Implement the following plan:
The project needs a new emulation that replicates the existing kv_store using MultiPaxos consensus. This demonstrates how a distributed consensus protocol can be used to replicate state across multiple nodes while preserving the same client-facing semantics (put fails if key exists, get returns value or error, delete fails if key missing). The client is given a Subject pointing to the leader directly (no leader discovery).
Three actor types + client:
kv_store/client.gleam but 5 requests, targeting leaderClient --[ClientPut/Get/Delete]--> Leader
Leader assigns slot N
Leader --[Accept(slot N, ballot, cmd)]--> all Acceptors (synchronous calls)
Leader waits for quorum of Accepted responses
Leader applies command to local KV store
Leader --[reply]--> Client
Leader --[Commit(slot N, cmd)]--> all Replicas
actor.call during request handling. Simple, correct, educational.multipaxos_kv/
gleam.toml
src/
multipaxos_kv.gleam -- main entry point
multipaxos_kv/
types.gleam -- shared types (Command, Ballot, OpResult)
acceptor.gleam -- Paxos acceptor actor
leader.gleam -- proposer + learner + KV state machine + client API
replica.gleam -- passive learner
client.gleam -- 5 random requests to leader
test/
multipaxos_kv_test.gleam -- basic test
cd /Users/apanda/code/agent-spec-code
gleam new --skip-git --skip-github multipaxos_kv
cd multipaxos_kv
gleam add gleam_otp gleam_erlang argv
types.gleam - Shared typesBallot(round: Int, leader_id: Int) with comparison functionCommand = Put(key, value) | Get(key) | Delete(key) | NoopOpResult = OpOk | OpError(reason: String)acceptor.gleam - Paxos acceptorid, promised_ballot: Option(Ballot), accepted: Dict(Int, #(Ballot, Command)), selfPrepare(ballot, reply_with), Accept(slot, ballot, command, reply_with)Promise(accepted_entries) | PrepareRejected(highest), Accepted(slot) | AcceptRejected(slot, highest)leader.gleam - Core logic (most complex file)id, ballot, acceptors, replicas, quorum_size, next_slot, log: Dict(Int, Command), store: Dict(String, String), last_applied, selfClientPut(key, value, reply_with), ClientGet(key, reply_with), ClientDelete(key, reply_with) - same signatures as kv_store/serverput(leader, key, value), get(leader, key), delete(leader, key) matching kv_store/server signatureskv_store/server.gleam (put rejects existing keys, delete rejects missing keys)replica.gleam - Passive learnerid, log: Dict(Int, Command), store: Dict(String, String), last_applied, selfCommit(slot: Int, command: Command)client.gleam - Adapted from kv_storekv_store/client.gleamSubject(leader.Message) instead of Subject(server.Message)leader.put, leader.get (and optionally leader.delete)multipaxos_kv.gleam - Main/Users/apanda/code/agent-spec-code/kv_store/src/kv_store/server.gleam - KV semantics to replicate/Users/apanda/code/agent-spec-code/kv_store/src/kv_store/client.gleam - Client pattern to adapt/Users/apanda/code/agent-spec-code/kv_store/src/kv_store.gleam - Main wiring pattern/Users/apanda/code/agent-spec-code/.claude/skills/gleam-otp.md - Actor patternsgleam build - should compile without errorsgleam run - should show:gleam format - ensure code is formattedIf 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/7f5e4a48-7a64-493f-ad71-afbc3a310b33.jsonl
{
"type": "tool_reference",
"tool_name": "Read"
}{
"type": "tool_reference",
"tool_name": "Write"
}{
"type": "tool_reference",
"tool_name": "Edit"
}{
"type": "tool_reference",
"tool_name": "Bash"
}{
"type": "tool_reference",
"tool_name": "Glob"
}{
"type": "tool_reference",
"tool_name": "Grep"
}{
"type": "tool_reference",
"tool_name": "Agent"
} 1→# Gleam OTP Development
2→
3→## Metadata
4→name: Gleam OTP Development
5→description: This is a skill to help with developing Gleam OTP applications.
6→
7→## Creating a Gleam project
8→
9→```sh
10→ gleam new --skip-git --skip-github <project name> # Create a project. Project name can only contain alphanumeric characters and `_`
11→ cd <project name> # Change directory into the project
12→ gleam add gleam_otp # Add gleam_otp as a dependency
13→ gleam add gleam_erlang # Add gleam_erlang as a dependency.
14→```
15→
16→## Build Commands
17→
18→```sh
19→gleam build # Compile the project
20→gleam run # Run the project
21→gleam test # Run all tests
22→gleam add <pkg> # Add a dependency
23→gleam format # Format code
24→```
25→
26→## Actor Pattern with gleam_otp
27→
28→### Basic Actor Structure
29→
30→```gleam
31→import gleam/otp/actor
32→import gleam/erlang/process.{type Subject}
33→
34→// 1. Define state type
35→pub type State {
36→ State(value: Int, self: Subject(Message))
37→}
38→
39→// 2. Define message type
40→pub type Message {
41→ Set(value: Int) // Fire-and-forget
42→ Get(reply_with: Subject(Int)) // Request-response
43→}
44→
45→// 3. Implement handler
46→fn handle_message(state: State, message: Message) -> actor.Next(State, Message) {
47→ case message {
48→ Set(value) -> actor.continue(State(..state, value: value))
49→ Get(client) -> {
50→ process.send(client, state.value)
51→ actor.continue(state)
52→ }
53→ }
54→}
55→
56→// 4. Start function
57→pub fn start() -> Result(Subject(Message), actor.StartError) {
58→ actor.new_with_initialiser(1000, fn(self) {
59→ actor.initialised(State(value: 0, self: self))
60→ |> actor.returning(self)
61→ |> Ok
62→ })
63→ |> actor.on_message(handle_message)
64→ |> actor.start
65→ |> result.map(fn(started) { started.data })
66→}
67→```
68→
69→### Key Patterns
70→
71→**Fire-and-forget message:**
72→```gleam
73→pub fn set(subject: Subject(Message), value: Int) -> Nil {
74→ actor.send(subject, Set(value))
75→}
76→```
77→
78→**Request-response (blocking call):**
79→```gleam
80→pub fn get(subject: Subject(Message)) -> Int {
81→ actor.call(subject, 1000, Get) // 1000ms timeout
82→}
83→```
84→
85→**Self-messaging (for periodic tasks):**
86→```gleam
87→// In initialiser or handler:
88→process.send_after(state.self, 100, Sync) // Send Sync message after 100ms
89→```
90→
91→**Capturing self reference:**
92→Use `actor.new_with_initialiser` instead of `actor.new` to get access to the actor's own Subject in the initialiser callback.
93→
94→### Handler Return Values
95→
96→- `actor.continue(new_state)` - Keep running with new state
97→- `actor.stop()` - Stop the actor gracefully
98→
99→### Common Imports
100→
101→```gleam
102→import gleam/otp/actor
103→import gleam/erlang/process.{type Subject}
104→import gleam/result
105→import gleam/list
106→import gleam/int
107→import gleam/io
108→```
109→
110→## Testing
111→
112→Test functions must end with `_test` suffix:
113→
114→```gleam
115→import gleeunit
116→
117→pub fn main() -> Nil {
118→ gleeunit.main()
119→}
120→
121→pub fn my_feature_test() {
122→ assert some_condition == True
123→}
124→```
125→
126→## Common Patterns in This Codebase
127→
128→### Peer-to-peer Synchronization
129→
130→Servers maintain a list of peers and periodically broadcast their state:
131→
132→```gleam
133→Sync -> {
134→ list.each(state.peers, fn(peer) {
135→ process.send(peer, Set(state.value))
136→ })
137→ process.send_after(state.self, 100, Sync)
138→ actor.continue(state)
139→}
140→```
141→
142→### Convergence Check
143→
144→Poll until all actors have the same value:
145→
146→```gleam
147→fn wait_for_convergence(servers: List(Subject(Message))) -> Nil {
148→ let values = list.map(servers, get)
149→ case values {
150→ [first, ..rest] -> {
151→ let all_same = list.all(rest, fn(v) { v == first })
152→ case all_same && first > 0 {
153→ True -> io.println("Converged!")
154→ False -> {
155→ process.sleep(100)
156→ wait_for_convergence(servers)
157→ }
158→ }
159→ }
160→ [] -> Nil
161→ }
162→}
163→```
164→
165→## Gleam Syntax Quick Reference
166→
167→**Pattern matching:**
168→```gleam
169→case value {
170→ Some(x) -> x
171→ None -> 0
172→}
173→```
174→
175→**Record update:**
176→```gleam
177→State(..state, value: new_value)
178→```
179→
180→**Pipe operator:**
181→```gleam
182→value
183→|> transform1
184→|> transform2
185→```
186→
187→**Assert (panics on failure):**
188→```gleam
189→let assert Ok(result) = maybe_fails()
190→```
191→
192→**List operations:**
193→```gleam
194→list.map(items, fn(x) { x + 1 })
195→list.each(items, fn(x) { io.println(x) })
196→list.all(items, fn(x) { x > 0 })
197→list.flat_map(items, fn(x) { [x, x] })
198→```
199→{
"file_path": "/Users/apanda/code/agent-spec-code/kv_store/src/kv_store/server.gleam"
} 1→import gleam/dict.{type Dict}
2→import gleam/erlang/process.{type Subject}
3→import gleam/io
4→import gleam/otp/actor
5→import gleam/result
6→
7→/// The server's state: a dictionary mapping string keys to string values.
8→pub type State {
9→ State(store: Dict(String, String), self: Subject(Message))
10→}
11→
12→/// Result type for operations that can succeed or fail with a reason.
13→pub type OpResult {
14→ OpOk
15→ OpError(reason: String)
16→}
17→
18→/// Messages the KV server handles.
19→pub type Message {
20→ /// Insert a new key-value pair. Fails if the key already exists.
21→ Put(key: String, value: String, reply_with: Subject(OpResult))
22→ /// Retrieve the value for a key. Returns Ok(value) or Error if not found.
23→ Get(key: String, reply_with: Subject(Result(String, String)))
24→ /// Delete a key. Returns OpOk or OpError if the key doesn't exist.
25→ Delete(key: String, reply_with: Subject(OpResult))
26→}
27→
28→/// Handle incoming messages to the KV server.
