feat(go-services): discord-go — Go port of discord-rare-monitor

Consumes the Python tracker's /ws/live firehose (subscribed to rare+chat),
classifies rares common/great, posts embeds + relays allegiance chat.

- classify.go: the 74-name common-rares set, extracted verbatim from the Python
  COMMON_RARES_PATTERN (not hand-transcribed). go test runs at build time; a
  server-side dump-rares vs the Python regex confirms the sets are IDENTICAL.
- poster.go: a `poster` interface with a real discordgo impl (REST sends by
  channel id; gold/blue embeds, location/time fields, icon attachment) and a
  dry-run log impl.
- ws.go: coder/websocket client to /ws/live with subscribe, ping keepalive,
  exponential-backoff reconnect; rare/chat dispatch incl. vortex-warning + the
  MONITOR_CHARACTER filter.
- SAFE BY DEFAULT: dry-run unless a token AND DRY_RUN=0 are set, so it can never
  double-post to production. Deployed via the compose override
  (discord-rare-monitor-go), running dry-run against the same live firehose.

Validated on the server: connects, subscribes, relays a real chat in dry-run;
classifier parity 74/74 vs the Python regex.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

go-services/discord-go/Dockerfile

@@ -0,0 +1,14 @@
+# Multi-stage build for the Go discord-rare-monitor port. The unit test (rare
+# classification) runs at build time, so a classifier regression fails the build.
+FROM golang:1.25-bookworm AS build
+WORKDIR /src
+COPY . .
+RUN go mod tidy
+RUN go test ./...
+ARG BUILD_VERSION=dev
+RUN CGO_ENABLED=0 GOOS=linux go build -trimpath -ldflags "-s -w" -o /out/discord-go .
+
+# distroless/static includes CA certificates (needed for Discord's HTTPS REST API).
+FROM gcr.io/distroless/static-debian12:nonroot
+COPY --from=build /out/discord-go /discord-go
+ENTRYPOINT ["/discord-go"]

go-services/discord-go/classify.go

@@ -0,0 +1,93 @@
+package main
+
+// Rare classification — a faithful port of discord_rare_monitor.py's
+// COMMON_RARES_PATTERN (an anchored exact-match regex of common-rare names).
+// Because the regex is fully anchored with no wildcards, an exact-match set is
+// equivalent. This list was extracted verbatim from the Python source, not
+// hand-transcribed. classify_test.go asserts every entry maps to "common".
+//
+// classify returns "common" for an exact match, "great" otherwise — identical
+// to classify_rare().
+func classify(rareName string) string {
+	if commonRares[rareName] {
+		return "common"
+	}
+	return "great"
+}
+
+var commonRares = map[string]bool{
+	"Alchemist's Crystal":       true,
+	"Scholar's Crystal":         true,
+	"Smithy's Crystal":          true,
+	"Hunter's Crystal":          true,
+	"Observer's Crystal":        true,
+	"Thorsten's Crystal":        true,
+	"Elysa's Crystal":           true,
+	"Chef's Crystal":            true,
+	"Enchanter's Crystal":       true,
+	"Oswald's Crystal":          true,
+	"Deceiver's Crystal":        true,
+	"Fletcher's Crystal":        true,
+	"Physician's Crystal":       true,
+	"Artificer's Crystal":       true,
+	"Tinker's Crystal":          true,
+	"Vaulter's Crystal":         true,
+	"Monarch's Crystal":         true,
+	"Life Giver's Crystal":      true,
+	"Thief's Crystal":           true,
+	"Adherent's Crystal":        true,
+	"Resister's Crystal":        true,
+	"Imbuer's Crystal":          true,
+	"Converter's Crystal":       true,
+	"Evader's Crystal":          true,
+	"Dodger's Crystal":          true,
+	"Zefir's Crystal":           true,
+	"Ben Ten's Crystal":         true,
+	"Corruptor's Crystal":       true,
+	"Artist's Crystal":          true,
+	"T'ing's Crystal":           true,
+	"Warrior's Crystal":         true,
+	"Brawler's Crystal":         true,
+	"Hieromancer's Crystal":     true,
+	"Rogue's Crystal":           true,
+	"Berzerker's Crystal":       true,
+	"Knight's Crystal":          true,
+	"Lugian's Pearl":            true,
+	"Ursuin's Pearl":            true,
+	"Wayfarer's Pearl":          true,
+	"Sprinter's Pearl":          true,
+	"Magus's Pearl":             true,
+	"Lich's Pearl":              true,
+	"Warrior's Jewel":           true,
+	"Melee's Jewel":             true,
+	"Mage's Jewel":              true,
+	"Duelist's Jewel":           true,
+	"Archer's Jewel":            true,
+	"Tusker's Jewel":            true,
+	"Olthoi's Jewel":            true,
+	"Inferno's Jewel":           true,
+	"Gelid's Jewel":             true,
+	"Astyrrian's Jewel":         true,
+	"Executor's Jewel":          true,
+	"Pearl of Blood Drinking":   true,
+	"Pearl of Heart Seeking":    true,
+	"Pearl of Defending":        true,
+	"Pearl of Swift Killing":    true,
+	"Pearl of Spirit Drinking":  true,
+	"Pearl of Hermetic Linking": true,
+	"Pearl of Blade Baning":     true,
+	"Pearl of Pierce Baning":    true,
+	"Pearl of Bludgeon Baning":  true,
+	"Pearl of Acid Baning":      true,
+	"Pearl of Flame Baning":     true,
+	"Pearl of Frost Baning":     true,
+	"Pearl of Lightning Baning": true,
+	"Pearl of Impenetrability":  true,
+	"Refreshing Elixir":         true,
+	"Invigorating Elixir":       true,
+	"Miraculous Elixir":         true,
+	"Medicated Health Kit":      true,
+	"Medicated Stamina Kit":     true,
+	"Medicated Mana Kit":        true,
+	"Casino Exquisite Keyring":  true,
+}

