refactor(backend): drop backend-driven Fabric broadcast — agent-driven model

The backend no longer broadcasts topic lifecycle events to Fabric. The
new model (per design discussion 2026-05-23 evening):

  - Proposing agent posts a single recruitment fabric-send-message
    immediately after creating a topic (carries topic_id + signup
    window + debate window + title).
  - Downstream agents that decide to participate book a HF on_call
    slot covering the debate window via `hf calendar schedule on_call
    <time> <duration> --job DEBATE-<topic_id>`.
  - HF wakes the agent naturally at slot start; the wake payload
    carries event_data with the DEBATE-<topic_id> code so the agent
    knows why it was woken.
  - The backend stays a pure data + state-machine service and doesn't
    know about Fabric.

Code removed:

  - internal/fabric/announce.go (entire file + empty dir)
  - ticker.go: broadcastLifecycle + broadcastAnnouncement + topicTarget
    helpers; announcer field on Ticker; announce field/arg on NewTicker
  - models/topic.go: AnnounceGuildBaseURL + AnnounceChannelID fields
  - store/topic_store.go: same fields on CreateTopicInput + INSERT
  - handlers/topics.go: same fields on createTopicBody + validation +
    parameter passing to store
  - handlers/verdict.go: announcer field + lifecycle broadcast on
    verdict submit
  - config/config.go: FabricSystemAPIKey field + DIALECTIC_FABRIC_SYSTEM_API_KEY
    env read
  - main.go + routes.go: announcer wiring

Database:

  - migrations/003_drop_topic_announce_target.sql drops the two columns
    added by migration 002. Counterpart commit on the deployment side
    needs DIALECTIC_FABRIC_SYSTEM_API_KEY env removed from
    docker-compose.yml; harmless if left as the backend no longer
    reads it.

Pairs with:
  - Dialectic.OpenclawPlugin: rip announce_* params from
    dialectic_propose_topic (next commit)
  - Fabric.Backend.Center: rip serviceEndpoint field + cli
  - Fabric.Backend.Guild: rip system-key bypass on ApiKeyGuard and
    announce-only-system limit on messaging.controller
  - ClawSkills: rewrite participate-debate + analyze-intel step 4 +
    delete rotate-fabric-system-key workflow

internal/config/config.go

@@ -66,24 +66,14 @@ type Config struct {
 	OIDCIssuer   string
 	OIDCClientID string
 
-	// Fabric announce coupling.
+	// (Removed Aug 2026: all Fabric coupling — FabricSystemAPIKey,
-	//
+	// FabricGuildBaseURL, FabricAnnounceChannelID, FabricBotBearerToken.
-	// As of Phase 3.5: only the system api key stays in env. Guild base
+	// Backend no longer broadcasts lifecycle events to Fabric. The
-	// URL + announce channel ID are PER-TOPIC, supplied by the proposing
+	// proposing agent posts a single recruitment fabric-send-message
-	// agent at create time and stored on the topic row. Different topics
+	// after creating a topic; downstream agents book HF on_call slots
-	// can broadcast to different guilds/channels from the same backend.
+	// covering the debate window via `hf calendar schedule` and HF
-	//
+	// wakes them naturally. The backend stays a pure data + state-
-	// FabricSystemAPIKey: header value for x-fabric-system-key when
+	// machine service and doesn't know about Fabric.)
-	// POSTing to announce channels. Must match Fabric.Backend.Guild's
-	// FABRIC_BACKEND_GUILD_SYSTEM_API_KEY env. Empty → announcer becomes
-	// a no-op (logs intent, skips post — useful for dev / opted-out
-	// environments).
-	FabricSystemAPIKey string
-
-	// (removed Phase 3.5: FabricGuildBaseURL, FabricAnnounceChannelID,
-	// FabricBotBearerToken — guild/channel moved to per-topic config;
-	// bot bearer obsolete since Guild's ApiKeyGuard now accepts system
-	// key alone for announce posts.)
 
