diff --git a/docs/data-model.md b/docs/data-model.md
index dc65096b66..296720fe08 100644
--- a/docs/data-model.md
+++ b/docs/data-model.md
@@ -92,6 +92,7 @@ Each agent is stored as a separate JSON file, grouped by project directory.
 | `lastUserMessageAt`  | `string?` (ISO 8601)                     | Last user message timestamp                                                                                                                                                                                                                                                                                                                                                         |
 | `title`              | `string?`                                | User-visible title                                                                                                                                                                                                                                                                                                                                                                  |
 | `labels`             | `Record<string, string>`                 | Key-value labels (default `{}`). Paseo uses `paseo.parent-agent-id` for parentage and client-scoped `paseo.open-agent-tab.*` labels while managed subagent tabs are open — see [agent-lifecycle.md](./agent-lifecycle.md)                                                                                                                                                           |
+| `metadata`           | `Record<string, JsonValue>`              | Plugin-owned data (default `{}`). Paseo stores and forwards it and never reads a key. Set at creation or through `agent.metadata.update.request`; `null` in a patch removes a key                                                                                                                                                                                                   |
 | `lastStatus`         | `AgentStatus`                            | One of: `"initializing"`, `"idle"`, `"running"`, `"error"`, `"closed"`. `closed` means the record is resumable but has no live provider runtime; archive remains represented separately by `archivedAt`.                                                                                                                                                                            |
 | `lastModeId`         | `string?`                                | Last active mode ID                                                                                                                                                                                                                                                                                                                                                                 |
 | `config`             | `SerializableConfig?`                    | Agent session configuration (see below)                                                                                                                                                                                                                                                                                                                                             |
@@ -478,6 +479,7 @@ Array of workspace records. A workspace is a specific working directory within a
 | `archivedAt`                   | `string \| null` (ISO 8601)                                  | Soft-delete; required nullable                                                                                                                                                                |
 | `autoArchivedChangeRequestUrl` | `string \| null`                                             | Change request whose merged state triggered auto-archive. Restore replaces it with the current merged change request, when present, so repeated snapshots cannot archive the workspace again. |
 | `labels`                       | `string[]?`                                                  | Normalized display names assigned from this host's shared label catalog. Missing means unlabelled.                                                                                            |
+| `metadata`                     | `Record<string, JsonValue>`                                  | Plugin-owned data (default `{}`). Paseo stores and forwards it and never reads a key. Set at creation or through `workspace.metadata.update.request`.                                         |
 | `pinnedAt`                     | `string \| null` (ISO 8601)                                  | Pinned-to-top-of-sidebar timestamp; null means "not pinned"                                                                                                                                   |
 | `untrustedSource`              | `{ kind: "change_request", forge, number, headRepository }?` | Provenance captured when a cross-repository change request creates the workspace. Missing means repository automation is allowed; explicit setup removes the field.                           |
 
diff --git a/packages/client/src/daemon-client.test.ts b/packages/client/src/daemon-client.test.ts
index ca6b615eef..26e7dc88ea 100644
--- a/packages/client/src/daemon-client.test.ts
+++ b/packages/client/src/daemon-client.test.ts
@@ -3727,6 +3727,35 @@ test("rejects an internal create before sending when the host predates internal
   expect(mock.sent).toHaveLength(0);
 });
 
+test("metadata needs a host that advertises entityMetadata and sends nothing to one that does not", async () => {
+  const mock = createMockTransport();
+  const client = new DaemonClient({
+    url: "ws://test",
+    clientId: "clsk_unit_test",
+    logger: createMockLogger(),
+    reconnect: { enabled: false },
+    transportFactory: () => mock.transport,
+  });
+  clients.push(client);
+  const connectPromise = client.connect();
+  mock.triggerOpen({ features: {} });
+  await connectPromise;
+
+  const update = "Update the host to use metadata.";
+  await expect(
+    client.createAgent({ provider: "codex", cwd: "/tmp/project", metadata: { key: "value" } }),
+  ).rejects.toThrow(update);
+  await expect(
+    client.createWorkspace({
+      source: { kind: "directory", path: "/tmp/project" },
+      metadata: { key: "value" },
+    }),
+  ).rejects.toThrow(update);
+  await expect(client.setAgentMetadata("agent-1", { key: null })).rejects.toThrow(update);
+  await expect(client.setWorkspaceMetadata("workspace-1", { key: null })).rejects.toThrow(update);
+  expect(mock.sent).toHaveLength(0);
+});
+
 test("sends internal workspace creation and internal listings only to hosts that support them", async () => {
   const logger = createMockLogger();
   const mock = createMockTransport();
diff --git a/packages/client/src/daemon-client.ts b/packages/client/src/daemon-client.ts
index 512db1da1d..d9add1631b 100644
--- a/packages/client/src/daemon-client.ts
+++ b/packages/client/src/daemon-client.ts
@@ -21,6 +21,7 @@ import {
 } from "./connection/index.js";
 import { CreationClient } from "./creation/index.js";
 import type { CreationSnapshot } from "@getpaseo/protocol/messages";
+import type { JsonValue } from "@getpaseo/protocol/agent-types";
 import type { z } from "zod";
 import type { SessionEventSubscription } from "@getpaseo/protocol/messages";
 import type { LocalSpeechModel } from "@getpaseo/protocol/speech/rpc-schemas";
@@ -509,11 +510,15 @@ export interface CreateAgentRequestOptions extends AgentConfigOverrides {
   worktreeName?: string;
   requestId?: string;
   labels?: Record<string, string>;
+  /** Plugin-owned data stored on the agent. Needs a host with `entityMetadata`. */
+  metadata?: CreateAgentRequestMessage["metadata"];
 }
 
 export interface CreateWorkspaceRequestOptions {
   source: WorkspaceCreateRequest["source"];
   title?: string;
+  /** Plugin-owned data stored on the workspace. Needs a host with `entityMetadata`. */
+  metadata?: WorkspaceCreateRequest["metadata"];
   /** Workspace discovery visibility; contents retain normal durability. */
   background?: boolean;
   callerAgentId?: string;
@@ -3251,6 +3256,13 @@ export class DaemonClient {
     legacyWorkspace: (input) => this.createLegacyWorkspace(input, input.requestId),
   });
 
+  // Entity metadata is gated once at the transport boundary.
+  private requireEntityMetadata(): void {
+    if (this.lastServerInfoMessage?.features?.entityMetadata !== true) {
+      throw new Error("Update the host to use metadata.");
+    }
+  }
+
   // Background workspaces are gated once at the transport boundary.
   private requireBackgroundWorkspaces(): void {
     if (this.lastServerInfoMessage?.features?.backgroundWorkspaces !== true) {
@@ -3269,6 +3281,7 @@ export class DaemonClient {
       );
     }
     if (options.background !== undefined) this.requireBackgroundWorkspaces();
+    if (options.metadata !== undefined) this.requireEntityMetadata();
     const config = resolveAgentConfig(options);
     const result = await this.creations.createAgent({
       ...options,
@@ -3505,6 +3518,42 @@ export class DaemonClient {
     return { removedWorkspaceIds: payload.removedWorkspaceIds };
   }
 
+  /** Top-level keys replace; `null` removes the key. Resolves to the agent's metadata afterwards. */
+  async setAgentMetadata(
+    agentId: string,
+    patch: Record<string, JsonValue>,
+    requestId?: string,
+  ): Promise<Record<string, JsonValue>> {
+    this.requireEntityMetadata();
+    const payload =
+      await this.sendNamespacedCorrelatedSessionRequest<"agent.metadata.update.response">({
+        requestId,
+        message: { type: "agent.metadata.update.request", agentId, patch },
+      });
+    if (!payload.accepted || !payload.metadata) {
+      throw new Error(payload.error ?? "setAgentMetadata rejected");
+    }
+    return payload.metadata;
+  }
+
+  /** Top-level keys replace; `null` removes the key. Resolves to the workspace's metadata afterwards. */
+  async setWorkspaceMetadata(
+    workspaceId: string,
+    patch: Record<string, JsonValue>,
+    requestId?: string,
+  ): Promise<Record<string, JsonValue>> {
+    this.requireEntityMetadata();
+    const payload =
+      await this.sendNamespacedCorrelatedSessionRequest<"workspace.metadata.update.response">({
+        requestId,
+        message: { type: "workspace.metadata.update.request", workspaceId, patch },
+      });
+    if (!payload.accepted || !payload.metadata) {
+      throw new Error(payload.error ?? "setWorkspaceMetadata rejected");
+    }
+    return payload.metadata;
+  }
+
   async setWorkspaceTitle(
     workspaceId: string,
     title: string | null,
@@ -5058,6 +5107,8 @@ export class DaemonClient {
     if (input.background !== undefined || input.callerAgentId) this.requireBackgroundWorkspaces();
     if (input.agent?.background !== undefined)
       throw new Error("Configure background on the workspace, not its initial agent.");
+    if (input.metadata !== undefined || input.agent?.metadata !== undefined)
+      this.requireEntityMetadata();
     let agentConfig = input.agent ? resolveAgentConfig(input.agent) : undefined;
     if (agentConfig && this.carriesLegacyOptions(agentConfig)) {
       agentConfig = await this.routeLegacyCreateConfig(agentConfig);
@@ -7687,6 +7738,7 @@ function resolveAgentConfig(options: CreateAgentRequestOptions): AgentSessionCon
     worktreeName: _worktreeName,
     requestId: _requestId,
     labels: _labels,
+    metadata: _metadata,
     ...overrides
   } = options;
 
