feat: multi-session webhook claim system with EADDRINUSE handling

- Server gracefully handles EADDRINUSE (logs notice, continues without server)
- POST /claim endpoint with referral-based async handoff:
  202 (pending) -> poll with referral_id -> 200/401/408
- GET /claim shows current owner and pending queue
- DOS protection: 503 when MAX_PENDING_CLAIMS (10) reached
- Claims expire after 5 minutes
- Pi commands: /webhook:status, /webhook:claim, /webhook:release

pi-extension/index.ts

@@ -3,6 +3,7 @@
  *
  * Registers Gitea tools (read + write) and optional webhook server.
  * Supports @mention routing for multi-bot coordination.
+ * Supports multi-session claim system for webhook ownership.
  */
 
 import registerReadTools from "./tools/read-tools.js";
@@ -11,6 +12,8 @@ import {
 	startWebhookServer, stopWebhookServer,
 	startPolling, stopPolling,
 	setSendMessage, getTrackedRepos, setRepoConfig,
+	setOnClaimRequested, approvePendingClaim, getClaimStatus,
+	SESSION_ID, WEBHOOK_PORT, WEBHOOK_HOST,
 } from "./webhook/server.js";
 import type { ExtensionAPI } from "@mariozechner/pi-coding-agent";
 import { Type } from "@sinclair/typebox";
@@ -42,7 +45,7 @@ export default function (pi: ExtensionAPI) {
 			}
 			const config = setRepoConfig(params.repo, { respondTo: mode });
 			return {
-				content: [{ type: "text", text: `✅ ${params.repo}: respondTo = ${config.respondTo}` }],
+				content: [{ type: "text", text: `${params.repo}: respondTo = ${config.respondTo}` }],
 				details: { repo: params.repo, config },
 			};
 		},
@@ -59,11 +62,11 @@ export default function (pi: ExtensionAPI) {
 
 			for (const [name] of webhook) {
 				const mode = configs.get(name)?.respondTo ?? "all";
-				lines.push(`✅ ${name} — webhook (respondTo: ${mode})`);
+				lines.push(`${name} — webhook (respondTo: ${mode})`);
 			}
 			for (const name of collab) {
 				const mode = configs.get(name)?.respondTo ?? "mention";
-				lines.push(`📋 ${name} — collab/notification (respondTo: ${mode})`);
+				lines.push(`${name} — collab/notification (respondTo: ${mode})`);
 			}
 
 			return {
@@ -73,6 +76,157 @@ export default function (pi: ExtensionAPI) {
 		},
 	});
 