 	// Orchestrator tick interval. 0 / unset → default 15s.
 	OrchestratorTickInterval time.Duration
@@ -105,7 +95,6 @@ func LoadFromEnv() (*Config, error) {
 		DialecticAdminAPIKey: os.Getenv("DIALECTIC_ADMIN_API_KEY"),
 		OIDCIssuer:           os.Getenv("OIDC_ISSUER"),
 		OIDCClientID:         os.Getenv("OIDC_CLIENT_ID"),
-		FabricSystemAPIKey:   os.Getenv("DIALECTIC_FABRIC_SYSTEM_API_KEY"),
 	}
 	if d := os.Getenv("ORCHESTRATOR_TICK_INTERVAL"); d != "" {
 		if parsed, err := time.ParseDuration(d); err == nil {

internal/db/migrations/003_drop_topic_announce_target.sql

@@ -0,0 +1,10 @@
+-- Drop per-topic announce target columns. The backend no longer
+-- broadcasts lifecycle events to Fabric; the proposing agent posts a
+-- single recruitment fabric-send-message after topic creation, and
+-- downstream agents book HF on_call slots covering the debate window
+-- via `hf calendar schedule` so HF wakes them naturally.
+--
+-- Counterpart of 002_topic_announce_target.sql (now obsolete).
+ALTER TABLE topics
+  DROP COLUMN announce_guild_base_url,
+  DROP COLUMN announce_channel_id;

internal/fabric/announce.go

@@ -1,131 +0,0 @@
-// Package fabric provides an HTTP client for posting system messages
-// to a Fabric Guild's announce-type channel.
-//
-// As of Phase 3.5 the target (guildBaseUrl + channelID) is per-call
-// rather than backend-env: each topic stores its own announce target,
-// chosen by the proposing agent at create time. Only the system api
-// key stays in backend env (DIALECTIC_FABRIC_SYSTEM_API_KEY) since it
-// authorizes ANY announce POST regardless of channel.
-//
-// FABRIC_BOT_BEARER_TOKEN is gone — the upgraded Fabric.Backend.Guild
-// ApiKeyGuard accepts x-fabric-system-key alone (no per-user Bearer
-// required) for announce-channel posts.
-package fabric
-
-import (
-	"bytes"
-	"context"
-	"encoding/json"
-	"fmt"
-	"io"
-	"log"
-	"net/http"
-	"time"
-)
-
-type Announcer struct {
-	systemAPIKey   string
-	requestTimeout time.Duration
-	client         *http.Client
-}
-
-func NewAnnouncer(systemAPIKey string) *Announcer {
-	timeout := 5 * time.Second
-	return &Announcer{
-		systemAPIKey:   systemAPIKey,
-		requestTimeout: timeout,
-		client:         &http.Client{Timeout: timeout},
-	}
-}
-
-// Enabled returns true iff the system api key is configured (without
-// it, no announce POST can authenticate).
-func (a *Announcer) Enabled() bool { return a.systemAPIKey != "" }
-
-// Target identifies one announce post destination. Both fields must
-// be non-empty; either empty -> Post* returns a "skipped" no-op.
-type Target struct {
-	GuildBaseURL string
-	ChannelID    string
-}
-
-// PostTopicAnnouncement: first signup-open broadcast.
-// PostLifecycleEvent: subsequent state transitions.
-//
-// Both best-effort: log + nil on transport / target-misconfigured
-// errors so the orchestrator transition isn't blocked by a Fabric
-// outage or an opted-out topic.
-
-func (a *Announcer) PostTopicAnnouncement(ctx context.Context, t Target,
-	topicID, title, summary string,
-	signupOpen, signupClose, debateStart, debateEnd time.Time,
-	verdictSchemaID string) error {
-
-	body := formatAnnouncement(topicID, title, summary,
-		signupOpen, signupClose, debateStart, debateEnd, verdictSchemaID)
-	return a.post(ctx, t, topicID, "signup_open", body)
-}
-
-func (a *Announcer) PostLifecycleEvent(ctx context.Context, t Target,
-	topicID, title, kind, summary string) error {
-	body := fmt.Sprintf("📣 **[%s]** %s [%s]\n%s", kind, title, topicID, summary)
-	return a.post(ctx, t, topicID, kind, body)
-}
-
-func (a *Announcer) post(ctx context.Context, t Target, topicID, kind, content string) error {
-	if !a.Enabled() {
-		log.Printf("announce: skipped topic=%s kind=%s — DIALECTIC_FABRIC_SYSTEM_API_KEY unset", topicID, kind)
-		return nil
-	}
-	if t.GuildBaseURL == "" || t.ChannelID == "" {
-		log.Printf("announce: skipped topic=%s kind=%s — no announce target on topic (creator opted out)", topicID, kind)
-		return nil
-	}
-
-	body, _ := json.Marshal(map[string]any{"content": content})
-	url := fmt.Sprintf("%s/api/channels/%s/messages",
-		trimRightSlash(t.GuildBaseURL), t.ChannelID)
-	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(body))
-	if err != nil {
-		return err
-	}
-	req.Header.Set("content-type", "application/json")
-	req.Header.Set("x-fabric-system-key", a.systemAPIKey)
-
-	resp, err := a.client.Do(req)
-	if err != nil {
-		log.Printf("announce: POST %s failed: %v", url, err)
-		return err
-	}
-	defer resp.Body.Close()
-	if resp.StatusCode >= 300 {
-		b, _ := io.ReadAll(io.LimitReader(resp.Body, 1024))
-		log.Printf("announce: POST %s kind=%s -> %d body=%s", url, kind, resp.StatusCode, string(b))
-		return fmt.Errorf("announce post: status %d", resp.StatusCode)
-	}
-	return nil
-}
-
-func formatAnnouncement(id, title, summary string,
-	signupOpen, signupClose, debateStart, debateEnd time.Time, schema string) string {
-	const layout = "2006-01-02 15:04 UTC"
-	return fmt.Sprintf(
-		"🆕 **Debate signup open** [%s]\n\n**%s**\n%s\n\n"+
-			"• Signup: %s → %s\n"+
-			"• Debate: %s → %s\n"+
-			"• Verdict schema: `%s`\n\n"+
-			"To volunteer, use the `dialectic_signup` tool with this topic_id and your willing camp(s) — pro / con / judge. "+
-			"You must have an `on_call` slot covering the debate window.",
-		id, title, summary,
-		signupOpen.UTC().Format(layout), signupClose.UTC().Format(layout),
-		debateStart.UTC().Format(layout), debateEnd.UTC().Format(layout),
-		schema,
-	)
-}
-
-func trimRightSlash(s string) string {
-	for len(s) > 0 && s[len(s)-1] == '/' {
-		s = s[:len(s)-1]
-	}
-	return s
-}