diff --git a/packages/client/src/index.ts b/packages/client/src/index.ts
index b476a35cda..d5c7cc6bf0 100644
--- a/packages/client/src/index.ts
+++ b/packages/client/src/index.ts
@@ -8,7 +8,7 @@ export type { HostAdd, HostUpdate, HostSummary, HostDirectory } from "@getpaseo/
 import type { OwnedSubscription } from "./connection/index.js";
 export type { OwnedSubscription, SubscriptionObserver } from "./connection/index.js";
 import type { DaemonClientConfig } from "./daemon-client.js";
-import type { AgentPermissionResponse } from "@getpaseo/protocol/agent-types";
+import type { AgentPermissionResponse, JsonValue } from "@getpaseo/protocol/agent-types";
 import type {
   AgentSnapshotPayload,
   CreationSnapshot,
@@ -184,6 +184,8 @@ export interface PaseoWorkspaceHandle {
   readonly directory: string | null;
   readonly name: string | null;
   readonly status: PaseoWorkspace["status"] | null;
+  /** Data plugins stored on the workspace. Paseo never reads a key. */
+  readonly metadata: NonNullable<PaseoWorkspace["metadata"]> | null;
   readonly agents: {
     create(options: PaseoWorkspaceAgentCreateOptions): Promise<PaseoAgentHandle>;
   };
@@ -191,6 +193,8 @@ export interface PaseoWorkspaceHandle {
   current(): PaseoWorkspace | null;
   refresh(options?: { requestId?: string }): Promise<PaseoWorkspace | null>;
   setTitle(title: string | null, requestId?: string): Promise<{ title: string | null }>;
+  /** Top-level keys replace; `null` removes the key. Needs a host with `entityMetadata`. */
+  setMetadata(patch: Record<string, JsonValue>): Promise<void>;
   archive(requestId?: string): Promise<PaseoWorkspaceArchiveResult>;
   /**
    * Subscribes to already-emitted daemon workspace_update events for this id.
@@ -274,6 +278,8 @@ export interface PaseoAgentCreateOptions {
   background?: CreateAgentRequestMessage["background"];
   requestId?: string;
   labels?: Record<string, string>;
+  /** Data plugins store on the agent: JSON values under keys such as `"linear.issue"`. */
+  metadata?: CreateAgentRequestMessage["metadata"];
 }
 
 export type PaseoWorkspaceAgentCreateOptions = Omit<PaseoAgentCreateOptions, "cwd">;
@@ -376,6 +382,8 @@ export interface PaseoAgentHandle {
   readonly options: NonNullable<PaseoAgent["options"]> | null;
   /** How the provider wants its options drawn. Controls hold no value; read `options`. */
   readonly controls: NonNullable<PaseoAgent["controls"]> | null;
+  /** Data plugins stored on the agent. Paseo never reads a key. */
+  readonly metadata: NonNullable<PaseoAgent["metadata"]> | null;
   readonly runtimeInfo: NonNullable<PaseoAgent["runtimeInfo"]> | null;
   readonly archivedAt: NonNullable<PaseoAgent["archivedAt"]> | null;
   readonly timeline: PaseoAgentTimelineHandle;
@@ -394,6 +402,8 @@ export interface PaseoAgentHandle {
    * provider has applied the patch; a provider that cannot apply a key live rejects it.
    */
   setOptions(patch: Record<string, unknown>): Promise<void>;
+  /** Top-level keys replace; `null` removes the key. Needs a host with `entityMetadata`. */
+  setMetadata(patch: Record<string, JsonValue>): Promise<void>;
   /** Sends a prompt and resolves when that turn finishes or needs attention. */
   run(text: string, options?: PaseoAgentRunOptions): Promise<PaseoAgentRunResult>;
   /** Waits for the current turn, including one started with `prompt`. */
@@ -899,6 +909,9 @@ function createWorkspaceHandleFactory(
       get status() {
         return current?.status ?? null;
       },
+      get metadata() {
+        return current?.metadata ?? null;
+      },
       agents: {
         create: async (options) => {
           const snapshot = current ?? (await refresh());
@@ -918,6 +931,10 @@ function createWorkspaceHandleFactory(
       current: () => current,
       refresh,
       setTitle: (title, requestId) => daemonClient.setWorkspaceTitle(id, title, requestId),
+      setMetadata: async (patch) => {
+        const metadata = await daemonClient.setWorkspaceMetadata(id, patch);
+        if (current) current = { ...current, metadata };
+      },
       archive: async (requestId) => {
         const result = await daemonClient.archiveWorkspace(id, requestId);
         if (current) {
@@ -1025,6 +1042,9 @@ function createAgentHandleFactory(
       get controls() {
         return current?.controls ?? null;
       },
+      get metadata() {
+        return current?.metadata ?? null;
+      },
       get runtimeInfo() {
         return current?.runtimeInfo ?? null;
       },
@@ -1049,6 +1069,10 @@ function createAgentHandleFactory(
       setOptions: async (patch) => {
         await daemonClient.setAgentOptions(id, patch);
       },
+      setMetadata: async (patch) => {
+        const metadata = await daemonClient.setAgentMetadata(id, patch);
+        if (current) current = { ...current, metadata };
+      },
       respondToPermission: async ({ requestId, response }) => {
         await daemonClient.respondToPermission(id, requestId, response);
       },
diff --git a/packages/plugin/src/server/lifecycle.ts b/packages/plugin/src/server/lifecycle.ts
index 20df9c2dcb..256ff45c0f 100644
--- a/packages/plugin/src/server/lifecycle.ts
+++ b/packages/plugin/src/server/lifecycle.ts
@@ -4,6 +4,7 @@ import type {
   AgentPermissionResponse,
   AgentTimelineItem,
   AgentSessionConfig,
+  JsonValue,
 } from "@getpaseo/protocol/agent-types";
 import type { PaseoApi } from "@getpaseo/client";
 import type { WorkspaceCreateRequest } from "@getpaseo/protocol/messages";
@@ -19,6 +20,8 @@ export interface PluginHookWorkspace {
   cwd: string;
   name: string | null;
   archivedAt: string | null;
+  /** Data plugins stored on the workspace. Paseo never reads a key. */
+  metadata: Record<string, JsonValue>;
 }
 
 export interface PluginHookWorktree {
@@ -68,6 +71,8 @@ export interface PluginHookAgent {
   provider: string;
   cwd: string;
   title: string | null;
+  /** Data plugins stored on the agent. Paseo never reads a key. */
+  metadata: Record<string, JsonValue>;
 }
 
 export interface PluginSessionOpenRequest {
@@ -79,6 +84,7 @@ export interface PluginSessionOpenRequest {
   purpose: "interactive" | "history";
   readonly title: string | null;
   readonly labels: Readonly<Record<string, string>>;
+  readonly metadata: Readonly<Record<string, JsonValue>>;
   tools: AgentToolDefinition[];
   env: Record<string, string>;
   mcpServers: NonNullable<AgentSessionConfig["mcpServers"]>;
@@ -116,7 +122,12 @@ export interface PluginHookEvents {
 
 export interface PluginHookRequests {
   "worktree.create.before": PluginWorktreeCreateRequest;
-  "agent.create.before": { config: AgentSessionConfig; env?: Record<string, string> };
+  "agent.create.before": {
+    config: AgentSessionConfig;
+    env?: Record<string, string>;
+    /** Stored on the new agent. Always present in the payload; return it changed to change it. */
+    metadata?: Record<string, JsonValue>;
+  };
   "agent.open.before": PluginSessionOpenRequest;
   "workspace.create.before": Omit<WorkspaceCreateRequest, "type" | "requestId">;
 }
diff --git a/packages/protocol/src/messages.ts b/packages/protocol/src/messages.ts
index 30519993f2..439a271135 100644
--- a/packages/protocol/src/messages.ts
+++ b/packages/protocol/src/messages.ts
@@ -303,6 +303,9 @@ import type {
 // unknown avoids zod-aot's recursive z.json() object-codegen regression.
 const JsonWireValueSchema = z.unknown() as z.ZodType<JsonValue>;
 
+/** Plugin-owned data on an agent or workspace. Paseo stores it and never reads a key. */
+const EntityMetadataSchema = z.record(z.string(), JsonWireValueSchema);
+
 export const AgentStatusSchema = z.enum(AGENT_LIFECYCLE_STATUSES);
 
 const AgentModeSchema: z.ZodType<AgentMode> = z.object({
@@ -922,6 +925,7 @@ export const AgentSnapshotPayloadSchema = z.object({
   lastError: z.string().optional(),
   title: z.string().nullable(),
   labels: z.record(z.string(), z.string()).default({}),
+  metadata: EntityMetadataSchema.optional(),
   requiresAttention: z.boolean().optional(),
   attentionReason: z.enum(["finished", "error", "permission"]).nullable().optional(),
   attentionTimestamp: z.string().nullable().optional(),
@@ -1068,6 +1072,22 @@ export const WorkspaceTitleSetRequestSchema = z.object({
   requestId: z.string(),
 });
 
+export const AgentMetadataUpdateRequestSchema = z.object({
+  type: z.literal("agent.metadata.update.request"),
+  agentId: z.string(),
+  // Top-level keys replace; null removes the key.
+  patch: EntityMetadataSchema,
+  requestId: z.string(),
+});
+
+export const WorkspaceMetadataUpdateRequestSchema = z.object({
+  type: z.literal("workspace.metadata.update.request"),
+  workspaceId: z.string(),
+  // Top-level keys replace; null removes the key.
+  patch: EntityMetadataSchema,
+  requestId: z.string(),
+});
+
 export const WorkspacePinSetRequestSchema = z.object({
   type: z.literal("workspace.pin.set.request"),
   workspaceId: z.string(),
@@ -1826,6 +1846,7 @@ export const CreateAgentRequestMessageSchema = z.object({
   // Workspace creation intent, rejected when selecting an existing workspace.
   background: z.boolean().optional(),
   labels: z.record(z.string(), z.string()).default({}),
+  metadata: EntityMetadataSchema.optional(),
   requestId: z.string(),
 });
 
@@ -2204,6 +2225,28 @@ export const WorkspaceTitleSetResponseSchema = z.object({
   payload: WorkspaceTitleSetResponsePayloadSchema,
 });
 