29→fn handle_message(state: State, message: Message) -> actor.Next(State, Message) {
30→ case message {
31→ Put(key, value, reply_with) -> {
32→ case dict.has_key(state.store, key) {
33→ True -> {
34→ // Key already exists — reject the put
35→ io.println("[server] PUT \"" <> key <> "\" -> REJECTED (key exists)")
36→ process.send(reply_with, OpError("key already exists: " <> key))
37→ actor.continue(state)
38→ }
39→ False -> {
40→ // Insert the new key-value pair
41→ io.println(
42→ "[server] PUT \"" <> key <> "\" = \"" <> value <> "\" -> OK",
43→ )
44→ let new_store = dict.insert(state.store, key, value)
45→ process.send(reply_with, OpOk)
46→ actor.continue(State(..state, store: new_store))
47→ }
48→ }
49→ }
50→
51→ Get(key, reply_with) -> {
52→ case dict.get(state.store, key) {
53→ Ok(value) -> {
54→ io.println("[server] GET \"" <> key <> "\" -> \"" <> value <> "\"")
55→ process.send(reply_with, Ok(value))
56→ }
57→ Error(_) -> {
58→ io.println("[server] GET \"" <> key <> "\" -> NOT FOUND")
59→ process.send(reply_with, Error("key not found: " <> key))
60→ }
61→ }
62→ actor.continue(state)
63→ }
64→
65→ Delete(key, reply_with) -> {
66→ case dict.has_key(state.store, key) {
67→ True -> {
68→ io.println("[server] DELETE \"" <> key <> "\" -> OK")
69→ let new_store = dict.delete(state.store, key)
70→ process.send(reply_with, OpOk)
71→ actor.continue(State(..state, store: new_store))
72→ }
73→ False -> {
74→ io.println("[server] DELETE \"" <> key <> "\" -> NOT FOUND")
75→ process.send(reply_with, OpError("key not found: " <> key))
76→ actor.continue(state)
77→ }
78→ }
79→ }
80→ }
81→}
82→
83→/// Start a new KV server actor with an empty store.
84→pub fn start() -> Result(Subject(Message), actor.StartError) {
85→ actor.new_with_initialiser(1000, fn(self) {
86→ let state = State(store: dict.new(), self: self)
87→ actor.initialised(state)
88→ |> actor.returning(self)
89→ |> Ok
90→ })
91→ |> actor.on_message(handle_message)
92→ |> actor.start
93→ |> result.map(fn(started) { started.data })
94→}
95→
96→/// Put a key-value pair into the store. Returns an error if the key exists.
97→pub fn put(server: Subject(Message), key: String, value: String) -> OpResult {
98→ actor.call(server, 1000, Put(key, value, _))
99→}
100→
101→/// Get the value for a key. Returns Error if the key doesn't exist.
102→pub fn get(server: Subject(Message), key: String) -> Result(String, String) {
103→ actor.call(server, 1000, Get(key, _))
104→}
105→
106→/// Delete a key from the store. Returns an error if the key doesn't exist.
107→pub fn delete(server: Subject(Message), key: String) -> OpResult {
108→ actor.call(server, 1000, Delete(key, _))
109→}
110→{
"file_path": "/Users/apanda/code/agent-spec-code/kv_store/src/kv_store/client.gleam"
} 1→import gleam/erlang/process.{type Subject}
2→import gleam/int
3→import gleam/io
4→import gleam/otp/actor
5→import gleam/result
6→import kv_store/server
7→
8→/// Client state: tracks the server to talk to, remaining requests, and self.
9→pub type State {
10→ State(server: Subject(server.Message), remaining: Int, self: Subject(Message))
11→}
12→
13→/// Messages the client responds to.
14→pub type Message {
15→ /// Kick off the client's request loop.
16→ Start
17→ /// Internal message to continue sending the next request.
18→ Continue
19→}
20→
21→/// A small pool of keys the client randomly picks from, keeping collisions
22→/// likely so we exercise the "key already exists" and "key not found" paths.
23→const keys = #("a", "b", "c", "d", "e")
24→
25→/// Pick a random key from the pool.
26→fn random_key() -> String {
27→ case int.random(5) {
28→ 0 -> keys.0
29→ 1 -> keys.1
30→ 2 -> keys.2
31→ 3 -> keys.3
32→ _ -> keys.4
33→ }
34→}
35→
36→/// Pick a random value.
37→fn random_value() -> String {
38→ "val_" <> int.to_string(int.random(100))
39→}
40→
41→/// Handle incoming messages for the client actor.
42→fn handle_message(state: State, message: Message) -> actor.Next(State, Message) {
43→ case message {
44→ Start -> {
45→ io.println("[client] Starting — will send 10 requests")
46→ send_next_request(state)
47→ }
48→ Continue -> {
49→ send_next_request(state)
50→ }
51→ }
52→}
53→
54→/// Send the next random request (get or put) to the server, then schedule
55→/// a Continue message so the actor processes the next one.
56→fn send_next_request(state: State) -> actor.Next(State, Message) {
57→ case state.remaining {
58→ 0 -> {
59→ io.println("[client] Finished all 10 requests")
60→ actor.stop()
61→ }
62→ n -> {
63→ // Randomly choose between get (0) and put (1)
64→ case int.random(2) {
65→ 0 -> {
66→ let key = random_key()
67→ case server.get(state.server, key) {
68→ Ok(value) ->
69→ io.println(
70→ "[client] GET \"" <> key <> "\" -> \"" <> value <> "\"",
71→ )
72→ Error(reason) ->
73→ io.println("[client] GET \"" <> key <> "\" -> " <> reason)
74→ }
75→ }
76→ _ -> {
77→ let key = random_key()
78→ let value = random_value()
79→ case server.put(state.server, key, value) {
80→ server.OpOk ->
81→ io.println(
82→ "[client] PUT \"" <> key <> "\" = \"" <> value <> "\" -> OK",
83→ )
84→ server.OpError(reason) ->
85→ io.println(
86→ "[client] PUT \""
87→ <> key
88→ <> "\" = \""
89→ <> value
90→ <> "\" -> "
91→ <> reason,
92→ )
93→ }
94→ }
95→ }
96→
97→ // Schedule next request
98→ process.send(state.self, Continue)
99→ actor.continue(State(..state, remaining: n - 1))
100→ }
101→ }
102→}
103→
104→/// Start a client actor that will send 10 random requests to the given server.
105→pub fn start(
106→ server_subject: Subject(server.Message),
107→) -> Result(Subject(Message), actor.StartError) {
108→ actor.new_with_initialiser(1000, fn(self) {
109→ let state = State(server: server_subject, remaining: 10, self: self)
110→ actor.initialised(state)
111→ |> actor.returning(self)
112→ |> Ok
113→ })
114→ |> actor.on_message(handle_message)
115→ |> actor.start
116→ |> result.map(fn(started) { started.data })
117→}
118→ 1→import argv
2→import gleam/erlang/process
3→import gleam/int
4→import gleam/io
5→import gleam/list
6→import kv_store/client
7→import kv_store/server
8→
9→pub fn main() -> Nil {
10→ // Parse number of clients from command-line args (default: 3)
11→ let num_clients = case argv.load().arguments {
12→ [n_str, ..] -> {
13→ case int.parse(n_str) {
14→ Ok(n) if n > 0 -> n
15→ _ -> {
16→ io.println("Usage: gleam run -- <num_clients>")
17→ panic as "num_clients must be a positive integer"
18→ }
19→ }
20→ }
21→ [] -> 3
22→ }
23→
24→ // Start the KV server
25→ let assert Ok(kv_server) = server.start()
26→ io.println("Started KV server")
27→
28→ // Start the requested number of clients, each pointing at the same server
29→ let clients =
30→ list.range(1, num_clients)
31→ |> list.map(fn(i) {
32→ let assert Ok(c) = client.start(kv_server)
33→ io.println("Started client " <> int.to_string(i))
34→ c
35→ })
36→
37→ // Tell each client to begin sending requests
38→ list.each(clients, fn(c) { process.send(c, client.Start) })
39→ io.println("All " <> int.to_string(num_clients) <> " clients started")
40→
41→ // Wait for clients to finish their 10 requests each
42→ process.sleep(2000)
43→ io.println("Done")
44→}
45→{
"file_path": "/Users/apanda/code/agent-spec-code/.claude/skills/create-emulation.md"
} 1→## Metadata
2→name: Creating a distributed system emulation
3→description: This is a recipe for how to build a distributed system emulation in Gleam given a human description.
4→
5→
6→## Overview
7→In this environment we use Gleam for emulation. The goal is to produce a version that can be executed and help explain how the protocol (i.e., the algorithm implemented by the system) runs.
8→
9→Each type of process (or node or server, I tend to use the same word for all of them) is implemented as a Gleam actor. The Gleam OTP skill that accompanies this can help write the code. Do not try to optimize the code, but be sure to use comments to document the logic of each actor, and use print statements to record the execution of each actor.
10→
11→Once code for all types of processes has been written, change the main function to take a configuration file (in TOML) that specifies how many nodes of each type to start and then runs them to produce an execution schedule.
12→
13→Finally, use the appropriate version control system to add a commit for the emulation.
14→
15→## Writing a new emulation
16→
17→Use instructions from the gleam-otp skill.
18→
19→## Version Control
20→
21→Check if the root directory contains a `.jj` directory. If so, the project is managed using Jujutsu, and the accompanying jujutsu skill to manage things.
22→
23→If on the other hand the root directory contains a `.git` directory (but no `.jj` directory) use git.
24→gleam new --skip-git --skip-github multipaxos_kv && cd multipaxos_kv && gleam add gleam_otp gleam_erlang argv
Your Gleam project multipaxos_kv has been successfully created.
The project can be compiled and tested by running these commands:
cd multipaxos_kv
gleam test
Resolving versions
Downloading packages
Downloaded 5 packages in 0.05s
Added argv v1.0.2
Added gleam_erlang v1.3.0
Added gleam_otp v1.2.0
Added gleam_stdlib v0.70.0
Added gleeunit v1.9.0mkdir -p /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv
import gleam/order.{type Order}
/// A Paxos ballot number, consisting of a round and leader ID.
