diff --git a/apps/api/e2e/tracker.e2e-spec.ts b/apps/api/e2e/tracker.e2e-spec.ts
index 056c1fd..8c90e1f 100644
--- a/apps/api/e2e/tracker.e2e-spec.ts
+++ b/apps/api/e2e/tracker.e2e-spec.ts
@@ -1755,4 +1755,101 @@ describe('task-stream (e2e)', () => {
       (await rest('token-ana', 'PUT', `/issues/${id}/presence`, {})).body,
     ).toEqual([]);
   });
+
+  it('lets a guest see and talk about only their own tickets', async () => {
+    const key = 'G' + Date.now().toString(36).slice(-5).toUpperCase();
+    await rest('token-ana', 'POST', '/projects', { key, name: key });
+    await eventually(
+      () => rest('token-ana', 'GET', `/projects/${key}`),
+      (r) => r.status === 200,
+    );
+    // Quinn, a client, joins as a guest.
+    expect((await rest('token-qa', 'GET', '/users/me')).status).toBe(200);
+    expect(
+      (
+        await rest('token-ana', 'POST', `/projects/${key}/members`, {
+          userId: '103',
+          role: 'GUEST',
+        })
+      ).status,
+    ).toBe(201);
+    await eventually(
+      () => rest('token-qa', 'GET', `/projects/${key}`),
+      (r) => r.status === 200,
+    );
+    const internal = (
+      await rest('token-ana', 'POST', `/projects/${key}/issues`, {
+        type: 'TASK',
+        title: 'Solo del equipo',
+      })
+    ).body['key'];
+
+    // A guest opens a ticket, but does not plan it.
+    expect(
+      (
+        await rest('token-qa', 'POST', `/projects/${key}/issues`, {
+          type: 'BUG',
+          title: 'Con asignación',
+          assigneeId: '101',
+        })
+      ).status,
+    ).toBe(403);
+    const mine = (
+      await rest('token-qa', 'POST', `/projects/${key}/issues`, {
+        type: 'BUG',
+        title: 'No puedo pagar',
+      })
+    ).body['key'];
+    await eventually(
+      () => rest('token-qa', 'GET', `/issues/${mine}`),
+      (r) => r.status === 200,
+    );
+
+    const list = await eventually(
+      () => rest('token-ana', 'GET', `/projects/${key}/issues`),
+      (r) => r.body?.['total'] === 2,
+    );
+    expect(list.body['total']).toBe(2);
+    const guestList = await rest('token-qa', 'GET', `/projects/${key}/issues`);
+    expect(guestList.body['items'].map((i: { key: string }) => i.key)).toEqual([
+      mine,
+    ]);
+    expect((await rest('token-qa', 'GET', `/issues/${internal}`)).status).toBe(
+      404,
+    );
+    expect(
+      (await rest('token-qa', 'PUT', `/issues/${internal}/watch`)).status,
+    ).toBe(404);
+    // Project-wide views are not theirs.
+    expect(
+      (await rest('token-qa', 'GET', `/projects/${key}/activity`)).status,
+    ).toBe(403);
+    expect(
+      (await rest('token-qa', 'GET', `/projects/${key}/stats`)).status,
+    ).toBe(403);
+
+    // They talk on their ticket, but do not move it.
+    expect(
+      (
+        await rest('token-qa', 'POST', `/issues/${mine}/comments`, {
+          body: '¿Hay novedades?',
+        })
+      ).status,
+    ).toBe(201);
+    expect(
+      (
+        await rest('token-qa', 'PUT', `/issues/${mine}/status`, {
+          status: 'TODO',
+        })
+      ).status,
+    ).toBe(403);
+    // Once the team adds them to a ticket, they see it.
+    await rest('token-ana', 'PUT', `/issues/${internal}/assignee`, {
+      assigneeId: '103',
+    });
+    await eventually(
+      () => rest('token-qa', 'GET', `/issues/${internal}`),
+      (r) => r.status === 200,
+    );
+  });
 });
diff --git a/apps/api/openapi.json b/apps/api/openapi.json
index a0e7656..2e35072 100644
--- a/apps/api/openapi.json
+++ b/apps/api/openapi.json
@@ -11060,7 +11060,8 @@
           "OWNER",
           "ADMIN",
           "MEMBER",
-          "VIEWER"
+          "VIEWER",
+          "GUEST"
         ]
       },
       "ProjectMemberDto": {
diff --git a/apps/api/schema.gql b/apps/api/schema.gql
index ccc372e..a2b17a4 100644
--- a/apps/api/schema.gql
+++ b/apps/api/schema.gql
@@ -1213,6 +1213,7 @@ input ProjectMemberInput {
 
 enum ProjectRole {
   ADMIN
+  GUEST
   MEMBER
   OWNER
   VIEWER
diff --git a/apps/mcp/src/app/api/taskstream.schema.ts b/apps/mcp/src/app/api/taskstream.schema.ts
index 66bfed5..1572893 100644
--- a/apps/mcp/src/app/api/taskstream.schema.ts
+++ b/apps/mcp/src/app/api/taskstream.schema.ts
@@ -1721,7 +1721,7 @@ export interface components {
             name: string;
         };
         /** @enum {string} */
-        ProjectRole: "OWNER" | "ADMIN" | "MEMBER" | "VIEWER";
+        ProjectRole: "OWNER" | "ADMIN" | "MEMBER" | "VIEWER" | "GUEST";
         ProjectMemberDto: {
             user: components["schemas"]["UserRefDto"];
             role: components["schemas"]["ProjectRole"];
diff --git a/docs/03-api.md b/docs/03-api.md
index c53240b..f03ad7d 100644
--- a/docs/03-api.md
+++ b/docs/03-api.md
@@ -38,12 +38,20 @@ classDiagram
 
 ### Roles por proyecto
 
-| Rol                              | Ver | Crear/modificar tickets, comentar | Gestionar miembros y releases                |
-| -------------------------------- | --- | --------------------------------- | -------------------------------------------- |
-| `OWNER` (quien crea el proyecto) | ✅  | ✅                                | ✅ (no se le puede quitar ni cambiar el rol) |
-| `ADMIN`                          | ✅  | ✅                                | ✅                                           |
-| `MEMBER`                         | ✅  | ✅                                | ❌                                           |
-| `VIEWER`                         | ✅  | ❌                                | ❌                                           |
+| Rol                              | Ver              | Crear/modificar tickets, comentar               | Gestionar miembros y releases                |
+| -------------------------------- | ---------------- | ----------------------------------------------- | -------------------------------------------- |
+| `OWNER` (quien crea el proyecto) | ✅               | ✅                                              | ✅ (no se le puede quitar ni cambiar el rol) |
+| `ADMIN`                          | ✅               | ✅                                              | ✅                                           |
+| `MEMBER`                         | ✅               | ✅                                              | ❌                                           |
+| `VIEWER`                         | ✅               | ❌                                              | ❌                                           |
+| `GUEST`                          | Solo sus tickets | Abrir tickets, comentar y adjuntar en los suyos | ❌                                           |
+
+Un **invitado** (`GUEST`, para clientes o gente de fuera) de un proyecto privado solo ve los tickets en los que
+participa: los que abrió, los que tiene asignados y los que sigue. El resto no existen para él (`404`, también en
+«Mi trabajo», en las suscripciones en tiempo real, en «bloqueado por» y en los enlazados), y las vistas de todo el
+proyecto (actividad, estadísticas, panel, releases, sprints, épicas, papelera) le responden `403`. Abre tickets sin
+asignarlos ni planificarlos, comenta y adjunta en los suyos; no cambia su estado ni sus campos. En un proyecto público
+ve lo mismo que cualquiera.
 
 Cualquiera puede salir de un proyecto (salvo el propietario). Los no miembros reciben _not found_, para no revelar que
 el proyecto existe.
diff --git a/docs/04-cliente-web.md b/docs/04-cliente-web.md
index b9a60fa..3296d35 100644
--- a/docs/04-cliente-web.md
+++ b/docs/04-cliente-web.md
@@ -296,7 +296,7 @@ visualización de la plataforma:
 | `/p/:key/analytics`        | Estadísticas: creados vs. resueltos, flujo acumulado, burnup de una release, tiempos de ciclo y entrega, QA y resueltos por persona (30 días a 1 año)                                                                                                                                                                                                                                                                                                                                                                                                              |
 | `/p/:key/settings`         | Configuración (propietario y admins; pestaña oculta para el resto): estados (orden, categoría, color, motivo), transiciones, tipos, áreas, equipos (con sus miembros), definición de «Hecho» y campos personalizados; archivar en lugar de borrar                                                                                                                                                                                                                                                                                                                  |
 | `/p/:key/activity`         | Actividad en vivo                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
-| `/p/:key/members`          | Miembros                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
+| `/p/:key/members`          | Miembros, con su rol (propietario, admin, miembro, lector o invitado). Un invitado de un proyecto privado solo tiene Tablero, Lista y Miembros, ve solo sus tickets y abre tickets sin asignarlos ni planificarlos                                                                                                                                                                                                                                                                                                                                                 |
 
 Solo `/` está protegida por `authGuard` (redirige a `/login?returnUrl=…`); `/login` y `/auth/callback` son para quien
 no tiene sesión, y el resto se puede abrir sin ella si el proyecto es público. Los parámetros de ruta llegan como inputs de
diff --git a/docs/10-futuro.md b/docs/10-futuro.md
index 9f35165..1ee3c79 100644
--- a/docs/10-futuro.md
+++ b/docs/10-futuro.md
@@ -39,7 +39,6 @@ Nada: la tanda está hecha (ver 10.5).
   vista.
 - **Entornos de despliegue**: en qué entorno está cada ticket (pruebas, producción), desde los avisos de la
   integración continua.
-- **Rol «invitado»**: solo ve los tickets en los que participa (clientes, externos).
 - **Página pública de novedades**: las notas de versión publicadas en una página por proyecto, con RSS.
 - **Vista de cartera**: progreso de épicas y releases de todos los proyectos en una página.
 