+export const AgentMetadataUpdateResponseSchema = z.object({
+  type: z.literal("agent.metadata.update.response"),
+  payload: z.object({
+    requestId: z.string(),
+    agentId: z.string(),
+    accepted: z.boolean(),
+    metadata: EntityMetadataSchema.nullable(),
+    error: z.string().nullable(),
+  }),
+});
+
+export const WorkspaceMetadataUpdateResponseSchema = z.object({
+  type: z.literal("workspace.metadata.update.response"),
+  payload: z.object({
+    requestId: z.string(),
+    workspaceId: z.string(),
+    accepted: z.boolean(),
+    metadata: EntityMetadataSchema.nullable(),
+    error: z.string().nullable(),
+  }),
+});
+
 export const WorkspacePinSetResponsePayloadSchema = z.object({
   requestId: z.string(),
   workspaceId: z.string(),
@@ -2759,6 +2802,7 @@ export const WorkspaceCreateRequestSchema = z.object({
   idempotencyKey: z.string().min(1).max(512).optional(),
   // Optional user-set title applied to the created workspace.
   title: z.string().optional(),
+  metadata: EntityMetadataSchema.optional(),
   // Optional prompt context for workspace-level name/branch generation.
   firstAgentContext: FirstAgentContextSchema.optional(),
   // Retained for wire parsing; public internal creation is no longer supported.
@@ -3355,6 +3399,8 @@ export const SessionInboundMessageSchema = z.discriminatedUnion("type", [
   ProjectIconSetRequestSchema,
   ProjectRemoveRequestSchema,
   WorkspaceTitleSetRequestSchema,
+  AgentMetadataUpdateRequestSchema,
+  WorkspaceMetadataUpdateRequestSchema,
   WorkspacePinSetRequestSchema,
   WorkspaceLabelListRequestSchema,
   WorkspaceLabelAssignmentSetRequestSchema,
@@ -3888,6 +3934,7 @@ export const ServerInfoStatusPayloadSchema = z
         explicitEventSubscriptions: z.boolean().optional(),
         ownedSubscriptions: z.boolean().optional(),
         providerOptionControls: z.boolean().optional(),
+        entityMetadata: z.boolean().optional(),
         binaryChunkingV1: z.boolean().optional(),
         workspaceSetupObservation: z.boolean().optional(),
         workspaceSortTimes: z.boolean().optional(),
@@ -4222,6 +4269,7 @@ export const WorkspaceDescriptorPayloadSchema = z
     pinnedAt: z.string().nullable().optional(),
     // COMPAT(workspaceLabels): added in v0.5.0, remove optional after 2027-08-14.
     labels: z.array(z.string()).optional(),
+    metadata: EntityMetadataSchema.optional(),
     // Retained for wire parsing of older daemon descriptors.
     internal: z.boolean().optional(),
     background: z.boolean().optional(),
@@ -7200,6 +7248,8 @@ export const SessionOutboundMessageSchema = z.discriminatedUnion("type", [
   ProjectIconSetResponseSchema,
   ProjectRemoveResponseSchema,
   WorkspaceTitleSetResponseSchema,
+  AgentMetadataUpdateResponseSchema,
+  WorkspaceMetadataUpdateResponseSchema,
   WorkspacePinSetResponseSchema,
   WorkspaceRecoveryInspectResponseSchema,
   WorkspaceRecoveryRestoreResponseSchema,
@@ -7566,6 +7616,10 @@ export type ProjectIconSetRequest = z.infer<typeof ProjectIconSetRequestSchema>;
 export type ProjectRemoveRequest = z.infer<typeof ProjectRemoveRequestSchema>;
 export type WorkspaceTitleSetRequest = z.infer<typeof WorkspaceTitleSetRequestSchema>;
 export type WorkspacePinSetRequest = z.infer<typeof WorkspacePinSetRequestSchema>;
+export type AgentMetadataUpdateRequest = z.infer<typeof AgentMetadataUpdateRequestSchema>;
+export type WorkspaceMetadataUpdateRequest = z.infer<typeof WorkspaceMetadataUpdateRequestSchema>;
+export type AgentMetadataUpdateResponse = z.infer<typeof AgentMetadataUpdateResponseSchema>;
+export type WorkspaceMetadataUpdateResponse = z.infer<typeof WorkspaceMetadataUpdateResponseSchema>;
 export type WorkspaceRecoveryInspectRequest = z.infer<typeof WorkspaceRecoveryInspectRequestSchema>;
 export type WorkspaceRecoveryRestoreRequest = z.infer<typeof WorkspaceRecoveryRestoreRequestSchema>;
 export type SetAgentModeRequestMessage = z.infer<typeof SetAgentModeRequestMessageSchema>;
diff --git a/packages/server/src/server/agent/agent-loading.ts b/packages/server/src/server/agent/agent-loading.ts
index ba444a394d..e9eb56fe0e 100644
--- a/packages/server/src/server/agent/agent-loading.ts
+++ b/packages/server/src/server/agent/agent-loading.ts
@@ -133,6 +133,7 @@ export async function ensureAgentLoaded(
       }
       snapshot = await deps.agentManager.createAgent(config, agentId, {
         labels: record.labels,
+        metadata: record.metadata,
         workspaceId: record.workspaceId,
         owner: record.owner,
         env: record.launchEnv,
diff --git a/packages/server/src/server/agent/agent-manager.test.ts b/packages/server/src/server/agent/agent-manager.test.ts
index a630d58d2a..063f4da855 100644
--- a/packages/server/src/server/agent/agent-manager.test.ts
+++ b/packages/server/src/server/agent/agent-manager.test.ts
@@ -12475,6 +12475,7 @@ test.each([
               provider: "codex",
               cwd: workdir,
               title: null,
+              metadata: {},
             },
             turnId: "hook-turn",
             outcome,
diff --git a/packages/server/src/server/agent/agent-manager.ts b/packages/server/src/server/agent/agent-manager.ts
index ce4cabaef6..2814d80f0f 100644
--- a/packages/server/src/server/agent/agent-manager.ts
+++ b/packages/server/src/server/agent/agent-manager.ts
@@ -6,6 +6,7 @@ import { ensureAgentLoaded } from "./agent-loading.js";
 import { projectTimelineRows } from "./timeline-projection.js";
 import type { PluginLifecycle } from "../plugins/lifecycle/index.js";
 import { describeHookAgent, publishAgentStream } from "../plugins/lifecycle/index.js";
+import { applyRecordPatch } from "../record-patch.js";
 import type { PluginSessionOpenRequest } from "@getpaseo/plugin/server";
 import { randomUUID } from "node:crypto";
 import { basename, resolve } from "node:path";
@@ -60,7 +61,7 @@ import {
   type ListImportableSessionsOptions,
 } from "./agent-sdk-types.js";
 import { buildArchivedAgentRecord, type ArchivedStoredAgentRecord } from "./agent-archive.js";
-import type { ProviderOptions } from "@getpaseo/protocol/agent-types";
+import type { JsonValue, ProviderOptions } from "@getpaseo/protocol/agent-types";
 import { toStoredAgentRecord } from "./agent-projections.js";
 import {
   applyProviderOptionsPatch,
@@ -324,6 +325,7 @@ type ProviderClientMap = Partial<Record<AgentProvider, AgentClient>>;
 
 export interface CreateAgentOptions {
   labels?: Record<string, string>;
+  metadata?: AgentMetadata;
   initialPrompt?: string;
   env?: Record<string, string>;
   persistSession?: boolean;
@@ -465,6 +467,8 @@ interface ManagedAgentBase {
    * User-defined labels for categorizing agents (e.g., { surface: "workspace" }).
    */
   labels: Record<string, string>;
+  /** Plugin-owned data. Paseo persists and forwards it and never reads a key. */
+  metadata: AgentMetadata;
 }
 
 type ManagedAgentWithSession = ManagedAgentBase & {
@@ -524,6 +528,7 @@ type ActiveManagedAgent =
 
 type LiveManagedAgent = ActiveManagedAgent;
 type AgentLabelPatch = Record<string, string | null>;
+type AgentMetadata = Record<string, JsonValue>;
 
 function attachManagedTurnIdentity(
   agent: ActiveManagedAgent,
@@ -571,6 +576,7 @@ interface WriteLabelsResult {
 interface AgentMetadataPatch {
   title?: string;
   labels?: AgentLabelPatch;
+  metadata?: Record<string, JsonValue | null>;
 }
 
 const SYSTEM_ERROR_PREFIX = "[System Error]";
@@ -629,6 +635,11 @@ function createAbortError(signal: AbortSignal | undefined, fallbackMessage: stri
   return Object.assign(new Error(message), { name: "AbortError" });
 }
 
+/** The user labels and plugin metadata an agent carries; both default to empty. */
+function agentEntityData(source?: { labels?: Record<string, string>; metadata?: AgentMetadata }) {
+  return { labels: source?.labels ?? {}, metadata: source?.metadata ?? {} };
+}
+
 function validateAgentId(agentId: string, source: string): string {
   const result = AgentIdSchema.safeParse(agentId);
   if (!result.success) {
@@ -637,21 +648,6 @@ function validateAgentId(agentId: string, source: string): string {
   return result.data;
 }
 
