feat: add governed chat agent selection

packages/casan-control-panel/README.md

@@ -56,7 +56,7 @@ Approval inbox / HITL:
 - `POST /api/v1/approvals/decide` — approve/reject with SoD and reason; approved
   settings proposals apply through `control-plane-settings.py`.
 
-Governed Chat (Plan-18 MVP-0/1):
+Governed Chat (Plan-18 MVP-0/1 + MVP-2 Track 4 foundation):
 
 - `POST /api/v1/chat/ask` — Ask CASAN endpoint. The API only wraps harness
   `chat-turn.py`; router verdicts, H4 input/output scan, action-gate decisions,
@@ -64,11 +64,14 @@ Governed Chat (Plan-18 MVP-0/1):
   execution remain harness-owned.
 - `GET /api/v1/chat/actions` — list registered operator actions from
   `operator-actions.yaml`; no free-command execution is exposed.
+- `GET /api/v1/chat/agents` — list governed agents from `agent-registry.yaml`
+  with role visibility; selected agent/skill/delegation are bound by harness
+  `chat-agent-resolver.py`.
 - `GET /api/v1/chat/audit/verify` — verifies the chat audit hash chain.
 - `/chat` UI shows actor/role scope, `mode/risk/decision` badges, certified answer,
-  evidence sources, registered operator actions, action-gate status, router details,
-  and audit hash. Side-effect requests outside registered actions return governed
-  `BLOCK` or `NOT_SUPPORTED` responses.
+  evidence sources, registered operator actions, agent binding, action-gate status,
+  router details, and audit hash. Side-effect requests outside registered actions
+  return governed `BLOCK` or `NOT_SUPPORTED` responses.
 
 FinOps/SLO:
 

packages/casan-control-panel/backend/src/chat/chat.controller.ts

@@ -21,4 +21,9 @@ export class ChatController {
   actions(@Headers() headers: Record<string, string | string[] | undefined>) {
     return ok(this.svc.listActions(actorFromHeaders(headers)));
   }
+
+  @Get('agents')
+  agents(@Headers() headers: Record<string, string | string[] | undefined>) {
+    return ok(this.svc.listAgents(actorFromHeaders(headers)));
+  }
 }

packages/casan-control-panel/backend/src/chat/chat.service.ts

@@ -7,6 +7,9 @@ import type { SettingsActor } from '../settings/settings.service.js';
 export interface ChatAskInput {
   message: string;
   chatId?: string;
+  agentId?: string;
+  skillId?: string;
+  delegationLevel?: number;
 }
 
 interface CommandResult {
@@ -18,6 +21,7 @@ interface CommandResult {
 const HARNESS_BIN = join(APP_ROOT, 'packages', 'casan-harness', 'scripts', 'bash');
 const CHAT_CLI = join(HARNESS_BIN, 'chat-turn.py');
 const OPERATOR_CLI = join(HARNESS_BIN, 'chat-operator.py');
+const AGENT_CLI = join(HARNESS_BIN, 'chat-agent-resolver.py');
 const RBAC_CLI = join(HARNESS_BIN, 'rbac-check.py');
 
 function runPython(script: string, args: string[]): CommandResult {
@@ -55,17 +59,25 @@ export class ChatService {
     }
     this.requireRead(actor);
 
-    const res = runPython(CHAT_CLI, [
+    const args = [
       'ask',
       '--message',
       input.message,
       '--actor',
       actor.actor,
+      '--role',
+      actor.role,
+      '--project',
+      actor.project,
       '--chat-id',
       input.chatId || 'chat-default',
       '--tenant',
       actor.tenant,
-    ]);
+    ];
+    if (input.agentId) args.push('--agent', input.agentId);
+    if (input.skillId) args.push('--skill', input.skillId);
+    if (input.delegationLevel !== undefined) args.push('--delegation-level', String(input.delegationLevel));
+    const res = runPython(CHAT_CLI, args);
     const parsed = parseJson<Record<string, any>>(res.stdout);
     if (parsed) {
       return { ...parsed, actor, audit_verify: this.verifyAudit() };
@@ -89,6 +101,14 @@ export class ChatService {
     throw new InternalServerErrorException(res.stderr || res.stdout || 'CHAT_OPERATOR_ACTIONS_FAILED');
   }
 
