chore: switch mergemaster to opus and add cargo fmt guidance

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.huskies/agents.toml

@@ -253,35 +253,30 @@ When the auto-resolver fails, you have access to the merge worktree at `.story_k
 6. Call the `run_tests` MCP tool to start tests, then poll `get_test_result` until complete
 7. If it compiles, commit and re-trigger merge_agent_work
 
-### Common conflict patterns in this project:
+### Common conflict patterns:
 
-**Story file rename/rename conflicts:** Both branches moved the story .md file to different pipeline directories. Resolution: `git rm` both sides — story files in `work/2_current/`, `work/3_qa/`, `work/4_merge/` are gitignored and don't need to be committed.
+**Story file rename/rename conflicts:** Both branches moved the story .md file to different pipeline directories. Resolution: `git rm` both sides — story files in pipeline directories are gitignored and don't need to be committed.
-
-**bot.rs tokio::select! conflicts:** Master has a `tokio::select!` loop in `handle_message()` that handles permission forwarding (story 275). Feature branches created before story 275 have a simpler direct `provider.chat_stream().await` call. Resolution: KEEP master's tokio::select! loop. Integrate only the feature's new logic (e.g. typing indicators, new callbacks) into the existing loop structure. Do NOT replace the loop with the old direct call.
 
 **Duplicate functions/imports:** The auto-resolver keeps both sides, producing duplicates. Resolution: keep one copy (prefer master's version), delete the duplicate.
 
 **Formatting-only conflicts:** Both sides reformatted the same code differently. Resolution: pick either side (prefer master).
 
-**IMPORTANT: After resolving ANY conflict or fixing ANY gate failure in the merge workspace, run `script/lint` (if it exists) or the project's formatter before recommitting.** The auto-resolver frequently produces code that compiles but fails formatting checks. Running the formatter after every fix prevents repeated gate failures.
+**IMPORTANT: After resolving ANY conflict or fixing ANY gate failure in the merge workspace, use the `run_lint` MCP tool to check formatting, then `run_tests` to verify everything passes before recommitting.** The auto-resolver frequently produces code that compiles but fails formatting or linting checks.
 
 ## Fixing Gate Failures
 
-If quality gates fail, attempt to fix issues yourself in the merge worktree. Use the run_tests MCP tool (then poll get_test_result) to verify — do not run script/test via Bash.
+If quality gates fail, attempt to fix issues yourself in the merge workspace. Use the run_tests MCP tool to verify before recommitting.
 
 **Fix yourself (up to 3 attempts total):**
-- Syntax errors (missing semicolons, brackets, commas)
+- Syntax errors
 - Duplicate definitions from merge artifacts
-- Simple type annotation errors
+- Unused import warnings
-- Unused import warnings flagged by clippy
+- Formatting issues that block linting
-- Mismatched braces from bad conflict resolution
-- Trivial formatting issues that block compilation or linting
 
 **Report to human without attempting a fix:**
 - Logic errors or incorrect business logic
 - Missing function implementations
 - Architectural changes required
-- Non-trivial refactoring needed
 
 **Max retry limit:** If gates still fail after 3 fix attempts, call report_merge_failure to record the failure, then stop immediately and report the full gate output to the human.
 
@@ -292,4 +287,4 @@ If quality gates fail, attempt to fix issues yourself in the merge worktree. Use
 - Report conflict resolution outcomes clearly
 - Report gate failures with full output so the human can act if needed
 - The server automatically runs acceptance gates when your process exits"""
-system_prompt = "You are the mergemaster agent. Your primary job is to merge feature branches to master. First try the merge_agent_work MCP tool. If the auto-resolver fails on complex conflicts, resolve them yourself in the merge worktree — you are an opus-class agent capable of understanding both sides of a conflict and producing correct merged code. Common patterns: keep master's tokio::select! permission loop in bot.rs, discard story file rename conflicts (gitignored), remove duplicate definitions. After resolving, verify compilation before re-triggering merge. CRITICAL: Never manually move story files or call accept_story. After 3 failed fix attempts, call report_merge_failure and stop."
+system_prompt = "You are the mergemaster agent. Your primary job is to merge feature branches to master. First try the merge_agent_work MCP tool. If the auto-resolver fails on complex conflicts, resolve them yourself in the merge workspace. Common patterns: discard story file rename conflicts (gitignored), remove duplicate definitions/imports. After resolving, verify with run_tests MCP tool before re-triggering merge. CRITICAL: Never manually move story files or call accept_story. After 3 failed fix attempts, call report_merge_failure and stop."

