[codex] Add workspace diff viewer plugin (#6071)

## Thinking Path

> - Paperclip orchestrates AI agents for zero-human companies.
> - Operators need to inspect what agents changed inside execution and
project workspaces.
> - The existing workspace detail views did not provide a first-party
rich diff surface for staged, unstaged, head, renamed, binary,
oversized, and untracked changes.
> - The plugin system is the intended extension point for optional rich
UI surfaces.
> - This pull request adds a workspace diff plugin plus host services
and shared contracts so Changes tabs can render workspace diffs through
plugin slots.
> - The diff-renderer dependency should stay owned by the plugin package
rather than the core UI app.
> - The dependency surface must stay aligned with repository PR policy,
including intentionally omitting `pnpm-lock.yaml` from the PR.
> - The benefit is a more reviewable workspace surface without
hard-coding the renderer into every page.

## What Changed

- Added `@paperclipai/plugin-workspace-diff`, including diff
normalization, plugin manifest/worker/UI entrypoints, and focused plugin
tests.
- Kept `@pierre/diffs` scoped to `@paperclipai/plugin-workspace-diff`;
removed the core UI lab diff-renderer surface and direct UI package
dependency.
- Added shared workspace diff types and validators, plus plugin SDK
surface for workspace diff host services.
- Added server workspace diff service support and route coverage for
execution/project workspace diff flows.
- Wired Execution Workspace and Project Workspace Changes tabs to load
the diff plugin, including loading/error fallback behavior.
- Added UI tests and fixtures for the Changes tabs and plugin bridge
behavior.
- Added the new plugin package manifest to the Docker deps stage so PR
policy can validate dependency coverage.
- Addressed review hardening around empty untracked patches, workspace
path exposure, project workspace read capability checks, and default
base refs.

## Verification

- `pnpm --filter @paperclipai/plugin-workspace-diff test`
- `pnpm exec vitest run
packages/shared/src/validators/workspace-diff.test.ts
server/src/__tests__/workspace-diff-service.test.ts
ui/src/pages/ProjectWorkspaceDetail.test.tsx
ui/src/pages/ExecutionWorkspaceDetail.test.tsx`
- `pnpm exec vitest run ui/src/plugins/bridge.test.ts
server/src/__tests__/workspace-runtime-routes-authz.test.ts`
- `pnpm --filter @paperclipai/shared typecheck`
- `pnpm --filter @paperclipai/plugin-workspace-diff typecheck`
- `pnpm --filter @paperclipai/server typecheck`
- `pnpm --filter @paperclipai/ui typecheck`
- `node ./scripts/check-docker-deps-stage.mjs`
- Browser screenshot captured from the local worktree dev server:
https://files.catbox.moe/ofdpsp.png
- Confirmed branch is rebased onto `public-gh/master`,
`.github/workflows/pr.yml` is not included in the PR diff,
`ui/package.json` is not included in the PR diff, and `pnpm-lock.yaml`
is not included in the PR diff.

## Risks

- Medium UI integration risk: the Changes tab depends on the plugin slot
and host diff service path.
- Medium dependency risk: this adds `@pierre/diffs` in the plugin
package, but `pnpm-lock.yaml` is intentionally omitted per packaging
instructions because repository automation manages lockfile updates.
- Current CI blocker: downstream frozen installs fail until the
repository policy path for new plugin package dependencies is chosen.
- Diff rendering edge cases are covered for common working-tree and head
diff states, but very large repositories may still expose performance
limits.
- No migrations are included.

> For core feature work, check [`ROADMAP.md`](ROADMAP.md) first and
discuss it in `#dev` before opening the PR. Feature PRs that overlap
with planned core work may need to be redirected — check the roadmap
first. See `CONTRIBUTING.md`.

## Model Used

- OpenAI Codex, GPT-5 class coding model, tool-enabled local execution
environment. Exact context window was not exposed by the runtime.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] If this change affects the UI, I have included before/after
screenshots
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] I will address all Greptile and reviewer comments before
requesting merge

---------

Co-authored-by: Paperclip <noreply@paperclip.ing>

server/src/__tests__/execution-workspaces-routes.test.ts

@@ -25,15 +25,15 @@ vi.mock("../services/index.js", () => ({
   workspaceOperationService: () => mockWorkspaceOperationService,
 }));
 
-function createApp() {
+function createApp(companyIds = ["company-1"]) {
   const app = express();
   app.use(express.json());
   app.use((req, _res, next) => {
     (req as any).actor = {
       type: "board",
       userId: "local-board",
-      companyIds: ["company-1"],
-      source: "local_implicit",
+      companyIds,
+      source: "session",
       isInstanceAdmin: false,
     };
     next();
@@ -55,6 +55,7 @@ describe.sequential("execution workspace routes", () => {
         projectWorkspaceId: null,
       },
     ]);
+    mockExecutionWorkspaceService.getById.mockResolvedValue(null);
   });
 
   it("uses summary mode for lightweight workspace lookups", async () => {
@@ -79,4 +80,5 @@ describe.sequential("execution workspace routes", () => {
     });
     expect(mockExecutionWorkspaceService.list).not.toHaveBeenCalled();
   });
+
 });

