diff --git a/packages/server/src/server/agent/agent-sdk-types.ts b/packages/server/src/server/agent/agent-sdk-types.ts
index 64e5b11eca..d42d98aaf7 100644
--- a/packages/server/src/server/agent/agent-sdk-types.ts
+++ b/packages/server/src/server/agent/agent-sdk-types.ts
@@ -660,6 +660,11 @@ export interface AgentPermissionResult {
   followUpPrompt?: AgentPromptInput;
 }
 
+export interface UsageReference {
+  source: string;
+  input: JsonValue;
+}
+
 export interface AgentSession {
   readonly provider: AgentProvider;
   readonly id: string | null;
@@ -669,7 +674,7 @@ export interface AgentSession {
    * replay them at their original timestamps; restored sessions omit old rows. */
   readonly initialTimeline?: ImportedTimelineEntry[];
   /** Resolved at fetch time because model and credentials may change during a session. */
-  getUsageReference?(): Promise<{ source: string; input: JsonValue } | null>;
+  getUsageReference?(): Promise<UsageReference | null>;
   run(prompt: AgentPromptInput, options?: AgentRunOptions): Promise<AgentRunResult>;
   startTurn(prompt: AgentPromptInput, options?: AgentRunOptions): Promise<{ turnId: string }>;
   steerActiveTurn?(prompt: AgentPromptInput, options: SteerActiveTurnOptions): Promise<SteerResult>;
diff --git a/packages/server/src/server/agent/plugin-provider.ts b/packages/server/src/server/agent/plugin-provider.ts
index bd5a7d9986..2ebeb3c797 100644
--- a/packages/server/src/server/agent/plugin-provider.ts
+++ b/packages/server/src/server/agent/plugin-provider.ts
@@ -51,6 +51,7 @@ import type {
   ProviderRefreshContext,
   SteerActiveTurnOptions,
   SteerResult,
+  UsageReference,
 } from "./agent-sdk-types.js";
 import {
   isDefaultAgentCreateConfigUnattended,
@@ -567,7 +568,7 @@ class ProviderRuntimeSession {
     return this.capabilities;
   }
 
-  async getUsageReference(): Promise<{ source: string; input: JsonValue } | null> {
+  async getUsageReference(): Promise<UsageReference | null> {
     if (!this.capabilities.includes("session.usage_reference")) return null;
     const event = await this.runtime.complete({
       type: "session.usage_reference",
@@ -1087,7 +1088,7 @@ class PluginAgentSession implements AgentSession {
     return agentCapabilities(this.bridge.negotiatedCapabilities);
   }
 
-  getUsageReference(): Promise<{ source: string; input: JsonValue } | null> {
+  getUsageReference(): Promise<UsageReference | null> {
     return this.bridge.getUsageReference();
   }
 
diff --git a/packages/server/src/server/agent/providers/opencode-agent.ts b/packages/server/src/server/agent/providers/opencode-agent.ts
index 0de0d4cd33..e3100025a5 100644
--- a/packages/server/src/server/agent/providers/opencode-agent.ts
+++ b/packages/server/src/server/agent/providers/opencode-agent.ts
@@ -58,6 +58,7 @@ import {
   type SteerResult,
   type ToolCallDetail,
   type ToolCallTimelineItem,
+  type UsageReference,
 } from "../agent-sdk-types.js";
 import { importSessionFromPersistence } from "../provider-session-import.js";
 import {
@@ -3390,7 +3391,7 @@ async function readOpenCodeUsageAuth(
 function resolveOpenCodeUsageReference(
   model: string,
   auth: Record<string, unknown> | null,
-): { source: string; input: import("@getpaseo/protocol/agent-types").JsonValue } | null {
+): UsageReference | null {
   if (!auth) return null;
   if (model.startsWith("openai/")) {
     const entry = auth.openai;
@@ -3607,10 +3608,7 @@ class OpenCodeAgentSession implements AgentSession {
     };
   }
 
-  async getUsageReference(): Promise<{
-    source: string;
-    input: import("@getpaseo/protocol/agent-types").JsonValue;
-  } | null> {
+  async getUsageReference(): Promise<UsageReference | null> {
     const model = this.config.model;
     if (!model?.startsWith("openai/") && !model?.startsWith("opencode-go/")) return null;
     const auth = await readOpenCodeUsageAuth(this.usageEnv);
diff --git a/packages/server/src/server/plugins/index.ts b/packages/server/src/server/plugins/index.ts
index f49bd95e48..2b0c943cf5 100644
--- a/packages/server/src/server/plugins/index.ts
+++ b/packages/server/src/server/plugins/index.ts
@@ -28,6 +28,7 @@ import type { PluginProviderMetadata } from "./plugin-process-protocol.js";
 import { readPluginProviderIcon } from "./provider-icon.js";
 import { UsageSourceRegistry } from "./usage-sources/index.js";
 import type { PluginUsageSourceMetadata } from "./plugin-process-protocol.js";
+import type { UsageReference } from "../agent/agent-sdk-types.js";
 
 const BUILTIN_PROVIDER_ID_SET: ReadonlySet<string> = new Set(BUILTIN_PROVIDER_IDS);
 