frontend/src/api/gateway.ts

@@ -8,6 +8,18 @@ export interface JoinedAgent {
 	label: string;
 	address: string;
 	registered_at: number;
+	/// Project this agent is assigned to, if any.
+	assigned_project?: string;
+}
+
+export interface GatewayProject {
+	name: string;
+	url: string;
+}
+
+export interface GatewayInfo {
+	active: string;
+	projects: GatewayProject[];
 }
 
 export interface GenerateTokenResponse {
@@ -61,4 +73,17 @@ export const gatewayApi = {
 			method: "DELETE",
 		});
 	},
+
+	/// Assign an agent to a project, or unassign it by passing null.
+	assignAgent(id: string, project: string | null): Promise<JoinedAgent> {
+		return gatewayRequest<JoinedAgent>(`/gateway/agents/${id}/assign`, {
+			method: "POST",
+			body: JSON.stringify({ project }),
+		});
+	},
+
+	/// Get the list of registered projects from the gateway.
+	getGatewayInfo(): Promise<GatewayInfo> {
+		return gatewayRequest<GatewayInfo>("/api/gateway");
+	},
 };

frontend/src/components/GatewayPanel.tsx

@@ -3,10 +3,10 @@
 /// Provides:
 /// - An "Add Agent" button that generates a one-time join token.
 /// - Instructions for running a build agent with the token.
-/// - A list of connected agents with per-agent "Remove" buttons.
+/// - A list of connected agents with per-agent project assignment and "Remove" buttons.
 
 import * as React from "react";
-import { gatewayApi, type JoinedAgent } from "../api/gateway";
+import { gatewayApi, type JoinedAgent, type GatewayProject } from "../api/gateway";
 
 const { useCallback, useEffect, useState } = React;
 
@@ -90,12 +90,17 @@ function TokenDisplay({ token }: { token: string }) {
 
 function AgentRow({
 	agent,
+	projects,
 	onRemove,
+	onAssign,
 }: {
 	agent: JoinedAgent;
+	projects: GatewayProject[];
 	onRemove: (id: string) => void;
+	onAssign: (id: string, project: string | null) => void;
 }) {
 	const registeredAt = new Date(agent.registered_at * 1000).toLocaleString();
+	const isAssigned = Boolean(agent.assigned_project);
 
 	return (
 		<div
@@ -116,9 +121,10 @@ function AgentRow({
 					width: "8px",
 					height: "8px",
 					borderRadius: "50%",
-					background: "#3fb950",
+					background: isAssigned ? "#3fb950" : "#6e7681",
 					flexShrink: 0,
 				}}
+				title={isAssigned ? "Assigned" : "Idle (unassigned)"}
 			/>
 			<div style={{ flex: 1 }}>
 				<div style={{ fontWeight: 600, color: "#e6edf3" }}>{agent.label}</div>
@@ -129,6 +135,29 @@ function AgentRow({
 					Registered {registeredAt}
 				</div>
 			</div>
+			<select
+				data-testid={`assign-agent-${agent.id}`}
+				value={agent.assigned_project ?? ""}
+				onChange={(e) =>
+					onAssign(agent.id, e.target.value === "" ? null : e.target.value)
+				}
+				style={{
+					fontSize: "0.8em",
+					padding: "4px 8px",
+					borderRadius: "4px",
+					border: "1px solid #30363d",
+					background: "#0d1117",
+					color: "#e6edf3",
+					cursor: "pointer",
+				}}
+			>
+				<option value="">— unassigned —</option>
+				{projects.map((p) => (
+					<option key={p.name} value={p.name}>
+						{p.name}
+					</option>
+				))}
+			</select>
 			<button
 				type="button"
 				data-testid={`remove-agent-${agent.id}`}
@@ -152,6 +181,7 @@ function AgentRow({
 /// Gateway management panel — rendered when running in `--gateway` mode.
 export function GatewayPanel() {
 	const [agents, setAgents] = useState<JoinedAgent[]>([]);
+	const [projects, setProjects] = useState<GatewayProject[]>([]);
 	const [token, setToken] = useState<string | null>(null);
 	const [generating, setGenerating] = useState(false);
 	const [error, setError] = useState<string | null>(null);
@@ -161,6 +191,10 @@ export function GatewayPanel() {
 			.listAgents()
 			.then(setAgents)
 			.catch(() => setAgents([]));
+		gatewayApi
+			.getGatewayInfo()
+			.then((info) => setProjects(info.projects))
+			.catch(() => setProjects([]));
 	}, []);
 
 	const handleAddAgent = useCallback(async () => {
@@ -186,6 +220,20 @@ export function GatewayPanel() {
 		}
 	}, []);
 
