feat: Phase F-5+F-7 — command-sync + sub-discussion + channel-create tools

Bundles the remaining "agent does things in Fabric" surface, skipping
presence-sync (Plexum's state machine isn't 1:1 with HF status semantics)
and attachments (Plexum has no media pipeline yet) — both deferred.

internal/subdisc/ (~140 LOC + 5 tests): persistent KV at
<profile>/state/plugin-kv/fabric-sub-discussions.json
- Entry: SubChannelID, HostAgentID, HostUserID, GuestUserIDs,
  HostGuide, GuestGuide, CallbackGuildNodeID, CallbackChannelID, CreatedAt
- Open / Lookup / LookupForHost (host-enforcement) / Add / Remove / All
- atomic tmp+rename persistence; corrupt file = start empty

internal/tools/tools.go — 7 new tools:
- create-chat-channel       (xType=general)
- create-work-channel       (xType=work)
- create-report-channel     (xType=report)
- create-discussion-channel (xType=discuss)
- discussion-complete       (post summary + close channel)
- create-sub-discussion     (create + invite + KV store + greeting)
- close-sub-discussion      (host-only; posts callback to parent + closes)

internal/fabric/client.go: CreateChannel / CloseChannel /
JoinChannel / LeaveChannel / SetChannelPurpose / Canvas CRUD /
SyncCommands (added in earlier F-4 commit; reused here)

cmd/plexum-fabric-channel-plugin/main.go:
- subdisc.Store opened from DefaultPath at init; passed into tools.Deps
- HostConfig adds commands_sync_key + sync_commands (defaults
  ["new","stop"]) — F-5 command-sync to every (agent,guild) pair at
  init when key is set; silently skips when omitted
- syncCommandsToGuilds: best-effort PUT per guild, logs per-guild
  outcome

scripts/install.sh: manifest tools[] expanded to 16 entries
(9 from F-4 + 7 new). create-channel variants share a schema shape.

Live verified:
  $ plexum plugin-call create-chat-channel \
      '{"agent_id":"fabrictester","guild_node_id":"test-guild2",
        "name":"plexum-f7-smoke","is_public":true}'
    → "created general channel plexum-f7-smoke (id=6315e636-...)"
  $ plexum plugin-call fabric-channel-list ...
    → 3 channels listed including the new one

F-6 (attachments) + F-5b (presence-sync) + F-8 (coalesce) deliberately
deferred — see DEV-NOTES.

Tests: 5 new in internal/subdisc (27 total in this repo).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

cmd/plexum-fabric-channel-plugin/main.go

@@ -28,6 +28,7 @@ import (
 	"git.hangman-lab.top/hzhang/Plexum-fabric-channel-plugin/internal/fabric"
 	"git.hangman-lab.top/hzhang/Plexum-fabric-channel-plugin/internal/identity"
 	"git.hangman-lab.top/hzhang/Plexum-fabric-channel-plugin/internal/inbound"
+	"git.hangman-lab.top/hzhang/Plexum-fabric-channel-plugin/internal/subdisc"
 	"git.hangman-lab.top/hzhang/Plexum-fabric-channel-plugin/internal/tokens"
 	"git.hangman-lab.top/hzhang/Plexum-fabric-channel-plugin/internal/tools"
 )
@@ -36,10 +37,14 @@ import (
 // <profile>/plugins/plexum-fabric-channel/config.json:
 //
 //	{
-//	  "center_api_base": "http://localhost:7001/api"
+//	  "center_api_base": "http://localhost:7001/api",
+//	  "commands_sync_key": "...",   // F-5: enables /command autocomplete in Fabric
+//	  "sync_commands": ["new","stop"]  // optional override; defaults to ["new","stop"]
 //	}
 type HostConfig struct {
-	CenterAPIBase string `json:"center_api_base"`
+	CenterAPIBase   string   `json:"center_api_base"`
+	CommandsSyncKey string   `json:"commands_sync_key,omitempty"`
+	SyncCommands    []string `json:"sync_commands,omitempty"`
 }
 
 type fabricPlugin struct {
@@ -155,9 +160,16 @@ func (p *fabricPlugin) Init(ctx context.Context, host plugin.HostAPI) error {
 		return p.client.AgentLogin(loginCtx, entry.FabricAPIKey)
 	})
 
+	// Sub-discussion KV (F-7); persists across restarts.
+	subStore, err := subdisc.Open(subdisc.DefaultPath())
+	if err != nil {
+		host.Log("warn", "fabric subdisc open", map[string]any{"err": err.Error()})
+	}
+
 	// Agent-facing tool surface (port of openclaw's tools.ts).
 	p.tools = tools.New(tools.Deps{
 		Client: p.client, Tokens: p.tokens, Identities: p.identities,
+		SubDisc: subStore,
 	})
 
 	host.Log("info", "fabric channel plugin initialized", map[string]any{
@@ -173,6 +185,14 @@ func (p *fabricPlugin) Init(ctx context.Context, host plugin.HostAPI) error {
 			map[string]any{"err": err.Error()})
 	}
 
+	// F-5: push slash command catalog to every guild the bound agents
+	// belong to. Cosmetic — gives Fabric frontend "/command" autocomplete.
+	// Requires commands_sync_key matching the guild's
+	// FABRIC_BACKEND_GUILD_COMMANDS_SYNC_KEY; silently skip when unset.
+	if p.cfg.CommandsSyncKey != "" {
+		p.syncCommandsToGuilds(ctx)
+	}
+
 	// Phase F-2: start the inbound supervisor in a goroutine. Lives
 	// until p.inboundCancel fires (currently never — SDK has no
 	// shutdown hook; subprocess kill is the only stop signal).
@@ -353,6 +373,47 @@ func (p *fabricPlugin) sessionFor(ctx context.Context, agentID string) (*fabric.
 	return p.tokens.Get(loginCtx, agentID)
 }
 
+// syncCommandsToGuilds PUTs the slash-command catalog to every unique
+// (agent, guild) the plugin knows about. Best-effort — failure on any
+// one guild is logged but doesn't block other guilds.
+func (p *fabricPlugin) syncCommandsToGuilds(ctx context.Context) {
+	commands := p.cfg.SyncCommands
+	if len(commands) == 0 {
+		commands = []string{"new", "stop"} // host-side intercepted slashes
+	}
+	wire := make([]any, 0, len(commands))
+	for _, c := range commands {
+		wire = append(wire, map[string]any{
+			"name": c, "description": "Plexum host-intercepted slash: /" + c,
+		})
+	}
+	seen := map[string]bool{}
+	for _, b := range p.bindings {
+		sess, err := p.tokens.Get(ctx, b.AgentID)
+		if err != nil {
+			continue
+		}
+		for _, g := range sess.Guilds {
+			key := b.AgentID + "/" + g.NodeID
+			if seen[key] {
+				continue
+			}
+			seen[key] = true
+			tok, err := p.tokens.GuildToken(ctx, b.AgentID, g.NodeID)
+			if err != nil {
+				continue
+			}
+			if err := p.client.SyncCommands(ctx, g.Endpoint, tok, wire, p.cfg.CommandsSyncKey); err != nil {
+				p.host.Log("warn", "fabric commands sync failed",
+					map[string]any{"guild": g.NodeID, "err": err.Error()})
+			} else {
+				p.host.Log("info", "fabric commands synced",
+					map[string]any{"guild": g.NodeID, "n": len(commands)})
+			}
+		}
+	}
+}
+
 func errResult(msg string) plugin.ToolResult {
 	return plugin.ToolResult{
 		Content: []plugin.ContentBlock{{Type: "text", Text: msg}},