request_id, connection, timeout_sec)
return
if _log_buffer:
_log_buffer.log("[debug] waiting for game_helper hello before eval (%s)" % request_id)
_wait_then_eval(tree, code, request_id, connection, timeout_sec)
func _wait_then_eval(
tree: SceneTree,
code: String,
request_id: String,
connection: McpConnection,
timeout_sec: float,
) -> void:
## #500: eval uses EVAL_READY_WAIT_SEC (not the 20s GAME_READY_WAIT_SEC) so
## the not-ready path returns its actionable error before the 15s server-side
## command timeout fires an opaque TimeoutError. See EVAL_READY_WAIT_SEC.
var deadline := Time.get_ticks_msec() + int(EVAL_READY_WAIT_SEC * 1000.0)
while not is_game_capture_ready() and Time.get_ticks_msec() < deadline:
await tree.process_frame
if not is_game_capture_ready():
## #518: EVAL_GAME_NOT_READY (not INTERNAL_ERROR) — the play session is up
## but the game-side capture didn't register within the short wait. Fast
## and caller-actionable; classifying it apart from the opaque 10s hang
## keeps the INTERNAL_ERROR telemetry bucket meaning "the eval truly hung".
_send_error_response(connection, request_id,
_explain_not_live(get_game_status(-1, EVAL_READY_WAIT_SEC), ErrorCodes.EVAL_GAME_NOT_READY))
return
_send_eval(tree, code, request_id, connection, timeout_sec)
func _send_eval(
tree: SceneTree,
code: String,
request_id: String,
connection: McpConnection,
timeout_sec: float,
) -> void:
var session: EditorDebuggerSession = _first_active_session()
if session == null:
## #518: capture reported ready but the debugger session is no longer live
## (the game just stopped / is restarting) — a not-ready race, so the same
## caller-actionable EVAL_GAME_NOT_READY rather than the opaque hang bucket.
_send_error(connection, request_id, ErrorCodes.EVAL_GAME_NOT_READY,
"Game-side capture registered but its debugger session is no longer active — the game likely just stopped or is restarting. Confirm it's running and retry.")
return
var timer: SceneTreeTimer = tree.create_timer(timeout_sec)
var timeout_callable := func() -> void:
var pending_entry = _pending.get(request_id)
if pending_entry == null:
return
_clear_pending(request_id)
var conn: McpConnection = pending_entry.connection
if conn == null or not is_instance_valid(conn):
return
_send_error(conn, request_id, ErrorCodes.INTERNAL_ERROR,
"Game eval compiled and started running but never returned within %.0fs — the code is likely stuck in an infinite loop or awaiting a signal/timer that never fires. Check logs_read(source='game')." % timeout_sec)
if _log_buffer:
_log_buffer.log("[debug] !! eval timeout (%s)" % request_id)
timer.timeout.connect(timeout_callable)
## #490: arm the compile-grace timer. _on_eval_grace concludes a parse error
## only when the game acked the eval (it received the message and started
## reload()) but never sent mcp:eval_compiled — see there for why a missing
## ack must NOT be read as a compile error.
var grace: SceneTreeTimer = tree.create_timer(EVAL_COMPILE_GRACE_SEC)
var grace_callable := func() -> void: _on_eval_grace(request_id)
grace.timeout.connect(grace_callable)
_pending[request_id] = {
"connection": connection,
"timer": timer,
"timeout_callable": timeout_callable,
"grace_timer": grace,
"grace_callable": grace_callable,
"acked": false,
"compiled": false,
}
session.send_message("mcp:eval", [request_id, code])
if _log_buffer:
_log_buffer.log("[debug] -> mcp:eval (%s)" % request_id)
func _on_eval_response(data: Array) -> void:
if data.size() < 2:
push_warning("MCP debugger: malformed eval response (expected 2 fields, got %d)" % data.size())
return
var request_id: String = data[0]
var pending_entry = _pending.get(request_id)
if pending_entry == null:
return
_clear_pending(request_id)
var connection: McpConnection = pending_entry.connection
if connection == null or not is_instance_valid(connection):
return
var result_json: String = data[1] if data.size() > 1 else "null"
var json := JSON.new()
var parse_err := json.parse(result_json)
connection.send_deferred_response(request_id, {
"data": {
"result": json.data if parse_err == OK else result_json,
"source": "game",
}
})
if _log_buffer:
_log_buffer.log("[debug] <- mcp:eval_response (%s)" % request_id)
func _on_eval_error(data: Array) -> void:
if data.size() < 2:
return
var request_id: String = data[0]
var message: String = data[1]
var pending_entry = _pending.get(request_id)
if pending_entry == null:
return
_clear_pending(request_id)
var connection: McpConnection = pending_entry.connection
if connection == null or not is_instance_valid(connection):
return
_send_error(connection, request_id, ErrorCodes.INTERNAL_ERROR, message)
if _log_buffer:
_log_buffer.log("[debug] <- mcp:eval_error (%s): %s" % [request_id, message])