+  listAgents(actor: SettingsActor) {
+    this.requireRead(actor);
+    const res = runPython(AGENT_CLI, ['list-agents', '--role', actor.role]);
+    const parsed = parseJson<Record<string, any>>(res.stdout);
+    if (parsed) return parsed;
+    throw new InternalServerErrorException(res.stderr || res.stdout || 'CHAT_AGENTS_FAILED');
+  }
+
   private requireRead(actor: SettingsActor) {
     const res = runPython(RBAC_CLI, [
       'check',

packages/casan-control-panel/backend/test/chat.test.ts

@@ -6,6 +6,7 @@ import { join } from 'node:path';
 import { ChatService } from '../src/chat/chat.service.js';
 
 const viewer = { actor: 'chat-viewer', role: 'viewer', project: 'default', tenant: 'default' };
+const operator = { actor: 'chat-operator', role: 'operator', project: 'default', tenant: 'default' };
 
 function withTempChatState(fn: () => void) {
   const saved = {
@@ -66,15 +67,38 @@ test('chat ask marks side-effect requests unsupported in MVP-0', () => {
 test('chat ask executes registered operator action through action-gate', () => {
   withTempChatState(() => {
     const svc = new ChatService();
-    const actions = svc.listActions(viewer) as any;
+    const actions = svc.listActions(operator) as any;
     assert.ok(actions.actions.some((a: any) => a.id === 'run-chat-tests'));
+    const agents = svc.listAgents(operator) as any;
+    assert.ok(agents.agents.some((a: any) => a.id === 'ops-operator' && a.allowed_for_role === true));
 
-    const res = svc.ask({ message: 'run tests', chatId: 'operator-chat' }, viewer) as any;
+    const res = svc.ask({
+      message: 'run tests',
+      chatId: 'operator-chat',
+      agentId: 'ops-operator',
+      skillId: 'registered-actions',
+    }, operator) as any;
     assert.equal(res.success, true);
     assert.equal(res.mode, 'OPERATOR');
     assert.equal(res.decision, 'ACTION_COMPLETED');
     assert.equal(res.action.id, 'run-chat-tests');
     assert.equal(res.action_gate.outcome, 'ALLOW');
+    assert.equal(res.agent_binding.agent_selected, 'ops-operator');
+    assert.equal(res.agent_binding.skill_selected, 'registered-actions');
     assert.equal(res.audit_verify.ok, true);
   });
 });
+
+test('chat ask denies selected agent outside actor role', () => {
+  withTempChatState(() => {
+    const svc = new ChatService();
+    const agents = svc.listAgents(viewer) as any;
+    assert.ok(agents.agents.some((a: any) => a.id === 'ops-operator' && a.allowed_for_role === false));
+
+    const res = svc.ask({ message: 'run tests', agentId: 'ops-operator' }, viewer) as any;
+    assert.equal(res.success, false);
+    assert.equal(res.decision, 'DENIED');
+    assert.equal(res.agent_selected, 'ops-operator');
+    assert.equal(res.reason, 'role_not_allowed_for_agent');
+  });
+});

packages/casan-control-panel/frontend/src/lib/api.ts

@@ -108,6 +108,19 @@ export interface ChatAnswer {
   };
   action?: { id: string; label: string; description: string } | null;
   action_gate?: { outcome?: string; reason?: string; exit_code?: number };
+  agent_binding?: {
+    success: boolean;
+    decision: string;
+    reason: string;
+    agent_selected: string;
+    skill_selected: string;
+    delegation_level: number;
+    model_role?: string;
+    mode?: string;
+    tool_allowlist: string[];
+    requires_approval: boolean;
+    audit?: { record_hash?: string; head?: string; seq?: number };
+  };
   actor: SettingsActor;
 }
 
