feat(maint): session-status endpoint for agent picker

Unlock Agent / Force Ready shortcuts used to read the target agentId from localStorage helix_agent_config — supervisors don't have that set and got 400 'agentId required'.

- SessionService.listLockedSessions() — SCAN over agent:session:*
- POST /api/maint/session-status returns { locked, free } by joining
  the platform Agent entities against Redis session locks
- orphan locks (Redis key with no matching Agent record) surface in
  the Locked bucket so the operator can still clear stale lock state

src/maint/maint.controller.ts

@@ -56,6 +56,59 @@ export class MaintController {
         }
     }
 
+    // Returns the current per-agent session state — which ozonetelAgentIds
+    // are currently locked (held by a member IP) and which are free. Used
+    // by the maint OTP modal to render a picker so a supervisor can unlock
+    // the right agent without knowing the id off the top of their head.
+    // Read-only; OTP-guarded like the rest of /api/maint.
+    @Post('session-status')
+    async sessionStatus() {
+        const data = await this.platform.query<any>(
+            `{ agents(first: 100) { edges { node { id name ozonetelAgentId ozonetelDisplayName } } } }`,
+        ).catch(() => ({ agents: { edges: [] } }));
+
+        const allAgents = (data?.agents?.edges ?? []).map((e: any) => e.node).filter((a: any) => a.ozonetelAgentId);
+        const sessions = await this.session.listLockedSessions();
+        const sessionByAgent = new Map(sessions.map((s) => [s.agentId.toLowerCase(), s]));
+
+        const locked: Array<any> = [];
+        const free: Array<any> = [];
+        const seenAgentIds = new Set<string>();
+
+        for (const agent of allAgents) {
+            const key = String(agent.ozonetelAgentId).toLowerCase();
+            seenAgentIds.add(key);
+            const session = sessionByAgent.get(key);
+            const row = {
+                agentId: agent.ozonetelAgentId,
+                displayName: agent.name ?? agent.ozonetelDisplayName ?? agent.ozonetelAgentId,
+            };
+            if (session) {
+                locked.push({ ...row, heldByIp: session.ip, lockedAt: session.lockedAt });
+            } else {
+                free.push(row);
+            }
+        }
+
+        // Surface orphan locks (Redis holds a session for an ozonetelAgentId
+        // with no matching Agent entity). Rare but possible after SDK renames
+        // or workspace resets — without surfacing them, the operator can't
+        // clear the stale lock via the UI.
+        for (const session of sessions) {
+            const key = session.agentId.toLowerCase();
+            if (!seenAgentIds.has(key)) {
+                locked.push({
+                    agentId: session.agentId,
+                    displayName: `${session.agentId} (orphan — no Agent record)`,
+                    heldByIp: session.ip,
+                    lockedAt: session.lockedAt,
+                });
+            }
+        }
+
+        return { locked, free };
+    }
+
     @Post('unlock-agent')
     async unlockAgent(@Body() body: { agentId: string }) {
         if (!body?.agentId) throw new HttpException('agentId required', 400);