+	// ── Webhook claim commands ───────────────────────────────────────────────
+
+	pi.registerCommand("webhook:status", {
+		description: "Show webhook server status and claim ownership",
+		handler: async (_args, _ctx) => {
+			const status = getClaimStatus();
+
+			if (status.isOwner && status.pending.length === 0) {
+				console.log(`Webhook: you own the server (session: ${status.sessionId})`);
+				console.log(`  port: ${WEBHOOK_PORT}, cwd: ${status.ownerCwd}`);
+			} else if (status.isOwner) {
+				console.log(`Webhook: you own the server (session: ${status.sessionId})`);
+				console.log(`  port: ${WEBHOOK_PORT}, cwd: ${status.ownerCwd}`);
+				console.log(`  ${status.pending.length} pending claim(s):`);
+				for (const c of status.pending) {
+					const age = Math.round((Date.now() - c.createdAt) / 1000);
+					console.log(`    ${c.referralId} from ${c.sessionId} (${c.cwd}) — ${age}s ago`);
+				}
+				console.log(`  Use /webhook:release to hand off to next in queue`);
+			} else {
+				// Not the server owner — query the server
+				try {
+					const res = await fetch(`http://127.0.0.1:${WEBHOOK_PORT}/claim`);
+					if (res.ok) {
+						const data = await res.json() as Record<string, unknown>;
+						console.log(`Webhook: owned by another session`);
+						console.log(`  owner: ${data.owner} (cwd: ${data.owner_cwd})`);
+						console.log(`  server session: ${data.server_session}`);
+						const pending = data.pending as Array<Record<string, unknown>>;
+						if (pending?.length) {
+							console.log(`  ${pending.length} pending claim(s)`);
+						}
+						console.log(`  Use /webhook:claim to request ownership`);
+					} else {
+						console.log(`Webhook: no server running on port ${WEBHOOK_PORT}`);
+					}
+				} catch {
+					console.log(`Webhook: no server reachable on port ${WEBHOOK_PORT}`);
+				}
+			}
+		},
+	});
+
+	pi.registerCommand("webhook:claim", {
+		description: "Request webhook ownership from the current server owner",
+		handler: async (_args, ctx) => {
+			const status = getClaimStatus();
+
+			if (status.isOwner) {
+				console.log("You already own the webhook server.");
+				return;
+			}
+
+			// POST to the running server's /claim endpoint
+			const url = `http://127.0.0.1:${WEBHOOK_PORT}/claim`;
+			let referralId: string | undefined;
+
+			try {
+				// Initial request
+				const initRes = await fetch(url, {
+					method: "POST",
+					headers: { "Content-Type": "application/json" },
+					body: JSON.stringify({ session_id: SESSION_ID, cwd: process.cwd() }),
+				});
+
+				if (initRes.status === 503) {
+					console.log("Server has too many pending claims. Try again later.");
+					return;
+				}
+
+				const initData = await initRes.json() as Record<string, unknown>;
+
+				if (initRes.status === 200) {
+					console.log("Claimed immediately (no contention).");
+					return;
+				}
+
+				if (initRes.status !== 202) {
+					console.log(`Unexpected response: ${initRes.status} ${JSON.stringify(initData)}`);
+					return;
+				}
+
+				referralId = initData.referral_id as string;
+				console.log(`Claim submitted (referral: ${referralId})`);
+				console.log(`  Current owner: ${initData.owner} (${initData.owner_cwd})`);
+				console.log(`  Queue position: ${initData.position}`);
+				console.log(`  Waiting for owner to /webhook:release ...`);
+
+				// Poll every 3s for up to 5 minutes
+				const deadline = Date.now() + 5 * 60 * 1000;
+				while (Date.now() < deadline) {
+					await new Promise((r) => setTimeout(r, 3000));
+
+					const pollRes = await fetch(url, {
+						method: "POST",
+						headers: { "Content-Type": "application/json" },
+						body: JSON.stringify({ session_id: SESSION_ID, referral_id: referralId }),
+					});
+
+					if (pollRes.status === 200) {
+						console.log("Claim approved — you now own the webhook server.");
+						return;
+					}
+					if (pollRes.status === 401) {
+						console.log("Claim denied by the current owner.");
+						return;
+					}
+					if (pollRes.status === 408) {
+						console.log("Claim expired (timed out).");
+						return;
+					}
+					// 202 = still pending, continue polling
+				}
+
+				console.log("Claim timed out (client-side deadline).");
+			} catch (err) {
+				const msg = err instanceof Error ? err.message : String(err);
+				if (msg.includes("ECONNREFUSED")) {
+					console.log(`No webhook server running on port ${WEBHOOK_PORT}.`);
+				} else {
+					console.log(`Claim failed: ${msg}`);
+				}
+			}
+		},
+	});
+
+	pi.registerCommand("webhook:release", {
+		description: "Release webhook ownership to the next pending claimer",
+		handler: async (_args, _ctx) => {
+			const status = getClaimStatus();
+
+			if (!status.isOwner) {
+				console.log("You don't own the webhook server — nothing to release.");
+				return;
+			}
+
+			if (status.pending.length === 0) {
+				console.log("No pending claims to hand off to.");
+				return;
+			}
+
+			const { approved, newOwner } = approvePendingClaim();
+			if (approved) {
+				console.log(`Ownership transferred to ${approved.sessionId} (${approved.cwd})`);
+				console.log(`New owner session: ${newOwner}`);
+			} else {
+				console.log("No pending claims (they may have expired).");
+			}
+		},
+	});
+
 	// ── Lifecycle ────────────────────────────────────────────────────────────
 