go-services/discord-go/classify_test.go

@@ -0,0 +1,38 @@
+package main
+
+import "testing"
+
+// Every name in the common-rares set must classify as "common".
+func TestClassifyCommon(t *testing.T) {
+	if len(commonRares) != 74 {
+		t.Fatalf("expected 74 common rares, got %d", len(commonRares))
+	}
+	for name := range commonRares {
+		if got := classify(name); got != "common" {
+			t.Errorf("classify(%q) = %q, want common", name, got)
+		}
+	}
+}
+
+// Names not in the set (including near-misses) must classify as "great".
+func TestClassifyGreat(t *testing.T) {
+	greats := []string{
+		"Shimmering Skeleton Key",
+		"Star of Tukal",
+		"Hieroglyph of the Bludgeoner",
+		"Infinite Phial of Pyreal Flux",
+		"Foolproof Hooks",
+		"Staff of All Aphus",
+		"Count Renari's Equctioneer",
+		"Gelidite Long Sword",
+		"Pearl of Blade Baning ", // trailing space — not an exact match
+		"alchemist's crystal",    // wrong case — not an exact match
+		"Alchemist's Crystals",   // plural — not an exact match
+		"",
+	}
+	for _, name := range greats {
+		if got := classify(name); got != "great" {
+			t.Errorf("classify(%q) = %q, want great", name, got)
+		}
+	}
+}

go-services/discord-go/go.mod

@@ -0,0 +1,3 @@
+module git.snakedesert.se/SawatoMosswartsEnjoyersClub/MosswartOverlord/go-services/discord-go
+
+go 1.25