internal/httpapi/handlers/topics.go

@@ -109,12 +109,6 @@ type createTopicBody struct {
 	SignupCloseAt   string `json:"signup_close_at"`
 	DebateStartAt   string `json:"debate_start_at"`
 	DebateEndAt     string `json:"debate_end_at"`
-	// Optional: per-topic announce-channel target. Both must be set
-	// (or both omitted = no broadcasts). Creator picks based on the
-	// debate's intended audience (different guilds may host different
-	// communities, different channels may serve different categories).
-	AnnounceGuildBaseURL string `json:"announce_guild_base_url,omitempty"`
-	AnnounceChannelID    string `json:"announce_channel_id,omitempty"`
 }
 
 // POST /api/topics
@@ -147,19 +141,6 @@ func (h *TopicsHandler) Create(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, err.Error(), http.StatusBadRequest)
 		return
 	}
-	// Announce target: both fields required or both empty; one-of-two
-	// is a config error caught here rather than silently treated as
-	// "no broadcast".
-	var aGuild, aChannel *string
-	if body.AnnounceGuildBaseURL != "" || body.AnnounceChannelID != "" {
-		if body.AnnounceGuildBaseURL == "" || body.AnnounceChannelID == "" {
-			http.Error(w, "announce_guild_base_url and announce_channel_id must both be set (or both empty for no broadcasts)", http.StatusBadRequest)
-			return
-		}
-		g, c := body.AnnounceGuildBaseURL, body.AnnounceChannelID
-		aGuild, aChannel = &g, &c
-	}
-
 	created, err := h.store.Create(r.Context(), store.CreateTopicInput{
 		Title:           body.Title,
 		Summary:         body.Summary,
@@ -170,8 +151,6 @@ func (h *TopicsHandler) Create(w http.ResponseWriter, r *http.Request) {
 		DebateStartAt:   parsed[2],
 		DebateEndAt:     parsed[3],
 		CreatorUserID:   caller.ID,
-		AnnounceGuildBaseURL: aGuild,
-		AnnounceChannelID:    aChannel,
 	})
 	if err != nil {
 		http.Error(w, "create failed: "+err.Error(), http.StatusInternalServerError)

internal/httpapi/handlers/verdict.go

@@ -1,17 +1,14 @@
 package handlers
 
 import (
-	"context"
 	"encoding/json"
 	"errors"
-	"fmt"
 	"net/http"
 	"time"
 