/// Higher round wins; ties broken by leader_id.
pub type Ballot {
Ballot(round: Int, leader_id: Int)
}
/// Compare two ballots. Higher round wins; ties broken by leader_id.
pub fn compare_ballots(a: Ballot, b: Ballot) -> Order {
case a.round == b.round {
True -> order.compare(a.leader_id, b.leader_id)
False -> order.compare(a.round, b.round)
}
}
/// A command to be replicated through Paxos.
pub type Command {
Put(key: String, value: String)
Get(key: String)
Delete(key: String)
Noop
}
/// Result of applying a command to the KV store.
pub type OpResult {
OpOk
OpError(reason: String)
}
File created successfully at: /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv/types.gleam
import gleam/dict.{type Dict}
import gleam/erlang/process.{type Subject}
import gleam/int
import gleam/io
import gleam/order
import gleam/otp/actor
import gleam/result
import multipaxos_kv/types.{type Ballot, type Command}
/// Acceptor state
pub type State {
State(
id: Int,
promised_ballot: Ballot,
accepted: Dict(Int, #(Ballot, Command)),
self: Subject(Message),
)
}
/// Response to a Prepare request
pub type PrepareResponse {
/// Promise not to accept lower ballots; includes previously accepted entries
Promise(accepted: Dict(Int, #(Ballot, Command)))
/// Rejected because a higher ballot was already promised
PrepareRejected(highest: Ballot)
}
/// Response to an Accept request
pub type AcceptResponse {
/// Successfully accepted the value for this slot
Accepted(slot: Int)
/// Rejected because a higher ballot was already promised
AcceptRejected(slot: Int, highest: Ballot)
}
/// Messages the acceptor handles
pub type Message {
/// Phase 1: Prepare request from a proposer
Prepare(ballot: Ballot, reply_with: Subject(PrepareResponse))
/// Phase 2: Accept request from a proposer
Accept(
slot: Int,
ballot: Ballot,
command: Command,
reply_with: Subject(AcceptResponse),
)
}
/// Handle incoming messages
fn handle_message(state: State, message: Message) -> actor.Next(State, Message) {
let id_str = int.to_string(state.id)
case message {
Prepare(ballot, reply_with) -> {
// Accept if ballot >= promised_ballot
case types.compare_ballots(ballot, state.promised_ballot) {
order.Lt -> {
io.println(
"[acceptor "
<> id_str
<> "] PREPARE rejected (higher ballot promised)",
)
process.send(reply_with, PrepareRejected(state.promised_ballot))
actor.continue(state)
}
_ -> {
io.println(
"[acceptor "
<> id_str
<> "] PREPARE accepted, promising ballot ("
<> int.to_string(ballot.round)
<> ","
<> int.to_string(ballot.leader_id)
<> ")",
)
process.send(reply_with, Promise(state.accepted))
actor.continue(State(..state, promised_ballot: ballot))
}
}
}
Accept(slot, ballot, command, reply_with) -> {
// Accept if ballot >= promised_ballot
case types.compare_ballots(ballot, state.promised_ballot) {
order.Lt -> {
io.println(
"[acceptor "
<> id_str
<> "] ACCEPT rejected for slot "
<> int.to_string(slot),
)
process.send(
reply_with,
AcceptRejected(slot, state.promised_ballot),
)
actor.continue(state)
}
_ -> {
io.println(
"[acceptor "
<> id_str
<> "] ACCEPT for slot "
<> int.to_string(slot)
<> " -> accepted",
)
let new_accepted =
dict.insert(state.accepted, slot, #(ballot, command))
process.send(reply_with, Accepted(slot))
actor.continue(
State(..state, promised_ballot: ballot, accepted: new_accepted),
)
}
}
}
}
}
/// Start an acceptor actor with the given ID
pub fn start(id: Int) -> Result(Subject(Message), actor.StartError) {
actor.new_with_initialiser(1000, fn(self) {
io.println("[acceptor " <> int.to_string(id) <> "] Starting")
let state =
State(
id: id,
promised_ballot: types.Ballot(round: 0, leader_id: 0),
accepted: dict.new(),
self: self,
)
actor.initialised(state)
|> actor.returning(self)
|> Ok
})
|> actor.on_message(handle_message)
|> actor.start
|> result.map(fn(started) { started.data })
}
File created successfully at: /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv/acceptor.gleam
import gleam/dict.{type Dict}
import gleam/erlang/process.{type Subject}
import gleam/int
import gleam/io
import gleam/otp/actor
import gleam/result
import multipaxos_kv/types.{type Command}
/// Replica state: passive learner that applies committed commands
pub type State {
State(
id: Int,
log: Dict(Int, Command),
store: Dict(String, String),
last_applied: Int,
self: Subject(Message),
)
}
/// Messages the replica handles
pub type Message {
/// A committed command from the leader
Commit(slot: Int, command: Command)
}
/// Apply commands from the log in order, starting from last_applied + 1
fn apply_committed(state: State) -> State {
let next_slot = state.last_applied + 1
case dict.get(state.log, next_slot) {
Error(_) -> state
Ok(command) -> {
let id_str = int.to_string(state.id)
let slot_str = int.to_string(next_slot)
let new_store = case command {
types.Put(key, value) -> {
io.println(
"[replica "
<> id_str
<> "] slot "
<> slot_str
<> ": PUT \""
<> key
<> "\" = \""
<> value
<> "\"",
)
dict.insert(state.store, key, value)
}
types.Get(key) -> {
io.println(
"[replica "
<> id_str
<> "] slot "
<> slot_str
<> ": GET \""
<> key
<> "\"",
)
state.store
}
types.Delete(key) -> {
io.println(
"[replica "
<> id_str
<> "] slot "
<> slot_str
<> ": DELETE \""
<> key
<> "\"",
)
dict.delete(state.store, key)
}
types.Noop -> {
io.println(
"[replica " <> id_str <> "] slot " <> slot_str <> ": NOOP",
)
state.store
}
}
let new_state =
State(..state, store: new_store, last_applied: next_slot)
// Try to apply the next slot too (in case commits arrived out of order)
apply_committed(new_state)
}
}
}
/// Handle incoming messages
fn handle_message(state: State, message: Message) -> actor.Next(State, Message) {
case message {
Commit(slot, command) -> {
let new_log = dict.insert(state.log, slot, command)
let new_state = apply_committed(State(..state, log: new_log))
actor.continue(new_state)
}
}
}
/// Start a replica actor with the given ID
pub fn start(id: Int) -> Result(Subject(Message), actor.StartError) {
actor.new_with_initialiser(1000, fn(self) {
io.println("[replica " <> int.to_string(id) <> "] Starting")
let state =
State(
id: id,
log: dict.new(),
store: dict.new(),
last_applied: 0,
self: self,
)
actor.initialised(state)
|> actor.returning(self)
|> Ok
})
|> actor.on_message(handle_message)
|> actor.start
|> result.map(fn(started) { started.data })
}
File created successfully at: /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv/replica.gleam
import gleam/dict.{type Dict}
import gleam/erlang/process.{type Subject}
import gleam/int
import gleam/io
import gleam/list
import gleam/otp/actor
import gleam/result
import multipaxos_kv/acceptor
import multipaxos_kv/replica
import multipaxos_kv/types.{type Ballot, type Command}
/// Leader state: proposer + learner + KV state machine
pub type State {
State(
id: Int,
ballot: Ballot,
acceptors: List(Subject(acceptor.Message)),
replicas: List(Subject(replica.Message)),
quorum_size: Int,
next_slot: Int,
log: Dict(Int, Command),
store: Dict(String, String),
last_applied: Int,
self: Subject(Message),
)
}
/// Messages the leader handles
pub type Message {
/// Client request to insert a key-value pair
ClientPut(key: String, value: String, reply_with: Subject(types.OpResult))
/// Client request to get a value by key
ClientGet(key: String, reply_with: Subject(Result(String, String)))
/// Client request to delete a key
ClientDelete(key: String, reply_with: Subject(types.OpResult))
}
/// Run Phase 1 (prepare) against all acceptors. Panics if quorum not reached.
fn run_phase1(
ballot: Ballot,
acceptors: List(Subject(acceptor.Message)),
quorum_size: Int,
) -> Nil {
io.println(
"[leader] Phase 1: sending Prepare("
<> int.to_string(ballot.round)
<> ","
<> int.to_string(ballot.leader_id)
<> ") to "
<> int.to_string(list.length(acceptors))
<> " acceptors",
)
let promises =
list.filter_map(acceptors, fn(acc) {
let response = actor.call(acc, 1000, acceptor.Prepare(ballot, _))
case response {
acceptor.Promise(_accepted) -> Ok(Nil)
acceptor.PrepareRejected(_) -> Error(Nil)
}
})
let num_promises = list.length(promises)
io.println(
"[leader] Phase 1 complete: "
<> int.to_string(num_promises)
<> " promises received (need "
<> int.to_string(quorum_size)
<> ")",
)
case num_promises >= quorum_size {
True -> Nil
False -> panic as "Failed to get quorum in Phase 1"
}
}
/// Run Phase 2 (accept) for a single slot. Returns True if quorum accepted.
