Leader Election Trace

This component logs the lifecycle of each agent's candidacy. Key states include:

• FOLLOWER: The agent is passive, awaiting a leader or election timeout.
• CANDIDATE: The agent has initiated an election by incrementing its term and requesting votes.
• LEADER: The agent has won the election and is now responsible for coordinating the group.

Transitions between these states, triggered by timeouts or received messages, are timestamped and form the core narrative of the trace.

This captures the RequestVote RPC protocol exchanges. For each election term, the trace records:

• Vote Requests: The candidate's request, including its term, log index, and log term.
• Vote Grants/Denials: Each follower's response, logged with the granting agent's ID and the reason for denial (e.g., stale term, less complete log).

This log is critical for diagnosing split votes and understanding why a particular candidate succeeded or failed.

A monotonically increasing term number is the logical clock of the election. The trace logs:

• Term Increments: When an agent detects a stale leader or times out, it starts a new term.
• Epoch Boundaries: All messages and state changes are tagged with the current term, creating a clear timeline of leadership eras.

This sequencing prevents the "split-brain" scenario by ensuring agents from older terms cannot disrupt the current consensus.

After an election, the leader must assert authority. This component traces:

• Heartbeat Emissions: Periodic empty AppendEntries RPCs sent by the leader to maintain its lease and prevent follower timeouts.
• Follower Acknowledgments: Responses to heartbeats, confirming the leader's legitimacy.
• Log Replication Entries: The leader's attempts to replicate its state machine commands, which also serve as implicit heartbeats.

A break in this flow, visible in the trace, is the primary signal of leader failure.

These are quantitative measures extracted from the trace:

• Election Timeout: The randomized interval each follower waits before becoming a candidate. The trace logs the configured range and actual trigger time.
• Time-to-Leadership: The duration from the first RequestVote to the first successful AppendEntries from the new leader.
• Heartbeat Intervals: The period between consecutive leader heartbeats.

Analyzing these metrics is key to tuning system responsiveness and stability.

The definitive moment in the trace where a candidate secures leadership. It logs:

• Vote Tally: The count of granted votes per candidate per term.
• Quorum Threshold: The minimum votes required (typically majority of members).
• Leader Declaration: The precise event where the candidate, upon reaching quorum, transitions to leader and commits its first log entry (often a no-op).

This signal is the ultimate source of truth for determining the legitimate leader for any given term.

A group of agents that periodically exchange 'I am alive' signals to monitor liveness. This is critical for leader election, as the failure detection mechanism often triggers a new election.

• Heartbeat intervals and timeout thresholds
• Network partition detection via missing heartbeats
• Leader liveness verification post-election Monitoring this cluster provides the foundational health signal for the distributed agent group.

The process of identifying agents that are behaving arbitrarily or maliciously, potentially sending conflicting information. In leader election, a Byzantine agent could:

• Vote for multiple candidates in the same round
• Send false 'leader elected' messages
• Observability signals include vote inconsistency logs and message signature verification failures. Detection is essential for safety-critical systems requiring robust consensus.

The collection of data on the acquisition, hold time, and release of locks that coordinate access to shared resources. After a leader is elected, it often uses a distributed lock to assert exclusive control. Key metrics include:

• Lock acquisition latency post-election
• Lock hold duration to monitor leader tenure
• Lock contention if multiple agents incorrectly believe they are leader This telemetry validates the leader's exclusive authority.

A record of the inputs, process, and final outcome when a group of agents engages in a structured protocol to reach a joint decision. A Leader Election Trace is a specialized type of collective decision log. It captures:

• The quorum of participating agents
• The decision rule (e.g., majority vote, highest ID)
• The final elected leader and term/epoch number This log serves as the immutable audit trail for the election event.

An alert or metric indicating that the communication network has split into two or more isolated subgroups of agents. This is a primary cause for split-brain scenarios in leader election, where multiple leaders may be elected in different partitions. Observability focuses on:

• Detecting bidirectional connectivity loss between agent subsets
• Monitoring for divergent election logs in different partitions
• Triggering automatic partition recovery procedures upon healing