+	const handleAssignAgent = useCallback(
+		async (id: string, project: string | null) => {
+			try {
+				const updated = await gatewayApi.assignAgent(id, project);
+				setAgents((prev) =>
+					prev.map((a) => (a.id === updated.id ? updated : a)),
+				);
+			} catch (e) {
+				setError(e instanceof Error ? e.message : String(e));
+			}
+		},
+		[],
+	);
+
 	return (
 		<div
 			style={{
@@ -273,7 +321,9 @@ export function GatewayPanel() {
 								<AgentRow
 									key={agent.id}
 									agent={agent}
+									projects={projects}
 									onRemove={handleRemoveAgent}
+									onAssign={handleAssignAgent}
 								/>
 							))}
 						</div>

server/src/gateway.rs

@@ -17,7 +17,7 @@ use serde::{Deserialize, Serialize};
 use serde_json::{Value, json};
 use std::collections::BTreeMap;
 use std::collections::HashMap;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 use std::sync::Arc;
 use tokio::sync::RwLock;
 use uuid::Uuid;
@@ -64,6 +64,9 @@ pub struct JoinedAgent {
     pub address: String,
     /// Unix timestamp when the agent registered.
     pub registered_at: f64,
+    /// Project this agent is assigned to, if any.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub assigned_project: Option<String>,
 }
 
 /// A one-time join token that has been generated but not yet consumed.
@@ -80,6 +83,14 @@ struct RegisterAgentRequest {
     address: String,
 }
 
+/// Request body for assigning or reassigning an agent to a project.
+///
+/// Send `{"project": "my-project"}` to assign, or `{"project": null}` to unassign.
+#[derive(Deserialize)]
+struct AssignAgentRequest {
+    project: Option<String>,
+}
+
 // ── Gateway state ────────────────────────────────────────────────────
 
 /// Shared gateway state threaded through HTTP handlers.
@@ -95,22 +106,51 @@ pub struct GatewayState {
     pub joined_agents: Arc<RwLock<Vec<JoinedAgent>>>,
     /// One-time join tokens that have been issued but not yet consumed.
     pending_tokens: Arc<RwLock<HashMap<String, PendingToken>>>,
+    /// Directory containing `projects.toml`, used for persisting agent data.
+    pub config_dir: PathBuf,
+}
+
+/// Load persisted agents from `<config_dir>/gateway_agents.json`.
+/// Returns an empty list if the file does not exist or cannot be parsed.
+fn load_agents(config_dir: &Path) -> Vec<JoinedAgent> {
+    let path = config_dir.join("gateway_agents.json");
+    match std::fs::read(&path) {
+        Ok(data) => serde_json::from_slice(&data).unwrap_or_default(),
+        Err(_) => Vec::new(),
+    }
+}
+
+/// Persist the current agent list to `<config_dir>/gateway_agents.json`.
+/// Silently ignores write errors (e.g. read-only filesystem or empty path).
+async fn save_agents(agents: &[JoinedAgent], config_dir: &Path) {
+    if config_dir == Path::new("") {
+        return;
+    }
+    let path = config_dir.join("gateway_agents.json");
+    if let Ok(data) = serde_json::to_vec_pretty(agents) {
+        let _ = tokio::fs::write(&path, data).await;
+    }
 }
 
 impl GatewayState {
-    /// Create a new gateway state from a config. The first project in the config
+    /// Create a new gateway state from a config and config directory.
-    /// becomes the active project by default.
+    ///
-    pub fn new(config: GatewayConfig) -> Result<Self, String> {
+    /// The first project in the config becomes the active project by default.
+    /// Previously registered agents are loaded from `gateway_agents.json` in
+    /// `config_dir` if the file exists.
+    pub fn new(config: GatewayConfig, config_dir: PathBuf) -> Result<Self, String> {
         if config.projects.is_empty() {
             return Err("projects.toml must define at least one project".to_string());
         }
         let first = config.projects.keys().next().unwrap().clone();
+        let agents = load_agents(&config_dir);
         Ok(Self {
             config,
             active_project: Arc::new(RwLock::new(first)),
             client: Client::new(),
-            joined_agents: Arc::new(RwLock::new(Vec::new())),
+            joined_agents: Arc::new(RwLock::new(agents)),
             pending_tokens: Arc::new(RwLock::new(HashMap::new())),
+            config_dir,
         })
     }
 
