fix(provenance): address #143 re-review — shared resolver + decoupled badge

Architecture & design:
- Arch A: introduce resolveProvenance() as the single source of truth for
  deriving a write's actor/aiChatId from the SIGNED identity, and wire it into
  BOTH transport seams — the REST jwt.strategy and the collab
  authentication.extension. Previously the collab seam derived actor from the
  token claim alone and ignored user.isAgent, so a flagged service account's
  page-content edits over the websocket persisted as lastUpdatedSource='user',
  drifting from REST. The seams now share one resolver and can't diverge.
- Arch B: drop AiAgentBadge's page-history coupling. The generic ui/ badge no
  longer imports historyAtoms; it exposes an onActivate callback fired after the
  deep-link, and the history row passes onActivate to close its own modal.

Suggestions/warnings:
- S1: soften the jwt.strategy provenance comment (applies to every REST write).
- S2/suggestion-3: drop the redundant comment-list-item null-aiChatId test
  (covered by ai-agent-badge.test.tsx).
- S3: de-duplicate jwt.strategy.spec test #3 (the no-claim→'user' half
  duplicated test #2); keep only the signed actor='agent' claim assertion.
- W2: add keyboard-activation tests for the badge (Enter/Space, unrelated key).
- W3: flip the design doc status to "реализовано (#143)".

Tests:
- new auth-provenance.decorator.spec.ts unit-tests resolveProvenance +
  agentSourceFields.
- new collab-seam test: is_agent user with no claim → actor='agent'
  (Arch A regression guard).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

apps/server/src/core/auth/strategies/jwt.strategy.spec.ts

@@ -77,31 +77,20 @@ describe('JwtStrategy — provenance derivation', () => {
     expect(req.raw.aiChatId).toBeNull();
   });
 
-  it("does NOT let an 'actor' claim escalate a non-agent user beyond the existing claim semantics", async () => {
-    // A non-agent user. The only way the token carries actor='agent' is the
-    // internal AI-chat's server-minted token (the claim cannot be set by a
-    // client on a plain login). We assert the derivation falls back to the
-    // claim ONLY when is_agent is false — i.e. an is_agent=false user is never
-    // forced to 'agent' by anything other than that signed claim, and a plain
-    // user (no claim) stays 'user'.
+  it("honors a SIGNED actor='agent' claim on a non-agent user's token (the internal AI-chat path)", async () => {
+    // A non-agent user (the plain no-claim → 'user' case is covered above). A
+    // token that DOES carry actor='agent' resolves to 'agent' — BY DESIGN: that
+    // claim can only exist on a SERVER-MINTED provenance token (the internal AI
+    // chat), never on a plain login token, because the token is signed with the
+    // app secret. The guarantee is that a client cannot FORGE this signed claim,
+    // not that the strategy ignores it. (A plain user still cannot obtain
+    // 'agent' — they have no way to get such a token.)
     const { strategy } = makeStrategy({
       id: 'user-1',
       isAgent: false,
       deactivatedAt: null,
       deletedAt: null,
     });
-    const req = makeReq();
-
-    // No actor claim (the plain-user login case): stays 'user'.
-    await strategy.validate(req, accessPayload() as any);
-    expect(req.raw.actor).toBe('user');
-
-    // A token that DOES carry actor='agent' resolves to 'agent' — BY DESIGN:
-    // that claim can only exist on a SERVER-MINTED provenance token (the internal
-    // AI chat), never on a plain login token, because the token is signed with
-    // the app secret. The security guarantee is that a client cannot forge this
-    // signed claim, NOT that the strategy ignores it. (A plain user therefore
-    // still cannot obtain 'agent' — they have no way to get such a token.)
     const req2 = makeReq();
     await strategy.validate(req2, accessPayload({ actor: 'agent', aiChatId: 'chat-1' }) as any);
     expect(req2.raw.actor).toBe('agent');

apps/server/src/core/auth/strategies/jwt.strategy.ts

@@ -10,6 +10,7 @@ import { SessionActivityService } from '../../session/session-activity.service';
 import { FastifyRequest } from 'fastify';
 import { extractBearerTokenFromHeader, isUserDisabled } from '../../../common/helpers';
 import { ModuleRef } from '@nestjs/core';
+import { resolveProvenance } from '../../../common/decorators/auth-provenance.decorator';
 
 @Injectable()
 export class JwtStrategy extends PassportStrategy(Strategy, 'jwt') {
@@ -72,18 +73,14 @@ export class JwtStrategy extends PassportStrategy(Strategy, 'jwt') {
     }
 
     // Propagate the agent-edit provenance onto the request so REST
-    // services/controllers can set the 'agent' marker off it. Provenance is
-    // derived from the SIGNED server-side identity, never from a client body
-    // field, so a normal user cannot fake an 'agent' badge:
-    //  - An account flagged is_agent (an MCP service account) stamps EVERY write
-    //    as 'agent'. It has no internal ai_chats row, so aiChatId stays null.
-    //  - Otherwise fall back to the actor claim minted into the internal AI
-    //    agent's token (actor='agent' + aiChatId); a normal user token carries
-    //    no claim and resolves to 'user' (unchanged behaviour).
-    req.raw.actor = user.isAgent
-      ? 'agent'
-      : ((payload as JwtPayload).actor ?? 'user');
-    req.raw.aiChatId = (payload as JwtPayload).aiChatId ?? null;
+    // services/controllers can set the 'agent' marker off it. Derived from the
+    // SIGNED server-side identity via the shared resolver (also used by the
+    // collab seam, so the two never drift), never from a client body field — so
+    // an is_agent service account stamps every REST write made with an access
+    // token, and a normal user cannot fake an 'agent' badge.
+    const provenance = resolveProvenance(user, payload as JwtPayload);
+    req.raw.actor = provenance.actor;
+    req.raw.aiChatId = provenance.aiChatId;
 
     return { user, workspace };
   }