hive-hot

Hot-reload module for Clojure - figwheel/shadow-cljs for backend.

Status

v0.1.0 - Core registry + reload!

Overview

hive-hot provides unified hot-reload for Clojure backend development, built on tonsky/clj-reload:

• Built on clj-reload - Leverages battle-tested reload mechanics
• Component registry - Named components with lifecycle callbacks
• Event-driven listeners - Integrates with hive-events
• MCP-accessible - Coordinator/lings can trigger reloads externally
• Observable - Channel notifications on reload status

Installation

;; deps.edn
{:deps {io.github.hive-agi/hive-hot {:git/tag "v0.1.0" :git/sha "..."}}}

Quick Start

(require '[hive-hot.core :as hot])

;; Register a component for hot-reload
(hot/reg-hot :my-service
  {:ns 'my.service.core
   :on-reload (fn [] (println "Service reloaded!"))
   :on-error (fn [e] (println "Reload failed:" e))})

;; Trigger reload (also reloads dependents)
(hot/reload!)

;; Refresh all namespaces
(hot/reload-all!)

Usage Examples

Event Listeners

Subscribe to reload events for logging, metrics, or integration:

;; Add a listener for reload events
(hot/add-listener! :my-logger
  (fn [event]
    (case (:type event)
      :reload-start   (println "Reload starting...")
      :reload-success (println "Reloaded" (count (:loaded event)) "namespaces in" (:ms event) "ms")
      :reload-error   (println "Reload failed:" (:failed event))
      :component-callback (println "Component" (:component event) "callback:" (:callback event))
      nil)))

;; Remove when done
(hot/remove-listener! :my-logger)

Component Lifecycle

Register components that need callbacks after reload:

;; HTTP server that needs restart notification
(hot/reg-hot :http-server
  {:ns 'my.server.core
   :on-reload (fn []
                (println "Server code changed!")
                ;; Could restart server here if needed
                )
   :on-error (fn [e]
               (println "Server reload failed:" (.getMessage e)))})

;; Database connection pool
(hot/reg-hot :db-pool
  {:ns 'my.db.pool
   :on-reload #(println "DB pool namespace reloaded")})

;; List registered components
(hot/list-components)
;; => (:http-server :db-pool)

;; Get component details
(hot/get-component :http-server)
;; => {:ns my.server.core, :on-reload #fn, :on-error #fn, :status :idle, :last-reload #inst...}

Status Introspection

Check the current state of the hot-reload system:

(hot/status)
;; => {:initialized? true
;;     :components {:http-server {...} :db-pool {...}}
;;     :listener-count 1}

Development Workflow

Use with-reload for interactive development:

;; Make a change and reload in one step
(hot/with-reload
  (spit "src/my/service.clj"
        (slurp "src/my/service.clj")))

;; Or just reload after external edits
(hot/reload!)

Initialization Options

Configure source directories and exclusions:

;; Custom initialization
(hot/init! {:dirs ["src" "dev"]
            :no-reload '#{user}           ; Never reload these
            :no-unload '#{my.stateful}})  ; Reload but don't unload

;; Find namespaces by pattern
(hot/find-namespaces #".*-test")
;; => (my.service-test my.db-test ...)

API Reference

Initialization

Function	Signature	Description
init!	([] [opts])	Initialize clj-reload. Options: :dirs, :no-reload, :no-unload

Component Registry

Function	Signature	Description
reg-hot	[id opts]	Register component. Opts: :ns (required), :on-reload, :on-error
unreg-hot	[id]	Unregister component
get-component	[id]	Get component map by ID
list-components	[]	List all registered component IDs

Reload Operations

Function	Signature	Description
reload!	([] [opts])	Reload changed namespaces. Opts: :throw, :only
reload-all!	[]	Force reload all namespaces

Event Listeners

Function	Signature	Description
add-listener!	[id fn]	Add reload event listener
remove-listener!	[id]	Remove listener by ID

Introspection

Function	Signature	Description
status	[]	Get system status map
reset!	[]	Clear all registrations (for tests)
find-namespaces	[pattern]	Find namespaces matching regex

Macros

Macro	Description
with-reload	Execute body, then call reload!

Architecture

File Change -> Event -> Dependency Graph -> Ordered Reload -> Notify
     |           |           |                |            |
  watcher   :hot/file   tools.namespace   require      channel
            -changed                      :reload      publish

Development

# Start REPL with dev dependencies
clj -M:dev:nrepl

# Run tests
clj -X:test

# REPL workflow
(require '[hive-hot.core :as hot])
(hot/init! {:dirs ["src" "test"]})
(hot/reload!)

Roadmap

• v0.1.0 - Core registry + reload! + reload-all!
• v0.2.0 - File watcher integration
• v0.3.0 - MCP tools (hot_reload, hot_status)
• v0.4.0 - hive-events effects integration

Part of hive-agi

• hive-mcp - Core MCP server
• hive-events - Event system
• hive-hot - Hot-reload module (this repo)

License

MIT