-function applyLabelPatch(
-  labels: Record<string, string>,
-  patch: AgentLabelPatch,
-): Record<string, string> {
-  const nextLabels = { ...labels };
-  for (const [key, value] of Object.entries(patch)) {
-    if (value === null) {
-      delete nextLabels[key];
-    } else {
-      nextLabels[key] = value;
-    }
-  }
-  return nextLabels;
-}
-
 function buildExplicitTimelineSeedForRegister(
   now: Date,
   options:
@@ -1386,6 +1382,7 @@ export class AgentManager {
       const request = await this.pluginLifecycle.before("agent.create.before", {
         config: sent,
         env: options.env,
+        metadata: options.metadata ?? {},
       });
       // COMPAT(featureValues): added in v0.15.0, remove after 2027-05-01. A plugin written
       // against the previous SDK edits `config.featureValues`.
@@ -1397,7 +1394,7 @@ export class AgentManager {
         }),
         internal: config.internal,
       };
-      options = { ...options, env: request.env };
+      options = { ...options, env: request.env, metadata: request.metadata ?? options.metadata };
     }
     await this.deleteAgentState(resolvedAgentId);
     const { storedConfig, launchConfig, paseoToolPolicy } = await this.prepareSessionConfig(
@@ -1422,6 +1419,7 @@ export class AgentManager {
         workspaceId: options.workspaceId ?? null,
         title: options.initialTitle ?? storedConfig.title ?? null,
         labels: options.labels ?? {},
+        metadata: options.metadata ?? {},
       },
     );
     const providerLaunchConfig = this.resolveProviderLaunchConfig(launchConfig, launchContext);
@@ -1432,6 +1430,7 @@ export class AgentManager {
     const agent = await this.registerSession(session, storedConfig, resolvedAgentId, {
       launchedOptions,
       labels: options.labels,
+      metadata: options.metadata,
       initialTitle: options.initialTitle,
       workspaceId: options.workspaceId,
       owner: options.owner,
@@ -1465,6 +1464,7 @@ export class AgentManager {
       updatedAt?: Date;
       lastUserMessageAt?: Date | null;
       labels?: Record<string, string>;
+      metadata?: AgentMetadata;
       workspaceId?: string;
       owner?: AgentOwner;
       attention?: AttentionState;
@@ -1497,6 +1497,7 @@ export class AgentManager {
       updatedAt?: Date;
       lastUserMessageAt?: Date | null;
       labels?: Record<string, string>;
+      metadata?: AgentMetadata;
       workspaceId?: string;
       owner?: AgentOwner;
       attention?: AttentionState;
@@ -1549,7 +1550,7 @@ export class AgentManager {
         purpose,
         workspaceId: options?.workspaceId ?? null,
         title: record?.title ?? mergedConfig.title ?? null,
-        labels: record?.labels ?? options?.labels ?? {},
+        ...agentEntityData(record ?? options),
       },
     );
     const providerLaunchConfig = this.resolveProviderLaunchConfig(launchConfig, launchContext);
@@ -1720,6 +1721,7 @@ export class AgentManager {
         workspaceId: existing.workspaceId,
         title: await this.resolveInitialPersistedTitle(agentId, existing.config, null),
         labels: existing.labels,
+        metadata: existing.metadata,
       },
     );
     const providerLaunchConfig = this.resolveProviderLaunchConfig(launchConfig, launchContext);
@@ -1764,6 +1766,7 @@ export class AgentManager {
       return this.registerSession(session, storedConfig, agentId, {
         launchedOptions,
         labels: existing.labels,
+        metadata: existing.metadata,
         workspaceId: existing.workspaceId,
         owner: existing.owner,
         launchEnv: existing.launchEnv,
@@ -2224,6 +2227,7 @@ export class AgentManager {
         attention,
         internal: record.internal,
         labels: record.labels,
+        metadata: record.metadata,
       },
     });
   }
@@ -2425,10 +2429,30 @@ export class AgentManager {
     });
   }
 
+  /** Applies a plugin-metadata patch (null removes a key) and returns the stored result. */
+  async setMetadata(
+    agentId: string,
+    patch: Record<string, JsonValue | null>,
+  ): Promise<AgentMetadata> {
+    return this.runLifecycleMutation(agentId, async () => {
+      const liveAgent = this.agents.get(agentId);
+      if (liveAgent) {
+        liveAgent.metadata = applyRecordPatch<JsonValue>(liveAgent.metadata, patch);
+        this.touchUpdatedAt(liveAgent);
+        await this.persistSnapshot(liveAgent);
+        this.emitState(liveAgent, { persist: false });
+        return liveAgent.metadata;
+      }
+      const record = await this.writeStoredMetadata(agentId, { metadata: patch });
+      if (!record.internal) this.dispatchStoredAgentState(record);
+      return record.metadata;
+    });
+  }
+
   private async writeLabels(agentId: string, patch: AgentLabelPatch): Promise<WriteLabelsResult> {
     const liveAgent = this.agents.get(agentId);
     if (liveAgent) {
-      liveAgent.labels = applyLabelPatch(liveAgent.labels, patch);
+      liveAgent.labels = applyRecordPatch(liveAgent.labels, patch);
       this.touchUpdatedAt(liveAgent);
       await this.persistSnapshot(liveAgent);
       this.emitState(liveAgent, { persist: false });
@@ -2453,7 +2477,8 @@ export class AgentManager {
     const nextRecord = {
       ...record,
       ...(patch.title ? { title: patch.title } : {}),
-      ...(patch.labels ? { labels: applyLabelPatch(record.labels, patch.labels) } : {}),
+      ...(patch.labels ? { labels: applyRecordPatch(record.labels, patch.labels) } : {}),
+      ...(patch.metadata ? { metadata: applyRecordPatch(record.metadata, patch.metadata) } : {}),
       updatedAt: this.nextStoredUpdatedAt(record),
     };
     await registry.upsert(nextRecord);
@@ -2632,7 +2657,7 @@ export class AgentManager {
     await registry.upsert({
       ...record,
       ...(updates?.workspaceId ? { workspaceId: updates.workspaceId } : {}),
-      ...(updates?.labels ? { labels: applyLabelPatch(record.labels, updates.labels) } : {}),
+      ...(updates?.labels ? { labels: applyRecordPatch(record.labels, updates.labels) } : {}),
       archivedAt: null,
       updatedAt: new Date().toISOString(),
     });
@@ -3919,6 +3944,7 @@ export class AgentManager {
       updatedAt?: Date;
       lastUserMessageAt?: Date | null;
       labels?: Record<string, string>;
+      metadata?: AgentMetadata;
       timeline?: AgentTimelineItem[];
       timelineRows?: AgentTimelineRow[];
       timelineNextSeq?: number;
@@ -4128,6 +4154,7 @@ export class AgentManager {
           updatedAt?: Date;
           lastUserMessageAt?: Date | null;
           labels?: Record<string, string>;
+          metadata?: AgentMetadata;
           historyPrimed?: boolean;
           lastUsage?: AgentUsage;
           lastError?: string;
@@ -4186,7 +4213,7 @@ export class AgentManager {
       lastError: options?.lastError,
       attention: resolveInitialAttention(options?.attention),
       internal: config.internal ?? false,
-      labels: options?.labels ?? {},
+      ...agentEntityData(options),
     } as ActiveManagedAgent;
   }
 
@@ -5770,6 +5797,7 @@ export class AgentManager {
       workspaceId?: string | null;
       title?: string | null;
       labels?: Record<string, string>;
+      metadata?: AgentMetadata;
     },
   ): Promise<AgentLaunchContext> {
     // A plugin changing during this open must still make the resulting session stale.
@@ -5787,7 +5815,7 @@ export class AgentManager {
         purpose: opening?.purpose ?? "interactive",
         env: { ...env },
         title: opening?.title ?? null,
-        labels: opening?.labels ?? {},
+        ...agentEntityData(opening),
         tools: [],
         mcpServers: {},
       };
diff --git a/packages/server/src/server/agent/agent-projections.ts b/packages/server/src/server/agent/agent-projections.ts
index c727a045b3..47d2052414 100644
--- a/packages/server/src/server/agent/agent-projections.ts
+++ b/packages/server/src/server/agent/agent-projections.ts
@@ -94,6 +94,7 @@ export function toStoredAgentRecord(
     lastUserMessageAt: agent.lastUserMessageAt ? agent.lastUserMessageAt.toISOString() : null,
     title: options?.title ?? null,
     labels: agent.labels,
+    metadata: agent.metadata,
     lastStatus: agent.lifecycle,
     lastModeId: agent.currentModeId ?? config?.modeId ?? null,
     config: config ?? null,
@@ -155,6 +156,7 @@ export function toAgentPayload(
     persistence: projectPersistenceHandleForWire(agent.persistence),
     title: options?.title ?? null,
     labels: agent.labels,
+    metadata: agent.metadata,
     archivedAt: options?.archivedAt ?? null,
     ...(agent.internal ? { internal: true } : {}),
   };
@@ -284,6 +286,7 @@ export function buildStoredAgentPayload(
     archivedAt: record.archivedAt ?? null,
     ...(record.internal ? { internal: true } : {}),
     labels: normalizeLabels(record.labels),
+    metadata: record.metadata,
     ...(typeof record.lastError === "string" ? { lastError: record.lastError } : {}),
     ...(providerAvailable ? {} : { providerUnavailable: true }),
   };
diff --git a/packages/server/src/server/agent/agent-storage.ts b/packages/server/src/server/agent/agent-storage.ts
index 03c99cfb0b..2ffdceb923 100644
--- a/packages/server/src/server/agent/agent-storage.ts
+++ b/packages/server/src/server/agent/agent-storage.ts
@@ -2,6 +2,7 @@ import { promises as fs, type Dirent } from "node:fs";
 import path from "node:path";
 import { z } from "zod";
 import type { Logger } from "pino";
+import type { JsonValue } from "@getpaseo/protocol/agent-types";
 
