feat: implement queue pruning and message rotation

Enforce QUEUE_MAX_AGE and MAX_HISTORY config values that previously
existed but were not applied. The existing cleanup loop now also:

- Prunes client_queues entries older than QUEUE_MAX_AGE (default 48h)
- Rotates messages per target (channel/DM) beyond MAX_HISTORY (default 10000)
- Removes orphaned messages no longer referenced by any client queue

closes #40

README.md

@@ -1784,10 +1784,11 @@ skew issues) and simpler than UUIDs (integer comparison vs. string comparison).
 
 ### Data Lifecycle
 
-- **Messages**: Stored indefinitely in the current implementation. Rotation
-  per `MAX_HISTORY` is planned.
-- **Queue entries**: Stored until pruned. Pruning by `QUEUE_MAX_AGE` is
-  planned.
+- **Messages**: Rotated per `MAX_HISTORY` — oldest messages beyond the limit
+  are pruned periodically per target (channel or DM). Orphaned messages (no
+  longer referenced by any client queue) are also removed.
+- **Queue entries**: Pruned automatically when older than `QUEUE_MAX_AGE`
+  (default 48h).
 - **Channels**: Deleted when the last member leaves (ephemeral).
 - **Users/sessions**: Deleted on `QUIT` or `POST /api/v1/logout`. Idle
   sessions are automatically expired after `SESSION_IDLE_TIMEOUT` (default
@@ -1808,9 +1809,9 @@ directory is also loaded automatically via
 | `PORT`             | int     | `8080`                               | HTTP listen port |
 | `DBURL`            | string  | `file:///var/lib/neoirc/state.db?_journal_mode=WAL` | SQLite connection string. For file-based: `file:///path/to/db.db?_journal_mode=WAL`. For in-memory (testing): `file::memory:?cache=shared`. |
 | `DEBUG`            | bool    | `false`                              | Enable debug logging (verbose request/response logging) |
-| `MAX_HISTORY`      | int     | `10000`                              | Maximum messages retained per channel before rotation (planned) |
+| `MAX_HISTORY`      | int     | `10000`                              | Maximum messages retained per target (channel or DM) before rotation |
 | `SESSION_IDLE_TIMEOUT` | string | `24h`                            | Session idle timeout as a Go duration string (e.g. `24h`, `30m`). Sessions with no activity for this long are expired and the nick is released. |
-| `QUEUE_MAX_AGE`    | int     | `172800`                             | Maximum age of client queue entries in seconds (48h). Entries older than this are pruned (planned). |
+| `QUEUE_MAX_AGE`    | int     | `172800`                             | Maximum age of client queue entries in seconds (48h). Entries older than this are pruned. |
 | `MAX_MESSAGE_SIZE` | int     | `4096`                               | Maximum message body size in bytes (planned enforcement) |
 | `LONG_POLL_TIMEOUT`| int     | `15`                                 | Default long-poll timeout in seconds (client can override via query param, server caps at 30) |
 | `MOTD`             | string  | `""`                                 | Message of the day, shown to clients via `GET /api/v1/server` |
@@ -2224,8 +2225,8 @@ GET /api/v1/challenge
 ### Post-MVP (Planned)
 
 - [ ] **Hashcash proof-of-work** for session creation (abuse prevention)
-- [ ] **Queue pruning** — delete old queue entries per `QUEUE_MAX_AGE`
-- [ ] **Message rotation** — enforce `MAX_HISTORY` per channel
+- [x] **Queue pruning** — delete old queue entries per `QUEUE_MAX_AGE`
+- [x] **Message rotation** — enforce `MAX_HISTORY` per target
 - [ ] **Channel modes** — enforce `+i`, `+m`, `+s`, `+t`, `+n`
 - [ ] **User channel modes** — `+o` (operator), `+v` (voice)
 - [x] **MODE command** — query channel and user modes (set not yet implemented)

internal/config/config.go

@@ -40,6 +40,7 @@ type Config struct {
 	SentryDSN          string
 	MaxHistory         int
 	MaxMessageSize     int
+	QueueMaxAge        int
 	MOTD               string
 	ServerName         string
 	FederationKey      string
@@ -70,6 +71,7 @@ func New(
 	viper.SetDefault("METRICS_PASSWORD", "")
 	viper.SetDefault("MAX_HISTORY", "10000")
 	viper.SetDefault("MAX_MESSAGE_SIZE", "4096")
+	viper.SetDefault("QUEUE_MAX_AGE", "172800")
 	viper.SetDefault("MOTD", defaultMOTD)
 	viper.SetDefault("SERVER_NAME", "")
 	viper.SetDefault("FEDERATION_KEY", "")
@@ -94,6 +96,7 @@ func New(
 		MetricsPassword:    viper.GetString("METRICS_PASSWORD"),
 		MaxHistory:         viper.GetInt("MAX_HISTORY"),
 		MaxMessageSize:     viper.GetInt("MAX_MESSAGE_SIZE"),
+		QueueMaxAge:        viper.GetInt("QUEUE_MAX_AGE"),
 		MOTD:               viper.GetString("MOTD"),
 		ServerName:         viper.GetString("SERVER_NAME"),
 		FederationKey:      viper.GetString("FEDERATION_KEY"),