@@ -121,3 +120,5 @@ Mucho trabajo para lo que aportan hoy; se pueden recuperar si alguien los necesi
 - Equipos dentro del proyecto: grupos de miembros en Configuración; los tickets se asignan a uno, la lista filtra por
   equipo y «@equipo» avisa a todos sus miembros.
 - Presencia: en cada ticket se ve quién más lo está viendo o editando en ese momento.
+- Rol «invitado»: para clientes o gente de fuera; en un proyecto privado solo ve los tickets en los que participa,
+  abre tickets y comenta en los suyos.
diff --git a/docs/TaskStream-Documentacion.docx b/docs/TaskStream-Documentacion.docx
index cecba35..c563615 100644
Binary files a/docs/TaskStream-Documentacion.docx and b/docs/TaskStream-Documentacion.docx differ
diff --git a/docs/TaskStream-Documentacion.pdf b/docs/TaskStream-Documentacion.pdf
index 507ae63..07ac1c4 100644
Binary files a/docs/TaskStream-Documentacion.pdf and b/docs/TaskStream-Documentacion.pdf differ
diff --git a/libs/api/tracker/application/src/lib/blockers.service.spec.ts b/libs/api/tracker/application/src/lib/blockers.service.spec.ts
index 791dc1a..bf2a5dd 100644
--- a/libs/api/tracker/application/src/lib/blockers.service.spec.ts
+++ b/libs/api/tracker/application/src/lib/blockers.service.spec.ts
@@ -3,6 +3,7 @@ import {
   IssueReadModel,
   StatusCategory,
 } from '@task-stream/api/tracker/domain';
+import { ReadAccess } from './queries/read-access';
 import { BlockersService } from './blockers.service';
 import { FindIssuesRepository } from './ports/find-issues.repository';
 
@@ -30,12 +31,15 @@ describe('BlockersService', () => {
     ].map((i) => [i.id, i]),
   );
   const queries: string[][] = [];
-  const service = new BlockersService({
-    findByIds: async (ids: string[]) => {
-      queries.push(ids);
-      return ids.map((id) => store.get(id)).filter(Boolean);
-    },
-  } as unknown as FindIssuesRepository);
+  const service = new BlockersService(
+    {
+      findByIds: async (ids: string[]) => {
+        queries.push(ids);
+        return ids.map((id) => store.get(id)).filter(Boolean);
+      },
+    } as unknown as FindIssuesRepository,
+    { participantScope: async () => null } as unknown as ReadAccess,
+  );
   const link = (
     type: IssueLinkType,
     direction: 'INWARD' | 'OUTWARD',
diff --git a/libs/api/tracker/application/src/lib/blockers.service.ts b/libs/api/tracker/application/src/lib/blockers.service.ts
index 0bf3253..b19bf3f 100644
--- a/libs/api/tracker/application/src/lib/blockers.service.ts
+++ b/libs/api/tracker/application/src/lib/blockers.service.ts
@@ -1,3 +1,4 @@
+import { involves, ReadAccess } from './queries/read-access';
 import { Injectable } from '@nestjs/common';
 import {
   IssueLinkType,
@@ -31,19 +32,28 @@ export class BlockersService {
     result: Promise<Map<string, IssueReadModel>>;
   } | null = null;
 
-  constructor(private readonly findIssues: FindIssuesRepository) {}
+  constructor(
+    private readonly findIssues: FindIssuesRepository,
+    private readonly access: ReadAccess,
+  ) {}
 
-  async blockedBy(issue: IssueReadModel): Promise<Blocker[]> {
+  /** For `viewerId`: a guest only learns of blockers they take part in. */
+  async blockedBy(
+    issue: IssueReadModel,
+    viewerId: string | null = null,
+  ): Promise<Blocker[]> {
     const ids = blockerIdsOf(issue);
     if (!ids.length) return [];
     const found = await this.load(ids);
+    const scope = await this.access.participantScope(issue.projectId, viewerId);
     return ids
       .map((id) => found.get(id))
       .filter(
         (blocker): blocker is IssueReadModel =>
           !!blocker &&
           !blocker.trashedAt &&
-          !FINISHED.has(blocker.statusCategory),
+          !FINISHED.has(blocker.statusCategory) &&
+          (!scope || involves(blocker, scope)),
       )
       .map(({ id, key, title }) => ({ id, key, title }));
   }
diff --git a/libs/api/tracker/application/src/lib/calendar/calendar.ts b/libs/api/tracker/application/src/lib/calendar/calendar.ts
index b000274..4c4619d 100644
--- a/libs/api/tracker/application/src/lib/calendar/calendar.ts
+++ b/libs/api/tracker/application/src/lib/calendar/calendar.ts
@@ -1,3 +1,4 @@
+import { guestOnly } from '../queries/read-access';
 import { randomBytes } from 'node:crypto';
 import {
   Command,
@@ -120,10 +121,14 @@ export class GetCalendarIcsQueryHandler
     const projects = await this.findProjects.findByMember(feed.userId);
     const byId = new Map(projects.map((p) => [p.id, p]));
     const ids = projects.map((p) => p.id);
+    // A guest's calendar has their tickets, not the project's plans.
+    const planned = projects
+      .filter((p) => !guestOnly(p, feed.userId))
+      .map((p) => p.id);
     const [issues, sprints, releases, me] = await Promise.all([
       this.findIssues.findDatedFor(feed.userId, ids),
-      Promise.all(ids.map((id) => this.findSprints.findByProject(id))),
-      Promise.all(ids.map((id) => this.findReleases.findByProject(id))),
+      Promise.all(planned.map((id) => this.findSprints.findByProject(id))),
+      Promise.all(planned.map((id) => this.findReleases.findByProject(id))),
       this.users.findById(feed.userId),
     ]);
     const link = linkTo(query.webUrl);
diff --git a/libs/api/tracker/application/src/lib/changes.service.ts b/libs/api/tracker/application/src/lib/changes.service.ts
index 1e6b995..a671260 100644
--- a/libs/api/tracker/application/src/lib/changes.service.ts
+++ b/libs/api/tracker/application/src/lib/changes.service.ts
@@ -12,6 +12,17 @@ import {
 } from './ports/change-feed';
 import { CanViewProjectQuery } from './queries/can-view-project.query';
 import { GetIssueQuery } from './queries/get-issue.query';
+import { GetTicketScopeQuery } from './queries/get-ticket-scope.query';
+import { involves } from './queries/read-access';
+
+/** The changes of the tickets `userId` opened, has or follows. */
+async function* onlyInvolving(
+  changes: AsyncIterableIterator<IssueChange>,
+  userId: string,
+): AsyncIterableIterator<IssueChange> {
+  for await (const change of changes)
+    if (involves(change.issue, userId)) yield change;
+}
 
 /** Realtime subscriptions, authorised at subscribe time. */
 @Injectable()
@@ -26,7 +37,12 @@ export class ChangesService {
     projectId: string,
   ): Promise<AsyncIterableIterator<IssueChange>> {
     await this.assertCanView(viewerId, projectId);
-    return this.changeFeed.issues(projectId);
+    const changes = this.changeFeed.issues(projectId);
+    const scope: string | null = await this.queryBus.execute(
+      new GetTicketScopeQuery(viewerId, projectId),
+    );
+    // A guest hears only about the tickets they take part in.
+    return scope ? onlyInvolving(changes, scope) : changes;
   }
 
   async watchComments(
@@ -41,7 +57,7 @@ export class ChangesService {
     viewerId: string,
     projectId: string,
   ): Promise<AsyncIterableIterator<ActivityReadModel>> {
-    await this.assertCanView(viewerId, projectId);
+    await this.assertCanView(viewerId, projectId, true);
     return this.changeFeed.activity(projectId);
   }
 
@@ -49,7 +65,7 @@ export class ChangesService {
     viewerId: string,
     projectId: string,
   ): Promise<AsyncIterableIterator<ReleaseChange>> {
-    await this.assertCanView(viewerId, projectId);
+    await this.assertCanView(viewerId, projectId, true);
     return this.changeFeed.releases(projectId);
   }
 
@@ -57,7 +73,7 @@ export class ChangesService {
     viewerId: string,
     projectId: string,
   ): Promise<AsyncIterableIterator<SprintChange>> {
-    await this.assertCanView(viewerId, projectId);
+    await this.assertCanView(viewerId, projectId, true);
     return this.changeFeed.sprints(projectId);
   }
 
@@ -77,9 +93,10 @@ export class ChangesService {
   private async assertCanView(
     viewerId: string,
     projectId: string,
+    wholeProject = false,
   ): Promise<void> {
     const allowed = await this.queryBus.execute(
-      new CanViewProjectQuery(viewerId, projectId),
+      new CanViewProjectQuery(viewerId, projectId, wholeProject),
     );
     if (!allowed) throw new NotFoundError('Project', projectId);
   }
diff --git a/libs/api/tracker/application/src/lib/commands/add-comment.command-handler.ts b/libs/api/tracker/application/src/lib/commands/add-comment.command-handler.ts
index a04fb39..25155ef 100644
--- a/libs/api/tracker/application/src/lib/commands/add-comment.command-handler.ts
+++ b/libs/api/tracker/application/src/lib/commands/add-comment.command-handler.ts
@@ -16,7 +16,7 @@ export class AddCommentCommandHandler
   ) {}
 
   async execute(command: AddCommentCommand): Promise<CommandResult> {
-    const { issue } = await this.access.issueForContributor(
+    const { issue } = await this.access.issueForReporter(
       command.issueId,
       command.actorId,
     );
diff --git a/libs/api/tracker/application/src/lib/commands/attach-file.command-handler.ts b/libs/api/tracker/application/src/lib/commands/attach-file.command-handler.ts
index 31d9fdd..c338ad5 100644
--- a/libs/api/tracker/application/src/lib/commands/attach-file.command-handler.ts
+++ b/libs/api/tracker/application/src/lib/commands/attach-file.command-handler.ts
@@ -20,7 +20,7 @@ export class AttachFileCommandHandler
   ) {}
 