server/src/__tests__/heartbeat-issue-liveness-escalation.test.ts

@@ -800,4 +800,43 @@ describeEmbeddedPostgres("heartbeat issue graph liveness escalation", () => {
     expect(blockers.some((row) => row.blockerIssueId === closedEscalationId)).toBe(false);
     expect(blockers.some((row) => row.blockerIssueId === freshEscalation?.id)).toBe(true);
   });
+
+  it("removes closed liveness escalations from blocker relations during reconciliation", async () => {
+    await enableAutoRecovery();
+    const { companyId, blockedIssueId, blockerIssueId } = await seedBlockedChain();
+    const heartbeat = heartbeatService(db);
+
+    const first = await heartbeat.reconcileIssueGraphLiveness();
+    expect(first.escalationsCreated).toBe(1);
+
+    const escalations = await db
+      .select()
+      .from(issues)
+      .where(
+        and(
+          eq(issues.companyId, companyId),
+          eq(issues.originKind, "harness_liveness_escalation"),
+        ),
+      );
+    expect(escalations).toHaveLength(1);
+
+    await db
+      .update(issues)
+      .set({ status: "done", blockedByIssueIds: [] })
+      .where(eq(issues.id, escalations[0]!.id));
+    await db
+      .update(issues)
+      .set({ status: "done", blockedByIssueIds: [] })
+      .where(eq(issues.id, blockerIssueId));
+
+    const second = await heartbeat.reconcileIssueGraphLiveness();
+    expect(second.obsoleteRecoveryBlockerRelationsRemoved).toBe(0);
+    expect(second.doneRecoveryBlockerRelationsRemoved).toBe(1);
+
+    const blockers = await db
+      .select({ blockerIssueId: issueRelations.issueId })
+      .from(issueRelations)
+      .where(eq(issueRelations.relatedIssueId, blockedIssueId));
+    expect(blockers.some((row) => row.blockerIssueId === escalations[0]!.id)).toBe(false);
+  });
 });

server/src/__tests__/plugin-execution-workspace-bridge.test.ts

@@ -0,0 +1,54 @@
+import { describe, expect, it, vi } from "vitest";
+import { createHostClientHandlers } from "../../../packages/plugins/sdk/src/host-client-factory.js";
+import { PLUGIN_RPC_ERROR_CODES } from "../../../packages/plugins/sdk/src/protocol.js";
+
+describe("plugin execution workspace bridge", () => {
+  it("routes metadata reads through the host client when the capability is declared", async () => {
+    const get = vi.fn().mockResolvedValue({
+      id: "workspace-1",
+      companyId: "company-1",
+      projectId: "project-1",
+      projectWorkspaceId: null,
+      path: "/tmp/workspace-1",
+      cwd: "/tmp/workspace-1",
+      repoUrl: null,
+      baseRef: "main",
+      branchName: "feature/workspace-1",
+      providerType: "git_worktree",
+      providerMetadata: null,
+    });
+    const handlers = createHostClientHandlers({
+      pluginId: "workspace-plugin",
+      capabilities: ["execution.workspaces.read"],
+      services: {
+        executionWorkspaces: { get },
+      } as any,
+    });
+
+    await expect(
+      handlers["executionWorkspaces.get"]({ workspaceId: "workspace-1", companyId: "company-1" }),
+    ).resolves.toMatchObject({
+      id: "workspace-1",
+      cwd: "/tmp/workspace-1",
+    });
+    expect(get).toHaveBeenCalledWith({ workspaceId: "workspace-1", companyId: "company-1" });
+  });
+
+  it("rejects metadata reads when the plugin lacks execution.workspace read access", async () => {
+    const get = vi.fn();
+    const handlers = createHostClientHandlers({
+      pluginId: "workspace-plugin",
+      capabilities: [],
+      services: {
+        executionWorkspaces: { get },
+      } as any,
+    });
+
+    await expect(
+      handlers["executionWorkspaces.get"]({ workspaceId: "workspace-1", companyId: "company-1" }),
+    ).rejects.toMatchObject({
+      code: PLUGIN_RPC_ERROR_CODES.CAPABILITY_DENIED,
+    });
+    expect(get).not.toHaveBeenCalled();
+  });
+});

server/src/__tests__/plugin-orchestration-apis.test.ts

@@ -11,6 +11,7 @@ import {
   companies,
   costEvents,
   createDb,
+  executionWorkspaces,
   heartbeatRuns,
   issueRelations,
   issues,
@@ -67,6 +68,7 @@ describeEmbeddedPostgres("plugin orchestration APIs", () => {
     await db.delete(agentWakeupRequests);
     await db.delete(issueRelations);
     await db.delete(issues);
+    await db.delete(executionWorkspaces);
     await db.delete(pluginManagedResources);
     await db.delete(projects);
     await db.delete(plugins);
@@ -107,6 +109,61 @@ describeEmbeddedPostgres("plugin orchestration APIs", () => {
     return root;
   }
 