go-services/discord-go/main.go

@@ -0,0 +1,90 @@
+// Command discord-go is a Go port of discord-rare-monitor: it consumes the
+// tracker's /ws/live firehose (subscribed to rare+chat), classifies rares
+// common/great, posts embeds to Discord, and relays allegiance chat.
+//
+// SAFETY: it runs in dry-run (log only, no Discord posts) by default. Going live
+// requires BOTH a bot token AND DRY_RUN=0 — so it can never accidentally
+// double-post to the production channels during the parallel run. For a parallel
+// test, set a TEST token + TEST channel IDs + DRY_RUN=0.
+package main
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"os"
+	"os/signal"
+	"sort"
+	"syscall"
+
+	"github.com/bwmarrin/discordgo"
+)
+
+func main() {
+	// `discord-go dump-rares` prints the common-rares set (for parity diffing
+	// against the Python regex). No network, no token.
+	if len(os.Args) > 1 && os.Args[1] == "dump-rares" {
+		names := make([]string, 0, len(commonRares))
+		for n := range commonRares {
+			names = append(names, n)
+		}
+		sort.Strings(names)
+		for _, n := range names {
+			fmt.Println(n)
+		}
+		return
+	}
+
+	logger := slog.New(slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{Level: slog.LevelInfo}))
+	slog.SetDefault(logger)
+
+	token := os.Getenv("DISCORD_RARE_BOT_TOKEN")
+	// Dry-run unless a token is present AND DRY_RUN is explicitly "0".
+	dryRun := token == "" || os.Getenv("DRY_RUN") != "0"
+
+	wsURL := envOr("DERETH_TRACKER_WS_URL", "ws://dereth-tracker:8765/ws/live")
+	monitorChar := envOr("MONITOR_CHARACTER", "Dunking Rares")
+
+	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
+	defer stop()
+
+	var out poster
+	if dryRun {
+		reason := "no DISCORD_RARE_BOT_TOKEN"
+		if token != "" {
+			reason = "DRY_RUN != 0"
+		}
+		logger.Info("starting in DRY-RUN — classifying but NOT posting to Discord", "reason", reason, "ws", wsURL, "monitor", monitorChar)
+		out = &logPoster{log: logger}
+	} else {
+		dg, err := discordgo.New("Bot " + token)
+		if err != nil {
+			logger.Error("discord session init failed", "err", err)
+			os.Exit(1)
+		}
+		// REST-only: we send by channel ID, so no gateway Open()/intents needed.
+		logger.Info("starting LIVE — posting to Discord", "ws", wsURL, "monitor", monitorChar)
+		out = &discordPoster{
+			dg:       dg,
+			common:   envOr("COMMON_RARE_CHANNEL_ID", "1355328792184226014"),
+			great:    envOr("GREAT_RARE_CHANNEL_ID", "1353676584334131211"),
+			aclog:    envOr("ACLOG_CHANNEL_ID", "1349649482786275328"),
+			sawato:   envOr("SAWATOLIFE_CHANNEL_ID", "1387323032271327423"),
+			iconsDir: envOr("ICONS_DIR", "icons"),
+			log:      logger,
+		}
+	}
+
+	b := &bot{wsURL: wsURL, monitorChar: monitorChar, out: out, log: logger}
+	go b.run(ctx)
+
+	<-ctx.Done()
+	logger.Info("shutdown signal received")
+}
+
+func envOr(key, def string) string {
+	if v := os.Getenv(key); v != "" {
+		return v
+	}
+	return def
+}