fn run_phase2(
slot: Int,
ballot: Ballot,
command: Command,
acceptors: List(Subject(acceptor.Message)),
quorum_size: Int,
) -> Bool {
let accepted_count =
list.filter_map(acceptors, fn(acc) {
let response =
actor.call(acc, 1000, acceptor.Accept(slot, ballot, command, _))
case response {
acceptor.Accepted(_) -> Ok(Nil)
acceptor.AcceptRejected(_, _) -> Error(Nil)
}
})
|> list.length
io.println(
"[leader] Phase 2 for slot "
<> int.to_string(slot)
<> ": "
<> int.to_string(accepted_count)
<> "/"
<> int.to_string(quorum_size)
<> " accepted",
)
accepted_count >= quorum_size
}
/// Apply a command to the KV store, returning the result and updated store
fn apply_command(
command: Command,
store: Dict(String, String),
) -> #(Dict(String, String), Command, types.OpResult, Result(String, String)) {
case command {
types.Put(key, value) -> {
case dict.has_key(store, key) {
True -> {
io.println(
"[leader] PUT \"" <> key <> "\" -> REJECTED (key exists)",
)
#(store, command, types.OpError("key already exists: " <> key), Error(
"",
))
}
False -> {
io.println(
"[leader] PUT \"" <> key <> "\" = \"" <> value <> "\" -> OK",
)
#(dict.insert(store, key, value), command, types.OpOk, Error(""))
}
}
}
types.Get(key) -> {
case dict.get(store, key) {
Ok(value) -> {
io.println(
"[leader] GET \"" <> key <> "\" -> \"" <> value <> "\"",
)
#(store, command, types.OpOk, Ok(value))
}
Error(_) -> {
io.println("[leader] GET \"" <> key <> "\" -> NOT FOUND")
#(store, command, types.OpOk, Error("key not found: " <> key))
}
}
}
types.Delete(key) -> {
case dict.has_key(store, key) {
True -> {
io.println("[leader] DELETE \"" <> key <> "\" -> OK")
#(dict.delete(store, key), command, types.OpOk, Error(""))
}
False -> {
io.println("[leader] DELETE \"" <> key <> "\" -> NOT FOUND")
#(
store,
command,
types.OpError("key not found: " <> key),
Error(""),
)
}
}
}
types.Noop -> #(store, command, types.OpOk, Error(""))
}
}
/// Broadcast a committed command to all replicas
fn broadcast_commit(
replicas: List(Subject(replica.Message)),
slot: Int,
command: Command,
) -> Nil {
list.each(replicas, fn(r) { process.send(r, replica.Commit(slot, command)) })
}
/// Handle a client request: assign slot, run Phase 2, apply, reply, broadcast
fn handle_client_request(
state: State,
command: Command,
reply_put: fn(types.OpResult) -> Nil,
reply_get: fn(Result(String, String)) -> Nil,
) -> actor.Next(State, Message) {
let slot = state.next_slot
io.println(
"[leader] Assigning slot " <> int.to_string(slot) <> " for client request",
)
// Run Phase 2 for this slot
let committed =
run_phase2(slot, state.ballot, command, state.acceptors, state.quorum_size)
case committed {
True -> {
// Apply to local KV store
let #(new_store, cmd, op_result, get_result) =
apply_command(command, state.store)
let new_log = dict.insert(state.log, slot, cmd)
// Reply to client
reply_put(op_result)
reply_get(get_result)
// Broadcast commit to replicas
broadcast_commit(state.replicas, slot, cmd)
actor.continue(
State(
..state,
next_slot: slot + 1,
log: new_log,
store: new_store,
last_applied: slot,
),
)
}
False -> {
io.println("[leader] Phase 2 FAILED for slot " <> int.to_string(slot))
reply_put(types.OpError("consensus failed"))
reply_get(Error("consensus failed"))
actor.continue(state)
}
}
}
/// Handle incoming messages
fn handle_message(state: State, message: Message) -> actor.Next(State, Message) {
case message {
ClientPut(key, value, reply_with) -> {
handle_client_request(
state,
types.Put(key, value),
fn(r) { process.send(reply_with, r) },
fn(_) { Nil },
)
}
ClientGet(key, reply_with) -> {
handle_client_request(
state,
types.Get(key),
fn(_) { Nil },
fn(r) { process.send(reply_with, r) },
)
}
ClientDelete(key, reply_with) -> {
handle_client_request(
state,
types.Delete(key),
fn(r) { process.send(reply_with, r) },
fn(_) { Nil },
)
}
}
}
/// Start a leader actor. Runs Phase 1 during initialization.
pub fn start(
id: Int,
acceptors: List(Subject(acceptor.Message)),
replicas: List(Subject(replica.Message)),
) -> Result(Subject(Message), actor.StartError) {
let ballot = types.Ballot(round: 1, leader_id: id)
let quorum_size = list.length(acceptors) / 2 + 1
actor.new_with_initialiser(5000, fn(self) {
io.println("[leader] Starting with id " <> int.to_string(id))
// Run Phase 1 to establish leadership
run_phase1(ballot, acceptors, quorum_size)
io.println("[leader] Phase 1 complete — leader established")
let state =
State(
id: id,
ballot: ballot,
acceptors: acceptors,
replicas: replicas,
quorum_size: quorum_size,
next_slot: 1,
log: dict.new(),
store: dict.new(),
last_applied: 0,
self: self,
)
actor.initialised(state)
|> actor.returning(self)
|> Ok
})
|> actor.on_message(handle_message)
|> actor.start
|> result.map(fn(started) { started.data })
}
/// Put a key-value pair. Returns error if the key already exists.
pub fn put(
leader: Subject(Message),
key: String,
value: String,
) -> types.OpResult {
actor.call(leader, 5000, ClientPut(key, value, _))
}
/// Get the value for a key. Returns Error if not found.
pub fn get(leader: Subject(Message), key: String) -> Result(String, String) {
actor.call(leader, 5000, ClientGet(key, _))
}
/// Delete a key. Returns error if the key doesn't exist.
pub fn delete(leader: Subject(Message), key: String) -> types.OpResult {
actor.call(leader, 5000, ClientDelete(key, _))
}
File created successfully at: /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv/leader.gleam
import gleam/erlang/process.{type Subject}
import gleam/int
import gleam/io
import gleam/otp/actor
import gleam/result
import multipaxos_kv/leader
import multipaxos_kv/types
/// Client state
pub type State {
State(
leader: Subject(leader.Message),
remaining: Int,
self: Subject(Message),
)
}
/// Messages the client responds to
pub type Message {
/// Kick off the client's request loop
Start
/// Internal message to continue sending the next request
Continue
}
/// A small pool of keys the client randomly picks from
const keys = #("a", "b", "c", "d", "e")
/// Pick a random key from the pool
fn random_key() -> String {
case int.random(5) {
0 -> keys.0
1 -> keys.1
2 -> keys.2
3 -> keys.3
_ -> keys.4
}
}
/// Pick a random value
fn random_value() -> String {
"val_" <> int.to_string(int.random(100))
}
/// Handle incoming messages
fn handle_message(state: State, message: Message) -> actor.Next(State, Message) {
case message {
Start -> {
io.println("[client] Starting — will send 5 requests")
send_next_request(state)
}
Continue -> {
send_next_request(state)
}
}
}
/// Send the next random request to the leader via Paxos
fn send_next_request(state: State) -> actor.Next(State, Message) {
case state.remaining {
0 -> {
io.println("[client] Finished all 5 requests")
actor.stop()
}
n -> {
// Randomly choose between get (0), put (1), and delete (2)
case int.random(3) {
0 -> {
let key = random_key()
case leader.get(state.leader, key) {
Ok(value) ->
io.println(
"[client] GET \"" <> key <> "\" -> \"" <> value <> "\"",
)
Error(reason) ->
io.println("[client] GET \"" <> key <> "\" -> " <> reason)
}
}
1 -> {
let key = random_key()
let value = random_value()
case leader.put(state.leader, key, value) {
types.OpOk ->
io.println(
"[client] PUT \"" <> key <> "\" = \"" <> value <> "\" -> OK",
)
types.OpError(reason) ->
io.println(
"[client] PUT \""
<> key
<> "\" = \""
<> value
<> "\" -> "
<> reason,
)
}
}
_ -> {
let key = random_key()
case leader.delete(state.leader, key) {
types.OpOk ->
io.println("[client] DELETE \"" <> key <> "\" -> OK")
types.OpError(reason) ->
io.println("[client] DELETE \"" <> key <> "\" -> " <> reason)
}
}
}
// Schedule next request
process.send(state.self, Continue)
actor.continue(State(..state, remaining: n - 1))
}
}
}
/// Start a client actor that will send 5 random requests to the leader
pub fn start(
leader_subject: Subject(leader.Message),
) -> Result(Subject(Message), actor.StartError) {
actor.new_with_initialiser(1000, fn(self) {
let state = State(leader: leader_subject, remaining: 5, self: self)
actor.initialised(state)
|> actor.returning(self)
|> Ok
})
|> actor.on_message(handle_message)
|> actor.start
|> result.map(fn(started) { started.data })
}
File created successfully at: /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv/client.gleam
import argv
import gleam/erlang/process
import gleam/int
import gleam/io
import gleam/list
import multipaxos_kv/acceptor
import multipaxos_kv/client
import multipaxos_kv/leader
import multipaxos_kv/replica
pub fn main() -> Nil {
// Parse number of clients from command-line args (default: 3)
let num_clients = case argv.load().arguments {
[n_str, ..] -> {
case int.parse(n_str) {
Ok(n) if n > 0 -> n
_ -> {
io.println("Usage: gleam run -- <num_clients>")
panic as "num_clients must be a positive integer"
}
}
}
[] -> 3
}
// Start 3 acceptors
let acceptors =
list.range(1, 3)
|> list.map(fn(i) {
let assert Ok(a) = acceptor.start(i)
io.println("Started acceptor " <> int.to_string(i))
a
})
// Start 2 replicas
let replicas =
list.range(1, 2)
|> list.map(fn(i) {
let assert Ok(r) = replica.start(i)
io.println("Started replica " <> int.to_string(i))
r
})
// Start the leader (runs Phase 1 during init)
let assert Ok(the_leader) = leader.start(1, acceptors, replicas)
io.println("Started leader")
// Start clients
let clients =
list.range(1, num_clients)
|> list.map(fn(i) {
let assert Ok(c) = client.start(the_leader)
io.println("Started client " <> int.to_string(i))
c
})
// Tell each client to begin sending requests
list.each(clients, fn(c) { process.send(c, client.Start) })
io.println(
"All " <> int.to_string(num_clients) <> " clients started sending requests",
)
// Wait for clients to finish
process.sleep(3000)
io.println("Done")
}
<tool_use_error>File has not been read yet. Read it first before writing to it.</tool_use_error>
import gleeunit
import multipaxos_kv/acceptor
import multipaxos_kv/leader
import multipaxos_kv/replica
import multipaxos_kv/types
pub fn main() -> Nil {
gleeunit.main()
}
pub fn leader_put_get_test() {
let assert Ok(a1) = acceptor.start(1)
let assert Ok(a2) = acceptor.start(2)
let assert Ok(a3) = acceptor.start(3)
let assert Ok(r1) = replica.start(1)
let assert Ok(l) = leader.start(1, [a1, a2, a3], [r1])
let assert types.OpOk = leader.put(l, "x", "hello")
let assert Ok("hello") = leader.get(l, "x")
let assert types.OpError(_) = leader.put(l, "x", "world")
let assert types.OpOk = leader.delete(l, "x")
let assert Error(_) = leader.get(l, "x")
let assert types.OpError(_) = leader.delete(l, "x")
}
<tool_use_error>File has not been read yet. Read it first before writing to it.</tool_use_error>
{
"file_path": "/Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv.gleam"
} 1→import gleam/io
2→
3→pub fn main() -> Nil {
4→ io.println("Hello from multipaxos_kv!")
5→}
6→{
"file_path": "/Users/apanda/code/agent-spec-code/multipaxos_kv/test/multipaxos_kv_test.gleam"
} 1→import gleeunit
2→
3→pub fn main() -> Nil {
4→ gleeunit.main()
5→}
6→
7→// gleeunit test functions end in `_test`
8→pub fn hello_world_test() {
9→ let name = "Joe"
10→ let greeting = "Hello, " <> name <> "!"
11→
12→ assert greeting == "Hello, Joe!"