 	"github.com/go-chi/chi/v5"
 
 	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/auth"
-	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/fabric"
 	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/models"
 	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/store"
 )
@@ -20,11 +17,10 @@ type VerdictHandler struct {
 	topics   *store.TopicStore
 	camps    *store.CampStore
 	verdicts *store.VerdictStore
-	announcer *fabric.Announcer // optional; nil-safe via Enabled() check
 }
 
-func NewVerdictHandler(t *store.TopicStore, c *store.CampStore, v *store.VerdictStore, ann *fabric.Announcer) *VerdictHandler {
+func NewVerdictHandler(t *store.TopicStore, c *store.CampStore, v *store.VerdictStore) *VerdictHandler {
-	return &VerdictHandler{topics: t, camps: c, verdicts: v, announcer: ann}
+	return &VerdictHandler{topics: t, camps: c, verdicts: v}
 }
 
 type submitVerdictBody struct {
@@ -117,24 +113,6 @@ func (h *VerdictHandler) Submit(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("x-warn", "verdict saved but status update failed: "+err.Error())
 	}
 
-	// Lifecycle broadcast — completed event. Best-effort; runs async
-	// outside the request context so a slow Fabric doesn't slow the
-	// judge's response. Target is per-topic (nil announcer or nil
-	// target on topic → silently skipped by announcer).
-	if h.announcer != nil {
-		var tgt fabric.Target
-		if topic.AnnounceGuildBaseURL != nil && topic.AnnounceChannelID != nil {
-			tgt = fabric.Target{
-				GuildBaseURL: *topic.AnnounceGuildBaseURL,
-				ChannelID:    *topic.AnnounceChannelID,
-			}
-		}
-		go func(t *fabric.Announcer, tID, title, judge string, target fabric.Target) {
-			summary := fmt.Sprintf("verdict published by judge=%s. Use dialectic_view_verdict to see the structured result.", judge)
-			_ = t.PostLifecycleEvent(context.Background(), target, tID, title, "completed", summary)
-		}(h.announcer, verdict.TopicID, topic.Title, caller.ID, tgt)
-	}
-
 	writeJSON(w, http.StatusCreated, map[string]any{
 		"id":             verdict.ID,
 		"topic_id":       verdict.TopicID,

internal/httpapi/routes.go

@@ -11,7 +11,6 @@ import (
 
 	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/auth"
 	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/config"
-	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/fabric"
 	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/httpapi/handlers"
 	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/store"
 )
@@ -63,8 +62,7 @@ func Mount(cfg *config.Config, db *sqlx.DB, version string) http.Handler {
 	topicsH := handlers.NewTopicsHandler(topicStore, campStore)
 	signupsH := handlers.NewSignupsHandler(topicStore, signupStore)
 	argsH := handlers.NewArgumentsHandler(topicStore, campStore, roundStore, argStore)
-	announcer := fabric.NewAnnouncer(cfg.FabricSystemAPIKey)
+	verdictH := handlers.NewVerdictHandler(topicStore, campStore, verdictStore)
-	verdictH := handlers.NewVerdictHandler(topicStore, campStore, verdictStore, announcer)
 	adminH := handlers.NewAdminHandler(db, cfg.AgentAPIKeyPepper, cfg.DialecticAdminAPIKey)
 
 	// Routes.

internal/models/topic.go

@@ -49,13 +49,6 @@ type Topic struct {
 	VisibilityChangedBy *string     `db:"visibility_changed_by" json:"visibility_changed_by,omitempty"`
 	VisibilityChangedAt *time.Time  `db:"visibility_changed_at" json:"visibility_changed_at,omitempty"`
 	CancelledReason     *string     `db:"cancelled_reason" json:"cancelled_reason,omitempty"`
-	// AnnounceGuildBaseURL + AnnounceChannelID: per-topic broadcast
-	// target. Set by the proposing agent at create time (they pick which
-	// Fabric guild + announce channel reflects this topic's audience).
-	// Both nullable; null on either side disables lifecycle broadcasts
-	// for this topic (creator opted out).
-	AnnounceGuildBaseURL *string   `db:"announce_guild_base_url" json:"announce_guild_base_url,omitempty"`
-	AnnounceChannelID    *string   `db:"announce_channel_id" json:"announce_channel_id,omitempty"`
 	CreatedAt           time.Time   `db:"created_at" json:"created_at"`
 	UpdatedAt           time.Time   `db:"updated_at" json:"updated_at"`
 }

internal/orchestrator/ticker.go

@@ -2,14 +2,12 @@ package orchestrator
 
 import (
 	"context"
-	"fmt"
 	"log"
 	"math/rand"
 	"time"
 