go-services/discord-go/poster.go

@@ -0,0 +1,166 @@
+package main
+
+import (
+	"fmt"
+	"log/slog"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/bwmarrin/discordgo"
+)
+
+// Discord embed colors, matching discord.py's Color.gold()/Color.blue().
+const (
+	colorGold = 0xf1c40f
+	colorBlue = 0x3498db
+	colorRed  = 0xe74c3c
+)
+
+type rareEvent struct {
+	Name          string
+	CharacterName string
+	Timestamp     string
+	EW, NS, Z     *float64
+}
+
+// poster abstracts where messages go: a real Discord session, or a dry-run
+// logger used for parallel validation without a bot token / live channels.
+type poster interface {
+	postRare(ev rareEvent, tier string)
+	postChat(charName, text, ts string)
+	postVortex(speaker, text, ts string)
+	postStatus(text string)
+}
+
+// ---- dry-run (log-only) ----
+
+type logPoster struct{ log *slog.Logger }
+
+func (p *logPoster) postRare(ev rareEvent, tier string) {
+	p.log.Info("DRY-RUN would post rare", "tier", tier, "channel", tier, "name", ev.Name, "character", ev.CharacterName)
+}
+func (p *logPoster) postChat(charName, text, ts string) {
+	p.log.Info("DRY-RUN would relay chat", "character", charName, "text", text)
+}
+func (p *logPoster) postVortex(speaker, text, ts string) {
+	p.log.Warn("DRY-RUN would post vortex warning", "speaker", speaker, "text", text)
+}
+func (p *logPoster) postStatus(text string) {
+	p.log.Info("DRY-RUN would post status", "text", text)
+}
+
+// ---- real Discord ----
+
+type discordPoster struct {
+	dg       *discordgo.Session
+	common   string
+	great    string
+	aclog    string
+	sawato   string
+	iconsDir string
+	log      *slog.Logger
+}
+
+func (p *discordPoster) postRare(ev rareEvent, tier string) {
+	embed := buildRareEmbed(ev, tier)
+	channel := p.common
+	if tier == "great" {
+		channel = p.great
+	}
+	if iconPath := p.iconPath(ev.Name); iconPath != "" {
+		if f, err := os.Open(iconPath); err == nil {
+			defer f.Close()
+			fn := filepath.Base(iconPath)
+			embed.Image = &discordgo.MessageEmbedImage{URL: "attachment://" + fn}
+			if _, err := p.dg.ChannelMessageSendComplex(channel, &discordgo.MessageSend{
+				Embed: embed,
+				Files: []*discordgo.File{{Name: fn, Reader: f}},
+			}); err != nil {
+				p.log.Error("send rare embed (with icon) failed", "err", err, "channel", channel)
+			}
+			return
+		}
+	}
+	if _, err := p.dg.ChannelMessageSendEmbed(channel, embed); err != nil {
+		p.log.Error("send rare embed failed", "err", err, "channel", channel)
+	}
+}
+
+func (p *discordPoster) postChat(charName, text, ts string) {
+	t := parseTime(ts)
+	cleaned := strings.TrimPrefix(text, "Dunking Rares: ")
+	msg := fmt.Sprintf("`%s` %s", t.Format("15:04:05"), cleaned)
+	if _, err := p.dg.ChannelMessageSend(p.sawato, msg); err != nil {
+		p.log.Error("send chat failed", "err", err)
+	}
+}
+
+func (p *discordPoster) postVortex(speaker, text, ts string) {
+	embed := &discordgo.MessageEmbed{
+		Title:       "🌪️ VORTEX WARNING",
+		Description: fmt.Sprintf("**%s**: %s", speaker, text),
+		Color:       colorRed,
+		Timestamp:   parseTime(ts).Format(time.RFC3339),
+	}
+	if _, err := p.dg.ChannelMessageSendEmbed(p.aclog, embed); err != nil {
+		p.log.Error("send vortex failed", "err", err)
+	}
+}
+
+func (p *discordPoster) postStatus(text string) {
+	if _, err := p.dg.ChannelMessageSend(p.aclog, text); err != nil {
+		p.log.Error("send status failed", "err", err)
+	}
+}
+
+func (p *discordPoster) iconPath(rareName string) string {
+	if p.iconsDir == "" {
+		return ""
+	}
+	fn := strings.NewReplacer("'", "", " ", "_", "-", "_").Replace(rareName) + "_Icon.png"
+	path := filepath.Join(p.iconsDir, fn)
+	if _, err := os.Stat(path); err == nil {
+		return path
+	}
+	return ""
+}
+
+// buildRareEmbed mirrors post_rare_to_discord's embed.
+func buildRareEmbed(ev rareEvent, tier string) *discordgo.MessageEmbed {
+	title, color := "🔸 Common Rare Discovery", colorBlue
+	if tier == "great" {
+		title, color = "💎 Great Rare Discovery!", colorGold
+	}
+	t := parseTime(ev.Timestamp)
+	embed := &discordgo.MessageEmbed{
+		Title:       title,
+		Description: fmt.Sprintf("**%s** has discovered the **%s**!", ev.CharacterName, ev.Name),
+		Color:       color,
+		Timestamp:   t.Format(time.RFC3339),
+	}
+	if ev.EW != nil && ev.NS != nil {
+		loc := fmt.Sprintf("%.1fE, %.1fN", *ev.EW, *ev.NS)
+		if ev.Z != nil {
+			loc += fmt.Sprintf(", %.1fZ", *ev.Z)
+		}
+		embed.Fields = append(embed.Fields, &discordgo.MessageEmbedField{Name: "📍 Location", Value: loc, Inline: true})
+	}
+	embed.Fields = append(embed.Fields, &discordgo.MessageEmbedField{
+		Name: "⏰ Time", Value: t.UTC().Format("15:04:05") + " UTC", Inline: true,
+	})
+	return embed
+}
+
+// parseTime accepts the plugin's ISO8601 (with or without 'Z'); falls back to now.
+func parseTime(ts string) time.Time {
+	if ts != "" {
+		for _, layout := range []string{time.RFC3339Nano, time.RFC3339, "2006-01-02T15:04:05.999999", "2006-01-02T15:04:05"} {
+			if t, err := time.Parse(layout, strings.Replace(ts, "Z", "+00:00", 1)); err == nil {
+				return t
+			}
+		}
+	}
+	return time.Now().UTC()
+}