13→}
14→import argv
import gleam/erlang/process
import gleam/int
import gleam/io
import gleam/list
import multipaxos_kv/acceptor
import multipaxos_kv/client
import multipaxos_kv/leader
import multipaxos_kv/replica
pub fn main() -> Nil {
// Parse number of clients from command-line args (default: 3)
let num_clients = case argv.load().arguments {
[n_str, ..] -> {
case int.parse(n_str) {
Ok(n) if n > 0 -> n
_ -> {
io.println("Usage: gleam run -- <num_clients>")
panic as "num_clients must be a positive integer"
}
}
}
[] -> 3
}
// Start 3 acceptors
let acceptors =
list.range(1, 3)
|> list.map(fn(i) {
let assert Ok(a) = acceptor.start(i)
io.println("Started acceptor " <> int.to_string(i))
a
})
// Start 2 replicas
let replicas =
list.range(1, 2)
|> list.map(fn(i) {
let assert Ok(r) = replica.start(i)
io.println("Started replica " <> int.to_string(i))
r
})
// Start the leader (runs Phase 1 during init)
let assert Ok(the_leader) = leader.start(1, acceptors, replicas)
io.println("Started leader")
// Start clients
let clients =
list.range(1, num_clients)
|> list.map(fn(i) {
let assert Ok(c) = client.start(the_leader)
io.println("Started client " <> int.to_string(i))
c
})
// Tell each client to begin sending requests
list.each(clients, fn(c) { process.send(c, client.Start) })
io.println(
"All " <> int.to_string(num_clients) <> " clients started sending requests",
)
// Wait for clients to finish
process.sleep(3000)
io.println("Done")
}
The file /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv.gleam has been updated successfully.
import gleeunit
import multipaxos_kv/acceptor
import multipaxos_kv/leader
import multipaxos_kv/replica
import multipaxos_kv/types
pub fn main() -> Nil {
gleeunit.main()
}
pub fn leader_put_get_test() {
let assert Ok(a1) = acceptor.start(1)
let assert Ok(a2) = acceptor.start(2)
let assert Ok(a3) = acceptor.start(3)
let assert Ok(r1) = replica.start(1)
let assert Ok(l) = leader.start(1, [a1, a2, a3], [r1])
let assert types.OpOk = leader.put(l, "x", "hello")
let assert Ok("hello") = leader.get(l, "x")
let assert types.OpError(_) = leader.put(l, "x", "world")
let assert types.OpOk = leader.delete(l, "x")
let assert Error(_) = leader.get(l, "x")
let assert types.OpError(_) = leader.delete(l, "x")
}
The file /Users/apanda/code/agent-spec-code/multipaxos_kv/test/multipaxos_kv_test.gleam has been updated successfully.
Exit code 1
Compiling argv
Compiling gleam_stdlib
Compiling gleam_erlang
Compiling gleam_otp
Compiling gleeunit
Compiling multipaxos_kv
error: Type mismatch
┌─ /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv/types.gleam:12:27
│
12 │ True -> order.compare(a.leader_id, b.leader_id)
│ ^^^^^^^^^^^
Expected type:
Order
Found type:
Int
error: Type mismatch
┌─ /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv/types.gleam:12:40
│
12 │ True -> order.compare(a.leader_id, b.leader_id)
│ ^^^^^^^^^^^
Expected type:
Order
Found type:
Int
error: Type mismatch
┌─ /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv/types.gleam:13:28
│
13 │ False -> order.compare(a.round, b.round)
│ ^^^^^^^
Expected type:
Order
Found type:
Int
error: Type mismatch
┌─ /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv/types.gleam:13:37
│
13 │ False -> order.compare(a.round, b.round)
│ ^^^^^^^
Expected type:
Order
Found type:
Intimport gleam/order.{type Order}
/// A Paxos ballot number, consisting of a round and leader ID.
/// Higher round wins; ties broken by leader_id.
pub type Ballot {
Ballot(round: Int, leader_id: Int)
}
/// Compare two ballots. Higher round wins; ties broken by leader_id.
pub fn compare_ballots(a: Ballot, b: Ballot) -> Order {
case a.round == b.round {
True -> order.compare(a.leader_id, b.leader_id)
False -> order.compare(a.round, b.round)
}
}import gleam/int
import gleam/order.{type Order}
/// A Paxos ballot number, consisting of a round and leader ID.
/// Higher round wins; ties broken by leader_id.
pub type Ballot {
Ballot(round: Int, leader_id: Int)
}
/// Compare two ballots. Higher round wins; ties broken by leader_id.
pub fn compare_ballots(a: Ballot, b: Ballot) -> Order {
case a.round == b.round {
True -> int.compare(a.leader_id, b.leader_id)
False -> int.compare(a.round, b.round)
}
}The file /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv/types.gleam has been updated successfully.
Compiling multipaxos_kv warning: Deprecated value used ┌─ /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv.gleam:28:10 │ 28 │ list.range(1, 3) │ ^^^^^ This value has been deprecated It was deprecated with this message: Use int.range instead warning: Deprecated value used ┌─ /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv.gleam:37:10 │ 37 │ list.range(1, 2) │ ^^^^^ This value has been deprecated It was deprecated with this message: Use int.range instead warning: Deprecated value used ┌─ /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv.gleam:50:10 │ 50 │ list.range(1, num_clients) │ ^^^^^ This value has been deprecated It was deprecated with this message: Use int.range instead Compiled in 0.36s
import gleam/list import multipaxos_kv/acceptor
import gleam/list import multipaxos_kv/acceptor
The file /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv.gleam has been updated successfully.
list.range(1, 3)
|> list.map(fn(i) {
let assert Ok(a) = acceptor.start(i)
io.println("Started acceptor " <> int.to_string(i))
a
})
// Start 2 replicas
let replicas =
list.range(1, 2)
|> list.map(fn(i) {
let assert Ok(r) = replica.start(i)
io.println("Started replica " <> int.to_string(i))
r
}) int.range(1, 3)
|> list.map(fn(i) {
let assert Ok(a) = acceptor.start(i)
io.println("Started acceptor " <> int.to_string(i))
a
})
// Start 2 replicas
let replicas =
int.range(1, 2)
|> list.map(fn(i) {
let assert Ok(r) = replica.start(i)
io.println("Started replica " <> int.to_string(i))
r
})The file /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv.gleam has been updated successfully.
list.range(1, num_clients)
int.range(1, num_clients)
The file /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv.gleam has been updated successfully.
Exit code 1 Compiling multipaxos_kv error: Incorrect arity ┌─ /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv.gleam:29:5 │ 29 │ int.range(1, 3) │ ^^^^^^^^^^^^^^^ Expected 4 arguments, got 2 This call accepts these additional labelled arguments: - run - with error: Incorrect arity ┌─ /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv.gleam:38:5 │ 38 │ int.range(1, 2) │ ^^^^^^^^^^^^^^^ Expected 4 arguments, got 2 This call accepts these additional labelled arguments: - run - with error: Incorrect arity ┌─ /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv.gleam:51:5 │ 51 │ int.range(1, num_clients) │ ^^^^^^^^^^^^^^^^^^^^^^^^^ Expected 4 arguments, got 2 This call accepts these additional labelled arguments: - run - with
grep -r "pub fn range" build/packages/gleam_stdlib/src/gleam/int.gleam 2>/dev/null | head -5
{
"pattern": "pub fn range",
"path": "/Users/apanda/code/agent-spec-code/multipaxos_kv/build/packages/gleam_stdlib/src/gleam/int.gleam",
"output_mode": "content",
"-A": 15
}800:pub fn range(
801- from start: Int,
802- to stop: Int,
803- with acc: acc,
804- run reducer: fn(acc, Int) -> acc,
805-) -> acc {
806- let increment = case start < stop {
807- True -> 1
808- False -> -1
809- }
810- range_loop(start, stop, increment, acc, reducer)
811-}
812-
813-fn range_loop(
814- current: Int,
815- stop: Int,New API is a fold-style. Let me revert to list.range since it still works (just deprecated).
int.range(
list.range(
The file /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv.gleam has been updated. All occurrences of 'int.range(' were successfully replaced with 'list.range('.Compiling multipaxos_kv warning: Deprecated value used ┌─ /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv.gleam:29:10 │ 29 │ list.range(1, 3) │ ^^^^^ This value has been deprecated It was deprecated with this message: Use int.range instead warning: Deprecated value used ┌─ /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv.gleam:38:10 │ 38 │ list.range(1, 2) │ ^^^^^ This value has been deprecated It was deprecated with this message: Use int.range instead warning: Deprecated value used ┌─ /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv.gleam:51:10 │ 51 │ list.range(1, num_clients) │ ^^^^^ This value has been deprecated It was deprecated with this message: Use int.range instead Compiled in 2.79s
{
"file_path": "/Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv.gleam"
} 1→import argv
2→import gleam/erlang/process
3→import gleam/int
4→import gleam/io
5→import gleam/list
6→import multipaxos_kv/acceptor
7→
8→import multipaxos_kv/client
9→import multipaxos_kv/leader
10→import multipaxos_kv/replica
11→
12→pub fn main() -> Nil {
13→ // Parse number of clients from command-line args (default: 3)
14→ let num_clients = case argv.load().arguments {
15→ [n_str, ..] -> {
16→ case int.parse(n_str) {
17→ Ok(n) if n > 0 -> n
18→ _ -> {
19→ io.println("Usage: gleam run -- <num_clients>")
20→ panic as "num_clients must be a positive integer"
21→ }
22→ }
23→ }
24→ [] -> 3
25→ }
26→
27→ // Start 3 acceptors
28→ let acceptors =
29→ list.range(1, 3)
30→ |> list.map(fn(i) {
31→ let assert Ok(a) = acceptor.start(i)
32→ io.println("Started acceptor " <> int.to_string(i))
33→ a
34→ })
35→
36→ // Start 2 replicas
37→ let replicas =
38→ list.range(1, 2)
39→ |> list.map(fn(i) {
40→ let assert Ok(r) = replica.start(i)
41→ io.println("Started replica " <> int.to_string(i))
42→ r
43→ })
44→
45→ // Start the leader (runs Phase 1 during init)
46→ let assert Ok(the_leader) = leader.start(1, acceptors, replicas)
47→ io.println("Started leader")
48→
49→ // Start clients
50→ let clients =
51→ list.range(1, num_clients)
52→ |> list.map(fn(i) {
53→ let assert Ok(c) = client.start(the_leader)
54→ io.println("Started client " <> int.to_string(i))
55→ c
56→ })
57→
58→ // Tell each client to begin sending requests
59→ list.each(clients, fn(c) { process.send(c, client.Start) })
60→ io.println(
61→ "All " <> int.to_string(num_clients) <> " clients started sending requests",
62→ )
63→
64→ // Wait for clients to finish
65→ process.sleep(3000)
66→ io.println("Done")
67→}
68→import argv
import gleam/erlang/process
import gleam/int
import gleam/io
import gleam/list
import multipaxos_kv/acceptor
import multipaxos_kv/client
import multipaxos_kv/leader
import multipaxos_kv/replica
/// Helper to create a list [1, 2, ..., n]
fn range_list(n: Int) -> List(Int) {
int.range(1, n, [], fn(acc, i) { [i, ..acc] })
|> list.reverse
}
pub fn main() -> Nil {
// Parse number of clients from command-line args (default: 3)
let num_clients = case argv.load().arguments {
[n_str, ..] -> {
case int.parse(n_str) {
Ok(n) if n > 0 -> n
_ -> {
io.println("Usage: gleam run -- <num_clients>")
panic as "num_clients must be a positive integer"
}
}
}
[] -> 3
}
// Start 3 acceptors
let acceptors =
range_list(3)
|> list.map(fn(i) {
let assert Ok(a) = acceptor.start(i)
io.println("Started acceptor " <> int.to_string(i))
a
})
// Start 2 replicas
let replicas =
range_list(2)
|> list.map(fn(i) {
let assert Ok(r) = replica.start(i)
io.println("Started replica " <> int.to_string(i))
r
})
// Start the leader (runs Phase 1 during init)
let assert Ok(the_leader) = leader.start(1, acceptors, replicas)
io.println("Started leader")
// Start clients
let clients =
range_list(num_clients)
|> list.map(fn(i) {
let assert Ok(c) = client.start(the_leader)
io.println("Started client " <> int.to_string(i))
c
})
// Tell each client to begin sending requests
list.each(clients, fn(c) { process.send(c, client.Start) })
io.println(
"All " <> int.to_string(num_clients) <> " clients started sending requests",
)
// Wait for clients to finish
process.sleep(3000)
io.println("Done")
}
The file /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv.gleam has been updated successfully.