   async execute(command: AttachFileCommand): Promise<AttachmentResult> {
-    const { issue } = await this.access.issueForContributor(
+    const { issue } = await this.access.issueForReporter(
       command.issueId,
       command.actorId,
     );
diff --git a/libs/api/tracker/application/src/lib/commands/create-issue.command-handler.ts b/libs/api/tracker/application/src/lib/commands/create-issue.command-handler.ts
index 45f57b5..2c55ec9 100644
--- a/libs/api/tracker/application/src/lib/commands/create-issue.command-handler.ts
+++ b/libs/api/tracker/application/src/lib/commands/create-issue.command-handler.ts
@@ -1,7 +1,9 @@
 import { randomUUID } from 'node:crypto';
 import { CommandHandler, EventPublisher, ICommandHandler } from '@nestjs/cqrs';
+import { ForbiddenError } from '@task-stream/api/shared/domain';
 import {
   IssueFactory,
+  ProjectRole,
   SYSTEM_ACTOR_ID,
   assertCanNest,
 } from '@task-stream/api/tracker/domain';
@@ -27,8 +29,21 @@ export class CreateIssueCommandHandler
     const project = await this.access.project(command.projectId);
     // TaskStream itself (proposals from the public form) is no member; only
     // internal commands act as it, never a request from outside.
-    if (command.actorId !== SYSTEM_ACTOR_ID)
-      project.assertCanContribute(command.actorId);
+    if (command.actorId !== SYSTEM_ACTOR_ID) {
+      project.assertCanReport(command.actorId);
+      // A guest opens a ticket; planning it is for the team.
+      if (
+        project.roleOf(command.actorId) === ProjectRole.GUEST &&
+        (command.assigneeId ||
+          command.releaseId ||
+          command.parentId ||
+          command.initialStatus ||
+          command.details.team)
+      )
+        throw new ForbiddenError(
+          'Un invitado abre el ticket; asignarlo, planificarlo o colgarlo de otro lo hace el equipo',
+        );
+    }
     // Before taking a number: an invalid type or area must not burn one.
     const workflow = project.workflow;
     workflow.assertActiveType(command.type);
diff --git a/libs/api/tracker/application/src/lib/commands/react-to-comment.command-handler.ts b/libs/api/tracker/application/src/lib/commands/react-to-comment.command-handler.ts
index c2becf9..29b54f4 100644
--- a/libs/api/tracker/application/src/lib/commands/react-to-comment.command-handler.ts
+++ b/libs/api/tracker/application/src/lib/commands/react-to-comment.command-handler.ts
@@ -18,6 +18,11 @@ export class ReactToCommentCommandHandler
       throw new ForbiddenError(
         `You are not a member of project ${project.key}`,
       );
+    this.access.assertSees(
+      project,
+      await this.access.issue(comment.issueId),
+      command.actorId,
+    );
     comment.react(command.actorId, command.emoji, command.on);
     await comment.commitAndWait();
     return ack(comment);
diff --git a/libs/api/tracker/application/src/lib/commands/vote-issue.command-handler.ts b/libs/api/tracker/application/src/lib/commands/vote-issue.command-handler.ts
index 7d83fa9..64e4661 100644
--- a/libs/api/tracker/application/src/lib/commands/vote-issue.command-handler.ts
+++ b/libs/api/tracker/application/src/lib/commands/vote-issue.command-handler.ts
@@ -25,6 +25,7 @@ export class VoteIssueCommandHandler
         `You are not a member of project ${project.key}`,
       );
     project.assertNotArchived();
+    this.access.assertSees(project, issue, command.actorId);
     if (issue.trashedAt)
       throw new BusinessRuleError(`${issue.key} is in the trash`);
     issue.vote(command.actorId, command.on);
diff --git a/libs/api/tracker/application/src/lib/commands/watch-issue.command-handler.ts b/libs/api/tracker/application/src/lib/commands/watch-issue.command-handler.ts
index 2e5710e..9fc353d 100644
--- a/libs/api/tracker/application/src/lib/commands/watch-issue.command-handler.ts
+++ b/libs/api/tracker/application/src/lib/commands/watch-issue.command-handler.ts
@@ -25,6 +25,8 @@ export class WatchIssueCommandHandler
         `You are not a member of project ${project.key}`,
       );
     }
+    // Following would show a guest a ticket they are not part of.
+    this.access.assertSees(project, issue, command.userId);
     if (command.watching) issue.watch(command.actorId, command.userId);
     else issue.unwatch(command.actorId, command.userId);
     await issue.commitAndWait();
diff --git a/libs/api/tracker/application/src/lib/commands/write-access.ts b/libs/api/tracker/application/src/lib/commands/write-access.ts
index 43902c9..316571e 100644
--- a/libs/api/tracker/application/src/lib/commands/write-access.ts
+++ b/libs/api/tracker/application/src/lib/commands/write-access.ts
@@ -74,6 +74,31 @@ export class WriteAccess {
     return { issue, project };
   }
 
+  /**
+   * Issue + its project, for opening a conversation on it (comments, files,
+   * following): members and the guests who take part in the ticket.
+   */
+  async issueForReporter(
+    issueId: string,
+    actorId: string,
+  ): Promise<{ issue: Issue; project: Project }> {
+    const issue = await this.issue(issueId);
+    const project = await this.project(issue.projectId);
+    project.assertCanReport(actorId);
+    this.assertSees(project, issue, actorId);
+    if (issue.trashedAt)
+      throw new BusinessRuleError(
+        `${issue.key} is in the trash: restore it to change it`,
+      );
+    return { issue, project };
+  }
+
+  /** A guest knows no ticket they do not take part in. */
+  assertSees(project: Project, issue: Issue, userId: string): void {
+    if (project.seesOnlyOwnTickets(userId) && !issue.involves(userId))
+      throw new NotFoundError('Issue', issue.key);
+  }
+
   /** Release of the same project that still accepts tickets. */
   async openReleaseOf(project: Project, releaseId: string): Promise<Release> {
     const release = await this.release(releaseId);
diff --git a/libs/api/tracker/application/src/lib/event-handlers/activity-summary.ts b/libs/api/tracker/application/src/lib/event-handlers/activity-summary.ts
index af5382e..bc78b73 100644
--- a/libs/api/tracker/application/src/lib/event-handlers/activity-summary.ts
+++ b/libs/api/tracker/application/src/lib/event-handlers/activity-summary.ts
@@ -79,6 +79,7 @@ const ROLE: Record<ProjectRole, string> = {
   [ProjectRole.ADMIN]: 'admin',
   [ProjectRole.MEMBER]: 'miembro',
   [ProjectRole.VIEWER]: 'lector',
+  [ProjectRole.GUEST]: 'invitado',
 };
 
 const FIELD: Record<string, string> = {
diff --git a/libs/api/tracker/application/src/lib/ports/find-issues.repository.ts b/libs/api/tracker/application/src/lib/ports/find-issues.repository.ts
index 55153a3..927d68c 100644
--- a/libs/api/tracker/application/src/lib/ports/find-issues.repository.ts
+++ b/libs/api/tracker/application/src/lib/ports/find-issues.repository.ts
@@ -47,6 +47,8 @@ export interface IssueFilter {
   watching?: boolean;
   /** Only the ones this person follows. */
   watcherId?: string;
+  /** Only the ones this person opened, has or follows (a guest's view). */
+  participantId?: string;
   /** RECENT (default): last updated first. RANK: backlog order. */
   sort?: IssueSort;
   search?: string;
@@ -63,6 +65,9 @@ export interface CrossProjectIssueFilter {
   statuses?: string[];
   categories?: StatusCategory[];
   priorities?: IssuePriority[];
+  /** Of these, only the tickets `participantId` opened, has or follows. */
+  guestProjectIds?: string[];
+  participantId?: string;
   /** Project id → the only type ids taken there. */
   typesByProject?: Record<string, string[]>;
   /** Due before this day (`YYYY-MM-DD`, excluded). */
diff --git a/libs/api/tracker/application/src/lib/presence.service.spec.ts b/libs/api/tracker/application/src/lib/presence.service.spec.ts
index fa701a9..0595100 100644
--- a/libs/api/tracker/application/src/lib/presence.service.spec.ts
+++ b/libs/api/tracker/application/src/lib/presence.service.spec.ts
@@ -29,9 +29,8 @@ const issues = {
       : null,
 } as unknown as FindIssuesRepository;
 const access = {
-  assertCanView: async (_projectId: string, viewerId: string) => {
+  assertCanViewIssue: async (_issue: IssueReadModel, viewerId: string) => {
     if (viewerId === 'eve') throw new ForbiddenError('No');
-    return 'MEMBER';
   },
 } as unknown as ReadAccess;
 
diff --git a/libs/api/tracker/application/src/lib/presence.service.ts b/libs/api/tracker/application/src/lib/presence.service.ts
index fec11a6..64ae21a 100644
--- a/libs/api/tracker/application/src/lib/presence.service.ts
+++ b/libs/api/tracker/application/src/lib/presence.service.ts
@@ -57,6 +57,6 @@ export class PresenceService {
   private async assertCanView(viewerId: string, issueId: string) {
     const issue = await this.findIssues.findById(issueId);
     if (!issue || issue.trashedAt) throw new NotFoundError('Issue', issueId);
-    await this.access.assertCanView(issue.projectId, viewerId);
+    await this.access.assertCanViewIssue(issue, viewerId);
   }
 }
diff --git a/libs/api/tracker/application/src/lib/queries/can-view-project.query-handler.ts b/libs/api/tracker/application/src/lib/queries/can-view-project.query-handler.ts
index 8a9fd9b..39b7e36 100644
--- a/libs/api/tracker/application/src/lib/queries/can-view-project.query-handler.ts
+++ b/libs/api/tracker/application/src/lib/queries/can-view-project.query-handler.ts
@@ -9,6 +9,11 @@ export class CanViewProjectQueryHandler
   constructor(private readonly access: ReadAccess) {}
 