go-services/discord-go/ws.go

@@ -0,0 +1,159 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"log/slog"
+	"strings"
+	"time"
+
+	"github.com/coder/websocket"
+)
+
+// bot consumes the tracker's /ws/live firehose (subscribed to rare+chat) and
+// routes events to a poster. It reconnects with exponential backoff, mirroring
+// monitor_websocket().
+type bot struct {
+	wsURL       string
+	monitorChar string
+	out         poster
+	log         *slog.Logger
+}
+
+func (b *bot) run(ctx context.Context) {
+	backoff := time.Second
+	const maxBackoff = 60 * time.Second
+	for ctx.Err() == nil {
+		err := b.connectAndConsume(ctx)
+		if ctx.Err() != nil {
+			return
+		}
+		if err != nil {
+			b.log.Warn("ws disconnected; reconnecting", "err", err, "backoff", backoff.String())
+		}
+		select {
+		case <-ctx.Done():
+			return
+		case <-time.After(backoff):
+		}
+		backoff *= 2
+		if backoff > maxBackoff {
+			backoff = maxBackoff
+		}
+	}
+}
+
+func (b *bot) connectAndConsume(ctx context.Context) error {
+	b.log.Info("connecting to /ws/live", "url", b.wsURL)
+	c, _, err := websocket.Dial(ctx, b.wsURL, nil)
+	if err != nil {
+		return err
+	}
+	defer c.CloseNow()
+	c.SetReadLimit(8 << 20) // payloads (nearby_objects etc.) can be large; we only read rare/chat but the socket carries all
+
+	// Subscribe to just rare + chat (server-side filtering), like the Python bot.
+	sub, _ := json.Marshal(map[string]any{"type": "subscribe", "message_types": []string{"rare", "chat"}})
+	if err := c.Write(ctx, websocket.MessageText, sub); err != nil {
+		return err
+	}
+	b.log.Info("subscribed", "message_types", []string{"rare", "chat"})
+	b.out.postStatus("🔗 (go) WebSocket connection established")
+
+	// Keepalive pings, like ping_interval=20.
+	pingCtx, cancel := context.WithCancel(ctx)
+	defer cancel()
+	go func() {
+		t := time.NewTicker(20 * time.Second)
+		defer t.Stop()
+		for {
+			select {
+			case <-pingCtx.Done():
+				return
+			case <-t.C:
+				pc, cc := context.WithTimeout(pingCtx, 10*time.Second)
+				_ = c.Ping(pc)
+				cc()
+			}
+		}
+	}()
+
+	for {
+		_, data, err := c.Read(ctx)
+		if err != nil {
+			return err
+		}
+		b.handleMessage(data)
+	}
+}
+
+func (b *bot) handleMessage(raw []byte) {
+	var data map[string]any
+	if err := json.Unmarshal(raw, &data); err != nil {
+		return // ignore invalid JSON, like the Python bot
+	}
+	switch asString(data["type"]) {
+	case "rare":
+		b.handleRare(data)
+	case "chat":
+		b.handleChat(data)
+	}
+}
+
+func (b *bot) handleRare(data map[string]any) {
+	ev := rareEvent{
+		Name:          asStringOr(data["name"], "Unknown Rare"),
+		CharacterName: asStringOr(data["character_name"], "Unknown Character"),
+		Timestamp:     asString(data["timestamp"]),
+		EW:            asFloatPtr(data["ew"]),
+		NS:            asFloatPtr(data["ns"]),
+		Z:             asFloatPtr(data["z"]),
+	}
+	tier := classify(ev.Name)
+	b.log.Info("rare", "name", ev.Name, "character", ev.CharacterName, "tier", tier)
+	b.out.postRare(ev, tier)
+}
+
+func (b *bot) handleChat(data map[string]any) {
+	charName := asString(data["character_name"])
+	text := asString(data["text"])
+	if charName != b.monitorChar {
+		return
+	}
+	if strings.Contains(text, "m in whirlwind of vortexes") {
+		b.out.postVortex(parseAllegianceSpeaker(text), text, asString(data["timestamp"]))
+		return
+	}
+	b.out.postChat(charName, text, asString(data["timestamp"]))
+}
+
+// parseAllegianceSpeaker extracts <name> from "[Allegiance] <name> says, ...".
+func parseAllegianceSpeaker(text string) string {
+	const prefix = "[Allegiance] "
+	if i := strings.Index(text, prefix); i >= 0 {
+		rest := text[i+len(prefix):]
+		if j := strings.Index(rest, " says,"); j >= 0 {
+			return rest[:j]
+		}
+	}
+	return "Unknown"
+}
+
+func asString(v any) string {
+	s, _ := v.(string)
+	return s
+}
+
+func asStringOr(v any, def string) string {
+	if s, ok := v.(string); ok && s != "" {
+		return s
+	}
+	return def
+}
+
+func asFloatPtr(v any) *float64 {
+	if f, ok := v.(float64); ok {
+		return &f
+	}
+	return nil
+}