@@ -118,6 +131,19 @@ export interface ChatAction {
   triggers: string[];
 }
 
+export interface ChatAgent {
+  id: string;
+  label: string;
+  mode: string;
+  model_role: string;
+  roles_allowed: string[];
+  skills_allowed: string[];
+  tool_allowlist: string[];
+  max_delegation_level: number;
+  requires_approval?: boolean;
+  allowed_for_role?: boolean;
+}
+
 export interface SettingsState {
   actor: SettingsActor;
   capabilities: {
@@ -164,10 +190,11 @@ export const api = {
     post<{ proposal: any; audit_verify: { ok: boolean; output: string } }>('approvals/submit', body, actorHeaders(actor)),
   decideApproval: (actor: SettingsActor, body: { id: string; decision: 'approve' | 'reject'; reason: string }) =>
     post<{ proposal: any; applied: any; audit_verify: { ok: boolean; output: string } }>('approvals/decide', body, actorHeaders(actor)),
-  askChat: (actor: SettingsActor, body: { message: string; chatId?: string }) =>
+  askChat: (actor: SettingsActor, body: { message: string; chatId?: string; agentId?: string; skillId?: string; delegationLevel?: number }) =>
     post<ChatAnswer>('chat/ask', body, actorHeaders(actor)),
   verifyChatAudit: () => get<{ ok: boolean; output: string }>('chat/audit/verify'),
   chatActions: (actor: SettingsActor) => getWithHeaders<{ success: boolean; actions: ChatAction[] }>('chat/actions', actorHeaders(actor)),
+  chatAgents: (actor: SettingsActor) => getWithHeaders<{ success: boolean; agents: ChatAgent[] }>('chat/agents', actorHeaders(actor)),
 };
 
 // Health is raw (not enveloped) + carries HTTP status.

packages/casan-control-panel/frontend/src/pages/Chat.tsx

@@ -1,6 +1,6 @@
 import { useState } from 'react';
 import { useMutation, useQuery } from '@tanstack/react-query';
-import { api, ChatAction, ChatAnswer, SettingsActor } from '../lib/api';
+import { api, ChatAction, ChatAgent, ChatAnswer, SettingsActor } from '../lib/api';
 import { Card, StatusBadge } from '../components/ui/Card';
 
 const ROLES = ['viewer', 'auditor', 'operator', 'project-admin', 'org-admin'];
@@ -26,6 +26,9 @@ export function Chat() {
     tenant: 'default',
   });
   const [chatId, setChatId] = useState('chat-default');
+  const [agentId, setAgentId] = useState('evidence-reader');
+  const [skillId, setSkillId] = useState('evidence-summary');
+  const [delegationLevel, setDelegationLevel] = useState(0);
   const [message, setMessage] = useState('Summarize Plan 18 MVP-0 status');
   const [last, setLast] = useState<ChatAnswer | null>(null);
   const [error, setError] = useState<string | null>(null);
@@ -40,9 +43,25 @@ export function Chat() {
     queryFn: () => api.chatActions(actor),
     retry: false,
   });
+  const agentsQuery = useQuery({
+    queryKey: ['chat-agents', actor],
+    queryFn: () => api.chatAgents(actor),
+    retry: false,
+  });
+  const agents = agentsQuery.data?.agents ?? [];
+  const selectedAgent = agents.find((a) => a.id === agentId) ?? agents.find((a) => a.allowed_for_role) ?? agents[0];
+  const selectedSkill = selectedAgent?.skills_allowed.includes(skillId)
+    ? skillId
+    : (selectedAgent?.skills_allowed[0] ?? '');
 