 	// GITEA_ENABLE_POLLING=1 opts in to running the webhook server + notification poller.
@@ -82,7 +236,13 @@ export default function (pi: ExtensionAPI) {
 		(!process.env.GITEA_HOOKS_URL && !process.env.OPENCLAW_HOOKS_URL);
 
 	pi.on("session_start", async (_event, ctx) => {
-		console.log("[pi-gitea] Session started");
+		console.log(`[pi-gitea] Session started (session: ${SESSION_ID})`);
+
+		// Set up claim notification — alert the user when another session wants ownership
+		setOnClaimRequested((claim) => {
+			console.log(`[pi-gitea] Claim request from ${claim.sessionId} (${claim.cwd})`);
+			console.log(`[pi-gitea] Use /webhook:release to hand off, or ignore to let it expire`);
+		});
 
 		// Auto-detect runtime: pi-bot (persistent session) vs openclaw (hooks endpoint)
 		if (ctx.sendUserMessage) {
@@ -115,12 +275,8 @@ export default function (pi: ExtensionAPI) {
 		}
 
 		if (enablePolling) {
-			try {
 			await startWebhookServer(pi);
 			await startPolling(pi);
-			} catch (err) {
-				console.error("[pi-gitea] Failed to start webhook/polling:", err);
-			}
 		} else {
 			console.log("[pi-gitea] Webhook server + polling disabled (openclaw mode — tools only)");
 		}

pi-extension/webhook/server.ts

@@ -32,6 +32,7 @@ const STATE_FILE = "/home/pibot/.pi/agent/gitea-poll-state.json";
 // ── State ────────────────────────────────────────────────────────────────────
 
 let server: Server | null = null;
+let serverOwned = false; // true if THIS process bound the port
 let processingQueue: Array<{ prompt: string; timestamp: number }> = [];
 const maxQueueDepth = 50;
 let isProcessing = false;
@@ -39,6 +40,189 @@ let repoPollTimer: NodeJS.Timeout | null = null;
 let notifPollTimer: NodeJS.Timeout | null = null;
 let sendMessage: ((message: string) => Promise<void>) | null = null;
 