go-services/docker-compose.go.yml

@@ -42,3 +42,33 @@ services:
       options:
         max-size: "10m"
         max-file: "3"
+
+  # Go port of discord-rare-monitor. Consumes the SAME Python /ws/live firehose
+  # as the live Python bot. DRY-RUN by default (logs classifications, posts
+  # nothing) so it can't double-post. To parallel-test for real, set a TEST
+  # DISCORD_RARE_BOT_TOKEN + TEST channel IDs + DRY_RUN=0 here.
+  discord-rare-monitor-go:
+    build:
+      context: ./go-services/discord-go
+      args:
+        BUILD_VERSION: ${BUILD_VERSION:-dev}
+    container_name: discord-rare-monitor-go
+    environment:
+      DERETH_TRACKER_WS_URL: "ws://dereth-tracker:8765/ws/live"
+      MONITOR_CHARACTER: "Dunking Rares"
+      ICONS_DIR: "/icons"
+      LOG_LEVEL: "INFO"
+      # DISCORD_RARE_BOT_TOKEN: ""   # set a TEST token to go live
+      # DRY_RUN: "0"                 # required (with a token) to actually post
+      # COMMON_RARE_CHANNEL_ID / GREAT_RARE_CHANNEL_ID / SAWATOLIFE_CHANNEL_ID /
+      # ACLOG_CHANNEL_ID: set TEST channels before going live
+    volumes:
+      - ./discord-rare-monitor/icons:/icons:ro
+    depends_on:
+      - dereth-tracker
+    restart: unless-stopped
+    logging:
+      driver: "json-file"
+      options:
+        max-size: "10m"
+        max-file: "3"