 	"github.com/jmoiron/sqlx"
 
-	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/fabric"
 	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/models"
 	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/store"
 )
@@ -21,7 +19,6 @@ import (
 // State transitions handled by the ticker:
 //
 //	created       → signup_open      (when now >= signup_open_at)
-//	                                  + post Fabric announcement
 //	signup_open   → signup_closed    (when now >= signup_close_at, allocator succeeded)
 //	              → cancelled         (allocator returned CancelReason)
 //	signup_closed → debating         (when now >= debate_start_at; opens round 0)
@@ -35,13 +32,19 @@ import (
 //
 // Per-topic transitions use SELECT FOR UPDATE so concurrent ticker
 // instances (or future replicas) don't double-fire.
+//
+// Lifecycle broadcasting moved out-of-backend (Aug 2026): the proposing
+// agent posts a single recruitment fabric-send-message after creating a
+// topic; downstream agents book HF on_call slots covering the debate
+// window via `hf calendar schedule`, and HF wakes them naturally. The
+// backend stays a pure data + state-machine service and doesn't know
+// about Fabric.
 type Ticker struct {
 	db       *sqlx.DB
 	topics   *store.TopicStore
 	signups  *store.SignupStore
 	camps    *store.CampStore
 	rounds   *store.RoundStore
-	announcer *fabric.Announcer
 	interval time.Duration
 	rng      *rand.Rand
 }
@@ -52,7 +55,6 @@ func NewTicker(
 	signups *store.SignupStore,
 	camps *store.CampStore,
 	rounds *store.RoundStore,
-	announcer *fabric.Announcer,
 	interval time.Duration,
 ) *Ticker {
 	if interval <= 0 {
@@ -64,7 +66,6 @@ func NewTicker(
 		signups:  signups,
 		camps:    camps,
 		rounds:   rounds,
-		announcer: announcer,
 		interval: interval,
 		rng:      rand.New(rand.NewSource(time.Now().UnixNano())),
 	}
@@ -72,7 +73,7 @@ func NewTicker(
 
 // Run blocks until ctx is cancelled. Caller goroutines it.
 func (t *Ticker) Run(ctx context.Context) {
-	log.Printf("orchestrator: ticker started (interval=%s, announce=%v)", t.interval, t.announcer.Enabled())
+	log.Printf("orchestrator: ticker started (interval=%s)", t.interval)
 	tk := time.NewTicker(t.interval)
 	defer tk.Stop()
 	// First tick immediately so startup is responsive — don't wait
@@ -81,7 +82,7 @@ func (t *Ticker) Run(ctx context.Context) {
 	for {
 		select {
 		case <-ctx.Done():
-			log.Printf("orchestrator: ticker stopped")
+			log.Printf("orchestrator: ticker stopping")
 			return
 		case <-tk.C:
 			t.tickOnce(ctx)
@@ -89,8 +90,6 @@ func (t *Ticker) Run(ctx context.Context) {
 	}
 }
 
-// tickOnce scans + applies. Errors are logged per topic; one topic
-// failing doesn't stall the others.
 func (t *Ticker) tickOnce(ctx context.Context) {
 	now := time.Now()
 