   async execute(query: CanViewProjectQuery): Promise<boolean> {
-    return this.access.canView(query.projectId, query.viewerId);
+    if (!(await this.access.canView(query.projectId, query.viewerId)))
+      return false;
+    return (
+      !query.wholeProject ||
+      !(await this.access.participantScope(query.projectId, query.viewerId))
+    );
   }
 }
diff --git a/libs/api/tracker/application/src/lib/queries/can-view-project.query.ts b/libs/api/tracker/application/src/lib/queries/can-view-project.query.ts
index e8b585e..de89fa1 100644
--- a/libs/api/tracker/application/src/lib/queries/can-view-project.query.ts
+++ b/libs/api/tracker/application/src/lib/queries/can-view-project.query.ts
@@ -5,6 +5,8 @@ export class CanViewProjectQuery extends Query<boolean> {
     /** Null: anonymous (public projects only). */
     public readonly viewerId: string | null,
     public readonly projectId: string,
+    /** The whole project (activity, releases…), not only a guest's tickets. */
+    public readonly wholeProject = false,
   ) {
     super();
   }
diff --git a/libs/api/tracker/application/src/lib/queries/get-activity.query-handler.ts b/libs/api/tracker/application/src/lib/queries/get-activity.query-handler.ts
index b1791fd..7e211ae 100644
--- a/libs/api/tracker/application/src/lib/queries/get-activity.query-handler.ts
+++ b/libs/api/tracker/application/src/lib/queries/get-activity.query-handler.ts
@@ -1,3 +1,5 @@
+import { NotFoundError } from '@task-stream/api/shared/domain';
+import { FindIssuesRepository } from '../ports/find-issues.repository';
 import { IQueryHandler, QueryHandler } from '@nestjs/cqrs';
 import { ActivityReadModel } from '@task-stream/api/tracker/domain';
 import { FindActivityRepository } from '../ports/find-activity.repository';
@@ -11,10 +13,23 @@ export class GetActivityQueryHandler
   constructor(
     private readonly findActivity: FindActivityRepository,
     private readonly access: ReadAccess,
+    private readonly findIssues: FindIssuesRepository,
   ) {}
 
   async execute(query: GetActivityQuery): Promise<ActivityReadModel[]> {
-    await this.access.assertCanView(query.projectId, query.viewerId);
+    // A ticket's history goes with the ticket; the project's feed is for
+    // whoever sees the whole project (not a guest).
+    if (query.issueId) {
+      const issue = this.access.assertFound(
+        await this.findIssues.findById(query.issueId),
+        'Issue',
+        query.issueId,
+      );
+      if (issue.projectId !== query.projectId)
+        throw new NotFoundError('Issue', query.issueId);
+      await this.access.assertCanViewIssue(issue, query.viewerId);
+    } else
+      await this.access.assertSeesWholeProject(query.projectId, query.viewerId);
     return this.findActivity.find({
       projectId: query.projectId,
       issueId: query.issueId,
diff --git a/libs/api/tracker/application/src/lib/queries/get-attachment.query-handler.ts b/libs/api/tracker/application/src/lib/queries/get-attachment.query-handler.ts
index e85f88b..ff394d7 100644
--- a/libs/api/tracker/application/src/lib/queries/get-attachment.query-handler.ts
+++ b/libs/api/tracker/application/src/lib/queries/get-attachment.query-handler.ts
@@ -21,7 +21,7 @@ export class GetAttachmentQueryHandler
       'Attachment',
       query.attachmentId,
     );
-    await this.access.assertCanView(issue.projectId, query.viewerId, {
+    await this.access.assertCanViewIssue(issue, query.viewerId, {
       entity: 'Attachment',
       ref: query.attachmentId,
     });
diff --git a/libs/api/tracker/application/src/lib/queries/get-board.query-handler.ts b/libs/api/tracker/application/src/lib/queries/get-board.query-handler.ts
index 97630f4..441c9f0 100644
--- a/libs/api/tracker/application/src/lib/queries/get-board.query-handler.ts
+++ b/libs/api/tracker/application/src/lib/queries/get-board.query-handler.ts
@@ -27,6 +27,11 @@ export class GetBoardQueryHandler
    */
   async execute(query: GetBoardQuery): Promise<BoardColumn[]> {
     await this.access.assertCanView(query.filter.projectId, query.viewerId);
+    const participantId =
+      (await this.access.participantScope(
+        query.filter.projectId,
+        query.viewerId,
+      )) ?? undefined;
     const project = await this.findProjects.findById(query.filter.projectId);
     const statuses = (
       project?.settings ?? DEFAULT_PROJECT_SETTINGS
@@ -35,6 +40,7 @@ export class GetBoardQueryHandler
       statuses.map(async (status) => {
         const page = await this.findIssues.search({
           ...query.filter,
+          participantId,
           statuses: [status.id],
           // Each column follows the backlog order.
           sort: IssueSort.RANK,
diff --git a/libs/api/tracker/application/src/lib/queries/get-comments.query-handler.ts b/libs/api/tracker/application/src/lib/queries/get-comments.query-handler.ts
index 1e3a158..dc177be 100644
--- a/libs/api/tracker/application/src/lib/queries/get-comments.query-handler.ts
+++ b/libs/api/tracker/application/src/lib/queries/get-comments.query-handler.ts
@@ -21,7 +21,7 @@ export class GetCommentsQueryHandler
       'Issue',
       query.issueId,
     );
-    await this.access.assertCanView(issue.projectId, query.viewerId, {
+    await this.access.assertCanViewIssue(issue, query.viewerId, {
       entity: 'Issue',
       ref: query.issueId,
     });
diff --git a/libs/api/tracker/application/src/lib/queries/get-epics.query-handler.ts b/libs/api/tracker/application/src/lib/queries/get-epics.query-handler.ts
index 5f3a54a..9f39570 100644
--- a/libs/api/tracker/application/src/lib/queries/get-epics.query-handler.ts
+++ b/libs/api/tracker/application/src/lib/queries/get-epics.query-handler.ts
@@ -14,7 +14,7 @@ export class GetEpicsQueryHandler
   ) {}
 
   async execute(query: GetEpicsQuery): Promise<EpicReadModel[]> {
-    await this.access.assertCanView(query.projectId, query.viewerId);
+    await this.access.assertSeesWholeProject(query.projectId, query.viewerId);
     return this.findIssues.epics(query.projectId);
   }
 }
diff --git a/libs/api/tracker/application/src/lib/queries/get-issue.query-handler.ts b/libs/api/tracker/application/src/lib/queries/get-issue.query-handler.ts
index 6ab4b8e..8b86c03 100644
--- a/libs/api/tracker/application/src/lib/queries/get-issue.query-handler.ts
+++ b/libs/api/tracker/application/src/lib/queries/get-issue.query-handler.ts
@@ -18,7 +18,7 @@ export class GetIssueQueryHandler
       ? await this.findIssues.findById(query.idOrKey)
       : await this.findIssues.findByKey(query.idOrKey.toUpperCase());
     const found = this.access.assertFound(issue, 'Issue', query.idOrKey);
-    await this.access.assertCanView(found.projectId, query.viewerId, {
+    await this.access.assertCanViewIssue(found, query.viewerId, {
       entity: 'Issue',
       ref: query.idOrKey,
     });
diff --git a/libs/api/tracker/application/src/lib/queries/get-issues-by-ids.query-handler.ts b/libs/api/tracker/application/src/lib/queries/get-issues-by-ids.query-handler.ts
index 99c99fc..e9f397b 100644
--- a/libs/api/tracker/application/src/lib/queries/get-issues-by-ids.query-handler.ts
+++ b/libs/api/tracker/application/src/lib/queries/get-issues-by-ids.query-handler.ts
@@ -23,6 +23,13 @@ export class GetIssuesByIdsQueryHandler
         await this.access.canView(projectId, query.viewerId),
       );
     }
-    return issues.filter((issue) => visible.get(issue.projectId));
+    const shown: IssueReadModel[] = [];
+    for (const issue of issues)
+      if (
+        visible.get(issue.projectId) &&
+        (await this.access.canViewIssue(issue, query.viewerId))
+      )
+        shown.push(issue);
+    return shown;
   }
 }
diff --git a/libs/api/tracker/application/src/lib/queries/get-project-analytics.query-handler.ts b/libs/api/tracker/application/src/lib/queries/get-project-analytics.query-handler.ts
index 684bd88..ecf9053 100644
--- a/libs/api/tracker/application/src/lib/queries/get-project-analytics.query-handler.ts
+++ b/libs/api/tracker/application/src/lib/queries/get-project-analytics.query-handler.ts
@@ -26,7 +26,7 @@ export class GetProjectAnalyticsQueryHandler
   async execute(
     query: GetProjectAnalyticsQuery,
   ): Promise<ProjectAnalyticsReadModel> {
-    await this.access.assertCanView(query.projectId, query.viewerId);
+    await this.access.assertSeesWholeProject(query.projectId, query.viewerId);
     const [project, issues, timeline] = await Promise.all([
       this.findProjects.findById(query.projectId),
       this.findIssues.findByProject(query.projectId),
diff --git a/libs/api/tracker/application/src/lib/queries/get-project-insights.query-handler.ts b/libs/api/tracker/application/src/lib/queries/get-project-insights.query-handler.ts
index fc93cc0..853abfc 100644
--- a/libs/api/tracker/application/src/lib/queries/get-project-insights.query-handler.ts
+++ b/libs/api/tracker/application/src/lib/queries/get-project-insights.query-handler.ts
@@ -32,7 +32,7 @@ export class GetProjectInsightsQueryHandler
   async execute(
     query: GetProjectInsightsQuery,
   ): Promise<ProjectInsightsReadModel> {
-    await this.access.assertCanView(query.projectId, query.viewerId);
+    await this.access.assertSeesWholeProject(query.projectId, query.viewerId);
     const [project, issues, timeline, sprints, releases, mentions] =
       await Promise.all([
         this.findProjects.findById(query.projectId),
diff --git a/libs/api/tracker/application/src/lib/queries/get-project-stats.query-handler.ts b/libs/api/tracker/application/src/lib/queries/get-project-stats.query-handler.ts
index 85b7824..0af3410 100644
--- a/libs/api/tracker/application/src/lib/queries/get-project-stats.query-handler.ts
+++ b/libs/api/tracker/application/src/lib/queries/get-project-stats.query-handler.ts
@@ -14,7 +14,7 @@ export class GetProjectStatsQueryHandler
   ) {}
 