internal/db/queries.go

@@ -1096,3 +1096,128 @@ func (database *Database) GetSessionCreatedAt(
 
 	return createdAt, nil
 }
+
+// PruneOldQueueEntries deletes client_queues rows older
+// than cutoff and returns the number of rows removed.
+func (database *Database) PruneOldQueueEntries(
+	ctx context.Context,
+	cutoff time.Time,
+) (int64, error) {
+	res, err := database.conn.ExecContext(ctx,
+		"DELETE FROM client_queues WHERE created_at < ?",
+		cutoff,
+	)
+	if err != nil {
+		return 0, fmt.Errorf(
+			"prune old queue entries: %w", err,
+		)
+	}
+
+	deleted, _ := res.RowsAffected()
+
+	return deleted, nil
+}
+
+// PruneOrphanedMessages deletes messages that are no
+// longer referenced by any client_queues row and returns
+// the number of rows removed.
+func (database *Database) PruneOrphanedMessages(
+	ctx context.Context,
+) (int64, error) {
+	res, err := database.conn.ExecContext(ctx,
+		`DELETE FROM messages WHERE id NOT IN
+		 (SELECT DISTINCT message_id
+		  FROM client_queues)`,
+	)
+	if err != nil {
+		return 0, fmt.Errorf(
+			"prune orphaned messages: %w", err,
+		)
+	}
+
+	deleted, _ := res.RowsAffected()
+
+	return deleted, nil
+}
+
+// RotateChannelMessages enforces MAX_HISTORY per channel
+// by deleting the oldest messages beyond the limit for
+// each msg_to target. Returns the total number of rows
+// removed.
+func (database *Database) RotateChannelMessages(
+	ctx context.Context,
+	maxHistory int,
+) (int64, error) {
+	if maxHistory <= 0 {
+		return 0, nil
+	}
+
+	// Find distinct targets that have messages.
+	rows, err := database.conn.QueryContext(ctx,
+		`SELECT msg_to, COUNT(*) AS cnt
+		 FROM messages
+		 WHERE msg_to != ''
+		 GROUP BY msg_to
+		 HAVING cnt > ?`,
+		maxHistory,
+	)
+	if err != nil {
+		return 0, fmt.Errorf(
+			"list targets for rotation: %w", err,
+		)
+	}
+
+	defer func() { _ = rows.Close() }()
+
+	type targetCount struct {
+		target string
+		count  int64
+	}
+
+	var targets []targetCount
+
+	for rows.Next() {
+		var entry targetCount
+
+		err = rows.Scan(&entry.target, &entry.count)
+		if err != nil {
+			return 0, fmt.Errorf(
+				"scan target count: %w", err,
+			)
+		}
+
+		targets = append(targets, entry)
+	}
+
+	err = rows.Err()
+	if err != nil {
+		return 0, fmt.Errorf("rows error: %w", err)
+	}
+
+	var totalDeleted int64
+
+	for _, entry := range targets {
+		res, delErr := database.conn.ExecContext(ctx,
+			`DELETE FROM messages
+			 WHERE msg_to = ?
+			   AND id NOT IN (
+			     SELECT id FROM messages
+			     WHERE msg_to = ?
+			     ORDER BY id DESC
+			     LIMIT ?
+			   )`,
+			entry.target, entry.target, maxHistory,
+		)
+		if delErr != nil {
+			return totalDeleted, fmt.Errorf(
+				"rotate messages for %s: %w",
+				entry.target, delErr,
+			)
+		}
+
+		deleted, _ := res.RowsAffected()
+		totalDeleted += deleted
+	}
+
+	return totalDeleted, nil
+}

internal/handlers/handlers.go

@@ -200,4 +200,63 @@ func (hdlr *Handlers) runCleanup(
 			"deleted", deleted,
 		)
 	}
+
+	hdlr.pruneQueuesAndMessages(ctx)
+}
+
+// pruneQueuesAndMessages removes old client_queues entries
+// per QUEUE_MAX_AGE, rotates messages per MAX_HISTORY, and
+// cleans up orphaned messages.
+func (hdlr *Handlers) pruneQueuesAndMessages(
+	ctx context.Context,
+) {
+	queueMaxAge := hdlr.params.Config.QueueMaxAge
+	if queueMaxAge > 0 {
+		queueCutoff := time.Now().Add(
+			-time.Duration(queueMaxAge) * time.Second,
+		)
+
+		pruned, err := hdlr.params.Database.
+			PruneOldQueueEntries(ctx, queueCutoff)
+		if err != nil {
+			hdlr.log.Error(
+				"queue pruning failed", "error", err,
+			)
+		} else if pruned > 0 {
+			hdlr.log.Info(
+				"pruned old queue entries",
+				"deleted", pruned,
+			)
+		}
+	}
+
+	maxHistory := hdlr.params.Config.MaxHistory
+	if maxHistory > 0 {
+		rotated, err := hdlr.params.Database.
+			RotateChannelMessages(ctx, maxHistory)
+		if err != nil {
+			hdlr.log.Error(
+				"message rotation failed", "error", err,
+			)
+		} else if rotated > 0 {
+			hdlr.log.Info(
+				"rotated old messages",
+				"deleted", rotated,
+			)
+		}
+	}
+
+	orphaned, err := hdlr.params.Database.
+		PruneOrphanedMessages(ctx)
+	if err != nil {
+		hdlr.log.Error(
+			"orphan message cleanup failed",
+			"error", err,
+		)
+	} else if orphaned > 0 {
+		hdlr.log.Info(
+			"pruned orphaned messages",
+			"deleted", orphaned,
+		)
+	}
 }