Phase 2: Clean package boundaries — declarative make-pipeline DSL

- New make-pipeline function: single declarative call creates server,
  mounts, encoders, and pipeline wiring from an output spec
- Pipeline owns encoder lifecycle (pipeline-encoders slot, auto-cleanup)
- Pipeline owns server when it creates one (pipeline-owns-server-p)
- Hook system wired: pipeline-add-hook fires on track-change and
  playlist-change via pipeline-fire-hook
- stream-harmony.lisp slimmed: start is 1 make-pipeline + 2 hooks,
  stop is 1 pipeline-stop call (cleanup automatic)
- Removed global encoder variables from Asteroid glue layer
- Backward-compatible: dj-session.lisp unchanged, cl-streamer:*server*
  still set for legacy callers

Runtime verified: audio streams, metadata displays, crossfades work.

cl-streamer/harmony-backend.lisp

@@ -21,6 +21,8 @@
                 #:pipeline-fire-hook)
   (:export #:audio-pipeline
            #:make-audio-pipeline
+           #:make-pipeline
+           #:make-encoder-for-format
            #:add-pipeline-output
            ;; Re-export protocol generics so callers can use cl-streamer/harmony:X
            #:pipeline-start
@@ -38,6 +40,9 @@
            #:pipeline-add-hook
            #:pipeline-remove-hook
            #:pipeline-fire-hook
+           ;; Pipeline state accessors
+           #:pipeline-encoders
+           #:pipeline-owns-server-p
            ;; Backward-compatible aliases (delegate to protocol generics)
            #:start-pipeline
            #:stop-pipeline
@@ -160,7 +165,12 @@
                        :documentation "Callback (lambda (pipeline playlist-path)) called when scheduler playlist starts")
    ;; Hook system
    (hooks :initform (make-hash-table :test 'eq) :reader pipeline-hooks
-          :documentation "Hash table mapping event keywords to lists of hook functions")))
+          :documentation "Hash table mapping event keywords to lists of hook functions")
+   ;; Encoder & server ownership (Phase 2)
+   (encoders :initform nil :accessor pipeline-encoders
+             :documentation "List of (encoder . mount-path) pairs owned by the pipeline")
+   (owns-server :initform nil :accessor pipeline-owns-server-p
+                :documentation "T if pipeline created the server and should stop it on shutdown")))
 
 (defun make-audio-pipeline (&key encoder stream-server (mount-path "/stream.mp3")
                                  (sample-rate 44100) (channels 2))
@@ -178,6 +188,81 @@
       (drain-add-output (pipeline-drain pipeline) encoder mount-path))
     pipeline))
 
+(defun make-encoder-for-format (format &key (bitrate 128) (sample-rate 44100) (channels 2))
+  "Create an encoder for the given FORMAT keyword (:mp3 or :aac)."
+  (ecase format
+    (:mp3 (cl-streamer:make-mp3-encoder :bitrate bitrate
+                                         :sample-rate sample-rate
+                                         :channels channels))
+    (:aac (cl-streamer:make-aac-encoder :bitrate (* bitrate 1000)
+                                         :sample-rate sample-rate
+                                         :channels channels))))
+
+(defun content-type-for-format (format)
+  "Return the MIME content type for FORMAT keyword."
+  (ecase format
+    (:mp3 "audio/mpeg")
+    (:aac "audio/aac")))
+
+(defun make-pipeline (&key (port 8000) (sample-rate 44100) (channels 2) outputs server)
+  "Create a complete streaming pipeline from a declarative spec.
+   PORT: stream server port (ignored if SERVER is provided).
+   OUTPUTS: list of output specs, each a plist:
+     (:format :mp3 :mount \"/stream.mp3\" :bitrate 128 :name \"My Stream\")
+   SERVER: an existing stream-server instance (optional).
+     If NIL, a new server is created and owned by the pipeline.
+
+   Example:
+     (make-pipeline :port 8000
+                    :outputs '((:format :mp3 :mount \"/radio.mp3\" :bitrate 128
+                                :name \"Radio MP3\")
+                               (:format :aac :mount \"/radio.aac\" :bitrate 128
+                                :name \"Radio AAC\")))
+
+   Returns the pipeline (already wired, but not started — call pipeline-start)."
+  (let* ((owns-server (null server))
+         (srv (or server
+                  (let ((s (cl-streamer:make-stream-server :port port)))
+                    (cl-streamer:start-server s)
+                    ;; Set global so write-audio-data/set-now-playing work
+                    (setf cl-streamer:*server* s)
+                    s)))
+         (pipeline (make-instance 'audio-pipeline
+                                  :stream-server srv
+                                  :sample-rate sample-rate
+                                  :channels channels))
+         (encoders nil))
+    (setf (pipeline-owns-server-p pipeline) owns-server)
+    ;; Create drain
+    (setf (pipeline-drain pipeline)
+          (make-instance 'streaming-drain :channels channels))
+    ;; Process each output spec
+    (dolist (spec outputs)
+      (let* ((format (getf spec :format))
+             (mount (getf spec :mount))
+             (bitrate (or (getf spec :bitrate) 128))
+             (name (or (getf spec :name) "CL-Streamer"))
+             (genre (or (getf spec :genre) "Various"))
+             (content-type (or (getf spec :content-type)
+                               (content-type-for-format format)))
+             (encoder (make-encoder-for-format format
+                                               :bitrate bitrate
+                                               :sample-rate sample-rate
+                                               :channels channels)))
+        ;; Add mount point to server
+        (cl-streamer:add-mount srv mount
+                               :content-type content-type
+                               :bitrate bitrate
+                               :name name
+                               :genre genre)
+        ;; Wire encoder to drain
+        (drain-add-output (pipeline-drain pipeline) encoder mount)
+        (push (cons encoder mount) encoders)))
+    (setf (pipeline-encoders pipeline) (nreverse encoders))
+    (log:info "Pipeline configured: ~A outputs on port ~A"
+              (length outputs) (if owns-server port (cl-streamer::server-port srv)))
+    pipeline))
+
 (defun add-pipeline-output (pipeline encoder mount-path)
   "Add an additional encoder/mount output to the pipeline.
    Can be called before or after start-pipeline."
@@ -224,11 +309,23 @@
   pipeline)
 