 import { writeJsonFileAtomic } from "../atomic-file.js";
 import { AgentFeatureSchema, AgentOptionControlSchema, AgentStatusSchema } from "../messages.js";
@@ -56,6 +57,7 @@ const RAW_STORED_AGENT_SCHEMA = z.object({
   lastUserMessageAt: z.string().nullable().optional(),
   title: z.string().nullable().optional(),
   labels: z.record(z.string(), z.string()).default({}),
+  metadata: z.record(z.string(), z.custom<JsonValue>()).default({}),
   lastStatus: AgentStatusSchema.default("closed"),
   resumeOnStartup: z.boolean().optional(),
   lastModeId: z.string().nullable().optional(),
diff --git a/packages/server/src/server/agent/create-agent/create.ts b/packages/server/src/server/agent/create-agent/create.ts
index 3e47eb0978..d8dc3f3884 100644
--- a/packages/server/src/server/agent/create-agent/create.ts
+++ b/packages/server/src/server/agent/create-agent/create.ts
@@ -59,6 +59,7 @@ export interface CreateAgentFromSessionInput {
   images?: Array<{ data: string; mimeType: string }>;
   attachments?: AgentAttachment[];
   labels: Record<string, string>;
+  metadata?: CreateAgentOptions["metadata"];
   env?: Record<string, string>;
   provisionalTitle: string | null;
   firstAgentContext: FirstAgentContext;
@@ -251,6 +252,7 @@ async function resolveSessionCreateAgent(
     config: sessionConfig,
     createOptions: {
       labels: input.labels,
+      metadata: input.metadata,
       initialPrompt: trimmedPrompt,
       env: input.env,
       initialTitle: input.provisionalTitle,
diff --git a/packages/server/src/server/authorization/operation-permissions.ts b/packages/server/src/server/authorization/operation-permissions.ts
index c972771bf8..3fd4e153dc 100644
--- a/packages/server/src/server/authorization/operation-permissions.ts
+++ b/packages/server/src/server/authorization/operation-permissions.ts
@@ -214,6 +214,8 @@ const INBOUND_PERMISSION = {
   "workspace.label.delete.request": "workspace.manage",
   "workspace.label.list.request": "workspace.read",
   "workspace.label.update.request": "workspace.manage",
+  "agent.metadata.update.request": "workspace.write",
+  "workspace.metadata.update.request": "workspace.manage",
   "workspace.pin.set.request": "workspace.manage",
   "workspace.recovery.inspect.request": ["workspace.read", "hub.execute"],
   "workspace.recovery.restore.request": ["workspace.manage", "hub.execute"],
@@ -453,6 +455,8 @@ const OUTBOUND_PERMISSION = {
   "workspace.label.list.response": "workspace.read",
   "workspace.label.update": "workspace.read",
   "workspace.label.update.response": "workspace.manage",
+  "agent.metadata.update.response": "workspace.write",
+  "workspace.metadata.update.response": "workspace.manage",
   "workspace.pin.set.response": "workspace.manage",
   "workspace.recovery.inspect.response": ["workspace.read", "hub.execute"],
   "workspace.recovery.restore.response": ["workspace.manage", "hub.execute"],
diff --git a/packages/server/src/server/paseo-worktree-service.ts b/packages/server/src/server/paseo-worktree-service.ts
index 1205554d4a..322e8704ab 100644
--- a/packages/server/src/server/paseo-worktree-service.ts
+++ b/packages/server/src/server/paseo-worktree-service.ts
@@ -1,3 +1,4 @@
+import type { JsonValue } from "@getpaseo/protocol/agent-types";
 import type { PluginLifecycle } from "./plugins/lifecycle/index.js";
 import { stat } from "node:fs/promises";
 import { resolve } from "node:path";
@@ -34,6 +35,7 @@ export interface CreatePaseoWorktreeInput extends CreateWorktreeCoreInput {
   workspaceId?: string;
   projectId?: string;
   title?: string;
+  metadata?: Record<string, JsonValue>;
   background?: boolean;
   callerWorkspaceId?: string;
 }
@@ -113,6 +115,7 @@ async function createPaseoWorktreeWithPriority(
       branch: createdWorktree.worktree.branchName || null,
       baseBranch: createdWorktree.worktree.comparisonBaseRef,
       title: input.title?.trim() || resolveFirstAgentPromptTitle(input.firstAgentContext),
+      metadata: input.metadata,
       expectsInitialAgent: Boolean(input.firstAgentContext),
       background: input.background,
       callerWorkspaceId: input.callerWorkspaceId,
diff --git a/packages/server/src/server/persistence-hooks.ts b/packages/server/src/server/persistence-hooks.ts
index 31d8c45ed0..fe235c3f9c 100644
--- a/packages/server/src/server/persistence-hooks.ts
+++ b/packages/server/src/server/persistence-hooks.ts
@@ -137,6 +137,7 @@ export function extractTimestamps(record: StoredAgentRecord): {
   updatedAt: Date;
   lastUserMessageAt: Date | null;
   labels?: Record<string, string>;
+  metadata?: StoredAgentRecord["metadata"];
   workspaceId?: string;
   owner?: StoredAgentRecord["owner"];
 } {
@@ -145,6 +146,7 @@ export function extractTimestamps(record: StoredAgentRecord): {
     updatedAt: new Date(resolveStoredAgentUpdatedAt(record)),
     lastUserMessageAt: record.lastUserMessageAt ? new Date(record.lastUserMessageAt) : null,
     labels: record.labels,
+    metadata: record.metadata,
     workspaceId: record.workspaceId,
     owner: record.owner,
   };
diff --git a/packages/server/src/server/plugins/lifecycle.e2e.test.ts b/packages/server/src/server/plugins/lifecycle.e2e.test.ts
index bd1dfa8859..951d59b5fa 100644
--- a/packages/server/src/server/plugins/lifecycle.e2e.test.ts
+++ b/packages/server/src/server/plugins/lifecycle.e2e.test.ts
@@ -240,6 +240,149 @@ export default function contribute(server) {
   }
 }, 60_000);
 
+test("metadata set at creation reaches the hooks, a before hook can add to it, and snapshots carry it", async () => {
+  const directory = await mkdtemp(path.join(tmpdir(), "paseo-metadata-hooks-"));
+  const daemon = await createTestPaseoDaemon();
+  const client = new DaemonClient({ url: `ws://127.0.0.1:${daemon.port}/ws` });
+  try {
+    await writeFile(
+      path.join(directory, "paseo-plugin.json"),
+      JSON.stringify({
+        id: "metadata-hooks",
+        requirements: { paseo: `>=${resolveDaemonVersion(import.meta.url)}` },
+      }),
+    );
+    await writeFile(
+      path.join(directory, "index.server.ts"),
+      `
+export default function contribute(server) {
+  const log = (hook, metadata) => console.log(JSON.stringify({ hook, metadata }));
+  server.addHook("workspace.create.before", async ({ request }) => {
+    log("workspace.create.before", request.metadata);
+    return request;
+  });
+  server.addHook("workspace.create.after", async ({ workspace }) => {
+    log("workspace.create.after", workspace.metadata);
+  });
+  server.addHook("agent.create.before", async ({ request }) => {
+    log("agent.create.before", request.metadata);
+    return { ...request, metadata: { ...request.metadata, "hook.added": true } };
+  });
+  server.addHook("agent.open.before", async ({ request }) => {
+    log("agent.open.before", request.metadata);
+    return request;
+  });
+  server.addHook("agent.create.after", async ({ agent }) => {
+    log("agent.create.after", agent.metadata);
+  });
+  return () => {};
+}
+`,
+    );
+    await client.connect();
+    await client.fetchAgents({ subscribe: {} });
+    await client.patchDaemonConfig({ pluginsEnabled: true });
+    await client.installDirectoryPlugin(directory);
+    const workspace = await client.createWorkspace({
+      source: { kind: "directory", path: directory },
+      metadata: { "linear.issue": { id: "ENG-123" } },
+    });
+    expect(workspace.workspace?.metadata).toEqual({ "linear.issue": { id: "ENG-123" } });
+    const agent = await client.createAgent({
+      provider: "claude",
+      cwd: directory,
+      workspaceId: workspace.workspace!.id,
+      metadata: { "linear.issue": { id: "ENG-123" } },
+    });
+    expect(agent.metadata).toEqual({ "linear.issue": { id: "ENG-123" }, "hook.added": true });
+    await expect
+      .poll(async () => {
+        const logs = await client.getPluginLogs("metadata-hooks");
+        return logs
+          .filter((entry) => entry.message.startsWith('{"hook":'))
+          .map((entry) => JSON.parse(entry.message));
+      })
+      .toMatchObject([
+        { hook: "workspace.create.before", metadata: { "linear.issue": { id: "ENG-123" } } },
+        { hook: "workspace.create.after", metadata: { "linear.issue": { id: "ENG-123" } } },
+        { hook: "agent.create.before", metadata: { "linear.issue": { id: "ENG-123" } } },
+        {
+          hook: "agent.open.before",
+          metadata: { "linear.issue": { id: "ENG-123" }, "hook.added": true },
+        },
+        {
+          hook: "agent.create.after",
+          metadata: { "linear.issue": { id: "ENG-123" }, "hook.added": true },
+        },
+      ]);
+  } finally {
+    await client.close();
+    await daemon.close();
+    await rm(directory, { recursive: true, force: true });
+  }
+}, 60_000);
+
+test("metadata set at creation and through setMetadata survives a daemon restart", async () => {
+  const root = await mkdtemp(path.join(tmpdir(), "paseo-metadata-restart-"));
+  const directory = await mkdtemp(path.join(tmpdir(), "paseo-metadata-cwd-"));
+  try {
+    const first = await createTestPaseoDaemon({ paseoHomeRoot: root, cleanup: false });
+    const firstClient = new DaemonClient({ url: `ws://127.0.0.1:${first.port}/ws` });
+    let agentId: string;
+    let workspaceId: string;
+    try {
+      await firstClient.connect();
+      await firstClient.fetchAgents({ subscribe: {} });
+      const workspace = await firstClient.createWorkspace({
+        source: { kind: "directory", path: directory },
+        metadata: { "a.workspace": 1, "b.workspace": "to remove" },
+      });
+      workspaceId = workspace.workspace!.id;
+      const agent = await firstClient.createAgent({
+        provider: "claude",
+        cwd: directory,
+        workspaceId,
+        metadata: { "a.agent": { nested: [1, 2] }, "b.agent": "to remove" },
+      });
+      agentId = agent.id;
+      expect(
+        await firstClient.setAgentMetadata(agentId, { "b.agent": null, "c.agent": true }),
+      ).toEqual({
+        "a.agent": { nested: [1, 2] },
+        "c.agent": true,
+      });
+      expect(
+        await firstClient.setWorkspaceMetadata(workspaceId, {
+          "b.workspace": null,
+          "c.workspace": [],
+        }),
+      ).toEqual({ "a.workspace": 1, "c.workspace": [] });
+    } finally {
+      await firstClient.close();
+      await first.close();
+    }
+
+    const second = await createTestPaseoDaemon({ paseoHomeRoot: root, cleanup: false });
+    const secondClient = new DaemonClient({ url: `ws://127.0.0.1:${second.port}/ws` });
+    try {
+      await secondClient.connect();
+      const agent = await secondClient.fetchAgent({ agentId });
+      expect(agent?.agent.metadata).toEqual({ "a.agent": { nested: [1, 2] }, "c.agent": true });
+      const workspaces = await secondClient.fetchWorkspaces({});
+      expect(workspaces.entries.find((entry) => entry.id === workspaceId)?.metadata).toEqual({
+        "a.workspace": 1,
+        "c.workspace": [],
+      });
+    } finally {
+      await secondClient.close();
+      await second.close();
+    }
+  } finally {
+    await rm(root, { recursive: true, force: true });
+    await rm(directory, { recursive: true, force: true });
+  }
+}, 60_000);
+
 test("agent creation hooks change the provider and environment before the session opens", async () => {
   const directory = await mkdtemp(path.join(tmpdir(), "paseo-agent-hooks-"));
   const pluginDirectory = await createProviderPlugin(directory, {
diff --git a/packages/server/src/server/plugins/lifecycle/handlers.test.ts b/packages/server/src/server/plugins/lifecycle/handlers.test.ts
index e17cca1ed5..8c57598f92 100644
--- a/packages/server/src/server/plugins/lifecycle/handlers.test.ts
+++ b/packages/server/src/server/plugins/lifecycle/handlers.test.ts
@@ -92,6 +92,7 @@ test("session-open hooks reject changes to session identity instead of silently
         env: {},
         title: null,
         labels: {},
+        metadata: {},
         tools: [],
         mcpServers: {},
       },
@@ -116,6 +117,7 @@ test.each([{ title: "Changed" }, { labels: { changed: "true" } }])(
           cwd: "/project",
           title: "Original",
           labels: {},
+          metadata: {},
           tools: [],
           mcpServers: {},
           env: {},
diff --git a/packages/server/src/server/plugins/lifecycle/index.ts b/packages/server/src/server/plugins/lifecycle/index.ts
index d4f58cc78c..a55b61f6d6 100644
--- a/packages/server/src/server/plugins/lifecycle/index.ts
+++ b/packages/server/src/server/plugins/lifecycle/index.ts
@@ -13,6 +13,7 @@ import {
 import type { AgentToolDefinition } from "@getpaseo/plugin/server";
 import type { AgentStreamEvent } from "../../agent/agent-sdk-types.js";
 import { z } from "zod";
+import type { JsonValue } from "@getpaseo/protocol/agent-types";
 import { CreateAgentRequestMessageSchema } from "@getpaseo/protocol/messages";
 import type {
   PluginHookAgent,
@@ -91,6 +92,7 @@ const beforeSchemas = {
   "agent.create.before": CreateAgentRequestMessageSchema.pick({
     config: true,
     env: true,
+    metadata: true,
   }).strict(),
   "agent.open.before": z
     .object({
@@ -102,6 +104,7 @@ const beforeSchemas = {
       purpose: z.enum(["interactive", "history"]),
       title: z.string().nullable(),
       labels: z.record(z.string(), z.string()),
+      metadata: z.record(z.string(), z.custom<JsonValue>()),
       tools: z.array(agentToolMetadataSchema),
       env: z.record(z.string(), z.string()),
       mcpServers: CreateAgentRequestMessageSchema.shape.config.shape.mcpServers.unwrap(),
@@ -152,6 +155,7 @@ export function describeHookWorkspace(workspace: PersistedWorkspaceRecord): Plug
     cwd: workspace.cwd,
     name: workspace.title,
     archivedAt: workspace.archivedAt,
+    metadata: workspace.metadata,
   };
 }
 