+// ── Claim system ─────────────────────────────────────────────────────────────
+// Multiple pi sessions may start concurrently. Only one can bind the webhook
+// port.  The instance that binds it becomes the initial "claim owner" — webhook
+// events are delivered to its sendMessage callback.
+//
+// Other sessions can request ownership via POST /claim:
+//
+//   1. Client sends POST /claim { session_id, cwd, referral_id? }
+//   2. Server responds 202 { referral_id, position, owner }    — queued
+//   3. Client polls   POST /claim { session_id, referral_id }
+//   4. Server responds:
+//        202 — still pending (current owner hasn't released)
+//        200 — claimed (you are the new owner)
+//        401 — denied (owner explicitly rejected — reserved for future use)
+//        408 — timed out (claim expired)
+//   5. GET /claim — returns current owner info + pending queue
+//
+// The current owner releases via the /webhook:release pi command, which calls
+// approvePendingClaim() in-process (no HTTP needed — it's the server process).
+//
+// DOS protection: max pending referrals; 503 for new clients when full.
+
+/** Unique id for this pi process */
+const SESSION_ID = `pi-${process.pid}-${Date.now().toString(36)}`;
+
+/** Session id of whoever currently receives events */
+let claimOwner: string = SESSION_ID;
+/** CWD of current owner (for display) */
+let claimOwnerCwd: string = process.cwd();
+
+interface ClaimRequest {
+	referralId: string;
+	sessionId: string;
+	cwd: string;
+	status: "pending" | "approved" | "denied" | "expired";
+	createdAt: number;
+}
+
+const MAX_PENDING_CLAIMS = 10;
+const CLAIM_TIMEOUT_MS = 5 * 60 * 1000; // 5 minutes
+let pendingClaims: Map<string, ClaimRequest> = new Map();
+
+/** Notify callback — set by the extension to alert the current owner */
+let onClaimRequested: ((claim: ClaimRequest) => void) | null = null;
+
+export function setOnClaimRequested(fn: (claim: ClaimRequest) => void) {
+	onClaimRequested = fn;
+}
+
+function generateReferralId(): string {
+	return `ref-${Date.now().toString(36)}-${Math.random().toString(36).slice(2, 8)}`;
+}
+
+function purgeExpiredClaims() {
+	const now = Date.now();
+	for (const [id, claim] of pendingClaims) {
+		if (now - claim.createdAt > CLAIM_TIMEOUT_MS) {
+			claim.status = "expired";
+			pendingClaims.delete(id);
+		}
+	}
+}
+
+/**
+ * Called by the server owner (via /webhook:release command) to approve the
+ * next pending claim.  Transfers ownership to the oldest pending request.
+ */
+export function approvePendingClaim(): { approved: ClaimRequest | null; newOwner: string } {
+	purgeExpiredClaims();
+
+	// Find oldest pending
+	let oldest: ClaimRequest | null = null;
+	for (const claim of pendingClaims.values()) {
+		if (claim.status === "pending") {
+			if (!oldest || claim.createdAt < oldest.createdAt) {
+				oldest = claim;
+			}
+		}
+	}
+
+	if (!oldest) {
+		return { approved: null, newOwner: claimOwner };
+	}
+
+	oldest.status = "approved";
+	claimOwner = oldest.sessionId;
+	claimOwnerCwd = oldest.cwd;
+	console.log(`[gitea-claim] Ownership transferred to ${oldest.sessionId} (${oldest.cwd})`);
+
+	return { approved: oldest, newOwner: claimOwner };
+}
+
+/** Get current claim status for display */
+export function getClaimStatus() {
+	purgeExpiredClaims();
+	return {
+		owner: claimOwner,
+		ownerCwd: claimOwnerCwd,
+		sessionId: SESSION_ID,
+		isOwner: claimOwner === SESSION_ID,
+		pending: [...pendingClaims.values()].filter((c) => c.status === "pending"),
+	};
+}
+
+/** Handle POST /claim from another pi instance */
+function handleClaimRequest(body: { session_id?: string; cwd?: string; referral_id?: string }): {
+	status: number;
+	body: Record<string, unknown>;
+} {
+	purgeExpiredClaims();
+
+	const sessionId = body.session_id ?? "unknown";
+	const cwd = body.cwd ?? "unknown";
+	const referralId = body.referral_id;
+
+	// Polling with existing referral
+	if (referralId) {
+		const claim = pendingClaims.get(referralId);
+		if (!claim) {
+			// Unknown referral — expired or never existed
+			return { status: 408, body: { error: "expired", referral_id: referralId } };
+		}
+		if (claim.status === "approved") {
+			pendingClaims.delete(referralId);
+			return {
+				status: 200,
+				body: { claimed: true, referral_id: referralId, owner: claimOwner },
+			};
+		}
+		if (claim.status === "denied") {
+			pendingClaims.delete(referralId);
+			return { status: 401, body: { denied: true, referral_id: referralId } };
+		}
+		if (claim.status === "expired") {
+			pendingClaims.delete(referralId);
+			return { status: 408, body: { error: "expired", referral_id: referralId } };
+		}
+		// Still pending
+		const position = [...pendingClaims.values()]
+			.filter((c) => c.status === "pending" && c.createdAt <= claim.createdAt)
+			.length;
+		return {
+			status: 202,
+			body: {
+				referral_id: referralId,
+				status: "pending",
+				position,
+				owner: claimOwner,
+				owner_cwd: claimOwnerCwd,
+			},
+		};
+	}
+
+	// New claim request (no referral_id)
+	if (pendingClaims.size >= MAX_PENDING_CLAIMS) {
+		return { status: 503, body: { error: "too many pending claims" } };
+	}
+
+	const newReferralId = generateReferralId();
+	const claim: ClaimRequest = {
+		referralId: newReferralId,
+		sessionId,
+		cwd,
+		status: "pending",
+		createdAt: Date.now(),
+	};
+	pendingClaims.set(newReferralId, claim);
+
+	console.log(`[gitea-claim] New claim request from ${sessionId} (${cwd}), referral: ${newReferralId}`);
+	if (onClaimRequested) onClaimRequested(claim);
+
+	return {
+		status: 202,
+		body: {
+			referral_id: newReferralId,
+			status: "pending",
+			position: pendingClaims.size,
+			owner: claimOwner,
+			owner_cwd: claimOwnerCwd,
+		},
+	};
+}
+
 /** Repos where we successfully installed a webhook */
 let webhookRepos: Map<string, { webhookId: number; addedAt: number }> = new Map();
 