 (defmethod pipeline-stop ((pipeline audio-pipeline))
-  "Stop the audio pipeline."
+  "Stop the audio pipeline. Cleans up owned encoders and server."
   (setf (%pipeline-running pipeline) nil)
   (when (pipeline-harmony-server pipeline)
     (mixed:end (pipeline-harmony-server pipeline))
     (setf (pipeline-harmony-server pipeline) nil))
+  ;; Close owned encoders
+  (dolist (pair (pipeline-encoders pipeline))
+    (handler-case
+        (cl-streamer:encoder-close (car pair))
+      (error (e) (log:debug "Error closing encoder for ~A: ~A" (cdr pair) e))))
+  (setf (pipeline-encoders pipeline) nil)
+  ;; Stop owned server
+  (when (pipeline-owns-server-p pipeline)
+    (handler-case
+        (cl-streamer:stop-server (pipeline-server pipeline))
+      (error (e) (log:debug "Error stopping server: ~A" e)))
+    (setf (pipeline-owns-server-p pipeline) nil))
   (log:info "Audio pipeline stopped")
   pipeline)
 
@@ -337,8 +434,11 @@
   (update-all-mounts-metadata pipeline title))
 
 (defun notify-track-change (pipeline track-info)
-  "Update pipeline state and fire the on-track-change callback."
+  "Update pipeline state and fire hooks + legacy callback."
   (setf (%pipeline-current-track pipeline) track-info)
+  ;; Fire hook system (Phase 2)
+  (pipeline-fire-hook pipeline :track-change track-info)
+  ;; Legacy callback (backward compat)
   (when (pipeline-on-track-change pipeline)
     (handler-case
         (funcall (pipeline-on-track-change pipeline) pipeline track-info)
@@ -418,16 +518,19 @@
         ;; Replace remaining list and update current for loop-queue
         (setf (car remaining-ref) all-queued)
         (setf (car current-list-ref) (copy-list all-queued))
-        ;; Fire playlist-change callback so app layer updates metadata
+        ;; Fire hooks + legacy callback so app layer updates metadata
-        (when (pipeline-on-playlist-change pipeline)
         (let ((playlist-path (pipeline-pending-playlist-path pipeline)))
           (when playlist-path
+            ;; Fire hook system (Phase 2)
+            (pipeline-fire-hook pipeline :playlist-change playlist-path)
+            ;; Legacy callback (backward compat)
+            (when (pipeline-on-playlist-change pipeline)
               (handler-case
                   (funcall (pipeline-on-playlist-change pipeline)
                            pipeline playlist-path)
                 (error (e)
-                  (log:warn "Playlist change callback error: ~A" e)))
+                  (log:warn "Playlist change callback error: ~A" e))))
-              (setf (pipeline-pending-playlist-path pipeline) nil))))
+            (setf (pipeline-pending-playlist-path pipeline) nil)))
         t))))
 
 (defun next-entry (pipeline remaining-ref current-list-ref)

stream-harmony.lisp

@@ -12,11 +12,19 @@
 (defvar *harmony-stream-port* 8000
   "Port for the cl-streamer HTTP stream server.")
 