@@ -162,6 +166,7 @@ export function describeHookAgent(agent: {
   cwd: string;
   title?: string | null;
   labels: Record<string, string>;
+  metadata: Record<string, JsonValue>;
 }): PluginHookAgent {
   return {
     id: agent.id,
@@ -170,6 +175,7 @@ export function describeHookAgent(agent: {
     provider: agent.provider,
     cwd: agent.cwd,
     title: agent.title ?? null,
+    metadata: agent.metadata,
   };
 }
 
@@ -229,7 +235,8 @@ export async function validateBeforeResult<Name extends keyof PluginWireBeforeRe
       previous.reason !== next.reason ||
       previous.purpose !== next.purpose ||
       previous.title !== next.title ||
-      !isDeepStrictEqual(previous.labels, next.labels)
+      !isDeepStrictEqual(previous.labels, next.labels) ||
+      !isDeepStrictEqual(previous.metadata, next.metadata)
     ) {
       throw new Error("agent.open.before hooks can only change env, tools, and mcpServers");
     }
diff --git a/packages/server/src/server/plugins/plugin-process-protocol.ts b/packages/server/src/server/plugins/plugin-process-protocol.ts
index e582387d48..228c690af1 100644
--- a/packages/server/src/server/plugins/plugin-process-protocol.ts
+++ b/packages/server/src/server/plugins/plugin-process-protocol.ts
@@ -1,3 +1,4 @@
+import type { JsonValue } from "@getpaseo/protocol/agent-types";
 import type { PluginHookAgent } from "@getpaseo/plugin/server";
 import { UsageScopeSchema, type UsageScope } from "@getpaseo/plugin/server/usage";
 import type {
@@ -157,6 +158,7 @@ export const PluginProcessRequestSchema: z.ZodType<PluginProcessRequest> = z.dis
             provider: z.string(),
             cwd: z.string(),
             title: z.string().nullable(),
+            metadata: z.record(z.string(), z.custom<JsonValue>()),
           })
           .strict(),
         name: z.string(),
diff --git a/packages/server/src/server/record-patch.ts b/packages/server/src/server/record-patch.ts
new file mode 100644
index 0000000000..490ad0b6b0
--- /dev/null
+++ b/packages/server/src/server/record-patch.ts
@@ -0,0 +1,15 @@
+/** Top-level keys replace; a null value removes the key. */
+export function applyRecordPatch<Value>(
+  record: Record<string, Value>,
+  patch: Record<string, Value | null>,
+): Record<string, Value> {
+  const next = { ...record };
+  for (const [key, value] of Object.entries(patch)) {
+    if (value === null) {
+      delete next[key];
+    } else {
+      next[key] = value;
+    }
+  }
+  return next;
+}
diff --git a/packages/server/src/server/session.ts b/packages/server/src/server/session.ts
index 7c4f3405a2..7817694386 100644
--- a/packages/server/src/server/session.ts
+++ b/packages/server/src/server/session.ts
@@ -85,6 +85,7 @@ import { releaseWorkspaceServicePortPlan } from "./workspace-service-port-regist
 import { getErrorMessage, getErrorMessageOr } from "@getpaseo/protocol/error-utils";
 import { getAgentStatusPriority } from "@getpaseo/protocol/agent-state-bucket";
 import { getParentAgentIdFromLabels } from "@getpaseo/protocol/agent-labels";
+import { applyRecordPatch } from "./record-patch.js";
 import type { WorkspaceGitRuntimeSnapshot, WorkspaceGitService } from "./workspace-git-service.js";
 import type { ProjectUpdate } from "./workspace-reconciliation-service.js";
 import {
@@ -3093,6 +3094,10 @@ export class Session {
         return this.handleWorkspaceTitleSetRequest(msg.workspaceId, msg.title, msg.requestId);
       case "workspace.pin.set.request":
         return this.handleWorkspacePinSetRequest(msg.workspaceId, msg.pinned, msg.requestId);
+      case "agent.metadata.update.request":
+        return this.handleAgentMetadataUpdateRequest(msg);
+      case "workspace.metadata.update.request":
+        return this.handleWorkspaceMetadataUpdateRequest(msg);
       default:
         return undefined;
     }
@@ -3942,6 +3947,79 @@ export class Session {
     }
   }
 