@@ -98,17 +97,11 @@ func (t *Ticker) tickOnce(ctx context.Context) {
 	if err := t.transitionByStatus(ctx, now,
 		models.TopicStatusCreated, "signup_open_at",
 		func(ctx context.Context, tx *sqlx.Tx, topicID string) error {
-			topic, err := t.topics.GetByID(ctx, topicID)
-			if err != nil {
-				return err
-			}
 			if _, err := tx.ExecContext(ctx,
 				`UPDATE topics SET status = ? WHERE id = ?`,
 				models.TopicStatusSignupOpen, topicID); err != nil {
 				return err
 			}
-			// Announcement is best-effort, outside the tx (network call).
-			go t.broadcastAnnouncement(topic)
 			return nil
 		}); err != nil {
 		log.Printf("orchestrator: created→signup_open scan: %v", err)
@@ -118,10 +111,6 @@ func (t *Ticker) tickOnce(ctx context.Context) {
 	if err := t.transitionByStatus(ctx, now,
 		models.TopicStatusSignupOpen, "signup_close_at",
 		func(ctx context.Context, tx *sqlx.Tx, topicID string) error {
-			topic, err := t.topics.GetByID(ctx, topicID)
-			if err != nil {
-				return err
-			}
 			signups, err := t.signups.ListByTopic(ctx, topicID)
 			if err != nil {
 				return err
@@ -133,10 +122,6 @@ func (t *Ticker) tickOnce(ctx context.Context) {
 					models.TopicStatusCancelled, res.CancelReason, topicID)
 				log.Printf("orchestrator: topic %s cancelled at signup_close: %s",
 					topicID, res.CancelReason)
-				if err == nil {
-					go t.broadcastLifecycle(topic, "cancelled",
-						fmt.Sprintf("debate cancelled at signup close - %s", res.CancelReason))
-				}
 				return err
 			}
 			if err := t.camps.WriteAllocation(ctx, tx, topicID, res.Allocation); err != nil {
@@ -148,14 +133,6 @@ func (t *Ticker) tickOnce(ctx context.Context) {
 			log.Printf("orchestrator: topic %s allocated pro=%s con=%s judge=%s",
 				topicID,
 				res.Allocation[models.CampPro], res.Allocation[models.CampCon], res.Allocation[models.CampJudge])
-			if err == nil {
-				go t.broadcastLifecycle(topic, "signup_closed",
-					fmt.Sprintf("camps allocated — pro=%s con=%s judge=%s. Debate starts at %s",
-						res.Allocation[models.CampPro],
-						res.Allocation[models.CampCon],
-						res.Allocation[models.CampJudge],
-						topic.DebateStartAt.UTC().Format("2006-01-02 15:04 UTC")))
-			}
 			return err
 		}); err != nil {
 		log.Printf("orchestrator: signup_open→signup_closed scan: %v", err)
@@ -165,10 +142,6 @@ func (t *Ticker) tickOnce(ctx context.Context) {
 	if err := t.transitionByStatus(ctx, now,
 		models.TopicStatusSignupClosed, "debate_start_at",
 		func(ctx context.Context, tx *sqlx.Tx, topicID string) error {
-			topic, err := t.topics.GetByID(ctx, topicID)
-			if err != nil {
-				return err
-			}
 			if _, err := tx.ExecContext(ctx,
 				`UPDATE topics SET status = ? WHERE id = ?`,
 				models.TopicStatusDebating, topicID); err != nil {
@@ -176,15 +149,10 @@ func (t *Ticker) tickOnce(ctx context.Context) {
 			}
 			// Round 0 inserted within the tx — if commit fails we don't
 			// leak a half-state.
-			_, err = tx.ExecContext(ctx,
+			_, err := tx.ExecContext(ctx,
 				`INSERT INTO rounds (id, topic_id, round_no) VALUES (UUID(), ?, 0)`,
 				topicID)
 			log.Printf("orchestrator: topic %s entered debating; round 0 opened", topicID)
-			if err == nil {
-				go t.broadcastLifecycle(topic, "debating",
-					fmt.Sprintf("debate is live — pro/con post arguments; judge stays mostly silent until debate_end_at (%s). Use participate-debate workflow.",
-						topic.DebateEndAt.UTC().Format("2006-01-02 15:04 UTC")))
-			}
 			return err
 		}); err != nil {
 		log.Printf("orchestrator: signup_closed→debating scan: %v", err)
@@ -193,10 +161,7 @@ func (t *Ticker) tickOnce(ctx context.Context) {
 	// Note: there's no explicit `debating → judging` transition in v1.
 	// The verdict handler enforces "status==debating AND now>=debate_end_at"
 	// as its preconditions; that's equivalent to a "judging" gate without
-	// adding a new enum value. Migration 002 will introduce the explicit
+	// adding a new enum value.
-	// 'judging' state when we want richer UI (e.g. "Awaiting verdict"
-	// distinct from "In debate"); until then this comment serves as the
-	// state-machine documentation for future maintainers.
 }
 