Compiled in 0.02s
Running multipaxos_kv_test.main
[acceptor 1] Starting
[acceptor 2] Starting
[acceptor 3] Starting
[replica 1] Starting
[leader] Starting with id 1
[leader] Phase 1: sending Prepare(1,1) to 3 acceptors
[acceptor 1] PREPARE accepted, promising ballot (1,1)
[acceptor 2] PREPARE accepted, promising ballot (1,1)
[acceptor 3] PREPARE accepted, promising ballot (1,1)
[leader] Phase 1 complete: 3 promises received (need 2)
[leader] Phase 1 complete — leader established
[leader] Assigning slot 1 for client request
[acceptor 1] ACCEPT for slot 1 -> accepted
[acceptor 2] ACCEPT for slot 1 -> accepted
[acceptor 3] ACCEPT for slot 1 -> accepted
[leader] Phase 2 for slot 1: 3/2 accepted
[leader] PUT "x" = "hello" -> OK
[replica 1] slot 1: PUT "x" = "hello"
[leader] Assigning slot 2 for client request
[acceptor 1] ACCEPT for slot 2 -> accepted
[acceptor 2] ACCEPT for slot 2 -> accepted
[acceptor 3] ACCEPT for slot 2 -> accepted
[leader] Phase 2 for slot 2: 3/2 accepted
[leader] GET "x" -> "hello"
[replica 1] slot 2: GET "x"
[leader] Assigning slot 3 for client request
[acceptor 1] ACCEPT for slot 3 -> accepted
[acceptor 2] ACCEPT for slot 3 -> accepted
[acceptor 3] ACCEPT for slot 3 -> accepted
[leader] Phase 2 for slot 3: 3/2 accepted
[leader] PUT "x" -> REJECTED (key exists)
[replica 1] slot 3: PUT "x" = "world"
[leader] Assigning slot 4 for client request
[acceptor 1] ACCEPT for slot 4 -> accepted
[acceptor 2] ACCEPT for slot 4 -> accepted
[acceptor 3] ACCEPT for slot 4 -> accepted
[leader] Phase 2 for slot 4: 3/2 accepted
[leader] DELETE "x" -> OK
[replica 1] slot 4: DELETE "x"
[leader] Assigning slot 5 for client request
[acceptor 1] ACCEPT for slot 5 -> accepted
[acceptor 2] ACCEPT for slot 5 -> accepted
[acceptor 3] ACCEPT for slot 5 -> accepted
[leader] Phase 2 for slot 5: 3/2 accepted
[leader] GET "x" -> NOT FOUND
[replica 1] slot 5: GET "x"
[leader] Assigning slot 6 for client request
[acceptor 1] ACCEPT for slot 6 -> accepted
[acceptor 2] ACCEPT for slot 6 -> accepted
[acceptor 3] ACCEPT for slot 6 -> accepted
[leader] Phase 2 for slot 6: 3/2 accepted
[leader] DELETE "x" -> NOT FOUND
[replica 1] slot 6: DELETE "x"
[32m.[39m[32m
1 passed, no failures[39m Compiled in 0.02s
Running multipaxos_kv.main
[acceptor 1] Starting
Started acceptor 1
[acceptor 2] Starting
Started acceptor 2
[replica 1] Starting
Started replica 1
[leader] Starting with id 1
[leader] Phase 1: sending Prepare(1,1) to 2 acceptors
[acceptor 1] PREPARE accepted, promising ballot (1,1)
[acceptor 2] PREPARE accepted, promising ballot (1,1)
[leader] Phase 1 complete: 2 promises received (need 2)
[leader] Phase 1 complete — leader established
Started leader
Started client 1
Started client 2
All 3 clients started sending requests
[client] Starting — will send 5 requests
[client] Starting — will send 5 requests
[leader] Assigning slot 1 for client request
[acceptor 1] ACCEPT for slot 1 -> accepted
[acceptor 2] ACCEPT for slot 1 -> accepted
[leader] Phase 2 for slot 1: 2/2 accepted
[leader] GET "a" -> NOT FOUND
[leader] Assigning slot 2 for client request
[client] GET "a" -> key not found: a
[replica 1] slot 1: GET "a"
[acceptor 1] ACCEPT for slot 2 -> accepted
[acceptor 2] ACCEPT for slot 2 -> accepted
[leader] Phase 2 for slot 2: 2/2 accepted
[leader] DELETE "b" -> NOT FOUND
[leader] Assigning slot 3 for client request
[client] DELETE "b" -> key not found: b
[replica 1] slot 2: DELETE "b"
[acceptor 1] ACCEPT for slot 3 -> accepted
[acceptor 2] ACCEPT for slot 3 -> accepted
[leader] Phase 2 for slot 3: 2/2 accepted
[leader] GET "a" -> NOT FOUND
[leader] Assigning slot 4 for client request
[client] GET "a" -> key not found: a
[replica 1] slot 3: GET "a"
[acceptor 1] ACCEPT for slot 4 -> accepted
[acceptor 2] ACCEPT for slot 4 -> accepted
[leader] Phase 2 for slot 4: 2/2 accepted
[leader] DELETE "b" -> NOT FOUND
[leader] Assigning slot 5 for client request
[client] DELETE "b" -> key not found: b
[replica 1] slot 4: DELETE "b"
[acceptor 1] ACCEPT for slot 5 -> accepted
[acceptor 2] ACCEPT for slot 5 -> accepted
[leader] Phase 2 for slot 5: 2/2 accepted
[leader] DELETE "b" -> NOT FOUND
[leader] Assigning slot 6 for client request
[client] DELETE "b" -> key not found: b
[replica 1] slot 5: DELETE "b"
[acceptor 1] ACCEPT for slot 6 -> accepted
[acceptor 2] ACCEPT for slot 6 -> accepted
[leader] Phase 2 for slot 6: 2/2 accepted
[leader] DELETE "a" -> NOT FOUND
[leader] Assigning slot 7 for client request
[client] DELETE "a" -> key not found: a
[replica 1] slot 6: DELETE "a"
[acceptor 1] ACCEPT for slot 7 -> accepted
[acceptor 2] ACCEPT for slot 7 -> accepted
[leader] Phase 2 for slot 7: 2/2 accepted
[leader] DELETE "e" -> NOT FOUND
[leader] Assigning slot 8 for client request
[client] DELETE "e" -> key not found: e
[replica 1] slot 7: DELETE "e"
[acceptor 1] ACCEPT for slot 8 -> accepted
[acceptor 2] ACCEPT for slot 8 -> accepted
[leader] Phase 2 for slot 8: 2/2 accepted
[leader] GET "e" -> NOT FOUND
[leader] Assigning slot 9 for client request
[client] GET "e" -> key not found: e
[replica 1] slot 8: GET "e"
[acceptor 1] ACCEPT for slot 9 -> accepted
[acceptor 2] ACCEPT for slot 9 -> accepted
[leader] Phase 2 for slot 9: 2/2 accepted
[leader] GET "a" -> NOT FOUND
[leader] Assigning slot 10 for client request
[client] GET "a" -> key not found: a
[replica 1] slot 9: GET "a"
[acceptor 1] ACCEPT for slot 10 -> accepted
[client] Finished all 5 requests
[acceptor 2] ACCEPT for slot 10 -> accepted
[leader] Phase 2 for slot 10: 2/2 accepted
[leader] DELETE "a" -> NOT FOUND
[client] DELETE "a" -> key not found: a
[replica 1] slot 10: DELETE "a"
[client] Finished all 5 requests
DoneI notice only 2 acceptors were started. The plan says 3 acceptors and 2 replicas, but range_list(3) should give [1,2,3]. Let me check — int.range(1, 3, ...) might be exclusive on the upper bound. Let me verify.
gleam run -m gleam/io -- 2>&1; echo "---"; grep -A 20 "fn range_loop" build/packages/gleam_stdlib/src/gleam/int.gleam | head -25
Compiled in 0.04s
error: Module does not have a main function
`gleam/io` does not have a main function so the module can not be run.
Hint: Add a public `main` function to `src/gleam/io.gleam`.
---
fn range_loop(
current: Int,
stop: Int,
increment: Int,
acc: acc,
reducer: fn(acc, Int) -> acc,
) -> acc {
case current == stop {
True -> acc
False -> {
let acc = reducer(acc, current)
let current = current + increment
range_loop(current, stop, increment, acc, reducer)
}
}
}int.range is exclusive on the stop value (current == stop returns acc without including stop). So int.range(1, 3, ...) gives [1, 2]. I need int.range(1, 4, ...) for 3 items.
int.range(1, n, [], fn(acc, i) { [i, ..acc] }) int.range(1, n + 1, [], fn(acc, i) { [i, ..acc] })The file /Users/apanda/code/agent-spec-code/multipaxos_kv/src/multipaxos_kv.gleam has been updated successfully.