+  private async handleAgentMetadataUpdateRequest(
+    request: Extract<SessionInboundMessage, { type: "agent.metadata.update.request" }>,
+  ): Promise<void> {
+    const { agentId, patch, requestId } = request;
+    this.sessionLogger.info({ agentId, requestId }, "session: agent.metadata.update.request");
+    try {
+      const metadata = await this.agentManager.setMetadata(agentId, patch);
+      this.emit({
+        type: "agent.metadata.update.response",
+        payload: { requestId, agentId, accepted: true, metadata, error: null },
+      });
+    } catch (error) {
+      this.sessionLogger.error(
+        { err: error, agentId, requestId },
+        "session: agent.metadata.update.request error",
+      );
+      this.emit({
+        type: "agent.metadata.update.response",
+        payload: {
+          requestId,
+          agentId,
+          accepted: false,
+          metadata: null,
+          error: getErrorMessageOr(error, "Failed to update agent metadata"),
+        },
+      });
+    }
+  }
+
+  private async handleWorkspaceMetadataUpdateRequest(
+    request: Extract<SessionInboundMessage, { type: "workspace.metadata.update.request" }>,
+  ): Promise<void> {
+    const { workspaceId, patch, requestId } = request;
+    this.sessionLogger.info(
+      { workspaceId, requestId },
+      "session: workspace.metadata.update.request",
+    );
+    const reject = (error: string) =>
+      this.emit({
+        type: "workspace.metadata.update.response",
+        payload: { requestId, workspaceId, accepted: false, metadata: null, error },
+      });
+    try {
+      const updatedAt = new Date().toISOString();
+      const updated = await this.workspaceRegistry.update(workspaceId, (existing) => ({
+        ...existing,
+        metadata: applyRecordPatch(existing.metadata, patch),
+        updatedAt,
+      }));
+      if (!updated) {
+        reject("Workspace not found");
+        return;
+      }
+      this.emit({
+        type: "workspace.metadata.update.response",
+        payload: {
+          requestId,
+          workspaceId,
+          accepted: true,
+          metadata: updated.metadata,
+          error: null,
+        },
+      });
+      await this.emitWorkspaceUpdatesForWorkspaceIds([workspaceId]);
+    } catch (error) {
+      this.sessionLogger.error(
+        { err: error, workspaceId, requestId },
+        "session: workspace.metadata.update.request error",
+      );
+      reject(getErrorMessageOr(error, "Failed to update workspace metadata"));
+    }
+  }
+
   private async handleWorkspacePinSetRequest(
     workspaceId: string,
     pinned: boolean,
@@ -4510,6 +4588,7 @@ export class Session {
           images,
           attachments,
           labels: resolvedIntent.intent.labels,
+          metadata: msg.metadata,
           env,
           provisionalTitle,
           firstAgentContext,
@@ -5710,6 +5789,7 @@ export class Session {
       title: workspace.title,
       pinnedAt: workspace.pinnedAt,
       ...(workspace.labels && workspace.labels.length > 0 ? { labels: workspace.labels } : {}),
+      metadata: workspace.metadata,
       background: workspace.background,
       archivingAt: null,
       status: "done",
@@ -5808,6 +5888,7 @@ export class Session {
       ...(result.workspace.labels && result.workspace.labels.length > 0
         ? { labels: result.workspace.labels }
         : {}),
+      metadata: result.workspace.metadata,
       archivingAt: null,
       status: "done",
       statusEnteredAt: result.workspace.createdAt,
@@ -6870,6 +6951,7 @@ export class Session {
       {
         expectsInitialAgent: Boolean(request.firstAgentContext),
         workspaceId,
+        metadata: request.metadata,
         background: request.background,
         callerWorkspaceId: this.getCallerWorkspaceId(request.callerAgentId),
       },
@@ -6934,6 +7016,7 @@ export class Session {
         githubPrNumber: source.githubPrNumber,
         firstAgentContext: request.firstAgentContext,
         title: request.title,
+        metadata: request.metadata,
         background: request.background,
         callerWorkspaceId: this.getCallerWorkspaceId(request.callerAgentId),
       },
diff --git a/packages/server/src/server/session/workspace-provisioning/workspace-provisioning-service.ts b/packages/server/src/server/session/workspace-provisioning/workspace-provisioning-service.ts
index 08d7b93bf4..a22b650bf5 100644
--- a/packages/server/src/server/session/workspace-provisioning/workspace-provisioning-service.ts
+++ b/packages/server/src/server/session/workspace-provisioning/workspace-provisioning-service.ts
@@ -1,3 +1,4 @@
+import type { JsonValue } from "@getpaseo/protocol/agent-types";
 import type { PluginLifecycle } from "../../plugins/lifecycle/index.js";
 import { describeHookWorkspace } from "../../plugins/lifecycle/index.js";
 import { basename, resolve } from "node:path";
@@ -50,6 +51,7 @@ export interface CreateWorktreeWorkspaceInput {
   branch: string | null;
   baseBranch: string | null;
   title: string | null;
+  metadata?: Record<string, JsonValue>;
   expectsInitialAgent?: boolean;
   untrustedSource?: UntrustedWorkspaceSource;
   background?: boolean;
@@ -70,6 +72,7 @@ export interface WorkspaceProvisioningService {
     context?: {
       expectsInitialAgent?: boolean;
       workspaceId?: string;
+      metadata?: Record<string, JsonValue>;
       background?: boolean;
       callerWorkspaceId?: string;
     },
@@ -242,6 +245,7 @@ export function createWorkspaceProvisioningService(deps: {
     context?: {
       expectsInitialAgent?: boolean;
       workspaceId?: string;
+      metadata?: Record<string, JsonValue>;
       background?: boolean;
       callerWorkspaceId?: string;
     },
@@ -258,6 +262,7 @@ export function createWorkspaceProvisioningService(deps: {
       projectId: project.projectId,
       ...initialWorkspacePlacement({ source: "checkout", cwd: normalizedCwd, checkout }),
       title: title?.trim() || null,
+      metadata: context?.metadata,
       createdAt: timestamp,
       updatedAt: timestamp,
       background: await resolveBackground(context),
@@ -294,6 +299,7 @@ export function createWorkspaceProvisioningService(deps: {
         mainRepoRoot: repoRoot,
       }),
       title: input.title,
+      metadata: input.metadata,
       createdAt: timestamp,
       updatedAt: timestamp,
       ...(input.untrustedSource ? { untrustedSource: input.untrustedSource } : {}),
diff --git a/packages/server/src/server/websocket-server.ts b/packages/server/src/server/websocket-server.ts
index 2c3828353e..3c4da5f69b 100644
--- a/packages/server/src/server/websocket-server.ts
+++ b/packages/server/src/server/websocket-server.ts
@@ -2012,6 +2012,7 @@ export class VoiceAssistantWebSocketServer {
         usageSources: true,
         ownedSubscriptions: true,
         providerOptionControls: true,
+        entityMetadata: true,
         binaryChunkingV1: true,
         agentRequestReceipts: true,
         workspaceRequestReceipts: true,
diff --git a/packages/server/src/server/workspace-registry.ts b/packages/server/src/server/workspace-registry.ts
index 61fcb4f720..d49be7d001 100644
--- a/packages/server/src/server/workspace-registry.ts
+++ b/packages/server/src/server/workspace-registry.ts
@@ -1,3 +1,4 @@
+import type { JsonValue } from "@getpaseo/protocol/agent-types";
 import { promises as fs } from "node:fs";
 
 import type { Logger } from "pino";
@@ -101,6 +102,8 @@ const PersistedWorkspaceRecordSchema = z.object({
     .optional()
     .transform((value) => value ?? null),
   labels: z.array(z.string()).optional(),
+  // Plugin-owned data. Paseo stores it and never reads a key.
+  metadata: z.record(z.string(), z.custom<JsonValue>()).default({}),
   untrustedSource: UntrustedWorkspaceSourceSchema.optional(),
   // Public discovery visibility. Contents retain their ordinary lifecycle.
   background: z.boolean().optional().default(false),
@@ -678,6 +681,7 @@ export function createPersistedWorkspaceRecord(input: {
   autoArchivedChangeRequestUrl?: string | null;
   pinnedAt?: string | null;
   labels?: string[];
+  metadata?: Record<string, JsonValue>;
   untrustedSource?: UntrustedWorkspaceSource;
   background?: boolean;
 }): PersistedWorkspaceRecord {
diff --git a/public-docs/plugins/hooks.md b/public-docs/plugins/hooks.md
index 788a3df112..19fff88f68 100644
--- a/public-docs/plugins/hooks.md
+++ b/public-docs/plugins/hooks.md
@@ -49,22 +49,22 @@ Paseo only sees the returned promise, so detached work gets no error reporting a
 
 ## Hooks
 
-| Hook                      | Waits | Payload                                | Handler may change                             |
-| ------------------------- | ----- | -------------------------------------- | ---------------------------------------------- |
-| `workspace.create.before` | yes   | `{ request }`                          | Entire create request                          |
-| `workspace.create.after`  | no    | `{ workspace }`                        |                                                |
-| `workspace.archive.after` | no    | `{ workspace }`                        |                                                |
-| `worktree.create.before`  | yes   | `{ request }`                          | Creation options and destination               |
-| `worktree.create.after`   | yes   | `{ worktree }`                         | Files in the worktree; throw to abort creation |
-| `agent.create.before`     | yes   | `{ request: { config, env? } }`        | Saved config except `cwd`; `env`               |
-| `agent.create.after`      | no    | `{ agent }`                            |                                                |
-| `agent.open.before`       | yes   | `{ request }`                          | Launch-only `env`, `tools`, `mcpServers`       |
-| `agent.close.after`       | no    | `{ agent }`                            |                                                |
-| `agent.archive.after`     | no    | `{ agent, archivedAt }`                |                                                |
-| `agent.turn.before`       | no    | `{ agent, turnId }`                    |                                                |
-| `agent.turn.after`        | no    | `{ agent, turnId, outcome, timeline }` |                                                |
-| `agent.permission.before` | no    | `{ agent, request }`                   |                                                |
-| `agent.permission.after`  | no    | `{ agent, requestId, resolution }`     |                                                |
+| Hook                      | Waits | Payload                                   | Handler may change                             |
+| ------------------------- | ----- | ----------------------------------------- | ---------------------------------------------- |
+| `workspace.create.before` | yes   | `{ request }`                             | Entire create request                          |
+| `workspace.create.after`  | no    | `{ workspace }`                           |                                                |
+| `workspace.archive.after` | no    | `{ workspace }`                           |                                                |
+| `worktree.create.before`  | yes   | `{ request }`                             | Creation options and destination               |
+| `worktree.create.after`   | yes   | `{ worktree }`                            | Files in the worktree; throw to abort creation |
+| `agent.create.before`     | yes   | `{ request: { config, env?, metadata } }` | Saved config except `cwd`; `env`; `metadata`   |
+| `agent.create.after`      | no    | `{ agent }`                               |                                                |
+| `agent.open.before`       | yes   | `{ request }`                             | Launch-only `env`, `tools`, `mcpServers`       |
+| `agent.close.after`       | no    | `{ agent }`                               |                                                |
+| `agent.archive.after`     | no    | `{ agent, archivedAt }`                   |                                                |
+| `agent.turn.before`       | no    | `{ agent, turnId }`                       |                                                |
+| `agent.turn.after`        | no    | `{ agent, turnId, outcome, timeline }`    |                                                |
+| `agent.permission.before` | no    | `{ agent, request }`                      |                                                |
+| `agent.permission.after`  | no    | `{ agent, requestId, resolution }`        |                                                |
 
 ## Shared payloads
 
@@ -76,6 +76,7 @@ interface PluginHookAgent {
   provider: string;
   cwd: string;
   title: string | null;
+  metadata: Record<string, JsonValue>;
 }
 
 interface PluginHookWorkspace {
@@ -84,6 +85,7 @@ interface PluginHookWorkspace {
   cwd: string;
   name: string | null;
   archivedAt: string | null;
+  metadata: Record<string, JsonValue>;
 }
 
 type PluginTurnOutcome =
@@ -100,9 +102,29 @@ type PluginTurnOutcome =
 | `resolution` | SDK `AgentPermissionResponse`                                                          |
 | `archivedAt` | Timestamp string                                                                       |
 
+## Metadata
+
+Agents and workspaces carry a `metadata` record for plugin data. Keys are strings, values are any JSON value, and Paseo stores the record without reading a key. Prefix keys with your plugin id so plugins do not collide. Labels stay strings for filtering and tagging; use metadata for structured data.
+
+Set metadata when you create the agent or workspace, or change it later. `null` removes a key, and any other value replaces the key's whole value:
+
+```ts
+const agent = await paseo.agents.create({
+  config: { provider: "codex/gpt-5.5" },
+  cwd: "/projects/shop",
+  metadata: { "linear.issue": { id: "ENG-123" } },
+});
+
+agent.metadata; // { "linear.issue": { id: "ENG-123" } }
+await agent.setMetadata({ "linear.issue": null });
+await paseo.workspaces.ref(workspaceId).setMetadata({ "linear.issue": { id: "ENG-123" } });
+```
+
+Metadata survives a daemon restart. Every hook payload carries it: `workspace.create.before` and `agent.create.before` receive the metadata the caller sent, and the `after` hooks and `agent.open.before` receive what is stored. Against a host that predates metadata, these calls throw "Update the host to use metadata."
+
 ## workspace.create.before
 
-Receives `{ request }` with `source`, optional `title`, and `firstAgentContext`. You may replace the entire explicit create request; a throw, invalid result, or timeout fails creation. Existing workspaces and directory lookup/import are unaffected.
+Receives `{ request }` with `source`, optional `title`, optional `metadata`, and `firstAgentContext`. You may replace the entire explicit create request; a throw, invalid result, or timeout fails creation. Existing workspaces and directory lookup/import are unaffected.
 