   const ask = useMutation({
-    mutationFn: (override?: { message?: string }) => api.askChat(actor, { message: override?.message ?? message, chatId }),
+    mutationFn: (override?: { message?: string; agentId?: string; skillId?: string }) => api.askChat(actor, {
+      message: override?.message ?? message,
+      chatId,
+      agentId: override?.agentId ?? selectedAgent?.id ?? agentId,
+      skillId: override?.skillId ?? selectedSkill,
+      delegationLevel,
+    }),
     onSuccess: (res) => {
       setLast(res);
       setError(null);
@@ -111,6 +130,33 @@ export function Chat() {
               <input className="w-full rounded border border-gray-300 px-3 py-2" value={chatId}
                 onChange={(e) => setChatId(e.target.value)} />
             </label>
+            <label className="space-y-1 md:col-span-2 xl:col-span-1">
+              <span className="text-gray-500">Agent</span>
+              <select className="w-full rounded border border-gray-300 px-3 py-2" value={selectedAgent?.id ?? agentId}
+                onChange={(e) => {
+                  const next = agents.find((a) => a.id === e.target.value);
+                  setAgentId(e.target.value);
+                  setSkillId(next?.skills_allowed[0] ?? '');
+                }}>
+                {agents.map((a: ChatAgent) => (
+                  <option key={a.id} value={a.id}>
+                    {a.label}{a.allowed_for_role ? '' : ' (locked)'}
+                  </option>
+                ))}
+              </select>
+            </label>
+            <label className="space-y-1">
+              <span className="text-gray-500">Skill</span>
+              <select className="w-full rounded border border-gray-300 px-3 py-2" value={selectedSkill}
+                onChange={(e) => setSkillId(e.target.value)}>
+                {(selectedAgent?.skills_allowed ?? []).map((s) => <option key={s} value={s}>{s}</option>)}
+              </select>
+            </label>
+            <label className="space-y-1">
+              <span className="text-gray-500">Delegation</span>
+              <input className="w-full rounded border border-gray-300 px-3 py-2" type="number" min={0} max={5}
+                value={delegationLevel} onChange={(e) => setDelegationLevel(Number(e.target.value || 0))} />
+            </label>
           </div>
         </div>
       </Card>
@@ -125,6 +171,8 @@ export function Chat() {
               <StatusBadge value={last.mode} />
               <StatusBadge value={last.risk} />
               <StatusBadge value={last.decision} />
+              {last.agent_binding && <StatusBadge value={last.agent_binding.agent_selected} />}
+              {last.agent_binding && <StatusBadge value={`L${last.agent_binding.delegation_level}`} />}
               <StatusBadge value={last.audit_verify.ok ? 'audit ok' : 'audit fail'} />
             </div>
             <div className="whitespace-pre-wrap text-sm leading-6 text-gray-800">{last.answer}</div>
@@ -174,6 +222,18 @@ export function Chat() {
                   </div>
                 </div>
               )}
+              {last.agent_binding && (
+                <div className="rounded border border-gray-200 p-3">
+                  <div className="text-xs font-semibold uppercase text-gray-400">Agent binding</div>
+                  <div className="mt-1 font-medium text-gray-800">{last.agent_binding.agent_selected}</div>
+                  <div className="mt-1 text-xs text-gray-500">{last.agent_binding.skill_selected || 'no skill'}</div>
+                  <div className="mt-2 flex flex-wrap gap-2">
+                    <StatusBadge value={last.agent_binding.decision} />
+                    <StatusBadge value={last.agent_binding.model_role ?? 'model'} />
+                    <StatusBadge value={`tools ${last.agent_binding.tool_allowlist.length}`} />
+                  </div>
+                </div>
+              )}
               <div>
                 <div className="text-xs font-semibold uppercase text-gray-400">Matched rules</div>
                 <div className="mt-1 flex flex-wrap gap-2">
@@ -202,7 +262,7 @@ export function Chat() {
                 disabled={ask.isPending}
                 onClick={() => {
                   setMessage(trigger);
-                  ask.mutate({ message: trigger });
+                  ask.mutate({ message: trigger, agentId: 'ops-operator', skillId: 'registered-actions' });
                 }}
                 className="text-left rounded border border-gray-200 p-3 hover:border-blue-300 hover:bg-blue-50 disabled:opacity-50"
               >