@@ -622,6 +662,7 @@ pub async fn gateway_register_agent_handler(
         label: req.label,
         address: req.address,
         registered_at: chrono::Utc::now().timestamp() as f64,
+        assigned_project: None,
     };
 
     crate::slog!(
@@ -630,7 +671,11 @@ pub async fn gateway_register_agent_handler(
         agent.id
     );
 
-    state.joined_agents.write().await.push(agent.clone());
+    {
+        let mut agents = state.joined_agents.write().await;
+        agents.push(agent.clone());
+        save_agents(&agents, &state.config_dir).await;
+    }
 
     let body = serde_json::to_vec(&agent).unwrap_or_default();
     Response::builder()
@@ -656,11 +701,16 @@ pub async fn gateway_remove_agent_handler(
     PoemPath(id): PoemPath<String>,
     state: Data<&Arc<GatewayState>>,
 ) -> Response {
-    let mut agents = state.joined_agents.write().await;
+    let removed = {
-    let before = agents.len();
+        let mut agents = state.joined_agents.write().await;
-    agents.retain(|a| a.id != id);
+        let before = agents.len();
-    let removed = agents.len() < before;
+        agents.retain(|a| a.id != id);
-    drop(agents);
+        let removed = agents.len() < before;
+        if removed {
+            save_agents(&agents, &state.config_dir).await;
+        }
+        removed
+    };
 
     if removed {
         crate::slog!("[gateway] Removed agent id={id}");
@@ -674,6 +724,63 @@ pub async fn gateway_remove_agent_handler(
     }
 }
 
+/// `POST /gateway/agents/:id/assign` — assign or unassign an agent to a project.
+///
+/// Body: `{ "project": "my-project" }` to assign, or `{ "project": null }` to unassign.
+/// Returns the updated `JoinedAgent` on success. The assignment is persisted to disk
+/// so it survives gateway restarts.
+#[handler]
+pub async fn gateway_assign_agent_handler(
+    PoemPath(id): PoemPath<String>,
+    body: Json<AssignAgentRequest>,
+    state: Data<&Arc<GatewayState>>,
+) -> Response {
+    let project = body
+        .0
+        .project
+        .and_then(|p| if p.is_empty() { None } else { Some(p) });
+
+    if let Some(ref p) = project
+        && !state.config.projects.contains_key(p.as_str())
+    {
+        return Response::builder()
+            .status(StatusCode::BAD_REQUEST)
+            .body(Body::from(format!("unknown project '{p}'")));
+    }
+
+    let updated = {
+        let mut agents = state.joined_agents.write().await;
+        match agents.iter_mut().find(|a| a.id == id) {
+            None => None,
+            Some(a) => {
+                a.assigned_project = project;
+                Some(a.clone())
+            }
+        }
+    };
+
+    match updated {
+        None => Response::builder()
+            .status(StatusCode::NOT_FOUND)
+            .body(Body::from("agent not found")),
+        Some(agent) => {
+            crate::slog!(
+                "[gateway] Agent '{}' (id={}) assigned to {:?}",
+                agent.label,
+                agent.id,
+                agent.assigned_project
+            );
+            let agents = state.joined_agents.read().await.clone();
+            save_agents(&agents, &state.config_dir).await;
+            let body = serde_json::to_vec(&agent).unwrap_or_default();
+            Response::builder()
+                .status(StatusCode::OK)
+                .header("Content-Type", "application/json")
+                .body(Body::from(body))
+        }
+    }
+}
+
 // ── Health aggregation endpoint ──────────────────────────────────────
 
 /// HTTP GET `/health` handler for the gateway — aggregates health from all projects.
@@ -948,8 +1055,14 @@ pub async fn gateway_switch_handler(
 