@@ -302,7 +486,7 @@ function validateToken(req: IncomingMessage): boolean {
 }
 
 export function startWebhookServer(_pi: ExtensionAPI) {
-	return new Promise<void>(async (resolve, reject) => {
+	return new Promise<void>(async (resolve) => {
 		try {
 			const http = await import("node:http");
 
@@ -326,6 +510,9 @@ export function startWebhookServer(_pi: ExtensionAPI) {
 						status: "ok",
 						uptime: process.uptime(),
 						bot_user: BOT_USER,
+						session_id: SESSION_ID,
+						claim_owner: claimOwner,
+						claim_owner_cwd: claimOwnerCwd,
 						webhook_repos: webhookRepos.size,
 						collab_repos: collabRepos.size,
 						queue_depth: processingQueue.length,
@@ -334,6 +521,46 @@ export function startWebhookServer(_pi: ExtensionAPI) {
 					return;
 				}
 
+				// GET /claim — current owner info
+				if (url === "/claim" && req.method === "GET") {
+					purgeExpiredClaims();
+					res.writeHead(200, { "Content-Type": "application/json" });
+					res.end(JSON.stringify({
+						owner: claimOwner,
+						owner_cwd: claimOwnerCwd,
+						server_session: SESSION_ID,
+						pending: [...pendingClaims.values()]
+							.filter((c) => c.status === "pending")
+							.map((c) => ({
+								referral_id: c.referralId,
+								session_id: c.sessionId,
+								cwd: c.cwd,
+								age_ms: Date.now() - c.createdAt,
+							})),
+					}));
+					return;
+				}
+
+				// POST /claim — request or poll claim
+				if (url === "/claim" && req.method === "POST") {
+					let rawBody = "";
+					for await (const chunk of req) rawBody += chunk.toString();
+
+					let reqBody: any;
+					try {
+						reqBody = JSON.parse(rawBody);
+					} catch {
+						res.writeHead(400, { "Content-Type": "application/json" });
+						res.end(JSON.stringify({ error: "Invalid JSON" }));
+						return;
+					}
+
+					const result = handleClaimRequest(reqBody);
+					res.writeHead(result.status, { "Content-Type": "application/json" });
+					res.end(JSON.stringify(result.body));
+					return;
+				}
+
 				// POST /hooks/gitea
 				if (url === "/hooks/gitea" && req.method === "POST") {
 					if (!validateToken(req)) {
@@ -366,13 +593,28 @@ export function startWebhookServer(_pi: ExtensionAPI) {
 			});
 
 			server.listen(WEBHOOK_PORT, WEBHOOK_HOST, () => {
-				console.log(`[gitea-webhook] Server listening on ${WEBHOOK_HOST}:${WEBHOOK_PORT}`);
+				serverOwned = true;
+				claimOwner = SESSION_ID;
+				claimOwnerCwd = process.cwd();
+				console.log(`[gitea-webhook] Server listening on ${WEBHOOK_HOST}:${WEBHOOK_PORT} (session: ${SESSION_ID})`);
 				resolve();
 			});
 
-			server.on("error", reject);
+			server.on("error", (err: NodeJS.ErrnoException) => {
+				if (err.code === "EADDRINUSE") {
+					server = null;
+					serverOwned = false;
+					console.log(`[gitea-webhook] Port ${WEBHOOK_PORT} already in use — another pi instance owns the webhook server`);
+					console.log(`[gitea-webhook] Use /webhook:claim to request ownership, or /webhook:status to see current owner`);
+					resolve(); // not fatal — tools still work, just no local server
+				} else {
+					console.error(`[gitea-webhook] Server error: ${err.message}`);
+					resolve(); // don't crash the extension
+				}
+			});
 		} catch (err) {
-			reject(err);
+			console.error(`[gitea-webhook] Failed to create server: ${err}`);
+			resolve();
 		}
 	});
 }
@@ -695,4 +937,4 @@ export function setRepoConfig(repo: string, config: Partial<RepoConfig>): RepoCo
 	return updated;
 }
 
-export { parseMentions, type MentionInfo, type RepoConfig };
+export { parseMentions, type MentionInfo, type RepoConfig, type ClaimRequest, SESSION_ID, WEBHOOK_PORT, WEBHOOK_HOST };