   async execute(query: GetProjectStatsQuery): Promise<ProjectStatsReadModel> {
-    await this.access.assertCanView(query.projectId, query.viewerId);
+    await this.access.assertSeesWholeProject(query.projectId, query.viewerId);
     return this.findIssues.stats(query.projectId);
   }
 }
diff --git a/libs/api/tracker/application/src/lib/queries/get-release-burnup.query-handler.ts b/libs/api/tracker/application/src/lib/queries/get-release-burnup.query-handler.ts
index fc4e426..e6577d8 100644
--- a/libs/api/tracker/application/src/lib/queries/get-release-burnup.query-handler.ts
+++ b/libs/api/tracker/application/src/lib/queries/get-release-burnup.query-handler.ts
@@ -24,10 +24,14 @@ export class GetReleaseBurnupQueryHandler
       'Release',
       query.releaseId,
     );
-    await this.access.assertCanView(release.projectId, query.viewerId, {
-      entity: 'Release',
-      ref: query.releaseId,
-    });
+    await this.access.assertSeesWholeProject(
+      release.projectId,
+      query.viewerId,
+      {
+        entity: 'Release',
+        ref: query.releaseId,
+      },
+    );
     const [issues, timeline] = await Promise.all([
       this.findIssues.findByProject(release.projectId),
       this.findTimeline.findByProject(release.projectId),
diff --git a/libs/api/tracker/application/src/lib/queries/get-release-notes-draft.query.ts b/libs/api/tracker/application/src/lib/queries/get-release-notes-draft.query.ts
index cd7b973..e621402 100644
--- a/libs/api/tracker/application/src/lib/queries/get-release-notes-draft.query.ts
+++ b/libs/api/tracker/application/src/lib/queries/get-release-notes-draft.query.ts
@@ -36,10 +36,14 @@ export class GetReleaseNotesDraftQueryHandler
       'Release',
       query.releaseId,
     );
-    await this.access.assertCanView(release.projectId, query.viewerId, {
-      entity: 'Release',
-      ref: query.releaseId,
-    });
+    await this.access.assertSeesWholeProject(
+      release.projectId,
+      query.viewerId,
+      {
+        entity: 'Release',
+        ref: query.releaseId,
+      },
+    );
     const [page, project] = await Promise.all([
       this.findIssues.search({
         projectId: release.projectId,
diff --git a/libs/api/tracker/application/src/lib/queries/get-release-progress.query-handler.ts b/libs/api/tracker/application/src/lib/queries/get-release-progress.query-handler.ts
index c3b7d8a..0a17699 100644
--- a/libs/api/tracker/application/src/lib/queries/get-release-progress.query-handler.ts
+++ b/libs/api/tracker/application/src/lib/queries/get-release-progress.query-handler.ts
@@ -23,10 +23,14 @@ export class GetReleaseProgressQueryHandler
       'Release',
       query.releaseId,
     );
-    await this.access.assertCanView(release.projectId, query.viewerId, {
-      entity: 'Release',
-      ref: query.releaseId,
-    });
+    await this.access.assertSeesWholeProject(
+      release.projectId,
+      query.viewerId,
+      {
+        entity: 'Release',
+        ref: query.releaseId,
+      },
+    );
     return this.findIssues.releaseProgress(release.id);
   }
 }
diff --git a/libs/api/tracker/application/src/lib/queries/get-release.query-handler.ts b/libs/api/tracker/application/src/lib/queries/get-release.query-handler.ts
index 93ecce0..1c059d8 100644
--- a/libs/api/tracker/application/src/lib/queries/get-release.query-handler.ts
+++ b/libs/api/tracker/application/src/lib/queries/get-release.query-handler.ts
@@ -19,10 +19,14 @@ export class GetReleaseQueryHandler
       'Release',
       query.releaseId,
     );
-    await this.access.assertCanView(release.projectId, query.viewerId, {
-      entity: 'Release',
-      ref: query.releaseId,
-    });
+    await this.access.assertSeesWholeProject(
+      release.projectId,
+      query.viewerId,
+      {
+        entity: 'Release',
+        ref: query.releaseId,
+      },
+    );
     return release;
   }
 }
diff --git a/libs/api/tracker/application/src/lib/queries/get-releases.query-handler.ts b/libs/api/tracker/application/src/lib/queries/get-releases.query-handler.ts
index f222e22..d428344 100644
--- a/libs/api/tracker/application/src/lib/queries/get-releases.query-handler.ts
+++ b/libs/api/tracker/application/src/lib/queries/get-releases.query-handler.ts
@@ -14,7 +14,7 @@ export class GetReleasesQueryHandler
   ) {}
 
   async execute(query: GetReleasesQuery): Promise<ReleaseReadModel[]> {
-    await this.access.assertCanView(query.projectId, query.viewerId);
+    await this.access.assertSeesWholeProject(query.projectId, query.viewerId);
     return this.findReleases.findByProject(query.projectId);
   }
 }
diff --git a/libs/api/tracker/application/src/lib/queries/get-ticket-scope.query-handler.ts b/libs/api/tracker/application/src/lib/queries/get-ticket-scope.query-handler.ts
new file mode 100644
index 0000000..0601f32
--- /dev/null
+++ b/libs/api/tracker/application/src/lib/queries/get-ticket-scope.query-handler.ts
@@ -0,0 +1,14 @@
+import { IQueryHandler, QueryHandler } from '@nestjs/cqrs';
+import { GetTicketScopeQuery } from './get-ticket-scope.query';
+import { ReadAccess } from './read-access';
+
+@QueryHandler(GetTicketScopeQuery)
+export class GetTicketScopeQueryHandler
+  implements IQueryHandler<GetTicketScopeQuery, string | null>
+{
+  constructor(private readonly access: ReadAccess) {}
+
+  execute(query: GetTicketScopeQuery): Promise<string | null> {
+    return this.access.participantScope(query.projectId, query.viewerId);
+  }
+}
diff --git a/libs/api/tracker/application/src/lib/queries/get-ticket-scope.query.ts b/libs/api/tracker/application/src/lib/queries/get-ticket-scope.query.ts
new file mode 100644
index 0000000..ddec756
--- /dev/null
+++ b/libs/api/tracker/application/src/lib/queries/get-ticket-scope.query.ts
@@ -0,0 +1,14 @@
+import { Query } from '@nestjs/cqrs';
+
+/**
+ * Whose tickets the viewer sees of a project: null for all; their own id
+ * for a guest of a private project (only the tickets they take part in).
+ */
+export class GetTicketScopeQuery extends Query<string | null> {
+  constructor(
+    public readonly viewerId: string | null,
+    public readonly projectId: string,
+  ) {
+    super();
+  }
+}
diff --git a/libs/api/tracker/application/src/lib/queries/get-trash.query.ts b/libs/api/tracker/application/src/lib/queries/get-trash.query.ts
index 5ec982f..4e3f762 100644
--- a/libs/api/tracker/application/src/lib/queries/get-trash.query.ts
+++ b/libs/api/tracker/application/src/lib/queries/get-trash.query.ts
@@ -23,7 +23,7 @@ export class GetTrashQueryHandler
   ) {}
 
   async execute(query: GetTrashQuery): Promise<IssueReadModel[]> {
-    await this.access.assertCanView(query.projectId, query.viewerId);
+    await this.access.assertSeesWholeProject(query.projectId, query.viewerId);
     return this.findIssues.findTrashed(query.projectId);
   }
 }
diff --git a/libs/api/tracker/application/src/lib/queries/get-upcoming-releases.query-handler.ts b/libs/api/tracker/application/src/lib/queries/get-upcoming-releases.query-handler.ts
index a797d4c..bb62b79 100644
--- a/libs/api/tracker/application/src/lib/queries/get-upcoming-releases.query-handler.ts
+++ b/libs/api/tracker/application/src/lib/queries/get-upcoming-releases.query-handler.ts
@@ -1,3 +1,4 @@
+import { guestOnly } from './read-access';
 import { IQueryHandler, QueryHandler } from '@nestjs/cqrs';
 import { ReleaseReadModel } from '@task-stream/api/tracker/domain';
 import { FindProjectsRepository } from '../ports/find-projects.repository';
@@ -15,8 +16,11 @@ export class GetUpcomingReleasesQueryHandler
 