 // transitionByStatus is the shared "scan + per-row tx + apply" pattern.
@@ -245,48 +210,3 @@ func (t *Ticker) applyOne(ctx context.Context, topicID string,
 	}
 	return tx.Commit()
 }
-
-// broadcastLifecycle wraps the announcer's lifecycle-event post with
-// the standard signup_closed / cancelled / debating / completed
-// formats. Best-effort; runs in its own goroutine outside any tx.
-// Target is resolved from the topic's per-topic announce columns;
-// null on either column → announcer skips with a log (creator opted
-// out of broadcasts).
-func (t *Ticker) broadcastLifecycle(topic *models.Topic, kind, summary string) {
-	if topic == nil {
-		return
-	}
-	if err := t.announcer.PostLifecycleEvent(
-		context.Background(), topicTarget(topic), topic.ID, topic.Title, kind, summary,
-	); err != nil {
-		log.Printf("orchestrator: lifecycle broadcast topic=%s kind=%s failed: %v", topic.ID, kind, err)
-	}
-}
-
-func (t *Ticker) broadcastAnnouncement(topic *models.Topic) {
-	if topic == nil {
-		return
-	}
-	if err := t.announcer.PostTopicAnnouncement(
-		context.Background(), topicTarget(topic),
-		topic.ID, topic.Title, topic.Summary,
-		topic.SignupOpenAt, topic.SignupCloseAt,
-		topic.DebateStartAt, topic.DebateEndAt,
-		topic.VerdictSchemaID,
-	); err != nil {
-		log.Printf("orchestrator: announce topic=%s failed: %v", topic.ID, err)
-	}
-}
-
-// topicTarget extracts the per-topic announce target from the topic
-// row; returns zero-value Target if either column is null (which the
-// announcer treats as "skip").
-func topicTarget(topic *models.Topic) fabric.Target {
-	if topic.AnnounceGuildBaseURL == nil || topic.AnnounceChannelID == nil {
-		return fabric.Target{}
-	}
-	return fabric.Target{
-		GuildBaseURL: *topic.AnnounceGuildBaseURL,
-		ChannelID:    *topic.AnnounceChannelID,
-	}
-}

internal/store/topic_store.go

@@ -32,8 +32,6 @@ type CreateTopicInput struct {
 	DebateStartAt   time.Time
 	DebateEndAt     time.Time
 	CreatorUserID   string
-	AnnounceGuildBaseURL *string // optional; null = no broadcasts for this topic
-	AnnounceChannelID    *string
 }
 
 func (s *TopicStore) Create(ctx context.Context, in CreateTopicInput) (*models.Topic, error) {
@@ -41,11 +39,11 @@ func (s *TopicStore) Create(ctx context.Context, in CreateTopicInput) (*models.T
 	_, err := s.db.ExecContext(ctx, `
 		INSERT INTO topics (id, title, summary, visibility, verdict_schema_id,
 			signup_open_at, signup_close_at, debate_start_at, debate_end_at,
-			creator_user_id, announce_guild_base_url, announce_channel_id)
+			creator_user_id)
-		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
+		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
 		id, in.Title, in.Summary, in.Visibility, in.VerdictSchemaID,
 		in.SignupOpenAt, in.SignupCloseAt, in.DebateStartAt, in.DebateEndAt,
-		in.CreatorUserID, in.AnnounceGuildBaseURL, in.AnnounceChannelID)
+		in.CreatorUserID)
 	if err != nil {
 		return nil, fmt.Errorf("insert topic: %w", err)
 	}

main.go

@@ -19,7 +19,6 @@ import (
 
 	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/config"
 	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/db"
-	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/fabric"
 	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/httpapi"
 	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/orchestrator"
 	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/store"
@@ -51,15 +50,15 @@ func main() {
 	}
 	log.Printf("migrations: ok")
 
-	// Wire orchestrator + Fabric announcer + start the ticker.
+	// Wire orchestrator + start the ticker. Backend no longer broadcasts
-	// Per Phase 3.5: target is per-topic, only the system key stays in env.
+	// to Fabric — proposers post a single recruitment fabric-send-message,
-	announcer := fabric.NewAnnouncer(cfg.FabricSystemAPIKey)
+	// downstream agents book HF on_call slots to be woken at debate time.
 	topicStore := store.NewTopicStore(conn)
 	signupStore := store.NewSignupStore(conn)
 	campStore := store.NewCampStore(conn)
 	roundStore := store.NewRoundStore(conn)
 	ticker := orchestrator.NewTicker(conn, topicStore, signupStore, campStore, roundStore,
-		announcer, cfg.OrchestratorTickInterval)
+		cfg.OrchestratorTickInterval)
 	go ticker.Run(ctx)
 
 	srv := &http.Server{