-(defvar *harmony-mp3-encoder* nil
+;; Encoder instances are now owned by the pipeline (Phase 2).
-  "MP3 encoder instance.")
+;; Kept as aliases for backward compatibility with any external references.
+(defun harmony-mp3-encoder ()
+  "Get the MP3 encoder from the pipeline (if running)."
+  (when *harmony-pipeline*
+    (car (find "/asteroid.mp3" (cl-streamer/harmony:pipeline-encoders *harmony-pipeline*)
+               :key #'cdr :test #'string=))))
 
-(defvar *harmony-aac-encoder* nil
+(defun harmony-aac-encoder ()
-  "AAC encoder instance.")
+  "Get the AAC encoder from the pipeline (if running)."
+  (when *harmony-pipeline*
+    (car (find "/asteroid.aac" (cl-streamer/harmony:pipeline-encoders *harmony-pipeline*)
+               :key #'cdr :test #'string=))))
 
 (defvar *harmony-state-file*
   (merge-pathnames ".playback-state.lisp" (asdf:system-source-directory :asteroid))
@@ -197,75 +205,46 @@
 ;;; ---- Pipeline Lifecycle ----
 
 (defun start-harmony-streaming (&key (port *harmony-stream-port*)
-                                     (mp3-bitrate 128000)
+                                     (mp3-bitrate 128)
-                                     (aac-bitrate 128000))
+                                     (aac-bitrate 128))
   "Start the cl-streamer pipeline with MP3 and AAC outputs.
-   Should be called once during application startup."
+   Should be called once during application startup.
+   MP3-BITRATE and AAC-BITRATE are in kbps (e.g. 128)."
   (when *harmony-pipeline*
     (log:warn "Harmony streaming already running")
     (return-from start-harmony-streaming *harmony-pipeline*))
 
-  ;; Start the stream server
+  ;; Create pipeline from declarative spec — server, mounts, encoders all handled
-  (cl-streamer:start :port port)
-
-  ;; Add mount points
-  (cl-streamer:add-mount cl-streamer:*server* "/asteroid.mp3"
-                         :content-type "audio/mpeg"
-                         :bitrate 128
-                         :name "Asteroid Radio MP3")
-  (cl-streamer:add-mount cl-streamer:*server* "/asteroid.aac"
-                         :content-type "audio/aac"
-                         :bitrate 128
-                         :name "Asteroid Radio AAC")
-
-  ;; Create encoders
-  (setf *harmony-mp3-encoder*
-        (cl-streamer:make-mp3-encoder :bitrate (floor mp3-bitrate 1000)
-                                      :sample-rate 44100
-                                      :channels 2))
-  (setf *harmony-aac-encoder*
-        (cl-streamer:make-aac-encoder :bitrate aac-bitrate
-                                      :sample-rate 44100
-                                      :channels 2))
-
-  ;; Create pipeline with track-change callback
   (setf *harmony-pipeline*
-        (cl-streamer/harmony:make-audio-pipeline
+        (cl-streamer/harmony:make-pipeline
-         :encoder *harmony-mp3-encoder*
+         :port port
-         :stream-server cl-streamer:*server*
+         :outputs (list (list :format :mp3
-         :mount-path "/asteroid.mp3"))
+                              :mount "/asteroid.mp3"
+                              :bitrate mp3-bitrate
+                              :name "Asteroid Radio MP3")
+                        (list :format :aac
+                              :mount "/asteroid.aac"
+                              :bitrate aac-bitrate
+                              :name "Asteroid Radio AAC"))))
 
-  ;; Add AAC output
+  ;; Register hooks
-  (cl-streamer/harmony:add-pipeline-output *harmony-pipeline*
+  (cl-streamer/harmony:pipeline-add-hook *harmony-pipeline*
-                                           *harmony-aac-encoder*
+                                         :track-change #'on-harmony-track-change)
-                                           "/asteroid.aac")
+  (cl-streamer/harmony:pipeline-add-hook *harmony-pipeline*
-
+                                         :playlist-change #'on-harmony-playlist-change)
-  ;; Set the track-change callback
-  (setf (cl-streamer/harmony:pipeline-on-track-change *harmony-pipeline*)
-        #'on-harmony-track-change)
-
-  ;; Set the playlist-change callback (fires when scheduler playlist actually starts)
-  (setf (cl-streamer/harmony:pipeline-on-playlist-change *harmony-pipeline*)
-        #'on-harmony-playlist-change)
 
   ;; Start the audio pipeline
-  (cl-streamer/harmony:start-pipeline *harmony-pipeline*)
+  (cl-streamer/harmony:pipeline-start *harmony-pipeline*)
 
   (log:info "Harmony streaming started on port ~A (MP3 + AAC)" port)
   *harmony-pipeline*)
 
 (defun stop-harmony-streaming ()
-  "Stop the cl-streamer pipeline and stream server."
+  "Stop the cl-streamer pipeline and stream server.
+   Pipeline owns encoders and server — cleanup is automatic."
   (when *harmony-pipeline*
-    (cl-streamer/harmony:stop-pipeline *harmony-pipeline*)
+    (cl-streamer/harmony:pipeline-stop *harmony-pipeline*)
     (setf *harmony-pipeline* nil))
-  (when *harmony-mp3-encoder*
-    (cl-streamer:close-encoder *harmony-mp3-encoder*)
-    (setf *harmony-mp3-encoder* nil))
-  (when *harmony-aac-encoder*
-    (cl-streamer:close-aac-encoder *harmony-aac-encoder*)
-    (setf *harmony-aac-encoder* nil))
-  (cl-streamer:stop)
   (log:info "Harmony streaming stopped"))
 
 ;;; ---- Playlist Control ----