   async execute(query: GetUpcomingReleasesQuery): Promise<ReleaseReadModel[]> {
     const projects = await this.findProjects.findByMember(query.viewerId);
+    // A guest does not see a private project's releases.
     return this.findReleases.findUpcoming(
-      projects.map((project) => project.id),
+      projects
+        .filter((project) => !guestOnly(project, query.viewerId))
+        .map((project) => project.id),
       Math.min(query.limit, 50),
     );
   }
diff --git a/libs/api/tracker/application/src/lib/queries/index.ts b/libs/api/tracker/application/src/lib/queries/index.ts
index a12bae4..7a133f4 100644
--- a/libs/api/tracker/application/src/lib/queries/index.ts
+++ b/libs/api/tracker/application/src/lib/queries/index.ts
@@ -7,6 +7,7 @@ export * from './get-issues-by-ids.query';
 export * from './get-my-projects.query';
 export * from './get-project-analytics.query';
 export * from './get-project-insights.query';
+export * from './get-ticket-scope.query';
 export * from './get-project-stats.query';
 export * from './get-release-burnup.query';
 export * from './get-project.query';
diff --git a/libs/api/tracker/application/src/lib/queries/query-handlers.ts b/libs/api/tracker/application/src/lib/queries/query-handlers.ts
index 6371ca1..059bee2 100644
--- a/libs/api/tracker/application/src/lib/queries/query-handlers.ts
+++ b/libs/api/tracker/application/src/lib/queries/query-handlers.ts
@@ -10,6 +10,7 @@ import { GetMyProjectsQueryHandler } from './get-my-projects.query-handler';
 import { GetProjectQueryHandler } from './get-project.query-handler';
 import { GetProjectAnalyticsQueryHandler } from './get-project-analytics.query-handler';
 import { GetProjectInsightsQueryHandler } from './get-project-insights.query-handler';
+import { GetTicketScopeQueryHandler } from './get-ticket-scope.query-handler';
 import { GetProjectStatsQueryHandler } from './get-project-stats.query-handler';
 import { GetReleaseBurnupQueryHandler } from './get-release-burnup.query-handler';
 import { GetReleaseQueryHandler } from './get-release.query-handler';
@@ -36,6 +37,7 @@ export const QUERY_HANDLERS = [
   GetProjectQueryHandler,
   GetProjectAnalyticsQueryHandler,
   GetProjectInsightsQueryHandler,
+  GetTicketScopeQueryHandler,
   GetProjectStatsQueryHandler,
   GetReleaseBurnupQueryHandler,
   GetReleaseQueryHandler,
diff --git a/libs/api/tracker/application/src/lib/queries/read-access.ts b/libs/api/tracker/application/src/lib/queries/read-access.ts
index 6087e4a..545efba 100644
--- a/libs/api/tracker/application/src/lib/queries/read-access.ts
+++ b/libs/api/tracker/application/src/lib/queries/read-access.ts
@@ -1,6 +1,10 @@
 import { Injectable } from '@nestjs/common';
-import { NotFoundError } from '@task-stream/api/shared/domain';
-import { ProjectRole } from '@task-stream/api/tracker/domain';
+import { ForbiddenError, NotFoundError } from '@task-stream/api/shared/domain';
+import {
+  IssueReadModel,
+  ProjectReadModel,
+  ProjectRole,
+} from '@task-stream/api/tracker/domain';
 import { FindProjectsRepository } from '../ports/find-projects.repository';
 
 /**
@@ -35,6 +39,67 @@ export class ReadAccess {
     return null;
   }
 
+  /**
+   * Whose tickets the viewer sees of the project: null for all of them; for
+   * a guest of a private project, their own id (only the tickets they take
+   * part in).
+   */
+  async participantScope(
+    projectId: string,
+    viewerId: string | null,
+  ): Promise<string | null> {
+    if (!viewerId) return null;
+    const role = await this.findProjects.findRole(projectId, viewerId);
+    if (role !== ProjectRole.GUEST) return null;
+    const project = await this.findProjects.findById(projectId);
+    return project?.isPublic ? null : viewerId;
+  }
+
+  /**
+   * Views of the whole project (activity, statistics, releases, sprints…):
+   * not for a guest, who only sees their own tickets.
+   */
+  async assertSeesWholeProject(
+    projectId: string,
+    viewerId: string | null,
+    asked?: { entity: string; ref: string },
+  ): Promise<ProjectRole | null> {
+    const role = await this.assertCanView(projectId, viewerId, asked);
+    if (await this.participantScope(projectId, viewerId))
+      throw new ForbiddenError(
+        'Un invitado solo ve los tickets en los que participa',
+      );
+    return role;
+  }
+
+  /** The ticket, if the viewer may read it (a guest: only theirs). */
+  async assertCanViewIssue(
+    issue: IssueReadModel,
+    viewerId: string | null,
+    asked: { entity: string; ref: string } = {
+      entity: 'Issue',
+      ref: issue.key,
+    },
+  ): Promise<void> {
+    await this.assertCanView(issue.projectId, viewerId, asked);
+    const scope = await this.participantScope(issue.projectId, viewerId);
+    if (scope && !involves(issue, scope))
+      throw new NotFoundError(asked.entity, asked.ref);
+  }
+
+  async canViewIssue(
+    issue: IssueReadModel,
+    viewerId: string | null,
+  ): Promise<boolean> {
+    try {
+      await this.assertCanViewIssue(issue, viewerId);
+      return true;
+    } catch (error) {
+      if (error instanceof NotFoundError) return false;
+      throw error;
+    }
+  }
+
   async canView(projectId: string, viewerId: string | null): Promise<boolean> {
     try {
       await this.assertCanView(projectId, viewerId);
@@ -51,5 +116,24 @@ export class ReadAccess {
   }
 }
 
+/** Opened it, has it or follows it. */
+export function involves(issue: IssueReadModel, userId: string): boolean {
+  return (
+    issue.reporter?.id === userId ||
+    issue.assignee?.id === userId ||
+    (issue.watchers ?? []).some((w) => w.id === userId)
+  );
+}
+
+/** A guest of this private project: sees only the tickets they take part in. */
+export function guestOnly(project: ProjectReadModel, userId: string): boolean {
+  return (
+    !project.isPublic &&
+    project.members.some(
+      (m) => m.user.id === userId && m.role === ProjectRole.GUEST,
+    )
+  );
+}
+
 export const UUID =
   /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i;
diff --git a/libs/api/tracker/application/src/lib/queries/search-issues.query-handler.ts b/libs/api/tracker/application/src/lib/queries/search-issues.query-handler.ts
index 30db508..b42eb86 100644
--- a/libs/api/tracker/application/src/lib/queries/search-issues.query-handler.ts
+++ b/libs/api/tracker/application/src/lib/queries/search-issues.query-handler.ts
@@ -20,6 +20,11 @@ export class SearchIssuesQueryHandler
     if (watching && !query.viewerId) return { items: [], total: 0 };
     return this.findIssues.search({
       ...filter,
+      participantId:
+        (await this.access.participantScope(
+          query.filter.projectId,
+          query.viewerId,
+        )) ?? undefined,
       watcherId: watching ? (query.viewerId ?? undefined) : undefined,
       limit: Math.min(query.filter.limit, 200),
     });
diff --git a/libs/api/tracker/application/src/lib/queries/search-my-issues.query-handler.ts b/libs/api/tracker/application/src/lib/queries/search-my-issues.query-handler.ts
index 6aa8a4f..ddd77bf 100644
--- a/libs/api/tracker/application/src/lib/queries/search-my-issues.query-handler.ts
+++ b/libs/api/tracker/application/src/lib/queries/search-my-issues.query-handler.ts
@@ -7,6 +7,7 @@ import {
 import { FindIssuesRepository, Page } from '../ports/find-issues.repository';
 import { FindProjectsRepository } from '../ports/find-projects.repository';
 import { SearchMyIssuesQuery } from './search-my-issues.query';
+import { guestOnly } from './read-access';
 
 @QueryHandler(SearchMyIssuesQuery)
 export class SearchMyIssuesQueryHandler
@@ -41,8 +42,13 @@ export class SearchMyIssuesQueryHandler
       StatusCategory.IN_PROGRESS,
       StatusCategory.QA,
     ];
+    const guestProjectIds = projects
+      .filter((p) => guestOnly(p, query.viewerId))
+      .map((p) => p.id);
     return this.findIssues.searchAcross({
       projectIds: projects.map((project) => project.id),
+      guestProjectIds,
+      participantId: query.viewerId,
       priorities: filter.priorities?.length ? filter.priorities : undefined,
       typesByProject: bugTypes,
       dueBefore: filter.overdue
diff --git a/libs/api/tracker/application/src/lib/queries/sprint.queries.ts b/libs/api/tracker/application/src/lib/queries/sprint.queries.ts
index e0e8f2f..065f1e7 100644
--- a/libs/api/tracker/application/src/lib/queries/sprint.queries.ts
+++ b/libs/api/tracker/application/src/lib/queries/sprint.queries.ts
@@ -76,7 +76,7 @@ export class GetSprintsQueryHandler
   ) {}
 
   async execute(query: GetSprintsQuery): Promise<SprintReadModel[]> {
-    await this.access.assertCanView(query.projectId, query.viewerId);
+    await this.access.assertSeesWholeProject(query.projectId, query.viewerId);
     return this.findSprints.findByProject(query.projectId);
   }
 }
diff --git a/libs/api/tracker/domain/src/lib/issue/issue.ts b/libs/api/tracker/domain/src/lib/issue/issue.ts
index 95517cf..be172ff 100644
--- a/libs/api/tracker/domain/src/lib/issue/issue.ts
+++ b/libs/api/tracker/domain/src/lib/issue/issue.ts
@@ -200,6 +200,15 @@ export class Issue extends VersionedAggregateRoot implements IssueProps {
     this.apply(new IssueUpdatedEvent(actorId, this.id, this.projectId, patch));
   }
 
+  /** Opened it, has it, or follows it: what a guest may see. */
+  involves(userId: string): boolean {
+    return (
+      this.reporterId === userId ||
+      this.assigneeId === userId ||
+      this.watchers.includes(userId)
+    );
+  }
+
   /** Moves the ticket along its project's workflow. */
   changeStatus(
     actorId: string,
diff --git a/libs/api/tracker/domain/src/lib/project/project-role.ts b/libs/api/tracker/domain/src/lib/project/project-role.ts
index a29d745..fd12089 100644
--- a/libs/api/tracker/domain/src/lib/project/project-role.ts
+++ b/libs/api/tracker/domain/src/lib/project/project-role.ts
@@ -4,4 +4,9 @@ export enum ProjectRole {
   MEMBER = 'MEMBER',
   /** Read-only stakeholder (PM, client...). */
   VIEWER = 'VIEWER',
+  /**
+   * Someone from outside (a client): in a private project, sees only the
+   * tickets they take part in, opens tickets and comments on theirs.
+   */
+  GUEST = 'GUEST',
 }
diff --git a/libs/api/tracker/domain/src/lib/project/project.ts b/libs/api/tracker/domain/src/lib/project/project.ts
index 766139f..6c3439b 100644
--- a/libs/api/tracker/domain/src/lib/project/project.ts
+++ b/libs/api/tracker/domain/src/lib/project/project.ts
@@ -102,9 +102,31 @@ export class Project extends VersionedAggregateRoot implements ProjectProps {
     if (this.roleOf(userId) === ProjectRole.VIEWER) {
       throw new ForbiddenError(`Viewers cannot modify project ${this.key}`);
     }
+    if (this.roleOf(userId) === ProjectRole.GUEST) {
+      throw new ForbiddenError(
+        `Los invitados solo pueden abrir tickets en ${this.key} y comentar en los suyos`,
+      );
+    }
     this.assertNotArchived();
   }
 