+  it("returns plugin-safe execution workspace metadata scoped to the company", async () => {
+    const { companyId } = await seedCompanyAndAgent();
+    const otherCompanyId = randomUUID();
+    const projectId = randomUUID();
+    const workspaceId = randomUUID();
+    await db.insert(companies).values({
+      id: otherCompanyId,
+      name: "Other",
+      issuePrefix: issuePrefix(otherCompanyId),
+      requireBoardApprovalForNewAgents: false,
+    });
+    await db.insert(projects).values({
+      id: projectId,
+      companyId,
+      name: "Workspaces",
+      status: "in_progress",
+    });
+    await db.insert(executionWorkspaces).values({
+      id: workspaceId,
+      companyId,
+      projectId,
+      mode: "isolated_workspace",
+      strategyType: "git_worktree",
+      name: "Feature workspace",
+      status: "active",
+      cwd: "/tmp/paperclip-feature",
+      repoUrl: "https://example.com/paperclip.git",
+      baseRef: "main",
+      branchName: "feature/workspace",
+      providerType: "git_worktree",
+      providerRef: "/tmp/paperclip-feature",
+      metadata: {
+        providerMetadata: { sandboxId: "sandbox-1" },
+        workspaceRealizationRequest: { hiddenInternal: true },
+      },
+    });
+
+    const services = buildHostServices(db, "plugin-record-id", "paperclip.workspace", createEventBusStub());
+
+    await expect(services.executionWorkspaces.get({ workspaceId, companyId })).resolves.toMatchObject({
+      id: workspaceId,
+      companyId,
+      projectId,
+      projectWorkspaceId: null,
+      path: "/tmp/paperclip-feature",
+      cwd: "/tmp/paperclip-feature",
+      repoUrl: "https://example.com/paperclip.git",
+      baseRef: "main",
+      branchName: "feature/workspace",
+      providerType: "git_worktree",
+      providerMetadata: { sandboxId: "sandbox-1" },
+    });
+    await expect(services.executionWorkspaces.get({ workspaceId, companyId: otherCompanyId })).resolves.toBeNull();
+  });
+
   it("creates plugin-origin issues with full orchestration fields and audit activity", async () => {
     const { companyId, agentId } = await seedCompanyAndAgent();
     const blockerIssueId = randomUUID();

server/src/__tests__/plugin-sdk-testing.test.ts

@@ -3,6 +3,63 @@ import type { PaperclipPluginManifestV1 } from "@paperclipai/shared";
 import { createTestHarness } from "@paperclipai/plugin-sdk/testing";
 
 describe("plugin SDK test harness", () => {
+  it("returns scoped execution workspace metadata with the read capability", async () => {
+    const manifest: PaperclipPluginManifestV1 = {
+      id: "paperclip.test-execution-workspace-metadata",
+      apiVersion: 1,
+      version: "0.1.0",
+      displayName: "Execution Workspace Metadata",
+      description: "Test plugin",
+      author: "Paperclip",
+      categories: ["automation"],
+      capabilities: ["execution.workspaces.read"],
+      entrypoints: { worker: "./dist/worker.js" },
+    };
+    const harness = createTestHarness({ manifest });
+    harness.seed({
+      executionWorkspaces: [{
+        id: "workspace-1",
+        companyId: "company-1",
+        projectId: "project-1",
+        projectWorkspaceId: "project-workspace-1",
+        path: "/tmp/paperclip-test",
+        cwd: "/tmp/paperclip-test",
+        repoUrl: "https://example.com/repo.git",
+        baseRef: "main",
+        branchName: "feature/test",
+        providerType: "git_worktree",
+        providerMetadata: { sandboxId: "sandbox-1" },
+      }],
+    });
+
+    await expect(harness.ctx.executionWorkspaces.get("workspace-1", "company-1")).resolves.toMatchObject({
+      id: "workspace-1",
+      cwd: "/tmp/paperclip-test",
+      branchName: "feature/test",
+      providerMetadata: { sandboxId: "sandbox-1" },
+    });
+    await expect(harness.ctx.executionWorkspaces.get("workspace-1", "company-2")).resolves.toBeNull();
+  });
+
+  it("requires execution.workspaces.read before returning workspace metadata", async () => {
+    const manifest: PaperclipPluginManifestV1 = {
+      id: "paperclip.test-missing-execution-workspace-read",
+      apiVersion: 1,
+      version: "0.1.0",
+      displayName: "Missing Workspace Read Capability",
+      description: "Test plugin",
+      author: "Paperclip",
+      categories: ["automation"],
+      capabilities: [],
+      entrypoints: { worker: "./dist/worker.js" },
+    };
+    const harness = createTestHarness({ manifest });
+
+    await expect(harness.ctx.executionWorkspaces.get("workspace-1", "company-1")).rejects.toThrow(
+      "missing required capability 'execution.workspaces.read'",
+    );
+  });
+
   it("requires skills.managed capability before resetting a missing declaration", async () => {
     const manifest: PaperclipPluginManifestV1 = {
       id: "paperclip.test-missing-managed-skill-capability",