@@ -142,17 +143,11 @@ export class PluginService {
     return [...this.providers.values()].sort((left, right) => left.id.localeCompare(right.id));
   }
 
-  listUsageReports(options?: {
-    forceRefresh?: boolean;
-    references?: Array<{ source: string; input: unknown }>;
-  }) {
+  listUsageReports(options?: { forceRefresh?: boolean; references?: UsageReference[] }) {
     return this.usageSources.listReports(options);
   }
 
-  fetchUsageReference(
-    reference: { source: string; input: unknown },
-    options?: { forceRefresh?: boolean },
-  ) {
+  fetchUsageReference(reference: UsageReference, options?: { forceRefresh?: boolean }) {
     return this.usageSources.fetchReference(reference, options);
   }
 
diff --git a/packages/server/src/server/plugins/session-usage-reference.e2e.test.ts b/packages/server/src/server/plugins/session-usage-reference.e2e.test.ts
index 1c8512f805..f35cc1e021 100644
--- a/packages/server/src/server/plugins/session-usage-reference.e2e.test.ts
+++ b/packages/server/src/server/plugins/session-usage-reference.e2e.test.ts
@@ -1,6 +1,7 @@
 import { fileURLToPath } from "node:url";
 import { expect, test } from "vitest";
 import { ACPAgentSession } from "../agent/providers/acp-agent.js";
+import type { UsageReference } from "../agent/agent-sdk-types.js";
 import { ClaudeAgentClient } from "../agent/providers/claude/agent.js";
 import { CodexAppServerAgentSession } from "../agent/providers/codex-app-server-agent.js";
 import { createTestLogger } from "../../test-utils/test-logger.js";
@@ -49,7 +50,7 @@ test("agent.get_usage_report resolves source IDs from default built-in and ACP s
   );
   const providers = ["claude", "codex", "copilot", "cursor", "kimi", "generic-acp"] as const;
   const logger = createTestLogger();
-  const references = new Map<string, { source: string; input: Record<string, string> } | null>();
+  const references = new Map<string, UsageReference | null>();
   const claude = await new ClaudeAgentClient({
     logger,
     resolveBinary: async () => "/test/claude/bin",
diff --git a/packages/server/src/server/plugins/usage-sources/index.ts b/packages/server/src/server/plugins/usage-sources/index.ts
index cb52f98328..686a3e509a 100644
--- a/packages/server/src/server/plugins/usage-sources/index.ts
+++ b/packages/server/src/server/plugins/usage-sources/index.ts
@@ -4,6 +4,7 @@ import {
   type UsageReportEntry,
   type ProviderUsage,
 } from "@getpaseo/protocol/messages";
+import type { UsageReference } from "../../agent/agent-sdk-types.js";
 
 export interface UsageSource {
   id: string;
@@ -37,7 +38,7 @@ export class UsageSourceRegistry {
   async listReports(
     options: {
       forceRefresh?: boolean;
-      references?: Array<{ source: string; input: unknown }>;
+      references?: UsageReference[];
     } = {},
   ): Promise<UsageReportEntry[]> {
     const discovered = await Promise.all(
@@ -67,7 +68,7 @@ export class UsageSourceRegistry {
   }
 
   fetchReference(
-    reference: { source: string; input: unknown },
+    reference: UsageReference,
     options: { forceRefresh?: boolean } = {},
   ): Promise<UsageReportEntry | null> {
     return this.sources.has(reference.source)
diff --git a/packages/server/src/server/session.ts b/packages/server/src/server/session.ts
index 9d6c1d79cf..893021ec67 100644
--- a/packages/server/src/server/session.ts
+++ b/packages/server/src/server/session.ts
@@ -134,6 +134,7 @@ import {
   type AgentPermissionResponse,
   type AgentRunOptions,
   type AgentSessionConfig,
+  type UsageReference,
 } from "./agent/agent-sdk-types.js";
 import type { StoredAgentRecord } from "./agent/agent-storage.js";
 import type { AgentStorage } from "./agent/agent-storage.js";
@@ -511,10 +512,10 @@ export interface SessionOptions {
     invokePluginRpc(pluginId: string, method: string, input: unknown): Promise<unknown>;
     listUsageReports(options?: {
       forceRefresh?: boolean;
-      references?: Array<{ source: string; input: unknown }>;
+      references?: UsageReference[];
     }): Promise<UsageReportEntry[]>;
     fetchUsageReference(
-      reference: { source: string; input: unknown },
+      reference: UsageReference,
       options?: { forceRefresh?: boolean },
     ): Promise<UsageReportEntry | null>;
     listLegacyUsage(): Promise<{ fetchedAt: string; providers: ProviderUsage[] }>;