 ### Choose workspace isolation
 
@@ -202,7 +224,7 @@ server.addHook("worktree.create.after", async ({ worktree }) => {
 
 ## agent.create.before
 
-Receives `{ request: { config, env? } }`. Config changes are saved and remain after the plugin is disabled or removed; `env` applies to the initial launch and is not saved. You cannot change `config.cwd`. A throw, invalid result, or timeout fails creation.
+Receives `{ request: { config, env?, metadata } }`. Config and `metadata` changes are saved and remain after the plugin is disabled or removed; `env` applies to the initial launch and is not saved. You cannot change `config.cwd`. A throw, invalid result, or timeout fails creation.
 
 **`agent.create.before.config`** uses `AgentSessionConfig`:
 
@@ -271,6 +293,7 @@ Receives `{ request }`; only `env`, `tools`, and `mcpServers` may change, for th
   "cwd": "/projects/shop",
   "title": "Workspace notes",
   "labels": { "notes/enabled": "true" },
+  "metadata": { "linear.issue": { "id": "ENG-123" } },
   "tools": [],
   "mcpServers": {},
   "reason": "resume",
@@ -284,6 +307,7 @@ Receives `{ request }`; only `env`, `tools`, and `mcpServers` may change, for th
 | `workspaceId` | String or `null`                                                                                                        |
 | `title`       | Read-only string or `null`; creation title on create, stored title on resume.                                           |
 | `labels`      | Read-only string map; creation labels on create, stored labels on resume.                                               |
+| `metadata`    | Read-only JSON map; the [metadata](#metadata) stored on the agent.                                                      |
 | `tools`       | Editable `AgentToolDefinition[]`, local to this plugin. See [Attach tools to agents](#attach-tools-to-agents).          |
 | `mcpServers`  | Editable launch-only server map, local to this plugin. See [Inject MCP servers](#inject-mcp-servers).                   |
 | `reason`      | `create`, `resume`, `refresh`, `import`                                                                                 |
diff --git a/public-docs/plugins/hooks.zh-CN.md b/public-docs/plugins/hooks.zh-CN.md
index b971b5df76..cd5daf2f50 100644
--- a/public-docs/plugins/hooks.zh-CN.md
+++ b/public-docs/plugins/hooks.zh-CN.md
@@ -47,22 +47,22 @@ Paseo 只观察返回的 Promise，因此独立任务没有错误报告，也没
 
 ## 钩子一览 {#hooks}
 
-| 钩子                      | 等待 | 载荷                                   | 可修改                                    |
-| ------------------------- | ---- | -------------------------------------- | ----------------------------------------- |
-| `workspace.create.before` | 是   | `{ request }`                          | 整个创建请求                              |
-| `workspace.create.after`  | 否   | `{ workspace }`                        |                                           |
-| `workspace.archive.after` | 否   | `{ workspace }`                        |                                           |
-| `worktree.create.before`  | 是   | `{ request }`                          | 创建选项和目标路径                        |
-| `worktree.create.after`   | 是   | `{ worktree }`                         | worktree 中的文件；抛出错误中止创建       |
-| `agent.create.before`     | 是   | `{ request: { config, env? } }`        | 除 `cwd` 外的已保存配置；`env`            |
-| `agent.create.after`      | 否   | `{ agent }`                            |                                           |
-| `agent.open.before`       | 是   | `{ request }`                          | 仅用于启动的 `env`、`tools`、`mcpServers` |
-| `agent.close.after`       | 否   | `{ agent }`                            |                                           |
-| `agent.archive.after`     | 否   | `{ agent, archivedAt }`                |                                           |
-| `agent.turn.before`       | 否   | `{ agent, turnId }`                    |                                           |
-| `agent.turn.after`        | 否   | `{ agent, turnId, outcome, timeline }` |                                           |
-| `agent.permission.before` | 否   | `{ agent, request }`                   |                                           |
-| `agent.permission.after`  | 否   | `{ agent, requestId, resolution }`     |                                           |
+| 钩子                      | 等待 | 载荷                                      | 可修改                                     |
+| ------------------------- | ---- | ----------------------------------------- | ------------------------------------------ |
+| `workspace.create.before` | 是   | `{ request }`                             | 整个创建请求                               |
+| `workspace.create.after`  | 否   | `{ workspace }`                           |                                            |
+| `workspace.archive.after` | 否   | `{ workspace }`                           |                                            |
+| `worktree.create.before`  | 是   | `{ request }`                             | 创建选项和目标路径                         |
+| `worktree.create.after`   | 是   | `{ worktree }`                            | worktree 中的文件；抛出错误中止创建        |
+| `agent.create.before`     | 是   | `{ request: { config, env?, metadata } }` | 除 `cwd` 外的已保存配置；`env`；`metadata` |
+| `agent.create.after`      | 否   | `{ agent }`                               |                                            |
+| `agent.open.before`       | 是   | `{ request }`                             | 仅用于启动的 `env`、`tools`、`mcpServers`  |
+| `agent.close.after`       | 否   | `{ agent }`                               |                                            |
+| `agent.archive.after`     | 否   | `{ agent, archivedAt }`                   |                                            |
+| `agent.turn.before`       | 否   | `{ agent, turnId }`                       |                                            |
+| `agent.turn.after`        | 否   | `{ agent, turnId, outcome, timeline }`    |                                            |
+| `agent.permission.before` | 否   | `{ agent, request }`                      |                                            |
+| `agent.permission.after`  | 否   | `{ agent, requestId, resolution }`        |                                            |
 
 ## 共享载荷 {#shared-payloads}
 
@@ -74,6 +74,7 @@ interface PluginHookAgent {
   provider: string;
   cwd: string;
   title: string | null;
+  metadata: Record<string, JsonValue>;
 }
 
 interface PluginHookWorkspace {
@@ -82,6 +83,7 @@ interface PluginHookWorkspace {
   cwd: string;
   name: string | null;
   archivedAt: string | null;
+  metadata: Record<string, JsonValue>;
 }
 
 type PluginTurnOutcome =
@@ -98,9 +100,29 @@ type PluginTurnOutcome =
 | `resolution` | SDK 的 `AgentPermissionResponse`                                                         |
 | `archivedAt` | 时间戳字符串                                                                             |
 
+## 元数据 {#metadata}
+
+Agent 和工作区带有 `metadata` 记录，用于保存插件数据。键是字符串，值可以是任意 JSON 值，Paseo 只保存、不读取任何键。给键加上插件 ID 前缀，避免不同插件冲突。标签仍是用于筛选和标记的字符串；结构化数据请用元数据。
+
+可以在创建 Agent 或工作区时设置元数据，也可以之后修改。`null` 删除该键，其他值会替换该键的整个值：
+
+```ts
+const agent = await paseo.agents.create({
+  config: { provider: "codex/gpt-5.5" },
+  cwd: "/projects/shop",
+  metadata: { "linear.issue": { id: "ENG-123" } },
+});
+
+agent.metadata; // { "linear.issue": { id: "ENG-123" } }
+await agent.setMetadata({ "linear.issue": null });
+await paseo.workspaces.ref(workspaceId).setMetadata({ "linear.issue": { id: "ENG-123" } });
+```
+
+元数据在 daemon 重启后仍然保留。所有钩子载荷都带有元数据：`workspace.create.before` 和 `agent.create.before` 收到调用方发送的元数据，`after` 钩子和 `agent.open.before` 收到已保存的元数据。主机版本过旧时，这些调用会抛出 “Update the host to use metadata.”。
+
 ## workspace.create.before {#workspacecreatebefore}
 
-收到 `{ request }`，其中包含 `source`、可选的 `title` 和 `firstAgentContext`。可替换整个显式创建请求；抛出错误、无效返回或超时会让创建失败。已有工作区和目录查找、导入不受影响。
+收到 `{ request }`，其中包含 `source`、可选的 `title`、可选的 `metadata` 和 `firstAgentContext`。可替换整个显式创建请求；抛出错误、无效返回或超时会让创建失败。已有工作区和目录查找、导入不受影响。
 
 ### 选择工作区隔离方式 {#choose-workspace-isolation}
 
@@ -199,7 +221,7 @@ server.addHook("worktree.create.after", async ({ worktree }) => {
 
 ## agent.create.before {#agentcreatebefore}
 
-收到 `{ request: { config, env? } }`。配置修改会保存，即使插件以后被停用或移除；`env` 只用于首次启动，不会保存。不能修改 `config.cwd`。抛出错误、无效返回或超时会让创建失败。
+收到 `{ request: { config, env?, metadata } }`。配置和 `metadata` 的修改会保存，即使插件以后被停用或移除；`env` 只用于首次启动，不会保存。不能修改 `config.cwd`。抛出错误、无效返回或超时会让创建失败。
 
 **`agent.create.before.config`** 使用 `AgentSessionConfig`：
 
@@ -267,6 +289,7 @@ server.addHook("agent.create.after", async ({ agent }) => {
   "cwd": "/projects/shop",
   "title": "Workspace notes",
   "labels": { "notes/enabled": "true" },
+  "metadata": { "linear.issue": { "id": "ENG-123" } },
   "tools": [],
   "mcpServers": {},
   "reason": "resume",
@@ -280,6 +303,7 @@ server.addHook("agent.create.after", async ({ agent }) => {
 | `workspaceId` | 字符串或 `null`                                                                                          |
 | `title`       | 只读字符串或 `null`；创建时使用创建请求的标题，恢复时使用已保存的标题。                                  |
 | `labels`      | 只读的字符串映射；创建时使用创建请求的标签，恢复时使用已保存的标签。                                     |
+| `metadata`    | 只读的 JSON 映射；Agent 上已保存的[元数据](#metadata)。                                                  |
 | `tools`       | 可编辑的 `AgentToolDefinition[]`，仅包含此插件的工具。参阅[为 Agent 附加工具](#attach-tools-to-agents)。 |
 | `mcpServers`  | 可编辑的服务器映射，仅用于启动且仅包含本插件的条目。参阅[注入 MCP 服务器](#inject-mcp-servers)。         |
 | `reason`      | `create`、`resume`、`refresh`、`import`                                                                  |