+  /** Can open tickets and comment: members and guests (not viewers). */
+  assertCanReport(userId: string): void {
+    const role = this.roleOf(userId);
+    if (!role) {
+      throw new ForbiddenError(`You are not a member of project ${this.key}`);
+    }
+    if (role === ProjectRole.VIEWER) {
+      throw new ForbiddenError(`Viewers cannot modify project ${this.key}`);
+    }
+    this.assertNotArchived();
+  }
+
+  /** A guest of a private project: they only see the tickets they take part in. */
+  seesOnlyOwnTickets(userId: string): boolean {
+    return !this.isPublic && this.roleOf(userId) === ProjectRole.GUEST;
+  }
+
   /** Can change members, releases, settings and rules (owners and admins). */
   assertCanManage(userId: string): void {
     this.assertManages(userId);
diff --git a/libs/api/tracker/infrastructure/src/lib/mongo/find.repositories.ts b/libs/api/tracker/infrastructure/src/lib/mongo/find.repositories.ts
index 6d2e5b5..4df56fc 100644
--- a/libs/api/tracker/infrastructure/src/lib/mongo/find.repositories.ts
+++ b/libs/api/tracker/infrastructure/src/lib/mongo/find.repositories.ts
@@ -178,6 +178,14 @@ export class MongoFindIssuesRepository extends FindIssuesRepository {
     if (filter.dueBefore)
       query['dueDate'] = { $ne: null, $lt: filter.dueBefore };
     const and: Record<string, unknown>[] = [];
+    // Projects where the viewer is a guest: only the tickets they are part of.
+    if (filter.guestProjectIds?.length && filter.participantId)
+      and.push({
+        $or: [
+          { projectId: { $nin: filter.guestProjectIds } },
+          { $or: participation(filter.participantId) },
+        ],
+      });
     if (filter.typesByProject)
       and.push({
         $or: Object.entries(filter.typesByProject).map(
@@ -440,6 +448,13 @@ export class MongoFindIssuesRepository extends FindIssuesRepository {
   }
 }
 
+/** Opened it, has it or follows it. */
+const participation = (userId: string) => [
+  { 'reporter.id': userId },
+  { 'assignee.id': userId },
+  { 'watchers.id': userId },
+];
+
 function toMongoFilter(filter: IssueFilter): FilterQuery<IssueDoc> {
   // Tickets in the trash are only listed by the trash itself.
   const query: FilterQuery<IssueDoc> = {
@@ -476,6 +491,11 @@ function toMongoFilter(filter: IssueFilter): FilterQuery<IssueDoc> {
   if (filter.unassigned) query['assignee'] = null;
   else if (filter.assigneeId) query['assignee.id'] = filter.assigneeId;
   if (filter.watcherId) query['watchers.id'] = filter.watcherId;
+  if (filter.participantId)
+    query.$and = [
+      ...(query.$and ?? []),
+      { $or: participation(filter.participantId) },
+    ];
   if (filter.search?.trim()) {
     const pattern = new RegExp(escapeRegex(filter.search.trim()), 'i');
     query.$or = [
diff --git a/libs/api/tracker/presenters/src/lib/graphql/issue.resolver.ts b/libs/api/tracker/presenters/src/lib/graphql/issue.resolver.ts
index c7d21ee..d6c4785 100644
--- a/libs/api/tracker/presenters/src/lib/graphql/issue.resolver.ts
+++ b/libs/api/tracker/presenters/src/lib/graphql/issue.resolver.ts
@@ -223,8 +223,11 @@ export class IssueResolver {
     description:
       'Open tickets it waits for: the ones that block it and the ones it depends on',
   })
-  blockedBy(@Parent() issue: IssueReadModel) {
-    return this.blockers.blockedBy(issue);
+  blockedBy(
+    @CurrentUser() me: User | undefined,
+    @Parent() issue: IssueReadModel,
+  ) {
+    return this.blockers.blockedBy(issue, viewerOf(me));
   }
 
   @ResolveField(() => Boolean, { description: 'Whether I voted for it' })
diff --git a/libs/api/tracker/presenters/src/lib/http/refs.ts b/libs/api/tracker/presenters/src/lib/http/refs.ts
index ab9182d..1b34505 100644
--- a/libs/api/tracker/presenters/src/lib/http/refs.ts
+++ b/libs/api/tracker/presenters/src/lib/http/refs.ts
@@ -44,7 +44,7 @@ export class Refs {
   async issueDto(issue: IssueReadModel, viewerId: string | null) {
     const [allowedTransitions, blockedBy] = await Promise.all([
       this.workflows.allowedTransitions(issue),
-      this.blockers.blockedBy(issue),
+      this.blockers.blockedBy(issue, viewerId),
     ]);
     // Who voted is only for telling someone whether they did.
     const { voterIds, ...shown } = issue;
diff --git a/libs/web/tracker/application/src/lib/facades/project.facade.ts b/libs/web/tracker/application/src/lib/facades/project.facade.ts
index 18e7ed5..0fe14f9 100644
--- a/libs/web/tracker/application/src/lib/facades/project.facade.ts
+++ b/libs/web/tracker/application/src/lib/facades/project.facade.ts
@@ -66,6 +66,10 @@ export class ProjectFacade {
   readonly canManage = this.store.canManage;
   /** Any role but viewer. */
   readonly canContribute = this.store.canContribute;
+  /** Opens tickets and comments (members and guests). */
+  readonly canReport = this.store.canReport;
+  /** A guest of a private project: only their own tickets, no project-wide views. */
+  readonly seesOnlyOwnTickets = this.store.seesOnlyOwnTickets;
   /** Statuses, ticket types and areas of this project (names, colours, lookups). */
   readonly workflow = this.store.workflow;
   readonly savingSettings = this.store.savingSettings;
diff --git a/libs/web/tracker/application/src/lib/stores/project.store.ts b/libs/web/tracker/application/src/lib/stores/project.store.ts
index 476a569..a0874c8 100644
--- a/libs/web/tracker/application/src/lib/stores/project.store.ts
+++ b/libs/web/tracker/application/src/lib/stores/project.store.ts
@@ -107,11 +107,23 @@ export const ProjectStore = signalStore(
           (myRole() === ProjectRole.OWNER || myRole() === ProjectRole.ADMIN),
       ),
       canContribute: computed(
+        () =>
+          !project()?.archivedAt &&
+          !!myRole() &&
+          myRole() !== ProjectRole.VIEWER &&
+          myRole() !== ProjectRole.GUEST,
+      ),
+      /** Opens tickets and comments: members and guests, not viewers. */
+      canReport: computed(
         () =>
           !project()?.archivedAt &&
           !!myRole() &&
           myRole() !== ProjectRole.VIEWER,
       ),
+      /** A guest of a private project: sees only their own tickets. */
+      seesOnlyOwnTickets: computed(
+        () => !project()?.isPublic && myRole() === ProjectRole.GUEST,
+      ),
       members: computed(() => project()?.members ?? []),
       /** Statuses, types and areas of the project, with lookups. */
       workflow: computed(() => new Workflow(project()?.settings)),
@@ -262,42 +274,55 @@ export const ProjectStore = signalStore(
             ),
           ),
         ),
+        // A guest of a private project gets none of the project-wide views.
         details$: loaded$.pipe(
           switchMap(({ payload }) =>
-            merge(
-              projects
-                .stats(payload.id)
-                .pipe(map((stats) => projectApiEvents.statsLoaded(stats))),
-              reloadReleases(payload.id),
-              reloadSprints(payload.id),
-              activity
-                .list(payload.id)
-                .pipe(map((list) => projectApiEvents.activityLoaded(list))),
-            ),
+            store.seesOnlyOwnTickets()
+              ? []
+              : merge(
+                  projects
+                    .stats(payload.id)
+                    .pipe(map((stats) => projectApiEvents.statsLoaded(stats))),
+                  reloadReleases(payload.id),
+                  reloadSprints(payload.id),
+                  activity
+                    .list(payload.id)
+                    .pipe(map((list) => projectApiEvents.activityLoaded(list))),
+                ),
           ),
         ),
         live$: loaded$.pipe(
           switchMap(({ payload }) =>
-            merge(
-              realtime
-                .projectChanges(payload.id)
-                .pipe(
-                  map(({ project, deleted }) =>
-                    deleted
-                      ? projectRealtimeEvents.projectDeleted(project)
-                      : projectRealtimeEvents.projectChanged(project),
-                  ),
+            store.seesOnlyOwnTickets()
+              ? realtime
+                  .projectChanges(payload.id)
+                  .pipe(
+                    map(({ project, deleted }) =>
+                      deleted
+                        ? projectRealtimeEvents.projectDeleted(project)
+                        : projectRealtimeEvents.projectChanged(project),
+                    ),
+                  )
+              : merge(
+                  realtime
+                    .projectChanges(payload.id)
+                    .pipe(
+                      map(({ project, deleted }) =>
+                        deleted
+                          ? projectRealtimeEvents.projectDeleted(project)
+                          : projectRealtimeEvents.projectChanged(project),
+                      ),
+                    ),
+                  realtime
+                    .activity(payload.id)
+                    .pipe(map((a) => projectRealtimeEvents.activityAdded(a))),
+                  realtime
+                    .releaseChanges(payload.id)
+                    .pipe(map((r) => projectRealtimeEvents.releaseChanged(r))),
+                  realtime
+                    .sprintChanges(payload.id)
+                    .pipe(map((c) => projectRealtimeEvents.sprintChanged(c))),
                 ),
-              realtime
-                .activity(payload.id)
-                .pipe(map((a) => projectRealtimeEvents.activityAdded(a))),
-              realtime
-                .releaseChanges(payload.id)
-                .pipe(map((r) => projectRealtimeEvents.releaseChanged(r))),
-              realtime
-                .sprintChanges(payload.id)
-                .pipe(map((c) => projectRealtimeEvents.sprintChanged(c))),
-            ),
           ),
         ),
         /** Activity means tickets moved: refresh the dashboard (debounced). */
diff --git a/libs/web/tracker/domain/src/lib/models/enums.ts b/libs/web/tracker/domain/src/lib/models/enums.ts
index fc1be61..2b0997b 100644
--- a/libs/web/tracker/domain/src/lib/models/enums.ts
+++ b/libs/web/tracker/domain/src/lib/models/enums.ts
@@ -41,6 +41,8 @@ export enum ProjectRole {
   ADMIN = 'ADMIN',
   MEMBER = 'MEMBER',
   VIEWER = 'VIEWER',
+  /** From outside (a client): only the tickets they take part in. */
+  GUEST = 'GUEST',
 }
 
 export enum ReleaseStatus {
diff --git a/libs/web/tracker/infrastructure/src/lib/graphql/generated.ts b/libs/web/tracker/infrastructure/src/lib/graphql/generated.ts
index dcf0a5a..0e3bdc6 100644
--- a/libs/web/tracker/infrastructure/src/lib/graphql/generated.ts
+++ b/libs/web/tracker/infrastructure/src/lib/graphql/generated.ts
@@ -272,7 +272,7 @@ export type ProjectMemberInput = {
   userId: string;
 };
 