## #490: the game sends this at the top of _handle_eval, BEFORE reload() (so it
## survives a parse-error abort). It positively signals "the game received this
## eval and started compiling it" — letting _on_eval_grace tell a real parse
## error (acked, never compiled) apart from a message the game hasn't serviced
## yet (never acked — main thread blocked by a long frame/load or a CPU-bound
## prior eval).
func _on_eval_ack(data: Array) -> void:
if data.is_empty():
return
var request_id: String = data[0]
var pending_entry = _pending.get(request_id)
if pending_entry == null:
return
pending_entry["acked"] = true
if _log_buffer:
_log_buffer.log("[debug] <- mcp:eval_ack (%s)" % request_id)
## #490: compile-grace timer fired. Conclude a parse error ONLY when the game
## acked the eval (started reload()) but never sent mcp:eval_compiled. If it
## never acked, the game simply hasn't serviced the message yet — NOT a parse
## error — so leave _pending intact and let the normal eval timeout handle it
## rather than false-failing a valid eval and dropping its eventual real reply.
func _on_eval_grace(request_id: String) -> void:
var pending_entry = _pending.get(request_id)
if pending_entry == null or pending_entry.get("compiled", false):
return
if not pending_entry.get("acked", false):
if _log_buffer:
_log_buffer.log("[debug] eval grace: no ack yet, deferring to timeout (%s)" % request_id)
return
_clear_pending(request_id)
var conn: McpConnection = pending_entry.connection
if conn == null or not is_instance_valid(conn):
return
_send_error(conn, request_id, ErrorCodes.EVAL_COMPILE_ERROR,
"Game eval failed to compile — likely a GDScript syntax/parse error. The parse error text is in the editor's Output/Debugger panel; it is not capturable from the running game. Check your eval code's syntax.")
if _log_buffer:
_log_buffer.log("[debug] !! eval compile error (%s)" % request_id)
## #490: the game sends this the instant reload() of the eval source
## succeeds. Flips the pending entry's `compiled` flag so the compile-grace
## timer won't fire a false EVAL_COMPILE_ERROR.
func _on_eval_compiled(data: Array) -> void:
if data.is_empty():
return
var request_id: String = data[0]
var pending_entry = _pending.get(request_id)
if pending_entry == null:
return
pending_entry["compiled"] = true
if _log_buffer:
_log_buffer.log("[debug] <- mcp:eval_compiled (%s)" % request_id)
## #490: compiled OK — start polling for a runtime error that may have
## aborted execute(). A backgrounded game can't self-report it, so the
## editor probes via mcp:eval_check until the eval resolves.
_arm_eval_probe(request_id)
## #490: the game reported a runtime error that aborted the eval — either
## from its _process fast path (focused game) or in answer to an editor
## eval_check probe (backgrounded game). Reply fast with the real error text
## instead of waiting for the hang timeout.
func _on_eval_runtime_error(data: Array) -> void:
if data.size() < 2:
return
var request_id: String = data[0]
var message: String = data[1]
var pending_entry = _pending.get(request_id)
if pending_entry == null:
return
_clear_pending(request_id)
var connection: McpConnection = pending_entry.connection
if connection == null or not is_instance_valid(connection):
return
var msg := "Game eval raised a runtime error: %s" % message if not message.is_empty() else "Game eval raised a runtime error (no message captured). Check logs_read(source='game')."
_send_error(connection, request_id, ErrorCodes.EVAL_RUNTIME_ERROR, msg)
if _log_buffer:
_log_buffer.log("[debug] <- mcp:eval_runtime_error (%s): %s" % [request_id, message])
## #490: arm one probe tick for an in-flight eval. Re-arms itself each tick
## until the request resolves — eval_response / eval_runtime_error /
## eval_compile_error / hang-timeout all call _clear_pending, which erases the
## entry and stops the chain. Uses the editor's own SceneTreeTimer because the
## editor loop keeps ticking even while a backgrounded game's loop is frozen.
func _arm_eval_probe(request_id: String) -> void:
var pending_entry = _pending.get(request_id)
if pending_entry == null:
return
var tree := Engine.get_main_loop() as SceneTree
if tree == null:
return
var probe_timer: SceneTreeTimer = tree.create_timer(EVAL_PROBE_INTERVAL_SEC)
var probe_callable := func() -> void: _on_eval_probe_tick(request_id)
pending_entry["probe_timer"] = probe_timer
pending_entry["probe_callable"] = probe_callable
probe_timer.timeout.connect(probe_callable)
