Aggregate trace events

Background

The Tracer logs every meaningful action as a TraceEvent with an agent_id and an event type. tracer.summary() starts by counting events grouped by (agent_id, event):

counts = {}
for e in events:
    key = (e["agent_id"], e["event"])
    counts[key] = counts.get(key, 0) + 1

Problem statement

Implement trace_counts(events) returning the {(agent_id, event): count} dict.

Input

• events — list of event dicts, each with "agent_id" and "event" keys.

Output

Returns a dict mapping each (agent_id, event) tuple to its number of occurrences.

Examples

Example 1

Input:  [{"agent_id": "exec_1_0", "event": "llm_call"},
         {"agent_id": "exec_1_0", "event": "llm_call"},
         {"agent_id": "exec_1_0", "event": "search"}]
Output: {("exec_1_0", "llm_call"): 2, ("exec_1_0", "search"): 1}

Constraints

• Key by the (agent_id, event) tuple.
• Count occurrences; empty input → {}.

Notes

• This grouping is the backbone of the summary table — one row per (agent, event) pair.