-export type ProjectRole = 'ADMIN' | 'MEMBER' | 'OWNER' | 'VIEWER';
+export type ProjectRole = 'ADMIN' | 'GUEST' | 'MEMBER' | 'OWNER' | 'VIEWER';
 
 /** The whole configuration (replaces the previous one). Statuses go in board order. */
 export type ProjectSettingsInput = {
diff --git a/libs/web/tracker/presenters/src/lib/pages/board.page.ts b/libs/web/tracker/presenters/src/lib/pages/board.page.ts
index 774c5df..9da6797 100644
--- a/libs/web/tracker/presenters/src/lib/pages/board.page.ts
+++ b/libs/web/tracker/presenters/src/lib/pages/board.page.ts
@@ -197,7 +197,7 @@ const NOBODY = '__nobody__';
         ><strong class="ts-mono">{{ board.total() }}</strong> tickets</span
       >
       <span class="ts-spacer"></span>
-      @if (project.canContribute()) {
+      @if (project.canReport()) {
         <pi-action-button
           color="primary"
           text="Nuevo ticket"
@@ -385,20 +385,22 @@ const NOBODY = '__nobody__';
             <pi-label>Estimación</pi-label>
           </pi-select-field>
         </div>
-        <div class="ts-form__row">
-          <pi-select-field
-            [formField]="f.assigneeId"
-            [options]="assigneeOptions()"
-          >
-            <pi-label>Asignar a</pi-label>
-          </pi-select-field>
-          <pi-select-field
-            [formField]="f.releaseId"
-            [options]="releaseOptions()"
-          >
-            <pi-label>Release</pi-label>
-          </pi-select-field>
-        </div>
+        @if (project.canContribute()) {
+          <div class="ts-form__row">
+            <pi-select-field
+              [formField]="f.assigneeId"
+              [options]="assigneeOptions()"
+            >
+              <pi-label>Asignar a</pi-label>
+            </pi-select-field>
+            <pi-select-field
+              [formField]="f.releaseId"
+              [options]="releaseOptions()"
+            >
+              <pi-label>Release</pi-label>
+            </pi-select-field>
+          </div>
+        }
         <pi-action-button
           size="w100"
           color="primary"
@@ -913,8 +915,9 @@ export class BoardPage {
       priority: v.priority as IssuePriority,
       area: v.area || null,
       storyPoints: v.storyPoints === '' ? null : Number(v.storyPoints),
-      assigneeId: v.assigneeId || null,
-      releaseId: v.releaseId || null,
+      // Planning it is for the team: a guest only opens it.
+      assigneeId: this.project.canContribute() ? v.assigneeId || null : null,
+      releaseId: this.project.canContribute() ? v.releaseId || null : null,
     });
     this.drawer.closeAll();
   }
diff --git a/libs/web/tracker/presenters/src/lib/pages/issue.page.ts b/libs/web/tracker/presenters/src/lib/pages/issue.page.ts
index 7fd30a4..96544e0 100644
--- a/libs/web/tracker/presenters/src/lib/pages/issue.page.ts
+++ b/libs/web/tracker/presenters/src/lib/pages/issue.page.ts
@@ -463,10 +463,10 @@ const MAX_FILE_BYTES = 25 * 1024 * 1024;
                   />
                 }
               </div>
-            } @else if (!project.canContribute()) {
+            } @else if (!project.canReport()) {
               <p class="ts-muted">Sin adjuntos.</p>
             }
-            @if (project.canContribute()) {
+            @if (project.canReport()) {
               <div class="ts-form">
                 <pi-file-upload
                   label="Capturas, logs, vídeos…"
@@ -721,9 +721,7 @@ const MAX_FILE_BYTES = 25 * 1024 * 1024;
                       </button>
                     </div>
                   </form>
-                } @else if (
-                  project.canContribute() && !thread.comment.deleted
-                ) {
+                } @else if (project.canReport() && !thread.comment.deleted) {
                   <button
                     type="button"
                     class="ts-plain-link ts-reply__open"
@@ -738,7 +736,7 @@ const MAX_FILE_BYTES = 25 * 1024 * 1024;
                 }
               </div>
             }
-            @if (project.canContribute()) {
+            @if (project.canReport()) {
               <form
                 class="ts-form"
                 (submit)="$event.preventDefault(); addComment()"
diff --git a/libs/web/tracker/presenters/src/lib/pages/members.page.ts b/libs/web/tracker/presenters/src/lib/pages/members.page.ts
index ae94d17..889b70d 100644
--- a/libs/web/tracker/presenters/src/lib/pages/members.page.ts
+++ b/libs/web/tracker/presenters/src/lib/pages/members.page.ts
@@ -231,6 +231,7 @@ export class MembersPage {
     ProjectRole.ADMIN,
     ProjectRole.MEMBER,
     ProjectRole.VIEWER,
+    ProjectRole.GUEST,
   ].map((value) => ({ value, label: ROLE[value] }));
   protected readonly candidates = computed(() => {
     const members = new Set(this.facade.members().map((m) => m.user.id));
diff --git a/libs/web/tracker/presenters/src/lib/pages/project-shell.page.ts b/libs/web/tracker/presenters/src/lib/pages/project-shell.page.ts
index 477406d..87c0688 100644
--- a/libs/web/tracker/presenters/src/lib/pages/project-shell.page.ts
+++ b/libs/web/tracker/presenters/src/lib/pages/project-shell.page.ts
@@ -91,15 +91,20 @@ import { projectTone, PUBLIC_TONE, ROLE } from '../ui/copy';
       <nav class="ts-tabs" aria-label="Secciones del proyecto">
         <a routerLink="board" routerLinkActive="is-active">Tablero</a>
         <a routerLink="list" routerLinkActive="is-active">Lista</a>
-        <a routerLink="backlog" routerLinkActive="is-active">Backlog</a>
-        <a routerLink="sprints" routerLinkActive="is-active">Sprints</a>
-        <a routerLink="calendar" routerLinkActive="is-active">Calendario</a>
-        <a routerLink="epics" routerLinkActive="is-active">Épicas</a>
-        <a routerLink="roadmap" routerLinkActive="is-active">Hoja de ruta</a>
-        <a routerLink="releases" routerLinkActive="is-active">Releases</a>
-        <a routerLink="dashboard" routerLinkActive="is-active">Seguimiento</a>
-        <a routerLink="analytics" routerLinkActive="is-active">Estadísticas</a>
-        <a routerLink="activity" routerLinkActive="is-active">Actividad</a>
+        <!-- A guest sees only their tickets: no project-wide views. -->
+        @if (!facade.seesOnlyOwnTickets()) {
+          <a routerLink="backlog" routerLinkActive="is-active">Backlog</a>
+          <a routerLink="sprints" routerLinkActive="is-active">Sprints</a>
+          <a routerLink="calendar" routerLinkActive="is-active">Calendario</a>
+          <a routerLink="epics" routerLinkActive="is-active">Épicas</a>
+          <a routerLink="roadmap" routerLinkActive="is-active">Hoja de ruta</a>
+          <a routerLink="releases" routerLinkActive="is-active">Releases</a>
+          <a routerLink="dashboard" routerLinkActive="is-active">Seguimiento</a>
+          <a routerLink="analytics" routerLinkActive="is-active"
+            >Estadísticas</a
+          >
+          <a routerLink="activity" routerLinkActive="is-active">Actividad</a>
+        }
         <a routerLink="members" routerLinkActive="is-active">Miembros</a>
         @if (facade.canManage() || facade.isOwner()) {
           <a routerLink="settings" routerLinkActive="is-active"
diff --git a/libs/web/tracker/presenters/src/lib/ui/copy.ts b/libs/web/tracker/presenters/src/lib/ui/copy.ts
index 40928fa..1987ce5 100644
--- a/libs/web/tracker/presenters/src/lib/ui/copy.ts
+++ b/libs/web/tracker/presenters/src/lib/ui/copy.ts
@@ -150,6 +150,7 @@ export const ROLE_TONE: Record<ProjectRole, string> = {
   [ProjectRole.ADMIN]: 'var(--ts-s-review)',
   [ProjectRole.MEMBER]: 'var(--ts-s-todo)',
   [ProjectRole.VIEWER]: 'var(--ts-s-cancelled)',
+  [ProjectRole.GUEST]: 'var(--ts-s-qa)',
 };
 
 export const ROLE: Record<ProjectRole, string> = {
@@ -157,6 +158,7 @@ export const ROLE: Record<ProjectRole, string> = {
   [ProjectRole.ADMIN]: 'Admin',
   [ProjectRole.MEMBER]: 'Miembro',
   [ProjectRole.VIEWER]: 'Lector',
+  [ProjectRole.GUEST]: 'Invitado',
 };
 
 export const RELEASE_STATUS: Record<