 /// Start the gateway HTTP server. This is the entry point when `--gateway` is used.
 pub async fn run(config_path: &Path, port: u16) -> Result<(), std::io::Error> {
+    // Locate the gateway config directory (parent of `projects.toml`).
+    let config_dir = config_path
+        .parent()
+        .unwrap_or(std::path::Path::new("."))
+        .to_path_buf();
+
     let config = GatewayConfig::load(config_path).map_err(std::io::Error::other)?;
-    let state = GatewayState::new(config).map_err(std::io::Error::other)?;
+    let state = GatewayState::new(config, config_dir.clone()).map_err(std::io::Error::other)?;
     let state_arc = Arc::new(state);
 
     let active = state_arc.active_project.read().await.clone();
@@ -965,12 +1078,6 @@ pub async fn run(config_path: &Path, port: u16) -> Result<(), std::io::Error> {
             .join(", ")
     );
 
-    // Locate the gateway config directory (parent of `projects.toml`).
-    let config_dir = config_path
-        .parent()
-        .unwrap_or(std::path::Path::new("."))
-        .to_path_buf();
-
     // Write `.mcp.json` so that the gateway's Matrix bot's Claude Code CLI
     // connects to this gateway's MCP endpoint (which proxies to the active project).
     if let Err(e) = write_gateway_mcp_json(&config_dir, port) {
@@ -1010,6 +1117,10 @@ pub async fn run(config_path: &Path, port: u16) -> Result<(), std::io::Error> {
             "/gateway/agents/:id",
             poem::delete(gateway_remove_agent_handler),
         )
+        .at(
+            "/gateway/agents/:id/assign",
+            poem::post(gateway_assign_agent_handler),
+        )
         // Serve the embedded React frontend so the gateway has a UI.
         .at(
             "/assets/*path",
@@ -1127,7 +1238,7 @@ url = "http://localhost:3002"
         let config = GatewayConfig {
             projects: BTreeMap::new(),
         };
-        assert!(GatewayState::new(config).is_err());
+        assert!(GatewayState::new(config, PathBuf::new()).is_err());
     }
 
     #[test]
@@ -1146,7 +1257,7 @@ url = "http://localhost:3002"
             },
         );
         let config = GatewayConfig { projects };
-        let state = GatewayState::new(config).unwrap();
+        let state = GatewayState::new(config, PathBuf::new()).unwrap();
         let active = state.active_project.blocking_read().clone();
         assert_eq!(active, "alpha"); // BTreeMap sorts alphabetically.
     }
@@ -1179,7 +1290,7 @@ url = "http://localhost:3002"
             },
         );
         let config = GatewayConfig { projects };
-        let state = GatewayState::new(config).unwrap();
+        let state = GatewayState::new(config, PathBuf::new()).unwrap();
 
         let params = json!({ "arguments": { "project": "beta" } });
         let resp = handle_switch_project(&params, &state).await;
@@ -1199,7 +1310,7 @@ url = "http://localhost:3002"
             },
         );
         let config = GatewayConfig { projects };
-        let state = GatewayState::new(config).unwrap();
+        let state = GatewayState::new(config, PathBuf::new()).unwrap();
 
         let params = json!({ "arguments": { "project": "nonexistent" } });
         let resp = handle_switch_project(&params, &state).await;
@@ -1216,7 +1327,7 @@ url = "http://localhost:3002"
             },
         );
         let config = GatewayConfig { projects };
-        let state = GatewayState::new(config).unwrap();
+        let state = GatewayState::new(config, PathBuf::new()).unwrap();
 
         let url = state.active_url().await.unwrap();
         assert_eq!(url, "http://my:3001");
@@ -1352,7 +1463,7 @@ enabled = false
             },
         );
         let config = GatewayConfig { projects };
-        Arc::new(GatewayState::new(config).unwrap())
+        Arc::new(GatewayState::new(config, PathBuf::new()).unwrap())
     }
 
     #[tokio::test]
@@ -1452,6 +1563,7 @@ enabled = false
             label: "agent-1".into(),
             address: "ws://a:3001/crdt-sync".into(),
             registered_at: 0.0,
+            assigned_project: None,
         });
         let app = poem::Route::new()
             .at("/gateway/agents", poem::get(gateway_list_agents_handler))
@@ -1472,6 +1584,7 @@ enabled = false
             label: "to-delete".into(),
             address: "ws://x:3001/crdt-sync".into(),
             registered_at: 0.0,
+            assigned_project: None,
         });
         let app = poem::Route::new()
             .at(