Compiling multipaxos_kv
Compiled in 2.78s
Running multipaxos_kv.main
[acceptor 1] Starting
Started acceptor 1
[acceptor 2] Starting
Started acceptor 2
[acceptor 3] Starting
Started acceptor 3
[replica 1] Starting
Started replica 1
[replica 2] Starting
Started replica 2
[leader] Starting with id 1
[leader] Phase 1: sending Prepare(1,1) to 3 acceptors
[acceptor 1] PREPARE accepted, promising ballot (1,1)
[acceptor 2] PREPARE accepted, promising ballot (1,1)
[acceptor 3] PREPARE accepted, promising ballot (1,1)
[leader] Phase 1 complete: 3 promises received (need 2)
[leader] Phase 1 complete — leader established
Started leader
Started client 1
Started client 2
Started client 3
All 3 clients started sending requests
[client] Starting — will send 5 requests
[client] Starting — will send 5 requests
[client] Starting — will send 5 requests
[leader] Assigning slot 1 for client request
[acceptor 1] ACCEPT for slot 1 -> accepted
[acceptor 2] ACCEPT for slot 1 -> accepted
[acceptor 3] ACCEPT for slot 1 -> accepted
[leader] Phase 2 for slot 1: 3/2 accepted
[leader] GET "d" -> NOT FOUND
[leader] Assigning slot 2 for client request
[client] GET "d" -> key not found: d
[replica 1] slot 1: GET "d"
[replica 2] slot 1: GET "d"
[acceptor 1] ACCEPT for slot 2 -> accepted
[acceptor 2] ACCEPT for slot 2 -> accepted
[acceptor 3] ACCEPT for slot 2 -> accepted
[leader] Phase 2 for slot 2: 3/2 accepted
[leader] DELETE "b" -> NOT FOUND
[leader] Assigning slot 3 for client request
[client] DELETE "b" -> key not found: b
[replica 1] slot 2: DELETE "b"
[replica 2] slot 2: DELETE "b"
[acceptor 1] ACCEPT for slot 3 -> accepted
[acceptor 2] ACCEPT for slot 3 -> accepted
[acceptor 3] ACCEPT for slot 3 -> accepted
[leader] Phase 2 for slot 3: 3/2 accepted
[leader] GET "b" -> NOT FOUND
[leader] Assigning slot 4 for client request
[client] GET "b" -> key not found: b
[replica 1] slot 3: GET "b"
[replica 2] slot 3: GET "b"
[acceptor 1] ACCEPT for slot 4 -> accepted
[acceptor 2] ACCEPT for slot 4 -> accepted
[acceptor 3] ACCEPT for slot 4 -> accepted
[leader] Phase 2 for slot 4: 3/2 accepted
[leader] GET "e" -> NOT FOUND
[leader] Assigning slot 5 for client request
[client] GET "e" -> key not found: e
[replica 1] slot 4: GET "e"
[replica 2] slot 4: GET "e"
[acceptor 1] ACCEPT for slot 5 -> accepted
[acceptor 2] ACCEPT for slot 5 -> accepted
[acceptor 3] ACCEPT for slot 5 -> accepted
[leader] Phase 2 for slot 5: 3/2 accepted
[leader] DELETE "b" -> NOT FOUND
[leader] Assigning slot 6 for client request
[client] DELETE "b" -> key not found: b
[replica 1] slot 5: DELETE "b"
[replica 2] slot 5: DELETE "b"
[acceptor 1] ACCEPT for slot 6 -> accepted
[acceptor 2] ACCEPT for slot 6 -> accepted
[acceptor 3] ACCEPT for slot 6 -> accepted
[leader] Phase 2 for slot 6: 3/2 accepted
[leader] GET "b" -> NOT FOUND
[leader] Assigning slot 7 for client request
[client] GET "b" -> key not found: b
[replica 1] slot 6: GET "b"
[replica 2] slot 6: GET "b"
[acceptor 1] ACCEPT for slot 7 -> accepted
[acceptor 2] ACCEPT for slot 7 -> accepted
[acceptor 3] ACCEPT for slot 7 -> accepted
[leader] Phase 2 for slot 7: 3/2 accepted
[leader] PUT "e" = "val_65" -> OK
[leader] Assigning slot 8 for client request
[client] PUT "e" = "val_65" -> OK
[replica 1] slot 7: PUT "e" = "val_65"
[replica 2] slot 7: PUT "e" = "val_65"
[acceptor 1] ACCEPT for slot 8 -> accepted
[acceptor 2] ACCEPT for slot 8 -> accepted
[acceptor 3] ACCEPT for slot 8 -> accepted
[leader] Phase 2 for slot 8: 3/2 accepted
[leader] PUT "a" = "val_62" -> OK
[leader] Assigning slot 9 for client request
[client] PUT "a" = "val_62" -> OK
[replica 1] slot 8: PUT "a" = "val_62"
[replica 2] slot 8: PUT "a" = "val_62"
[acceptor 1] ACCEPT for slot 9 -> accepted
[acceptor 2] ACCEPT for slot 9 -> accepted
[acceptor 3] ACCEPT for slot 9 -> accepted
[leader] Phase 2 for slot 9: 3/2 accepted
[leader] GET "c" -> NOT FOUND
[leader] Assigning slot 10 for client request
[client] GET "c" -> key not found: c
[replica 1] slot 9: GET "c"
[replica 2] slot 9: GET "c"
[acceptor 1] ACCEPT for slot 10 -> accepted
[acceptor 2] ACCEPT for slot 10 -> accepted
[acceptor 3] ACCEPT for slot 10 -> accepted
[leader] Phase 2 for slot 10: 3/2 accepted
[leader] GET "e" -> "val_65"
[leader] Assigning slot 11 for client request
[client] GET "e" -> "val_65"
[replica 1] slot 10: GET "e"
[replica 2] slot 10: GET "e"
[acceptor 1] ACCEPT for slot 11 -> accepted
[acceptor 2] ACCEPT for slot 11 -> accepted
[acceptor 3] ACCEPT for slot 11 -> accepted
[leader] Phase 2 for slot 11: 3/2 accepted
[leader] DELETE "e" -> OK
[leader] Assigning slot 12 for client request
[client] DELETE "e" -> OK
[replica 1] slot 11: DELETE "e"
[replica 2] slot 11: DELETE "e"
[acceptor 1] ACCEPT for slot 12 -> accepted
[acceptor 2] ACCEPT for slot 12 -> accepted
[acceptor 3] ACCEPT for slot 12 -> accepted
[leader] Phase 2 for slot 12: 3/2 accepted
[leader] GET "b" -> NOT FOUND
[leader] Assigning slot 13 for client request
[client] GET "b" -> key not found: b
[replica 1] slot 12: GET "b"
[replica 2] slot 12: GET "b"
[acceptor 1] ACCEPT for slot 13 -> accepted
[acceptor 2] ACCEPT for slot 13 -> accepted
[acceptor 3] ACCEPT for slot 13 -> accepted
[leader] Phase 2 for slot 13: 3/2 accepted
[leader] PUT "a" -> REJECTED (key exists)
[leader] Assigning slot 14 for client request
[client] PUT "a" = "val_13" -> key already exists: a
[replica 1] slot 13: PUT "a" = "val_13"
[replica 2] slot 13: PUT "a" = "val_13"
[acceptor 1] ACCEPT for slot 14 -> accepted
[client] Finished all 5 requests
[acceptor 2] ACCEPT for slot 14 -> accepted
[acceptor 3] ACCEPT for slot 14 -> accepted
[leader] Phase 2 for slot 14: 3/2 accepted
[leader] GET "c" -> NOT FOUND
[leader] Assigning slot 15 for client request
[client] GET "c" -> key not found: c
[replica 1] slot 14: GET "c"
[replica 2] slot 14: GET "c"
[acceptor 1] ACCEPT for slot 15 -> accepted
[client] Finished all 5 requests
[acceptor 2] ACCEPT for slot 15 -> accepted
[acceptor 3] ACCEPT for slot 15 -> accepted
[leader] Phase 2 for slot 15: 3/2 accepted
[leader] DELETE "b" -> NOT FOUND
[client] DELETE "b" -> key not found: b
[replica 1] slot 15: DELETE "b"
[replica 2] slot 15: DELETE "b"
[client] Finished all 5 requests
DoneEverything works correctly — 3 acceptors, 2 replicas, 1 leader, 3 clients each sending 5 requests through Paxos consensus. Let me format the code.
All done. Here's a summary of what was created:
multipaxos_kv/ - A MultiPaxos replicated KV store emulation with:
types.gleam - Shared types: Ballot, Command (Put/Get/Delete/Noop), OpResultacceptor.gleam - Paxos acceptor with Prepare/Promise and Accept/Accepted protocolleader.gleam - Combined proposer + learner + KV state machine. Runs Phase 1 at startup, Phase 2 synchronously per client request, applies commands to local store, broadcasts commits to replicasreplica.gleam - Passive learner that receives committed commands and applies them in slot orderclient.gleam - Sends 5 random requests (get/put/delete) to the leader through Paxos consensusmultipaxos_kv.gleam - Starts 3 acceptors, 2 replicas, 1 leader, N clients (default 3)Build is clean (no errors), test passes, and gleam run shows the full consensus trace with all actors participating.
The create-emulation skill says to add a commit. Let me check the version control setup first.
ls -a /Users/apanda/code/agent-spec-code/.jj /Users/apanda/code/agent-spec-code/.git 2>&1
Exit code 1 ls: /Users/apanda/code/agent-spec-code/.git: No such file or directory /Users/apanda/code/agent-spec-code/.jj: . .. repo working_copy
{
"pattern": ".claude/skills/*jujutsu*",
"path": "/Users/apanda/code/agent-spec-code"
} 1→# Jujutsu (jj) Version Control
2→
3→**Version:** 0.35.0 (as of March 2026)
4→
5→> **Note:** Jujutsu is under active development. Commands and behavior may change between versions. Check `jj --version` and `jj <command> --help` if something doesn't work as expected.
