Implement the following plan:

Raft KV Store Emulation Plan

Context

Create a replicated KV store using Raft consensus, matching the semantics of multipaxos_kv: put fails if key exists, get returns value or error, delete fails if key missing. Client is given leader directly (no leader discovery). The create-emulation skill requires TOML-based configuration.

Architecture

Raft vs MultiPaxos mapping

Key Design Decisions

1. Single node actor type (node.gleam): All Raft nodes are the same type with roles Leader/Follower/Candidate
2. Simplified election at startup: Node 1 starts election immediately, wins (like multipaxos_kv's Phase 1 at init)
3. Synchronous replication: Leader calls followers with actor.call during request handling (same pattern as multipaxos_kv's Phase 2)
4. Commit notification: After majority ack, leader sends fire-and-forget CommitNotification to followers so they apply entries
5. TOML config: Read num_nodes and num_clients from config file

Message Flow

Client --[ClientPut/Get/Delete]--> Leader Node
  Leader appends entry to log (term, command)
  Leader --[AppendEntries(entries)]--> all Follower Nodes (synchronous calls)
  Leader waits for majority of success responses
  Leader advances commit_index, applies to local KV store
  Leader --[reply]--> Client
  Leader --[CommitNotification(commit_index)]--> all Followers (fire-and-forget)
  Followers apply committed entries to their local KV stores

File Structure

raft_kv/
  gleam.toml
  config.toml                    -- default config: num_nodes=5, num_clients=3
  src/
    raft_kv.gleam                -- main: read TOML config, start nodes, election, clients
    raft_kv/
      types.gleam                -- Command, OpResult, LogEntry (shared types)
      node.gleam                 -- Raft node actor (all roles)
      client.gleam               -- client (adapted from multipaxos_kv/client.gleam)
  test/
    raft_kv_test.gleam           -- basic test

Implementation Details

1. types.gleam - Shared types

• Command = Put/Get/Delete/Noop (same as multipaxos_kv/types.gleam)
• OpResult = OpOk | OpError (same as multipaxos_kv/types.gleam)
• LogEntry(term: Int, command: Command) - new for Raft

2. node.gleam - Raft node actor (most complex file)

State: - id, current_term, voted_for: Option(Int), role: Role - log: Dict(Int, LogEntry) - 1-indexed - commit_index, last_applied - peers: List(#(Int, Subject(Message))) - set after startup via SetPeers - store: Dict(String, String) - KV state machine - Leader-only: next_index: Dict(Int, Int), match_index: Dict(Int, Int)

Messages: - SetPeers(List(#(Int, Subject(Message)))) - configuration after startup - StartElection - trigger election (sent to node 1 by main) - RequestVote(term, candidate_id, last_log_index, last_log_term, reply_with) / VoteResponse - AppendEntries(term, leader_id, prev_log_index, prev_log_term, entries, leader_commit, reply_with) / AppendEntriesResponse - CommitNotification(leader_commit: Int) - fire-and-forget commit update - ClientPut/ClientGet/ClientDelete - same signatures as multipaxos_kv/leader.gleam

Key functions: - handle_start_election: Increment term, vote for self, call RequestVote on all peers, become leader on majority - handle_request_vote: Standard Raft voting logic (term check, log up-to-date check) - handle_append_entries: Check term, check prev_log match, append entries, update commit_index, apply - handle_client_request: (Leader only) Append to log, synchronous AppendEntries to peers, on majority: commit, apply, reply, broadcast CommitNotification - apply_committed: Apply entries from last_applied+1 to commit_index (same KV semantics as multipaxos_kv)

3. client.gleam - Adapted from multipaxos_kv/client.gleam

• Same structure: 5 random requests, keys ["a","b","c","d","e"]
• Calls node.put, node.get, node.delete instead of leader.*
• References Subject(node.Message) instead of Subject(leader.Message)

4. raft_kv.gleam - Main entry point

• Read config.toml for num_nodes (default 5) and num_clients (default 3)
• Start N nodes, send SetPeers to each with all other nodes
• Send StartElection to node 1, small sleep to let election complete
• Start clients targeting node 1
• Send Start to all clients, sleep 3s

5. config.toml

num_nodes = 5
num_clients = 3

Dependencies

gleam_stdlib, gleam_otp, gleam_erlang, tom, argv

Note: tom for TOML parsing. argv to optionally accept config file path as CLI arg.

Reusable patterns from multipaxos_kv

• apply_command logic from multipaxos_kv/leader.gleam:106-156 (KV semantics)
• apply_committed pattern from multipaxos_kv/replica.gleam:27-83 (sequential log application)
• Client structure from multipaxos_kv/client.gleam (nearly identical)
• Main wiring from multipaxos_kv/multipaxos_kv.gleam (start actors, connect, run)

Verification

1. gleam build - compiles without errors
2. gleam run - shows: nodes starting, election completing, clients issuing requests with Raft replication trace, followers applying committed entries
3. gleam format - code is formatted
4. KV semantics match: put rejects existing keys, delete rejects missing keys, get returns value or error

If you need specific details from before exiting plan mode (like exact code snippets, error messages, or content you generated), read the full transcript at: /Users/apanda/.claude/projects/-Users-apanda-code-agent-spec-code/b2f3cfa8-4232-4552-95f3-5eccc20c4847.jsonl

[Request interrupted by user for tool use]

The code does not seem to include heartbeats, nor an election timeout. Can you check if I am mistaken about this, and if so point me to where they are?

Can you record that this is the case in the readme file. Include your reasoning too.

Can you create a commit with all of this.

[Request interrupted by user for tool use]

Can you create jujutsu commit for all the work so far?

Can you create a skill to ensure that you always check whether the repository is using jujustsu (and using jj if that is the case) before trying to use git for any version control operations.

Can you also update the gleam-otp skill to include information about tom, which you used for TOML in the raft implementation.

Create a commit for all of these changes.

[Request interrupted by user for tool use]

Create a new commit containing the changes made to CLAUDE.md and skills.

Rebase so that zkstsqls is the poarent for commit ynorsnuo.

Switch Raft and the gleam-otp skill to use simplifile for file I/O rather than using Erlang's file module.

Create a separate commit for each of the two files you changed.