## #490: poke the game for a runtime-error verdict, then re-arm. The game's
## _handle_eval_check answers with mcp:eval_runtime_error if a script error
## aborted this eval, else stays silent and we poll again next interval.
func _on_eval_probe_tick(request_id: String) -> void:
if not _pending.has(request_id):
return ## resolved — stop probing
var session: EditorDebuggerSession = _first_active_session()
if session != null and session.is_active():
session.send_message("mcp:eval_check", [request_id])
_arm_eval_probe(request_id)
## --- game_command: curated runtime game operations ---
func request_game_command(
op: String,
params: Dictionary,
request_id: String,
connection: McpConnection,
timeout_sec: float = 10.0,
) -> void:
if request_id.is_empty():
push_warning("MCP debugger: game command request missing request_id")
return
var tree := Engine.get_main_loop() as SceneTree
if tree == null:
_send_error(connection, request_id, ErrorCodes.INTERNAL_ERROR,
"Editor main loop is not a SceneTree — cannot schedule game command")
return
if is_game_capture_ready():
_send_game_command(tree, op, params, request_id, connection, timeout_sec)
return
if _log_buffer:
_log_buffer.log("[debug] waiting for game_helper hello before game_command (%s)" % request_id)
_wait_then_game_command(tree, op, params, request_id, connection, timeout_sec)
func _wait_then_game_command(
tree: SceneTree,
op: String,
params: Dictionary,
request_id: String,
connection: McpConnection,
timeout_sec: float,
) -> void:
var deadline := Time.get_ticks_msec() + int(GAME_READY_WAIT_SEC * 1000.0)
while not is_game_capture_ready() and Time.get_ticks_msec() < deadline:
await tree.process_frame
if not is_game_capture_ready():
_send_error_response(connection, request_id,
_explain_not_live(get_game_status(-1, GAME_READY_WAIT_SEC), ErrorCodes.INTERNAL_ERROR))
return
_send_game_command(tree, op, params, request_id, connection, timeout_sec)
func _send_game_command(
tree: SceneTree,
op: String,
params: Dictionary,
request_id: String,
connection: McpConnection,
timeout_sec: float,
) -> void:
var session: EditorDebuggerSession = _first_active_session()
if session == null:
_send_error(connection, request_id, ErrorCodes.INTERNAL_ERROR,
"No active debugger session — is the game actually running?")
return
var timer: SceneTreeTimer = tree.create_timer(timeout_sec)
var timeout_callable := func() -> void:
var pending_entry = _pending.get(request_id)
if pending_entry == null:
return
_pending.erase(request_id)
var conn: McpConnection = pending_entry.connection
if conn == null or not is_instance_valid(conn):
return
_send_error(conn, request_id, ErrorCodes.INTERNAL_ERROR,
"Game command '%s' timed out after %.0fs" % [op, timeout_sec])
if _log_buffer:
_log_buffer.log("[debug] !! game_command timeout (%s)" % request_id)
timer.timeout.connect(timeout_callable)
_pending[request_id] = {
"connection": connection,
"timer": timer,
"timeout_callable": timeout_callable,
}
session.send_message("mcp:game_command", [request_id, op, JSON.stringify(params)])
if _log_buffer:
_log_buffer.log("[debug] -> mcp:game_command %s (%s)" % [op, request_id])
func _on_game_command_response(data: Array) -> void:
if data.size() < 2:
push_warning("MCP debugger: malformed game_command response (expected 2 fields, got %d)" % data.size())
return
var request_id: String = data[0]
var pending_entry = _pending.get(request_id)
if pending_entry == null:
return
_clear_pending(request_id)
var connection: McpConnection = pending_entry.connection
if connection == null or not is_instance_valid(connection):
return
var result_json: String = data[1] if data.size() > 1 else "{}"
var json := JSON.new()
var parse_err := json.parse(result_json)
connection.send_deferred_response(request_id, {
"data": json.data if parse_err == OK else {"source": "game", "result": result_json}
})
if _log_buffer:
_log_buffer.log("[debug] <- mcp:game_command_response (%s)" % request_id)
func _on_game_command_error(data: Array) -> void:
if data.size() < 2:
return
var request_id: String = data[0]
var message: String = data[1]
var pending_entry = _pending.get(request_id)
if pending_entry == null:
return
_clear_pending(request_id)
var connection: McpConnection = pending_entry.connection
if connection == null or not is_instance_valid(connection):
return
_send_error(connection, request_id, ErrorCodes.INTERNAL_ERROR, message)
if _log_buffer:
_log_buffer.log("[debug] <- mcp:game_command_error (%s): %s" % [request_id, message])