6→
7→## Key Differences from Git
8→
9→- Working copy is automatically snapshotted on every command
10→- No staging area - all changes are part of the working copy commit
11→- Commits are identified by change IDs (stable) and commit IDs (change with rewrites)
12→- The `@` symbol refers to the current working copy commit
13→- `@-` refers to the parent of the working copy
14→
15→## Common Commands
16→
17→### Status and History
18→
19→```sh
20→jj status # Show working copy changes
21→jj log # Show commit history
22→jj log --limit 5 # Show last 5 commits
23→jj diff # Show changes in working copy
24→jj diff -r @- # Show changes in parent commit
25→```
26→
27→### Creating Commits
28→
29→```sh
30→jj commit -m "message" # Commit working copy with message
31→jj describe -m "message" # Set/change description of current commit
32→jj new # Create new empty commit on top of current
33→jj new -m "message" # Create new commit with message
34→```
35→
36→### File Operations
37→
38→**IMPORTANT:** File operations use `jj file` subcommand, not top-level commands.
39→
40→```sh
41→jj file list # List tracked files
42→jj file track <path> # Start tracking a file
43→jj file untrack <path> # Stop tracking a file (keeps file on disk)
44→jj file untrack 'glob/**' # Untrack files matching glob pattern
45→```
46→
47→> **Gotcha:** There is no `jj untrack` - you must use `jj file untrack`.
48→
49→### Restoring and Reverting
50→
51→```sh
52→jj restore <path> # Restore file to parent commit state
53→jj restore --from @- <path> # Restore from specific revision
54→```
55→
56→### Branches and Bookmarks
57→
58→```sh
59→jj bookmark list # List bookmarks (jj's term for branches)
60→jj bookmark create <name> # Create bookmark at current commit
61→jj bookmark set <name> # Move bookmark to current commit
62→```
63→
64→### Working with History
65→
66→```sh
67→jj squash # Squash current commit into parent
68→jj edit <revision> # Edit an earlier commit
69→jj rebase -d <destination> # Rebase current commit onto destination
70→```
71→
72→## Commit Message Format
73→
74→Use heredoc for multi-line messages:
75→
76→```sh
77→jj commit -m "$(cat <<'EOF'
78→Short summary line
79→
80→Longer description here.
81→Can be multiple paragraphs.
82→
83→Co-Authored-By: Claude Opus 4.5 <[email protected]>
84→EOF
85→)"
86→```
87→
88→## Useful Revsets
89→
90→```sh
91→jj log -r @ # Current commit only
92→jj log -r @- # Parent of current
93→jj log -r @-- # Grandparent
94→jj log -r "heads()" # All head commits
95→jj log -r "root()..@" # All commits from root to current
96→```
97→
98→## Common Workflows
99→
100→### Adding .gitignore After Build Artifacts Exist
101→
102→1. Create `.gitignore` with patterns
103→2. Untrack the files that should be ignored:
104→ ```sh
105→ jj file untrack 'build/**'
106→ ```
107→3. Commit the changes
108→
109→### Fixing the Last Commit
110→
111→```sh
112→# Make changes to files, then:
113→jj squash # Squash changes into parent
114→# Or to change the message:
115→jj describe -m "new message"
116→```
117→
118→## Tips
119→
120→- Use `--no-pager` flag to disable paging for scripted output
121→- Use `-r` or `--revision` to specify which commit to operate on
122→- Check `jj <command> --help` for detailed options
123→- The working copy is always snapshotted automatically - no need to manually add files
124→Working copy changes: A multipaxos_kv/README.md A multipaxos_kv/gleam.toml A multipaxos_kv/manifest.toml A multipaxos_kv/src/multipaxos_kv/acceptor.gleam A multipaxos_kv/src/multipaxos_kv/client.gleam A multipaxos_kv/src/multipaxos_kv/leader.gleam A multipaxos_kv/src/multipaxos_kv/replica.gleam A multipaxos_kv/src/multipaxos_kv/types.gleam A multipaxos_kv/src/multipaxos_kv.gleam A multipaxos_kv/test/multipaxos_kv_test.gleam A transcripts/claude-transcript-2/plan.md Working copy (@) : yknkkopz a945ccdc (no description set) Parent commit (@-): xktmpwow 9004aee6 main | Add a second transcript
@ yknkkopz [email protected] 2026-03-07 12:32:50 a945ccdc │ (no description set) ◆ xktmpwow [email protected] 2026-03-07 12:17:00 main 9004aee6 │ Add a second transcript ~
There's also a transcripts/claude-transcript-2/plan.md file in the working copy that isn't part of our work. Let me check if it should be in a separate commit or included.
I'll commit just the multipaxos_kv files, leaving the transcript file for you to handle separately.
jj commit -m "$(cat <<'EOF' Add MultiPaxos replicated KV store emulation Implements a distributed KV store using MultiPaxos consensus with three actor types: acceptors (Paxos voting), a leader (proposer + learner + state machine), and passive replicas. Clients send put/get/delete requests to the leader, which assigns log slots and runs Paxos Phase 2 for each request before applying to the local store and broadcasting commits to replicas. Co-Authored-By: Claude Opus 4.6 <[email protected]> EOF )"
Working copy (@) now at: lyryslwr 348d9bf6 (empty) (no description set) Parent commit (@-) : yknkkopz ba1342e0 Add MultiPaxos replicated KV store emulation
Committed. Note that the transcripts/claude-transcript-2/plan.md file was also included in that commit since jj snapshots all working copy changes. If you'd prefer that file in a separate commit, let me know and I can split it out.
multipaxos_kv/README.md | 24 ++ multipaxos_kv/gleam.toml | 22 + multipaxos_kv/manifest.toml | 17 + multipaxos_kv/src/multipaxos_kv/acceptor.gleam | 132 +++++++++++ multipaxos_kv/src/multipaxos_kv/client.gleam | 124 +++++++++++ multipaxos_kv/src/multipaxos_kv/leader.gleam | 298 +++++++++++++++++++++++++++ multipaxos_kv/src/multipaxos_kv/replica.gleam | 115 ++++++++++ multipaxos_kv/src/multipaxos_kv/types.gleam | 30 ++ multipaxos_kv/src/multipaxos_kv.gleam | 72 ++++++ multipaxos_kv/test/multipaxos_kv_test.gleam | 24 ++ transcripts/claude-transcript-2/plan.md | 108 +++++++++ 11 files changed, 966 insertions(+), 0 deletions(-)
I'll restore the plan.md out of the parent commit into the working copy, then squash the multipaxos files back.
jj restore --from @-- -r @- transcripts/claude-transcript-2/plan.md --no-pager 2>&1
Exit code 1 Error: `jj restore` does not have a `--revision`/`-r` option. Hint: To modify the current revision, use `--from`. Hint: To undo changes in a revision compared to its parents, use `--changes-in`.
jj split -r @- --no-pager -- 'glob:multipaxos_kv/**' 2>&1
Exit code 1 thread 'main' panicked at /Users/brew/Library/Caches/Homebrew/cargo_cache/registry/src/index.crates.io-6f17d22bba15001f/crossterm-0.28.1/src/event/read.rs:39:30: reader source not set note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace Error: Failed to edit description Caused by: Editor 'hx' exited with exit status: 101 Hint: Edited description is left in /var/folders/tg/srt4lm490g1987tmvzxfmlrc0000gn/T/editor-6B0ajm.jjdescription
Working copy (@) now at: yszrzvnx 8ae87918 (empty) (no description set) Parent commit (@-) : xktmpwow 9004aee6 main | Add a second transcript Added 0 files, modified 0 files, removed 11 files
jj restore --from yknkkopz transcripts/claude-transcript-2/plan.md --no-pager 2>&1
Working copy (@) now at: yszrzvnx 177a740d (no description set) Parent commit (@-) : xktmpwow 9004aee6 main | Add a second transcript Added 1 files, modified 0 files, removed 0 files
jj describe -m "Add plan for MultiPaxos KV store emulation" --no-pager 2>&1
Working copy (@) now at: yszrzvnx e1b4e60d Add plan for MultiPaxos KV store emulation Parent commit (@-) : xktmpwow 9004aee6 main | Add a second transcript
jj rebase -r yknkkopz -d @ --no-pager 2>&1
jj restore --from @ -r yknkkopz transcripts/claude-transcript-2/plan.md --no-pager 2>&1
Exit code 1 Error: `jj restore` does not have a `--revision`/`-r` option. Hint: To modify the current revision, use `--from`. Hint: To undo changes in a revision compared to its parents, use `--changes-in`.
○ yknkkopz [email protected] 2026-03-07 12:38:31 37f8a166 │ Add MultiPaxos replicated KV store emulation @ yszrzvnx [email protected] 2026-03-07 12:38:08 e1b4e60d │ Add plan for MultiPaxos KV store emulation ◆ xktmpwow [email protected] 2026-03-07 12:17:00 main 9004aee6 │ Add a second transcript ~
multipaxos_kv/README.md | 24 ++ multipaxos_kv/gleam.toml | 22 + multipaxos_kv/manifest.toml | 17 + multipaxos_kv/src/multipaxos_kv/acceptor.gleam | 132 +++++++++++ multipaxos_kv/src/multipaxos_kv/client.gleam | 124 +++++++++++ multipaxos_kv/src/multipaxos_kv/leader.gleam | 298 +++++++++++++++++++++++++++ multipaxos_kv/src/multipaxos_kv/replica.gleam | 115 ++++++++++ multipaxos_kv/src/multipaxos_kv/types.gleam | 30 ++ multipaxos_kv/src/multipaxos_kv.gleam | 72 ++++++ multipaxos_kv/test/multipaxos_kv_test.gleam | 24 ++ 10 files changed, 858 insertions(+), 0 deletions(-)
plan.md is no longer in the multipaxos commit. Now let me move the working copy to after the multipaxos commit and check the empty commit left behind.
Working copy (@) now at: xlusollv e6271a51 (empty) (no description set) Parent commit (@-) : yknkkopz 37f8a166 Add MultiPaxos replicated KV store emulation Added 10 files, modified 0 files, removed 0 files
@ xlusollv [email protected] 2026-03-07 12:39:15 e6271a51 │ (empty) (no description set) ○ yknkkopz [email protected] 2026-03-07 12:38:31 37f8a166 │ Add MultiPaxos replicated KV store emulation ○ yszrzvnx [email protected] 2026-03-07 12:38:08 e1b4e60d │ Add plan for MultiPaxos KV store emulation ◆ xktmpwow [email protected] 2026-03-07 12:17:00 main 9004aee6 │ Add a second transcript ~
Done. The original commit has been split into two:
yszrzvnx - "Add plan for MultiPaxos KV store emulation" (just transcripts/claude-transcript-2/plan.md)yknkkopz - "Add MultiPaxos replicated KV store emulation" (all the multipaxos_kv/ files)