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fix(tracing): capture completed McpToolCall items as named tool calls #106

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fix(tracing): capture completed McpToolCall items as named tool calls #106

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52 changes: 52 additions & 0 deletions plugins/tracing/src/parse.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -76,6 +76,16 @@ export function parseArgs(raw: string): unknown {
}
}

function mcpToolCallError(result: unknown): string {
if (typeof result === "string" && result) return result;
if (result !== null && typeof result === "object") {
const r = result as Record<string, unknown>;
if (typeof r.Err === "string" && r.Err) return r.Err;
if (typeof r.error === "string" && r.error) return r.error;
}
return "MCP tool call failed";
}

function extractToolError(payload: EventMsgPayload): string | undefined {
const explicit = payload.error ?? payload.codex_error_info;
if (explicit != null) {
Expand Down Expand Up @@ -375,6 +385,48 @@ export function parseSession(lines: RolloutLine[]): {
} else if (et === "item_completed" && p.item?.type === "UserMessage") {
const text = extractMessageText(p.item.content);
if (text && !turn!.userInput) turn!.userInput = text;
} else if (et === "item_completed" && p.item?.type === "McpToolCall") {
// Why: Desktop code-mode surfaces nested MCP calls only as completed McpToolCall items -
// no mcp_tool_call_begin/end events and no model-visible call to enrich.
const item = p.item as {
id?: unknown;
server?: unknown;
tool?: unknown;
arguments?: unknown;
result?: unknown;
status?: unknown;
};
if (
typeof item.id === "string" &&
typeof item.server === "string" &&
typeof item.tool === "string"
) {
const failed = item.status === "failed";
const existing = toolCallsById.get(item.id);
if (existing) {
existing.mcp = existing.mcp ?? { server: item.server, tool: item.tool };
if (!failed && existing.output == null && item.result !== undefined) {
existing.output = item.result;
}
existing.endTime = Math.max(existing.endTime ?? ts, ts);
if (failed && !existing.error) existing.error = mcpToolCallError(item.result);
} else {
// startTime is the completion time: the item's duration has no documented
// serialized shape, so don't guess units from it.
const s = ensureStep(ts);
const tc: ToolCall = {
callId: item.id,
name: `${item.server}.${item.tool}`,
args: item.arguments,
startTime: ts,
endTime: ts,
...(failed ? { error: mcpToolCallError(item.result) } : { output: item.result }),
mcp: { server: item.server, tool: item.tool },
};
s.toolCalls.push(tc);
toolCallsById.set(tc.callId, tc);
}
}
} else if (et === "agent_message" && typeof p.message === "string") {
turn!.lastAgentMessage = p.message;
} else if (et === "token_count") {
Expand Down
87 changes: 87 additions & 0 deletions plugins/tracing/test/parse.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -536,6 +536,93 @@ describe("parseSession", () => {
expect(mcp?.mcp).toEqual({ server: "linear", tool: "create_issue" });
});

it("captures completed McpToolCall items from Desktop code-mode turns", () => {
const lines: RolloutLine[] = [
{ timestamp: "2026-06-03T12:00:00.000Z", type: "session_meta", payload: { id: "s" } },
{
timestamp: "2026-06-03T12:00:01.000Z",
type: "event_msg",
payload: { type: "task_started", turn_id: "t" },
},
{
timestamp: "2026-06-03T12:00:02.000Z",
type: "event_msg",
payload: {
type: "item_completed",
item: {
type: "McpToolCall",
id: "mcp_1",
server: "codex_app",
tool: "list_projects",
arguments: { limit: 5 },
result: { content: [{ type: "text", text: "[]" }] },
status: "completed",
},
},
},
{
timestamp: "2026-06-03T12:00:03.000Z",
type: "event_msg",
payload: { type: "task_complete", turn_id: "t" },
},
];
const { turns } = parseSession(lines);
const tools = turns[0].steps.flatMap((s) => s.toolCalls);
expect(tools).toHaveLength(1);
expect(tools[0].name).toBe("codex_app.list_projects");
expect(tools[0].mcp).toEqual({ server: "codex_app", tool: "list_projects" });
expect(tools[0].args).toEqual({ limit: 5 });
expect(tools[0].output).toEqual({ content: [{ type: "text", text: "[]" }] });
});

it("enriches a model-visible call from a completed McpToolCall item without duplicating it", () => {
const lines: RolloutLine[] = [
{ timestamp: "2026-06-03T12:00:00.000Z", type: "session_meta", payload: { id: "s" } },
{
timestamp: "2026-06-03T12:00:01.000Z",
type: "event_msg",
payload: { type: "task_started", turn_id: "t" },
},
{
timestamp: "2026-06-03T12:00:02.000Z",
type: "response_item",
payload: {
type: "function_call",
call_id: "mcp_2",
name: "linear__create_issue",
arguments: '{"title":"bug"}',
},
},
{
timestamp: "2026-06-03T12:00:03.000Z",
type: "event_msg",
payload: {
type: "item_completed",
item: {
type: "McpToolCall",
id: "mcp_2",
server: "linear",
tool: "create_issue",
arguments: { title: "bug" },
result: { Err: "boom" },
status: "failed",
},
},
},
{
timestamp: "2026-06-03T12:00:04.000Z",
type: "event_msg",
payload: { type: "task_complete", turn_id: "t" },
},
];
const { turns } = parseSession(lines);
const tools = turns[0].steps.flatMap((s) => s.toolCalls);
expect(tools).toHaveLength(1);
expect(tools[0].mcp).toEqual({ server: "linear", tool: "create_issue" });
expect(tools[0].error).toBe("boom");
expect(tools[0].output).toBeUndefined();
});

it("merges a web_search_call item with a later web_search_end event", () => {
const lines: RolloutLine[] = [
{ timestamp: "2026-06-03T12:00:00.000Z", type: "session_meta", payload: { id: "s" } },
Expand Down